1 files changed, 54 insertions, 0 deletions
diff --git a/sys/boot/i386/libi386/gatea20.c b/sys/boot/i386/libi386/gatea20.c
new file mode 100644
index 0000000..1c5f0f0
--- /dev/null
+++ b/sys/boot/i386/libi386/gatea20.c
@@ -0,0 +1,54 @@
+/*
+ * $NetBSD: gatea20.c,v 1.2 1997/10/29 00:32:49 fvdl Exp $
+ */
+
+/* extracted from freebsd:sys/i386/boot/biosboot/io.c */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <stand.h>
+#include <machine/cpufunc.h>
+
+#include <bootstrap.h>
+
+#include "libi386.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		0x9f		/* enable A20,
+					   reset (!),
+					   enable output buffer full interrupt
+					   enable data line
+					   disable clock line */
+
+/*
+ * Gate A20 for high memory
+ */
+static unsigned char	x_20 = KB_A20;
+void gateA20()
+{
+	__asm("pushfl ; cli");
+#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);
+	delay(100);
+	while (inb(K_STATUS) & K_IBUF_FUL);
+	outb(K_RDWR, x_20);
+	delay(100);
+	while (inb(K_STATUS) & K_IBUF_FUL);
+#endif	/* IBM_L40 */
+	__asm("popfl");
+}