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.h> /* Only for legacy support */
  10#include <linux/gpio/consumer.h>
  11#include <linux/init.h>
  12#include <linux/kernel.h>
  13#include <linux/module.h>
  14#include <linux/of.h>
  15#include <linux/of_gpio.h>
  16#include <linux/platform_data/gpio_backlight.h>
  17#include <linux/platform_device.h>
  18#include <linux/property.h>
  19#include <linux/slab.h>
  20
  21struct gpio_backlight {
  22        struct device *dev;
  23        struct device *fbdev;
  24
  25        struct gpio_desc *gpiod;
  26        int def_value;
  27};
  28
  29static int gpio_backlight_update_status(struct backlight_device *bl)
  30{
  31        struct gpio_backlight *gbl = bl_get_data(bl);
  32        int brightness = bl->props.brightness;
  33
  34        if (bl->props.power != FB_BLANK_UNBLANK ||
  35            bl->props.fb_blank != FB_BLANK_UNBLANK ||
  36            bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
  37                brightness = 0;
  38
  39        gpiod_set_value_cansleep(gbl->gpiod, brightness);
  40
  41        return 0;
  42}
  43
  44static int gpio_backlight_check_fb(struct backlight_device *bl,
  45                                   struct fb_info *info)
  46{
  47        struct gpio_backlight *gbl = bl_get_data(bl);
  48
  49        return gbl->fbdev == NULL || gbl->fbdev == info->dev;
  50}
  51
  52static const struct backlight_ops gpio_backlight_ops = {
  53        .options        = BL_CORE_SUSPENDRESUME,
  54        .update_status  = gpio_backlight_update_status,
  55        .check_fb       = gpio_backlight_check_fb,
  56};
  57
  58static int gpio_backlight_probe_dt(struct platform_device *pdev,
  59                                   struct gpio_backlight *gbl)
  60{
  61        struct device *dev = &pdev->dev;
  62        enum gpiod_flags flags;
  63        int ret;
  64
  65        gbl->def_value = device_property_read_bool(dev, "default-on");
  66        flags = gbl->def_value ? GPIOD_OUT_HIGH : GPIOD_OUT_LOW;
  67
  68        gbl->gpiod = devm_gpiod_get(dev, NULL, flags);
  69        if (IS_ERR(gbl->gpiod)) {
  70                ret = PTR_ERR(gbl->gpiod);
  71
  72                if (ret != -EPROBE_DEFER) {
  73                        dev_err(dev,
  74                                "Error: The gpios parameter is missing or invalid.\n");
  75                }
  76                return ret;
  77        }
  78
  79        return 0;
  80}
  81
  82static int gpio_backlight_probe(struct platform_device *pdev)
  83{
  84        struct gpio_backlight_platform_data *pdata =
  85                dev_get_platdata(&pdev->dev);
  86        struct backlight_properties props;
  87        struct backlight_device *bl;
  88        struct gpio_backlight *gbl;
  89        int ret;
  90
  91        gbl = devm_kzalloc(&pdev->dev, sizeof(*gbl), GFP_KERNEL);
  92        if (gbl == NULL)
  93                return -ENOMEM;
  94
  95        gbl->dev = &pdev->dev;
  96
  97        if (pdev->dev.fwnode) {
  98                ret = gpio_backlight_probe_dt(pdev, gbl);
  99                if (ret)
 100                        return ret;
 101        } else if (pdata) {
 102                /*
 103                 * Legacy platform data GPIO retrieveal. Do not expand
 104                 * the use of this code path, currently only used by one
 105                 * SH board.
 106                 */
 107                unsigned long flags = GPIOF_DIR_OUT;
 108
 109                gbl->fbdev = pdata->fbdev;
 110                gbl->def_value = pdata->def_value;
 111                flags |= gbl->def_value ? GPIOF_INIT_HIGH : GPIOF_INIT_LOW;
 112
 113                ret = devm_gpio_request_one(gbl->dev, pdata->gpio, flags,
 114                                            pdata ? pdata->name : "backlight");
 115                if (ret < 0) {
 116                        dev_err(&pdev->dev, "unable to request GPIO\n");
 117                        return ret;
 118                }
 119                gbl->gpiod = gpio_to_desc(pdata->gpio);
 120                if (!gbl->gpiod)
 121                        return -EINVAL;
 122        } else {
 123                dev_err(&pdev->dev,
 124                        "failed to find platform data or device tree node.\n");
 125                return -ENODEV;
 126        }
 127
 128        memset(&props, 0, sizeof(props));
 129        props.type = BACKLIGHT_RAW;
 130        props.max_brightness = 1;
 131        bl = devm_backlight_device_register(&pdev->dev, dev_name(&pdev->dev),
 132                                        &pdev->dev, gbl, &gpio_backlight_ops,
 133                                        &props);
 134        if (IS_ERR(bl)) {
 135                dev_err(&pdev->dev, "failed to register backlight\n");
 136                return PTR_ERR(bl);
 137        }
 138
 139        bl->props.brightness = gbl->def_value;
 140        backlight_update_status(bl);
 141
 142        platform_set_drvdata(pdev, bl);
 143        return 0;
 144}
 145
 146static struct of_device_id gpio_backlight_of_match[] = {
 147        { .compatible = "gpio-backlight" },
 148        { /* sentinel */ }
 149};
 150
 151MODULE_DEVICE_TABLE(of, gpio_backlight_of_match);
 152
 153static struct platform_driver gpio_backlight_driver = {
 154        .driver         = {
 155                .name           = "gpio-backlight",
 156                .of_match_table = gpio_backlight_of_match,
 157        },
 158        .probe          = gpio_backlight_probe,
 159};
 160
 161module_platform_driver(gpio_backlight_driver);
 162
 163MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>");
 164MODULE_DESCRIPTION("GPIO-based Backlight Driver");
 165MODULE_LICENSE("GPL");
 166MODULE_ALIAS("platform:gpio-backlight");
 167