dip4_driver.c

ARM9系列,s3c2410实验代码

/*
 *	dip4_driver.c - dip4 driver ( low-level )
 *	
 *	Author: 	li ming <[e-mail]>
 *	Date:		2005-6-11
 *	Copyleft:	http://www.lumit.org
 */

#include "dip4_driver.h"

/*  
; hardware connection
; PIO0 	PIO1 	PIO2 	PIO3	(gpio)
; 1  	2   	3   	4 	(dip4)
; so output value = 0x0000000f = (0b0000 0000  0000 0000  0000 0000  0000 1111)
*/

/* set dip4 related gpio */
int dip4_open( void )
{
	// set gpio's direction: set IOPMOD register mode bit to 0 = input
	IOPMOD = IOPMOD & (~0x0000000F);
	
	return 0;
}

int dip4_read( char * buf, int count )
{	
	int i = 0;
	int dip4_value;
	
	// the count has exceeds the count of our board
	if( count > DIP4_NUM )
		return -1;
	
	// get low-4-bits of IOPDATA 	
	dip4_value = IOPDATA & 0x0F;
	
	for( i = 0; i < count; i++ )
		buf[i] = (dip4_value & ( 1 << i ))? 1 : 0;	
		
	return count;
}

int dip4_write( char * buf, int count )
{	
	// do nothing	
	return count;
}

int dip4_ioctl( unsigned int cmd, unsigned long arg )
{
	// do nothing 	
	return 0;
}

int dip4_release( void )
{
	// do nothing 
	return 0;	
}