pwm-backlight: Use new enable_gpio field

Make use of the new enable_gpio field and allow it to be set from DT as
well. Now that all legacy users of platform data have been converted to
initialize this field to an invalid value, it is safe to use the field
from the driver.

Signed-off-by: Thierry Reding <treding@nvidia.com>
(cherry picked from commit 8265b2e4e62632b01f998095d1bbda4d281629fe)

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);