1 files changed, 112 insertions, 0 deletions
diff --git a/arch/x86/boot/tty.c b/arch/x86/boot/tty.c
new file mode 100644
index 000000000000..f3f14bd26371
--- /dev/null
+++ b/arch/x86/boot/tty.c
@@ -0,0 +1,112 @@
+/* -*- linux-c -*- ------------------------------------------------------- *
+ *
+ *   Copyright (C) 1991, 1992 Linus Torvalds
+ *   Copyright 2007 rPath, Inc. - All Rights Reserved
+ *
+ *   This file is part of the Linux kernel, and is made available under
+ *   the terms of the GNU General Public License version 2.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * arch/i386/boot/tty.c
+ *
+ * Very simple screen I/O
+ * XXX: Probably should add very simple serial I/O?
+ */
+
+#include "boot.h"
+
+/*
+ * These functions are in .inittext so they can be used to signal
+ * error during initialization.
+ */
+
+void __attribute__((section(".inittext"))) putchar(int ch)
+{
+	unsigned char c = ch;
+
+	if (c == '\n')
+		putchar('\r');	/* \n -> \r\n */
+
+	/* int $0x10 is known to have bugs involving touching registers
+	   it shouldn't.  Be extra conservative... */
+	asm volatile("pushal; pushw %%ds; int $0x10; popw %%ds; popal"
+		     : : "b" (0x0007), "c" (0x0001), "a" (0x0e00|ch));
+}
+
+void __attribute__((section(".inittext"))) puts(const char *str)
+{
+	int n = 0;
+	while (*str) {
+		putchar(*str++);
+		n++;
+	}
+}
+
+/*
+ * Read the CMOS clock through the BIOS, and return the
+ * seconds in BCD.
+ */
+
+static u8 gettime(void)
+{
+	u16 ax = 0x0200;
+	u16 cx, dx;
+
+	asm volatile("int $0x1a"
+		     : "+a" (ax), "=c" (cx), "=d" (dx)
+		     : : "ebx", "esi", "edi");
+
+	return dx >> 8;
+}
+
+/*
+ * Read from the keyboard
+ */
+int getchar(void)
+{
+	u16 ax = 0;
+	asm volatile("int $0x16" : "+a" (ax));
+
+	return ax & 0xff;
+}
+
+static int kbd_pending(void)
+{
+	u8 pending;
+	asm volatile("int $0x16; setnz %0"
+		     : "=rm" (pending)
+		     : "a" (0x0100));
+	return pending;
+}
+
+void kbd_flush(void)
+{
+	for (;;) {
+		if (!kbd_pending())
+			break;
+		getchar();
+	}
+}
+
+int getchar_timeout(void)
+{
+	int cnt = 30;
+	int t0, t1;
+
+	t0 = gettime();
+
+	while (cnt) {
+		if (kbd_pending())
+			return getchar();
+
+		t1 = gettime();
+		if (t0 != t1) {
+			cnt--;
+			t0 = t1;
+		}
+	}
+
+	return 0;		/* Timeout! */
+}