call_app.c

linux device driver example

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <unistd.h>

#define DEVICE_FILENAME  "/dev/calldev"

int main()
{
    int dev;
    char buff[128];
    int ret;

    printf( "1) device file open\n"); 
  
    dev = open( DEVICE_FILENAME, O_RDWR|O_NDELAY );
    if( dev >= 0 )
    {
        printf( "2) seek function call\n");
        
        ret = lseek( dev, 0x20, SEEK_SET );
        printf( "ret = %08X\n", ret );
     
        printf( "3) read function call\n");
        
        ret = read(dev,0x30, 0x31 );              
        printf( "ret = %08X\n", ret );
    
        printf( "4) write function call\n");
        ret = write(dev,0x40,0x41 );
        printf( "ret = %08X\n", ret );

        printf( "5) ioctl function call\n");
        ret = ioctl(dev, 0x51, 0x52 );
        printf( "ret = %08X\n", ret );

        printf( "6) device file close\n");
        ret = close(dev);
        printf( "ret = %08X\n", ret );
    }

    return 0;
}