backlight: gpio_backlight: Convert to use GPIO descriptor

This driver is predominantly used by device tree systems, all
of which can deal with modern GPIO descriptors. The legacy
GPIO API is only used by one SH board so make the GPIO
descriptor the default way to deal with it.

As an intended side effect we do not need to look around in
the device tree for the inversion flag since the GPIO
descriptors will intrinsically deal with this.
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>
Acked-by: NDaniel Thompson <daniel.thompson@linaro.org>
Reviewed-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NLee Jones <lee.jones@linaro.org>

drivers/video/backlight/gpio_backlight.c

@@ -9,7 +9,8 @@
 #include <linux/backlight.h>
 #include <linux/err.h>
 #include <linux/fb.h>
-#include <linux/gpio.h>
+#include <linux/gpio.h> /* Only for legacy support */
+#include <linux/gpio/consumer.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
@@ -23,7 +24,7 @@ struct gpio_backlight {
 	struct device *dev;
 	struct device *fbdev;
 
-	int gpio;
+	struct gpio_desc *gpiod;
 	int active;
 	int def_value;
 };
@@ -38,8 +39,8 @@ static int gpio_backlight_update_status(struct backlight_device *bl)
 	    bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
 		brightness = 0;
 
-	gpio_set_value_cansleep(gbl->gpio,
-				brightness ? gbl->active : !gbl->active);
+	gpiod_set_value_cansleep(gbl->gpiod,
+				 brightness ? gbl->active : !gbl->active);
 
 	return 0;
 }
@@ -61,23 +62,27 @@ static const struct backlight_ops gpio_backlight_ops = {
 static int gpio_backlight_probe_dt(struct platform_device *pdev,
 				   struct gpio_backlight *gbl)
 {
-	struct device_node *np = pdev->dev.of_node;
-	enum of_gpio_flags gpio_flags;
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+	enum gpiod_flags flags;
+	int ret;
+
+	gbl->def_value = of_property_read_bool(np, "default-on");
+	flags = gbl->def_value ? GPIOD_OUT_HIGH : GPIOD_OUT_LOW;
+	/* GPIO descriptors keep track of inversion */
+	gbl->active = 1;
 
-	gbl->gpio = of_get_gpio_flags(np, 0, &gpio_flags);
+	gbl->gpiod = devm_gpiod_get(dev, NULL, flags);
+	if (IS_ERR(gbl->gpiod)) {
+		ret = PTR_ERR(gbl->gpiod);
 
-	if (!gpio_is_valid(gbl->gpio)) {
-		if (gbl->gpio != -EPROBE_DEFER) {
-			dev_err(&pdev->dev,
+		if (ret != -EPROBE_DEFER) {
+			dev_err(dev,
 				"Error: The gpios parameter is missing or invalid.\n");
 		}
-		return gbl->gpio;
+		return ret;
 	}
 
-	gbl->active = (gpio_flags & OF_GPIO_ACTIVE_LOW) ? 0 : 1;
-
-	gbl->def_value = of_property_read_bool(np, "default-on");
-
 	return 0;
 }
 
@@ -89,7 +94,6 @@ static int gpio_backlight_probe(struct platform_device *pdev)
 	struct backlight_device *bl;
 	struct gpio_backlight *gbl;
 	struct device_node *np = pdev->dev.of_node;
-	unsigned long flags = GPIOF_DIR_OUT;
 	int ret;
 
 	if (!pdata && !np) {
@@ -109,22 +113,33 @@ static int gpio_backlight_probe(struct platform_device *pdev)
 		if (ret)
 			return ret;
 	} else {
+		/*
+		 * Legacy platform data GPIO retrieveal. Do not expand
+		 * the use of this code path, currently only used by one
+		 * SH board.
+		 */
+		unsigned long flags = GPIOF_DIR_OUT;
+
 		gbl->fbdev = pdata->fbdev;
-		gbl->gpio = pdata->gpio;
 		gbl->active = pdata->active_low ? 0 : 1;
 		gbl->def_value = pdata->def_value;
-	}
-
-	if (gbl->active)
-		flags |= gbl->def_value ? GPIOF_INIT_HIGH : GPIOF_INIT_LOW;
-	else
-		flags |= gbl->def_value ? GPIOF_INIT_LOW : GPIOF_INIT_HIGH;
 
-	ret = devm_gpio_request_one(gbl->dev, gbl->gpio, flags,
-				    pdata ? pdata->name : "backlight");
-	if (ret < 0) {
-		dev_err(&pdev->dev, "unable to request GPIO\n");
-		return ret;
+		if (gbl->active)
+			flags |= gbl->def_value ?
+				GPIOF_INIT_HIGH : GPIOF_INIT_LOW;
+		else
+			flags |= gbl->def_value ?
+				GPIOF_INIT_LOW : GPIOF_INIT_HIGH;
+
+		ret = devm_gpio_request_one(gbl->dev, pdata->gpio, flags,
+					    pdata ? pdata->name : "backlight");
+		if (ret < 0) {
+			dev_err(&pdev->dev, "unable to request GPIO\n");
+			return ret;
+		}
+		gbl->gpiod = gpio_to_desc(pdata->gpio);
+		if (!gbl->gpiod)
+			return -EINVAL;
 	}
 
 	memset(&props, 0, sizeof(props));