source: branches/3.2/mindi-busybox/miscutils/devmem.c @ 3232

Last change on this file since 3232 was 3232, checked in by bruno, 5 years ago
  • Update mindi-busybox to 1.21.1
  • Property svn:eol-style set to native
File size: 3.8 KB
Line 
1/*
2 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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//usage:#define devmem_trivial_usage
8//usage:    "ADDRESS [WIDTH [VALUE]]"
9//usage:#define devmem_full_usage "\n\n"
10//usage:       "Read/write from physical address\n"
11//usage:     "\n    ADDRESS Address to act upon"
12//usage:     "\n    WIDTH   Width (8/16/...)"
13//usage:     "\n    VALUE   Data to be written"
14
15#include "libbb.h"
16
17int devmem_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
18int devmem_main(int argc UNUSED_PARAM, char **argv)
19{
20    void *map_base, *virt_addr;
21    uint64_t read_result;
22    uint64_t writeval = writeval; /* for compiler */
23    off_t target;
24    unsigned page_size, mapped_size, offset_in_page;
25    int fd;
26    unsigned width = 8 * sizeof(int);
27
28    /* devmem ADDRESS [WIDTH [VALUE]] */
29// TODO: options?
30// -r: read and output only the value in hex, with 0x prefix
31// -w: write only, no reads before or after, and no output
32// or make this behavior default?
33// Let's try this and see how users react.
34
35    /* ADDRESS */
36    if (!argv[1])
37        bb_show_usage();
38    errno = 0;
39    target = bb_strtoull(argv[1], NULL, 0); /* allows hex, oct etc */
40
41    /* WIDTH */
42    if (argv[2]) {
43        if (isdigit(argv[2][0]) || argv[2][1])
44            width = xatou(argv[2]);
45        else {
46            static const char bhwl[] ALIGN1 = "bhwl";
47            static const uint8_t sizes[] ALIGN1 = {
48                8 * sizeof(char),
49                8 * sizeof(short),
50                8 * sizeof(int),
51                8 * sizeof(long),
52                0 /* bad */
53            };
54            width = strchrnul(bhwl, (argv[2][0] | 0x20)) - bhwl;
55            width = sizes[width];
56        }
57        /* VALUE */
58        if (argv[3])
59            writeval = bb_strtoull(argv[3], NULL, 0);
60    } else { /* argv[2] == NULL */
61        /* make argv[3] to be a valid thing to fetch */
62        argv--;
63    }
64    if (errno)
65        bb_show_usage(); /* one of bb_strtouXX failed */
66
67    fd = xopen("/dev/mem", argv[3] ? (O_RDWR | O_SYNC) : (O_RDONLY | O_SYNC));
68    mapped_size = page_size = getpagesize();
69    offset_in_page = (unsigned)target & (page_size - 1);
70    if (offset_in_page + width > page_size) {
71        /* This access spans pages.
72         * Must map two pages to make it possible: */
73        mapped_size *= 2;
74    }
75    map_base = mmap(NULL,
76            mapped_size,
77            argv[3] ? (PROT_READ | PROT_WRITE) : PROT_READ,
78            MAP_SHARED,
79            fd,
80            target & ~(off_t)(page_size - 1));
81    if (map_base == MAP_FAILED)
82        bb_perror_msg_and_die("mmap");
83
84//  printf("Memory mapped at address %p.\n", map_base);
85
86    virt_addr = (char*)map_base + offset_in_page;
87
88    if (!argv[3]) {
89        switch (width) {
90        case 8:
91            read_result = *(volatile uint8_t*)virt_addr;
92            break;
93        case 16:
94            read_result = *(volatile uint16_t*)virt_addr;
95            break;
96        case 32:
97            read_result = *(volatile uint32_t*)virt_addr;
98            break;
99        case 64:
100            read_result = *(volatile uint64_t*)virt_addr;
101            break;
102        default:
103            bb_error_msg_and_die("bad width");
104        }
105//      printf("Value at address 0x%"OFF_FMT"X (%p): 0x%llX\n",
106//          target, virt_addr,
107//          (unsigned long long)read_result);
108        /* Zero-padded output shows the width of access just done */
109        printf("0x%0*llX\n", (width >> 2), (unsigned long long)read_result);
110    } else {
111        switch (width) {
112        case 8:
113            *(volatile uint8_t*)virt_addr = writeval;
114//          read_result = *(volatile uint8_t*)virt_addr;
115            break;
116        case 16:
117            *(volatile uint16_t*)virt_addr = writeval;
118//          read_result = *(volatile uint16_t*)virt_addr;
119            break;
120        case 32:
121            *(volatile uint32_t*)virt_addr = writeval;
122//          read_result = *(volatile uint32_t*)virt_addr;
123            break;
124        case 64:
125            *(volatile uint64_t*)virt_addr = writeval;
126//          read_result = *(volatile uint64_t*)virt_addr;
127            break;
128        default:
129            bb_error_msg_and_die("bad width");
130        }
131//      printf("Written 0x%llX; readback 0x%llX\n",
132//              (unsigned long long)writeval,
133//              (unsigned long long)read_result);
134    }
135
136    if (ENABLE_FEATURE_CLEAN_UP) {
137        if (munmap(map_base, mapped_size) == -1)
138            bb_perror_msg_and_die("munmap");
139        close(fd);
140    }
141
142    return EXIT_SUCCESS;
143}
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