| 1 | /*
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| 2 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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| 3 | * Copyright (C) 2000, Jan-Derk Bakker (J.D.Bakker@its.tudelft.nl)
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| 4 | * Copyright (C) 2008, BusyBox Team. -solar 4/26/08
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| 5 | */
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| 6 |
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| 7 | //usage:#define devmem_trivial_usage
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| 8 | //usage: "ADDRESS [WIDTH [VALUE]]"
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| 9 | //usage:#define devmem_full_usage "\n\n"
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| 10 | //usage: "Read/write from physical address\n"
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| 11 | //usage: "\n ADDRESS Address to act upon"
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| 12 | //usage: "\n WIDTH Width (8/16/...)"
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| 13 | //usage: "\n VALUE Data to be written"
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| 14 |
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| 15 | #include "libbb.h"
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| 16 |
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| 17 | int devmem_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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| 18 | int devmem_main(int argc UNUSED_PARAM, char **argv)
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| 19 | {
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| 20 | void *map_base, *virt_addr;
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| 21 | uint64_t read_result;
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| 22 | uint64_t writeval = writeval; /* for compiler */
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| 23 | off_t target;
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| 24 | unsigned page_size, mapped_size, offset_in_page;
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| 25 | int fd;
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| 26 | unsigned width = 8 * sizeof(int);
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| 27 |
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| 28 | /* devmem ADDRESS [WIDTH [VALUE]] */
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| 29 | // TODO: options?
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| 30 | // -r: read and output only the value in hex, with 0x prefix
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| 31 | // -w: write only, no reads before or after, and no output
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| 32 | // or make this behavior default?
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| 33 | // Let's try this and see how users react.
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| 34 |
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| 35 | /* ADDRESS */
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| 36 | if (!argv[1])
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| 37 | bb_show_usage();
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| 38 | errno = 0;
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| 39 | target = bb_strtoull(argv[1], NULL, 0); /* allows hex, oct etc */
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| 40 |
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| 41 | /* WIDTH */
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| 42 | if (argv[2]) {
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| 43 | if (isdigit(argv[2][0]) || argv[2][1])
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| 44 | width = xatou(argv[2]);
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| 45 | else {
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| 46 | static const char bhwl[] ALIGN1 = "bhwl";
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| 47 | static const uint8_t sizes[] ALIGN1 = {
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| 48 | 8 * sizeof(char),
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| 49 | 8 * sizeof(short),
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| 50 | 8 * sizeof(int),
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| 51 | 8 * sizeof(long),
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| 52 | 0 /* bad */
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| 53 | };
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| 54 | width = strchrnul(bhwl, (argv[2][0] | 0x20)) - bhwl;
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| 55 | width = sizes[width];
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| 56 | }
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| 57 | /* VALUE */
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| 58 | if (argv[3])
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| 59 | writeval = bb_strtoull(argv[3], NULL, 0);
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| 60 | } else { /* argv[2] == NULL */
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| 61 | /* make argv[3] to be a valid thing to fetch */
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| 62 | argv--;
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| 63 | }
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| 64 | if (errno)
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| 65 | bb_show_usage(); /* one of bb_strtouXX failed */
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| 66 |
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| 67 | fd = xopen("/dev/mem", argv[3] ? (O_RDWR | O_SYNC) : (O_RDONLY | O_SYNC));
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| 68 | mapped_size = page_size = getpagesize();
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| 69 | offset_in_page = (unsigned)target & (page_size - 1);
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| 70 | if (offset_in_page + width > page_size) {
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| 71 | /* This access spans pages.
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| 72 | * Must map two pages to make it possible: */
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| 73 | mapped_size *= 2;
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| 74 | }
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| 75 | map_base = mmap(NULL,
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| 76 | mapped_size,
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| 77 | argv[3] ? (PROT_READ | PROT_WRITE) : PROT_READ,
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| 78 | MAP_SHARED,
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| 79 | fd,
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| 80 | target & ~(off_t)(page_size - 1));
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| 81 | if (map_base == MAP_FAILED)
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| 82 | bb_perror_msg_and_die("mmap");
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| 83 |
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| 84 | // printf("Memory mapped at address %p.\n", map_base);
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| 85 |
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| 86 | virt_addr = (char*)map_base + offset_in_page;
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| 87 |
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| 88 | if (!argv[3]) {
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| 89 | switch (width) {
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| 90 | case 8:
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| 91 | read_result = *(volatile uint8_t*)virt_addr;
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| 92 | break;
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| 93 | case 16:
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| 94 | read_result = *(volatile uint16_t*)virt_addr;
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| 95 | break;
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| 96 | case 32:
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| 97 | read_result = *(volatile uint32_t*)virt_addr;
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| 98 | break;
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| 99 | case 64:
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| 100 | read_result = *(volatile uint64_t*)virt_addr;
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| 101 | break;
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| 102 | default:
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| 103 | bb_error_msg_and_die("bad width");
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| 104 | }
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| 105 | // printf("Value at address 0x%"OFF_FMT"X (%p): 0x%llX\n",
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| 106 | // target, virt_addr,
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| 107 | // (unsigned long long)read_result);
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| 108 | /* Zero-padded output shows the width of access just done */
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| 109 | printf("0x%0*llX\n", (width >> 2), (unsigned long long)read_result);
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| 110 | } else {
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| 111 | switch (width) {
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| 112 | case 8:
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| 113 | *(volatile uint8_t*)virt_addr = writeval;
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| 114 | // read_result = *(volatile uint8_t*)virt_addr;
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| 115 | break;
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| 116 | case 16:
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| 117 | *(volatile uint16_t*)virt_addr = writeval;
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| 118 | // read_result = *(volatile uint16_t*)virt_addr;
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| 119 | break;
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| 120 | case 32:
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| 121 | *(volatile uint32_t*)virt_addr = writeval;
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| 122 | // read_result = *(volatile uint32_t*)virt_addr;
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| 123 | break;
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| 124 | case 64:
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| 125 | *(volatile uint64_t*)virt_addr = writeval;
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| 126 | // read_result = *(volatile uint64_t*)virt_addr;
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| 127 | break;
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| 128 | default:
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| 129 | bb_error_msg_and_die("bad width");
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| 130 | }
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| 131 | // printf("Written 0x%llX; readback 0x%llX\n",
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| 132 | // (unsigned long long)writeval,
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| 133 | // (unsigned long long)read_result);
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| 134 | }
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| 135 |
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| 136 | if (ENABLE_FEATURE_CLEAN_UP) {
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| 137 | if (munmap(map_base, mapped_size) == -1)
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| 138 | bb_perror_msg_and_die("munmap");
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| 139 | close(fd);
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| 140 | }
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| 141 |
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| 142 | return EXIT_SUCCESS;
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| 143 | }
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