├── .gitignore ├── Chapter01 ├── .gitignore └── helloworld.c ├── Chapter02 ├── add_custom_code.patch ├── module │ ├── Makefile │ └── dummy-code.c └── module_par │ ├── Makefile │ └── module_par.c ├── Chapter03 ├── .gitignore ├── chrdev_legacy │ ├── Makefile │ ├── chrdev_legacy.c │ └── modify_read_write_to_chrdev_legacy.patch ├── chrdev_test.c └── modify_close_open_to_chrdev_test.patch ├── Chapter04 ├── chrdev │ ├── Makefile │ ├── add_chrdev_devices.dts.patch │ ├── add_fixed_chrdev_devices.patch │ ├── add_sysfs_attrs_chrdev.patch │ ├── chrdev-fw.c │ ├── chrdev-req.c │ ├── chrdev.c │ └── chrdev.h ├── get_dt_data │ ├── Makefile │ └── get_dt_data.c └── simple_platform │ ├── .gitignore │ └── simple_platform.dts ├── Chapter05 ├── add_irqtest_module.patch ├── add_tasklet_2_to_irqtest_module.patch ├── add_tasklet_to_irqtest_module.patch ├── add_workqueue_2_to_irqtest_module.patch ├── add_workqueue_to_irqtest_module.patch ├── atomic │ ├── Makefile │ ├── atomic.c │ ├── mutex.c │ └── spinlock.c ├── notifier │ ├── Makefile │ ├── hires_timer.c │ └── notifier.c ├── timer │ ├── Makefile │ ├── hires_timer.c │ └── ktimer.c └── wait_event │ ├── Makefile │ ├── completion.c │ └── waitqueue.c ├── Chapter06 ├── data_types │ ├── Makefile │ └── data_types.c ├── hashtable │ ├── Makefile │ └── hashtable.c ├── helper_funcs │ ├── Makefile │ └── helper_funcs.c ├── list │ ├── Makefile │ └── list.c ├── mem_alloc │ ├── Makefile │ └── mem_alloc.c └── time │ ├── Makefile │ └── time.c ├── Chapter07 ├── .gitignore ├── chrdev │ ├── Makefile │ ├── add_mutex_to_chrdev.patch │ ├── chrdev-req.c │ ├── chrdev.c │ ├── chrdev.h │ ├── chrdev_ioctl.h │ ├── chrdev_irq.c │ ├── chrdev_irq.h │ └── modify_lseek_to_chrdev_test.patch ├── chrdev_fasync.c ├── chrdev_ioctl.c ├── chrdev_mmap.c └── chrdev_select.c ├── LICENSE └── README.md /.gitignore: -------------------------------------------------------------------------------- 1 | .tmp_versions/ 2 | *.o 3 | *.ko 4 | *.mod.c 5 | *.o.cmd 6 | *.ko.cmd 7 | Module.symvers 8 | modules.order 9 | -------------------------------------------------------------------------------- /Chapter01/.gitignore: -------------------------------------------------------------------------------- 1 | hardcopy.0 2 | helloworld 3 | helloworld.x86_64 4 | -------------------------------------------------------------------------------- /Chapter01/helloworld.c: -------------------------------------------------------------------------------- 1 | #include 2 | 3 | int main(int argc, char *argv[]) 4 | { 5 | printf("Hello World!\n"); 6 | 7 | return 0; 8 | } 9 | -------------------------------------------------------------------------------- /Chapter02/add_custom_code.patch: -------------------------------------------------------------------------------- 1 | diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig 2 | index 3726eacdf65d..64aa35c08eee 100644 3 | --- a/drivers/misc/Kconfig 4 | +++ b/drivers/misc/Kconfig 5 | @@ -527,4 +527,10 @@ source "drivers/misc/echo/Kconfig" 6 | source "drivers/misc/cxl/Kconfig" 7 | source "drivers/misc/ocxl/Kconfig" 8 | source "drivers/misc/cardreader/Kconfig" 9 | + 10 | +config DUMMY_CODE 11 | + tristate "Dummy code" 12 | + default n 13 | + ---help--- 14 | + This module is just for demonstration purposes. 15 | endmenu 16 | diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile 17 | index af22bbc3d00c..47ee613df600 100644 18 | --- a/drivers/misc/Makefile 19 | +++ b/drivers/misc/Makefile 20 | @@ -58,3 +58,4 @@ obj-$(CONFIG_ASPEED_LPC_SNOOP) += aspeed-lpc-snoop.o 21 | obj-$(CONFIG_PCI_ENDPOINT_TEST) += pci_endpoint_test.o 22 | obj-$(CONFIG_OCXL) += ocxl/ 23 | obj-$(CONFIG_MISC_RTSX) += cardreader/ 24 | +obj-$(CONFIG_DUMMY_CODE) += dummy-code.o 25 | diff --git a/drivers/misc/dummy-code.c b/drivers/misc/dummy-code.c 26 | new file mode 100644 27 | index 000000000000..c1bbbdfed873 28 | --- /dev/null 29 | +++ b/drivers/misc/dummy-code.c 30 | @@ -0,0 +1,23 @@ 31 | +/* 32 | + * Dummy code 33 | + */ 34 | + 35 | +#include 36 | + 37 | +static int __init dummy_code_init(void) 38 | +{ 39 | + printk(KERN_INFO "dummy-code loaded\n"); 40 | + return 0; 41 | +} 42 | + 43 | +static void __exit dummy_code_exit(void) 44 | +{ 45 | + printk(KERN_INFO "dummy-code unloaded\n"); 46 | +} 47 | + 48 | +module_init(dummy_code_init); 49 | +module_exit(dummy_code_exit); 50 | + 51 | +MODULE_LICENSE("GPL"); 52 | +MODULE_AUTHOR("Rodolfo Giometti"); 53 | +MODULE_DESCRIPTION("Dummy code"); 54 | -------------------------------------------------------------------------------- /Chapter02/module/Makefile: -------------------------------------------------------------------------------- 1 | ifndef KERNEL_DIR 2 | $(error KERNEL_DIR must be set in the command line) 3 | endif 4 | PWD := $(shell pwd) 5 | ARCH ?= arm64 6 | CROSS_COMPILE ?= aarch64-linux-gnu- 7 | 8 | # This specifies the kernel module to be compiled 9 | obj-m += dummy-code.o 10 | 11 | # The default action 12 | all: modules 13 | 14 | # The main tasks 15 | modules clean: 16 | make -C $(KERNEL_DIR) \ 17 | ARCH=$(ARCH) \ 18 | CROSS_COMPILE=$(CROSS_COMPILE) \ 19 | SUBDIRS=$(PWD) $@ 20 | -------------------------------------------------------------------------------- /Chapter02/module/dummy-code.c: -------------------------------------------------------------------------------- 1 | /* 2 | * Dummy code 3 | */ 4 | 5 | #define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__ 6 | #include 7 | 8 | static int __init dummy_code_init(void) 9 | { 10 | pr_info("dummy-code loaded\n"); 11 | return 0; 12 | } 13 | 14 | static void __exit dummy_code_exit(void) 15 | { 16 | pr_info("dummy-code unloaded\n"); 17 | } 18 | 19 | module_init(dummy_code_init); 20 | module_exit(dummy_code_exit); 21 | 22 | MODULE_LICENSE("GPL"); 23 | MODULE_AUTHOR("Rodolfo Giometti"); 24 | MODULE_DESCRIPTION("Dummy code"); 25 | -------------------------------------------------------------------------------- /Chapter02/module_par/Makefile: -------------------------------------------------------------------------------- 1 | ifndef KERNEL_DIR 2 | $(error KERNEL_DIR must be set in the command line) 3 | endif 4 | PWD := $(shell pwd) 5 | ARCH ?= arm64 6 | CROSS_COMPILE ?= aarch64-linux-gnu- 7 | 8 | # This specifies the kernel module to be compiled 9 | obj-m += module_par.o 10 | 11 | # The default action 12 | all: modules 13 | 14 | # The main tasks 15 | modules clean: 16 | make -C $(KERNEL_DIR) \ 17 | ARCH=$(ARCH) \ 18 | CROSS_COMPILE=$(CROSS_COMPILE) \ 19 | SUBDIRS=$(PWD) $@ 20 | -------------------------------------------------------------------------------- /Chapter02/module_par/module_par.c: -------------------------------------------------------------------------------- 1 | /* 2 | * Module with parameters 3 | */ 4 | 5 | #define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__ 6 | #include 7 | #include 8 | 9 | static int var = 0x3f; 10 | module_param(var, int, S_IRUSR | S_IWUSR); 11 | MODULE_PARM_DESC(var, "an integer value"); 12 | 13 | static char *str = "default string"; 14 | module_param(str, charp, S_IRUSR | S_IWUSR); 15 | MODULE_PARM_DESC(str, "a string value"); 16 | 17 | #define ARR_SIZE 8 18 | static int arr[ARR_SIZE]; 19 | static int arr_count; 20 | module_param_array(arr, int, &arr_count, S_IRUSR | S_IWUSR); 21 | MODULE_PARM_DESC(arr, "an array of " __stringify(ARR_SIZE) " values"); 22 | 23 | /* 24 | * Init & exit stuff 25 | */ 26 | 27 | static int __init module_par_init(void) 28 | { 29 | int i; 30 | 31 | pr_info("loaded\n"); 32 | pr_info("var = 0x%02x\n", var); 33 | pr_info("str = \"%s\"\n", str); 34 | pr_info("arr = "); 35 | for (i = 0; i < ARR_SIZE; i++) 36 | pr_cont("%d ", arr[i]); 37 | pr_cont("\n"); 38 | 39 | return 0; 40 | } 41 | 42 | static void __exit module_par_exit(void) 43 | { 44 | pr_info("unloaded\n"); 45 | } 46 | 47 | module_init(module_par_init); 48 | module_exit(module_par_exit); 49 | 50 | MODULE_LICENSE("GPL"); 51 | MODULE_AUTHOR("Rodolfo Giometti"); 52 | MODULE_DESCRIPTION("Module with parameters"); 53 | MODULE_VERSION("0.1"); 54 | -------------------------------------------------------------------------------- /Chapter03/.gitignore: -------------------------------------------------------------------------------- 1 | chrdev_test 2 | -------------------------------------------------------------------------------- /Chapter03/chrdev_legacy/Makefile: -------------------------------------------------------------------------------- 1 | ifndef KERNEL_DIR 2 | $(error KERNEL_DIR must be set in the command line) 3 | endif 4 | PWD := $(shell pwd) 5 | ARCH ?= arm64 6 | CROSS_COMPILE ?= aarch64-linux-gnu- 7 | 8 | obj-m = chrdev_legacy.o 9 | 10 | all: modules 11 | 12 | modules clean: 13 | make -C $(KERNEL_DIR) \ 14 | ARCH=$(ARCH) \ 15 | CROSS_COMPILE=$(CROSS_COMPILE) \ 16 | SUBDIRS=$(PWD) $@ 17 | -------------------------------------------------------------------------------- /Chapter03/chrdev_legacy/chrdev_legacy.c: -------------------------------------------------------------------------------- 1 | /* 2 | * chrdev legacy 3 | */ 4 | 5 | #define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__ 6 | #include 7 | #include 8 | #include 9 | 10 | /* Device major umber */ 11 | static int major; 12 | 13 | /* 14 | * Methods 15 | */ 16 | 17 | static ssize_t chrdev_read(struct file *filp, 18 | char __user *buf, size_t count, loff_t *ppos) 19 | { 20 | pr_info("return EOF\n"); 21 | 22 | return 0; 23 | } 24 | 25 | static ssize_t chrdev_write(struct file *filp, 26 | const char __user *buf, size_t count, loff_t *ppos) 27 | { 28 | pr_info("got %ld bytes\n", count); 29 | 30 | *ppos += count; 31 | return count; 32 | } 33 | 34 | static int chrdev_open(struct inode *inode, struct file *filp) 35 | { 36 | pr_info("chrdev opened\n"); 37 | 38 | return 0; 39 | } 40 | 41 | static int chrdev_release(struct inode *inode, struct file *filp) 42 | { 43 | pr_info("chrdev released\n"); 44 | 45 | return 0; 46 | } 47 | 48 | static struct file_operations chrdev_fops = { 49 | .owner = THIS_MODULE, 50 | .read = chrdev_read, 51 | .write = chrdev_write, 52 | .open = chrdev_open, 53 | .release = chrdev_release 54 | }; 55 | 56 | /* 57 | * Module stuff 58 | */ 59 | 60 | static int __init chrdev_init(void) 61 | { 62 | int ret; 63 | 64 | ret = register_chrdev(0, "chrdev", &chrdev_fops); 65 | if (ret < 0) { 66 | pr_err("unable to register char device! Error %d\n", ret); 67 | return ret; 68 | } 69 | major = ret; 70 | pr_info("got major %d\n", major); 71 | 72 | return 0; 73 | } 74 | 75 | static void __exit chrdev_exit(void) 76 | { 77 | unregister_chrdev(major, "chrdev"); 78 | } 79 | 80 | module_init(chrdev_init); 81 | module_exit(chrdev_exit); 82 | 83 | MODULE_LICENSE("GPL"); 84 | MODULE_AUTHOR("Rodolfo Giometti"); 85 | MODULE_DESCRIPTION("chrdev legacy"); 86 | -------------------------------------------------------------------------------- /Chapter03/chrdev_legacy/modify_read_write_to_chrdev_legacy.patch: -------------------------------------------------------------------------------- 1 | diff --git a/chapter_3/chrdev_legacy/chrdev_legacy.c b/chapter_3/chrdev_legacy/chrdev_legacy.c 2 | index 2fc25bc..401df1a 100644 3 | --- a/chapter_3/chrdev_legacy/chrdev_legacy.c 4 | +++ b/chapter_3/chrdev_legacy/chrdev_legacy.c 5 | @@ -6,10 +6,15 @@ 6 | #include 7 | #include 8 | #include 9 | +#include 10 | 11 | /* Device major umber */ 12 | static int major; 13 | 14 | +/* Device data */ 15 | +#define BUF_LEN 300 16 | +static char chrdev_buf[BUF_LEN]; 17 | + 18 | /* 19 | * Methods 20 | */ 21 | @@ -17,17 +22,44 @@ static int major; 22 | static ssize_t chrdev_read(struct file *filp, 23 | char __user *buf, size_t count, loff_t *ppos) 24 | { 25 | - pr_info("return EOF\n"); 26 | + int ret; 27 | 28 | - return 0; 29 | + pr_info("should read %ld bytes (*ppos=%lld)\n", count, *ppos); 30 | + 31 | + /* Check for end-of-buffer */ 32 | + if (*ppos + count >= BUF_LEN) 33 | + count = BUF_LEN - *ppos; 34 | + 35 | + /* Return data to the user space */ 36 | + ret = copy_to_user(buf, chrdev_buf + *ppos, count); 37 | + if (ret < 0) 38 | + return ret; 39 | + 40 | + *ppos += count; 41 | + pr_info("return %ld bytes (*ppos=%lld)\n", count, *ppos); 42 | + 43 | + return count; 44 | } 45 | 46 | static ssize_t chrdev_write(struct file *filp, 47 | const char __user *buf, size_t count, loff_t *ppos) 48 | { 49 | - pr_info("got %ld bytes\n", count); 50 | + int ret; 51 | + 52 | + pr_info("should write %ld bytes (*ppos=%lld)\n", count, *ppos); 53 | + 54 | + /* Check for end-of-buffer */ 55 | + if (*ppos + count >= BUF_LEN) 56 | + count = BUF_LEN - *ppos; 57 | + 58 | + /* Get data from the user space */ 59 | + ret = copy_from_user(chrdev_buf + *ppos, buf, count); 60 | + if (ret < 0) 61 | + return ret; 62 | + 63 | + *ppos += count; 64 | + pr_info("got %ld bytes (*ppos=%lld)\n", count, *ppos); 65 | 66 | - *ppos += count; 67 | return count; 68 | } 69 | 70 | -------------------------------------------------------------------------------- /Chapter03/chrdev_test.c: -------------------------------------------------------------------------------- 1 | /* 2 | * chrdev testing program 3 | */ 4 | 5 | #include 6 | #include 7 | #include 8 | #include 9 | #include 10 | #include 11 | #include 12 | 13 | void dump(char *str, char *buf, int size) 14 | { 15 | int i; 16 | 17 | if (size <= 0) 18 | return; 19 | 20 | printf("%s", str); 21 | for (i = 0; i < size; i++) 22 | printf("%02x ", buf[i]); 23 | printf("\n"); 24 | } 25 | 26 | int main(int argc, char *argv[]) 27 | { 28 | int fd; 29 | char buf[] = "DUMMY DATA"; 30 | int n, c; 31 | int ret; 32 | 33 | if (argc < 2) { 34 | fprintf(stderr, "usage: %s \n", argv[0]); 35 | exit(EXIT_FAILURE); 36 | } 37 | 38 | ret = open(argv[1], O_RDWR); 39 | if (ret < 0) { 40 | perror("open"); 41 | exit(EXIT_FAILURE); 42 | } 43 | printf("file %s opened\n", argv[1]); 44 | fd = ret; 45 | 46 | for (c = 0; c < sizeof(buf); c += n) { 47 | ret = write(fd, buf + c, sizeof(buf) - c); 48 | if (ret < 0) { 49 | perror("write"); 50 | exit(EXIT_FAILURE); 51 | } 52 | n = ret; 53 | 54 | printf("wrote %d bytes into file %s\n", n, argv[1]); 55 | dump("data written are: ", buf + c, n); 56 | } 57 | 58 | for (c = 0; c < sizeof(buf); c += n) { 59 | ret = read(fd, buf, sizeof(buf)); 60 | if (ret == 0) { 61 | printf("read EOF\n"); 62 | break; 63 | } else if (ret < 0) { 64 | perror("read"); 65 | exit(EXIT_FAILURE); 66 | } 67 | n = ret; 68 | 69 | printf("read %d bytes from file %s\n", n, argv[1]); 70 | dump("data read are: ", buf, n); 71 | } 72 | 73 | close(fd); 74 | 75 | return 0; 76 | } 77 | -------------------------------------------------------------------------------- /Chapter03/modify_close_open_to_chrdev_test.patch: -------------------------------------------------------------------------------- 1 | diff --git a/chapter_3/chrdev_test.c b/chapter_3/chrdev_test.c 2 | index f72d4aa..7b5bc05 100644 3 | --- a/chapter_3/chrdev_test.c 4 | +++ b/chapter_3/chrdev_test.c 5 | @@ -55,6 +55,16 @@ int main(int argc, char *argv[]) 6 | dump("data written are: ", buf, n); 7 | } 8 | 9 | + close(fd); 10 | + 11 | + ret = open(argv[1], O_RDWR); 12 | + if (ret < 0) { 13 | + perror("open"); 14 | + exit(EXIT_FAILURE); 15 | + } 16 | + printf("file %s reopened\n", argv[1]); 17 | + fd = ret; 18 | + 19 | for (c = 0; c < sizeof(buf); c += n) { 20 | ret = read(fd, buf, sizeof(buf)); 21 | if (ret == 0) { 22 | -------------------------------------------------------------------------------- /Chapter04/chrdev/Makefile: -------------------------------------------------------------------------------- 1 | ifndef KERNEL_DIR 2 | $(error KERNEL_DIR must be set in the command line) 3 | endif 4 | PWD := $(shell pwd) 5 | ARCH ?= arm64 6 | CROSS_COMPILE ?= aarch64-linux-gnu- 7 | 8 | obj-m = chrdev.o 9 | obj-m += chrdev-req.o 10 | 11 | all: modules 12 | 13 | modules clean: 14 | make -C $(KERNEL_DIR) \ 15 | ARCH=$(ARCH) \ 16 | CROSS_COMPILE=$(CROSS_COMPILE) \ 17 | SUBDIRS=$(PWD) $@ 18 | -------------------------------------------------------------------------------- /Chapter04/chrdev/add_chrdev_devices.dts.patch: -------------------------------------------------------------------------------- 1 | diff --git a/arch/arm64/boot/dts/marvell/armada-3720-espressobin.dts b/arch/arm64/boot/dts/marvell/armada-3720-espressobin.dts 2 | index 3ab25ad402b9..71e7f4336a56 100644 3 | --- a/arch/arm64/boot/dts/marvell/armada-3720-espressobin.dts 4 | +++ b/arch/arm64/boot/dts/marvell/armada-3720-espressobin.dts 5 | @@ -41,6 +41,23 @@ 6 | 3300000 0x0>; 7 | enable-active-high; 8 | }; 9 | + 10 | + chrdev { 11 | + compatible = "ldddc,chrdev"; 12 | + #address-cells = <1>; 13 | + #size-cells = <0>; 14 | + 15 | + chrdev@2 { 16 | + label = "cdev-eeprom"; 17 | + reg = <2>; 18 | + }; 19 | + 20 | + chrdev@4 { 21 | + label = "cdev-rom"; 22 | + reg = <4>; 23 | + read-only; 24 | + }; 25 | + }; 26 | }; 27 | 28 | /* J9 */ 29 | -------------------------------------------------------------------------------- /Chapter04/chrdev/add_fixed_chrdev_devices.patch: -------------------------------------------------------------------------------- 1 | diff --git a/chapter_4/chrdev/chrdev-req.c b/chapter_4/chrdev/chrdev-req.c 2 | index 653176d..2048cd8 100644 3 | --- a/chapter_4/chrdev/chrdev-req.c 4 | +++ b/chapter_4/chrdev/chrdev-req.c 5 | @@ -9,10 +9,24 @@ 6 | #include 7 | #include 8 | #include 9 | +#include 10 | #include 11 | 12 | #include "chrdev.h" 13 | 14 | +/* 15 | + * Fixed data 16 | + */ 17 | + 18 | +static const struct chrdev_fixed_data chrdev_fd = { 19 | + .label = "cdev-fixed", 20 | +}; 21 | + 22 | +static const struct chrdev_fixed_data chrdev_fd_ro = { 23 | + .label = "cdev-fixedro", 24 | + .read_only = 1, 25 | +}; 26 | + 27 | /* 28 | * Platform driver stuff 29 | */ 30 | @@ -20,10 +34,26 @@ 31 | static int chrdev_req_probe(struct platform_device *pdev) 32 | { 33 | struct device *dev = &pdev->dev; 34 | + struct device_node *np = dev->of_node; 35 | + const struct chrdev_fixed_data *data = of_device_get_match_data(dev); 36 | struct fwnode_handle *child; 37 | struct module *owner = THIS_MODULE; 38 | int count, ret; 39 | 40 | + /* Check the chrdev device type */ 41 | + if (of_device_is_compatible(np, "ldddc,chrdev-fixed") || 42 | + of_device_is_compatible(np, "ldddc,chrdev-fixed_read-only")) { 43 | + ret = chrdev_device_register(data->label, 0, 44 | + data->read_only, owner, dev); 45 | + if (ret) 46 | + dev_err(dev, "unable to register fixed"); 47 | + 48 | + return ret; 49 | + } 50 | + 51 | + /* If we are not registering a fixed chrdev device then get 52 | + * the number of chrdev devices from DTS 53 | + */ 54 | count = device_get_child_node_count(dev); 55 | if (count == 0) 56 | return -ENODEV; 57 | @@ -65,9 +95,24 @@ static int chrdev_req_probe(struct platform_device *pdev) 58 | static int chrdev_req_remove(struct platform_device *pdev) 59 | { 60 | struct device *dev = &pdev->dev; 61 | + struct device_node *np = dev->of_node; 62 | + const struct chrdev_fixed_data *data = of_device_get_match_data(dev); 63 | struct fwnode_handle *child; 64 | int ret; 65 | 66 | + /* Check the chrdev device type */ 67 | + if (of_device_is_compatible(np, "ldddc,chrdev-fixed") || 68 | + of_device_is_compatible(np, "ldddc,chrdev-fixed_read-only")) { 69 | + ret = chrdev_device_unregister(data->label, 0); 70 | + if (ret) 71 | + dev_err(dev, "unable to unregister"); 72 | + 73 | + return ret; 74 | + } 75 | + 76 | + /* If we are not unregistering a fixed chrdev device then get 77 | + * the number of chrdev devices from DTS 78 | + */ 79 | device_for_each_child_node(dev, child) { 80 | const char *label; 81 | int id; 82 | @@ -98,6 +143,14 @@ static const struct of_device_id of_chrdev_req_match[] = { 83 | { 84 | .compatible = "ldddc,chrdev", 85 | }, 86 | + { 87 | + .compatible = "ldddc,chrdev-fixed", 88 | + .data = &chrdev_fd, 89 | + }, 90 | + { 91 | + .compatible = "ldddc,chrdev-fixed_read-only", 92 | + .data = &chrdev_fd_ro, 93 | + }, 94 | { /* sentinel */ } 95 | }; 96 | MODULE_DEVICE_TABLE(of, of_chrdev_req_match); 97 | diff --git a/chapter_4/chrdev/chrdev.h b/chapter_4/chrdev/chrdev.h 98 | index 9498467..0b5a334 100644 99 | --- a/chapter_4/chrdev/chrdev.h 100 | +++ b/chapter_4/chrdev/chrdev.h 101 | @@ -25,6 +25,12 @@ struct chrdev_device { 102 | struct device *dev; 103 | }; 104 | 105 | +struct chrdev_fixed_data { 106 | + char *label; 107 | + int read_only; 108 | +}; 109 | + 110 | + 111 | /* 112 | * Exported functions 113 | */ 114 | -------------------------------------------------------------------------------- /Chapter04/chrdev/add_sysfs_attrs_chrdev.patch: -------------------------------------------------------------------------------- 1 | diff --git a/chapter_4/chrdev/chrdev.c b/chapter_4/chrdev/chrdev.c 2 | index c9db2b6..2cb6a54 100644 3 | --- a/chapter_4/chrdev/chrdev.c 4 | +++ b/chapter_4/chrdev/chrdev.c 5 | @@ -19,6 +19,78 @@ static struct class *chrdev_class; 6 | 7 | struct chrdev_device chrdev_array[MAX_DEVICES]; 8 | 9 | +/* 10 | + * sysfs methods 11 | + */ 12 | + 13 | +static ssize_t id_show(struct device *dev, 14 | + struct device_attribute *attr, char *buf) 15 | +{ 16 | + struct chrdev_device *chrdev = dev_get_drvdata(dev); 17 | + 18 | + return sprintf(buf, "%d\n", chrdev->id); 19 | +} 20 | +static DEVICE_ATTR_RO(id); 21 | + 22 | +static ssize_t reset_to_store(struct device *dev, 23 | + struct device_attribute *attr, 24 | + const char *buf, size_t count) 25 | +{ 26 | + struct chrdev_device *chrdev = dev_get_drvdata(dev); 27 | + 28 | + if (count > BUF_LEN) 29 | + count = BUF_LEN; 30 | + memcpy(chrdev->buf, buf, count); 31 | + 32 | + return count; 33 | +} 34 | +static DEVICE_ATTR_WO(reset_to); 35 | + 36 | +static ssize_t read_only_show(struct device *dev, 37 | + struct device_attribute *attr, char *buf) 38 | +{ 39 | + struct chrdev_device *chrdev = dev_get_drvdata(dev); 40 | + 41 | + return sprintf(buf, "%d\n", chrdev->read_only); 42 | +} 43 | + 44 | +static ssize_t read_only_store(struct device *dev, 45 | + struct device_attribute *attr, 46 | + const char *buf, size_t count) 47 | +{ 48 | + struct chrdev_device *chrdev = dev_get_drvdata(dev); 49 | + int data, ret; 50 | + 51 | + ret = sscanf(buf, "%d", &data); 52 | + if (ret != 1) 53 | + return -EINVAL; 54 | + 55 | + chrdev->read_only = !!data; 56 | + 57 | + return count; 58 | +} 59 | +static DEVICE_ATTR_RW(read_only); 60 | + 61 | +/* 62 | + * Class attributes 63 | + */ 64 | + 65 | +static struct attribute *chrdev_attrs[] = { 66 | + &dev_attr_id.attr, 67 | + &dev_attr_reset_to.attr, 68 | + &dev_attr_read_only.attr, 69 | + NULL, 70 | +}; 71 | + 72 | +static const struct attribute_group chrdev_group = { 73 | + .attrs = chrdev_attrs, 74 | +}; 75 | + 76 | +static const struct attribute_group *chrdev_groups[] = { 77 | + &chrdev_group, 78 | + NULL, 79 | +}; 80 | + 81 | /* 82 | * Methods 83 | */ 84 | @@ -216,6 +288,7 @@ static int __init chrdev_init(void) 85 | pr_err("chrdev: failed to allocate class\n"); 86 | return -ENOMEM; 87 | } 88 | + chrdev_class->dev_groups = chrdev_groups; 89 | 90 | /* Allocate a region for character devices */ 91 | ret = alloc_chrdev_region(&chrdev_devt, 0, MAX_DEVICES, "chrdev"); 92 | -------------------------------------------------------------------------------- /Chapter04/chrdev/chrdev-fw.c: -------------------------------------------------------------------------------- 1 | /* 2 | * chrdev req 3 | */ 4 | 5 | #define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__ 6 | #include 7 | #include 8 | #include 9 | #include 10 | #include 11 | #include 12 | #include 13 | #include 14 | #include 15 | 16 | #include "chrdev.h" 17 | 18 | #define FIRMWARE_VER "1.0.0" 19 | #define FIRMWARE_NLEN 128 20 | 21 | static inline char printable(char c) 22 | { 23 | return (c < ' ') || (c > '~') ? '-' : c; 24 | } 25 | 26 | static void dump_data(const u8 *buf, size_t len) 27 | { 28 | int n, i; 29 | 30 | for (n = 0; n < len; n += i) { 31 | pr_info(""); 32 | for (i = 0; (i < 8) && (n + i < len); i++) 33 | pr_cont("%02x[%c] ", buf[n + i], printable(buf[n + i])); 34 | pr_cont("\n"); 35 | } 36 | } 37 | 38 | /* 39 | * Firmware loading callback 40 | */ 41 | 42 | static void chrdev_fw_cb(const struct firmware *fw, void *context) 43 | { 44 | struct device *dev = context; 45 | 46 | dev_info(dev, "firmware callback executed!\n"); 47 | if (!fw) { 48 | dev_err(dev, "unable to load firmware\n"); 49 | return; 50 | } 51 | 52 | dump_data(fw->data, fw->size); 53 | 54 | /* Firmware data has been read, now we can release it */ 55 | release_firmware(fw); 56 | } 57 | 58 | /* 59 | * Firmware loading functions 60 | */ 61 | 62 | static int chrdev_load_fw_wait(struct device *dev, const char *file) 63 | { 64 | char fw_name[FIRMWARE_NLEN]; 65 | const struct firmware *fw; 66 | int ret; 67 | 68 | /* Compose firmware filename */ 69 | if (strlen(file) > (128 - 6 - sizeof(FIRMWARE_VER))) 70 | return -EINVAL; 71 | sprintf(fw_name, "%s-%s.bin", file, FIRMWARE_VER); 72 | 73 | /* Do the firmware request */ 74 | ret = request_firmware(&fw, fw_name, dev); 75 | if (ret) { 76 | dev_err(dev, "unable to load firmware\n"); 77 | return ret; 78 | } 79 | 80 | dump_data(fw->data, fw->size); 81 | 82 | /* Firmware data has been read, now we can release it */ 83 | release_firmware(fw); 84 | 85 | return 0; 86 | } 87 | 88 | static int chrdev_load_fw_nowait(struct device *dev, const char *file) 89 | { 90 | char fw_name[FIRMWARE_NLEN]; 91 | int ret; 92 | 93 | /* Compose firmware filename */ 94 | if (strlen(file) > (128 - 6 - sizeof(FIRMWARE_VER))) 95 | return -EINVAL; 96 | sprintf(fw_name, "%s-%s.bin", file, FIRMWARE_VER); 97 | 98 | /* Do the firmware request */ 99 | ret = request_firmware_nowait(THIS_MODULE, false, fw_name, dev, 100 | GFP_KERNEL, dev, chrdev_fw_cb); 101 | if (ret) { 102 | dev_err(dev, 103 | "unable to register call back for firmware loading\n"); 104 | return ret; 105 | } 106 | 107 | return 0; 108 | } 109 | 110 | /* 111 | * Platform driver stuff 112 | */ 113 | 114 | static int chrdev_req_probe(struct platform_device *pdev) 115 | { 116 | struct device *dev = &pdev->dev; 117 | struct device_node *np = dev->of_node; 118 | struct fwnode_handle *fwh = of_fwnode_handle(np); 119 | struct module *owner = THIS_MODULE; 120 | const char *file; 121 | int ret = 0; 122 | 123 | /* Read device properties */ 124 | if (fwnode_property_read_string(fwh, "firmware", &file)) { 125 | dev_err(dev, "unable to get property \"firmware\"!"); 126 | return -EINVAL; 127 | } 128 | 129 | /* Load device firmware */ 130 | if (of_device_is_compatible(np, "ldddc,chrdev-fw_wait")) 131 | ret = chrdev_load_fw_wait(dev, file); 132 | else if (of_device_is_compatible(np, "ldddc,chrdev-fw_nowait")) 133 | ret = chrdev_load_fw_nowait(dev, file); 134 | if (ret) 135 | return ret; 136 | 137 | /* Register the new chr device */ 138 | ret = chrdev_device_register("chrdev-fw", 0, 0, owner, dev); 139 | if (ret) { 140 | dev_err(dev, "unable to register"); 141 | return ret; 142 | } 143 | 144 | return 0; 145 | } 146 | 147 | static int chrdev_req_remove(struct platform_device *pdev) 148 | { 149 | return chrdev_device_unregister("chrdev-fw", 0); 150 | } 151 | 152 | static const struct of_device_id of_chrdev_req_match[] = { 153 | { 154 | .compatible = "ldddc,chrdev-fw_wait", 155 | }, 156 | { 157 | .compatible = "ldddc,chrdev-fw_nowait", 158 | }, 159 | { /* sentinel */ } 160 | }; 161 | MODULE_DEVICE_TABLE(of, of_chrdev_req_match); 162 | 163 | static struct platform_driver chrdev_req_driver = { 164 | .probe = chrdev_req_probe, 165 | .remove = chrdev_req_remove, 166 | .driver = { 167 | .name = "chrdev-fw", 168 | .of_match_table = of_chrdev_req_match, 169 | }, 170 | }; 171 | module_platform_driver(chrdev_req_driver); 172 | 173 | MODULE_LICENSE("GPL"); 174 | MODULE_AUTHOR("Rodolfo Giometti"); 175 | MODULE_DESCRIPTION("chrdev firmware"); 176 | -------------------------------------------------------------------------------- /Chapter04/chrdev/chrdev-req.c: -------------------------------------------------------------------------------- 1 | /* 2 | * chrdev req 3 | */ 4 | 5 | #define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__ 6 | #include 7 | #include 8 | #include 9 | #include 10 | #include 11 | #include 12 | #include 13 | 14 | #include "chrdev.h" 15 | 16 | /* 17 | * Platform driver stuff 18 | */ 19 | 20 | static int chrdev_req_probe(struct platform_device *pdev) 21 | { 22 | struct device *dev = &pdev->dev; 23 | struct fwnode_handle *child; 24 | struct module *owner = THIS_MODULE; 25 | int count, ret; 26 | 27 | count = device_get_child_node_count(dev); 28 | if (count == 0) 29 | return -ENODEV; 30 | if (count > MAX_DEVICES) 31 | return -ENOMEM; 32 | 33 | device_for_each_child_node(dev, child) { 34 | const char *label; 35 | unsigned int id, ro; 36 | 37 | /* 38 | * Get device's properties 39 | */ 40 | 41 | if (fwnode_property_present(child, "reg")) { 42 | fwnode_property_read_u32(child, "reg", &id); 43 | } else { 44 | dev_err(dev, "property \"reg\" not present! Skipped"); 45 | continue; 46 | } 47 | if (fwnode_property_present(child, "label")) { 48 | fwnode_property_read_string(child, "label", &label); 49 | } else { 50 | dev_err(dev, "property \"label\" not present! Skipped"); 51 | continue; 52 | } 53 | ro = fwnode_property_present(child, "read-only"); 54 | 55 | /* Register the new chr device */ 56 | ret = chrdev_device_register(label, id, ro, owner, dev); 57 | if (ret) { 58 | dev_err(dev, "unable to register"); 59 | } 60 | } 61 | 62 | return 0; 63 | } 64 | 65 | static int chrdev_req_remove(struct platform_device *pdev) 66 | { 67 | struct device *dev = &pdev->dev; 68 | struct fwnode_handle *child; 69 | int ret; 70 | 71 | device_for_each_child_node(dev, child) { 72 | const char *label; 73 | int id; 74 | 75 | /* 76 | * Get device's properties 77 | */ 78 | 79 | if (fwnode_property_present(child, "reg")) 80 | fwnode_property_read_u32(child, "reg", &id); 81 | else 82 | BUG(); 83 | if (fwnode_property_present(child, "label")) 84 | fwnode_property_read_string(child, "label", &label); 85 | else 86 | BUG(); 87 | 88 | /* Register the new chr device */ 89 | ret = chrdev_device_unregister(label, id); 90 | if (ret) 91 | dev_err(dev, "unable to unregister"); 92 | } 93 | 94 | return 0; 95 | } 96 | 97 | static const struct of_device_id of_chrdev_req_match[] = { 98 | { 99 | .compatible = "ldddc,chrdev", 100 | }, 101 | { /* sentinel */ } 102 | }; 103 | MODULE_DEVICE_TABLE(of, of_chrdev_req_match); 104 | 105 | static struct platform_driver chrdev_req_driver = { 106 | .probe = chrdev_req_probe, 107 | .remove = chrdev_req_remove, 108 | .driver = { 109 | .name = "chrdev-req", 110 | .of_match_table = of_chrdev_req_match, 111 | }, 112 | }; 113 | module_platform_driver(chrdev_req_driver); 114 | 115 | MODULE_LICENSE("GPL"); 116 | MODULE_AUTHOR("Rodolfo Giometti"); 117 | MODULE_DESCRIPTION("chrdev request"); 118 | -------------------------------------------------------------------------------- /Chapter04/chrdev/chrdev.c: -------------------------------------------------------------------------------- 1 | /* 2 | * chrdev 3 | */ 4 | 5 | #define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__ 6 | #include 7 | #include 8 | #include 9 | #include 10 | 11 | #include "chrdev.h" 12 | 13 | /* 14 | * Local variables 15 | */ 16 | 17 | static dev_t chrdev_devt; 18 | static struct class *chrdev_class; 19 | 20 | struct chrdev_device chrdev_array[MAX_DEVICES]; 21 | 22 | /* 23 | * Methods 24 | */ 25 | 26 | static ssize_t chrdev_read(struct file *filp, 27 | char __user *buf, size_t count, loff_t *ppos) 28 | { 29 | struct chrdev_device *chrdev = filp->private_data; 30 | int ret; 31 | 32 | dev_info(chrdev->dev, "should read %ld bytes (*ppos=%lld)\n", 33 | count, *ppos); 34 | 35 | /* Check for end-of-buffer */ 36 | if (*ppos + count >= BUF_LEN) 37 | count = BUF_LEN - *ppos; 38 | 39 | /* Return data to the user space */ 40 | ret = copy_to_user(buf, chrdev->buf + *ppos, count); 41 | if (ret < 0) 42 | return -EFAULT; 43 | 44 | *ppos += count; 45 | dev_info(chrdev->dev, "return %ld bytes (*ppos=%lld)\n", count, *ppos); 46 | 47 | return count; 48 | } 49 | 50 | static ssize_t chrdev_write(struct file *filp, 51 | const char __user *buf, size_t count, loff_t *ppos) 52 | { 53 | struct chrdev_device *chrdev = filp->private_data; 54 | int ret; 55 | 56 | dev_info(chrdev->dev, "should write %ld bytes (*ppos=%lld)\n", 57 | count, *ppos); 58 | 59 | if (chrdev->read_only) 60 | return -EINVAL; 61 | 62 | /* Check for end-of-buffer */ 63 | if (*ppos + count >= BUF_LEN) 64 | count = BUF_LEN - *ppos; 65 | 66 | /* Get data from the user space */ 67 | ret = copy_from_user(chrdev->buf + *ppos, buf, count); 68 | if (ret < 0) 69 | return -EFAULT; 70 | 71 | *ppos += count; 72 | dev_info(chrdev->dev, "got %ld bytes (*ppos=%lld)\n", count, *ppos); 73 | 74 | return count; 75 | } 76 | 77 | static int chrdev_open(struct inode *inode, struct file *filp) 78 | { 79 | struct chrdev_device *chrdev = container_of(inode->i_cdev, 80 | struct chrdev_device, cdev); 81 | filp->private_data = chrdev; 82 | kobject_get(&chrdev->dev->kobj); 83 | 84 | dev_info(chrdev->dev, "chrdev (id=%d) opened\n", chrdev->id); 85 | 86 | return 0; 87 | } 88 | 89 | static int chrdev_release(struct inode *inode, struct file *filp) 90 | { 91 | struct chrdev_device *chrdev = container_of(inode->i_cdev, 92 | struct chrdev_device, cdev); 93 | kobject_put(&chrdev->dev->kobj); 94 | filp->private_data = NULL; 95 | 96 | dev_info(chrdev->dev, "chrdev (id=%d) released\n", chrdev->id); 97 | 98 | return 0; 99 | } 100 | 101 | static const struct file_operations chrdev_fops = { 102 | .owner = THIS_MODULE, 103 | .read = chrdev_read, 104 | .write = chrdev_write, 105 | .open = chrdev_open, 106 | .release = chrdev_release 107 | }; 108 | 109 | /* 110 | * Exported functions 111 | */ 112 | 113 | int chrdev_device_register(const char *label, unsigned int id, 114 | unsigned int read_only, 115 | struct module *owner, struct device *parent) 116 | { 117 | struct chrdev_device *chrdev; 118 | dev_t devt; 119 | int ret; 120 | 121 | /* First check if we are allocating a valid device... */ 122 | if (id >= MAX_DEVICES) { 123 | pr_err("invalid id %d\n", id); 124 | return -EINVAL; 125 | } 126 | chrdev = &chrdev_array[id]; 127 | 128 | /* ... then check if we have not busy id */ 129 | if (chrdev->busy) { 130 | pr_err("id %d\n is busy", id); 131 | return -EBUSY; 132 | } 133 | 134 | /* Create the device and initialize its data */ 135 | cdev_init(&chrdev->cdev, &chrdev_fops); 136 | chrdev->cdev.owner = owner; 137 | 138 | devt = MKDEV(MAJOR(chrdev_devt), id); 139 | ret = cdev_add(&chrdev->cdev, devt, 1); 140 | if (ret) { 141 | pr_err("failed to add char device %s at %d:%d\n", 142 | label, MAJOR(chrdev_devt), id); 143 | return ret; 144 | } 145 | 146 | chrdev->dev = device_create(chrdev_class, parent, devt, chrdev, 147 | "%s@%d", label, id); 148 | if (IS_ERR(chrdev->dev)) { 149 | pr_err("unable to create device %s\n", label); 150 | ret = PTR_ERR(chrdev->dev); 151 | goto del_cdev; 152 | } 153 | dev_set_drvdata(chrdev->dev, chrdev); 154 | 155 | /* Init the chrdev data */ 156 | chrdev->id = id; 157 | chrdev->read_only = read_only; 158 | chrdev->busy = 1; 159 | strncpy(chrdev->label, label, NAME_LEN); 160 | memset(chrdev->buf, 0, BUF_LEN); 161 | 162 | dev_info(chrdev->dev, "chrdev %s with id %d added\n", label, id); 163 | 164 | return 0; 165 | 166 | del_cdev: 167 | cdev_del(&chrdev->cdev); 168 | 169 | return ret; 170 | } 171 | EXPORT_SYMBOL(chrdev_device_register); 172 | 173 | int chrdev_device_unregister(const char *label, unsigned int id) 174 | { 175 | struct chrdev_device *chrdev; 176 | 177 | /* First check if we are deallocating a valid device... */ 178 | if (id >= MAX_DEVICES) { 179 | pr_err("invalid id %d\n", id); 180 | return -EINVAL; 181 | } 182 | chrdev = &chrdev_array[id]; 183 | 184 | /* ... then check if device is actualy allocated */ 185 | if (!chrdev->busy || strcmp(chrdev->label, label)) { 186 | pr_err("id %d is not busy or label %s is not known\n", 187 | id, label); 188 | return -EINVAL; 189 | } 190 | 191 | /* Deinit the chrdev data */ 192 | chrdev->id = 0; 193 | chrdev->busy = 0; 194 | 195 | dev_info(chrdev->dev, "chrdev %s with id %d removed\n", label, id); 196 | 197 | /* Dealocate the device */ 198 | device_destroy(chrdev_class, chrdev->dev->devt); 199 | cdev_del(&chrdev->cdev); 200 | 201 | return 0; 202 | } 203 | EXPORT_SYMBOL(chrdev_device_unregister); 204 | 205 | /* 206 | * Module stuff 207 | */ 208 | 209 | static int __init chrdev_init(void) 210 | { 211 | int ret; 212 | 213 | /* Create the new class for the chrdev devices */ 214 | chrdev_class = class_create(THIS_MODULE, "chrdev"); 215 | if (!chrdev_class) { 216 | pr_err("chrdev: failed to allocate class\n"); 217 | return -ENOMEM; 218 | } 219 | 220 | /* Allocate a region for character devices */ 221 | ret = alloc_chrdev_region(&chrdev_devt, 0, MAX_DEVICES, "chrdev"); 222 | if (ret < 0) { 223 | pr_err("failed to allocate char device region\n"); 224 | goto remove_class; 225 | } 226 | 227 | pr_info("got major %d\n", MAJOR(chrdev_devt)); 228 | 229 | return 0; 230 | 231 | remove_class: 232 | class_destroy(chrdev_class); 233 | 234 | return ret; 235 | } 236 | 237 | static void __exit chrdev_exit(void) 238 | { 239 | unregister_chrdev_region(chrdev_devt, MAX_DEVICES); 240 | class_destroy(chrdev_class); 241 | } 242 | 243 | module_init(chrdev_init); 244 | module_exit(chrdev_exit); 245 | 246 | MODULE_LICENSE("GPL"); 247 | MODULE_AUTHOR("Rodolfo Giometti"); 248 | MODULE_DESCRIPTION("chardev"); 249 | -------------------------------------------------------------------------------- /Chapter04/chrdev/chrdev.h: -------------------------------------------------------------------------------- 1 | /* 2 | * Chrdev include file 3 | */ 4 | 5 | #include 6 | 7 | #define MAX_DEVICES 8 8 | #define NAME_LEN 32 9 | #define BUF_LEN 300 10 | 11 | /* 12 | * Chrdev basic structs 13 | */ 14 | 15 | /* Main struct */ 16 | struct chrdev_device { 17 | char label[NAME_LEN]; 18 | unsigned int busy : 1; 19 | char buf[BUF_LEN]; 20 | int read_only; 21 | 22 | unsigned int id; 23 | struct module *owner; 24 | struct cdev cdev; 25 | struct device *dev; 26 | }; 27 | 28 | /* 29 | * Exported functions 30 | */ 31 | 32 | #define to_class_dev(obj) container_of((obj), struct class_device, kobj) 33 | #define to_chrdev_device(obj) container_of((obj), struct chrdev_device, class) 34 | 35 | extern int chrdev_device_register(const char *label, unsigned int id, 36 | unsigned int read_only, 37 | struct module *owner, struct device *parent); 38 | extern int chrdev_device_unregister(const char *label, unsigned int id); 39 | -------------------------------------------------------------------------------- /Chapter04/get_dt_data/Makefile: -------------------------------------------------------------------------------- 1 | ifndef KERNEL_DIR 2 | $(error KERNEL_DIR must be set in the command line) 3 | endif 4 | PWD := $(shell pwd) 5 | ARCH ?= arm64 6 | CROSS_COMPILE ?= aarch64-linux-gnu- 7 | 8 | # This specifies the kernel module to be compiled 9 | obj-m += get_dt_data.o 10 | 11 | # The default action 12 | all: modules 13 | 14 | # The main tasks 15 | modules clean: 16 | make -C $(KERNEL_DIR) \ 17 | ARCH=$(ARCH) \ 18 | CROSS_COMPILE=$(CROSS_COMPILE) \ 19 | SUBDIRS=$(PWD) $@ 20 | -------------------------------------------------------------------------------- /Chapter04/get_dt_data/get_dt_data.c: -------------------------------------------------------------------------------- 1 | /* 2 | * Module to inspect device tree from the kernel 3 | */ 4 | 5 | #define pr_fmt(fmt) "%s: " fmt, KBUILD_MODNAME 6 | #include 7 | #include 8 | #include 9 | 10 | #define PATH_DEFAULT "/" 11 | static char *path = PATH_DEFAULT; 12 | module_param(path, charp, S_IRUSR | S_IWUSR); 13 | MODULE_PARM_DESC(path, "a device tree pathname " \ 14 | "(default is \"" PATH_DEFAULT "\")"); 15 | 16 | /* 17 | * Local functions 18 | */ 19 | 20 | static void print_property_u32(struct device_node *node, const char *name) 21 | { 22 | u32 val32; 23 | if (of_property_read_u32(node, name, &val32) == 0) 24 | pr_info(" \%s = %d\n", name, val32); 25 | } 26 | 27 | static void print_property_string(struct device_node *node, const char *name) 28 | { 29 | const char *str; 30 | if (of_property_read_string(node, name, &str) == 0) 31 | pr_info(" \%s = %s\n", name, str); 32 | } 33 | 34 | static void print_main_prop(struct device_node *node) 35 | { 36 | pr_info("+ node = %s\n", node->full_name); 37 | print_property_u32(node, "#address-cells"); 38 | print_property_u32(node, "#size-cells"); 39 | print_property_u32(node, "reg"); 40 | print_property_string(node, "name"); 41 | print_property_string(node, "compatible"); 42 | print_property_string(node, "status"); 43 | } 44 | 45 | /* 46 | * Init & exit stuff 47 | */ 48 | 49 | static int __init get_dt_data_init(void) 50 | { 51 | struct device_node *node, *child; 52 | struct property *prop; 53 | 54 | pr_info("path = \"%s\"\n", path); 55 | 56 | /* Find node by its pathname */ 57 | node = of_find_node_by_path(path); 58 | if (!node) { 59 | pr_err("failed to find device-tree node \"%s\"\n", path); 60 | return -ENODEV; 61 | } 62 | pr_info("device-tree node found!\n"); 63 | 64 | pr_info("now getting main properties...\n"); 65 | print_main_prop(node); 66 | 67 | pr_info("now move through all properties...\n"); 68 | for_each_property_of_node(node, prop) 69 | pr_info("-> %s\n", prop->name); 70 | 71 | /* Move through node's children... */ 72 | pr_info("Now move through children...\n"); 73 | for_each_child_of_node(node, child) 74 | print_main_prop(child); 75 | 76 | /* Force module unloading... */ 77 | return -EINVAL; 78 | } 79 | 80 | static void __exit get_dt_data_exit(void) 81 | { 82 | /* nop */ 83 | } 84 | 85 | module_init(get_dt_data_init); 86 | module_exit(get_dt_data_exit); 87 | 88 | MODULE_LICENSE("GPL"); 89 | MODULE_AUTHOR("Rodolfo Giometti"); 90 | MODULE_DESCRIPTION("Module to inspect device tree from the kernel"); 91 | MODULE_VERSION("0.1"); 92 | -------------------------------------------------------------------------------- /Chapter04/simple_platform/.gitignore: -------------------------------------------------------------------------------- 1 | simple_platform-reverted.dts 2 | simple_platform.dtb 3 | -------------------------------------------------------------------------------- /Chapter04/simple_platform/simple_platform.dts: -------------------------------------------------------------------------------- 1 | /dts-v1/; 2 | 3 | / { 4 | model = "fsl,mpc8572ds"; 5 | compatible = "fsl,mpc8572ds"; 6 | #address-cells = <1>; 7 | #size-cells = <1>; 8 | 9 | chosen { 10 | bootargs = "root=/dev/sda2"; 11 | }; 12 | 13 | aliases { 14 | tty0 = &serial0; 15 | }; 16 | 17 | cpus { 18 | #address-cells = <1>; 19 | #size-cells = <0>; 20 | 21 | cpu@0 { 22 | device_type = "cpu"; 23 | reg = <0>; 24 | timebase-frequency=<825000000>; 25 | clock-frequency=<825000000>; 26 | }; 27 | 28 | cpu@1 { 29 | device_type = "cpu"; 30 | reg = <1>; 31 | timebase-frequency=<825000000>; 32 | clock-frequency=<825000000>; 33 | }; 34 | 35 | 36 | }; 37 | 38 | memory@0 { 39 | device_type = "memory"; 40 | reg = <0x0 0x20000000>; 41 | }; 42 | 43 | clocks { 44 | #address-cells = <1>; 45 | #size-cells = <0>; 46 | 47 | osc: osc { 48 | compatible = "fixed-clock"; 49 | #clock-cells = <0>; 50 | clock-frequency = <33000000>; 51 | }; 52 | }; 53 | 54 | soc@80000000 { 55 | compatible = "fsl,mpc5121-immr"; 56 | #address-cells = <1>; 57 | #size-cells = <1>; 58 | device_type = "soc"; 59 | ranges = <0x0 0x80000000 0x400000>; 60 | reg = <0x80000000 0x400000>; 61 | bus-frequency = <66666666>; 62 | 63 | ipic: interrupt-controller@c00 { 64 | compatible = "fsl,mpc5121-ipic", "fsl,ipic"; 65 | interrupt-controller; 66 | #address-cells = <0>; 67 | #interrupt-cells = <2>; 68 | reg = <0xc00 0x100>; 69 | }; 70 | 71 | clks: clock@f00 { 72 | compatible = "fsl,mpc5121-clock"; 73 | reg = <0xf00 0x100>; 74 | #clock-cells = <1>; 75 | clocks = <&osc>; 76 | clock-names = "osc"; 77 | }; 78 | 79 | serial0: serial@11100 { 80 | compatible = "fsl,mpc5125-psc-uart", "fsl,mpc5125-psc"; 81 | reg = <0x11100 0x100>; 82 | interrupt-parent = <&ipic>; 83 | interrupts = <40 0x8>; 84 | fsl,rx-fifo-size = <16>; 85 | fsl,tx-fifo-size = <16>; 86 | clocks = <&clks 47>, <&clks 34>; 87 | clock-names = "ipg", "mclk"; 88 | }; 89 | }; 90 | }; 91 | -------------------------------------------------------------------------------- /Chapter05/add_irqtest_module.patch: -------------------------------------------------------------------------------- 1 | diff --git a/arch/arm64/boot/dts/marvell/armada-3720-espressobin.dts b/arch/arm64/boot/dts/marvell/armada-3720-espressobin.dts 2 | index 3ab25ad402b9..cf4831f3d7cc 100644 3 | --- a/arch/arm64/boot/dts/marvell/armada-3720-espressobin.dts 4 | +++ b/arch/arm64/boot/dts/marvell/armada-3720-espressobin.dts 5 | @@ -41,6 +41,12 @@ 6 | 3300000 0x0>; 7 | enable-active-high; 8 | }; 9 | + 10 | + irqtest { 11 | + compatible = "ldddc,irqtest"; 12 | + 13 | + gpios = <&gpiosb 20 GPIO_ACTIVE_LOW>; 14 | + }; 15 | }; 16 | 17 | /* J9 */ 18 | diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig 19 | index 3726eacdf65d..da4ab76114ab 100644 20 | --- a/drivers/misc/Kconfig 21 | +++ b/drivers/misc/Kconfig 22 | @@ -527,4 +527,11 @@ source "drivers/misc/echo/Kconfig" 23 | source "drivers/misc/cxl/Kconfig" 24 | source "drivers/misc/ocxl/Kconfig" 25 | source "drivers/misc/cardreader/Kconfig" 26 | + 27 | +config IRQTEST_CODE 28 | + tristate "Simple IRQ test" 29 | + default n 30 | + ---help--- 31 | + The irqtest module. 32 | + 33 | endmenu 34 | diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile 35 | index af22bbc3d00c..f74099e75af3 100644 36 | --- a/drivers/misc/Makefile 37 | +++ b/drivers/misc/Makefile 38 | @@ -58,3 +58,4 @@ obj-$(CONFIG_ASPEED_LPC_SNOOP) += aspeed-lpc-snoop.o 39 | obj-$(CONFIG_PCI_ENDPOINT_TEST) += pci_endpoint_test.o 40 | obj-$(CONFIG_OCXL) += ocxl/ 41 | obj-$(CONFIG_MISC_RTSX) += cardreader/ 42 | +obj-$(CONFIG_IRQTEST_CODE) += irqtest.o 43 | diff --git a/drivers/misc/irqtest.c b/drivers/misc/irqtest.c 44 | new file mode 100644 45 | index 000000000000..186b4bbb23fb 46 | --- /dev/null 47 | +++ b/drivers/misc/irqtest.c 48 | @@ -0,0 +1,125 @@ 49 | +/* 50 | + * irqtest 51 | + */ 52 | + 53 | +#define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__ 54 | +#include 55 | +#include 56 | +#include 57 | +#include 58 | +#include 59 | +#include 60 | +#include 61 | +#include 62 | +#include 63 | +#include 64 | +#include 65 | + 66 | +/* 67 | + * Module data 68 | + */ 69 | + 70 | +static struct irqtest_data { 71 | + int irq; 72 | + unsigned int pin; 73 | + struct device *dev; 74 | +} irqinfo; 75 | + 76 | +/* 77 | + * The interrupt handler 78 | + */ 79 | + 80 | +static irqreturn_t irqtest_interrupt(int irq, void *dev_id) 81 | +{ 82 | + struct irqtest_data *info = dev_id; 83 | + struct device *dev = info->dev; 84 | + 85 | + dev_info(dev, "interrupt occurred on IRQ %d\n", irq); 86 | + 87 | + return IRQ_HANDLED; 88 | +} 89 | + 90 | +/* 91 | + * Probe/remove functions 92 | + */ 93 | + 94 | +static int irqtest_probe(struct platform_device *pdev) 95 | +{ 96 | + struct device *dev = &pdev->dev; 97 | + struct device_node *np = dev->of_node; 98 | + int ret; 99 | + 100 | + /* Read gpios property (just the first entry) */ 101 | + ret = of_get_gpio(np, 0); 102 | + if (ret < 0) { 103 | + dev_err(dev, "failed to get GPIO from device tree\n"); 104 | + return ret; 105 | + } 106 | + irqinfo.pin = ret; 107 | + dev_info(dev, "got GPIO %u from DTS\n", irqinfo.pin); 108 | + 109 | + /* Now request the GPIO and set the line as an input */ 110 | + ret = devm_gpio_request(dev, irqinfo.pin, "irqtest"); 111 | + if (ret) { 112 | + dev_err(dev, "failed to request GPIO %u\n", irqinfo.pin); 113 | + return ret; 114 | + } 115 | + ret = gpio_direction_input(irqinfo.pin); 116 | + if (ret) { 117 | + dev_err(dev, "failed to set pin input direction\n"); 118 | + return -EINVAL; 119 | + } 120 | + 121 | + /* Now ask to the kernel to convert GPIO line into an IRQ line */ 122 | + ret = gpio_to_irq(irqinfo.pin); 123 | + if (ret < 0) { 124 | + dev_err(dev, "failed to map GPIO to IRQ!\n"); 125 | + return -EINVAL; 126 | + } 127 | + irqinfo.irq = ret; 128 | + dev_info(dev, "GPIO %u correspond to IRQ %d\n", 129 | + irqinfo.pin, irqinfo.irq); 130 | + 131 | + /* Request IRQ line and setup corresponding handler */ 132 | + irqinfo.dev = dev; 133 | + ret = request_irq(irqinfo.irq, irqtest_interrupt, 0, 134 | + "irqtest", &irqinfo); 135 | + if (ret) { 136 | + dev_err(dev, "cannot register IRQ %d\n", irqinfo.irq); 137 | + return -EIO; 138 | + } 139 | + dev_info(dev, "interrupt handler for IRQ %d is now ready!\n", 140 | + irqinfo.irq); 141 | + 142 | + return 0; 143 | +} 144 | + 145 | +static int irqtest_remove(struct platform_device *pdev) 146 | +{ 147 | + struct device *dev = &pdev->dev; 148 | + 149 | + free_irq(irqinfo.irq, &irqinfo); 150 | + dev_info(dev, "IRQ %d is now unmanaged!\n", irqinfo.irq); 151 | + 152 | + return 0; 153 | +} 154 | + 155 | +static const struct of_device_id irqtest_dt_ids[] = { 156 | + { .compatible = "ldddc,irqtest", }, 157 | + { /* sentinel */ } 158 | +}; 159 | +MODULE_DEVICE_TABLE(of, irqtest_dt_ids); 160 | + 161 | +static struct platform_driver irqtest_driver = { 162 | + .probe = irqtest_probe, 163 | + .remove = irqtest_remove, 164 | + .driver = { 165 | + .name = "irqtest", 166 | + .of_match_table = irqtest_dt_ids, 167 | + }, 168 | +}; 169 | + 170 | +module_platform_driver(irqtest_driver); 171 | +MODULE_AUTHOR("Rodolfo Giometti"); 172 | +MODULE_DESCRIPTION("IRQ test module"); 173 | +MODULE_LICENSE("GPL"); 174 | -------------------------------------------------------------------------------- /Chapter05/add_tasklet_2_to_irqtest_module.patch: -------------------------------------------------------------------------------- 1 | diff --git a/drivers/misc/irqtest.c b/drivers/misc/irqtest.c 2 | index 186b4bbb23fb..bae3e8af31f1 100644 3 | --- a/drivers/misc/irqtest.c 4 | +++ b/drivers/misc/irqtest.c 5 | @@ -23,12 +23,21 @@ static struct irqtest_data { 6 | int irq; 7 | unsigned int pin; 8 | struct device *dev; 9 | + struct tasklet_struct task; 10 | } irqinfo; 11 | 12 | /* 13 | - * The interrupt handler 14 | + * The interrupt handlers 15 | */ 16 | 17 | +static void irqtest_tasklet_handler(unsigned long flag) 18 | +{ 19 | + struct irqtest_data *info = (struct irqtest_data *) flag; 20 | + struct device *dev = info->dev; 21 | + 22 | + dev_info(dev, "tasklet executed after IRQ %d", info->irq); 23 | +} 24 | + 25 | static irqreturn_t irqtest_interrupt(int irq, void *dev_id) 26 | { 27 | struct irqtest_data *info = dev_id; 28 | @@ -36,6 +45,8 @@ static irqreturn_t irqtest_interrupt(int irq, void *dev_id) 29 | 30 | dev_info(dev, "interrupt occurred on IRQ %d\n", irq); 31 | 32 | + tasklet_schedule(&info->task); 33 | + 34 | return IRQ_HANDLED; 35 | } 36 | 37 | @@ -80,6 +91,10 @@ static int irqtest_probe(struct platform_device *pdev) 38 | dev_info(dev, "GPIO %u correspond to IRQ %d\n", 39 | irqinfo.pin, irqinfo.irq); 40 | 41 | + /* Create our tasklet */ 42 | + tasklet_init(&irqinfo.task, irqtest_tasklet_handler, 43 | + (unsigned long) &irqinfo); 44 | + 45 | /* Request IRQ line and setup corresponding handler */ 46 | irqinfo.dev = dev; 47 | ret = request_irq(irqinfo.irq, irqtest_interrupt, 0, 48 | @@ -98,6 +113,7 @@ static int irqtest_remove(struct platform_device *pdev) 49 | { 50 | struct device *dev = &pdev->dev; 51 | 52 | + tasklet_kill(&irqinfo.task); 53 | free_irq(irqinfo.irq, &irqinfo); 54 | dev_info(dev, "IRQ %d is now unmanaged!\n", irqinfo.irq); 55 | 56 | -------------------------------------------------------------------------------- /Chapter05/add_tasklet_to_irqtest_module.patch: -------------------------------------------------------------------------------- 1 | diff --git a/drivers/misc/irqtest.c b/drivers/misc/irqtest.c 2 | index 186b4bbb23fb..248bcbb0ae72 100644 3 | --- a/drivers/misc/irqtest.c 4 | +++ b/drivers/misc/irqtest.c 5 | @@ -26,9 +26,19 @@ static struct irqtest_data { 6 | } irqinfo; 7 | 8 | /* 9 | - * The interrupt handler 10 | + * The interrupt handlers 11 | */ 12 | 13 | +static void irqtest_tasklet_handler(unsigned long flag) 14 | +{ 15 | + struct irqtest_data *info = (struct irqtest_data *) flag; 16 | + struct device *dev = info->dev; 17 | + 18 | + dev_info(dev, "tasklet executed after IRQ %d", info->irq); 19 | +} 20 | +DECLARE_TASKLET(irqtest_tasklet, irqtest_tasklet_handler, 21 | + (unsigned long) &irqinfo); 22 | + 23 | static irqreturn_t irqtest_interrupt(int irq, void *dev_id) 24 | { 25 | struct irqtest_data *info = dev_id; 26 | @@ -36,6 +46,8 @@ static irqreturn_t irqtest_interrupt(int irq, void *dev_id) 27 | 28 | dev_info(dev, "interrupt occurred on IRQ %d\n", irq); 29 | 30 | + tasklet_schedule(&irqtest_tasklet); 31 | + 32 | return IRQ_HANDLED; 33 | } 34 | 35 | @@ -98,6 +110,7 @@ static int irqtest_remove(struct platform_device *pdev) 36 | { 37 | struct device *dev = &pdev->dev; 38 | 39 | + tasklet_kill(&irqtest_tasklet); 40 | free_irq(irqinfo.irq, &irqinfo); 41 | dev_info(dev, "IRQ %d is now unmanaged!\n", irqinfo.irq); 42 | 43 | -------------------------------------------------------------------------------- /Chapter05/add_workqueue_2_to_irqtest_module.patch: -------------------------------------------------------------------------------- 1 | diff --git a/drivers/misc/irqtest.c b/drivers/misc/irqtest.c 2 | index 1cb8636599d7..aeab4cc84e87 100644 3 | --- a/drivers/misc/irqtest.c 4 | +++ b/drivers/misc/irqtest.c 5 | @@ -14,6 +14,7 @@ 6 | #include 7 | #include 8 | #include 9 | +#include 10 | 11 | /* 12 | * Module data 13 | @@ -23,12 +24,35 @@ static struct irqtest_data { 14 | int irq; 15 | unsigned int pin; 16 | struct device *dev; 17 | + struct work_struct work; 18 | + struct delayed_work dwork; 19 | } irqinfo; 20 | 21 | /* 22 | - * The interrupt handler 23 | + * The interrupt handlers 24 | */ 25 | 26 | +static void irqtest_dwork_handler(struct work_struct *ptr) 27 | +{ 28 | + struct irqtest_data *info = container_of(ptr, struct irqtest_data, 29 | + dwork.work); 30 | + struct device *dev = info->dev; 31 | + 32 | + dev_info(dev, "delayed work executed after work"); 33 | +} 34 | + 35 | +static void irqtest_work_handler(struct work_struct *ptr) 36 | +{ 37 | + struct irqtest_data *info = container_of(ptr, struct irqtest_data, 38 | + work); 39 | + struct device *dev = info->dev; 40 | + 41 | + dev_info(dev, "work executed after IRQ %d", info->irq); 42 | + 43 | + /* Schedule the delayed work after 2 seconds */ 44 | + schedule_delayed_work(&info->dwork, 2*HZ); 45 | +} 46 | + 47 | static irqreturn_t irqtest_interrupt(int irq, void *dev_id) 48 | { 49 | struct irqtest_data *info = dev_id; 50 | @@ -36,6 +60,8 @@ static irqreturn_t irqtest_interrupt(int irq, void *dev_id) 51 | 52 | dev_info(dev, "interrupt occurred on IRQ %d\n", irq); 53 | 54 | + schedule_work(&info->work); 55 | + 56 | return IRQ_HANDLED; 57 | } 58 | 59 | @@ -80,6 +106,10 @@ static int irqtest_probe(struct platform_device *pdev) 60 | dev_info(dev, "GPIO %u correspond to IRQ %d\n", 61 | irqinfo.pin, irqinfo.irq); 62 | 63 | + /* Init works */ 64 | + INIT_WORK(&irqinfo.work, irqtest_work_handler); 65 | + INIT_DELAYED_WORK(&irqinfo.dwork, irqtest_dwork_handler); 66 | + 67 | /* Request IRQ line and setup corresponding handler */ 68 | irqinfo.dev = dev; 69 | ret = request_irq(irqinfo.irq, irqtest_interrupt, 0, 70 | @@ -98,6 +128,8 @@ static int irqtest_remove(struct platform_device *pdev) 71 | { 72 | struct device *dev = &pdev->dev; 73 | 74 | + cancel_work_sync(&irqinfo.work); 75 | + cancel_delayed_work_sync(&irqinfo.dwork); 76 | free_irq(irqinfo.irq, &irqinfo); 77 | dev_info(dev, "IRQ %d is now unmanaged!\n", irqinfo.irq); 78 | 79 | -------------------------------------------------------------------------------- /Chapter05/add_workqueue_to_irqtest_module.patch: -------------------------------------------------------------------------------- 1 | diff --git a/drivers/misc/irqtest.c b/drivers/misc/irqtest.c 2 | index 1cb8636599d7..e73d35e87303 100644 3 | --- a/drivers/misc/irqtest.c 4 | +++ b/drivers/misc/irqtest.c 5 | @@ -14,6 +14,7 @@ 6 | #include 7 | #include 8 | #include 9 | +#include 10 | 11 | /* 12 | * Module data 13 | @@ -23,12 +24,37 @@ static struct irqtest_data { 14 | int irq; 15 | unsigned int pin; 16 | struct device *dev; 17 | + struct work_struct work; 18 | + struct delayed_work dwork; 19 | } irqinfo; 20 | 21 | +static struct workqueue_struct *irqtest_wq; 22 | + 23 | /* 24 | - * The interrupt handler 25 | + * The interrupt handlers 26 | */ 27 | 28 | +static void irqtest_dwork_handler(struct work_struct *ptr) 29 | +{ 30 | + struct irqtest_data *info = container_of(ptr, struct irqtest_data, 31 | + dwork.work); 32 | + struct device *dev = info->dev; 33 | + 34 | + dev_info(dev, "delayed work executed after work"); 35 | +} 36 | + 37 | +static void irqtest_work_handler(struct work_struct *ptr) 38 | +{ 39 | + struct irqtest_data *info = container_of(ptr, struct irqtest_data, 40 | + work); 41 | + struct device *dev = info->dev; 42 | + 43 | + dev_info(dev, "work executed after IRQ %d", info->irq); 44 | + 45 | + /* Schedule the delayed work after 2 seconds */ 46 | + queue_delayed_work(irqtest_wq, &info->dwork, 2*HZ); 47 | +} 48 | + 49 | static irqreturn_t irqtest_interrupt(int irq, void *dev_id) 50 | { 51 | struct irqtest_data *info = dev_id; 52 | @@ -36,6 +62,8 @@ static irqreturn_t irqtest_interrupt(int irq, void *dev_id) 53 | 54 | dev_info(dev, "interrupt occurred on IRQ %d\n", irq); 55 | 56 | + queue_work(irqtest_wq, &info->work); 57 | + 58 | return IRQ_HANDLED; 59 | } 60 | 61 | @@ -80,24 +108,40 @@ static int irqtest_probe(struct platform_device *pdev) 62 | dev_info(dev, "GPIO %u correspond to IRQ %d\n", 63 | irqinfo.pin, irqinfo.irq); 64 | 65 | + /* Create our work queue and init works */ 66 | + irqtest_wq = create_singlethread_workqueue("irqtest"); 67 | + if (!irqtest_wq) { 68 | + dev_err(dev, "failed to create work queue!\n"); 69 | + return -EINVAL; 70 | + } 71 | + INIT_WORK(&irqinfo.work, irqtest_work_handler); 72 | + INIT_DELAYED_WORK(&irqinfo.dwork, irqtest_dwork_handler); 73 | + 74 | /* Request IRQ line and setup corresponding handler */ 75 | irqinfo.dev = dev; 76 | ret = request_irq(irqinfo.irq, irqtest_interrupt, 0, 77 | "irqtest", &irqinfo); 78 | if (ret) { 79 | dev_err(dev, "cannot register IRQ %d\n", irqinfo.irq); 80 | - return -EIO; 81 | + goto flush_wq; 82 | } 83 | dev_info(dev, "interrupt handler for IRQ %d is now ready!\n", 84 | irqinfo.irq); 85 | 86 | return 0; 87 | + 88 | +flush_wq: 89 | + flush_workqueue(irqtest_wq); 90 | + return -EIO; 91 | } 92 | 93 | static int irqtest_remove(struct platform_device *pdev) 94 | { 95 | struct device *dev = &pdev->dev; 96 | 97 | + cancel_work_sync(&irqinfo.work); 98 | + cancel_delayed_work_sync(&irqinfo.dwork); 99 | + flush_workqueue(irqtest_wq); 100 | free_irq(irqinfo.irq, &irqinfo); 101 | dev_info(dev, "IRQ %d is now unmanaged!\n", irqinfo.irq); 102 | 103 | -------------------------------------------------------------------------------- /Chapter05/atomic/Makefile: -------------------------------------------------------------------------------- 1 | ifndef KERNEL_DIR 2 | $(error KERNEL_DIR must be set in the command line) 3 | endif 4 | PWD := $(shell pwd) 5 | ARCH ?= arm64 6 | CROSS_COMPILE ?= aarch64-linux-gnu- 7 | 8 | # This specifies the kernel module to be compiled 9 | obj-m += mutex.o 10 | obj-m += spinlock.o 11 | obj-m += atomic.o 12 | 13 | # The default action 14 | all: modules 15 | 16 | # The main tasks 17 | modules clean: 18 | make -C $(KERNEL_DIR) \ 19 | ARCH=$(ARCH) \ 20 | CROSS_COMPILE=$(CROSS_COMPILE) \ 21 | SUBDIRS=$(PWD) $@ 22 | -------------------------------------------------------------------------------- /Chapter05/atomic/atomic.c: -------------------------------------------------------------------------------- 1 | /* 2 | * Kernel timer 3 | */ 4 | 5 | #define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__ 6 | #include 7 | #include 8 | #include 9 | #include 10 | 11 | /* 12 | * Module parameter and data 13 | */ 14 | 15 | static int delay_ms = 1000; 16 | module_param(delay_ms, int, S_IRUSR | S_IWUSR); 17 | MODULE_PARM_DESC(delay_ms, "kernel timer delay is ms"); 18 | 19 | static atomic_t bitmap = ATOMIC_INIT(0xff); 20 | 21 | static struct ktimer_data { 22 | struct timer_list timer; 23 | long delay_jiffies; 24 | atomic_t data; 25 | } ainfo; 26 | 27 | /* 28 | * The kernel timer handler 29 | */ 30 | 31 | static void ktimer_handler(struct timer_list *t) 32 | { 33 | struct ktimer_data *info = from_timer(info, t, timer); 34 | 35 | pr_info("kernel timer expired at %ld (data=%d)\n", 36 | jiffies, atomic_dec_if_positive(&info->data)); 37 | 38 | /* Compute an atomic bitmap operation */ 39 | atomic_xor(0xff, &bitmap); 40 | pr_info("bitmap=%0x\n", atomic_read(&bitmap)); 41 | 42 | /* Reschedule kernel timer */ 43 | mod_timer(&info->timer, jiffies + info->delay_jiffies); 44 | } 45 | 46 | /* 47 | * Probe/remove functions 48 | */ 49 | 50 | static int __init ktimer_init(void) 51 | { 52 | /* Save kernel timer delay */ 53 | ainfo.delay_jiffies = msecs_to_jiffies(delay_ms); 54 | pr_info("delay is set to %dms (%ld jiffies)\n", 55 | delay_ms, ainfo.delay_jiffies); 56 | 57 | /* Init the atomic data */ 58 | atomic_set(&ainfo.data, 10); 59 | 60 | /* Setup and start the kernel timer after required delay */ 61 | timer_setup(&ainfo.timer, ktimer_handler, 0); 62 | mod_timer(&ainfo.timer, jiffies + ainfo.delay_jiffies); 63 | 64 | pr_info("kernel timer module loaded\n"); 65 | return 0; 66 | } 67 | 68 | static void __exit ktimer_exit(void) 69 | { 70 | del_timer_sync(&ainfo.timer); 71 | 72 | pr_info("kernel timer module unloaded\n"); 73 | } 74 | 75 | module_init(ktimer_init); 76 | module_exit(ktimer_exit); 77 | 78 | MODULE_AUTHOR("Rodolfo Giometti"); 79 | MODULE_DESCRIPTION("Kernel timer"); 80 | MODULE_LICENSE("GPL"); 81 | -------------------------------------------------------------------------------- /Chapter05/atomic/mutex.c: -------------------------------------------------------------------------------- 1 | /* 2 | * Mutex 3 | */ 4 | 5 | #define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__ 6 | #include 7 | #include 8 | #include 9 | #include 10 | 11 | /* 12 | * Module parameter and data 13 | */ 14 | 15 | static int delay_ms = 1000; 16 | module_param(delay_ms, int, S_IRUSR | S_IWUSR); 17 | MODULE_PARM_DESC(delay_ms, "kernel timer delay is ms"); 18 | 19 | static struct ktimer_data { 20 | struct mutex lock; 21 | struct timer_list timer; 22 | long delay_jiffies; 23 | int data; 24 | } minfo; 25 | 26 | /* 27 | * The kernel timer handler 28 | */ 29 | 30 | static void ktimer_handler(struct timer_list *t) 31 | { 32 | struct ktimer_data *info = from_timer(info, t, timer); 33 | int ret; 34 | 35 | pr_info("kernel timer expired at %ld (data=%d)\n", 36 | jiffies, info->data); 37 | ret = mutex_trylock(&info->lock); 38 | if (ret) { 39 | info->data++; 40 | mutex_unlock(&info->lock); 41 | } else 42 | pr_err("cannot get the lock!\n"); 43 | 44 | /* Reschedule kernel timer */ 45 | mod_timer(&info->timer, jiffies + info->delay_jiffies); 46 | } 47 | 48 | /* 49 | * Probe/remove functions 50 | */ 51 | 52 | static int __init ktimer_init(void) 53 | { 54 | /* Save kernel timer delay */ 55 | minfo.delay_jiffies = msecs_to_jiffies(delay_ms); 56 | pr_info("delay is set to %dms (%ld jiffies)\n", 57 | delay_ms, minfo.delay_jiffies); 58 | 59 | /* Init the mutex */ 60 | mutex_init(&minfo.lock); 61 | 62 | /* Setup and start the kernel timer */ 63 | timer_setup(&minfo.timer, ktimer_handler, 0); 64 | mod_timer(&minfo.timer, jiffies); 65 | 66 | mutex_lock(&minfo.lock); 67 | minfo.data++; 68 | mutex_unlock(&minfo.lock); 69 | 70 | pr_info("mutex module loaded\n"); 71 | return 0; 72 | } 73 | 74 | static void __exit ktimer_exit(void) 75 | { 76 | del_timer_sync(&minfo.timer); 77 | 78 | pr_info("mutex module unloaded\n"); 79 | } 80 | 81 | module_init(ktimer_init); 82 | module_exit(ktimer_exit); 83 | 84 | MODULE_AUTHOR("Rodolfo Giometti"); 85 | MODULE_DESCRIPTION("Mutex"); 86 | MODULE_LICENSE("GPL"); 87 | -------------------------------------------------------------------------------- /Chapter05/atomic/spinlock.c: -------------------------------------------------------------------------------- 1 | /* 2 | * Mutex 3 | */ 4 | 5 | #define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__ 6 | #include 7 | #include 8 | #include 9 | #include 10 | 11 | /* 12 | * Module parameter and data 13 | */ 14 | 15 | static int delay_ms = 1000; 16 | module_param(delay_ms, int, S_IRUSR | S_IWUSR); 17 | MODULE_PARM_DESC(delay_ms, "kernel timer delay is ms"); 18 | 19 | static struct ktimer_data { 20 | struct spinlock lock; 21 | struct timer_list timer; 22 | long delay_jiffies; 23 | int data; 24 | } sinfo; 25 | 26 | /* 27 | * The kernel timer handler 28 | */ 29 | 30 | static void ktimer_handler(struct timer_list *t) 31 | { 32 | struct ktimer_data *info = from_timer(info, t, timer); 33 | 34 | pr_info("kernel timer expired at %ld (data=%d)\n", 35 | jiffies, info->data); 36 | spin_lock(&sinfo.lock); 37 | info->data++; 38 | spin_unlock(&info->lock); 39 | 40 | /* Reschedule kernel timer */ 41 | mod_timer(&info->timer, jiffies + info->delay_jiffies); 42 | } 43 | 44 | /* 45 | * Probe/remove functions 46 | */ 47 | 48 | static int __init ktimer_init(void) 49 | { 50 | /* Save kernel timer delay */ 51 | sinfo.delay_jiffies = msecs_to_jiffies(delay_ms); 52 | pr_info("delay is set to %dms (%ld jiffies)\n", 53 | delay_ms, sinfo.delay_jiffies); 54 | 55 | /* Init the spinlock */ 56 | spin_lock_init(&sinfo.lock); 57 | 58 | /* Setup and start the kernel timer */ 59 | timer_setup(&sinfo.timer, ktimer_handler, 0); 60 | mod_timer(&sinfo.timer, jiffies); 61 | 62 | spin_lock(&sinfo.lock); 63 | sinfo.data++; 64 | spin_unlock(&sinfo.lock); 65 | 66 | pr_info("spinlock module loaded\n"); 67 | return 0; 68 | } 69 | 70 | static void __exit ktimer_exit(void) 71 | { 72 | del_timer_sync(&sinfo.timer); 73 | 74 | pr_info("spinlock module unloaded\n"); 75 | } 76 | 77 | module_init(ktimer_init); 78 | module_exit(ktimer_exit); 79 | 80 | MODULE_AUTHOR("Rodolfo Giometti"); 81 | MODULE_DESCRIPTION("Mutex"); 82 | MODULE_LICENSE("GPL"); 83 | -------------------------------------------------------------------------------- /Chapter05/notifier/Makefile: -------------------------------------------------------------------------------- 1 | ifndef KERNEL_DIR 2 | $(error KERNEL_DIR must be set in the command line) 3 | endif 4 | PWD := $(shell pwd) 5 | ARCH ?= arm64 6 | CROSS_COMPILE ?= aarch64-linux-gnu- 7 | 8 | # This specifies the kernel module to be compiled 9 | obj-m += notifier.o 10 | 11 | # The default action 12 | all: modules 13 | 14 | # The main tasks 15 | modules clean: 16 | make -C $(KERNEL_DIR) \ 17 | ARCH=$(ARCH) \ 18 | CROSS_COMPILE=$(CROSS_COMPILE) \ 19 | SUBDIRS=$(PWD) $@ 20 | -------------------------------------------------------------------------------- /Chapter05/notifier/hires_timer.c: -------------------------------------------------------------------------------- 1 | /* 2 | * High resolution timer 3 | */ 4 | 5 | #define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__ 6 | #include 7 | #include 8 | #include 9 | 10 | /* 11 | * Module parameter and data 12 | */ 13 | 14 | static int delay_ns = 1000000000; 15 | module_param(delay_ns, int, S_IRUSR | S_IWUSR); 16 | MODULE_PARM_DESC(delay_ns, "kernel timer delay is ns"); 17 | 18 | static struct hires_timer_data { 19 | struct hrtimer timer; 20 | unsigned int data; 21 | } hires_tinfo; 22 | 23 | /* 24 | * The kernel timer handler 25 | */ 26 | 27 | static enum hrtimer_restart hires_timer_handler(struct hrtimer *ptr) 28 | { 29 | struct hires_timer_data *info = container_of(ptr, 30 | struct hires_timer_data, timer); 31 | 32 | pr_info("kernel timer expired at %ld (data=%d)\n", 33 | jiffies, info->data++); 34 | 35 | return HRTIMER_RESTART; 36 | } 37 | 38 | /* 39 | * Probe/remove functions 40 | */ 41 | 42 | static int __init hires_timer_init(void) 43 | { 44 | /* Set up hires timer delay */ 45 | 46 | pr_info("delay is set to %dns\n", delay_ns); 47 | 48 | /* Setup and start the hires timer */ 49 | hires_tinfo.timer.function = hires_timer_handler; 50 | hrtimer_start(&hires_tinfo.timer, ns_to_ktime(delay_ns), 51 | HRTIMER_MODE_REL | HRTIMER_MODE_SOFT); 52 | 53 | pr_info("hires timer module loaded\n"); 54 | return 0; 55 | } 56 | 57 | static void __exit hires_timer_exit(void) 58 | { 59 | hrtimer_cancel(&hires_tinfo.timer); 60 | 61 | pr_info("hires timer module unloaded\n"); 62 | } 63 | 64 | module_init(hires_timer_init); 65 | module_exit(hires_timer_exit); 66 | 67 | MODULE_AUTHOR("Rodolfo Giometti"); 68 | MODULE_DESCRIPTION("High resolution timer"); 69 | MODULE_LICENSE("GPL"); 70 | -------------------------------------------------------------------------------- /Chapter05/notifier/notifier.c: -------------------------------------------------------------------------------- 1 | /* 2 | * Kernel timer 3 | */ 4 | 5 | #define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__ 6 | #include 7 | #include 8 | #include 9 | #include 10 | 11 | /* 12 | * Module data 13 | */ 14 | 15 | static struct notifier_data { 16 | struct notifier_block netdevice_nb; 17 | struct notifier_block reboot_nb; 18 | unsigned int data; 19 | } ninfo; 20 | 21 | 22 | /* 23 | * The notifier handlers 24 | */ 25 | 26 | static int netdevice_notifier(struct notifier_block *nb, 27 | unsigned long code, void *unused) 28 | { 29 | struct notifier_data *ninfo = container_of(nb, struct notifier_data, 30 | netdevice_nb); 31 | 32 | pr_info("netdevice: event #%d with code 0x%lx caught!\n", 33 | ninfo->data++, code); 34 | 35 | return NOTIFY_DONE; 36 | } 37 | 38 | static int reboot_notifier(struct notifier_block *nb, 39 | unsigned long code, void *unused) 40 | { 41 | struct notifier_data *ninfo = container_of(nb, struct notifier_data, 42 | reboot_nb); 43 | 44 | pr_info("reboot: event #%d with code 0x%lx caught!\n", 45 | ninfo->data++, code); 46 | 47 | return NOTIFY_DONE; 48 | } 49 | 50 | /* 51 | * Probe/remove functions 52 | */ 53 | 54 | static int __init notifier_init(void) 55 | { 56 | int ret; 57 | 58 | ninfo.netdevice_nb.notifier_call = netdevice_notifier; 59 | ninfo.netdevice_nb.priority = 10; 60 | 61 | ret = register_netdevice_notifier(&ninfo.netdevice_nb); 62 | if (ret) { 63 | pr_err("unable to register netdevice notifier\n"); 64 | return ret; 65 | } 66 | 67 | ninfo.reboot_nb.notifier_call = reboot_notifier; 68 | ninfo.reboot_nb.priority = 10; 69 | 70 | ret = register_reboot_notifier(&ninfo.reboot_nb); 71 | if (ret) { 72 | pr_err("unable to register reboot notifier\n"); 73 | goto unregister_netdevice; 74 | } 75 | 76 | pr_info("notifier module loaded\n"); 77 | 78 | return 0; 79 | 80 | unregister_netdevice: 81 | unregister_netdevice_notifier(&ninfo.netdevice_nb); 82 | return ret; 83 | } 84 | 85 | static void __exit notifier_exit(void) 86 | { 87 | unregister_netdevice_notifier(&ninfo.netdevice_nb); 88 | unregister_reboot_notifier(&ninfo.reboot_nb); 89 | 90 | pr_info("notifier module unloaded\n"); 91 | } 92 | 93 | module_init(notifier_init); 94 | module_exit(notifier_exit); 95 | 96 | MODULE_AUTHOR("Rodolfo Giometti"); 97 | MODULE_DESCRIPTION("Kernel timer"); 98 | MODULE_LICENSE("GPL"); 99 | -------------------------------------------------------------------------------- /Chapter05/timer/Makefile: -------------------------------------------------------------------------------- 1 | ifndef KERNEL_DIR 2 | $(error KERNEL_DIR must be set in the command line) 3 | endif 4 | PWD := $(shell pwd) 5 | ARCH ?= arm64 6 | CROSS_COMPILE ?= aarch64-linux-gnu- 7 | 8 | # This specifies the kernel module to be compiled 9 | obj-m += hires_timer.o 10 | obj-m += ktimer.o 11 | 12 | # The default action 13 | all: modules 14 | 15 | # The main tasks 16 | modules clean: 17 | make -C $(KERNEL_DIR) \ 18 | ARCH=$(ARCH) \ 19 | CROSS_COMPILE=$(CROSS_COMPILE) \ 20 | SUBDIRS=$(PWD) $@ 21 | -------------------------------------------------------------------------------- /Chapter05/timer/hires_timer.c: -------------------------------------------------------------------------------- 1 | /* 2 | * High resolution timer 3 | */ 4 | 5 | #define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__ 6 | #include 7 | #include 8 | #include 9 | 10 | /* 11 | * Module parameter and data 12 | */ 13 | 14 | static int delay_ns = 1000000000; 15 | module_param(delay_ns, int, S_IRUSR | S_IWUSR); 16 | MODULE_PARM_DESC(delay_ns, "kernel timer delay is ns"); 17 | 18 | static struct hires_timer_data { 19 | struct hrtimer timer; 20 | unsigned int data; 21 | } hires_tinfo; 22 | 23 | /* 24 | * The kernel timer handler 25 | */ 26 | 27 | static enum hrtimer_restart hires_timer_handler(struct hrtimer *ptr) 28 | { 29 | struct hires_timer_data *info = container_of(ptr, 30 | struct hires_timer_data, timer); 31 | 32 | pr_info("kernel timer expired at %ld (data=%d)\n", 33 | jiffies, info->data++); 34 | 35 | /* Now forward the expiration time and ask to be rescheduled */ 36 | hrtimer_forward_now(&info->timer, ns_to_ktime(delay_ns)); 37 | return HRTIMER_RESTART; 38 | } 39 | 40 | /* 41 | * Probe/remove functions 42 | */ 43 | 44 | static int __init hires_timer_init(void) 45 | { 46 | /* Set up hires timer delay */ 47 | 48 | pr_info("delay is set to %dns\n", delay_ns); 49 | 50 | /* Setup and start the hires timer */ 51 | hrtimer_init(&hires_tinfo.timer, CLOCK_MONOTONIC, 52 | HRTIMER_MODE_REL | HRTIMER_MODE_SOFT); 53 | hires_tinfo.timer.function = hires_timer_handler; 54 | hrtimer_start(&hires_tinfo.timer, ns_to_ktime(delay_ns), 55 | HRTIMER_MODE_REL | HRTIMER_MODE_SOFT); 56 | 57 | pr_info("hires timer module loaded\n"); 58 | return 0; 59 | } 60 | 61 | static void __exit hires_timer_exit(void) 62 | { 63 | hrtimer_cancel(&hires_tinfo.timer); 64 | 65 | pr_info("hires timer module unloaded\n"); 66 | } 67 | 68 | module_init(hires_timer_init); 69 | module_exit(hires_timer_exit); 70 | 71 | MODULE_AUTHOR("Rodolfo Giometti"); 72 | MODULE_DESCRIPTION("High resolution timer"); 73 | MODULE_LICENSE("GPL"); 74 | -------------------------------------------------------------------------------- /Chapter05/timer/ktimer.c: -------------------------------------------------------------------------------- 1 | /* 2 | * Kernel timer 3 | */ 4 | 5 | #define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__ 6 | #include 7 | #include 8 | #include 9 | 10 | /* 11 | * Module parameter and data 12 | */ 13 | 14 | static int delay_ms = 1000; 15 | module_param(delay_ms, int, S_IRUSR | S_IWUSR); 16 | MODULE_PARM_DESC(delay_ms, "kernel timer delay is ms"); 17 | 18 | static struct ktimer_data { 19 | struct timer_list timer; 20 | long delay_jiffies; 21 | unsigned int data; 22 | } ktinfo; 23 | 24 | /* 25 | * The kernel timer handler 26 | */ 27 | 28 | static void ktimer_handler(struct timer_list *t) 29 | { 30 | struct ktimer_data *info = from_timer(info, t, timer); 31 | 32 | pr_info("kernel timer expired at %ld (data=%d)\n", 33 | jiffies, info->data++); 34 | 35 | /* Reschedule kernel timer */ 36 | mod_timer(&info->timer, jiffies + info->delay_jiffies); 37 | } 38 | 39 | /* 40 | * Probe/remove functions 41 | */ 42 | 43 | static int __init ktimer_init(void) 44 | { 45 | /* Save kernel timer delay */ 46 | ktinfo.delay_jiffies = msecs_to_jiffies(delay_ms); 47 | pr_info("delay is set to %dms (%ld jiffies)\n", 48 | delay_ms, ktinfo.delay_jiffies); 49 | 50 | /* Setup and start the kernel timer */ 51 | timer_setup(&ktinfo.timer, ktimer_handler, 0); 52 | mod_timer(&ktinfo.timer, jiffies + ktinfo.delay_jiffies); 53 | 54 | pr_info("kernel timer module loaded\n"); 55 | return 0; 56 | } 57 | 58 | static void __exit ktimer_exit(void) 59 | { 60 | del_timer_sync(&ktinfo.timer); 61 | 62 | pr_info("kernel timer module unloaded\n"); 63 | } 64 | 65 | module_init(ktimer_init); 66 | module_exit(ktimer_exit); 67 | 68 | MODULE_AUTHOR("Rodolfo Giometti"); 69 | MODULE_DESCRIPTION("Kernel timer"); 70 | MODULE_LICENSE("GPL"); 71 | -------------------------------------------------------------------------------- /Chapter05/wait_event/Makefile: -------------------------------------------------------------------------------- 1 | ifndef KERNEL_DIR 2 | $(error KERNEL_DIR must be set in the command line) 3 | endif 4 | PWD := $(shell pwd) 5 | ARCH ?= arm64 6 | CROSS_COMPILE ?= aarch64-linux-gnu- 7 | 8 | # This specifies the kernel module to be compiled 9 | obj-m += waitqueue.o 10 | obj-m += completion.o 11 | 12 | # The default action 13 | all: modules 14 | 15 | # The main tasks 16 | modules clean: 17 | make -C $(KERNEL_DIR) \ 18 | ARCH=$(ARCH) \ 19 | CROSS_COMPILE=$(CROSS_COMPILE) \ 20 | SUBDIRS=$(PWD) $@ 21 | -------------------------------------------------------------------------------- /Chapter05/wait_event/completion.c: -------------------------------------------------------------------------------- 1 | /* 2 | * Completion 3 | */ 4 | 5 | #define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__ 6 | #include 7 | #include 8 | #include 9 | #include 10 | 11 | /* 12 | * Module parameter and data 13 | */ 14 | 15 | static int delay_ms = 5000; 16 | module_param(delay_ms, int, S_IRUSR | S_IWUSR); 17 | MODULE_PARM_DESC(delay_ms, "kernel timer delay is ms"); 18 | 19 | static struct ktimer_data { 20 | struct completion done; 21 | struct timer_list timer; 22 | long delay_jiffies; 23 | unsigned int data; 24 | } cinfo; 25 | 26 | /* 27 | * The kernel timer handler 28 | */ 29 | 30 | static void ktimer_handler(struct timer_list *t) 31 | { 32 | struct ktimer_data *info = from_timer(info, t, timer); 33 | 34 | pr_info("kernel timer expired at %ld (data=%d)\n", 35 | jiffies, info->data++); 36 | 37 | /* Signal that job is done */ 38 | complete(&info->done); 39 | } 40 | 41 | /* 42 | * Probe/remove functions 43 | */ 44 | 45 | static int __init completion_init(void) 46 | { 47 | /* Save kernel timer delay */ 48 | cinfo.delay_jiffies = msecs_to_jiffies(delay_ms); 49 | pr_info("delay is set to %dms (%ld jiffies)\n", 50 | delay_ms, cinfo.delay_jiffies); 51 | 52 | /* Init the wait queue */ 53 | init_completion(&cinfo.done); 54 | 55 | /* Setup and start the kernel timer */ 56 | timer_setup(&cinfo.timer, ktimer_handler, 0); 57 | mod_timer(&cinfo.timer, jiffies + cinfo.delay_jiffies); 58 | 59 | /* Wait for completition... */ 60 | wait_for_completion(&cinfo.done); 61 | 62 | pr_info("job done\n"); 63 | 64 | return 0; 65 | } 66 | 67 | static void __exit completion_exit(void) 68 | { 69 | del_timer_sync(&cinfo.timer); 70 | 71 | pr_info("module unloaded\n"); 72 | } 73 | 74 | module_init(completion_init); 75 | module_exit(completion_exit); 76 | 77 | MODULE_AUTHOR("Rodolfo Giometti"); 78 | MODULE_DESCRIPTION("Completion"); 79 | MODULE_LICENSE("GPL"); 80 | -------------------------------------------------------------------------------- /Chapter05/wait_event/waitqueue.c: -------------------------------------------------------------------------------- 1 | /* 2 | * Wait Queue 3 | */ 4 | 5 | #define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__ 6 | #include 7 | #include 8 | #include 9 | #include 10 | 11 | /* 12 | * Module parameter and data 13 | */ 14 | 15 | static int delay_ms = 1000; 16 | module_param(delay_ms, int, S_IRUSR | S_IWUSR); 17 | MODULE_PARM_DESC(delay_ms, "kernel timer delay is ms"); 18 | 19 | static struct ktimer_data { 20 | struct wait_queue_head waitq; 21 | struct timer_list timer; 22 | long delay_jiffies; 23 | unsigned int data; 24 | } wqinfo; 25 | 26 | /* 27 | * The kernel timer handler 28 | */ 29 | 30 | static void ktimer_handler(struct timer_list *t) 31 | { 32 | struct ktimer_data *info = from_timer(info, t, timer); 33 | 34 | pr_info("kernel timer expired at %ld (data=%d)\n", 35 | jiffies, info->data++); 36 | 37 | /* Wake up all sleeping processes */ 38 | wake_up_interruptible(&info->waitq); 39 | 40 | /* Reschedule kernel timer */ 41 | mod_timer(&info->timer, jiffies + info->delay_jiffies); 42 | } 43 | 44 | /* 45 | * Probe/remove functions 46 | */ 47 | 48 | static int __init waitqueue_init(void) 49 | { 50 | int ret; 51 | 52 | /* Save kernel timer delay */ 53 | wqinfo.delay_jiffies = msecs_to_jiffies(delay_ms); 54 | pr_info("delay is set to %dms (%ld jiffies)\n", 55 | delay_ms, wqinfo.delay_jiffies); 56 | 57 | /* Init the wait queue */ 58 | init_waitqueue_head(&wqinfo.waitq); 59 | 60 | /* Setup and start the kernel timer */ 61 | timer_setup(&wqinfo.timer, ktimer_handler, 0); 62 | mod_timer(&wqinfo.timer, jiffies + wqinfo.delay_jiffies); 63 | 64 | /* Wait for the wake up event... */ 65 | ret = wait_event_interruptible(wqinfo.waitq, wqinfo.data > 5); 66 | if (ret < 0) 67 | goto exit; 68 | 69 | pr_info("got event data > 5\n"); 70 | 71 | return 0; 72 | 73 | exit: 74 | if (ret == -ERESTARTSYS) 75 | pr_info("interrupted by signal!\n"); 76 | else 77 | pr_err("unable to wait for event\n"); 78 | 79 | del_timer_sync(&wqinfo.timer); 80 | 81 | return ret; 82 | } 83 | 84 | static void __exit waitqueue_exit(void) 85 | { 86 | del_timer_sync(&wqinfo.timer); 87 | 88 | pr_info("module unloaded\n"); 89 | } 90 | 91 | module_init(waitqueue_init); 92 | module_exit(waitqueue_exit); 93 | 94 | MODULE_AUTHOR("Rodolfo Giometti"); 95 | MODULE_DESCRIPTION("Wait queue"); 96 | MODULE_LICENSE("GPL"); 97 | -------------------------------------------------------------------------------- /Chapter06/data_types/Makefile: -------------------------------------------------------------------------------- 1 | ifndef KERNEL_DIR 2 | $(error KERNEL_DIR must be set in the command line) 3 | endif 4 | PWD := $(shell pwd) 5 | ARCH ?= arm64 6 | CROSS_COMPILE ?= aarch64-linux-gnu- 7 | 8 | # This specifies the kernel module to be compiled 9 | obj-m += data_types.o 10 | 11 | # The default action 12 | all: modules 13 | 14 | # The main tasks 15 | modules clean: 16 | make -C $(KERNEL_DIR) \ 17 | ARCH=$(ARCH) \ 18 | CROSS_COMPILE=$(CROSS_COMPILE) \ 19 | SUBDIRS=$(PWD) $@ 20 | -------------------------------------------------------------------------------- /Chapter06/data_types/data_types.c: -------------------------------------------------------------------------------- 1 | /* 2 | * Kernel data types 3 | */ 4 | 5 | #define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__ 6 | #include 7 | #include 8 | #include 9 | 10 | static long base_addr = 0x80000000; 11 | module_param(base_addr, long, S_IRUSR | S_IWUSR); 12 | MODULE_PARM_DESC(base_addr, "base address"); 13 | 14 | /* 15 | * Peripheral mapping 16 | */ 17 | 18 | struct dtypes_s { 19 | u32 reg0; 20 | u8 pad0[2]; 21 | u16 reg1; 22 | u32 pad1[2]; 23 | u8 reg2; 24 | u8 reg3; 25 | u16 reg4; 26 | u32 reg5; 27 | } __attribute__ ((packed)); 28 | 29 | /* 30 | * Init & exit stuff 31 | */ 32 | 33 | static int __init data_types_init(void) 34 | { 35 | struct dtypes_s *ptr = (struct dtypes_s *) base_addr; 36 | 37 | pr_info("\tu8\tu16\tu32\tu64\n"); 38 | pr_info("size\t%ld\t%ld\t%ld\t%ld\n", 39 | sizeof(u8), sizeof(u16), sizeof(u32), sizeof(u64)); 40 | 41 | pr_info("name\tptr\n"); 42 | pr_info("reg0\t%px\n", &ptr->reg0); 43 | pr_info("reg1\t%px\n", &ptr->reg1); 44 | pr_info("reg2\t%px\n", &ptr->reg2); 45 | pr_info("reg3\t%px\n", &ptr->reg3); 46 | pr_info("reg4\t%px\n", &ptr->reg4); 47 | pr_info("reg5\t%px\n", &ptr->reg5); 48 | 49 | return -EINVAL; 50 | } 51 | 52 | static void __exit data_types_exit(void) 53 | { 54 | pr_info("unloaded\n"); 55 | } 56 | 57 | module_init(data_types_init); 58 | module_exit(data_types_exit); 59 | 60 | MODULE_LICENSE("GPL"); 61 | MODULE_AUTHOR("Rodolfo Giometti"); 62 | MODULE_DESCRIPTION("Kernel data types"); 63 | MODULE_VERSION("0.1"); 64 | -------------------------------------------------------------------------------- /Chapter06/hashtable/Makefile: -------------------------------------------------------------------------------- 1 | ifndef KERNEL_DIR 2 | $(error KERNEL_DIR must be set in the command line) 3 | endif 4 | PWD := $(shell pwd) 5 | ARCH ?= arm64 6 | CROSS_COMPILE ?= aarch64-linux-gnu- 7 | 8 | # This specifies the kernel module to be compiled 9 | obj-m += hashtable.o 10 | 11 | # The default action 12 | all: modules 13 | 14 | # The main tasks 15 | modules clean: 16 | make -C $(KERNEL_DIR) \ 17 | ARCH=$(ARCH) \ 18 | CROSS_COMPILE=$(CROSS_COMPILE) \ 19 | SUBDIRS=$(PWD) $@ 20 | -------------------------------------------------------------------------------- /Chapter06/hashtable/hashtable.c: -------------------------------------------------------------------------------- 1 | /* 2 | * Kernel hash tables 3 | */ 4 | 5 | #define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__ 6 | #include 7 | #include 8 | 9 | static DEFINE_HASHTABLE(data_hash, 1); 10 | 11 | struct h_struct { 12 | int data; 13 | struct hlist_node node; 14 | }; 15 | 16 | static int hash_func(int data) 17 | { 18 | return data % 2; 19 | } 20 | 21 | /* 22 | * Local functions 23 | */ 24 | 25 | static void add_node(struct h_struct *new) 26 | { 27 | int key = hash_func(new->data); 28 | 29 | hash_add(data_hash, &new->node, key); 30 | } 31 | 32 | static void del_node(int data) 33 | { 34 | int key = hash_func(data); 35 | struct h_struct *entry; 36 | 37 | hash_for_each_possible(data_hash, entry, node, key) { 38 | if (entry->data == data) { 39 | hash_del(&entry->node); 40 | return; 41 | } 42 | } 43 | } 44 | 45 | static void print_nodes(void) 46 | { 47 | int key; 48 | struct h_struct *entry; 49 | 50 | hash_for_each(data_hash, key, entry, node) 51 | pr_info("data=%d\n", entry->data); 52 | } 53 | 54 | /* 55 | * Init & exit stuff 56 | */ 57 | 58 | static int __init hashtable_init(void) 59 | { 60 | struct h_struct e1 = { 61 | .data = 5 62 | }; 63 | struct h_struct e2 = { 64 | .data = 2 65 | }; 66 | struct h_struct e3 = { 67 | .data = 7 68 | }; 69 | 70 | pr_info("add e1...\n"); 71 | add_node(&e1); 72 | print_nodes(); 73 | 74 | pr_info("add e2, e3...\n"); 75 | add_node(&e2); 76 | add_node(&e3); 77 | print_nodes(); 78 | 79 | pr_info("del data=5\n"); 80 | del_node(5); 81 | print_nodes(); 82 | 83 | return -EINVAL; 84 | } 85 | 86 | static void __exit hashtable_exit(void) 87 | { 88 | pr_info("unloaded\n"); 89 | } 90 | 91 | module_init(hashtable_init); 92 | module_exit(hashtable_exit); 93 | 94 | MODULE_LICENSE("GPL"); 95 | MODULE_AUTHOR("Rodolfo Giometti"); 96 | MODULE_DESCRIPTION("Kernel hash tables"); 97 | MODULE_VERSION("0.1"); 98 | -------------------------------------------------------------------------------- /Chapter06/helper_funcs/Makefile: -------------------------------------------------------------------------------- 1 | ifndef KERNEL_DIR 2 | $(error KERNEL_DIR must be set in the command line) 3 | endif 4 | PWD := $(shell pwd) 5 | ARCH ?= arm64 6 | CROSS_COMPILE ?= aarch64-linux-gnu- 7 | 8 | # This specifies the kernel module to be compiled 9 | obj-m += helper_funcs.o 10 | 11 | # The default action 12 | all: modules 13 | 14 | # The main tasks 15 | modules clean: 16 | make -C $(KERNEL_DIR) \ 17 | ARCH=$(ARCH) \ 18 | CROSS_COMPILE=$(CROSS_COMPILE) \ 19 | SUBDIRS=$(PWD) $@ 20 | -------------------------------------------------------------------------------- /Chapter06/helper_funcs/helper_funcs.c: -------------------------------------------------------------------------------- 1 | /* 2 | * Kernel helper functions 3 | */ 4 | 5 | #define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__ 6 | #include 7 | #include 8 | #include 9 | 10 | static char *str = "default string"; 11 | module_param(str, charp, S_IRUSR | S_IWUSR); 12 | MODULE_PARM_DESC(str, "a string value"); 13 | 14 | #define STR2_LEN 32 15 | 16 | /* 17 | * Init & exit stuff 18 | */ 19 | 20 | static int __init helper_funcs_init(void) 21 | { 22 | char str2[STR2_LEN]; 23 | 24 | pr_info("str=\"%s\"\n", str); 25 | pr_info("str size=%ld\n", strlen(str)); 26 | 27 | strncpy(str2, str, STR2_LEN); 28 | 29 | pr_info("str2=\"%s\"\n", str2); 30 | pr_info("str2 size=%ld\n", strlen(str2)); 31 | 32 | return -EINVAL; 33 | } 34 | 35 | static void __exit helper_funcs_exit(void) 36 | { 37 | pr_info("unloaded\n"); 38 | } 39 | 40 | module_init(helper_funcs_init); 41 | module_exit(helper_funcs_exit); 42 | 43 | MODULE_LICENSE("GPL"); 44 | MODULE_AUTHOR("Rodolfo Giometti"); 45 | MODULE_DESCRIPTION("Kernel helper functions"); 46 | MODULE_VERSION("0.1"); 47 | -------------------------------------------------------------------------------- /Chapter06/list/Makefile: -------------------------------------------------------------------------------- 1 | ifndef KERNEL_DIR 2 | $(error KERNEL_DIR must be set in the command line) 3 | endif 4 | PWD := $(shell pwd) 5 | ARCH ?= arm64 6 | CROSS_COMPILE ?= aarch64-linux-gnu- 7 | 8 | # This specifies the kernel module to be compiled 9 | obj-m += list.o 10 | 11 | # The default action 12 | all: modules 13 | 14 | # The main tasks 15 | modules clean: 16 | make -C $(KERNEL_DIR) \ 17 | ARCH=$(ARCH) \ 18 | CROSS_COMPILE=$(CROSS_COMPILE) \ 19 | SUBDIRS=$(PWD) $@ 20 | -------------------------------------------------------------------------------- /Chapter06/list/list.c: -------------------------------------------------------------------------------- 1 | /* 2 | * Kernel lists 3 | */ 4 | 5 | #define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__ 6 | #include 7 | #include 8 | 9 | static LIST_HEAD(data_list); 10 | 11 | struct l_struct { 12 | int data; 13 | struct list_head list; 14 | }; 15 | 16 | /* 17 | * Local functions 18 | */ 19 | 20 | static void add_ordered_entry(struct l_struct *new) 21 | { 22 | struct list_head *ptr; 23 | struct l_struct *entry; 24 | 25 | list_for_each(ptr, &data_list) { 26 | entry = list_entry(ptr, struct l_struct, list); 27 | if (entry->data < new->data) { 28 | list_add_tail(&new->list, ptr); 29 | return; 30 | } 31 | } 32 | list_add_tail(&new->list, &data_list); 33 | } 34 | 35 | static void del_entry(int data) 36 | { 37 | struct list_head *ptr; 38 | struct l_struct *entry; 39 | 40 | list_for_each(ptr, &data_list) { 41 | entry = list_entry(ptr, struct l_struct, list); 42 | if (entry->data == data) { 43 | list_del(ptr); 44 | return; 45 | } 46 | } 47 | } 48 | 49 | static void print_entries(void) 50 | { 51 | struct l_struct *entry; 52 | 53 | list_for_each_entry(entry, &data_list, list) 54 | pr_info("data=%d\n", entry->data); 55 | } 56 | 57 | /* 58 | * Init & exit stuff 59 | */ 60 | 61 | static int __init list_init(void) 62 | { 63 | struct l_struct e1 = { 64 | .data = 5 65 | }; 66 | struct l_struct e2 = { 67 | .data = 1 68 | }; 69 | struct l_struct e3 = { 70 | .data = 7 71 | }; 72 | 73 | pr_info("add e1...\n"); 74 | add_ordered_entry(&e1); 75 | print_entries(); 76 | 77 | pr_info("add e2, e3...\n"); 78 | add_ordered_entry(&e2); 79 | add_ordered_entry(&e3); 80 | print_entries(); 81 | 82 | pr_info("del data=5...\n"); 83 | del_entry(5); 84 | print_entries(); 85 | 86 | return -EINVAL; 87 | } 88 | 89 | static void __exit list_exit(void) 90 | { 91 | pr_info("unloaded\n"); 92 | } 93 | 94 | module_init(list_init); 95 | module_exit(list_exit); 96 | 97 | MODULE_LICENSE("GPL"); 98 | MODULE_AUTHOR("Rodolfo Giometti"); 99 | MODULE_DESCRIPTION("Kernel lists"); 100 | MODULE_VERSION("0.1"); 101 | -------------------------------------------------------------------------------- /Chapter06/mem_alloc/Makefile: -------------------------------------------------------------------------------- 1 | ifndef KERNEL_DIR 2 | $(error KERNEL_DIR must be set in the command line) 3 | endif 4 | PWD := $(shell pwd) 5 | ARCH ?= arm64 6 | CROSS_COMPILE ?= aarch64-linux-gnu- 7 | 8 | # This specifies the kernel module to be compiled 9 | obj-m += mem_alloc.o 10 | 11 | # The default action 12 | all: modules 13 | 14 | # The main tasks 15 | modules clean: 16 | make -C $(KERNEL_DIR) \ 17 | ARCH=$(ARCH) \ 18 | CROSS_COMPILE=$(CROSS_COMPILE) \ 19 | SUBDIRS=$(PWD) $@ 20 | -------------------------------------------------------------------------------- /Chapter06/mem_alloc/mem_alloc.c: -------------------------------------------------------------------------------- 1 | /* 2 | * Kernel memory allocation 3 | */ 4 | 5 | #define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__ 6 | #include 7 | #include 8 | #include 9 | #include 10 | #include 11 | 12 | static long size = 4; 13 | module_param(size, long, S_IRUSR | S_IWUSR); 14 | MODULE_PARM_DESC(size, "memory size in Kbytes"); 15 | 16 | /* 17 | * Init & exit stuff 18 | */ 19 | 20 | static int __init mem_alloc_init(void) 21 | { 22 | void *ptr; 23 | 24 | pr_info("size=%ldkbytes\n", size); 25 | 26 | ptr = kmalloc(size << 10, GFP_KERNEL); 27 | pr_info("kmalloc(..., GFP_KERNEL) =%px\n", ptr); 28 | kfree(ptr); 29 | 30 | ptr = kmalloc(size << 10, GFP_ATOMIC); 31 | pr_info("kmalloc(..., GFP_ATOMIC) =%px\n", ptr); 32 | kfree(ptr); 33 | 34 | ptr = vmalloc(size << 10); 35 | pr_info("vmalloc(...) =%px\n", ptr); 36 | vfree(ptr); 37 | 38 | ptr = kvmalloc(size << 10, GFP_KERNEL); 39 | pr_info("kvmalloc(..., GFP_KERNEL)=%px\n", ptr); 40 | kvfree(ptr); 41 | 42 | ptr = kvmalloc(size << 10, GFP_ATOMIC); 43 | pr_info("kvmalloc(..., GFP_ATOMIC)=%px\n", ptr); 44 | kvfree(ptr); 45 | 46 | return -EINVAL; 47 | } 48 | 49 | static void __exit mem_alloc_exit(void) 50 | { 51 | pr_info("unloaded\n"); 52 | } 53 | 54 | module_init(mem_alloc_init); 55 | module_exit(mem_alloc_exit); 56 | 57 | MODULE_LICENSE("GPL"); 58 | MODULE_AUTHOR("Rodolfo Giometti"); 59 | MODULE_DESCRIPTION("Kernel memory allocation"); 60 | MODULE_VERSION("0.1"); 61 | -------------------------------------------------------------------------------- /Chapter06/time/Makefile: -------------------------------------------------------------------------------- 1 | ifndef KERNEL_DIR 2 | $(error KERNEL_DIR must be set in the command line) 3 | endif 4 | PWD := $(shell pwd) 5 | ARCH ?= arm64 6 | CROSS_COMPILE ?= aarch64-linux-gnu- 7 | 8 | # This specifies the kernel module to be compiled 9 | obj-m += time.o 10 | 11 | # The default action 12 | all: modules 13 | 14 | # The main tasks 15 | modules clean: 16 | make -C $(KERNEL_DIR) \ 17 | ARCH=$(ARCH) \ 18 | CROSS_COMPILE=$(CROSS_COMPILE) \ 19 | SUBDIRS=$(PWD) $@ 20 | -------------------------------------------------------------------------------- /Chapter06/time/time.c: -------------------------------------------------------------------------------- 1 | /* 2 | * Kernel timing functions 3 | */ 4 | 5 | #define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__ 6 | #include 7 | #include 8 | #include 9 | 10 | #define print_time(str, code) \ 11 | do { \ 12 | u64 t0, t1; \ 13 | t0 = ktime_get_real_ns(); \ 14 | code; \ 15 | t1 = ktime_get_real_ns(); \ 16 | pr_info(str " -> %lluns\n", t1 - t0); \ 17 | } while (0) 18 | 19 | /* 20 | * Init & exit stuff 21 | */ 22 | 23 | static int __init time_init(void) 24 | { 25 | pr_info("*delay() functions:\n"); 26 | print_time("10ns", ndelay(10)); 27 | print_time("10000ns", udelay(10)); 28 | print_time("10000000ns", mdelay(10)); 29 | 30 | pr_info("*sleep() functions:\n"); 31 | print_time("10000ns", usleep_range(10, 10)); 32 | print_time("10000000ns", msleep(10)); 33 | print_time("10000000ns", msleep_interruptible(10)); 34 | print_time("10000000000ns", ssleep(10)); 35 | 36 | return -EINVAL; 37 | } 38 | 39 | static void __exit time_exit(void) 40 | { 41 | pr_info("unloaded\n"); 42 | } 43 | 44 | module_init(time_init); 45 | module_exit(time_exit); 46 | 47 | MODULE_LICENSE("GPL"); 48 | MODULE_AUTHOR("Rodolfo Giometti"); 49 | MODULE_DESCRIPTION("Kernel timing functions"); 50 | MODULE_VERSION("0.1"); 51 | -------------------------------------------------------------------------------- /Chapter07/.gitignore: -------------------------------------------------------------------------------- 1 | chrdev_ioctl 2 | chrdev_mmap 3 | chrdev_fasync 4 | chrdev_select 5 | textfile.txt 6 | -------------------------------------------------------------------------------- /Chapter07/chrdev/Makefile: -------------------------------------------------------------------------------- 1 | ifndef KERNEL_DIR 2 | $(error KERNEL_DIR must be set in the command line) 3 | endif 4 | PWD := $(shell pwd) 5 | ARCH ?= arm64 6 | CROSS_COMPILE ?= aarch64-linux-gnu- 7 | 8 | obj-m = chrdev.o 9 | obj-m += chrdev_irq.o 10 | obj-m += chrdev-req.o 11 | 12 | all: modules 13 | 14 | modules clean: 15 | make -C $(KERNEL_DIR) \ 16 | ARCH=$(ARCH) \ 17 | CROSS_COMPILE=$(CROSS_COMPILE) \ 18 | SUBDIRS=$(PWD) $@ 19 | -------------------------------------------------------------------------------- /Chapter07/chrdev/add_mutex_to_chrdev.patch: -------------------------------------------------------------------------------- 1 | diff --git a/chapter_07/chrdev/chrdev.c b/chapter_07/chrdev/chrdev.c 2 | index 8c5f6d8..bb37e4c 100644 3 | --- a/chapter_07/chrdev/chrdev.c 4 | +++ b/chapter_07/chrdev/chrdev.c 5 | @@ -73,6 +73,9 @@ static long chrdev_ioctl(struct file *filp, 6 | dev_info(chrdev->dev, "cmd nr=%d size=%d dir=%x\n", 7 | _IOC_NR(cmd), _IOC_SIZE(cmd), _IOC_DIR(cmd)); 8 | 9 | + /* Grab the mutex */ 10 | + mutex_lock(&chrdev->mux); 11 | + 12 | switch (cmd) { 13 | case CHRDEV_IOC_GETINFO: 14 | dev_info(chrdev->dev, "CHRDEV_IOC_GETINFO\n"); 15 | @@ -81,8 +84,10 @@ static long chrdev_ioctl(struct file *filp, 16 | info.read_only = chrdev->read_only; 17 | 18 | ret = copy_to_user(uarg, &info, sizeof(struct chrdev_info)); 19 | - if (ret) 20 | - return -EFAULT; 21 | + if (ret) { 22 | + ret = -EFAULT; 23 | + goto unlock; 24 | + } 25 | 26 | break; 27 | 28 | @@ -90,16 +95,24 @@ static long chrdev_ioctl(struct file *filp, 29 | dev_info(chrdev->dev, "WDIOC_SET_RDONLY\n"); 30 | 31 | ret = get_user(chrdev->read_only, iuarg); 32 | - if (ret) 33 | - return -EFAULT; 34 | + if (ret) { 35 | + ret = -EFAULT; 36 | + goto unlock; 37 | + } 38 | 39 | break; 40 | 41 | default: 42 | - return -ENOIOCTLCMD; 43 | + ret = -ENOIOCTLCMD; 44 | + goto unlock; 45 | } 46 | + ret = 0; 47 | 48 | - return 0; 49 | +unlock: 50 | + /* Release the mutex */ 51 | + mutex_unlock(&chrdev->mux); 52 | + 53 | + return ret; 54 | } 55 | 56 | static loff_t chrdev_llseek(struct file *filp, loff_t offset, int whence) 57 | @@ -110,6 +123,9 @@ static loff_t chrdev_llseek(struct file *filp, loff_t offset, int whence) 58 | dev_info(chrdev->dev, "should move *ppos=%lld by whence %d off=%lld\n", 59 | filp->f_pos, whence, offset); 60 | 61 | + /* Grab the mutex */ 62 | + mutex_lock(&chrdev->mux); 63 | + 64 | switch (whence) { 65 | case SEEK_SET: 66 | newppos = offset; 67 | @@ -124,15 +140,22 @@ static loff_t chrdev_llseek(struct file *filp, loff_t offset, int whence) 68 | break; 69 | 70 | default: 71 | - return -EINVAL; 72 | + newppos = -EINVAL; 73 | + goto unlock; 74 | } 75 | 76 | - if ((newppos < 0) || (newppos >= BUF_LEN)) 77 | - return -EINVAL; 78 | + if ((newppos < 0) || (newppos >= BUF_LEN)) { 79 | + newppos = -EINVAL; 80 | + goto unlock; 81 | + } 82 | 83 | filp->f_pos = newppos; 84 | dev_info(chrdev->dev, "return *ppos=%lld\n", filp->f_pos); 85 | 86 | +unlock: 87 | + /* Release the mutex */ 88 | + mutex_unlock(&chrdev->mux); 89 | + 90 | return newppos; 91 | } 92 | 93 | @@ -145,18 +168,27 @@ static ssize_t chrdev_read(struct file *filp, 94 | dev_info(chrdev->dev, "should read %ld bytes (*ppos=%lld)\n", 95 | count, *ppos); 96 | 97 | + /* Grab the mutex */ 98 | + mutex_lock(&chrdev->mux); 99 | + 100 | /* Check for end-of-buffer */ 101 | if (*ppos + count >= BUF_LEN) 102 | count = BUF_LEN - *ppos; 103 | 104 | /* Return data to the user space */ 105 | ret = copy_to_user(buf, chrdev->buf + *ppos, count); 106 | - if (ret < 0) 107 | - return -EFAULT; 108 | + if (ret < 0) { 109 | + count = -EFAULT; 110 | + goto unlock; 111 | + } 112 | 113 | *ppos += count; 114 | dev_info(chrdev->dev, "return %ld bytes (*ppos=%lld)\n", count, *ppos); 115 | 116 | +unlock: 117 | + /* Release the mutex */ 118 | + mutex_unlock(&chrdev->mux); 119 | + 120 | return count; 121 | } 122 | 123 | @@ -172,18 +204,27 @@ static ssize_t chrdev_write(struct file *filp, 124 | if (chrdev->read_only) 125 | return -EINVAL; 126 | 127 | + /* Grab the mutex */ 128 | + mutex_lock(&chrdev->mux); 129 | + 130 | /* Check for end-of-buffer */ 131 | if (*ppos + count >= BUF_LEN) 132 | count = BUF_LEN - *ppos; 133 | 134 | /* Get data from the user space */ 135 | ret = copy_from_user(chrdev->buf + *ppos, buf, count); 136 | - if (ret < 0) 137 | - return -EFAULT; 138 | + if (ret < 0) { 139 | + count = -EFAULT; 140 | + goto unlock; 141 | + } 142 | 143 | *ppos += count; 144 | dev_info(chrdev->dev, "got %ld bytes (*ppos=%lld)\n", count, *ppos); 145 | 146 | +unlock: 147 | + /* Release the mutex */ 148 | + mutex_unlock(&chrdev->mux); 149 | + 150 | return count; 151 | } 152 | 153 | @@ -280,6 +321,7 @@ int chrdev_device_register(const char *label, unsigned int id, 154 | chrdev->read_only = read_only; 155 | chrdev->busy = 1; 156 | strncpy(chrdev->label, label, NAME_LEN); 157 | + mutex_init(&chrdev->mux); 158 | 159 | dev_info(chrdev->dev, "chrdev %s with id %d added\n", label, id); 160 | 161 | diff --git a/chapter_07/chrdev/chrdev.h b/chapter_07/chrdev/chrdev.h 162 | index 40a244f..4c8cd34 100644 163 | --- a/chapter_07/chrdev/chrdev.h 164 | +++ b/chapter_07/chrdev/chrdev.h 165 | @@ -3,6 +3,7 @@ 166 | */ 167 | 168 | #include 169 | +#include 170 | #include "chrdev_ioctl.h" 171 | 172 | #define MAX_DEVICES 8 173 | @@ -24,6 +25,8 @@ struct chrdev_device { 174 | struct module *owner; 175 | struct cdev cdev; 176 | struct device *dev; 177 | + 178 | + struct mutex mux; 179 | }; 180 | 181 | /* 182 | -------------------------------------------------------------------------------- /Chapter07/chrdev/chrdev-req.c: -------------------------------------------------------------------------------- 1 | /* 2 | * chrdev req 3 | */ 4 | 5 | #define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__ 6 | #include 7 | #include 8 | #include 9 | #include 10 | #include 11 | #include 12 | #include 13 | 14 | #include "chrdev.h" 15 | 16 | /* 17 | * Platform driver stuff 18 | */ 19 | 20 | static int chrdev_req_probe(struct platform_device *pdev) 21 | { 22 | struct device *dev = &pdev->dev; 23 | struct fwnode_handle *child; 24 | struct module *owner = THIS_MODULE; 25 | int count, ret; 26 | 27 | count = device_get_child_node_count(dev); 28 | if (count == 0) 29 | return -ENODEV; 30 | if (count > MAX_DEVICES) 31 | return -ENOMEM; 32 | 33 | device_for_each_child_node(dev, child) { 34 | const char *label; 35 | unsigned int id, ro; 36 | 37 | /* 38 | * Get device's properties 39 | */ 40 | 41 | if (fwnode_property_present(child, "reg")) { 42 | fwnode_property_read_u32(child, "reg", &id); 43 | } else { 44 | dev_err(dev, "property \"reg\" not present! Skipped"); 45 | continue; 46 | } 47 | if (fwnode_property_present(child, "label")) { 48 | fwnode_property_read_string(child, "label", &label); 49 | } else { 50 | dev_err(dev, "property \"label\" not present! Skipped"); 51 | continue; 52 | } 53 | ro = fwnode_property_present(child, "read-only"); 54 | 55 | /* Register the new chr device */ 56 | ret = chrdev_device_register(label, id, ro, owner, dev); 57 | if (ret) { 58 | dev_err(dev, "unable to register"); 59 | } 60 | } 61 | 62 | return 0; 63 | } 64 | 65 | static int chrdev_req_remove(struct platform_device *pdev) 66 | { 67 | struct device *dev = &pdev->dev; 68 | struct fwnode_handle *child; 69 | int ret; 70 | 71 | device_for_each_child_node(dev, child) { 72 | const char *label; 73 | int id; 74 | 75 | /* 76 | * Get device's properties 77 | */ 78 | 79 | if (fwnode_property_present(child, "reg")) 80 | fwnode_property_read_u32(child, "reg", &id); 81 | else 82 | BUG(); 83 | if (fwnode_property_present(child, "label")) 84 | fwnode_property_read_string(child, "label", &label); 85 | else 86 | BUG(); 87 | 88 | /* Register the new chr device */ 89 | ret = chrdev_device_unregister(label, id); 90 | if (ret) 91 | dev_err(dev, "unable to unregister"); 92 | } 93 | 94 | return 0; 95 | } 96 | 97 | static const struct of_device_id of_chrdev_req_match[] = { 98 | { 99 | .compatible = "ldddc,chrdev", 100 | }, 101 | { /* sentinel */ } 102 | }; 103 | MODULE_DEVICE_TABLE(of, of_chrdev_req_match); 104 | 105 | static struct platform_driver chrdev_req_driver = { 106 | .probe = chrdev_req_probe, 107 | .remove = chrdev_req_remove, 108 | .driver = { 109 | .name = "chrdev-req", 110 | .of_match_table = of_chrdev_req_match, 111 | }, 112 | }; 113 | module_platform_driver(chrdev_req_driver); 114 | 115 | MODULE_LICENSE("GPL"); 116 | MODULE_AUTHOR("Rodolfo Giometti"); 117 | MODULE_DESCRIPTION("chrdev request"); 118 | -------------------------------------------------------------------------------- /Chapter07/chrdev/chrdev.c: -------------------------------------------------------------------------------- 1 | /* 2 | * chrdev 3 | */ 4 | 5 | #define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__ 6 | #include 7 | #include 8 | #include 9 | #include 10 | #include 11 | #include 12 | 13 | 14 | #include "chrdev.h" 15 | 16 | /* 17 | * Local variables 18 | */ 19 | 20 | static dev_t chrdev_devt; 21 | static struct class *chrdev_class; 22 | 23 | struct chrdev_device chrdev_array[MAX_DEVICES]; 24 | 25 | /* 26 | * Methods 27 | */ 28 | 29 | static int chrdev_mmap(struct file *filp, struct vm_area_struct *vma) 30 | { 31 | struct chrdev_device *chrdev = filp->private_data; 32 | size_t size = vma->vm_end - vma->vm_start; 33 | phys_addr_t offset = (phys_addr_t) vma->vm_pgoff << PAGE_SHIFT; 34 | unsigned long pfn; 35 | 36 | /* Does it even fit in phys_addr_t? */ 37 | if (offset >> PAGE_SHIFT != vma->vm_pgoff) 38 | return -EINVAL; 39 | 40 | /* We cannot mmap too big areas */ 41 | if ((offset > BUF_LEN) || (size > BUF_LEN - offset)) 42 | return -EINVAL; 43 | 44 | /* Get the physical address belong the virtual kernel address */ 45 | pfn = virt_to_phys(chrdev->buf) >> PAGE_SHIFT; 46 | 47 | dev_info(chrdev->dev, "mmap vma=%lx pfn=%lx size=%lx", 48 | vma->vm_start, pfn, size); 49 | 50 | /* Remap-pfn-range will mark the range VM_IO */ 51 | if (remap_pfn_range(vma, vma->vm_start, 52 | pfn, size, 53 | vma->vm_page_prot)) 54 | return -EAGAIN; 55 | 56 | return 0; 57 | } 58 | 59 | static long chrdev_ioctl(struct file *filp, 60 | unsigned int cmd, unsigned long arg) 61 | { 62 | struct chrdev_device *chrdev = filp->private_data; 63 | struct chrdev_info info; 64 | void __user *uarg = (void __user *) arg; 65 | int __user *iuarg = (int __user *) arg; 66 | int ret; 67 | 68 | /* Get some command information */ 69 | if (_IOC_TYPE(cmd) != CHRDEV_IOCTL_BASE) { 70 | dev_err(chrdev->dev, "command %x is not for us!\n", cmd); 71 | return -EINVAL; 72 | } 73 | dev_info(chrdev->dev, "cmd nr=%d size=%d dir=%x\n", 74 | _IOC_NR(cmd), _IOC_SIZE(cmd), _IOC_DIR(cmd)); 75 | 76 | switch (cmd) { 77 | case CHRDEV_IOC_GETINFO: 78 | dev_info(chrdev->dev, "CHRDEV_IOC_GETINFO\n"); 79 | 80 | strncpy(info.label, chrdev->label, NAME_LEN); 81 | info.read_only = chrdev->read_only; 82 | 83 | ret = copy_to_user(uarg, &info, sizeof(struct chrdev_info)); 84 | if (ret) 85 | return -EFAULT; 86 | 87 | break; 88 | 89 | case WDIOC_SET_RDONLY: 90 | dev_info(chrdev->dev, "WDIOC_SET_RDONLY\n"); 91 | 92 | ret = get_user(chrdev->read_only, iuarg); 93 | if (ret) 94 | return -EFAULT; 95 | 96 | break; 97 | 98 | default: 99 | return -ENOIOCTLCMD; 100 | } 101 | 102 | return 0; 103 | } 104 | 105 | static loff_t chrdev_llseek(struct file *filp, loff_t offset, int whence) 106 | { 107 | struct chrdev_device *chrdev = filp->private_data; 108 | loff_t newppos; 109 | 110 | dev_info(chrdev->dev, "should move *ppos=%lld by whence %d off=%lld\n", 111 | filp->f_pos, whence, offset); 112 | 113 | switch (whence) { 114 | case SEEK_SET: 115 | newppos = offset; 116 | break; 117 | 118 | case SEEK_CUR: 119 | newppos = filp->f_pos + offset; 120 | break; 121 | 122 | case SEEK_END: 123 | newppos = BUF_LEN + offset; 124 | break; 125 | 126 | default: 127 | return -EINVAL; 128 | } 129 | 130 | if ((newppos < 0) || (newppos >= BUF_LEN)) 131 | return -EINVAL; 132 | 133 | filp->f_pos = newppos; 134 | dev_info(chrdev->dev, "return *ppos=%lld\n", filp->f_pos); 135 | 136 | return newppos; 137 | } 138 | 139 | static ssize_t chrdev_read(struct file *filp, 140 | char __user *buf, size_t count, loff_t *ppos) 141 | { 142 | struct chrdev_device *chrdev = filp->private_data; 143 | int ret; 144 | 145 | dev_info(chrdev->dev, "should read %ld bytes (*ppos=%lld)\n", 146 | count, *ppos); 147 | 148 | /* Check for end-of-buffer */ 149 | if (*ppos + count >= BUF_LEN) 150 | count = BUF_LEN - *ppos; 151 | 152 | /* Return data to the user space */ 153 | ret = copy_to_user(buf, chrdev->buf + *ppos, count); 154 | if (ret < 0) 155 | return -EFAULT; 156 | 157 | *ppos += count; 158 | dev_info(chrdev->dev, "return %ld bytes (*ppos=%lld)\n", count, *ppos); 159 | 160 | return count; 161 | } 162 | 163 | static ssize_t chrdev_write(struct file *filp, 164 | const char __user *buf, size_t count, loff_t *ppos) 165 | { 166 | struct chrdev_device *chrdev = filp->private_data; 167 | int ret; 168 | 169 | dev_info(chrdev->dev, "should write %ld bytes (*ppos=%lld)\n", 170 | count, *ppos); 171 | 172 | if (chrdev->read_only) 173 | return -EINVAL; 174 | 175 | /* Check for end-of-buffer */ 176 | if (*ppos + count >= BUF_LEN) 177 | count = BUF_LEN - *ppos; 178 | 179 | /* Get data from the user space */ 180 | ret = copy_from_user(chrdev->buf + *ppos, buf, count); 181 | if (ret < 0) 182 | return -EFAULT; 183 | 184 | *ppos += count; 185 | dev_info(chrdev->dev, "got %ld bytes (*ppos=%lld)\n", count, *ppos); 186 | 187 | return count; 188 | } 189 | 190 | static int chrdev_open(struct inode *inode, struct file *filp) 191 | { 192 | struct chrdev_device *chrdev = container_of(inode->i_cdev, 193 | struct chrdev_device, cdev); 194 | filp->private_data = chrdev; 195 | kobject_get(&chrdev->dev->kobj); 196 | 197 | dev_info(chrdev->dev, "chrdev (id=%d) opened\n", chrdev->id); 198 | 199 | return 0; 200 | } 201 | 202 | static int chrdev_release(struct inode *inode, struct file *filp) 203 | { 204 | struct chrdev_device *chrdev = container_of(inode->i_cdev, 205 | struct chrdev_device, cdev); 206 | kobject_put(&chrdev->dev->kobj); 207 | filp->private_data = NULL; 208 | 209 | dev_info(chrdev->dev, "chrdev (id=%d) released\n", chrdev->id); 210 | 211 | return 0; 212 | } 213 | 214 | static const struct file_operations chrdev_fops = { 215 | .owner = THIS_MODULE, 216 | .mmap = chrdev_mmap, 217 | .unlocked_ioctl = chrdev_ioctl, 218 | .llseek = chrdev_llseek, 219 | .read = chrdev_read, 220 | .write = chrdev_write, 221 | .open = chrdev_open, 222 | .release = chrdev_release 223 | }; 224 | 225 | /* 226 | * Exported functions 227 | */ 228 | 229 | int chrdev_device_register(const char *label, unsigned int id, 230 | unsigned int read_only, 231 | struct module *owner, struct device *parent) 232 | { 233 | struct chrdev_device *chrdev; 234 | dev_t devt; 235 | int ret; 236 | 237 | /* First check if we are allocating a valid device... */ 238 | if (id >= MAX_DEVICES) { 239 | pr_err("invalid id %d\n", id); 240 | return -EINVAL; 241 | } 242 | chrdev = &chrdev_array[id]; 243 | 244 | /* ... then check if we have not busy id */ 245 | if (chrdev->busy) { 246 | pr_err("id %d\n is busy", id); 247 | return -EBUSY; 248 | } 249 | 250 | /* First try to allocate memory for internal buffer */ 251 | chrdev->buf = kzalloc(BUF_LEN, GFP_KERNEL); 252 | if (!chrdev->buf) { 253 | dev_err(chrdev->dev, "cannot allocate memory buffer!\n"); 254 | return -ENOMEM; 255 | } 256 | 257 | /* Create the device and initialize its data */ 258 | cdev_init(&chrdev->cdev, &chrdev_fops); 259 | chrdev->cdev.owner = owner; 260 | 261 | devt = MKDEV(MAJOR(chrdev_devt), id); 262 | ret = cdev_add(&chrdev->cdev, devt, 1); 263 | if (ret) { 264 | pr_err("failed to add char device %s at %d:%d\n", 265 | label, MAJOR(chrdev_devt), id); 266 | goto kfree_buf; 267 | } 268 | 269 | chrdev->dev = device_create(chrdev_class, parent, devt, chrdev, 270 | "%s@%d", label, id); 271 | if (IS_ERR(chrdev->dev)) { 272 | pr_err("unable to create device %s\n", label); 273 | ret = PTR_ERR(chrdev->dev); 274 | goto del_cdev; 275 | } 276 | dev_set_drvdata(chrdev->dev, chrdev); 277 | 278 | /* Init the chrdev data */ 279 | chrdev->id = id; 280 | chrdev->read_only = read_only; 281 | chrdev->busy = 1; 282 | strncpy(chrdev->label, label, NAME_LEN); 283 | 284 | dev_info(chrdev->dev, "chrdev %s with id %d added\n", label, id); 285 | 286 | return 0; 287 | 288 | del_cdev: 289 | cdev_del(&chrdev->cdev); 290 | kfree_buf: 291 | kfree(chrdev->buf); 292 | 293 | return ret; 294 | } 295 | EXPORT_SYMBOL(chrdev_device_register); 296 | 297 | int chrdev_device_unregister(const char *label, unsigned int id) 298 | { 299 | struct chrdev_device *chrdev; 300 | 301 | /* First check if we are deallocating a valid device... */ 302 | if (id >= MAX_DEVICES) { 303 | pr_err("invalid id %d\n", id); 304 | return -EINVAL; 305 | } 306 | chrdev = &chrdev_array[id]; 307 | 308 | /* ... then check if device is actualy allocated */ 309 | if (!chrdev->busy || strcmp(chrdev->label, label)) { 310 | pr_err("id %d is not busy or label %s is not known\n", 311 | id, label); 312 | return -EINVAL; 313 | } 314 | 315 | /* Deinit the chrdev data */ 316 | chrdev->id = 0; 317 | chrdev->busy = 0; 318 | 319 | dev_info(chrdev->dev, "chrdev %s with id %d removed\n", label, id); 320 | 321 | /* Free allocated memory */ 322 | kfree(chrdev->buf); 323 | 324 | /* Dealocate the device */ 325 | device_destroy(chrdev_class, chrdev->dev->devt); 326 | cdev_del(&chrdev->cdev); 327 | 328 | return 0; 329 | } 330 | EXPORT_SYMBOL(chrdev_device_unregister); 331 | 332 | /* 333 | * Module stuff 334 | */ 335 | 336 | static int __init chrdev_init(void) 337 | { 338 | int ret; 339 | 340 | /* Create the new class for the chrdev devices */ 341 | chrdev_class = class_create(THIS_MODULE, "chrdev"); 342 | if (!chrdev_class) { 343 | pr_err("chrdev: failed to allocate class\n"); 344 | return -ENOMEM; 345 | } 346 | 347 | /* Allocate a region for character devices */ 348 | ret = alloc_chrdev_region(&chrdev_devt, 0, MAX_DEVICES, "chrdev"); 349 | if (ret < 0) { 350 | pr_err("failed to allocate char device region\n"); 351 | goto remove_class; 352 | } 353 | 354 | pr_info("got major %d\n", MAJOR(chrdev_devt)); 355 | 356 | return 0; 357 | 358 | remove_class: 359 | class_destroy(chrdev_class); 360 | 361 | return ret; 362 | } 363 | 364 | static void __exit chrdev_exit(void) 365 | { 366 | unregister_chrdev_region(chrdev_devt, MAX_DEVICES); 367 | class_destroy(chrdev_class); 368 | } 369 | 370 | module_init(chrdev_init); 371 | module_exit(chrdev_exit); 372 | 373 | MODULE_LICENSE("GPL"); 374 | MODULE_AUTHOR("Rodolfo Giometti"); 375 | MODULE_DESCRIPTION("chardev"); 376 | -------------------------------------------------------------------------------- /Chapter07/chrdev/chrdev.h: -------------------------------------------------------------------------------- 1 | /* 2 | * Chrdev include file 3 | */ 4 | 5 | #include 6 | #include "chrdev_ioctl.h" 7 | 8 | #define MAX_DEVICES 8 9 | #define NAME_LEN CHRDEV_NAME_LEN 10 | #define BUF_LEN PAGE_SIZE 11 | 12 | /* 13 | * Chrdev basic structs 14 | */ 15 | 16 | /* Main struct */ 17 | struct chrdev_device { 18 | char label[NAME_LEN]; 19 | unsigned int busy : 1; 20 | char *buf; 21 | int read_only; 22 | 23 | unsigned int id; 24 | struct module *owner; 25 | struct cdev cdev; 26 | struct device *dev; 27 | }; 28 | 29 | /* 30 | * Exported functions 31 | */ 32 | 33 | #define to_class_dev(obj) container_of((obj), struct class_device, kobj) 34 | #define to_chrdev_device(obj) container_of((obj), struct chrdev_device, class) 35 | 36 | extern int chrdev_device_register(const char *label, unsigned int id, 37 | unsigned int read_only, 38 | struct module *owner, struct device *parent); 39 | extern int chrdev_device_unregister(const char *label, unsigned int id); 40 | -------------------------------------------------------------------------------- /Chapter07/chrdev/chrdev_ioctl.h: -------------------------------------------------------------------------------- 1 | /* 2 | * Chrdev ioctl() include file 3 | */ 4 | 5 | #include 6 | #include 7 | 8 | #define CHRDEV_IOCTL_BASE 'C' 9 | #define CHRDEV_NAME_LEN 32 10 | 11 | struct chrdev_info { 12 | char label[CHRDEV_NAME_LEN]; 13 | int read_only; 14 | }; 15 | 16 | /* 17 | * The ioctl() commands 18 | */ 19 | 20 | #define CHRDEV_IOC_GETINFO _IOR(CHRDEV_IOCTL_BASE, 0, struct chrdev_info) 21 | #define WDIOC_SET_RDONLY _IOW(CHRDEV_IOCTL_BASE, 1, int) 22 | -------------------------------------------------------------------------------- /Chapter07/chrdev/chrdev_irq.c: -------------------------------------------------------------------------------- 1 | /* 2 | * chrdev 3 | */ 4 | 5 | #define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__ 6 | #include 7 | #include 8 | #include 9 | #include 10 | #include 11 | #include 12 | #include 13 | 14 | #include "chrdev_irq.h" 15 | 16 | /* 17 | * Module parameter 18 | */ 19 | 20 | static int delay_ns = 1000000000; 21 | module_param(delay_ns, int, S_IRUSR | S_IWUSR); 22 | MODULE_PARM_DESC(delay_ns, "kernel timer delay is ns"); 23 | 24 | /* 25 | * Local variables 26 | */ 27 | 28 | static dev_t chrdev_devt; 29 | static struct class *chrdev_class; 30 | 31 | struct chrdev_device chrdev_array[MAX_DEVICES]; 32 | 33 | /* 34 | * Dummy function to generate data 35 | */ 36 | 37 | static char get_new_char(void) 38 | { 39 | static char d = 'A' - 1; 40 | 41 | if (++d == ('Z' + 1)) 42 | d = 'A'; 43 | 44 | return d; 45 | } 46 | 47 | /* 48 | * Circular buffer management functions 49 | */ 50 | 51 | static inline bool cbuf_is_empty(size_t head, size_t tail, size_t len) 52 | { 53 | return head == tail; 54 | } 55 | 56 | static inline bool cbuf_is_full(size_t head, size_t tail, size_t len) 57 | { 58 | head = (head + 1) % len; 59 | return head == tail; 60 | } 61 | 62 | static inline size_t cbuf_count_to_end(size_t head, size_t tail, size_t len) 63 | { 64 | if (head >= tail) 65 | return head - tail; 66 | else 67 | return len - tail + head; 68 | } 69 | 70 | static inline size_t cbuf_space_to_end(size_t head, size_t tail, size_t len) 71 | { 72 | if (head >= tail) 73 | return len - head + tail - 1; 74 | else 75 | return tail - head - 1; 76 | } 77 | 78 | static inline void cbuf_pointer_move(size_t *ptr, size_t n, size_t len) 79 | { 80 | *ptr = (*ptr + n) % len; 81 | } 82 | 83 | /* 84 | * (simulation of) IRQ handler 85 | */ 86 | 87 | static enum hrtimer_restart chrdev_timer_handler(struct hrtimer *ptr) 88 | { 89 | struct chrdev_device *chrdev = container_of(ptr, 90 | struct chrdev_device, timer); 91 | 92 | /* Grab the lock */ 93 | spin_lock(&chrdev->lock); 94 | 95 | /* Now we should check if we have some space to 96 | * save incoming data, otherwise they must be dropped... 97 | */ 98 | if (!cbuf_is_full(chrdev->head, chrdev->tail, BUF_LEN)) { 99 | chrdev->buf[chrdev->head] = get_new_char(); 100 | 101 | cbuf_pointer_move(&chrdev->head, 1, BUF_LEN); 102 | } 103 | 104 | /* Release the lock */ 105 | spin_unlock(&chrdev->lock); 106 | 107 | /* Wake up any possible sleeping process */ 108 | wake_up_interruptible(&chrdev->queue); 109 | kill_fasync(&chrdev->fasync_queue, SIGIO, POLL_IN); 110 | 111 | /* Now forward the expiration time and ask to be rescheduled */ 112 | hrtimer_forward_now(&chrdev->timer, ns_to_ktime(delay_ns)); 113 | return HRTIMER_RESTART; 114 | } 115 | 116 | /* 117 | * Methods 118 | */ 119 | 120 | static int chrdev_fasync(int fd, struct file *filp, int on) 121 | { 122 | struct chrdev_device *chrdev = filp->private_data; 123 | 124 | return fasync_helper(fd, filp, on, &chrdev->fasync_queue); 125 | } 126 | 127 | static __poll_t chrdev_poll(struct file *filp, poll_table *wait) 128 | { 129 | struct chrdev_device *chrdev = filp->private_data; 130 | __poll_t mask = 0; 131 | 132 | poll_wait(filp, &chrdev->queue, wait); 133 | 134 | /* Grab the mutex */ 135 | mutex_lock(&chrdev->mux); 136 | 137 | if (!cbuf_is_empty(chrdev->head, chrdev->tail, BUF_LEN)) 138 | mask |= EPOLLIN | EPOLLRDNORM; 139 | 140 | /* Release the mutex */ 141 | mutex_unlock(&chrdev->mux); 142 | 143 | return mask; 144 | } 145 | 146 | static ssize_t chrdev_read(struct file *filp, 147 | char __user *buf, size_t count, loff_t *ppos) 148 | { 149 | struct chrdev_device *chrdev = filp->private_data; 150 | unsigned long flags; 151 | char tmp[256]; 152 | size_t n; 153 | int ret; 154 | 155 | dev_info(chrdev->dev, "should read %ld bytes\n", count); 156 | 157 | /* Grab the mutex */ 158 | mutex_lock(&chrdev->mux); 159 | 160 | /* Check for some data into read buffer */ 161 | if (filp->f_flags & O_NONBLOCK) { 162 | if (cbuf_is_empty(chrdev->head, chrdev->tail, BUF_LEN)) { 163 | ret = -EAGAIN; 164 | goto unlock; 165 | } 166 | } else if (wait_event_interruptible(chrdev->queue, 167 | !cbuf_is_empty(chrdev->head, chrdev->tail, BUF_LEN))) { 168 | count = -ERESTARTSYS; 169 | goto unlock; 170 | } 171 | 172 | /* Grab the lock */ 173 | spin_lock_irqsave(&chrdev->lock, flags); 174 | 175 | /* Get data from the circular buffer */ 176 | n = cbuf_count_to_end(chrdev->head, chrdev->tail, BUF_LEN); 177 | count = min(count, n); 178 | memcpy(tmp, &chrdev->buf[chrdev->tail], count); 179 | 180 | /* Release the lock */ 181 | spin_unlock_irqrestore(&chrdev->lock, flags); 182 | 183 | /* Return data to the user space */ 184 | ret = copy_to_user(buf, tmp, count); 185 | if (ret < 0) { 186 | ret = -EFAULT; 187 | goto unlock; 188 | } 189 | 190 | /* Now we can safely move the tail pointer */ 191 | cbuf_pointer_move(&chrdev->tail, count, BUF_LEN); 192 | dev_info(chrdev->dev, "return %ld bytes\n", count); 193 | 194 | unlock: 195 | /* Release the mutex */ 196 | mutex_unlock(&chrdev->mux); 197 | 198 | return count; 199 | } 200 | 201 | static int chrdev_open(struct inode *inode, struct file *filp) 202 | { 203 | struct chrdev_device *chrdev = container_of(inode->i_cdev, 204 | struct chrdev_device, cdev); 205 | filp->private_data = chrdev; 206 | kobject_get(&chrdev->dev->kobj); 207 | 208 | dev_info(chrdev->dev, "chrdev (id=%d) opened\n", chrdev->id); 209 | 210 | return 0; 211 | } 212 | 213 | static int chrdev_release(struct inode *inode, struct file *filp) 214 | { 215 | struct chrdev_device *chrdev = container_of(inode->i_cdev, 216 | struct chrdev_device, cdev); 217 | kobject_put(&chrdev->dev->kobj); 218 | filp->private_data = NULL; 219 | 220 | dev_info(chrdev->dev, "chrdev (id=%d) released\n", chrdev->id); 221 | 222 | return 0; 223 | } 224 | 225 | static const struct file_operations chrdev_fops = { 226 | .owner = THIS_MODULE, 227 | .fasync = chrdev_fasync, 228 | .poll = chrdev_poll, 229 | .llseek = no_llseek, 230 | .read = chrdev_read, 231 | .open = chrdev_open, 232 | .release = chrdev_release 233 | }; 234 | 235 | /* 236 | * Exported functions 237 | */ 238 | 239 | int chrdev_device_register(const char *label, unsigned int id, 240 | unsigned int read_only, 241 | struct module *owner, struct device *parent) 242 | { 243 | struct chrdev_device *chrdev; 244 | dev_t devt; 245 | int ret; 246 | 247 | /* First check if we are allocating a valid device... */ 248 | if (id >= MAX_DEVICES) { 249 | pr_err("invalid id %d\n", id); 250 | return -EINVAL; 251 | } 252 | chrdev = &chrdev_array[id]; 253 | 254 | /* ... then check if we have not busy id */ 255 | if (chrdev->busy) { 256 | pr_err("id %d\n is busy", id); 257 | return -EBUSY; 258 | } 259 | 260 | /* First try to allocate memory for internal buffer */ 261 | chrdev->buf = kzalloc(BUF_LEN, GFP_KERNEL); 262 | if (!chrdev->buf) { 263 | dev_err(chrdev->dev, "cannot allocate memory buffer!\n"); 264 | return -ENOMEM; 265 | } 266 | 267 | /* Create the device and initialize its data */ 268 | cdev_init(&chrdev->cdev, &chrdev_fops); 269 | chrdev->cdev.owner = owner; 270 | 271 | devt = MKDEV(MAJOR(chrdev_devt), id); 272 | ret = cdev_add(&chrdev->cdev, devt, 1); 273 | if (ret) { 274 | pr_err("failed to add char device %s at %d:%d\n", 275 | label, MAJOR(chrdev_devt), id); 276 | goto kfree_buf; 277 | } 278 | 279 | chrdev->dev = device_create(chrdev_class, parent, devt, chrdev, 280 | "%s@%d", label, id); 281 | if (IS_ERR(chrdev->dev)) { 282 | pr_err("unable to create device %s\n", label); 283 | ret = PTR_ERR(chrdev->dev); 284 | goto del_cdev; 285 | } 286 | dev_set_drvdata(chrdev->dev, chrdev); 287 | 288 | /* Init the chrdev data */ 289 | chrdev->id = id; 290 | chrdev->read_only = read_only; 291 | chrdev->busy = 1; 292 | strncpy(chrdev->label, label, NAME_LEN); 293 | mutex_init(&chrdev->mux); 294 | spin_lock_init(&chrdev->lock); 295 | init_waitqueue_head(&chrdev->queue); 296 | chrdev->head = chrdev->tail = 0; 297 | chrdev->fasync_queue = NULL; 298 | 299 | /* Setup and start the hires timer */ 300 | hrtimer_init(&chrdev->timer, CLOCK_MONOTONIC, 301 | HRTIMER_MODE_REL | HRTIMER_MODE_SOFT); 302 | chrdev->timer.function = chrdev_timer_handler; 303 | hrtimer_start(&chrdev->timer, ns_to_ktime(delay_ns), 304 | HRTIMER_MODE_REL | HRTIMER_MODE_SOFT); 305 | 306 | 307 | dev_info(chrdev->dev, "chrdev %s with id %d added\n", label, id); 308 | 309 | return 0; 310 | 311 | del_cdev: 312 | cdev_del(&chrdev->cdev); 313 | kfree_buf: 314 | kfree(chrdev->buf); 315 | 316 | return ret; 317 | } 318 | EXPORT_SYMBOL(chrdev_device_register); 319 | 320 | int chrdev_device_unregister(const char *label, unsigned int id) 321 | { 322 | struct chrdev_device *chrdev; 323 | 324 | /* First check if we are deallocating a valid device... */ 325 | if (id >= MAX_DEVICES) { 326 | pr_err("invalid id %d\n", id); 327 | return -EINVAL; 328 | } 329 | chrdev = &chrdev_array[id]; 330 | 331 | /* ... then check if device is actualy allocated */ 332 | if (!chrdev->busy || strcmp(chrdev->label, label)) { 333 | pr_err("id %d is not busy or label %s is not known\n", 334 | id, label); 335 | return -EINVAL; 336 | } 337 | 338 | /* Stop the timer */ 339 | hrtimer_cancel(&chrdev->timer); 340 | 341 | /* Deinit the chrdev data */ 342 | chrdev->id = 0; 343 | chrdev->busy = 0; 344 | 345 | dev_info(chrdev->dev, "chrdev %s with id %d removed\n", label, id); 346 | 347 | /* Free allocated memory */ 348 | kfree(chrdev->buf); 349 | 350 | /* Dealocate the device */ 351 | device_destroy(chrdev_class, chrdev->dev->devt); 352 | cdev_del(&chrdev->cdev); 353 | 354 | return 0; 355 | } 356 | EXPORT_SYMBOL(chrdev_device_unregister); 357 | 358 | /* 359 | * Module stuff 360 | */ 361 | 362 | static int __init chrdev_init(void) 363 | { 364 | int ret; 365 | 366 | /* Create the new class for the chrdev devices */ 367 | chrdev_class = class_create(THIS_MODULE, "chrdev"); 368 | if (!chrdev_class) { 369 | pr_err("chrdev: failed to allocate class\n"); 370 | return -ENOMEM; 371 | } 372 | 373 | /* Allocate a region for character devices */ 374 | ret = alloc_chrdev_region(&chrdev_devt, 0, MAX_DEVICES, "chrdev"); 375 | if (ret < 0) { 376 | pr_err("failed to allocate char device region\n"); 377 | goto remove_class; 378 | } 379 | 380 | pr_info("got major %d\n", MAJOR(chrdev_devt)); 381 | 382 | return 0; 383 | 384 | remove_class: 385 | class_destroy(chrdev_class); 386 | 387 | return ret; 388 | } 389 | 390 | static void __exit chrdev_exit(void) 391 | { 392 | unregister_chrdev_region(chrdev_devt, MAX_DEVICES); 393 | class_destroy(chrdev_class); 394 | } 395 | 396 | module_init(chrdev_init); 397 | module_exit(chrdev_exit); 398 | 399 | MODULE_LICENSE("GPL"); 400 | MODULE_AUTHOR("Rodolfo Giometti"); 401 | MODULE_DESCRIPTION("chardev"); 402 | -------------------------------------------------------------------------------- /Chapter07/chrdev/chrdev_irq.h: -------------------------------------------------------------------------------- 1 | /* 2 | * Chrdev include file 3 | */ 4 | 5 | #include 6 | #include 7 | #include 8 | #include 9 | #include 10 | 11 | #define MAX_DEVICES 8 12 | #define NAME_LEN 32 13 | #define BUF_LEN PAGE_SIZE 14 | 15 | /* 16 | * Chrdev basic structs 17 | */ 18 | 19 | /* Main struct */ 20 | struct chrdev_device { 21 | char label[NAME_LEN]; 22 | unsigned int busy : 1; 23 | char *buf; 24 | size_t head, tail; 25 | int read_only; 26 | 27 | unsigned int id; 28 | struct module *owner; 29 | struct cdev cdev; 30 | struct device *dev; 31 | 32 | struct mutex mux; 33 | struct spinlock lock; 34 | struct wait_queue_head queue; 35 | struct hrtimer timer; 36 | struct fasync_struct *fasync_queue; 37 | }; 38 | 39 | /* 40 | * Exported functions 41 | */ 42 | 43 | #define to_class_dev(obj) container_of((obj), struct class_device, kobj) 44 | #define to_chrdev_device(obj) container_of((obj), struct chrdev_device, class) 45 | 46 | extern int chrdev_device_register(const char *label, unsigned int id, 47 | unsigned int read_only, 48 | struct module *owner, struct device *parent); 49 | extern int chrdev_device_unregister(const char *label, unsigned int id); 50 | -------------------------------------------------------------------------------- /Chapter07/chrdev/modify_lseek_to_chrdev_test.patch: -------------------------------------------------------------------------------- 1 | diff --git a/chapter_03/chrdev_test.c b/chapter_03/chrdev_test.c 2 | index 94e04e0..3e8420d 100644 3 | --- a/chapter_03/chrdev_test.c 4 | +++ b/chapter_03/chrdev_test.c 5 | @@ -55,6 +55,13 @@ int main(int argc, char *argv[]) 6 | dump("data written are: ", buf + c, n); 7 | } 8 | 9 | + ret = lseek(fd, SEEK_SET, 0); 10 | + if (ret < 0) { 11 | + perror("lseek"); 12 | + exit(EXIT_FAILURE); 13 | + } 14 | + printf("*ppos moved to 0\n"); 15 | + 16 | for (c = 0; c < sizeof(buf); c += n) { 17 | ret = read(fd, buf, sizeof(buf)); 18 | if (ret == 0) { 19 | -------------------------------------------------------------------------------- /Chapter07/chrdev_fasync.c: -------------------------------------------------------------------------------- 1 | /* 2 | * chrdev fasync() testing program 3 | */ 4 | 5 | #include 6 | #include 7 | #include 8 | #include 9 | #include 10 | #include 11 | #include 12 | #define __USE_GNU 13 | #include 14 | 15 | int fd; 16 | 17 | void sigio_handler(int unused) { 18 | char c; 19 | int ret; 20 | 21 | ret = read(fd, &c, 1); 22 | if (ret < 0) { 23 | perror("read"); 24 | exit(EXIT_FAILURE); 25 | } 26 | ret = write(STDOUT_FILENO, &c, 1); 27 | if (ret < 0) { 28 | perror("write"); 29 | exit(EXIT_FAILURE); 30 | } 31 | } 32 | 33 | int main(int argc, char *argv[]) 34 | { 35 | sighandler_t sigh; 36 | long flags; 37 | char c; 38 | int ret; 39 | 40 | if (argc < 2) { 41 | fprintf(stderr, "usage: %s \n", argv[0]); 42 | exit(EXIT_FAILURE); 43 | } 44 | 45 | ret = open(argv[1], O_RDWR); 46 | if (ret < 0) { 47 | perror("open"); 48 | exit(EXIT_FAILURE); 49 | } 50 | printf("file %s opened\n", argv[1]); 51 | fd = ret; 52 | 53 | /* Try to install the signal handler and the fasync stuff */ 54 | sigh = signal(SIGIO, sigio_handler); 55 | if (sigh == SIG_ERR) { 56 | perror("signal"); 57 | exit(EXIT_FAILURE); 58 | } 59 | ret = fcntl(fd, F_SETOWN, getpid()); 60 | if (ret < 0) { 61 | perror("fcntl(..., F_SETOWN, ...)"); 62 | exit(EXIT_FAILURE); 63 | } 64 | flags = fcntl(fd, F_GETFL); 65 | if (flags < 0) { 66 | perror("fcntl(..., F_GETFL)"); 67 | exit(EXIT_FAILURE); 68 | } 69 | ret = fcntl(fd, F_SETFL, flags | FASYNC); 70 | if (flags < 0) { 71 | perror("fcntl(..., F_SETFL, ...)"); 72 | exit(EXIT_FAILURE); 73 | } 74 | 75 | /* Now we can wait for data while waiting data from stdin */ 76 | while (1) { 77 | ret = read(STDOUT_FILENO, &c, 1); 78 | if (ret < 0) { 79 | perror("read"); 80 | exit(EXIT_FAILURE); 81 | } 82 | printf("got '%c' from stdin!\n", c); 83 | } 84 | 85 | signal(SIGIO, NULL); 86 | close(fd); 87 | 88 | return 0; 89 | } 90 | -------------------------------------------------------------------------------- /Chapter07/chrdev_ioctl.c: -------------------------------------------------------------------------------- 1 | /* 2 | * chrdev ioctl() testing program 3 | */ 4 | 5 | #include 6 | #include 7 | #include 8 | #include 9 | #include 10 | #include 11 | #include 12 | #include 13 | 14 | #include "chrdev_ioctl.h" 15 | 16 | int main(int argc, char *argv[]) 17 | { 18 | int fd; 19 | struct chrdev_info info; 20 | int read_only; 21 | int ret; 22 | 23 | if (argc < 2) { 24 | fprintf(stderr, "usage: %s \n", argv[0]); 25 | exit(EXIT_FAILURE); 26 | } 27 | 28 | ret = open(argv[1], O_RDWR); 29 | if (ret < 0) { 30 | perror("open"); 31 | exit(EXIT_FAILURE); 32 | } 33 | printf("file %s opened\n", argv[1]); 34 | fd = ret; 35 | 36 | /* Try reading device info */ 37 | ret = ioctl(fd, CHRDEV_IOC_GETINFO, &info); 38 | if (ret < 0) { 39 | perror("ioctl(CHRDEV_IOC_GETINFO)"); 40 | exit(EXIT_FAILURE); 41 | } 42 | printf("got label=%s and read_only=%d\n", info.label, info.read_only); 43 | 44 | /* Try toggling the device reading mode */ 45 | read_only = !info.read_only; 46 | ret = ioctl(fd, WDIOC_SET_RDONLY, &read_only); 47 | if (ret < 0) { 48 | perror("ioctl(WDIOC_SET_RDONLY)"); 49 | exit(EXIT_FAILURE); 50 | } 51 | printf("device has now read_only=%d\n", read_only); 52 | 53 | close(fd); 54 | 55 | return 0; 56 | } 57 | -------------------------------------------------------------------------------- /Chapter07/chrdev_mmap.c: -------------------------------------------------------------------------------- 1 | /* 2 | * chrdev mmap() testing program 3 | */ 4 | 5 | #include 6 | #include 7 | #include 8 | #include 9 | #include 10 | #include 11 | #include 12 | #include 13 | 14 | int main(int argc, char *argv[]) 15 | { 16 | int fd; 17 | void *addr; 18 | long len; 19 | char *ptr; 20 | int i; 21 | int ret; 22 | 23 | if (argc < 2) { 24 | fprintf(stderr, "usage: %s []\n", argv[0]); 25 | exit(EXIT_FAILURE); 26 | } 27 | len = atol(argv[2]); 28 | 29 | ret = open(argv[1], O_RDWR); 30 | if (ret < 0) { 31 | perror("open"); 32 | exit(EXIT_FAILURE); 33 | } 34 | printf("file %s opened\n", argv[1]); 35 | fd = ret; 36 | 37 | /* Try to remap file into memory */ 38 | addr = mmap(NULL, len, PROT_READ | PROT_WRITE, 39 | MAP_FILE | MAP_SHARED, fd, 0); 40 | if (addr == MAP_FAILED) { 41 | perror("mmap"); 42 | exit(EXIT_FAILURE); 43 | } 44 | printf("got address=%p and len=%ld\n", addr, len); 45 | 46 | /* Do a (partial) dump of the file as it was a buffer of bytes */ 47 | printf("---\n"); 48 | ptr = (char *) addr; 49 | for (i = 0; i < len; i++) 50 | printf("%c", ptr[i]); 51 | 52 | /* Just in case, we modify the first byte by writing char */ 53 | if (argc == 4) { 54 | ptr[0] = argv[3][0]; 55 | printf("---\nFirst character changed to '%c'\n", ptr[0]); 56 | } 57 | 58 | munmap(addr, len); 59 | close(fd); 60 | 61 | return 0; 62 | } 63 | -------------------------------------------------------------------------------- /Chapter07/chrdev_select.c: -------------------------------------------------------------------------------- 1 | /* 2 | * chrdev select() testing program 3 | */ 4 | 5 | #include 6 | #include 7 | #include 8 | #include 9 | #include 10 | #include 11 | #include 12 | #include 13 | 14 | int main(int argc, char *argv[]) 15 | { 16 | int fd; 17 | fd_set read_fds; 18 | char c; 19 | int ret; 20 | 21 | if (argc < 2) { 22 | fprintf(stderr, "usage: %s \n", argv[0]); 23 | exit(EXIT_FAILURE); 24 | } 25 | 26 | ret = open(argv[1], O_RDWR); 27 | if (ret < 0) { 28 | perror("open"); 29 | exit(EXIT_FAILURE); 30 | } 31 | printf("file %s opened\n", argv[1]); 32 | fd = ret; 33 | 34 | while (1) { 35 | /* Set up reading file descriptors */ 36 | FD_ZERO(&read_fds); 37 | FD_SET(STDIN_FILENO, &read_fds); 38 | FD_SET(fd, &read_fds); 39 | 40 | /* Wait for any data fro our device or stdin */ 41 | ret = select(FD_SETSIZE, &read_fds, NULL, NULL, NULL); 42 | if (ret < 0) { 43 | perror("select"); 44 | exit(EXIT_FAILURE); 45 | } 46 | 47 | if (FD_ISSET(STDIN_FILENO, &read_fds)) { 48 | ret = read(STDIN_FILENO, &c, 1); 49 | if (ret < 0) { 50 | perror("read(STDIN, ...)"); 51 | exit(EXIT_FAILURE); 52 | } 53 | printf("got '%c' from stdin!\n", c); 54 | } 55 | if (FD_ISSET(fd, &read_fds)) { 56 | ret = read(fd, &c, 1); 57 | if (ret < 0) { 58 | perror("read(fd, ...)"); 59 | exit(EXIT_FAILURE); 60 | } 61 | printf("got '%c' from device!\n", c); 62 | } 63 | } 64 | 65 | close(fd); 66 | 67 | return 0; 68 | } 69 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | GNU GENERAL PUBLIC LICENSE 2 | Version 2, June 1991 3 | 4 | Copyright (C) 1989, 1991 Free Software Foundation, Inc., 5 | 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 6 | Everyone is permitted to copy and distribute verbatim copies 7 | of this license document, but changing it is not allowed. 8 | 9 | Preamble 10 | 11 | The licenses for most software are designed to take away your 12 | freedom to share and change it. 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You may copy and distribute verbatim copies of the Program's 80 | source code as you receive it, in any medium, provided that you 81 | conspicuously and appropriately publish on each copy an appropriate 82 | copyright notice and disclaimer of warranty; keep intact all the 83 | notices that refer to this License and to the absence of any warranty; 84 | and give any other recipients of the Program a copy of this License 85 | along with the Program. 86 | 87 | You may charge a fee for the physical act of transferring a copy, and 88 | you may at your option offer warranty protection in exchange for a fee. 89 | 90 | 2. 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Many people have made 220 | generous contributions to the wide range of software distributed 221 | through that system in reliance on consistent application of that 222 | system; it is up to the author/donor to decide if he or she is willing 223 | to distribute software through any other system and a licensee cannot 224 | impose that choice. 225 | 226 | This section is intended to make thoroughly clear what is believed to 227 | be a consequence of the rest of this License. 228 | 229 | 8. If the distribution and/or use of the Program is restricted in 230 | certain countries either by patents or by copyrighted interfaces, the 231 | original copyright holder who places the Program under this License 232 | may add an explicit geographical distribution limitation excluding 233 | those countries, so that distribution is permitted only in or among 234 | countries not thus excluded. In such case, this License incorporates 235 | the limitation as if written in the body of this License. 236 | 237 | 9. The Free Software Foundation may publish revised and/or new versions 238 | of the General Public License from time to time. Such new versions will 239 | be similar in spirit to the present version, but may differ in detail to 240 | address new problems or concerns. 241 | 242 | Each version is given a distinguishing version number. If the Program 243 | specifies a version number of this License which applies to it and "any 244 | later version", you have the option of following the terms and conditions 245 | either of that version or of any later version published by the Free 246 | Software Foundation. If the Program does not specify a version number of 247 | this License, you may choose any version ever published by the Free Software 248 | Foundation. 249 | 250 | 10. If you wish to incorporate parts of the Program into other free 251 | programs whose distribution conditions are different, write to the author 252 | to ask for permission. For software which is copyrighted by the Free 253 | Software Foundation, write to the Free Software Foundation; we sometimes 254 | make exceptions for this. Our decision will be guided by the two goals 255 | of preserving the free status of all derivatives of our free software and 256 | of promoting the sharing and reuse of software generally. 257 | 258 | NO WARRANTY 259 | 260 | 11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY 261 | FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN 262 | OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES 263 | PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED 264 | OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 265 | MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS 266 | TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE 267 | PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, 268 | REPAIR OR CORRECTION. 269 | 270 | 12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING 271 | WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR 272 | REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, 273 | INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING 274 | OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED 275 | TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY 276 | YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER 277 | PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE 278 | POSSIBILITY OF SUCH DAMAGES. 279 | 280 | END OF TERMS AND CONDITIONS 281 | 282 | How to Apply These Terms to Your New Programs 283 | 284 | If you develop a new program, and you want it to be of the greatest 285 | possible use to the public, the best way to achieve this is to make it 286 | free software which everyone can redistribute and change under these terms. 287 | 288 | To do so, attach the following notices to the program. It is safest 289 | to attach them to the start of each source file to most effectively 290 | convey the exclusion of warranty; and each file should have at least 291 | the "copyright" line and a pointer to where the full notice is found. 292 | 293 | {description} 294 | Copyright (C) {year} {fullname} 295 | 296 | This program is free software; you can redistribute it and/or modify 297 | it under the terms of the GNU General Public License as published by 298 | the Free Software Foundation; either version 2 of the License, or 299 | (at your option) any later version. 300 | 301 | This program is distributed in the hope that it will be useful, 302 | but WITHOUT ANY WARRANTY; without even the implied warranty of 303 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 304 | GNU General Public License for more details. 305 | 306 | You should have received a copy of the GNU General Public License along 307 | with this program; if not, write to the Free Software Foundation, Inc., 308 | 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. 309 | 310 | Also add information on how to contact you by electronic and paper mail. 311 | 312 | If the program is interactive, make it output a short notice like this 313 | when it starts in an interactive mode: 314 | 315 | Gnomovision version 69, Copyright (C) year name of author 316 | Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'. 317 | This is free software, and you are welcome to redistribute it 318 | under certain conditions; type `show c' for details. 319 | 320 | The hypothetical commands `show w' and `show c' should show the appropriate 321 | parts of the General Public License. Of course, the commands you use may 322 | be called something other than `show w' and `show c'; they could even be 323 | mouse-clicks or menu items--whatever suits your program. 324 | 325 | You should also get your employer (if you work as a programmer) or your 326 | school, if any, to sign a "copyright disclaimer" for the program, if 327 | necessary. Here is a sample; alter the names: 328 | 329 | Yoyodyne, Inc., hereby disclaims all copyright interest in the program 330 | `Gnomovision' (which makes passes at compilers) written by James Hacker. 331 | 332 | {signature of Ty Coon}, 1 April 1989 333 | Ty Coon, President of Vice 334 | 335 | This General Public License does not permit incorporating your program into 336 | proprietary programs. If your program is a subroutine library, you may 337 | consider it more useful to permit linking proprietary applications with the 338 | library. If this is what you want to do, use the GNU Lesser General 339 | Public License instead of this License. 340 | 341 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4 | # Linux Device Driver Development Cookbook 5 | 6 | Linux Device Driver Development Cookbook 7 | 8 | This is the code repository for [Linux Device Driver Development Cookbook](""), published by Packt. 9 | 10 | **Develop custom drivers for your embedded Linux applications** 11 | 12 | ## What is this book about? 13 | Device drivers play a critical role in how the system performs and ensures that the device works in the intended way. 14 | With a recipe based approach this book gives you practical recipes on character drivers and related kernel internals. It shows you how to start writing Linux device drivers and tools to understand, debug or modify them. 15 | 16 | This book covers the following exciting features: 17 | * Become familiar with the latest kernel releases (4.19+/5.x) running on the ESPRESSObin devkit, an ARM 64-bit machine 18 | * Download, configure, modify, and build kernel sources 19 | * Add and remove a device driver or a module from the kernel 20 | * Master kernel programming 21 | * Understand how to implement character drivers to manage different kinds of computer peripheral 22 | * Become well versed with kernel helper functions and objects that can be used to build kernel applications 23 | * Acquire a knowledge of in-depth concepts to manage custom hardware with Linux from both the kernel and user space 24 | 25 | If you feel this book is for you, get your [copy](https://www.amazon.com/dp/1789134323) today! 26 | 27 | https://www.packtpub.com/ 29 | 30 | ## Instructions and Navigations 31 | All of the code is organized into folders. For example, Chapter02. 32 | 33 | The code will look like the following: 34 | ``` 35 | [ 3.421397] mvneta d0030000.ethernet eth0: Using random mac address 3e:a1:6b: 36 | f5:c3:2f 37 | 38 | ``` 39 | 40 | **Following is what you need for this book:** 41 | This book will help anyone who wants to develop their own Linux device drivers for embedded systems. Having basic hand-on with Linux operating system and embedded concepts is necessary. 42 | 43 | With the following software and hardware list you can run all code files present in the book (Chapter 1-9). 44 | ### Software and Hardware List 45 | | Chapter | Software required | OS required | 46 | | -------- | ------------------------------------ | ----------------------------------- | 47 | | 1-7 | Text editor such as vi , emacs, or nano | Ubuntu 18.04.1 LTS Linux, Windows, macOS | 48 | 49 | 50 | We also provide a PDF file that has color images of the screenshots/diagrams used in this book. [Click here to download it](https://www.packtpub.com/sites/default/files/downloads/9781838558802_ColorImages.pdf). 51 | 52 | ### Related products 53 | * Mastering Embedded Linux Programming - Second Edition [[Packt]](https://www.packtpub.com/networking-and-servers/mastering-embedded-linux-programming-second-edition?utm_source=github&utm_medium=repository&utm_campaign=9781787283282) [[Amazon]](https://www.amazon.com/dp/1787283283) 54 | 55 | * Embedded Linux Development Using Yocto Project Cookbook - Second Edition [[Packt]](https://www.packtpub.com/virtualization-and-cloud/embedded-linux-development-using-yocto-project-cookbook-second-edition?utm_source=github&utm_medium=repository&utm_campaign=9781788399210) [[Amazon]](https://www.amazon.com/dp/1788399218) 56 | ## Get to Know the Author 57 | **Rodolfo Giometti** 58 | is an engineer, IT specialist, GNU/Linux expert and software libre evangelist. He is the author of the books BeagleBone Essentials, BeagleBone Home Automation Blueprints and GNU/Linux Rapid Embedded Programming by Packt Publishing and maintainer of the LinuxPPS projects. He still actively contributes to the Linux source code with several patches and new device drivers for industrial applications devices. 59 | 60 | During his 20+ years of experience, he has worked on the x86, ARM, MIPS, and PowerPC-based platforms. 61 | 62 | Now, he is the co-chief at HCE Engineering S.r.l., where he designs new hardware and software systems for the quick prototyping in industry environment, control automation, and remote monitoring. 63 | 64 | 65 | # Other book by the author 66 | * [GNU/Linux Rapid Embedded Programming](https://www.packtpub.com/hardware-and-creative/gnulinux-rapid-embedded-programming?utm_source=github&utm_medium=repository&utm_campaign=9781786461803) 67 | 68 | ### Suggestions and Feedback 69 | [Click here](https://docs.google.com/forms/d/e/1FAIpQLSdy7dATC6QmEL81FIUuymZ0Wy9vH1jHkvpY57OiMeKGqib_Ow/viewform) if you have any feedback or suggestions. 70 | ### Download a free PDF 71 | 72 | If you have already purchased a print or Kindle version of this book, you can get a DRM-free PDF version at no cost.
Simply click on the link to claim your free PDF. 73 |

https://packt.link/free-ebook/9781838558802

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