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Commit 8b770e3c authored by Laurent Pinchart's avatar Laurent Pinchart Committed by Simon Horman
Browse files

backlight: Add GPIO-based backlight driver 



The GPIO backlight driver controls the backlight in on/off mode through
a single GPIO.

Signed-off-by: default avatarLaurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: default avatarJingoo Han <jg1.han@samsung.com>
Signed-off-by: default avatarSimon Horman <horms+renesas@verge.net.au>
parent ad81f054

drivers/video/backlight/Kconfig

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Original line number Diff line number Diff line
@@ -425,6 +425,13 @@ config BACKLIGHT_AS3711 
	  If you have an Austrian Microsystems AS3711 say Y to enable the

	  backlight driver.



config BACKLIGHT_GPIO

	tristate "Generic GPIO based Backlight Driver"

	depends on GPIOLIB

	help

	  If you have a LCD backlight adjustable by GPIO, say Y to enable

	  this driver.



endif # BACKLIGHT_CLASS_DEVICE



endif # BACKLIGHT_LCD_SUPPORT

drivers/video/backlight/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -32,6 +32,7 @@ obj-$(CONFIG_BACKLIGHT_DA903X) += da903x_bl.o 
obj-$(CONFIG_BACKLIGHT_DA9052)		+= da9052_bl.o

obj-$(CONFIG_BACKLIGHT_EP93XX)		+= ep93xx_bl.o

obj-$(CONFIG_BACKLIGHT_GENERIC)		+= generic_bl.o

obj-$(CONFIG_BACKLIGHT_GPIO)		+= gpio_backlight.o

obj-$(CONFIG_BACKLIGHT_HP680)		+= hp680_bl.o

obj-$(CONFIG_BACKLIGHT_HP700)		+= jornada720_bl.o

obj-$(CONFIG_BACKLIGHT_LM3533)		+= lm3533_bl.o

drivers/video/backlight/gpio_backlight.c

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/*

 * 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_data/gpio_backlight.h>

#include <linux/platform_device.h>

#include <linux/slab.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 == NULL || gbl->fbdev == info->dev;

}



static const struct backlight_ops gpio_backlight_ops = {

	.options	= BL_CORE_SUSPENDRESUME,

	.update_status	= gpio_backlight_update_status,

	.get_brightness	= gpio_backlight_get_brightness,

	.check_fb	= gpio_backlight_check_fb,

};



static int 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;



	if (!pdata) {

		dev_err(&pdev->dev, "failed to find platform data\n");

		return -ENODEV;

	}



	gbl = devm_kzalloc(&pdev->dev, sizeof(*gbl), GFP_KERNEL);

	if (gbl == NULL)

		return -ENOMEM;



	gbl->dev = &pdev->dev;

	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 |

				    (gbl->active ? GPIOF_INIT_LOW

						 : GPIOF_INIT_HIGH),

				    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 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,

	},

	.probe		= gpio_backlight_probe,

	.remove		= 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");

include/linux/platform_data/gpio_backlight.h

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/*

 * 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