backlight: lp855x: Add supply regulator to lp855x

This patch adds a supply regulator to the lp855x platform data to facilitate
powering on/off the 3V rail attached to the controller.

Cc: Stéphane Marchesin <marcheu@chromium.org>
Cc: Aaron Durbin <adurbin@chromium.org>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Acked-by: Milo Kim <milo.kim@ti.com>
Acked-by: Bryan Wu <cooloney@gmail.com>
Acked-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

Documentation/devicetree/bindings/video/backlight/lp855x.txt

@@ -12,6 +12,7 @@ Optional properties:
   - pwm-period: PWM period value. Set only PWM input mode used (u32)
   - rom-addr: Register address of ROM area to be updated (u8)
   - rom-val: Register value to be updated (u8)
+  - power-supply: Regulator which controls the 3V rail
 
 Example:
 
@@ -56,6 +57,7 @@ Example:
 	backlight@2c {
 		compatible = "ti,lp8557";
 		reg = <0x2c>;
+		power-supply = <&backlight_vdd>;
 
 		dev-ctrl = /bits/ 8 <0x41>;
 		init-brt = /bits/ 8 <0x0a>;

drivers/video/backlight/lp855x_bl.c

@@ -17,6 +17,7 @@
 #include <linux/of.h>
 #include <linux/platform_data/lp855x.h>
 #include <linux/pwm.h>
+#include <linux/regulator/consumer.h>
 
 /* LP8550/1/2/3/6 Registers */
 #define LP855X_BRIGHTNESS_CTRL		0x00
@@ -383,6 +384,13 @@ static int lp855x_parse_dt(struct lp855x *lp)
 		pdata->rom_data = &rom[0];
 	}
 
+	pdata->supply = devm_regulator_get(dev, "power");
+	if (IS_ERR(pdata->supply)) {
+		if (PTR_ERR(pdata->supply) == -EPROBE_DEFER)
+			return -EPROBE_DEFER;
+		pdata->supply = NULL;
+	}
+
 	lp->pdata = pdata;
 
 	return 0;
@@ -423,6 +431,14 @@ static int lp855x_probe(struct i2c_client *cl, const struct i2c_device_id *id)
 	else
 		lp->mode = REGISTER_BASED;
 
+	if (lp->pdata->supply) {
+		ret = regulator_enable(lp->pdata->supply);
+		if (ret < 0) {
+			dev_err(&cl->dev, "failed to enable supply: %d\n", ret);
+			return ret;
+		}
+	}
+
 	i2c_set_clientdata(cl, lp);
 
 	ret = lp855x_configure(lp);
@@ -454,6 +470,8 @@ static int lp855x_remove(struct i2c_client *cl)
 
 	lp->bl->props.brightness = 0;
 	backlight_update_status(lp->bl);
+	if (lp->pdata->supply)
+		regulator_disable(lp->pdata->supply);
 	sysfs_remove_group(&lp->dev->kobj, &lp855x_attr_group);
 
 	return 0;

include/linux/platform_data/lp855x.h

@@ -136,6 +136,7 @@ struct lp855x_rom_data {
 		Only valid when mode is PWM_BASED.
  * @size_program : total size of lp855x_rom_data
  * @rom_data : list of new eeprom/eprom registers
+ * @supply : regulator that supplies 3V input
  */
 struct lp855x_platform_data {
 	const char *name;
@@ -144,6 +145,7 @@ struct lp855x_platform_data {
 	unsigned int period_ns;
 	int size_program;
 	struct lp855x_rom_data *rom_data;
+	struct regulator *supply;
 };
 
 #endif