LXR linux/drivers/video/backlight/gpio

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * gpio_backlight.c - Simple GPIO-controlled backlight
   4 */
   5
   6#include <linux/backlight.h>
   7#include <linux/err.h>
   8#include <linux/fb.h>
   9#include <linux/gpio/consumer.h>
  10#include <linux/init.h>
  11#include <linux/kernel.h>
  12#include <linux/module.h>
  13#include <linux/of.h>
  14#include <linux/platform_data/gpio_backlight.h>
  15#include <linux/platform_device.h>
  16#include <linux/property.h>
  17#include <linux/slab.h>
  18
  19struct gpio_backlight {
  20        struct device *fbdev;
  21        struct gpio_desc *gpiod;
  22};
  23
  24static int gpio_backlight_get_next_brightness(struct backlight_device *bl)
  25{
  26        int brightness = bl->props.brightness;
  27
  28        if (bl->props.power != FB_BLANK_UNBLANK ||
  29            bl->props.fb_blank != FB_BLANK_UNBLANK ||
  30            bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
  31                brightness = 0;
  32
  33        return brightness;
  34}
  35
  36static int gpio_backlight_update_status(struct backlight_device *bl)
  37{
  38        struct gpio_backlight *gbl = bl_get_data(bl);
  39        int brightness = gpio_backlight_get_next_brightness(bl);
  40
  41        gpiod_set_value_cansleep(gbl->gpiod, brightness);
  42
  43        return 0;
  44}
  45
  46static int gpio_backlight_check_fb(struct backlight_device *bl,
  47                                   struct fb_info *info)
  48{
  49        struct gpio_backlight *gbl = bl_get_data(bl);
  50
  51        return gbl->fbdev == NULL || gbl->fbdev == info->dev;
  52}
  53
  54static const struct backlight_ops gpio_backlight_ops = {
  55        .options        = BL_CORE_SUSPENDRESUME,
  56        .update_status  = gpio_backlight_update_status,
  57        .check_fb       = gpio_backlight_check_fb,
  58};
  59
  60static int gpio_backlight_probe(struct platform_device *pdev)
  61{
  62        struct device *dev = &pdev->dev;
  63        struct gpio_backlight_platform_data *pdata = dev_get_platdata(dev);
  64        struct device_node *of_node = dev->of_node;
  65        struct backlight_properties props;
  66        struct backlight_device *bl;
  67        struct gpio_backlight *gbl;
  68        int ret, init_brightness, def_value;
  69
  70        gbl = devm_kzalloc(dev, sizeof(*gbl), GFP_KERNEL);
  71        if (gbl == NULL)
  72                return -ENOMEM;
  73
  74        if (pdata)
  75                gbl->fbdev = pdata->fbdev;
  76
  77        def_value = device_property_read_bool(dev, "default-on");
  78
  79        gbl->gpiod = devm_gpiod_get(dev, NULL, GPIOD_ASIS);
  80        if (IS_ERR(gbl->gpiod)) {
  81                ret = PTR_ERR(gbl->gpiod);
  82                if (ret != -EPROBE_DEFER)
  83                        dev_err(dev,
  84                                "Error: The gpios parameter is missing or invalid.\n");
  85                return ret;
  86        }
  87
  88        memset(&props, 0, sizeof(props));
  89        props.type = BACKLIGHT_RAW;
  90        props.max_brightness = 1;
  91        bl = devm_backlight_device_register(dev, dev_name(dev), dev, gbl,
  92                                            &gpio_backlight_ops, &props);
  93        if (IS_ERR(bl)) {
  94                dev_err(dev, "failed to register backlight\n");
  95                return PTR_ERR(bl);
  96        }
  97
  98        /* Set the initial power state */
  99        if (!of_node || !of_node->phandle)
 100                /* Not booted with device tree or no phandle link to the node */
 101                bl->props.power = def_value ? FB_BLANK_UNBLANK
 102                                            : FB_BLANK_POWERDOWN;
 103        else if (gpiod_get_direction(gbl->gpiod) == 0 &&
 104                 gpiod_get_value_cansleep(gbl->gpiod) == 0)
 105                bl->props.power = FB_BLANK_POWERDOWN;
 106        else
 107                bl->props.power = FB_BLANK_UNBLANK;
 108
 109        bl->props.brightness = 1;
 110
 111        init_brightness = gpio_backlight_get_next_brightness(bl);
 112        ret = gpiod_direction_output(gbl->gpiod, init_brightness);
 113        if (ret) {
 114                dev_err(dev, "failed to set initial brightness\n");
 115                return ret;
 116        }
 117
 118        platform_set_drvdata(pdev, bl);
 119        return 0;
 120}
 121
 122static struct of_device_id gpio_backlight_of_match[] = {
 123        { .compatible = "gpio-backlight" },
 124        { /* sentinel */ }
 125};
 126
 127MODULE_DEVICE_TABLE(of, gpio_backlight_of_match);
 128
 129static struct platform_driver gpio_backlight_driver = {
 130        .driver         = {
 131                .name           = "gpio-backlight",
 132                .of_match_table = gpio_backlight_of_match,
 133        },
 134        .probe          = gpio_backlight_probe,
 135};
 136
 137module_platform_driver(gpio_backlight_driver);
 138
 139MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>");
 140MODULE_DESCRIPTION("GPIO-based Backlight Driver");
 141MODULE_LICENSE("GPL");
 142MODULE_ALIAS("platform:gpio-backlight");
 143