devmem2.c

/*
 * devmem2.c: Simple program to read/write from/to any location in memory.
 *
 *  Copyright (C) 2000, Jan-Derk Bakker (jdb@lartmaker.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.
 *
 *
 * 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)


// based on...
// http://stackoverflow.com/a/3974138/3152071

//assumes little endian

void int2binstr(char *buffer, size_t const size, void const * const ptr)
{
    unsigned char *b = (unsigned char*) ptr;
    unsigned char byte;
    int i, j;

    for (i=size-1;i>=0;i--)
    {
        for (j=7;j>=0;j--)
        {
            byte = (b[i] >> j) & 1;
            *buffer = '0' + byte;
            buffer++;
        }
        *buffer = ' ';		// makes it easier to see
        buffer++;
    }
    *buffer = 0x00;	// null terminal string
}

#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';

    char binstrbuffer[ (sizeof( unsigned long )*9) + 1]; // 8 bits per byte, space between bytes,  plus null terminator

    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);

    virt_addr = map_base + (target & MAP_MASK);

    printf("Address 0x%llx (%p):\n", (long long)target, virt_addr );
    fflush(stdout);


    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);
    }

    int2binstr( binstrbuffer , sizeof(  read_result ) , &read_result );
    printf("Read    : 0x%08lx 0b%s\n" , read_result , binstrbuffer );
    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;
        }

        int2binstr( binstrbuffer , sizeof(  writeval ) , &writeval );
        printf("Written : 0x%08lx 0b%s\n" , writeval , binstrbuffer );

        read_result = *((unsigned long *) virt_addr);
        int2binstr( binstrbuffer , sizeof(  read_result ) , &read_result );
        printf("Readback: 0x%08lx 0b%s\n" , read_result , binstrbuffer );

        read_result = *((unsigned long *) virt_addr);
        int2binstr( binstrbuffer , sizeof(  read_result ) , &read_result );
        printf("Readback: 0x%08lx 0b%s\n" , read_result , binstrbuffer );

        read_result = *((unsigned long *) virt_addr);
        int2binstr( binstrbuffer , sizeof(  read_result ) , &read_result );
        printf("Readback: 0x%08lx 0b%s\n" , read_result , binstrbuffer );

        read_result = *((unsigned long *) virt_addr);
        int2binstr( binstrbuffer , sizeof(  read_result ) , &read_result );
        printf("Readback: 0x%08lx 0b%s\n" , read_result , binstrbuffer );

        fflush(stdout);
    }


    if(munmap(map_base, MAP_SIZE) == -1) FATAL;
    close(fd);
    return 0;
}