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Diffstat (limited to 'devmem2.c')
| -rw-r--r-- | devmem2.c | 131 |
1 files changed, 131 insertions, 0 deletions
diff --git a/devmem2.c b/devmem2.c new file mode 100644 index 0000000..7732ecb --- /dev/null +++ b/devmem2.c @@ -0,0 +1,131 @@ +/* + * devmem2.c: Simple program to read/write from/to any location in memory. + * + * Copyright (C) 2000, Jan-Derk Bakker (J.D.Bakker@its.tudelft.nl) + * + * + * This software has been developed for the LART computing board + * (http://www.lart.tudelft.nl/). The development has been sponsored by + * the Mobile MultiMedia Communications (http://www.mmc.tudelft.nl/) + * and Ubiquitous Communications (http://www.ubicom.tudelft.nl/) + * projects. + * + * The author can be reached at: + * + * Jan-Derk Bakker + * Information and Communication Theory Group + * Faculty of Information Technology and Systems + * Delft University of Technology + * P.O. Box 5031 + * 2600 GA Delft + * The Netherlands + * + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + * + */ + +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> +#include <string.h> +#include <errno.h> +#include <signal.h> +#include <fcntl.h> +#include <ctype.h> +#include <termios.h> +#include <sys/types.h> +#include <sys/mman.h> + +#define FATAL do { fprintf(stderr, "Error at line %d, file %s (%d) [%s]\n", \ + __LINE__, __FILE__, errno, strerror(errno)); exit(1); } while(0) + +#define MAP_SIZE 4096UL +#define MAP_MASK (MAP_SIZE - 1) + +int main(int argc, char **argv) { + int fd; + void *map_base, *virt_addr; + unsigned long read_result, writeval; + off_t target; + int access_type = 'w'; + + if(argc < 2) { + fprintf(stderr, "\nUsage:\t%s { address } [ type [ data ] ]\n" + "\taddress : memory address to act upon\n" + "\ttype : access operation type : [b]yte, [h]alfword, [w]ord\n" + "\tdata : data to be written\n\n", + argv[0]); + exit(1); + } + target = strtoul(argv[1], 0, 0); + + if(argc > 2) + access_type = tolower(argv[2][0]); + + + if((fd = open("/dev/mem", O_RDWR | O_SYNC)) == -1) FATAL; + printf("/dev/mem opened.\n"); + fflush(stdout); + + /* Map one page */ + map_base = mmap(0, MAP_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, target & ~MAP_MASK); + if(map_base == (void *) -1) FATAL; + printf("Memory mapped at address %p.\n", map_base); + fflush(stdout); + + virt_addr = map_base + (target & MAP_MASK); + switch(access_type) { + case 'b': + read_result = *((unsigned char *) virt_addr); + break; + case 'h': + read_result = *((unsigned short *) virt_addr); + break; + case 'w': + read_result = *((unsigned long *) virt_addr); + break; + default: + fprintf(stderr, "Illegal data type '%c'.\n", access_type); + exit(2); + } + printf("Value at address 0x%X (%p): 0x%X\n", target, virt_addr, read_result); + fflush(stdout); + + if(argc > 3) { + writeval = strtoul(argv[3], 0, 0); + switch(access_type) { + case 'b': + *((unsigned char *) virt_addr) = writeval; + read_result = *((unsigned char *) virt_addr); + break; + case 'h': + *((unsigned short *) virt_addr) = writeval; + read_result = *((unsigned short *) virt_addr); + break; + case 'w': + *((unsigned long *) virt_addr) = writeval; + read_result = *((unsigned long *) virt_addr); + break; + } + printf("Written 0x%X; readback 0x%X\n", writeval, read_result); + fflush(stdout); + } + + if(munmap(map_base, MAP_SIZE) == -1) FATAL; + close(fd); + return 0; +} + |