// SPDX-License-Identifier: GPL-2.0-only
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/*
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* gpio_backlight.c - Simple GPIO-controlled backlight
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*/
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#include <linux/backlight.h>
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#include <linux/err.h>
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#include <linux/fb.h>
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#include <linux/gpio/consumer.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/of.h>
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#include <linux/platform_data/gpio_backlight.h>
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#include <linux/platform_device.h>
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#include <linux/property.h>
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#include <linux/slab.h>
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struct gpio_backlight {
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struct device *fbdev;
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struct gpio_desc *gpiod;
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};
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static int gpio_backlight_update_status(struct backlight_device *bl)
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{
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struct gpio_backlight *gbl = bl_get_data(bl);
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gpiod_set_value_cansleep(gbl->gpiod, backlight_get_brightness(bl));
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return 0;
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}
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static int gpio_backlight_check_fb(struct backlight_device *bl,
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struct fb_info *info)
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{
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struct gpio_backlight *gbl = bl_get_data(bl);
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return gbl->fbdev == NULL || gbl->fbdev == info->dev;
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}
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static const struct backlight_ops gpio_backlight_ops = {
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.options = BL_CORE_SUSPENDRESUME,
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.update_status = gpio_backlight_update_status,
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.check_fb = gpio_backlight_check_fb,
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};
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static int gpio_backlight_probe(struct platform_device *pdev)
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{
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struct device *dev = &pdev->dev;
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struct gpio_backlight_platform_data *pdata = dev_get_platdata(dev);
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struct device_node *of_node = dev->of_node;
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struct backlight_properties props;
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struct backlight_device *bl;
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struct gpio_backlight *gbl;
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int ret, init_brightness, def_value;
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gbl = devm_kzalloc(dev, sizeof(*gbl), GFP_KERNEL);
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if (gbl == NULL)
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return -ENOMEM;
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if (pdata)
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gbl->fbdev = pdata->fbdev;
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def_value = device_property_read_bool(dev, "default-on");
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gbl->gpiod = devm_gpiod_get(dev, NULL, GPIOD_ASIS);
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if (IS_ERR(gbl->gpiod)) {
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ret = PTR_ERR(gbl->gpiod);
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if (ret != -EPROBE_DEFER)
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dev_err(dev,
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"Error: The gpios parameter is missing or invalid.\n");
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return ret;
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}
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memset(&props, 0, sizeof(props));
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props.type = BACKLIGHT_RAW;
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props.max_brightness = 1;
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bl = devm_backlight_device_register(dev, dev_name(dev), dev, gbl,
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&gpio_backlight_ops, &props);
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if (IS_ERR(bl)) {
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dev_err(dev, "failed to register backlight\n");
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return PTR_ERR(bl);
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}
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/* Set the initial power state */
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if (!of_node || !of_node->phandle)
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/* Not booted with device tree or no phandle link to the node */
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bl->props.power = def_value ? FB_BLANK_UNBLANK
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: FB_BLANK_POWERDOWN;
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else if (gpiod_get_direction(gbl->gpiod) == 0 &&
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gpiod_get_value_cansleep(gbl->gpiod) == 0)
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bl->props.power = FB_BLANK_POWERDOWN;
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else
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bl->props.power = FB_BLANK_UNBLANK;
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bl->props.brightness = 1;
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init_brightness = backlight_get_brightness(bl);
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ret = gpiod_direction_output(gbl->gpiod, init_brightness);
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if (ret) {
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dev_err(dev, "failed to set initial brightness\n");
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return ret;
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}
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platform_set_drvdata(pdev, bl);
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return 0;
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}
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static struct of_device_id gpio_backlight_of_match[] = {
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{ .compatible = "gpio-backlight" },
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{ /* sentinel */ }
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};
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MODULE_DEVICE_TABLE(of, gpio_backlight_of_match);
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static struct platform_driver gpio_backlight_driver = {
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.driver = {
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.name = "gpio-backlight",
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.of_match_table = gpio_backlight_of_match,
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},
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.probe = gpio_backlight_probe,
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};
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module_platform_driver(gpio_backlight_driver);
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MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>");
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MODULE_DESCRIPTION("GPIO-based Backlight Driver");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("platform:gpio-backlight");
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