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Annotation of sys/arch/amd64/stand/libsa/gateA20.c, Revision 1.1.1.1

1.1       nbrk        1: /*     $OpenBSD: gateA20.c,v 1.2 2004/03/21 21:37:41 tom Exp $ */
                      2:
                      3: /*
                      4:  * Ported to boot 386BSD by Julian Elischer (julian@tfs.com) Sept 1992
                      5:  *
                      6:  * Mach Operating System
                      7:  * Copyright (c) 1992, 1991 Carnegie Mellon University
                      8:  * All Rights Reserved.
                      9:  *
                     10:  * Permission to use, copy, modify and distribute this software and its
                     11:  * documentation is hereby granted, provided that both the copyright
                     12:  * notice and this permission notice appear in all copies of the
                     13:  * software, derivative works or modified versions, and any portions
                     14:  * thereof, and that both notices appear in supporting documentation.
                     15:  *
                     16:  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
                     17:  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
                     18:  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
                     19:  *
                     20:  * Carnegie Mellon requests users of this software to return to
                     21:  *
                     22:  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
                     23:  *  School of Computer Science
                     24:  *  Carnegie Mellon University
                     25:  *  Pittsburgh PA 15213-3890
                     26:  *
                     27:  * any improvements or extensions that they make and grant Carnegie Mellon
                     28:  * the rights to redistribute these changes.
                     29:  */
                     30:
                     31: #include <sys/param.h>
                     32: #include <sys/types.h>
                     33: #include <machine/pio.h>
                     34: #include <dev/ic/i8042reg.h>
                     35: #include <dev/isa/isareg.h>
                     36:
                     37: #include "libsa.h"
                     38:
                     39: int ps2model = 0;                      /* Not set in amd64 */
                     40:
                     41: #define KB_A20         0xdf            /* enable A20,
                     42:                                           enable output buffer full interrupt
                     43:                                           enable data line
                     44:                                           enable clock line */
                     45:
                     46:
                     47: /*
                     48:  * "Probe"-style routine (no parameters) to turn A20 on
                     49:  */
                     50: void
                     51: gateA20on(void)
                     52: {
                     53:        gateA20(1);
                     54: }
                     55:
                     56:
                     57: /*
                     58:  * Gate A20 for high memory
                     59:  */
                     60: void
                     61: gateA20(int on)
                     62: {
                     63:        if (ps2model == 0xf82 ||
                     64:            (inb(IO_KBD + KBSTATP) == 0xff && inb(IO_KBD + KBDATAP) == 0xff)) {
                     65:                int data;
                     66:
                     67:                /* Try to use 0x92 to turn on A20 */
                     68:                if (on) {
                     69:                        data = inb(0x92);
                     70:                        outb(0x92, data | 0x2);
                     71:                } else {
                     72:                        data = inb(0x92);
                     73:                        outb(0x92, data & ~0x2);
                     74:                }
                     75:        } else {
                     76:
                     77:                while (inb(IO_KBD + KBSTATP) & KBS_IBF);
                     78:
                     79:                while (inb(IO_KBD + KBSTATP) & KBS_DIB)
                     80:                        (void)inb(IO_KBD + KBDATAP);
                     81:
                     82:                outb(IO_KBD + KBCMDP, KBC_CMDWOUT);
                     83:                while (inb(IO_KBD + KBSTATP) & KBS_IBF);
                     84:
                     85:                if (on)
                     86:                        outb(IO_KBD + KBDATAP, KB_A20);
                     87:                else
                     88:                        outb(IO_KBD + KBDATAP, 0xcd);
                     89:                while (inb(IO_KBD + KBSTATP) & KBS_IBF);
                     90:
                     91:                while (inb(IO_KBD + KBSTATP) & KBS_DIB)
                     92:                        (void)inb(IO_KBD + KBDATAP);
                     93:        }
                     94: }