[PATCH 1/5] backlight: Add GPIO-based backlight driver

[PATCH 1/5] backlight: Add GPIO-based backlight driver

[Laurent Pinchart]

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
 drivers/video/backlight/Kconfig          |    7 ++
 drivers/video/backlight/Makefile         |    1 +
 drivers/video/backlight/gpio_backlight.c |  158 ++++++++++++++++++++++++++++++
 include/video/gpio_backlight.h           |   21 ++++
 4 files changed, 187 insertions(+), 0 deletions(-)
 create mode 100644 drivers/video/backlight/gpio_backlight.c
 create mode 100644 include/video/gpio_backlight.h

diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index 765a945..259442d 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -390,6 +390,13 @@ config BACKLIGHT_TPS65217
 	  If you have a Texas Instruments TPS65217 say Y to enable the
 	  backlight driver.
 
+config BACKLIGHT_GPIO
+	tristate "Generic GPIO based Backlight Driver"
+	depends on GENERIC_GPIO
+	help
+	  If you have a LCD backlight adjustable by GPIO, say Y to enable
+	  this driver.
+
 endif # BACKLIGHT_CLASS_DEVICE
 
 endif # BACKLIGHT_LCD_SUPPORT
diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
index e7ce729..ec91c4a 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -45,3 +45,4 @@ obj-$(CONFIG_BACKLIGHT_PCF50633)	+= pcf50633-backlight.o
 obj-$(CONFIG_BACKLIGHT_AAT2870) += aat2870_bl.o
 obj-$(CONFIG_BACKLIGHT_OT200) += ot200_bl.o
 obj-$(CONFIG_BACKLIGHT_TPS65217) += tps65217_bl.o
+obj-$(CONFIG_BACKLIGHT_GPIO)	+= gpio_backlight.o
diff --git a/drivers/video/backlight/gpio_backlight.c b/drivers/video/backlight/gpio_backlight.c
new file mode 100644
index 0000000..5a8cd34
--- /dev/null
+++ b/drivers/video/backlight/gpio_backlight.c
@@ -0,0 +1,158 @@
+/*
+ * gpio_backlight.c - Simple GPIO-controlled backlight
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/backlight.h>
+#include <linux/err.h>
+#include <linux/fb.h>
+#include <linux/gpio.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <video/gpio_backlight.h>
+
+struct gpio_backlight {
+	struct device *dev;
+	struct device *fbdev;
+
+	int gpio;
+	int active;
+};
+
+static int gpio_backlight_update_status(struct backlight_device *bl)
+{
+	struct gpio_backlight *gbl = bl_get_data(bl);
+	int brightness = bl->props.brightness;
+
+	if (bl->props.power != FB_BLANK_UNBLANK ||
+	    bl->props.fb_blank != FB_BLANK_UNBLANK ||
+	    bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
+		brightness = 0;
+
+	gpio_set_value(gbl->gpio, brightness ? gbl->active : !gbl->active);
+
+	return 0;
+}
+
+static int gpio_backlight_get_brightness(struct backlight_device *bl)
+{
+	return bl->props.brightness;
+}
+
+static int gpio_backlight_check_fb(struct backlight_device *bl,
+				   struct fb_info *info)
+{
+	struct gpio_backlight *gbl = bl_get_data(bl);
+
+	return gbl->fbdev = info->dev;
+}
+
+static const struct backlight_ops gpio_backlight_ops = {
+	.update_status	= gpio_backlight_update_status,
+	.get_brightness	= gpio_backlight_get_brightness,
+	.check_fb	= gpio_backlight_check_fb,
+};
+
+#ifdef CONFIG_PM
+static int gpio_backlight_suspend(struct device *dev)
+{
+	struct backlight_device *bl = dev_get_drvdata(dev);
+	struct gpio_backlight *gbl = bl_get_data(bl);
+
+	gpio_set_value(gbl->gpio, !gbl->active);
+
+	return 0;
+}
+
+static int gpio_backlight_resume(struct device *dev)
+{
+	struct backlight_device *bl = dev_get_drvdata(dev);
+
+	backlight_update_status(bl);
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(gpio_backlight_pm_ops, gpio_backlight_suspend,
+			 gpio_backlight_resume);
+
+#endif
+
+static int __devinit gpio_backlight_probe(struct platform_device *pdev)
+{
+	struct gpio_backlight_platform_data *pdata = pdev->dev.platform_data;
+	struct backlight_properties props;
+	struct backlight_device *bl;
+	struct gpio_backlight *gbl;
+	int ret;
+
+	gbl = devm_kzalloc(&pdev->dev, sizeof(*gbl), GFP_KERNEL);
+	if (gbl = NULL)
+		return -ENOMEM;
+
+	gbl->dev = &pdev->dev;
+
+	if (!pdata) {
+		dev_err(&pdev->dev, "failed to find platform data\n");
+		return -ENODEV;
+	}
+
+	gbl->fbdev = pdata->fbdev;
+	gbl->gpio = pdata->gpio;
+	gbl->active = pdata->active_low ? 0 : 1;
+
+	ret = devm_gpio_request_one(gbl->dev, gbl->gpio, GPIOF_DIR_OUT,
+				    pdata->name);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "unable to request GPIO\n");
+		return ret;
+	}
+
+	memset(&props, 0, sizeof(props));
+	props.type = BACKLIGHT_RAW;
+	props.max_brightness = 1;
+	bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, gbl,
+				       &gpio_backlight_ops, &props);
+	if (IS_ERR(bl)) {
+		dev_err(&pdev->dev, "failed to register backlight\n");
+		return PTR_ERR(bl);
+	}
+
+	bl->props.brightness = pdata->def_value;
+	backlight_update_status(bl);
+
+	platform_set_drvdata(pdev, bl);
+	return 0;
+}
+
+static int __devexit gpio_backlight_remove(struct platform_device *pdev)
+{
+	struct backlight_device *bl = platform_get_drvdata(pdev);
+
+	backlight_device_unregister(bl);
+	return 0;
+}
+
+static struct platform_driver gpio_backlight_driver = {
+	.driver		= {
+		.name		= "gpio-backlight",
+		.owner		= THIS_MODULE,
+#ifdef CONFIG_PM
+		.pm		= &gpio_backlight_pm_ops,
+#endif
+	},
+	.probe		= gpio_backlight_probe,
+	.remove		= __devexit_p(gpio_backlight_remove),
+};
+
+module_platform_driver(gpio_backlight_driver);
+
+MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>");
+MODULE_DESCRIPTION("GPIO-based Backlight Driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:gpio-backlight");
diff --git a/include/video/gpio_backlight.h b/include/video/gpio_backlight.h
new file mode 100644
index 0000000..5ae0d9c
--- /dev/null
+++ b/include/video/gpio_backlight.h
@@ -0,0 +1,21 @@
+/*
+ * gpio_backlight.h - Simple GPIO-controlled backlight
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#ifndef __GPIO_BACKLIGHT_H__
+#define __GPIO_BACKLIGHT_H__
+
+struct device;
+
+struct gpio_backlight_platform_data {
+	struct device *fbdev;
+	int gpio;
+	int def_value;
+	bool active_low;
+	const char *name;
+};
+
+#endif
-- 
1.7.8.6

Re: [PATCH 1/5] backlight: Add GPIO-based backlight driver

[Jingoo Han]

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Re: [PATCH 1/5] backlight: Add GPIO-based backlight driver

[Laurent Pinchart]

Hi Jingoo,

On Monday 26 November 2012 09:49:36 Jingoo Han wrote:
> On Saturday, November 24, 2012 1:35 AM, Laurent Pinchart wrote
> > 
> > Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> 
> CC'ed Andrew Morton
> 
> It looks good. Also, I tested this patch with SMDK4210 board.
> Acked-by: Jingoo Han <jg1.han@samsung.com>

Thank you.

Unless Richard wants to take 1/5 and 2/5, I plan to push them through either 
the Renesas ARM or Renesas SH tree with the board code patches.

-- 
Regards,

Laurent Pinchart

Re: [PATCH 1/5] backlight: Add GPIO-based backlight driver

[Lars-Peter Clausen]

On 11/26/2012 10:49 AM, Jingoo Han wrote:
> On Saturday, November 24, 2012 1:35 AM, Laurent Pinchart wrote
[...]
>> +static int gpio_backlight_check_fb(struct backlight_device *bl,
>> +				   struct fb_info *info)
>> +{
>> +	struct gpio_backlight *gbl = bl_get_data(bl);
>> +
>> +	return gbl->fbdev = info->dev;

I think it makes sense to return true if fbdev is NULL, to provide a simple
fallback for systems with only one framebuffer device.

>> +}
>> +
[...]
>> +#ifdef CONFIG_PM
>> +static int gpio_backlight_suspend(struct device *dev)
>> +{
>> +	struct backlight_device *bl = dev_get_drvdata(dev);
>> +	struct gpio_backlight *gbl = bl_get_data(bl);
>> +
>> +	gpio_set_value(gbl->gpio, !gbl->active);
>> +
>> +	return 0;
>> +}
>> +
>> +static int gpio_backlight_resume(struct device *dev)
>> +{
>> +	struct backlight_device *bl = dev_get_drvdata(dev);
>> +
>> +	backlight_update_status(bl);
>> +	return 0;
>> +}

If you use BL_CORE_SUSPENDRESUME you can get rid of the custom
suspend/resume handlers.

>> +
>> +static SIMPLE_DEV_PM_OPS(gpio_backlight_pm_ops, gpio_backlight_suspend,
>> +			 gpio_backlight_resume);
>> +
>> +#endif
>> +
[...]

Re: [PATCH 1/5] backlight: Add GPIO-based backlight driver

[Laurent Pinchart]

Hi Lars-Peter,

On Monday 26 November 2012 11:44:04 Lars-Peter Clausen wrote:
> On 11/26/2012 10:49 AM, Jingoo Han wrote:
> > On Saturday, November 24, 2012 1:35 AM, Laurent Pinchart wrote
> 
> [...]
> 
> >> +static int gpio_backlight_check_fb(struct backlight_device *bl,
> >> +				   struct fb_info *info)
> >> +{
> >> +	struct gpio_backlight *gbl = bl_get_data(bl);
> >> +
> >> +	return gbl->fbdev = info->dev;
> 
> I think it makes sense to return true if fbdev is NULL, to provide a simple
> fallback for systems with only one framebuffer device.

Agreed, I'll change that.

> >> +}
> >> +
> 
> [...]
> 
> >> +#ifdef CONFIG_PM
> >> +static int gpio_backlight_suspend(struct device *dev)
> >> +{
> >> +	struct backlight_device *bl = dev_get_drvdata(dev);
> >> +	struct gpio_backlight *gbl = bl_get_data(bl);
> >> +
> >> +	gpio_set_value(gbl->gpio, !gbl->active);
> >> +
> >> +	return 0;
> >> +}
> >> +
> >> +static int gpio_backlight_resume(struct device *dev)
> >> +{
> >> +	struct backlight_device *bl = dev_get_drvdata(dev);
> >> +
> >> +	backlight_update_status(bl);
> >> +	return 0;
> >> +}
> 
> If you use BL_CORE_SUSPENDRESUME you can get rid of the custom
> suspend/resume handlers.

Good point, I'll do that.

> >> +
> >> +static SIMPLE_DEV_PM_OPS(gpio_backlight_pm_ops, gpio_backlight_suspend,
> >> +			 gpio_backlight_resume);
> >> +
> >> +#endif
> >> +

-- 
Regards,

Laurent Pinchart

Re: [PATCH 1/5] backlight: Add GPIO-based backlight driver

[Jingoo Han]

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Re: [PATCH 1/5] backlight: Add GPIO-based backlight driver

[Jingoo Han]

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cywNCkppbmdvbyBIYW4NCg0KDQo

Re: [PATCH 1/5] backlight: Add GPIO-based backlight driver

[Laurent Pinchart]

Hi Jingoo,

On Tuesday 27 November 2012 01:10:36 Jingoo Han wrote:
> On Saturday, November 24, 2012 1:35 AM, Laurent Pinchart wrote
> 
> > 
> > Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > ---
> > 
> >  drivers/video/backlight/Kconfig          |    7 ++
> >  drivers/video/backlight/Makefile         |    1 +
> >  drivers/video/backlight/gpio_backlight.c |  158 +++++++++++++++++++++++++
> >  include/video/gpio_backlight.h           |   21 ++++
> >  4 files changed, 187 insertions(+), 0 deletions(-)
> >  create mode 100644 drivers/video/backlight/gpio_backlight.c
> >  create mode 100644 include/video/gpio_backlight.h
> 
> 
> [...]
> 
> 
> > +static int __devinit gpio_backlight_probe(struct platform_device *pdev)
> > +{
> > +	struct gpio_backlight_platform_data *pdata = pdev->dev.platform_data;
> > +	struct backlight_properties props;
> > +	struct backlight_device *bl;
> > +	struct gpio_backlight *gbl;
> > +	int ret;
> > +
> > +	gbl = devm_kzalloc(&pdev->dev, sizeof(*gbl), GFP_KERNEL);
> > +	if (gbl = NULL)
> > +		return -ENOMEM;
> > +
> > +	gbl->dev = &pdev->dev;
> > +
> > +	if (!pdata) {
> > +		dev_err(&pdev->dev, "failed to find platform data\n");
> > +		return -ENODEV;
> > +	}
> > +
> > +	gbl->fbdev = pdata->fbdev;
> > +	gbl->gpio = pdata->gpio;
> > +	gbl->active = pdata->active_low ? 0 : 1;
> > +
> > +	ret = devm_gpio_request_one(gbl->dev, gbl->gpio, GPIOF_DIR_OUT,
> > +				    pdata->name);
> 
> 
> Please use GPIOF_INIT flags if you want to turn off GPIO backlight.
> If gbl->active is inverted, GPIOF_INIT_HIGH can be used as below:
> 
> 	ret = devm_gpio_request_one(gbl->dev, gbl->gpio,
> 				    GPIOF_DIR_OUT | (gbl->active ?
> 				    GPIOF_INIT_LOW : GPIOF_INIT_HIGH),
> 				    pdata->name);

Good point, thank you. I'll fix that.

> > +	if (ret < 0) {
> > +		dev_err(&pdev->dev, "unable to request GPIO\n");
> > +		return ret;
> > +	}
> > +
> > +	memset(&props, 0, sizeof(props));
> > +	props.type = BACKLIGHT_RAW;
> > +	props.max_brightness = 1;
> > +	bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, gbl,
> > +				       &gpio_backlight_ops, &props);
> > +	if (IS_ERR(bl)) {
> > +		dev_err(&pdev->dev, "failed to register backlight\n");
> > +		return PTR_ERR(bl);
> > +	}
> > +
> > +	bl->props.brightness = pdata->def_value;
> > +	backlight_update_status(bl);
> > +
> > +	platform_set_drvdata(pdev, bl);
> > +	return 0;
> > +}

-- 
Regards,

Laurent Pinchart