i386/libsaio/misc.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*
  26  * Mach Operating System
  27  * Copyright (c) 1990 Carnegie-Mellon University
  28  * Copyright (c) 1989 Carnegie-Mellon University
  29  * All rights reserved.  The CMU software License Agreement specifies
  30  * the terms and conditions for use and redistribution.
  31  */
  32
  33 /*
  34  *                      INTEL CORPORATION PROPRIETARY INFORMATION
  35  *
  36  *      This software is supplied under the terms of a license  agreement or
  37  *      nondisclosure agreement with Intel Corporation and may not be copied
  38  *      nor disclosed except in accordance with the terms of that agreement.
  39  *
  40  *      Copyright 1988, 1989 Intel Corporation
  41  */
  42
  43 /*
  44  * Copyright 1993 NeXT, Inc.
  45  * All rights reserved.
  46  */
  47
  48 #include "libsaio.h"
  49
  50 /*
  51  * keyboard controller (8042) I/O port addresses
  52  */
  53 #define PORT_A      0x60    /* port A */
  54 #define PORT_B      0x64    /* port B */
  55
  56 /*
  57  * keyboard controller command
  58  */
  59 #define CMD_WOUT    0xd1    /* write controller's output port */
  60
  61 /*
  62  * keyboard controller status flags
  63  */
  64 #define KB_INFULL   0x2     /* input buffer full */
  65 #define KB_OUTFULL  0x1     /* output buffer full */
  66
  67 #define KB_A20      0x9f    /* enable A20,
  68                                enable output buffer full interrupt
  69                                enable data line
  70                                disable clock line */
  71
  72 //==========================================================================
  73 // Enable A20 gate to be able to access memory above 1MB
  74
  75 void enableA20()
  76 {
  77     /* make sure that the input buffer is empty */
  78     while (inb(PORT_B) & KB_INFULL);
  79
  80     /* make sure that the output buffer is empty */
  81     if (inb(PORT_B) & KB_OUTFULL)
  82         (void)inb(PORT_A);
  83
  84     /* make sure that the input buffer is empty */
  85     while (inb(PORT_B) & KB_INFULL);
  86
  87     /* write output port */
  88     outb(PORT_B, CMD_WOUT);
  89     delay(100);
  90
  91     /* wait until command is accepted */
  92     while (inb(PORT_B) & KB_INFULL);
  93
  94     outb(PORT_A, KB_A20);
  95     delay(100);
  96
  97     while (inb(PORT_B) & KB_INFULL);   /* wait until done */
  98 }