sandbox: Add serial uart

This uart simply writes to stdout and reads from stdin. We might imagine
instead buffering the data so that a test interface can check output and
inject input.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/serial/sandbox.c b/drivers/serial/sandbox.c
new file mode 100644
index 0000000..0d65587
--- /dev/null
+++ b/drivers/serial/sandbox.c
@@ -0,0 +1,63 @@
+/*
+ * Copyright (c) 2011 The Chromium OS Authors.
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+/*
+ * This provide a test serial port. It provides an emulated serial port where
+ * a test program and read out the serial output and inject serial input for
+ * U-Boot.
+ */
+
+#include <common.h>
+#include <os.h>
+
+int serial_init(void)
+{
+	return 0;
+}
+
+void serial_setbrg(void)
+{
+}
+
+void serial_putc(const char ch)
+{
+	os_write(1, &ch, 1);
+}
+
+void serial_puts(const char *str)
+{
+	while (*str)
+		serial_putc(*str++);
+}
+
+int serial_getc(void)
+{
+	char buf;
+	int count;
+
+	count = os_read(0, &buf, 1);
+	return count == 1 ? buf : 0;
+}
+
+int serial_tstc(void)
+{
+	return 0;
+}