i386/libsaio/misc.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
   7  * Reserved.  This file contains Original Code and/or Modifications of
   8  * Original Code as defined in and that are subject to the Apple Public
   9  * Source License Version 1.1 (the "License").  You may not use this file
  10  * except in compliance with the License.  Please obtain a copy of the
  11  * License at http://www.apple.com/publicsource and read it before using
  12  * this file.
  13  *
  14  * The Original Code and all software distributed under the License are
  15  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  16  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  17  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE OR NON- INFRINGEMENT.  Please see the
  19  * License for the specific language governing rights and limitations
  20  * under the License.
  21  *
  22  * @APPLE_LICENSE_HEADER_END@
  23  */
  24 /*
  25  * Mach Operating System
  26  * Copyright (c) 1990 Carnegie-Mellon University
  27  * Copyright (c) 1989 Carnegie-Mellon University
  28  * All rights reserved.  The CMU software License Agreement specifies
  29  * the terms and conditions for use and redistribution.
  30  */
  31
  32 /*
  33  *                      INTEL CORPORATION PROPRIETARY INFORMATION
  34  *
  35  *      This software is supplied under the terms of a license  agreement or
  36  *      nondisclosure agreement with Intel Corporation and may not be copied
  37  *      nor disclosed except in accordance with the terms of that agreement.
  38  *
  39  *      Copyright 1988, 1989 Intel Corporation
  40  */
  41
  42 /*
  43  * Copyright 1993 NeXT, Inc.
  44  * All rights reserved.
  45  */
  46
  47 #include "libsaio.h"
  48
  49 /*
  50  * keyboard controller (8042) I/O port addresses
  51  */
  52 #define PORT_A      0x60    /* port A */
  53 #define PORT_B      0x64    /* port B */
  54
  55 /*
  56  * keyboard controller command
  57  */
  58 #define CMD_WOUT    0xd1    /* write controller's output port */
  59
  60 /*
  61  * keyboard controller status flags
  62  */
  63 #define KB_INFULL   0x2     /* input buffer full */
  64 #define KB_OUTFULL  0x1     /* output buffer full */
  65
  66 #define KB_A20      0x9f    /* enable A20,
  67                                enable output buffer full interrupt
  68                                enable data line
  69                                disable clock line */
  70
  71 //==========================================================================
  72 // Enable A20 gate to be able to access memory above 1MB
  73
  74 void enableA20()
  75 {
  76     /* make sure that the input buffer is empty */
  77     while (inb(PORT_B) & KB_INFULL);
  78
  79     /* make sure that the output buffer is empty */
  80     if (inb(PORT_B) & KB_OUTFULL)
  81         (void)inb(PORT_A);
  82
  83     /* make sure that the input buffer is empty */
  84     while (inb(PORT_B) & KB_INFULL);
  85
  86     /* write output port */
  87     outb(PORT_B, CMD_WOUT);
  88     delay(100);
  89
  90     /* wait until command is accepted */
  91     while (inb(PORT_B) & KB_INFULL);
  92
  93     outb(PORT_A, KB_A20);
  94     delay(100);
  95
  96     while (inb(PORT_B) & KB_INFULL);   /* wait until done */
  97 }