├── .gitignore ├── LICENSE.txt ├── Makefile ├── README └── pcimem.c /.gitignore: -------------------------------------------------------------------------------- 1 | # General cruft that we don't want to commit 2 | *~ 3 | *.o 4 | pcimem 5 | -------------------------------------------------------------------------------- /LICENSE.txt: -------------------------------------------------------------------------------- 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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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 | 294 | Copyright (C) 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 | , 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 | -------------------------------------------------------------------------------- /Makefile: -------------------------------------------------------------------------------- 1 | 2 | CC ?= gcc 3 | CFLAGS ?= -Wall -g 4 | 5 | main: pcimem 6 | 7 | clean: 8 | -rm -f *.o *~ core pcimem 9 | 10 | -------------------------------------------------------------------------------- /README: -------------------------------------------------------------------------------- 1 | == Overview == 2 | 3 | The pcimem application provides a simple method of reading and writing 4 | to memory registers on a PCI card. 5 | 6 | Usage: ./pcimem { sys file } { offset } [ type [ data ] ] 7 | sys file: sysfs file for the pci resource to act on 8 | offset : offset into pci memory region to act upon 9 | type : access operation type : [b]yte, [h]alfword, [w]ord, [d]ouble-word 10 | data : data to be written 11 | 12 | == Platform Support == 13 | 14 | WARNING !! This method is platform dependent and may not work on your 15 | particular target architecture. Refer to the PowerPC section below. 16 | 17 | == Example == 18 | 19 | bash# ./pcimem /sys/devices/pci0001\:00/0001\:00\:07.0/resource0 0 w 20 | /sys/devices/pci0001:00/0001:00:07.0/resource0 opened. 21 | Target offset is 0x0, page size is 4096 22 | mmap(0, 4096, 0x3, 0x1, 3, 0x0) 23 | PCI Memory mapped to address 0x4801f000. 24 | Value at offset 0x0 (0x4801f000): 0xC0BE0100 25 | 26 | 27 | == Why do this at all ? == 28 | 29 | When I start working on a new PCI device driver I generally go through a 30 | discovery phase of reading and writing to certain registers on the PCI card. 31 | Over the years I have written lots of small kernel modules to probe addresses 32 | within the PCI memory space, constantly iterating: modify code, recompile, scp 33 | to target, load module, unload module, dmesg. 34 | 35 | Urk! There has to be a better way - sysfs and mmap() to the rescue. 36 | 37 | 38 | == Sysfs == 39 | 40 | Let's start at with the PCI files under sysfs: 41 | 42 | bash# ls -l /sys/devices/pci0001\:00/0001\:00\:07.0/ 43 | total 0 44 | -rw-r--r-- 1 root root     4096 Jul  2 20:13 broken_parity_status 45 | lrwxrwxrwx 1 root root        0 Jul  2 20:13 bus -> ../../../bus/pci 46 | -r--r--r-- 1 root root     4096 Jul  2 20:13 class 47 | -rw-r--r-- 1 root root      256 Jul  2 20:13 config 48 | -r--r--r-- 1 root root     4096 Jul  2 20:13 device 49 | -r--r--r-- 1 root root     4096 Jul  2 20:13 devspec 50 | -rw------- 1 root root     4096 Jul  2 20:13 enable 51 | -r--r--r-- 1 root root     4096 Jul  2 20:13 irq 52 | -r--r--r-- 1 root root     4096 Jul  2 20:13 local_cpus 53 | -r--r--r-- 1 root root     4096 Jul  2 20:13 modalias 54 | -rw-r--r-- 1 root root     4096 Jul  2 20:13 msi_bus 55 | -r--r--r-- 1 root root     4096 Jul  2 20:13 resource 56 | -rw------- 1 root root     4096 Jul  2 20:13 resource0 57 | -rw------- 1 root root    65536 Jul  2 20:13 resource1 58 | -rw------- 1 root root 16777216 Jul  2 20:13 resource2 59 | lrwxrwxrwx 1 root root        0 Jul  2 20:13 subsystem -> ../../../bus/pci 60 | -r--r--r-- 1 root root     4096 Jul  2 20:13 subsystem_device 61 | -r--r--r-- 1 root root     4096 Jul  2 20:13 subsystem_vendor 62 | -rw-r--r-- 1 root root     4096 Jul  2 20:13 uevent 63 | -r--r--r-- 1 root root     4096 Jul  2 20:13 vendor 64 | 65 | The vendor and device files report the PCI vendor ID and device ID: 66 | 67 | bash# cat device 68 | 0x0001 69 | 70 | This info is also available from lspci 71 | 72 | bash# lspci -v 73 | 0001:00:07.0 Class 0680: Unknown device bec0:0001 (rev 01) 74 |     Flags: bus master, 66MHz, medium devsel, latency 128, IRQ 31 75 |     Memory at 8d010000 (32-bit, non-prefetchable) [size=4K] 76 |     Memory at 8d000000 (32-bit, non-prefetchable) [size=64K] 77 |     Memory at 8c000000 (32-bit, non-prefetchable) [size=16M] 78 | 79 | This PCI card makes 3 seperate regions of memory available to the host 80 | computer. The sysfs resource0 file corresponds to the first memory region. The 81 | PCI card lets the host computer know about these memory regions using the BAR 82 | registers in the PCI config. 83 | 84 | == mmap() == 85 | 86 | These sysfs resource can be used with mmap() to map the PCI memory into a 87 | userspace applications memory space.  The application then has a pointer to the 88 | start of the PCI memory region and can read and write values directly. (There 89 | is a bit more going on here with respect to memory pointers, but that is all 90 | taken care of by the kernel). 91 | 92 | fd = open("/sys/devices/pci0001\:00/0001\:00\:07.0/resource0", O_RDWR | O_SYNC); 93 | ptr = mmap(0, 4096, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); 94 | printf("PCI BAR0 0x0000 = 0x%4x\n",  *((unsigned short *) ptr); 95 | 96 | == PowerPC == 97 | 98 | To make this work on a PowerPC architecture you also need to make a small 99 | change to the pci core. My example is from kernel 2.6.34, and hopefully this 100 | will be fixed for us in a later kernel version. 101 | 102 | bash# vi arch/powerpc/kernel/pci-common.c 103 |     /* If memory, add on the PCI bridge address offset */ 104 |      if (mmap_state == pci_mmap_mem) { 105 | -#if 0 /* See comment in pci_resource_to_user() for why this is disabled */ 106 | +#if 1 /* See comment in pci_resource_to_user() for why this is disabled */ 107 |          *offset += hose->pci_mem_offset; 108 |  #endif 109 |          res_bit = IORESOURCE_MEM; 110 |   111 |          /* We pass a fully fixed up address to userland for MMIO instead of 112 |          * a BAR value because X is lame and expects to be able to use that 113 |          * to pass to /dev/mem ! 114 |          * 115 |          * That means that we'll have potentially 64 bits values where some 116 |          * userland apps only expect 32 (like X itself since it thinks only 117 |          * Sparc has 64 bits MMIO) but if we don't do that, we break it on 118 |          * 32 bits CHRPs :-( 119 |          * 120 |          * Hopefully, the sysfs insterface is immune to that gunk. Once X 121 |          * has been fixed (and the fix spread enough), we can re-enable the 122 |          * 2 lines below and pass down a BAR value to userland. In that case 123 |          * we'll also have to re-enable the matching code in 124 |          * __pci_mmap_make_offset(). 125 |          * 126 |          * BenH. 127 |          */ 128 | -#if 0 129 | +#if 1 130 |         else if (rsrc->flags & IORESOURCE_MEM) 131 |                 offset = hose->pci_mem_offset; 132 | #endif 133 | 134 | -------------------------------------------------------------------------------- /pcimem.c: -------------------------------------------------------------------------------- 1 | /* 2 | * pcimem.c: Simple program to read/write from/to a pci device from userspace. 3 | * 4 | * Copyright (C) 2010, Bill Farrow (bfarrow@beyondelectronics.us) 5 | * 6 | * Based on the devmem2.c code 7 | * Copyright (C) 2000, Jan-Derk Bakker (J.D.Bakker@its.tudelft.nl) 8 | * 9 | * This program is free software; you can redistribute it and/or modify 10 | * it under the terms of the GNU General Public License as published by 11 | * the Free Software Foundation; either version 2 of the License, or 12 | * (at your option) any later version. 13 | * 14 | * This program is distributed in the hope that it will be useful, 15 | * but WITHOUT ANY WARRANTY; without even the implied warranty of 16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 17 | * GNU General Public License for more details. 18 | * 19 | * You should have received a copy of the GNU General Public License 20 | * along with this program; if not, write to the Free Software 21 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 22 | * 23 | */ 24 | 25 | #include 26 | #include 27 | #include 28 | #include 29 | #include 30 | #include 31 | #include 32 | #include 33 | #include 34 | #include 35 | #include 36 | #include 37 | 38 | #define PRINT_ERROR \ 39 | do { \ 40 | fprintf(stderr, "Error at line %d, file %s (%d) [%s]\n", \ 41 | __LINE__, __FILE__, errno, strerror(errno)); exit(1); \ 42 | } while(0) 43 | 44 | 45 | int main(int argc, char **argv) { 46 | int fd; 47 | void *map_base, *virt_addr; 48 | uint64_t read_result, writeval, prev_read_result = 0; 49 | char *filename; 50 | off_t target, target_base; 51 | int access_type = 'w'; 52 | int items_count = 1; 53 | int verbose = 0; 54 | int read_result_dupped = 0; 55 | int type_width; 56 | int i; 57 | int map_size = 4096UL; 58 | 59 | if(argc < 3) { 60 | // pcimem /sys/bus/pci/devices/0001\:00\:07.0/resource0 0x100 w 0x00 61 | // argv[0] [1] [2] [3] [4] 62 | fprintf(stderr, "\nUsage:\t%s { sysfile } { offset } [ type*count [ data ] ]\n" 63 | "\tsys file: sysfs file for the pci resource to act on\n" 64 | "\toffset : offset into pci memory region to act upon\n" 65 | "\ttype : access operation type : [b]yte, [h]alfword, [w]ord, [d]ouble-word\n" 66 | "\t*count : number of items to read: w*100 will dump 100 words\n" 67 | "\tdata : data to be written\n\n", 68 | argv[0]); 69 | exit(1); 70 | } 71 | filename = argv[1]; 72 | target = strtoul(argv[2], 0, 0); 73 | 74 | if(argc > 3) { 75 | access_type = tolower(argv[3][0]); 76 | if (argv[3][1] == '*') 77 | items_count = strtoul(argv[3]+2, 0, 0); 78 | } 79 | 80 | switch(access_type) { 81 | case 'b': 82 | type_width = 1; 83 | break; 84 | case 'h': 85 | type_width = 2; 86 | break; 87 | case 'w': 88 | type_width = 4; 89 | break; 90 | case 'd': 91 | type_width = 8; 92 | break; 93 | default: 94 | fprintf(stderr, "Illegal data type '%c'.\n", access_type); 95 | exit(2); 96 | } 97 | 98 | if((fd = open(filename, O_RDWR | O_SYNC)) == -1) PRINT_ERROR; 99 | printf("%s opened.\n", filename); 100 | printf("Target offset is 0x%x, page size is %ld\n", (int) target, sysconf(_SC_PAGE_SIZE)); 101 | fflush(stdout); 102 | 103 | target_base = target & ~(sysconf(_SC_PAGE_SIZE)-1); 104 | if (target + items_count*type_width - target_base > map_size) 105 | map_size = target + items_count*type_width - target_base; 106 | 107 | /* Map one page */ 108 | printf("mmap(%d, %d, 0x%x, 0x%x, %d, 0x%x)\n", 0, map_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, (int) target); 109 | 110 | map_base = mmap(0, map_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, target_base); 111 | if(map_base == (void *) -1) PRINT_ERROR; 112 | printf("PCI Memory mapped to address 0x%08lx.\n", (unsigned long) map_base); 113 | fflush(stdout); 114 | 115 | for (i = 0; i < items_count; i++) { 116 | 117 | virt_addr = map_base + target + i*type_width - target_base; 118 | switch(access_type) { 119 | case 'b': 120 | read_result = *((uint8_t *) virt_addr); 121 | break; 122 | case 'h': 123 | read_result = *((uint16_t *) virt_addr); 124 | break; 125 | case 'w': 126 | read_result = *((uint32_t *) virt_addr); 127 | break; 128 | case 'd': 129 | read_result = *((uint64_t *) virt_addr); 130 | break; 131 | } 132 | 133 | if (verbose) 134 | printf("Value at offset 0x%X (%p): 0x%0*lX\n", (int) target + i*type_width, virt_addr, type_width*2, read_result); 135 | else { 136 | if (read_result != prev_read_result || i == 0) { 137 | printf("0x%04X: 0x%0*lX\n", (int)(target + i*type_width), type_width*2, read_result); 138 | read_result_dupped = 0; 139 | } else { 140 | if (!read_result_dupped) 141 | printf("...\n"); 142 | read_result_dupped = 1; 143 | } 144 | } 145 | 146 | prev_read_result = read_result; 147 | 148 | } 149 | 150 | fflush(stdout); 151 | 152 | if(argc > 4) { 153 | writeval = strtoull(argv[4], NULL, 0); 154 | switch(access_type) { 155 | case 'b': 156 | *((uint8_t *) virt_addr) = writeval; 157 | read_result = *((uint8_t *) virt_addr); 158 | break; 159 | case 'h': 160 | *((uint16_t *) virt_addr) = writeval; 161 | read_result = *((uint16_t *) virt_addr); 162 | break; 163 | case 'w': 164 | *((uint32_t *) virt_addr) = writeval; 165 | read_result = *((uint32_t *) virt_addr); 166 | break; 167 | case 'd': 168 | *((uint64_t *) virt_addr) = writeval; 169 | read_result = *((uint64_t *) virt_addr); 170 | break; 171 | } 172 | printf("Written 0x%0*lX; readback 0x%*lX\n", type_width, 173 | writeval, type_width, read_result); 174 | fflush(stdout); 175 | } 176 | 177 | if(munmap(map_base, map_size) == -1) PRINT_ERROR; 178 | close(fd); 179 | return 0; 180 | } 181 | --------------------------------------------------------------------------------