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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * gpio_backlight.c - Simple GPIO-controlled backlight4 */5 6#include <linux/backlight.h>7#include <linux/err.h>8#include <linux/gpio/consumer.h>9#include <linux/init.h>10#include <linux/kernel.h>11#include <linux/module.h>12#include <linux/of.h>13#include <linux/platform_data/gpio_backlight.h>14#include <linux/platform_device.h>15#include <linux/property.h>16#include <linux/slab.h>17 18struct gpio_backlight {19 struct device *dev;20 struct gpio_desc *gpiod;21};22 23static int gpio_backlight_update_status(struct backlight_device *bl)24{25 struct gpio_backlight *gbl = bl_get_data(bl);26 27 gpiod_set_value_cansleep(gbl->gpiod, backlight_get_brightness(bl));28 29 return 0;30}31 32static bool gpio_backlight_controls_device(struct backlight_device *bl,33 struct device *display_dev)34{35 struct gpio_backlight *gbl = bl_get_data(bl);36 37 return !gbl->dev || gbl->dev == display_dev;38}39 40static const struct backlight_ops gpio_backlight_ops = {41 .options = BL_CORE_SUSPENDRESUME,42 .update_status = gpio_backlight_update_status,43 .controls_device = gpio_backlight_controls_device,44};45 46static int gpio_backlight_probe(struct platform_device *pdev)47{48 struct device *dev = &pdev->dev;49 struct gpio_backlight_platform_data *pdata = dev_get_platdata(dev);50 struct device_node *of_node = dev->of_node;51 struct backlight_properties props;52 struct backlight_device *bl;53 struct gpio_backlight *gbl;54 int ret, init_brightness, def_value;55 56 gbl = devm_kzalloc(dev, sizeof(*gbl), GFP_KERNEL);57 if (gbl == NULL)58 return -ENOMEM;59 60 if (pdata)61 gbl->dev = pdata->dev;62 63 def_value = device_property_read_bool(dev, "default-on");64 65 gbl->gpiod = devm_gpiod_get(dev, NULL, GPIOD_ASIS);66 if (IS_ERR(gbl->gpiod))67 return dev_err_probe(dev, PTR_ERR(gbl->gpiod),68 "The gpios parameter is missing or invalid\n");69 70 memset(&props, 0, sizeof(props));71 props.type = BACKLIGHT_RAW;72 props.max_brightness = 1;73 bl = devm_backlight_device_register(dev, dev_name(dev), dev, gbl,74 &gpio_backlight_ops, &props);75 if (IS_ERR(bl)) {76 dev_err(dev, "failed to register backlight\n");77 return PTR_ERR(bl);78 }79 80 /* Set the initial power state */81 if (!of_node || !of_node->phandle)82 /* Not booted with device tree or no phandle link to the node */83 bl->props.power = def_value ? BACKLIGHT_POWER_ON84 : BACKLIGHT_POWER_OFF;85 else if (gpiod_get_value_cansleep(gbl->gpiod) == 0)86 bl->props.power = BACKLIGHT_POWER_OFF;87 else88 bl->props.power = BACKLIGHT_POWER_ON;89 90 bl->props.brightness = 1;91 92 init_brightness = backlight_get_brightness(bl);93 ret = gpiod_direction_output(gbl->gpiod, init_brightness);94 if (ret) {95 dev_err(dev, "failed to set initial brightness\n");96 return ret;97 }98 99 platform_set_drvdata(pdev, bl);100 return 0;101}102 103static struct of_device_id gpio_backlight_of_match[] = {104 { .compatible = "gpio-backlight" },105 { /* sentinel */ }106};107 108MODULE_DEVICE_TABLE(of, gpio_backlight_of_match);109 110static struct platform_driver gpio_backlight_driver = {111 .driver = {112 .name = "gpio-backlight",113 .of_match_table = gpio_backlight_of_match,114 },115 .probe = gpio_backlight_probe,116};117 118module_platform_driver(gpio_backlight_driver);119 120MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>");121MODULE_DESCRIPTION("GPIO-based Backlight Driver");122MODULE_LICENSE("GPL");123MODULE_ALIAS("platform:gpio-backlight");124