dm: led: Add support for blinking LEDs

Allow LEDs to be blinked if the driver supports it. Enable this for
sandbox so that the tests run.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Ziping Chen <techping.chan@gmail.com>
diff --git a/include/led.h b/include/led.h
index 8c107e2..c67af22 100644
--- a/include/led.h
+++ b/include/led.h
@@ -17,10 +17,22 @@
 	const char *label;
 };
 
+/**
+ * struct led_uc_priv - Private data the uclass stores about each device
+ *
+ * @period_ms:	Flash period in milliseconds
+ */
+struct led_uc_priv {
+	int period_ms;
+};
+
 enum led_state_t {
 	LEDST_OFF = 0,
 	LEDST_ON = 1,
 	LEDST_TOGGLE,
+#ifdef CONFIG_LED_BLINK
+	LEDST_BLINK,
+#endif
 
 	LEDST_COUNT,
 };
@@ -42,6 +54,20 @@
 	 * @return LED state led_state_t, or -ve on error
 	 */
 	enum led_state_t (*get_state)(struct udevice *dev);
+
+#ifdef CONFIG_LED_BLINK
+	/**
+	 * led_set_period() - set the blink period of an LED
+	 *
+	 * Thie records the period if supported, or returns -ENOSYS if not.
+	 * To start the LED blinking, use set_state().
+	 *
+	 * @dev:	LED device to change
+	 * @period_ms:	LED blink period in milliseconds
+	 * @return 0 if OK, -ve on error
+	 */
+	int (*set_period)(struct udevice *dev, int period_ms);
+#endif
 };
 
 #define led_get_ops(dev)	((struct led_ops *)(dev)->driver->ops)
@@ -72,4 +98,13 @@
  */
 enum led_state_t led_get_state(struct udevice *dev);
 
+/**
+ * led_set_period() - set the blink period of an LED
+ *
+ * @dev:	LED device to change
+ * @period_ms:	LED blink period in milliseconds
+ * @return 0 if OK, -ve on error
+ */
+int led_set_period(struct udevice *dev, int period_ms);
+
 #endif