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_update_status(struct backlight_device *bl)
  25{
  26        struct gpio_backlight *gbl = bl_get_data(bl);
  27
  28        gpiod_set_value_cansleep(gbl->gpiod, backlight_get_brightness(bl));
  29
  30        return 0;
  31}
  32
  33static int gpio_backlight_check_fb(struct backlight_device *bl,
  34                                   struct fb_info *info)
  35{
  36        struct gpio_backlight *gbl = bl_get_data(bl);
  37
  38        return gbl->fbdev == NULL || gbl->fbdev == info->dev;
  39}
  40
  41static const struct backlight_ops gpio_backlight_ops = {
  42        .options        = BL_CORE_SUSPENDRESUME,
  43        .update_status  = gpio_backlight_update_status,
  44        .check_fb       = gpio_backlight_check_fb,
  45};
  46
  47static int gpio_backlight_probe(struct platform_device *pdev)
  48{
  49        struct device *dev = &pdev->dev;
  50        struct gpio_backlight_platform_data *pdata = dev_get_platdata(dev);
  51        struct device_node *of_node = dev->of_node;
  52        struct backlight_properties props;
  53        struct backlight_device *bl;
  54        struct gpio_backlight *gbl;
  55        int ret, init_brightness, def_value;
  56
  57        gbl = devm_kzalloc(dev, sizeof(*gbl), GFP_KERNEL);
  58        if (gbl == NULL)
  59                return -ENOMEM;
  60
  61        if (pdata)
  62                gbl->fbdev = pdata->fbdev;
  63
  64        def_value = device_property_read_bool(dev, "default-on");
  65
  66        gbl->gpiod = devm_gpiod_get(dev, NULL, GPIOD_ASIS);
  67        if (IS_ERR(gbl->gpiod)) {
  68                ret = PTR_ERR(gbl->gpiod);
  69                if (ret != -EPROBE_DEFER)
  70                        dev_err(dev,
  71                                "Error: The gpios parameter is missing or invalid.\n");
  72                return ret;
  73        }
  74
  75        memset(&props, 0, sizeof(props));
  76        props.type = BACKLIGHT_RAW;
  77        props.max_brightness = 1;
  78        bl = devm_backlight_device_register(dev, dev_name(dev), dev, gbl,
  79                                            &gpio_backlight_ops, &props);
  80        if (IS_ERR(bl)) {
  81                dev_err(dev, "failed to register backlight\n");
  82                return PTR_ERR(bl);
  83        }
  84
  85        /* Set the initial power state */
  86        if (!of_node || !of_node->phandle)
  87                /* Not booted with device tree or no phandle link to the node */
  88                bl->props.power = def_value ? FB_BLANK_UNBLANK
  89                                            : FB_BLANK_POWERDOWN;
  90        else if (gpiod_get_direction(gbl->gpiod) == 0 &&
  91                 gpiod_get_value_cansleep(gbl->gpiod) == 0)
  92                bl->props.power = FB_BLANK_POWERDOWN;
  93        else
  94                bl->props.power = FB_BLANK_UNBLANK;
  95
  96        bl->props.brightness = 1;
  97
  98        init_brightness = backlight_get_brightness(bl);
  99        ret = gpiod_direction_output(gbl->gpiod, init_brightness);
 100        if (ret) {
 101                dev_err(dev, "failed to set initial brightness\n");
 102                return ret;
 103        }
 104
 105        platform_set_drvdata(pdev, bl);
 106        return 0;
 107}
 108
 109static struct of_device_id gpio_backlight_of_match[] = {
 110        { .compatible = "gpio-backlight" },
 111        { /* sentinel */ }
 112};
 113
 114MODULE_DEVICE_TABLE(of, gpio_backlight_of_match);
 115
 116static struct platform_driver gpio_backlight_driver = {
 117        .driver         = {
 118                .name           = "gpio-backlight",
 119                .of_match_table = gpio_backlight_of_match,
 120        },
 121        .probe          = gpio_backlight_probe,
 122};
 123
 124module_platform_driver(gpio_backlight_driver);
 125
 126MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>");
 127MODULE_DESCRIPTION("GPIO-based Backlight Driver");
 128MODULE_LICENSE("GPL");
 129MODULE_ALIAS("platform:gpio-backlight");
 130