diff options
Diffstat (limited to 'miscutils')
| -rw-r--r-- | miscutils/Config.in | 7 | ||||
| -rw-r--r-- | miscutils/Kbuild | 1 | ||||
| -rw-r--r-- | miscutils/devmem.c | 123 |
3 files changed, 131 insertions, 0 deletions
diff --git a/miscutils/Config.in b/miscutils/Config.in index 074e6c4..f8b4575 100644 --- a/miscutils/Config.in +++ b/miscutils/Config.in @@ -196,6 +196,13 @@ config FEATURE_DEVFS /dev/loop0. If your /dev directory has normal names instead of devfs names, you don't want this. +config DEVMEM + bool "devmem" + default n + help + devmem is a small program that reads and writes from physical + memory using /dev/mem. + config EJECT bool "eject" default n diff --git a/miscutils/Kbuild b/miscutils/Kbuild index c12b12d..13791ef 100644 --- a/miscutils/Kbuild +++ b/miscutils/Kbuild @@ -13,6 +13,7 @@ lib-$(CONFIG_CROND) += crond.o lib-$(CONFIG_CRONTAB) += crontab.o lib-$(CONFIG_DC) += dc.o lib-$(CONFIG_DEVFSD) += devfsd.o +lib-$(CONFIG_DEVMEM) += devmem.o lib-$(CONFIG_EJECT) += eject.o lib-$(CONFIG_FBSPLASH) += fbsplash.o lib-$(CONFIG_HDPARM) += hdparm.o diff --git a/miscutils/devmem.c b/miscutils/devmem.c new file mode 100644 index 0000000..8b8edbe --- /dev/null +++ b/miscutils/devmem.c @@ -0,0 +1,123 @@ +/* + * Licensed under the GPL v2 or later, see the file LICENSE in this tarball. + * Copyright (C) 2000, Jan-Derk Bakker (J.D.Bakker@its.tudelft.nl) + * Copyright (C) 2008, BusyBox Team. -solar 4/26/08 + */ + +#include "libbb.h" + +#define DEVMEM_MAP_SIZE 4096 +#define DEVMEM_MAP_MASK (off_t)(DEVMEM_MAP_SIZE - 1) + +int devmem_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; +int devmem_main(int argc UNUSED_PARAM, char **argv) +{ + void *map_base, *virt_addr; + uint64_t read_result; + uint64_t writeval = writeval; /* for compiler */ + off_t target; + int fd; + int width = 8 * sizeof(int); + + /* devmem ADDRESS [WIDTH [VALUE]] */ + + /* ADDRESS */ + if (!argv[1]) + bb_show_usage(); + errno = 0; + target = bb_strtoull(argv[1], NULL, 0); /* allows hex, oct etc */ + + /* WIDTH */ + if (argv[2]) { + if (isdigit(argv[2][0]) || argv[2][1]) + width = xatou(argv[2]); + else { + static const char bhwl[] ALIGN1 = "bhwl"; + static const uint8_t sizes[] ALIGN1 = { + 8 * sizeof(char), + 8 * sizeof(short), + 8 * sizeof(int), + 8 * sizeof(long), + 0 /* bad */ + }; + width = strchrnul(bhwl, (argv[2][0] | 0x20)) - bhwl; + width = sizes[width]; + } + /* VALUE */ + if (argv[3]) + writeval = bb_strtoull(argv[3], NULL, 0); + } else { /* argv[2] == NULL */ + /* make argv[3] to be a valid thing to use */ + argv--; + } + if (errno) + bb_show_usage(); /* bb_strtouXX failed */ + + fd = xopen("/dev/mem", argv[3] ? (O_RDWR | O_SYNC) : (O_RDONLY | O_SYNC)); + + map_base = mmap(NULL, + DEVMEM_MAP_SIZE * 2 /* in case value spans page */, + argv[3] ? (PROT_READ | PROT_WRITE) : PROT_READ, + MAP_SHARED, + fd, + target & ~DEVMEM_MAP_MASK); + if (map_base == MAP_FAILED) + bb_perror_msg_and_die("mmap"); + +// printf("Memory mapped at address %p.\n", map_base); + + virt_addr = (char*)map_base + (target & DEVMEM_MAP_MASK); + + switch (width) { + case 8: + read_result = *(volatile uint8_t*)virt_addr; + break; + case 16: + read_result = *(volatile uint16_t*)virt_addr; + break; + case 32: + read_result = *(volatile uint32_t*)virt_addr; + break; + case 64: + read_result = *(volatile uint64_t*)virt_addr; + break; + default: + bb_error_msg_and_die("bad width"); + } + + printf("Value at address 0x%"OFF_FMT"X (%p): 0x%llX\n", + target, virt_addr, + (unsigned long long)read_result); + + if (argv[3]) { + switch (width) { + case 8: + *(volatile uint8_t*)virt_addr = writeval; + read_result = *(volatile uint8_t*)virt_addr; + break; + case 16: + *(volatile uint16_t*)virt_addr = writeval; + read_result = *(volatile uint16_t*)virt_addr; + break; + case 32: + *(volatile uint32_t*)virt_addr = writeval; + read_result = *(volatile uint32_t*)virt_addr; + break; + case 64: + *(volatile uint64_t*)virt_addr = writeval; + read_result = *(volatile uint64_t*)virt_addr; + break; + } + printf("Written 0x%llX; readback 0x%llX\n", + (unsigned long long)writeval, + (unsigned long long)read_result); + } + + if (ENABLE_FEATURE_CLEAN_UP) { + if (munmap(map_base, DEVMEM_MAP_SIZE) == -1) + bb_perror_msg_and_die("munmap"); + close(fd); + } + + return EXIT_SUCCESS; +} |