[PATCHv8] video: backlight: gpio-backlight: Add DT support.

[PATCHv8] video: backlight: gpio-backlight: Add DT support.

[Denis Carikli]

Cc: Richard Purdie <rpurdie-Fm38FmjxZ/leoWH0uzbU5w@public.gmane.org>
Cc: Jingoo Han <jg1.han-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
Cc: Laurent Pinchart <laurent.pinchart-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org>
Cc: Rob Herring <rob.herring-bsGFqQB8/DxBDgjK7y7TUQ@public.gmane.org>
Cc: Pawel Moll <pawel.moll-5wv7dgnIgG8@public.gmane.org>
Cc: Mark Rutland <mark.rutland-5wv7dgnIgG8@public.gmane.org>
Cc: Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
Cc: Ian Campbell <ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg@public.gmane.org>
Cc: devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Cc: Sascha Hauer <kernel-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
Cc: linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
Cc: Lothar Waßmann <LW-bxm8fMRDkQLDiMYJYoSAnRvVK+yQ3ZXh@public.gmane.org>
Cc: Jean-Christophe Plagniol-Villard <plagnioj-sclMFOaUSTBWk0Htik3J/w@public.gmane.org>
Cc: Thierry Reding <thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: Eric Bénard <eric-fO0SIAKYzcbQT0dZR+AlfA@public.gmane.org>
Signed-off-by: Denis Carikli <denis-fO0SIAKYzcbQT0dZR+AlfA@public.gmane.org>
---
ChangeLog v7->v8:
- The default-state was renamed to default-brightness-level.
- default-brightness-level is now mandatory, like for backlight-pwm,
  That way we avoid having to handle the case where it's not set,
  which means that we would need not to set the gpio, but still
  report a brightness value for sysfs, when not all gpio controllers are
  able to read the gpio value.
- switched the default-brightness-level to boolean values (0 or 1) instead
  of using strings ("on", "off", "keep").
- The documentation was updated accordingly.
- The example in the documentation now uses the dts gpio defines.
- The "backlight: gpio_backlight: Use a default state enum." patch was then
  dropped, becuase it is not necessary anymore.

ChangeLog v6->v7:
- removed a compilation warning with the removal of the useless ret declaration.

ChangeLog v5->v6:
- The default state handling was reworked:
  - it's now called default-state, and looks like the gpio-leds default-state.
  - it now has a "keep" option, like for the gpio-leds.
  - that "keep" option is the default when the default-state property is not set.
- The documentation was updated accordingly.

ChangeLog v4->v5:
- The default-brightness property now defaults to 0 in the driver.
- def_value int becomes a bool.
- The check for the gpio validity has been reworked.
---
 .../bindings/video/backlight/gpio-backlight.txt    |   19 ++++++
 drivers/video/backlight/gpio_backlight.c           |   64 +++++++++++++++++---
 2 files changed, 76 insertions(+), 7 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/video/backlight/gpio-backlight.txt

diff --git a/Documentation/devicetree/bindings/video/backlight/gpio-backlight.txt b/Documentation/devicetree/bindings/video/backlight/gpio-backlight.txt
new file mode 100644
index 0000000..d022add
--- /dev/null
+++ b/Documentation/devicetree/bindings/video/backlight/gpio-backlight.txt
@@ -0,0 +1,19 @@
+gpio-backlight bindings
+
+Required properties:
+  - compatible: "gpio-backlight"
+  - gpios: describes the gpio that is used for enabling/disabling the backlight
+    (see GPIO binding[0] for more details).
+  - default-brightness-level: the default brightness level. Valid values:
+    - 0: off
+    - 1: on
+
+[0]: Documentation/devicetree/bindings/gpio/gpio.txt
+
+Example:
+
+	backlight {
+		compatible = "gpio-backlight";
+		gpios = <&gpio3 4 GPIO_ACTIVE_HIGH>;
+		default-brightness-level = <1>;
+	};
diff --git a/drivers/video/backlight/gpio_backlight.c b/drivers/video/backlight/gpio_backlight.c
index 81fb127..829a5dd 100644
--- a/drivers/video/backlight/gpio_backlight.c
+++ b/drivers/video/backlight/gpio_backlight.c
@@ -13,6 +13,8 @@
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_gpio.h>
 #include <linux/platform_data/gpio_backlight.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
@@ -23,6 +25,7 @@ struct gpio_backlight {
 
 	int gpio;
 	int active;
+	int def_value;
 };
 
 static int gpio_backlight_update_status(struct backlight_device *bl)
@@ -60,6 +63,37 @@ static const struct backlight_ops gpio_backlight_ops = {
 	.check_fb	= gpio_backlight_check_fb,
 };
 
+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;
+	int ret;
+
+	gbl->fbdev = NULL;
+	gbl->gpio = of_get_gpio_flags(np, 0, &gpio_flags);
+
+	if (!gpio_is_valid(gbl->gpio)) {
+		if (gbl->gpio != -EPROBE_DEFER) {
+			dev_err(&pdev->dev,
+				"Error: The gpios parameter is missing or invalid.\n");
+		}
+		return gbl->gpio;
+	}
+
+	gbl->active = (gpio_flags & OF_GPIO_ACTIVE_LOW) ? 0 : 1;
+
+	ret = of_property_read_u32(np, "default-brightness-level",
+				   &gbl->def_value);
+	if (ret < 0) {
+		dev_err(&pdev->dev,
+			"Error: The default-brightness-level parameter is missing or invalid.\n");
+		return ret;
+	}
+
+	return 0;
+}
+
 static int gpio_backlight_probe(struct platform_device *pdev)
 {
 	struct gpio_backlight_platform_data *pdata =
@@ -67,10 +101,12 @@ static int gpio_backlight_probe(struct platform_device *pdev)
 	struct backlight_properties props;
 	struct backlight_device *bl;
 	struct gpio_backlight *gbl;
+	struct device_node *np = pdev->dev.of_node;
 	int ret;
 
-	if (!pdata) {
-		dev_err(&pdev->dev, "failed to find platform data\n");
+	if (!pdata && !np) {
+		dev_err(&pdev->dev,
+			"failed to find platform data or device tree node.\n");
 		return -ENODEV;
 	}
 
@@ -79,14 +115,22 @@ static int gpio_backlight_probe(struct platform_device *pdev)
 		return -ENOMEM;
 
 	gbl->dev = &pdev->dev;
-	gbl->fbdev = pdata->fbdev;
-	gbl->gpio = pdata->gpio;
-	gbl->active = pdata->active_low ? 0 : 1;
+
+	if (np) {
+		ret = gpio_backlight_probe_dt(pdev, gbl);
+		if (ret)
+			return ret;
+	} else {
+		gbl->fbdev = pdata->fbdev;
+		gbl->gpio = pdata->gpio;
+		gbl->active = pdata->active_low ? 0 : 1;
+		gbl->def_value = pdata->def_value;
+	}
 
 	ret = devm_gpio_request_one(gbl->dev, gbl->gpio, GPIOF_DIR_OUT |
 				    (gbl->active ? GPIOF_INIT_LOW
 						 : GPIOF_INIT_HIGH),
-				    pdata->name);
+				    pdata ? pdata->name : "backlight");
 	if (ret < 0) {
 		dev_err(&pdev->dev, "unable to request GPIO\n");
 		return ret;
@@ -103,17 +147,23 @@ static int gpio_backlight_probe(struct platform_device *pdev)
 		return PTR_ERR(bl);
 	}
 
-	bl->props.brightness = pdata->def_value;
+	bl->props.brightness = gbl->def_value;
 	backlight_update_status(bl);
 
 	platform_set_drvdata(pdev, bl);
 	return 0;
 }
 
+static struct of_device_id gpio_backlight_of_match[] = {
+	{ .compatible = "gpio-backlight" },
+	{ /* sentinel */ }
+};
+
 static struct platform_driver gpio_backlight_driver = {
 	.driver		= {
 		.name		= "gpio-backlight",
 		.owner		= THIS_MODULE,
+		.of_match_table = of_match_ptr(gpio_backlight_of_match),
 	},
 	.probe		= gpio_backlight_probe,
 };
-- 
1.7.9.5

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Re: [PATCHv8] video: backlight: gpio-backlight: Add DT support.

[Mark Rutland]

On Tue, Jan 07, 2014 at 10:02:53AM +0000, Denis Carikli wrote:
> Cc: Richard Purdie <rpurdie@rpsys.net>
> Cc: Jingoo Han <jg1.han@samsung.com>
> Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Cc: Rob Herring <rob.herring@calxeda.com>
> Cc: Pawel Moll <pawel.moll@arm.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Stephen Warren <swarren@wwwdotorg.org>
> Cc: Ian Campbell <ijc+devicetree@hellion.org.uk>
> Cc: devicetree@vger.kernel.org
> Cc: Sascha Hauer <kernel@pengutronix.de>
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: Lothar Waßmann <LW@KARO-electronics.de>
> Cc: Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>
> Cc: Thierry Reding <thierry.reding@gmail.com>
> Cc: Eric Bénard <eric@eukrea.com>
> Signed-off-by: Denis Carikli <denis@eukrea.com>
> ---
> ChangeLog v7->v8:
> - The default-state was renamed to default-brightness-level.
> - default-brightness-level is now mandatory, like for backlight-pwm,
>   That way we avoid having to handle the case where it's not set,
>   which means that we would need not to set the gpio, but still
>   report a brightness value for sysfs, when not all gpio controllers are
>   able to read the gpio value.
> - switched the default-brightness-level to boolean values (0 or 1) instead
>   of using strings ("on", "off", "keep").
> - The documentation was updated accordingly.
> - The example in the documentation now uses the dts gpio defines.
> - The "backlight: gpio_backlight: Use a default state enum." patch was then
>   dropped, becuase it is not necessary anymore.
> 
> ChangeLog v6->v7:
> - removed a compilation warning with the removal of the useless ret declaration.
> 
> ChangeLog v5->v6:
> - The default state handling was reworked:
>   - it's now called default-state, and looks like the gpio-leds default-state.
>   - it now has a "keep" option, like for the gpio-leds.
>   - that "keep" option is the default when the default-state property is not set.
> - The documentation was updated accordingly.
> 
> ChangeLog v4->v5:
> - The default-brightness property now defaults to 0 in the driver.
> - def_value int becomes a bool.
> - The check for the gpio validity has been reworked.
> ---
>  .../bindings/video/backlight/gpio-backlight.txt    |   19 ++++++
>  drivers/video/backlight/gpio_backlight.c           |   64 +++++++++++++++++---
>  2 files changed, 76 insertions(+), 7 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/video/backlight/gpio-backlight.txt
> 
> diff --git a/Documentation/devicetree/bindings/video/backlight/gpio-backlight.txt b/Documentation/devicetree/bindings/video/backlight/gpio-backlight.txt
> new file mode 100644
> index 0000000..d022add
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/video/backlight/gpio-backlight.txt
> @@ -0,0 +1,19 @@
> +gpio-backlight bindings
> +
> +Required properties:
> +  - compatible: "gpio-backlight"
> +  - gpios: describes the gpio that is used for enabling/disabling the backlight
> +    (see GPIO binding[0] for more details).
> +  - default-brightness-level: the default brightness level. Valid values:
> +    - 0: off
> +    - 1: on

If this is a boolean, use a boolean/empty property (default-on would be
a good candidate, or you could have default-off if most people are gonig
to want the display on at boot).

[...]

> +	ret = of_property_read_u32(np, "default-brightness-level",
> +				   &gbl->def_value);

This could be:

gbl->def_value = of_property_read_bool(np, "default-on");

Then you don't have to worry about people doing crazy things like having
default-brightness-level = <6> when you only support a boolean value.

Thanks,
Mark.
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