sandbox: add a sandbox timer and basic test

Add a sandbox timer which get time from host os and a basic
test.

Signed-off-by: Thomas Chou <thomas@wytron.com.tw>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/timer/Kconfig b/drivers/timer/Kconfig
index 97c4128..601e493 100644
--- a/drivers/timer/Kconfig
+++ b/drivers/timer/Kconfig
@@ -16,4 +16,11 @@
 	  Select this to enable an timer for Altera devices. Please find
 	  details on the "Embedded Peripherals IP User Guide" of Altera.
 
+config SANDBOX_TIMER
+	bool "Sandbox Timer support"
+	depends on SANDBOX && TIMER
+	help
+	  Select this to enable an emulated timer for sandbox. It gets
+	  time from host os.
+
 endmenu
diff --git a/drivers/timer/Makefile b/drivers/timer/Makefile
index ae66c07..300946e 100644
--- a/drivers/timer/Makefile
+++ b/drivers/timer/Makefile
@@ -6,3 +6,4 @@
 
 obj-$(CONFIG_TIMER)		+= timer-uclass.o
 obj-$(CONFIG_ALTERA_TIMER)	+= altera_timer.o
+obj-$(CONFIG_SANDBOX_TIMER)	+= sandbox_timer.o
diff --git a/drivers/timer/sandbox_timer.c b/drivers/timer/sandbox_timer.c
new file mode 100644
index 0000000..38de763
--- /dev/null
+++ b/drivers/timer/sandbox_timer.c
@@ -0,0 +1,53 @@
+/*
+ * Copyright (C) 2015 Thomas Chou <thomas@wytron.com.tw>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <timer.h>
+#include <os.h>
+
+/* system timer offset in ms */
+static unsigned long sandbox_timer_offset;
+
+void sandbox_timer_add_offset(unsigned long offset)
+{
+	sandbox_timer_offset += offset;
+}
+
+static int sandbox_timer_get_count(struct udevice *dev, unsigned long *count)
+{
+	*count = os_get_nsec() / 1000 + sandbox_timer_offset * 1000;
+
+	return 0;
+}
+
+static int sandbox_timer_probe(struct udevice *dev)
+{
+	struct timer_dev_priv *uc_priv = dev_get_uclass_priv(dev);
+
+	uc_priv->clock_rate = 1000000;
+
+	return 0;
+}
+
+static const struct timer_ops sandbox_timer_ops = {
+	.get_count = sandbox_timer_get_count,
+};
+
+static const struct udevice_id sandbox_timer_ids[] = {
+	{ .compatible = "sandbox,timer" },
+	{ }
+};
+
+U_BOOT_DRIVER(sandbox_timer) = {
+	.name	= "sandbox_timer",
+	.id	= UCLASS_TIMER,
+	.of_match = sandbox_timer_ids,
+	.probe = sandbox_timer_probe,
+	.ops	= &sandbox_timer_ops,
+	.flags = DM_FLAG_PRE_RELOC,
+};