[PATCH 1/1 v4] pwm_bl: Add support for backlight enable regulator

[Andrew Chew]

The backlight enable regulator is specified in the device tree node for
backlight.

Signed-off-by: Andrew Chew <achew@xxxxxxxxxx>
---
Changed the name of the property from en-supply to enable-supply.

Made enable-supply a mandatory property.  Changed the example in the
bindings documentation accordingly.

Moved devm_regulator_get() to the probe function.  Regulator is now
requested unconditionally.

Changed IS_ERR_OR_NULL to IS_ERR per Alex's recommendation.


 .../bindings/video/backlight/pwm-backlight.txt     |   14 ++++++
 drivers/video/backlight/pwm_bl.c                   |   52 ++++++++++++++++----
 2 files changed, 56 insertions(+), 10 deletions(-)

diff --git a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
index 1e4fc72..7e2e089 100644
--- a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
+++ b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
@@ -10,6 +10,11 @@ Required properties:
       last value in the array represents a 100% duty cycle (brightest).
   - default-brightness-level: the default brightness level (index into the
       array defined by the "brightness-levels" property)
+  - enable-supply: A phandle to the regulator device tree node. This
+      regulator will be turned on and off as the pwm is enabled and disabled.
+      Many backlights are enabled via a GPIO. In this case, we instantiate
+      a fixed regulator and give that to enable-supply. If a regulator
+      is not needed, then provide a dummy fixed regulator.
 
 Optional properties:
   - pwm-names: a list of names for the PWM devices specified in the
@@ -19,10 +24,19 @@ Optional properties:
 
 Example:
 
+	bl_en: fixed-regulator {
+                compatible = "regulator-fixed";
+                regulator-name = "bl-en-supply";
+                regulator-boot-on;
+                gpio = <&some_gpio>;
+                enable-active-high;
+	};
+
 	backlight {
 		compatible = "pwm-backlight";
 		pwms = <&pwm 0 5000000>;
 
 		brightness-levels = <0 4 8 16 32 64 128 255>;
 		default-brightness-level = <6>;
+		enable-supply = <&bl_en>;
 	};
diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index 069983c..ff98cdd 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -20,10 +20,13 @@
 #include <linux/pwm.h>
 #include <linux/pwm_backlight.h>
 #include <linux/slab.h>
+#include <linux/regulator/consumer.h>
 
 struct pwm_bl_data {
 	struct pwm_device	*pwm;
 	struct device		*dev;
+	struct regulator	*en_supply;
+	bool			en_supply_enabled;
 	unsigned int		period;
 	unsigned int		lth_brightness;
 	unsigned int		*levels;
@@ -35,6 +38,34 @@ struct pwm_bl_data {
 	void			(*exit)(struct device *);
 };
 
+static void pwm_backlight_enable(struct backlight_device *bl)
+{
+	struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
+
+	pwm_enable(pb->pwm);
+
+	if (pb->en_supply && !pb->en_supply_enabled) {
+		if (regulator_enable(pb->en_supply) != 0)
+			dev_warn(&bl->dev, "Failed to enable regulator");
+		else
+			pb->en_supply_enabled = true;
+	}
+}
+
+static void pwm_backlight_disable(struct backlight_device *bl)
+{
+	struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
+
+	if (pb->en_supply && pb->en_supply_enabled) {
+		if (regulator_disable(pb->en_supply) != 0)
+			dev_warn(&bl->dev, "Failed to disable regulator");
+		else
+			pb->en_supply_enabled = false;
+	}
+
+	pwm_disable(pb->pwm);
+}
+
 static int pwm_backlight_update_status(struct backlight_device *bl)
 {
 	struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
@@ -52,7 +83,7 @@ static int pwm_backlight_update_status(struct backlight_device *bl)
 
 	if (brightness == 0) {
 		pwm_config(pb->pwm, 0, pb->period);
-		pwm_disable(pb->pwm);
+		pwm_backlight_disable(bl);
 	} else {
 		int duty_cycle;
 
@@ -66,7 +97,7 @@ static int pwm_backlight_update_status(struct backlight_device *bl)
 		duty_cycle = pb->lth_brightness +
 		     (duty_cycle * (pb->period - pb->lth_brightness) / max);
 		pwm_config(pb->pwm, duty_cycle, pb->period);
-		pwm_enable(pb->pwm);
+		pwm_backlight_enable(bl);
 	}
 
 	if (pb->notify_after)
@@ -145,12 +176,6 @@ static int pwm_backlight_parse_dt(struct device *dev,
 		data->max_brightness--;
 	}
 
-	/*
-	 * TODO: Most users of this driver use a number of GPIOs to control
-	 *       backlight power. Support for specifying these needs to be
-	 *       added.
-	 */
-
 	return 0;
 }
 
@@ -213,6 +238,13 @@ static int pwm_backlight_probe(struct platform_device *pdev)
 	pb->exit = data->exit;
 	pb->dev = &pdev->dev;
 
+	pb->en_supply = devm_regulator_get(&pdev->dev, "enable");
+	if (IS_ERR(pb->en_supply)) {
+		ret = PTR_ERR(pb->en_supply);
+		pb->en_supply = NULL;
+		goto err_alloc;
+	}
+
 	pb->pwm = devm_pwm_get(&pdev->dev, NULL);
 	if (IS_ERR(pb->pwm)) {
 		dev_err(&pdev->dev, "unable to request PWM, trying legacy API\n");
@@ -268,7 +300,7 @@ static int pwm_backlight_remove(struct platform_device *pdev)
 
 	backlight_device_unregister(bl);
 	pwm_config(pb->pwm, 0, pb->period);
-	pwm_disable(pb->pwm);
+	pwm_backlight_disable(bl);
 	if (pb->exit)
 		pb->exit(&pdev->dev);
 	return 0;
@@ -283,7 +315,7 @@ static int pwm_backlight_suspend(struct device *dev)
 	if (pb->notify)
 		pb->notify(pb->dev, 0);
 	pwm_config(pb->pwm, 0, pb->period);
-	pwm_disable(pb->pwm);
+	pwm_backlight_disable(bl);
 	if (pb->notify_after)
 		pb->notify_after(pb->dev, 0);
 	return 0;
-- 
1.7.9.5

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