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/*
* Copyright (c) 1995-1994 The University of Utah and
* the Computer Systems Laboratory at the University of Utah (CSL).
* All rights reserved.
*
* Permission to use, copy, modify and distribute this software is hereby
* granted provided that (1) source code retains these copyright, permission,
* and disclaimer notices, and (2) redistributions including binaries
* reproduce the notices in supporting documentation, and (3) all advertising
* materials mentioning features or use of this software display the following
* acknowledgement: ``This product includes software developed by the
* Computer Systems Laboratory at the University of Utah.''
*
* THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
* IS" CONDITION. THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
* ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* CSL requests users of this software to return to csl-dist@cs.utah.edu any
* improvements that they make and grant CSL redistribution rights.
*
* Author: Bryan Ford, University of Utah CSL
*/
#include <mach/machine/pio.h>
#include <mach/machine/code16.h>
#include "i16_a20.h"
/* Keyboard stuff for turning on the A20 address line (gak!). */
#define K_RDWR 0x60 /* keyboard data & cmds (read/write) */
#define K_STATUS 0x64 /* keyboard status (read-only) */
#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_ENABLE_A20 0xdf /* Linux and my BIOS uses this,
and I trust them more than Mach 3.0,
but I'd like to know what the difference is
and if it matters. */
/*0x9f*/ /* enable A20,
enable output buffer full interrupt
enable data line
disable clock line */
#define KB_DISABLE_A20 0xdd
CODE16
/*
This routine ensures that the keyboard command queue is empty
(after emptying the output buffers)
No timeout is used - if this hangs there is something wrong with
the machine, and we probably couldn't proceed anyway.
XXX should at least die properly
*/
static void i16_empty_8042(void)
{
int status;
retry:
i16_nanodelay(1000);
status = i16_inb(K_STATUS);
if (status & K_OBUF_FUL)
{
i16_nanodelay(1000);
i16_inb(K_RDWR);
goto retry;
}
if (status & K_IBUF_FUL)
goto retry;
}
int i16_raw_test_a20(void);
/* Enable the A20 address line. */
void i16_raw_enable_a20(void)
{
int v;
/* XXX try int 15h function 24h */
if (i16_raw_test_a20())
return;
/* PS/2 */
v = i16_inb(0x92);
i16_nanodelay(1000);
i16_outb(0x92,v | 2);
if (i16_raw_test_a20())
return;
/* AT */
i16_empty_8042();
i16_outb(K_CMD, KC_CMD_WOUT);
i16_empty_8042();
i16_outb(K_RDWR, KB_ENABLE_A20);
i16_empty_8042();
/* Wait until the a20 line gets enabled. */
while (!i16_raw_test_a20());
}
/* Disable the A20 address line. */
void i16_raw_disable_a20(void)
{
int v;
if (!i16_raw_test_a20())
return;
/* PS/2 */
v = i16_inb(0x92);
i16_nanodelay(1000);
i16_outb(0x92, v & ~2);
if (!i16_raw_test_a20())
return;
/* AT */
i16_empty_8042();
i16_outb(K_CMD, KC_CMD_WOUT);
i16_empty_8042();
i16_outb(K_RDWR, KB_DISABLE_A20);
i16_empty_8042();
/* Wait until the a20 line gets disabled. */
while (i16_raw_test_a20());
}
void (*i16_enable_a20)(void) = i16_raw_enable_a20;
void (*i16_disable_a20)(void) = i16_raw_disable_a20;
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