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25#include "libbb.h"
26
27int devmem_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
28int devmem_main(int argc UNUSED_PARAM, char **argv)
29{
30 void *map_base, *virt_addr;
31 uint64_t read_result;
32 uint64_t writeval = writeval;
33 off_t target;
34 unsigned page_size, mapped_size, offset_in_page;
35 int fd;
36 unsigned width = 8 * sizeof(int);
37
38
39
40
41
42
43
44
45
46 if (!argv[1])
47 bb_show_usage();
48 errno = 0;
49 target = bb_strtoull(argv[1], NULL, 0);
50
51
52 if (argv[2]) {
53 if (isdigit(argv[2][0]) || argv[2][1])
54 width = xatou(argv[2]);
55 else {
56 static const char bhwl[] ALIGN1 = "bhwl";
57 static const uint8_t sizes[] ALIGN1 = {
58 8 * sizeof(char),
59 8 * sizeof(short),
60 8 * sizeof(int),
61 8 * sizeof(long),
62 0
63 };
64 width = strchrnul(bhwl, (argv[2][0] | 0x20)) - bhwl;
65 width = sizes[width];
66 }
67
68 if (argv[3])
69 writeval = bb_strtoull(argv[3], NULL, 0);
70 } else {
71
72 argv--;
73 }
74 if (errno)
75 bb_show_usage();
76
77 fd = xopen("/dev/mem", argv[3] ? (O_RDWR | O_SYNC) : (O_RDONLY | O_SYNC));
78 mapped_size = page_size = getpagesize();
79 offset_in_page = (unsigned)target & (page_size - 1);
80 if (offset_in_page + width > page_size) {
81
82
83 mapped_size *= 2;
84 }
85 map_base = mmap(NULL,
86 mapped_size,
87 argv[3] ? (PROT_READ | PROT_WRITE) : PROT_READ,
88 MAP_SHARED,
89 fd,
90 target & ~(off_t)(page_size - 1));
91 if (map_base == MAP_FAILED)
92 bb_perror_msg_and_die("mmap");
93
94
95
96 virt_addr = (char*)map_base + offset_in_page;
97
98 if (!argv[3]) {
99 switch (width) {
100 case 8:
101 read_result = *(volatile uint8_t*)virt_addr;
102 break;
103 case 16:
104 read_result = *(volatile uint16_t*)virt_addr;
105 break;
106 case 32:
107 read_result = *(volatile uint32_t*)virt_addr;
108 break;
109 case 64:
110 read_result = *(volatile uint64_t*)virt_addr;
111 break;
112 default:
113 bb_error_msg_and_die("bad width");
114 }
115
116
117
118
119 printf("0x%0*llX\n", (width >> 2), (unsigned long long)read_result);
120 } else {
121 switch (width) {
122 case 8:
123 *(volatile uint8_t*)virt_addr = writeval;
124
125 break;
126 case 16:
127 *(volatile uint16_t*)virt_addr = writeval;
128
129 break;
130 case 32:
131 *(volatile uint32_t*)virt_addr = writeval;
132
133 break;
134 case 64:
135 *(volatile uint64_t*)virt_addr = writeval;
136
137 break;
138 default:
139 bb_error_msg_and_die("bad width");
140 }
141
142
143
144 }
145
146 if (ENABLE_FEATURE_CLEAN_UP) {
147 if (munmap(map_base, mapped_size) == -1)
148 bb_perror_msg_and_die("munmap");
149 close(fd);
150 }
151
152 return EXIT_SUCCESS;
153}
154