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129 lines
3.3 KiB
C
129 lines
3.3 KiB
C
/*
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* Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
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* Copyright (C) 2000, Jan-Derk Bakker (J.D.Bakker@its.tudelft.nl)
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* Copyright (C) 2008, BusyBox Team. -solar 4/26/08
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*/
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#include "libbb.h"
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int devmem_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int devmem_main(int argc UNUSED_PARAM, char **argv)
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{
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void *map_base, *virt_addr;
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uint64_t read_result;
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uint64_t writeval = writeval; /* for compiler */
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off_t target;
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unsigned page_size = getpagesize();
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int fd;
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int width = 8 * sizeof(int);
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/* devmem ADDRESS [WIDTH [VALUE]] */
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// TODO: options?
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// -r: read and output only the value in hex, with 0x prefix
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// -w: write only, no reads before or after, and no output
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// or make this behavior default?
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// Let's try this and see how users react.
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/* ADDRESS */
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if (!argv[1])
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bb_show_usage();
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errno = 0;
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target = bb_strtoull(argv[1], NULL, 0); /* allows hex, oct etc */
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/* WIDTH */
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if (argv[2]) {
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if (isdigit(argv[2][0]) || argv[2][1])
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width = xatou(argv[2]);
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else {
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static const char bhwl[] ALIGN1 = "bhwl";
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static const uint8_t sizes[] ALIGN1 = {
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8 * sizeof(char),
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8 * sizeof(short),
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8 * sizeof(int),
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8 * sizeof(long),
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0 /* bad */
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};
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width = strchrnul(bhwl, (argv[2][0] | 0x20)) - bhwl;
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width = sizes[width];
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}
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/* VALUE */
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if (argv[3])
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writeval = bb_strtoull(argv[3], NULL, 0);
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} else { /* argv[2] == NULL */
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/* make argv[3] to be a valid thing to use */
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argv--;
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}
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if (errno)
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bb_show_usage(); /* bb_strtouXX failed */
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fd = xopen("/dev/mem", argv[3] ? (O_RDWR | O_SYNC) : (O_RDONLY | O_SYNC));
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map_base = mmap(NULL,
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page_size * 2 /* in case value spans page */,
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argv[3] ? (PROT_READ | PROT_WRITE) : PROT_READ,
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MAP_SHARED,
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fd,
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target & ~(off_t)(page_size - 1));
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if (map_base == MAP_FAILED)
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bb_perror_msg_and_die("mmap");
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// printf("Memory mapped at address %p.\n", map_base);
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virt_addr = (char*)map_base + (target & (page_size - 1));
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if (!argv[3]) {
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switch (width) {
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case 8:
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read_result = *(volatile uint8_t*)virt_addr;
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break;
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case 16:
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read_result = *(volatile uint16_t*)virt_addr;
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break;
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case 32:
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read_result = *(volatile uint32_t*)virt_addr;
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break;
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case 64:
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read_result = *(volatile uint64_t*)virt_addr;
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break;
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default:
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bb_error_msg_and_die("bad width");
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}
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// printf("Value at address 0x%"OFF_FMT"X (%p): 0x%llX\n",
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// target, virt_addr,
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// (unsigned long long)read_result);
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/* Zero-padded output shows the width of access just done */
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printf("0x%0*llX\n", (width >> 2), (unsigned long long)read_result);
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} else {
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switch (width) {
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case 8:
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*(volatile uint8_t*)virt_addr = writeval;
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// read_result = *(volatile uint8_t*)virt_addr;
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break;
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case 16:
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*(volatile uint16_t*)virt_addr = writeval;
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// read_result = *(volatile uint16_t*)virt_addr;
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break;
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case 32:
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*(volatile uint32_t*)virt_addr = writeval;
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// read_result = *(volatile uint32_t*)virt_addr;
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break;
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case 64:
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*(volatile uint64_t*)virt_addr = writeval;
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// read_result = *(volatile uint64_t*)virt_addr;
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break;
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default:
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bb_error_msg_and_die("bad width");
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}
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// printf("Written 0x%llX; readback 0x%llX\n",
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// (unsigned long long)writeval,
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// (unsigned long long)read_result);
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}
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if (ENABLE_FEATURE_CLEAN_UP) {
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if (munmap(map_base, page_size * 2) == -1)
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bb_perror_msg_and_die("munmap");
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close(fd);
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}
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return EXIT_SUCCESS;
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}
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