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Annotation of Gnu-Mach/i386/pc/i16/i16_a20.c, revision 1.1

1.1     ! root        1: /* 
        !             2:  * Copyright (c) 1995-1994 The University of Utah and
        !             3:  * the Computer Systems Laboratory at the University of Utah (CSL).
        !             4:  * All rights reserved.
        !             5:  *
        !             6:  * Permission to use, copy, modify and distribute this software is hereby
        !             7:  * granted provided that (1) source code retains these copyright, permission,
        !             8:  * and disclaimer notices, and (2) redistributions including binaries
        !             9:  * reproduce the notices in supporting documentation, and (3) all advertising
        !            10:  * materials mentioning features or use of this software display the following
        !            11:  * acknowledgement: ``This product includes software developed by the
        !            12:  * Computer Systems Laboratory at the University of Utah.''
        !            13:  *
        !            14:  * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
        !            15:  * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
        !            16:  * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
        !            17:  *
        !            18:  * CSL requests users of this software to return to [email protected] any
        !            19:  * improvements that they make and grant CSL redistribution rights.
        !            20:  *
        !            21:  *      Author: Bryan Ford, University of Utah CSL
        !            22:  */
        !            23: 
        !            24: 
        !            25: #include <mach/machine/pio.h>
        !            26: #include <mach/machine/code16.h>
        !            27: 
        !            28: #include "i16_a20.h"
        !            29: 
        !            30: 
        !            31: /* Keyboard stuff for turning on the A20 address line (gak!).  */
        !            32: #define K_RDWR                 0x60            /* keyboard data & cmds (read/write) */
        !            33: #define K_STATUS       0x64            /* keyboard status (read-only) */
        !            34: #define K_CMD          0x64            /* keybd ctlr command (write-only) */
        !            35: 
        !            36: #define K_OBUF_FUL     0x01            /* output buffer full */
        !            37: #define K_IBUF_FUL     0x02            /* input buffer full */
        !            38: 
        !            39: #define KC_CMD_WIN     0xd0            /* read  output port */
        !            40: #define KC_CMD_WOUT    0xd1            /* write output port */
        !            41: 
        !            42: #define KB_ENABLE_A20  0xdf    /* Linux and my BIOS uses this,
        !            43:                                   and I trust them more than Mach 3.0,
        !            44:                                   but I'd like to know what the difference is
        !            45:                                   and if it matters.  */
        !            46:                        /*0x9f*/        /* enable A20,
        !            47:                                           enable output buffer full interrupt
        !            48:                                           enable data line
        !            49:                                           disable clock line */
        !            50: #define KB_DISABLE_A20 0xdd
        !            51: 
        !            52: 
        !            53: CODE16
        !            54: 
        !            55: 
        !            56: /*
        !            57:    This routine ensures that the keyboard command queue is empty
        !            58:    (after emptying the output buffers)
        !            59: 
        !            60:    No timeout is used - if this hangs there is something wrong with
        !            61:    the machine, and we probably couldn't proceed anyway.
        !            62:    XXX should at least die properly
        !            63: */
        !            64: static void i16_empty_8042(void)
        !            65: {
        !            66:        int status;
        !            67: 
        !            68: retry:
        !            69:        i16_nanodelay(1000);
        !            70:        status = i16_inb(K_STATUS);
        !            71: 
        !            72:        if (status & K_OBUF_FUL)
        !            73:        {
        !            74:                i16_nanodelay(1000);
        !            75:                i16_inb(K_RDWR);
        !            76:                goto retry;
        !            77:        }
        !            78: 
        !            79:        if (status & K_IBUF_FUL)
        !            80:                goto retry;
        !            81: }
        !            82: 
        !            83: int i16_raw_test_a20(void);
        !            84: 
        !            85: /* Enable the A20 address line.  */
        !            86: void i16_raw_enable_a20(void)
        !            87: {
        !            88:        int v;
        !            89: 
        !            90:        /* XXX try int 15h function 24h */
        !            91: 
        !            92:        if (i16_raw_test_a20())
        !            93:                return;
        !            94: 
        !            95:        /* PS/2 */
        !            96:        v = i16_inb(0x92);
        !            97:        i16_nanodelay(1000);
        !            98:        i16_outb(0x92,v | 2);
        !            99: 
        !           100:        if (i16_raw_test_a20())
        !           101:                return;
        !           102: 
        !           103:        /* AT */
        !           104:        i16_empty_8042();
        !           105:        i16_outb(K_CMD, KC_CMD_WOUT);
        !           106:        i16_empty_8042();
        !           107:        i16_outb(K_RDWR, KB_ENABLE_A20);
        !           108:        i16_empty_8042();
        !           109: 
        !           110:        /* Wait until the a20 line gets enabled.  */
        !           111:        while (!i16_raw_test_a20());
        !           112: }
        !           113: 
        !           114: /* Disable the A20 address line.  */
        !           115: void i16_raw_disable_a20(void)
        !           116: {
        !           117:        int v;
        !           118: 
        !           119:        if (!i16_raw_test_a20())
        !           120:                return;
        !           121: 
        !           122:        /* PS/2 */
        !           123:        v = i16_inb(0x92);
        !           124:        i16_nanodelay(1000);
        !           125:        i16_outb(0x92, v & ~2);
        !           126: 
        !           127:        if (!i16_raw_test_a20())
        !           128:                return;
        !           129: 
        !           130:        /* AT */
        !           131:        i16_empty_8042();
        !           132:        i16_outb(K_CMD, KC_CMD_WOUT);
        !           133:        i16_empty_8042();
        !           134:        i16_outb(K_RDWR, KB_DISABLE_A20);
        !           135:        i16_empty_8042();
        !           136: 
        !           137:        /* Wait until the a20 line gets disabled.  */
        !           138:        while (i16_raw_test_a20());
        !           139: }
        !           140: 
        !           141: 
        !           142: void (*i16_enable_a20)(void) = i16_raw_enable_a20;
        !           143: void (*i16_disable_a20)(void) = i16_raw_disable_a20;
        !           144: 

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