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gatea20.c revision 1.2.14.1 
      1 /*	$NetBSD: gatea20.c,v 1.2.14.1 2000/11/20 20:09:40 bouyer Exp $	*/
      2 
      3 /* extracted from freebsd:sys/i386/boot/biosboot/io.c */
      4 
      5 #include <sys/types.h>
      6 #include <machine/pio.h>
      7 
      8 #include <lib/libsa/stand.h>
      9 
     10 #include "libi386.h"
     11 
     12 #define K_RDWR 		0x60		/* keyboard data & cmds (read/write) */
     13 #define K_STATUS 	0x64		/* keyboard status */
     14 #define K_CMD	 	0x64		/* keybd ctlr command (write-only) */
     15 
     16 #define K_OBUF_FUL 	0x01		/* output buffer full */
     17 #define K_IBUF_FUL 	0x02		/* input buffer full */
     18 
     19 #define KC_CMD_WIN	0xd0		/* read  output port */
     20 #define KC_CMD_WOUT	0xd1		/* write output port */
     21 #define KB_A20		0x9f		/* enable A20,
     22 					   reset (!),
     23 					   enable output buffer full interrupt
     24 					   enable data line
     25 					   disable clock line */
     26 
     27 /*
     28  * Gate A20 for high memory
     29  */
     30 #ifndef IBM_L40
     31 static unsigned char	x_20 = KB_A20;
     32 #endif
     33 void gateA20()
     34 {
     35 	__asm("pushfl ; cli");
     36 #ifdef	IBM_L40
     37 	outb(0x92, 0x2);
     38 #else	/* !IBM_L40 */
     39 	while (inb(K_STATUS) & K_IBUF_FUL);
     40 	while (inb(K_STATUS) & K_OBUF_FUL)
     41 		(void)inb(K_RDWR);
     42 
     43 	outb(K_CMD, KC_CMD_WOUT);
     44 	delay(100);
     45 	while (inb(K_STATUS) & K_IBUF_FUL);
     46 	outb(K_RDWR, x_20);
     47 	delay(100);
     48 	while (inb(K_STATUS) & K_IBUF_FUL);
     49 #endif	/* IBM_L40 */
     50 	__asm("popfl");
     51 }
     52