From 8b770e3c9824c98eafe67950ad6e41e09ec9c98a Mon Sep 17 00:00:00 2001 From: Laurent Pinchart Date: Thu, 4 Jul 2013 21:13:24 +0200 Subject: 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 Acked-by: Jingoo Han Signed-off-by: Simon Horman --- drivers/video/backlight/gpio_backlight.c | 133 +++++++++++++++++++++++++++++++ 1 file changed, 133 insertions(+) create mode 100644 drivers/video/backlight/gpio_backlight.c (limited to 'drivers/video/backlight/gpio_backlight.c') diff --git a/drivers/video/backlight/gpio_backlight.c b/drivers/video/backlight/gpio_backlight.c new file mode 100644 index 000000000000..5fa217f9f445 --- /dev/null +++ b/drivers/video/backlight/gpio_backlight.c @@ -0,0 +1,133 @@ +/* + * 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 +#include +#include +#include +#include +#include +#include +#include +#include +#include + +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 "); +MODULE_DESCRIPTION("GPIO-based Backlight Driver"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("platform:gpio-backlight"); -- cgit v1.2.1