source: packages/utils/devmem2/src/devmem2.c @ 22369

Last change on this file since 22369 was 22369, checked in by claudio, 6 years ago

[packages] add devmem2

File size: 3.7 KB
Line 
1/*
2 * devmem2.c: Simple program to read/write from/to any location in memory.
3 *
4 *  Copyright (C) 2000, Jan-Derk Bakker (J.D.Bakker@its.tudelft.nl)
5 *
6 *
7 * This software has been developed for the LART computing board
8 * (http://www.lart.tudelft.nl/). The development has been sponsored by
9 * the Mobile MultiMedia Communications (http://www.mmc.tudelft.nl/)
10 * and Ubiquitous Communications (http://www.ubicom.tudelft.nl/)
11 * projects.
12 *
13 * The author can be reached at:
14 *
15 *  Jan-Derk Bakker
16 *  Information and Communication Theory Group
17 *  Faculty of Information Technology and Systems
18 *  Delft University of Technology
19 *  P.O. Box 5031
20 *  2600 GA Delft
21 *  The Netherlands
22 *
23 *
24 * This program is free software; you can redistribute it and/or modify
25 * it under the terms of the GNU General Public License as published by
26 * the Free Software Foundation; either version 2 of the License, or
27 * (at your option) any later version.
28 *
29 * This program is distributed in the hope that it will be useful,
30 * but WITHOUT ANY WARRANTY; without even the implied warranty of
31 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
32 * GNU General Public License for more details.
33 *
34 * You should have received a copy of the GNU General Public License
35 * along with this program; if not, write to the Free Software
36 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
37 *
38 */
39
40#include <stdio.h>
41#include <stdlib.h>
42#include <unistd.h>
43#include <string.h>
44#include <errno.h>
45#include <signal.h>
46#include <fcntl.h>
47#include <ctype.h>
48#include <termios.h>
49#include <sys/types.h>
50#include <sys/mman.h>
51 
52#define FATAL do { fprintf(stderr, "Error at line %d, file %s (%d) [%s]\n", \
53  __LINE__, __FILE__, errno, strerror(errno)); exit(1); } while(0)
54 
55#define MAP_SIZE 4096UL
56#define MAP_MASK (MAP_SIZE - 1)
57
58int main(int argc, char **argv) {
59        int fd;
60        void *map_base, *virt_addr; 
61        unsigned long read_result, writeval;
62        off_t target;
63        int access_type = 'w';
64       
65        if(argc < 2) {
66                fprintf(stderr, "\nUsage:\t%s { address } [ type [ data ] ]\n"
67                        "\taddress : memory address to act upon\n"
68                        "\ttype : access operation type : [b]yte, [h]alfword, [w]ord\n"
69                        "\tdata : data to be written\n\n",
70                        argv[0]);
71                exit(1);
72        }
73        target = strtoul(argv[1], 0, 0);
74
75        if(argc > 2)
76                access_type = tolower(argv[2][0]);
77
78
79        if((fd = open("/dev/mem", O_RDWR | O_SYNC)) == -1) FATAL;
80        printf("/dev/mem opened.\n"); 
81        fflush(stdout);
82       
83        /* Map one page */
84        map_base = mmap(0, MAP_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, target & ~MAP_MASK);
85        if(map_base == (void *) -1) FATAL;
86        printf("Memory mapped at address %p.\n", map_base); 
87        fflush(stdout);
88       
89        virt_addr = map_base + (target & MAP_MASK);
90        switch(access_type) {
91                case 'b':
92                        read_result = *((unsigned char *) virt_addr);
93                        break;
94                case 'h':
95                        read_result = *((unsigned short *) virt_addr);
96                        break;
97                case 'w':
98                        read_result = *((unsigned long *) virt_addr);
99                        break;
100                default:
101                        fprintf(stderr, "Illegal data type '%c'.\n", access_type);
102                        exit(2);
103        }
104        printf("Value at address 0x%lX (%p): 0x%lX\n", target, virt_addr, read_result); 
105        fflush(stdout);
106
107        if(argc > 3) {
108                writeval = strtoul(argv[3], 0, 0);
109                switch(access_type) {
110                        case 'b':
111                                *((unsigned char *) virt_addr) = writeval;
112                                read_result = *((unsigned char *) virt_addr);
113                                break;
114                        case 'h':
115                                *((unsigned short *) virt_addr) = writeval;
116                                read_result = *((unsigned short *) virt_addr);
117                                break;
118                        case 'w':
119                                *((unsigned long *) virt_addr) = writeval;
120                                read_result = *((unsigned long *) virt_addr);
121                                break;
122                }
123                printf("Written 0x%lX; readback 0x%lX\n", writeval, read_result); 
124                fflush(stdout);
125        }
126       
127        if(munmap(map_base, MAP_SIZE) == -1) FATAL;
128        close(fd);
129        return 0;
130}
131
132
Note: See TracBrowser for help on using the repository browser.