├── deps.sh
├── .gitignore
├── user-mode-program
    ├── blink-led
    └── blink-led.c
├── Makefile
└── lll-gpio-driver.c


/deps.sh:
--------------------------------------------------------------------------------
1 | #!/bin/sh
2 | 
3 | sudo apt-get install gcc raspberrypi-kernel-headers
4 | 


--------------------------------------------------------------------------------
/.gitignore:
--------------------------------------------------------------------------------
1 | .*.cmd
2 | *.o
3 | *.ko
4 | *.mod
5 | *.mod.c
6 | *.order
7 | Module.symvers
8 | 


--------------------------------------------------------------------------------
/user-mode-program/blink-led:
--------------------------------------------------------------------------------
https://raw.githubusercontent.com/lowleveltv/lll-gpio-driver/HEAD/user-mode-program/blink-led


--------------------------------------------------------------------------------
/Makefile:
--------------------------------------------------------------------------------
 1 | obj-m += lll-gpio-driver.o
 2 | 
 3 | KDIR = /lib/modules/$(shell uname -r)/build
 4 | 
 5 | all:
 6 | 	make -C $(KDIR) M=$(shell pwd) modules
 7 | 
 8 | clean:
 9 | 	make -C $(KDIR) M=$(shell pwd) clean
10 | 


--------------------------------------------------------------------------------
/user-mode-program/blink-led.c:
--------------------------------------------------------------------------------
 1 | #include <stdio.h>
 2 | #include <sys/types.h>
 3 | #include <sys/stat.h>
 4 | #include <fcntl.h>
 5 | #include <unistd.h>
 6 | 
 7 | int main ()
 8 | {
 9 | 	int f = open("/proc/lll-gpio", O_RDWR);
10 | 
11 | 	while (1)
12 | 	{
13 | 		write(f, "21,1", 4);
14 | 		usleep(500000);
15 | 		write(f, "21,0", 4);
16 | 		usleep(500000);
17 | 	}
18 | }
19 | 


--------------------------------------------------------------------------------
/lll-gpio-driver.c:
--------------------------------------------------------------------------------
  1 | #include <linux/kernel.h>
  2 | #include <linux/init.h>
  3 | #include <linux/module.h>
  4 | 
  5 | #include <linux/proc_fs.h>
  6 | #include <linux/slab.h>
  7 | 
  8 | #include <asm/io.h>
  9 | 
 10 | #define LLL_MAX_USER_SIZE 1024
 11 | 
 12 | #define BCM2837_GPIO_ADDRESS 0x3F200000
 13 | #define BCM2711_GPIO_ADDRESS 0xfe200000
 14 | 
 15 | static struct proc_dir_entry *lll_proc = NULL;
 16 | 
 17 | static char data_buffer[LLL_MAX_USER_SIZE+1] = {0};
 18 | 
 19 | static unsigned int *gpio_registers = NULL;
 20 | 
 21 | static void gpio_pin_on(unsigned int pin)
 22 | {
 23 | 	unsigned int fsel_index = pin/10;
 24 | 	unsigned int fsel_bitpos = pin%10;
 25 | 	unsigned int* gpio_fsel = gpio_registers + fsel_index;
 26 | 	unsigned int* gpio_on_register = (unsigned int*)((char*)gpio_registers + 0x1c);
 27 | 
 28 | 	*gpio_fsel &= ~(7 << (fsel_bitpos*3));
 29 | 	*gpio_fsel |= (1 << (fsel_bitpos*3));
 30 | 	*gpio_on_register |= (1 << pin);
 31 | 
 32 | 	return;
 33 | }
 34 | 
 35 | static void gpio_pin_off(unsigned int pin)
 36 | {
 37 | 	unsigned int *gpio_off_register = (unsigned int*)((char*)gpio_registers + 0x28);
 38 | 	*gpio_off_register |= (1<<pin);
 39 | 	return;
 40 | }
 41 | 
 42 | ssize_t lll_read(struct file *file, char __user *user, size_t size, loff_t *off)
 43 | {
 44 | 	return copy_to_user(user,"Hello!\n", 7) ? 0 : 7;
 45 | }
 46 | 
 47 | ssize_t lll_write(struct file *file, const char __user *user, size_t size, loff_t *off)
 48 | {
 49 | 	unsigned int pin = UINT_MAX;
 50 | 	unsigned int value = UINT_MAX;
 51 | 
 52 | 	memset(data_buffer, 0x0, sizeof(data_buffer));
 53 | 
 54 | 	if (size > LLL_MAX_USER_SIZE)
 55 | 	{
 56 | 		size = LLL_MAX_USER_SIZE;
 57 | 	}
 58 | 
 59 | 	if (copy_from_user(data_buffer, user, size))
 60 | 		return 0;
 61 | 
 62 | 	printk("Data buffer: %s\n", data_buffer);
 63 | 
 64 | 	if (sscanf(data_buffer, "%d,%d", &pin, &value) != 2)
 65 | 	{
 66 | 		printk("Inproper data format submitted\n");
 67 | 		return size;
 68 | 	}
 69 | 
 70 | 	if (pin > 21 || pin < 0)
 71 | 	{
 72 | 		printk("Invalid pin number submitted\n");
 73 | 		return size;
 74 | 	}
 75 | 
 76 | 	if (value != 0 && value != 1)
 77 | 	{
 78 | 		printk("Invalid on/off value\n");
 79 | 		return size;
 80 | 	}
 81 | 
 82 | 	printk("You said pin %d, value %d\n", pin, value);
 83 | 	if (value == 1)
 84 | 	{
 85 | 		gpio_pin_on(pin);
 86 | 	} else if (value == 0)
 87 | 	{
 88 | 		gpio_pin_off(pin);
 89 | 	}
 90 | 
 91 | 	return size;
 92 | }
 93 | 
 94 | static const struct proc_ops lll_proc_fops = 
 95 | {
 96 | 	.proc_read = lll_read,
 97 | 	.proc_write = lll_write,
 98 | };
 99 | 
100 | 
101 | static int __init gpio_driver_init(void)
102 | {
103 | 	printk("Welcome to my driver!\n");
104 | 	
105 | 	gpio_registers = (int*)ioremap(BCM2837_GPIO_ADDRESS, PAGE_SIZE);
106 | 	if (gpio_registers == NULL)
107 | 	{
108 | 		printk("Failed to map GPIO memory to driver\n");
109 | 		return -1;
110 | 	}
111 | 	
112 | 	printk("Successfully mapped in GPIO memory\n");
113 | 	
114 | 	// create an entry in the proc-fs
115 | 	lll_proc = proc_create("lll-gpio", 0666, NULL, &lll_proc_fops);
116 | 	if (lll_proc == NULL)
117 | 	{
118 | 		return -1;
119 | 	}
120 | 
121 | 	return 0;
122 | }
123 | 
124 | static void __exit gpio_driver_exit(void)
125 | {
126 | 	printk("Leaving my driver!\n");
127 | 	iounmap(gpio_registers);
128 | 	proc_remove(lll_proc);
129 | 	return;
130 | }
131 | 
132 | module_init(gpio_driver_init);
133 | module_exit(gpio_driver_exit);
134 | 
135 | MODULE_LICENSE("GPL");
136 | MODULE_AUTHOR("Low Level Learning");
137 | MODULE_DESCRIPTION("Test of writing drivers for RASPI");
138 | MODULE_VERSION("1.0");
139 | 


--------------------------------------------------------------------------------