dm: led: Add support for getting the state of an LED

It is useful to be able to read the LED as well as write it. Add this to
the uclass and update the GPIO driver.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Ziping Chen <techping.chan@gmail.com>

drivers/led/led-uclass.c

@@ -42,6 +42,16 @@ int led_set_state(struct udevice *dev, enum led_state_t state)
 	return ops->set_state(dev, state);
 }
 
+enum led_state_t led_get_state(struct udevice *dev)
+{
+	struct led_ops *ops = led_get_ops(dev);
+
+	if (!ops->get_state)
+		return -ENOSYS;
+
+	return ops->get_state(dev);
+}
+
 UCLASS_DRIVER(led) = {
 	.id		= UCLASS_LED,
 	.name		= "led",

drivers/led/led_gpio.c

@@ -24,10 +24,31 @@ static int gpio_led_set_state(struct udevice *dev, enum led_state_t state)
 
 	if (!dm_gpio_is_valid(&priv->gpio))
 		return -EREMOTEIO;
+	switch (state) {
+	case LEDST_OFF:
+	case LEDST_ON:
+		break;
+	default:
+		return -ENOSYS;
+	}
 
 	return dm_gpio_set_value(&priv->gpio, state);
 }
 
+static enum led_state_t gpio_led_get_state(struct udevice *dev)
+{
+	struct led_gpio_priv *priv = dev_get_priv(dev);
+	int ret;
+
+	if (!dm_gpio_is_valid(&priv->gpio))
+		return -EREMOTEIO;
+	ret = dm_gpio_get_value(&priv->gpio);
+	if (ret < 0)
+		return ret;
+
+	return ret ? LEDST_ON : LEDST_OFF;
+}
+
 static int led_gpio_probe(struct udevice *dev)
 {
 	struct led_uc_plat *uc_plat = dev_get_uclass_platdata(dev);
@@ -88,6 +109,7 @@ static int led_gpio_bind(struct udevice *parent)
 
 static const struct led_ops gpio_led_ops = {
 	.set_state	= gpio_led_set_state,
+	.get_state	= gpio_led_get_state,
 };
 
 static const struct udevice_id led_gpio_ids[] = {

include/led.h

@@ -33,6 +33,14 @@ struct led_ops {
 	 * @return 0 if OK, -ve on error
 	 */
 	int (*set_state)(struct udevice *dev, enum led_state_t state);
+
+	/**
+	 * led_get_state() - get the state of an LED
+	 *
+	 * @dev:	LED device to change
+	 * @return LED state led_state_t, or -ve on error
+	 */
+	enum led_state_t (*get_state)(struct udevice *dev);
 };
 
 #define led_get_ops(dev)	((struct led_ops *)(dev)->driver->ops)
@@ -55,4 +63,12 @@ int led_get_by_label(const char *label, struct udevice **devp);
  */
 int led_set_state(struct udevice *dev, enum led_state_t state);
 
+/**
+ * led_get_state() - get the state of an LED
+ *
+ * @dev:	LED device to change
+ * @return LED state led_state_t, or -ve on error
+ */
+enum led_state_t led_get_state(struct udevice *dev);
+
 #endif

test/dm/led.c

@@ -43,9 +43,11 @@ static int dm_test_led_gpio(struct unit_test_state *uts)
 	ut_asserteq(0, sandbox_gpio_get_value(gpio, offset));
 	ut_assertok(led_set_state(dev, LEDST_ON));
 	ut_asserteq(1, sandbox_gpio_get_value(gpio, offset));
+	ut_asserteq(LEDST_ON, led_get_state(dev));
 
 	ut_assertok(led_set_state(dev, LEDST_OFF));
 	ut_asserteq(0, sandbox_gpio_get_value(gpio, offset));
+	ut_asserteq(LEDST_OFF, led_get_state(dev));
 
 	return 0;
 }