1 files changed, 76 insertions, 0 deletions
diff --git a/sys/arch/i386/stand/libsa/gateA20.c b/sys/arch/i386/stand/libsa/gateA20.c
new file mode 100644
index 00000000000..7c3ac5a5fda
--- /dev/null
+++ b/sys/arch/i386/stand/libsa/gateA20.c
@@ -0,0 +1,76 @@
+/*	$OpenBSD: gateA20.c,v 1.2 1997/03/31 03:12:13 weingart Exp $	*/
+
+/*
+ * Ported to boot 386BSD by Julian Elischer (julian@tfs.com) Sept 1992
+ *
+ * Mach Operating System
+ * Copyright (c) 1992, 1991 Carnegie Mellon University
+ * All Rights Reserved.
+ * 
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ * 
+ * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
+ * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
+ * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ * 
+ * Carnegie Mellon requests users of this software to return to
+ * 
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ * 
+ * any improvements or extensions that they make and grant Carnegie Mellon
+ * the rights to redistribute these changes.
+ */
+
+#include <sys/types.h>
+#include <machine/pio.h>
+#include <stand.h>
+
+#define K_RDWR 		0x60		/* keyboard data & cmds (read/write) */
+#define K_STATUS 	0x64		/* keyboard status */
+#define K_CMD	 	0x64		/* keybd ctlr command (write-only) */
+
+#define K_OBUF_FUL 	0x01		/* output buffer full */
+#define K_IBUF_FUL 	0x02		/* input buffer full */
+
+#define KC_CMD_WIN	0xd0		/* read  output port */
+#define KC_CMD_WOUT	0xd1		/* write output port */
+#define KB_A20		0xdf		/* enable A20,
+					   enable output buffer full interrupt
+					   enable data line
+					   enable clock line */
+
+/*
+ * Gate A20 for high memory
+ */
+void
+gateA20(on)
+	int on;
+{
+#ifdef	IBM_L40
+	outb(0x92, 0x2);
+#else	IBM_L40
+	while (inb(K_STATUS) & K_IBUF_FUL);
+
+	while (inb(K_STATUS) & K_OBUF_FUL)
+		(void)inb(K_RDWR);
+
+	outb(K_CMD, KC_CMD_WOUT);
+	while (inb(K_STATUS) & K_IBUF_FUL);
+
+	if (on)
+		outb(K_RDWR, KB_A20);
+	else
+		outb(K_RDWR, 0xcd);
+	while (inb(K_STATUS) & K_IBUF_FUL);
+
+	while (inb(K_STATUS) & K_OBUF_FUL)
+		(void)inb(K_RDWR);
+#endif	IBM_L40
+}