2 files changed, 55 insertions, 7 deletions

diff --git a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
index 1e4fc727f3b1..72810cc2dbc1 100644
--- a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
+++ b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
@@ -14,8 +14,11 @@ Required properties:
 Optional properties:
   - pwm-names: a list of names for the PWM devices specified in the
                "pwms" property (see PWM binding[0])
+  - enable-gpios: contains a single GPIO specifier for the GPIO which enables
+                  and disables the backlight (see GPIO binding[1])
 
 [0]: Documentation/devicetree/bindings/pwm/pwm.txt
+[1]: Documentation/devicetree/bindings/gpio/gpio.txt
 
 Example:
 
@@ -25,4 +28,6 @@ Example:
 
                 brightness-levels = <0 4 8 16 32 64 128 255>;
                 default-brightness-level = <6>;
+
+                enable-gpios = <&gpio 58 0>;
         };
diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index 51a802fff50d..18b885497289 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -10,6 +10,8 @@
  * published by the Free Software Foundation.
  */
 
+#include <linux/gpio.h>
+#include <linux/of_gpio.h>
 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/init.h>
@@ -28,6 +30,8 @@ struct pwm_bl_data {
         unsigned int            lth_brightness;
         unsigned int            *levels;
         bool                    enabled;
+        int                     enable_gpio;
+        unsigned long           enable_gpio_flags;
         int                     (*notify)(struct device *,
                                           int brightness);
         void                    (*notify_after)(struct device *,
@@ -56,6 +60,14 @@ static void pwm_backlight_power_on(struct pwm_bl_data *pb, int brightness,
                      pb->lth_brightness;
 
         pwm_config(pb->pwm, duty_cycle, pb->period);
+
+        if (gpio_is_valid(pb->enable_gpio)) {
+                if (pb->enable_gpio_flags & PWM_BACKLIGHT_GPIO_ACTIVE_LOW)
+                        gpio_set_value(pb->enable_gpio, 0);
+                else
+                        gpio_set_value(pb->enable_gpio, 1);
+        }
+
         pwm_enable(pb->pwm);
         pb->enabled = true;
 }
@@ -68,6 +80,13 @@ static void pwm_backlight_power_off(struct pwm_bl_data *pb)
         pwm_config(pb->pwm, 0, pb->period);
         pwm_disable(pb->pwm);
 
+        if (gpio_is_valid(pb->enable_gpio)) {
+                if (pb->enable_gpio_flags & PWM_BACKLIGHT_GPIO_ACTIVE_LOW)
+                        gpio_set_value(pb->enable_gpio, 1);
+                else
+                        gpio_set_value(pb->enable_gpio, 0);
+        }
+
         pb->enabled = false;
 }
 
@@ -120,6 +139,7 @@ static int pwm_backlight_parse_dt(struct device *dev,
                                   struct platform_pwm_backlight_data *data)
 {
         struct device_node *node = dev->of_node;
+        enum of_gpio_flags flags;
         struct property *prop;
         int length;
         u32 value;
@@ -160,11 +180,13 @@ 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.
-         */
+        data->enable_gpio = of_get_named_gpio_flags(node, "enable-gpios", 0,
+                                                    &flags);
+        if (data->enable_gpio == -EPROBE_DEFER)
+                return -EPROBE_DEFER;
+
+        if (gpio_is_valid(data->enable_gpio) && (flags & OF_GPIO_ACTIVE_LOW))
+                data->enable_gpio_flags |= PWM_BACKLIGHT_GPIO_ACTIVE_LOW;
 
         return 0;
 }
@@ -252,6 +274,8 @@ static int pwm_backlight_probe(struct platform_device *pdev)
         } else
                 max = data->max_brightness;
 
+        pb->enable_gpio = data->enable_gpio;
+        pb->enable_gpio_flags = data->enable_gpio_flags;
         pb->notify = data->notify;
         pb->notify_after = data->notify_after;
         pb->check_fb = np ? pwm_backlight_check_fb_dt : data->check_fb;
@@ -259,6 +283,22 @@ static int pwm_backlight_probe(struct platform_device *pdev)
         pb->dev = &pdev->dev;
         pb->enabled = false;
 
+        if (gpio_is_valid(pb->enable_gpio)) {
+                unsigned long flags;
+
+                if (pb->enable_gpio_flags & PWM_BACKLIGHT_GPIO_ACTIVE_LOW)
+                        flags = GPIOF_OUT_INIT_HIGH;
+                else
+                        flags = GPIOF_OUT_INIT_LOW;
+
+                ret = gpio_request_one(pb->enable_gpio, flags, "enable");
+                if (ret < 0) {
+                        dev_err(&pdev->dev, "failed to request GPIO#%d: %d\n",
+                                pb->enable_gpio, ret);
+                        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");
@@ -267,7 +307,7 @@ static int pwm_backlight_probe(struct platform_device *pdev)
                 if (IS_ERR(pb->pwm)) {
                         dev_err(&pdev->dev, "unable to request legacy PWM\n");
                         ret = PTR_ERR(pb->pwm);
-                        goto err_alloc;
+                        goto err_gpio;
                 }
         }
 
@@ -292,7 +332,7 @@ static int pwm_backlight_probe(struct platform_device *pdev)
         if (IS_ERR(bl)) {
                 dev_err(&pdev->dev, "failed to register backlight\n");
                 ret = PTR_ERR(bl);
-                goto err_alloc;
+                goto err_gpio;
         }
 
         if (data->dft_brightness > data->max_brightness) {
@@ -308,6 +348,9 @@ static int pwm_backlight_probe(struct platform_device *pdev)
         platform_set_drvdata(pdev, bl);
         return 0;
 
+err_gpio:
+        if (gpio_is_valid(pb->enable_gpio))
+                gpio_free(pb->enable_gpio);
 err_alloc:
         if (data->exit)
                 data->exit(&pdev->dev);