LXR linux/drivers/video/backlight/gpio

   1/*
   2 * gpio_backlight.c - Simple GPIO-controlled backlight
   3 *
   4 * This program is free software; you can redistribute it and/or modify
   5 * it under the terms of the GNU General Public License version 2 as
   6 * published by the Free Software Foundation.
   7 */
   8
   9#include <linux/backlight.h>
  10#include <linux/err.h>
  11#include <linux/fb.h>
  12#include <linux/gpio.h>
  13#include <linux/init.h>
  14#include <linux/kernel.h>
  15#include <linux/module.h>
  16#include <linux/platform_data/gpio_backlight.h>
  17#include <linux/platform_device.h>
  18#include <linux/slab.h>
  19
  20struct gpio_backlight {
  21        struct device *dev;
  22        struct device *fbdev;
  23
  24        int gpio;
  25        int active;
  26};
  27
  28static int gpio_backlight_update_status(struct backlight_device *bl)
  29{
  30        struct gpio_backlight *gbl = bl_get_data(bl);
  31        int brightness = bl->props.brightness;
  32
  33        if (bl->props.power != FB_BLANK_UNBLANK ||
  34            bl->props.fb_blank != FB_BLANK_UNBLANK ||
  35            bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
  36                brightness = 0;
  37
  38        gpio_set_value(gbl->gpio, brightness ? gbl->active : !gbl->active);
  39
  40        return 0;
  41}
  42
  43static int gpio_backlight_get_brightness(struct backlight_device *bl)
  44{
  45        return bl->props.brightness;
  46}
  47
  48static int gpio_backlight_check_fb(struct backlight_device *bl,
  49                                   struct fb_info *info)
  50{
  51        struct gpio_backlight *gbl = bl_get_data(bl);
  52
  53        return gbl->fbdev == NULL || gbl->fbdev == info->dev;
  54}
  55
  56static const struct backlight_ops gpio_backlight_ops = {
  57        .options        = BL_CORE_SUSPENDRESUME,
  58        .update_status  = gpio_backlight_update_status,
  59        .get_brightness = gpio_backlight_get_brightness,
  60        .check_fb       = gpio_backlight_check_fb,
  61};
  62
  63static int gpio_backlight_probe(struct platform_device *pdev)
  64{
  65        struct gpio_backlight_platform_data *pdata = pdev->dev.platform_data;
  66        struct backlight_properties props;
  67        struct backlight_device *bl;
  68        struct gpio_backlight *gbl;
  69        int ret;
  70
  71        if (!pdata) {
  72                dev_err(&pdev->dev, "failed to find platform data\n");
  73                return -ENODEV;
  74        }
  75
  76        gbl = devm_kzalloc(&pdev->dev, sizeof(*gbl), GFP_KERNEL);
  77        if (gbl == NULL)
  78                return -ENOMEM;
  79
  80        gbl->dev = &pdev->dev;
  81        gbl->fbdev = pdata->fbdev;
  82        gbl->gpio = pdata->gpio;
  83        gbl->active = pdata->active_low ? 0 : 1;
  84
  85        ret = devm_gpio_request_one(gbl->dev, gbl->gpio, GPIOF_DIR_OUT |
  86                                    (gbl->active ? GPIOF_INIT_LOW
  87                                                 : GPIOF_INIT_HIGH),
  88                                    pdata->name);
  89        if (ret < 0) {
  90                dev_err(&pdev->dev, "unable to request GPIO\n");
  91                return ret;
  92        }
  93
  94        memset(&props, 0, sizeof(props));
  95        props.type = BACKLIGHT_RAW;
  96        props.max_brightness = 1;
  97        bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, gbl,
  98                                       &gpio_backlight_ops, &props);
  99        if (IS_ERR(bl)) {
 100                dev_err(&pdev->dev, "failed to register backlight\n");
 101                return PTR_ERR(bl);
 102        }
 103
 104        bl->props.brightness = pdata->def_value;
 105        backlight_update_status(bl);
 106
 107        platform_set_drvdata(pdev, bl);
 108        return 0;
 109}
 110
 111static int gpio_backlight_remove(struct platform_device *pdev)
 112{
 113        struct backlight_device *bl = platform_get_drvdata(pdev);
 114
 115        backlight_device_unregister(bl);
 116        return 0;
 117}
 118
 119static struct platform_driver gpio_backlight_driver = {
 120        .driver         = {
 121                .name           = "gpio-backlight",
 122                .owner          = THIS_MODULE,
 123        },
 124        .probe          = gpio_backlight_probe,
 125        .remove         = gpio_backlight_remove,
 126};
 127
 128module_platform_driver(gpio_backlight_driver);
 129
 130MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>");
 131MODULE_DESCRIPTION("GPIO-based Backlight Driver");
 132MODULE_LICENSE("GPL");
 133MODULE_ALIAS("platform:gpio-backlight");
 134