blob: ecd873896342da3981bec0e665fe417c94e1d7c4
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 | |
17 | int devmem_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
18 | int devmem_main(int argc UNUSED_PARAM, char **argv) |
19 | { |
20 | void *map_base, *virt_addr; |
21 | uint64_t read_result; |
22 | uint64_t writeval = 0; |
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 | } |
144 |