diff options
| -rw-r--r-- | miscutils/devmem.c | 79 |
1 files changed, 42 insertions, 37 deletions
diff --git a/miscutils/devmem.c b/miscutils/devmem.c index 8b8edbe7c..4903b5dcb 100644 --- a/miscutils/devmem.c +++ b/miscutils/devmem.c @@ -6,9 +6,6 @@ #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) { @@ -16,10 +13,16 @@ int devmem_main(int argc UNUSED_PARAM, char **argv) uint64_t read_result; uint64_t writeval = writeval; /* for compiler */ off_t target; + unsigned page_size = getpagesize(); int fd; int width = 8 * sizeof(int); /* devmem ADDRESS [WIDTH [VALUE]] */ +// TODO: options? +// -r: read and output only the value in hex, with 0x prefix +// -w: write only, no reads before or after, and no output +// or make this behavior default? +// Let's try this and see how users react. /* ADDRESS */ if (!argv[1]) @@ -54,67 +57,69 @@ int devmem_main(int argc UNUSED_PARAM, char **argv) 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 */, + page_size * 2 /* in case value spans page */, argv[3] ? (PROT_READ | PROT_WRITE) : PROT_READ, MAP_SHARED, fd, - target & ~DEVMEM_MAP_MASK); + target & ~(off_t)(page_size - 1)); 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); + virt_addr = (char*)map_base + (target & (page_size - 1)); - if (argv[3]) { + 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; + 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); + /* Zero-padded output shows the width of access just done */ + printf("0x%0*llX\n", (width >> 2), (unsigned long long)read_result); + } else { + 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; + default: + bb_error_msg_and_die("bad width"); } - printf("Written 0x%llX; readback 0x%llX\n", - (unsigned long long)writeval, - (unsigned long long)read_result); +// 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) + if (munmap(map_base, page_size) == -1) bb_perror_msg_and_die("munmap"); close(fd); } |