pp.c

GDB Remote Stub Backend for debugging an embedded ARM system via JTAG common hardware debug interfac

/*
 *  Copyright (C) 2004 Tobias Lorenz
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

/* parallel port interface */

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/ppdev.h>

#include "pp.h"


/*
   PP_Port+0: Data
   PP_Port+1: Status
   PP_Port+2: Control
*/


/*
 * linux pp access via direct hardware calls
 */

/* address of parallel port */
static unsigned int pp_direct_port;

/* macros for inb and outb */
static __inline unsigned char pp_direct_inb(void)
{
	unsigned char _v;

	__asm__ __volatile__ ("inb %w1,%0":"=a" (_v):"Nd" (pp_direct_port+1));
	return _v;
}

static __inline void pp_direct_outb(unsigned char value)
{
	__asm__ __volatile__ ("outb %b0,%w1": :"a" (value), "Nd" (pp_direct_port));
}

int pp_direct_init(unsigned int port)
{
	pp_direct_port = port;
	if (port == 0)
		port = 0x378;

	/* enable the use of the parallel port */
	if (ioperm(pp_direct_port, 3, 1) != 0) {
		printf ("ERROR: ioperm(0x%x) failed\n", pp_direct_port);
		return(-1);
	}
}

void pp_direct_done(void)
{
}


/*
 * linux pp access via /dev/parport?
 */

/* parallel port device */
static unsigned int pp_ppdev_fd = -1;

unsigned char pp_ppdev_inb(void)
{
	// PP_Port+1=Status
	unsigned char status;

	ioctl(pp_ppdev_fd, PPRSTATUS, &status);

	return(status);
}

void pp_ppdev_outb(unsigned char value)
{
	// PP_Port+0=Data
	ioctl(pp_ppdev_fd, PPWDATA, &value);
}

int pp_ppdev_init(unsigned char *device)
{
	if (!device)
		return(-1);

	if ((pp_ppdev_fd = open(device, O_RDWR)) == -1) {
		printf ("ERROR: open(%s) failed\n", device);
		return(-1);
	}

	if (ioctl(pp_ppdev_fd, PPCLAIM)) {
		printf ("ERROR: ioctl(PPCLAIM) failed\n");
		close(pp_ppdev_fd);
		return(-1);
	}
}

void pp_ppdev_done(void)
{
	ioctl(pp_ppdev_fd, PPRELEASE);
	close(pp_ppdev_fd);
}



/*
 * generic parallel port access
 */

unsigned char pp_inb(void)
{
	return pp_ppdev_inb();
}

void pp_outb(unsigned char value)
{
	pp_ppdev_outb(value);
}

void pp_init(void)
{
	pp_ppdev_init("/dev/parport0");
}

void pp_done(void)
{
	pp_ppdev_done();
}