/*	$OpenBSD: gateA20.c,v 1.2 1997/03/31 03:12:13 weingart Exp $	*/

/*
 * Ported to boot 386BSD by Julian Elischer (julian@tfs.com) Sept 1992
 *
 * Mach Operating System
 * Copyright (c) 1992, 1991 Carnegie Mellon University
 * All Rights Reserved.
 * 
 * Permission to use, copy, modify and distribute this software and its
 * documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 * 
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 * 
 * Carnegie Mellon requests users of this software to return to
 * 
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 * 
 * any improvements or extensions that they make and grant Carnegie Mellon
 * the rights to redistribute these changes.
 */

#include <sys/types.h>
#include <machine/pio.h>
#include <stand.h>

#define K_RDWR 		0x60		/* keyboard data & cmds (read/write) */
#define K_STATUS 	0x64		/* keyboard status */
#define K_CMD	 	0x64		/* keybd ctlr command (write-only) */

#define K_OBUF_FUL 	0x01		/* output buffer full */
#define K_IBUF_FUL 	0x02		/* input buffer full */

#define KC_CMD_WIN	0xd0		/* read  output port */
#define KC_CMD_WOUT	0xd1		/* write output port */
#define KB_A20		0xdf		/* enable A20,
					   enable output buffer full interrupt
					   enable data line
					   enable clock line */

/*
 * Gate A20 for high memory
 */
void
gateA20(on)
	int on;
{
#ifdef	IBM_L40
	outb(0x92, 0x2);
#else	IBM_L40
	while (inb(K_STATUS) & K_IBUF_FUL);

	while (inb(K_STATUS) & K_OBUF_FUL)
		(void)inb(K_RDWR);

	outb(K_CMD, KC_CMD_WOUT);
	while (inb(K_STATUS) & K_IBUF_FUL);

	if (on)
		outb(K_RDWR, KB_A20);
	else
		outb(K_RDWR, 0xcd);
	while (inb(K_STATUS) & K_IBUF_FUL);

	while (inb(K_STATUS) & K_OBUF_FUL)
		(void)inb(K_RDWR);
#endif	IBM_L40
}