i386: fix machine rebooting

Commit 59f4e7d572980a521b7bdba74ab71b21f5995538 fixed machine rebooting
on Truxton's machine (when no keyboard was present).  But it broke it on
Lee's machine.

The patch reinstates the old (pre-59f4e7d572980a521b7bdba74ab71b21f5995538)
code and if that doesn't work out, try the new,
post-59f4e7d572980a521b7bdba74ab71b21f5995538 code instead.

Cc: Lee Garrett <lee-in-berlin@web.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/asm-i386/mach-default/mach_reboot.h

@@ -19,14 +19,37 @@ static inline void kb_wait(void)
 static inline void mach_reboot(void)
 {
 	int i;
+
+	/* old method, works on most machines */
 	for (i = 0; i < 10; i++) {
+		kb_wait();
+		udelay(50);
+		outb(0xfe, 0x64);	/* pulse reset low */
+		udelay(50);
+	}
+
+	/* New method: sets the "System flag" which, when set, indicates
+	 * successful completion of the keyboard controller self-test (Basic
+	 * Assurance Test, BAT).  This is needed for some machines with no
+	 * keyboard plugged in.  This read-modify-write sequence sets only the
+	 * system flag
+	 */
+	for (i = 0; i < 10; i++) {
+		int cmd;
+
+		outb(0x20, 0x64);	/* read Controller Command Byte */
+		udelay(50);
+		kb_wait();
+		udelay(50);
+		cmd = inb(0x60);
+		udelay(50);
 		kb_wait();
 		udelay(50);
 		outb(0x60, 0x64);	/* write Controller Command Byte */
 		udelay(50);
 		kb_wait();
 		udelay(50);
-		outb(0x14, 0x60);	/* set "System flag" */
+		outb(cmd | 0x04, 0x60);	/* set "System flag" */
 		udelay(50);
 		kb_wait();
 		udelay(50);