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Laurent Pincharthorms
Laurent Pinchart
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horms
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backlight: Add GPIO-based backlight driver
The GPIO backlight driver controls the backlight in on/off mode through a single GPIO. Signed-off-by: Laurent Pinchart <[email protected]> Acked-by: Jingoo Han <[email protected]> Signed-off-by: Simon Horman <[email protected]>
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‎drivers/video/backlight/Kconfig

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@@ -425,6 +425,13 @@ config BACKLIGHT_AS3711
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If you have an Austrian Microsystems AS3711 say Y to enable the
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backlight driver.
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config BACKLIGHT_GPIO
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tristate "Generic GPIO based Backlight Driver"
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depends on GPIOLIB
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help
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If you have a LCD backlight adjustable by GPIO, say Y to enable
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this driver.
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endif # BACKLIGHT_CLASS_DEVICE
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endif # BACKLIGHT_LCD_SUPPORT

‎drivers/video/backlight/Makefile

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@@ -32,6 +32,7 @@ obj-$(CONFIG_BACKLIGHT_DA903X) += da903x_bl.o
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obj-$(CONFIG_BACKLIGHT_DA9052) += da9052_bl.o
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obj-$(CONFIG_BACKLIGHT_EP93XX) += ep93xx_bl.o
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obj-$(CONFIG_BACKLIGHT_GENERIC) += generic_bl.o
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obj-$(CONFIG_BACKLIGHT_GPIO) += gpio_backlight.o
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obj-$(CONFIG_BACKLIGHT_HP680) += hp680_bl.o
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obj-$(CONFIG_BACKLIGHT_HP700) += jornada720_bl.o
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obj-$(CONFIG_BACKLIGHT_LM3533) += lm3533_bl.o

‎drivers/video/backlight/gpio_backlight.c

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/*
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* gpio_backlight.c - Simple GPIO-controlled backlight
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/backlight.h>
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#include <linux/err.h>
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#include <linux/fb.h>
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#include <linux/gpio.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/platform_data/gpio_backlight.h>
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#include <linux/platform_device.h>
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#include <linux/slab.h>
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struct gpio_backlight {
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struct device *dev;
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struct device *fbdev;
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int gpio;
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int active;
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};
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static int gpio_backlight_update_status(struct backlight_device *bl)
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{
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struct gpio_backlight *gbl = bl_get_data(bl);
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int brightness = bl->props.brightness;
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if (bl->props.power != FB_BLANK_UNBLANK ||
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bl->props.fb_blank != FB_BLANK_UNBLANK ||
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bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
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brightness = 0;
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gpio_set_value(gbl->gpio, brightness ? gbl->active : !gbl->active);
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return 0;
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}
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static int gpio_backlight_get_brightness(struct backlight_device *bl)
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{
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return bl->props.brightness;
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}
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static int gpio_backlight_check_fb(struct backlight_device *bl,
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struct fb_info *info)
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{
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struct gpio_backlight *gbl = bl_get_data(bl);
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return gbl->fbdev == NULL || gbl->fbdev == info->dev;
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}
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static const struct backlight_ops gpio_backlight_ops = {
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.options = BL_CORE_SUSPENDRESUME,
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.update_status = gpio_backlight_update_status,
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.get_brightness = gpio_backlight_get_brightness,
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.check_fb = gpio_backlight_check_fb,
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};
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static int gpio_backlight_probe(struct platform_device *pdev)
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{
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struct gpio_backlight_platform_data *pdata = pdev->dev.platform_data;
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struct backlight_properties props;
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struct backlight_device *bl;
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struct gpio_backlight *gbl;
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int ret;
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if (!pdata) {
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dev_err(&pdev->dev, "failed to find platform data\n");
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return -ENODEV;
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}
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gbl = devm_kzalloc(&pdev->dev, sizeof(*gbl), GFP_KERNEL);
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if (gbl == NULL)
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return -ENOMEM;
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gbl->dev = &pdev->dev;
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gbl->fbdev = pdata->fbdev;
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gbl->gpio = pdata->gpio;
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gbl->active = pdata->active_low ? 0 : 1;
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ret = devm_gpio_request_one(gbl->dev, gbl->gpio, GPIOF_DIR_OUT |
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(gbl->active ? GPIOF_INIT_LOW
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: GPIOF_INIT_HIGH),
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pdata->name);
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if (ret < 0) {
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dev_err(&pdev->dev, "unable to request GPIO\n");
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return ret;
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}
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memset(&props, 0, sizeof(props));
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props.type = BACKLIGHT_RAW;
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props.max_brightness = 1;
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bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, gbl,
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&gpio_backlight_ops, &props);
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if (IS_ERR(bl)) {
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dev_err(&pdev->dev, "failed to register backlight\n");
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return PTR_ERR(bl);
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}
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bl->props.brightness = pdata->def_value;
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backlight_update_status(bl);
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platform_set_drvdata(pdev, bl);
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return 0;
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}
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static int gpio_backlight_remove(struct platform_device *pdev)
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{
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struct backlight_device *bl = platform_get_drvdata(pdev);
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backlight_device_unregister(bl);
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return 0;
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}
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static struct platform_driver gpio_backlight_driver = {
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.driver = {
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.name = "gpio-backlight",
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.owner = THIS_MODULE,
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},
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.probe = gpio_backlight_probe,
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.remove = gpio_backlight_remove,
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};
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module_platform_driver(gpio_backlight_driver);
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MODULE_AUTHOR("Laurent Pinchart <[email protected]>");
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MODULE_DESCRIPTION("GPIO-based Backlight Driver");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("platform:gpio-backlight");

‎include/linux/platform_data/gpio_backlight.h

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/*
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* gpio_backlight.h - Simple GPIO-controlled backlight
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#ifndef __GPIO_BACKLIGHT_H__
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#define __GPIO_BACKLIGHT_H__
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struct device;
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struct gpio_backlight_platform_data {
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struct device *fbdev;
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int gpio;
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int def_value;
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bool active_low;
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const char *name;
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};
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#endif

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