2 * devmem2.c: Simple program to read/write from/to any location in memory.
4 * Copyright (C) 2000, Jan-Derk Bakker (J.D.Bakker@its.tudelft.nl)
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/)
13 * The author can be reached at:
16 * Information and Communication Theory Group
17 * Faculty of Information Technology and Systems
18 * Delft University of Technology
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.
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.
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
49 #include <sys/types.h>
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)
55 #define MAP_SIZE 4096UL
56 #define MAP_MASK (MAP_SIZE - 1)
58 int main(int argc, char **argv) {
60 void *map_base, *virt_addr;
61 unsigned long read_result, writeval;
63 int access_type = 'w';
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",
73 target = strtoul(argv[1], 0, 0);
76 access_type = tolower(argv[2][0]);
79 if((fd = open("/dev/mem", O_RDWR | O_SYNC)) == -1) FATAL;
80 printf("/dev/mem opened.\n");
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);
89 virt_addr = map_base + (target & MAP_MASK);
92 read_result = *((unsigned char *) virt_addr);
95 read_result = *((unsigned short *) virt_addr);
98 read_result = *((unsigned long *) virt_addr);
101 fprintf(stderr, "Illegal data type '%c'.\n", access_type);
104 printf("Value at address 0x%lX (%p): 0x%lX\n", target, virt_addr, read_result);
108 writeval = strtoul(argv[3], 0, 0);
109 switch(access_type) {
111 *((unsigned char *) virt_addr) = writeval;
112 read_result = *((unsigned char *) virt_addr);
115 *((unsigned short *) virt_addr) = writeval;
116 read_result = *((unsigned short *) virt_addr);
119 *((unsigned long *) virt_addr) = writeval;
120 read_result = *((unsigned long *) virt_addr);
123 printf("Written 0x%lX; readback 0x%lX\n", writeval, read_result);
127 if(munmap(map_base, MAP_SIZE) == -1) FATAL;