53 lines
1.2 KiB
C
53 lines
1.2 KiB
C
/*
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* $FreeBSD$
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* From: $NetBSD: gatea20.c,v 1.2 1997/10/29 00:32:49 fvdl Exp $
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*/
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/* extracted from freebsd:sys/i386/boot/biosboot/io.c */
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#include <stand.h>
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#include <machine/cpufunc.h>
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#include <bootstrap.h>
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#include "libi386.h"
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#define K_RDWR 0x60 /* keyboard data & cmds (read/write) */
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#define K_STATUS 0x64 /* keyboard status */
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#define K_CMD 0x64 /* keybd ctlr command (write-only) */
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#define K_OBUF_FUL 0x01 /* output buffer full */
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#define K_IBUF_FUL 0x02 /* input buffer full */
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#define KC_CMD_WIN 0xd0 /* read output port */
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#define KC_CMD_WOUT 0xd1 /* write output port */
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#define KB_A20 0x9f /* enable A20,
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reset (!),
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enable output buffer full interrupt
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enable data line
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disable clock line */
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/*
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* Gate A20 for high memory
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*/
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static unsigned char x_20 = KB_A20;
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void gateA20()
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{
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__asm("pushfl ; cli");
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#ifdef IBM_L40
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outb(0x92, 0x2);
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#else /* !IBM_L40 */
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while (inb(K_STATUS) & K_IBUF_FUL);
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while (inb(K_STATUS) & K_OBUF_FUL)
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(void)inb(K_RDWR);
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outb(K_CMD, KC_CMD_WOUT);
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delay(100);
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while (inb(K_STATUS) & K_IBUF_FUL);
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outb(K_RDWR, x_20);
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delay(100);
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while (inb(K_STATUS) & K_IBUF_FUL);
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#endif /* IBM_L40 */
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__asm("popfl");
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}
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