sandbox: timer: Support the early timer

Add support for the early timer so we can use tracing with sandbox again.

Signed-off-by: Simon Glass <sjg@chromium.org>

drivers/timer/sandbox_timer.c

@@ -10,6 +10,8 @@
 #include <timer.h>
 #include <os.h>
 
+#define SANDBOX_TIMER_RATE	1000000
+
 /* system timer offset in ms */
 static unsigned long sandbox_timer_offset;
 
@@ -18,9 +20,19 @@ void sandbox_timer_add_offset(unsigned long offset)
 	sandbox_timer_offset += offset;
 }
 
-static int sandbox_timer_get_count(struct udevice *dev, u64 *count)
+u64 notrace timer_early_get_count(void)
+{
+	return os_get_nsec() / 1000 + sandbox_timer_offset * 1000;
+}
+
+unsigned long notrace timer_early_get_rate(void)
+{
+	return SANDBOX_TIMER_RATE;
+}
+
+static notrace int sandbox_timer_get_count(struct udevice *dev, u64 *count)
 {
-	*count = os_get_nsec() / 1000 + sandbox_timer_offset * 1000;
+	*count = timer_early_get_count();
 
 	return 0;
 }
@@ -30,7 +42,7 @@ static int sandbox_timer_probe(struct udevice *dev)
 	struct timer_dev_priv *uc_priv = dev_get_uclass_priv(dev);
 
 	if (!uc_priv->clock_rate)
-		uc_priv->clock_rate = 1000000;
+		uc_priv->clock_rate = SANDBOX_TIMER_RATE;
 
 	return 0;
 }