leds: pca963x: enable low-power state

Allow chip to enter low power state when no LEDs are being lit or in
blink mode.

Cc: Peter Meerwald <p.meerwald@bct-electronic.com>,
Cc: Ricardo Ribalda <ricardo.ribalda@gmail.com>
Cc: Tony Lindgren <tony@atomide.com>
Signed-off-by: Matt Ranostay <matt@ranostay.consulting>
Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>

drivers/leds/leds-pca963x.c

@@ -103,6 +103,7 @@ struct pca963x {
 	struct mutex mutex;
 	struct i2c_client *client;
 	struct pca963x_led *leds;
+	unsigned long leds_on;
 };
 
 struct pca963x_led {
@@ -124,7 +125,6 @@ static int pca963x_brightness(struct pca963x_led *pca963x,
 	u8 mask = 0x3 << shift;
 	int ret;
 
-	mutex_lock(&pca963x->chip->mutex);
 	ledout = i2c_smbus_read_byte_data(pca963x->chip->client, ledout_addr);
 	switch (brightness) {
 	case LED_FULL:
@@ -141,14 +141,13 @@ static int pca963x_brightness(struct pca963x_led *pca963x,
 			PCA963X_PWM_BASE + pca963x->led_num,
 			brightness);
 		if (ret < 0)
-			goto unlock;
+			return ret;
 		ret = i2c_smbus_write_byte_data(pca963x->chip->client,
 			ledout_addr,
 			(ledout & ~mask) | (PCA963X_LED_PWM << shift));
 		break;
 	}
-unlock:
-	mutex_unlock(&pca963x->chip->mutex);
+
 	return ret;
 }
 
@@ -180,14 +179,41 @@ static void pca963x_blink(struct pca963x_led *pca963x)
 	mutex_unlock(&pca963x->chip->mutex);
 }
 
+static int pca963x_power_state(struct pca963x_led *pca963x)
+{
+	unsigned long *leds_on = &pca963x->chip->leds_on;
+	unsigned long cached_leds = pca963x->chip->leds_on;
+
+	if (pca963x->led_cdev.brightness)
+		set_bit(pca963x->led_num, leds_on);
+	else
+		clear_bit(pca963x->led_num, leds_on);
+
+	if (!(*leds_on) != !cached_leds)
+		return i2c_smbus_write_byte_data(pca963x->chip->client,
+			PCA963X_MODE1, *leds_on ? 0 : BIT(4));
+
+	return 0;
+}
+
 static int pca963x_led_set(struct led_classdev *led_cdev,
 	enum led_brightness value)
 {
 	struct pca963x_led *pca963x;
+	int ret;
 
 	pca963x = container_of(led_cdev, struct pca963x_led, led_cdev);
 
-	return pca963x_brightness(pca963x, value);
+	mutex_lock(&pca963x->chip->mutex);
+
+	ret = pca963x_brightness(pca963x, value);
+	if (ret < 0)
+		goto unlock;
+	ret = pca963x_power_state(pca963x);
+
+unlock:
+	mutex_unlock(&pca963x->chip->mutex);
+	return ret;
 }
 
 static unsigned int pca963x_period_scale(struct pca963x_led *pca963x,
@@ -403,8 +429,8 @@ static int pca963x_probe(struct i2c_client *client,
 			goto exit;
 	}
 
-	/* Disable LED all-call address and set normal mode */
-	i2c_smbus_write_byte_data(client, PCA963X_MODE1, 0x00);
+	/* Disable LED all-call address, and power down initially */
+	i2c_smbus_write_byte_data(client, PCA963X_MODE1, BIT(4));
 
 	if (pdata) {
 		/* Configure output: open-drain or totem pole (push-pull) */