Contents of /tags/mkinitrd-6_3_0/busybox/miscutils/devmem.c
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Thu Aug 19 10:14:02 2010 UTC (14 years, 1 month ago) by niro
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File size: 3649 byte(s)
Thu Aug 19 10:14:02 2010 UTC (14 years, 1 month ago) by niro
File MIME type: text/plain
File size: 3649 byte(s)
tagged 'mkinitrd-6_3_0'
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, mapped_size, offset_in_page; |
17 | int fd; |
18 | unsigned 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 fetch */ |
54 | argv--; |
55 | } |
56 | if (errno) |
57 | bb_show_usage(); /* one of bb_strtouXX failed */ |
58 | |
59 | fd = xopen("/dev/mem", argv[3] ? (O_RDWR | O_SYNC) : (O_RDONLY | O_SYNC)); |
60 | mapped_size = page_size = getpagesize(); |
61 | offset_in_page = (unsigned)target & (page_size - 1); |
62 | if (offset_in_page + width > page_size) { |
63 | /* This access spans pages. |
64 | * Must map two pages to make it possible: */ |
65 | mapped_size *= 2; |
66 | } |
67 | map_base = mmap(NULL, |
68 | mapped_size, |
69 | argv[3] ? (PROT_READ | PROT_WRITE) : PROT_READ, |
70 | MAP_SHARED, |
71 | fd, |
72 | target & ~(off_t)(page_size - 1)); |
73 | if (map_base == MAP_FAILED) |
74 | bb_perror_msg_and_die("mmap"); |
75 | |
76 | // printf("Memory mapped at address %p.\n", map_base); |
77 | |
78 | virt_addr = (char*)map_base + offset_in_page; |
79 | |
80 | if (!argv[3]) { |
81 | switch (width) { |
82 | case 8: |
83 | read_result = *(volatile uint8_t*)virt_addr; |
84 | break; |
85 | case 16: |
86 | read_result = *(volatile uint16_t*)virt_addr; |
87 | break; |
88 | case 32: |
89 | read_result = *(volatile uint32_t*)virt_addr; |
90 | break; |
91 | case 64: |
92 | read_result = *(volatile uint64_t*)virt_addr; |
93 | break; |
94 | default: |
95 | bb_error_msg_and_die("bad width"); |
96 | } |
97 | // printf("Value at address 0x%"OFF_FMT"X (%p): 0x%llX\n", |
98 | // target, virt_addr, |
99 | // (unsigned long long)read_result); |
100 | /* Zero-padded output shows the width of access just done */ |
101 | printf("0x%0*llX\n", (width >> 2), (unsigned long long)read_result); |
102 | } else { |
103 | switch (width) { |
104 | case 8: |
105 | *(volatile uint8_t*)virt_addr = writeval; |
106 | // read_result = *(volatile uint8_t*)virt_addr; |
107 | break; |
108 | case 16: |
109 | *(volatile uint16_t*)virt_addr = writeval; |
110 | // read_result = *(volatile uint16_t*)virt_addr; |
111 | break; |
112 | case 32: |
113 | *(volatile uint32_t*)virt_addr = writeval; |
114 | // read_result = *(volatile uint32_t*)virt_addr; |
115 | break; |
116 | case 64: |
117 | *(volatile uint64_t*)virt_addr = writeval; |
118 | // read_result = *(volatile uint64_t*)virt_addr; |
119 | break; |
120 | default: |
121 | bb_error_msg_and_die("bad width"); |
122 | } |
123 | // printf("Written 0x%llX; readback 0x%llX\n", |
124 | // (unsigned long long)writeval, |
125 | // (unsigned long long)read_result); |
126 | } |
127 | |
128 | if (ENABLE_FEATURE_CLEAN_UP) { |
129 | if (munmap(map_base, mapped_size) == -1) |
130 | bb_perror_msg_and_die("munmap"); |
131 | close(fd); |
132 | } |
133 | |
134 | return EXIT_SUCCESS; |
135 | } |