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devmem: make it more script-friendly; don't do any reads

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and output nothing if writing was requested. -100 bytes
This commit is contained in:
Denis Vlasenko 2008-10-26 17:26:55 +00:00
parent e1ef89abad
commit 043246560f
1 changed files with 42 additions and 37 deletions
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79
miscutils/devmem.c
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@ -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);
virt_addr = (char*)map_base + (target & (page_size - 1));
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]) {
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("Written 0x%llX; readback 0x%llX\n",
(unsigned long long)writeval,
(unsigned long long)read_result);
// 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);
}
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);
}