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    Contents of /tags/mkinitrd-6_1_3/busybox/miscutils/devmem.c

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    Revision 846 - (show annotations) (download)
    Mon May 4 18:51:23 2009 UTC (15 years, 1 month ago) by niro
    File MIME type: text/plain
    File size: 3429 byte(s) 
    tagged 'mkinitrd-6_1_3'
    1 /*
    2 * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
    3 * Copyright (C) 2000, Jan-Derk Bakker (J.D.Bakker@its.tudelft.nl)
    4 * Copyright (C) 2008, BusyBox Team. -solar 4/26/08
    5 */
    6
    7 #include "libbb.h"
    8
    9 int devmem_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
    10 int devmem_main(int argc UNUSED_PARAM, char **argv)
    11 {
    12 void *map_base, *virt_addr;
    13 uint64_t read_result;
    14 uint64_t writeval = writeval; /* for compiler */
    15 off_t target;
    16 unsigned page_size = getpagesize();
    17 int fd;
    18 int width = 8 * sizeof(int);
    19
    20 /* devmem ADDRESS [WIDTH [VALUE]] */
    21 // TODO: options?
    22 // -r: read and output only the value in hex, with 0x prefix
    23 // -w: write only, no reads before or after, and no output
    24 // or make this behavior default?
    25 // Let's try this and see how users react.
    26
    27 /* ADDRESS */
    28 if (!argv[1])
    29 bb_show_usage();
    30 errno = 0;
    31 target = bb_strtoull(argv[1], NULL, 0); /* allows hex, oct etc */
    32
    33 /* WIDTH */
    34 if (argv[2]) {
    35 if (isdigit(argv[2][0]) || argv[2][1])
    36 width = xatou(argv[2]);
    37 else {
    38 static const char bhwl[] ALIGN1 = "bhwl";
    39 static const uint8_t sizes[] ALIGN1 = {
    40 8 * sizeof(char),
    41 8 * sizeof(short),
    42 8 * sizeof(int),
    43 8 * sizeof(long),
    44 0 /* bad */
    45 };
    46 width = strchrnul(bhwl, (argv[2][0] | 0x20)) - bhwl;
    47 width = sizes[width];
    48 }
    49 /* VALUE */
    50 if (argv[3])
    51 writeval = bb_strtoull(argv[3], NULL, 0);
    52 } else { /* argv[2] == NULL */
    53 /* make argv[3] to be a valid thing to use */
    54 argv--;
    55 }
    56 if (errno)
    57 bb_show_usage(); /* bb_strtouXX failed */
    58
    59 fd = xopen("/dev/mem", argv[3] ? (O_RDWR | O_SYNC) : (O_RDONLY | O_SYNC));
    60 map_base = mmap(NULL,
    61 page_size * 2 /* in case value spans page */,
    62 argv[3] ? (PROT_READ | PROT_WRITE) : PROT_READ,
    63 MAP_SHARED,
    64 fd,
    65 target & ~(off_t)(page_size - 1));
    66 if (map_base == MAP_FAILED)
    67 bb_perror_msg_and_die("mmap");
    68
    69 // printf("Memory mapped at address %p.\n", map_base);
    70
    71 virt_addr = (char*)map_base + (target & (page_size - 1));
    72
    73 if (!argv[3]) {
    74 switch (width) {
    75 case 8:
    76 read_result = *(volatile uint8_t*)virt_addr;
    77 break;
    78 case 16:
    79 read_result = *(volatile uint16_t*)virt_addr;
    80 break;
    81 case 32:
    82 read_result = *(volatile uint32_t*)virt_addr;
    83 break;
    84 case 64:
    85 read_result = *(volatile uint64_t*)virt_addr;
    86 break;
    87 default:
    88 bb_error_msg_and_die("bad width");
    89 }
    90 // printf("Value at address 0x%"OFF_FMT"X (%p): 0x%llX\n",
    91 // target, virt_addr,
    92 // (unsigned long long)read_result);
    93 /* Zero-padded output shows the width of access just done */
    94 printf("0x%0*llX\n", (width >> 2), (unsigned long long)read_result);
    95 } else {
    96 switch (width) {
    97 case 8:
    98 *(volatile uint8_t*)virt_addr = writeval;
    99 // read_result = *(volatile uint8_t*)virt_addr;
    100 break;
    101 case 16:
    102 *(volatile uint16_t*)virt_addr = writeval;
    103 // read_result = *(volatile uint16_t*)virt_addr;
    104 break;
    105 case 32:
    106 *(volatile uint32_t*)virt_addr = writeval;
    107 // read_result = *(volatile uint32_t*)virt_addr;
    108 break;
    109 case 64:
    110 *(volatile uint64_t*)virt_addr = writeval;
    111 // read_result = *(volatile uint64_t*)virt_addr;
    112 break;
    113 default:
    114 bb_error_msg_and_die("bad width");
    115 }
    116 // printf("Written 0x%llX; readback 0x%llX\n",
    117 // (unsigned long long)writeval,
    118 // (unsigned long long)read_result);
    119 }
    120
    121 if (ENABLE_FEATURE_CLEAN_UP) {
    122 if (munmap(map_base, page_size * 2) == -1)
    123 bb_perror_msg_and_die("munmap");
    124 close(fd);
    125 }
    126
    127 return EXIT_SUCCESS;
    128 }