v4.19.13 snapshot.
diff --git a/drivers/video/backlight/gpio_backlight.c b/drivers/video/backlight/gpio_backlight.c
new file mode 100644
index 0000000..e470da9
--- /dev/null
+++ b/drivers/video/backlight/gpio_backlight.c
@@ -0,0 +1,174 @@
+/*
+ * gpio_backlight.c - Simple GPIO-controlled backlight
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/backlight.h>
+#include <linux/err.h>
+#include <linux/fb.h>
+#include <linux/gpio.h> /* Only for legacy support */
+#include <linux/gpio/consumer.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_gpio.h>
+#include <linux/platform_data/gpio_backlight.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+struct gpio_backlight {
+ struct device *dev;
+ struct device *fbdev;
+
+ struct gpio_desc *gpiod;
+ int def_value;
+};
+
+static int gpio_backlight_update_status(struct backlight_device *bl)
+{
+ struct gpio_backlight *gbl = bl_get_data(bl);
+ int brightness = bl->props.brightness;
+
+ if (bl->props.power != FB_BLANK_UNBLANK ||
+ bl->props.fb_blank != FB_BLANK_UNBLANK ||
+ bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
+ brightness = 0;
+
+ gpiod_set_value_cansleep(gbl->gpiod, brightness);
+
+ return 0;
+}
+
+static int gpio_backlight_check_fb(struct backlight_device *bl,
+ struct fb_info *info)
+{
+ struct gpio_backlight *gbl = bl_get_data(bl);
+
+ return gbl->fbdev == NULL || gbl->fbdev == info->dev;
+}
+
+static const struct backlight_ops gpio_backlight_ops = {
+ .options = BL_CORE_SUSPENDRESUME,
+ .update_status = gpio_backlight_update_status,
+ .check_fb = gpio_backlight_check_fb,
+};
+
+static int gpio_backlight_probe_dt(struct platform_device *pdev,
+ struct gpio_backlight *gbl)
+{
+ struct device *dev = &pdev->dev;
+ struct device_node *np = dev->of_node;
+ enum gpiod_flags flags;
+ int ret;
+
+ gbl->def_value = of_property_read_bool(np, "default-on");
+ flags = gbl->def_value ? GPIOD_OUT_HIGH : GPIOD_OUT_LOW;
+
+ gbl->gpiod = devm_gpiod_get(dev, NULL, flags);
+ if (IS_ERR(gbl->gpiod)) {
+ ret = PTR_ERR(gbl->gpiod);
+
+ if (ret != -EPROBE_DEFER) {
+ dev_err(dev,
+ "Error: The gpios parameter is missing or invalid.\n");
+ }
+ return ret;
+ }
+
+ return 0;
+}
+
+static int gpio_backlight_probe(struct platform_device *pdev)
+{
+ struct gpio_backlight_platform_data *pdata =
+ dev_get_platdata(&pdev->dev);
+ struct backlight_properties props;
+ struct backlight_device *bl;
+ struct gpio_backlight *gbl;
+ struct device_node *np = pdev->dev.of_node;
+ int ret;
+
+ if (!pdata && !np) {
+ dev_err(&pdev->dev,
+ "failed to find platform data or device tree node.\n");
+ return -ENODEV;
+ }
+
+ gbl = devm_kzalloc(&pdev->dev, sizeof(*gbl), GFP_KERNEL);
+ if (gbl == NULL)
+ return -ENOMEM;
+
+ gbl->dev = &pdev->dev;
+
+ if (np) {
+ ret = gpio_backlight_probe_dt(pdev, gbl);
+ if (ret)
+ return ret;
+ } else {
+ /*
+ * Legacy platform data GPIO retrieveal. Do not expand
+ * the use of this code path, currently only used by one
+ * SH board.
+ */
+ unsigned long flags = GPIOF_DIR_OUT;
+
+ gbl->fbdev = pdata->fbdev;
+ gbl->def_value = pdata->def_value;
+ flags |= gbl->def_value ? GPIOF_INIT_HIGH : GPIOF_INIT_LOW;
+
+ ret = devm_gpio_request_one(gbl->dev, pdata->gpio, flags,
+ pdata ? pdata->name : "backlight");
+ if (ret < 0) {
+ dev_err(&pdev->dev, "unable to request GPIO\n");
+ return ret;
+ }
+ gbl->gpiod = gpio_to_desc(pdata->gpio);
+ if (!gbl->gpiod)
+ return -EINVAL;
+ }
+
+ memset(&props, 0, sizeof(props));
+ props.type = BACKLIGHT_RAW;
+ props.max_brightness = 1;
+ bl = devm_backlight_device_register(&pdev->dev, dev_name(&pdev->dev),
+ &pdev->dev, gbl, &gpio_backlight_ops,
+ &props);
+ if (IS_ERR(bl)) {
+ dev_err(&pdev->dev, "failed to register backlight\n");
+ return PTR_ERR(bl);
+ }
+
+ bl->props.brightness = gbl->def_value;
+ backlight_update_status(bl);
+
+ platform_set_drvdata(pdev, bl);
+ return 0;
+}
+
+#ifdef CONFIG_OF
+static struct of_device_id gpio_backlight_of_match[] = {
+ { .compatible = "gpio-backlight" },
+ { /* sentinel */ }
+};
+
+MODULE_DEVICE_TABLE(of, gpio_backlight_of_match);
+#endif
+
+static struct platform_driver gpio_backlight_driver = {
+ .driver = {
+ .name = "gpio-backlight",
+ .of_match_table = of_match_ptr(gpio_backlight_of_match),
+ },
+ .probe = gpio_backlight_probe,
+};
+
+module_platform_driver(gpio_backlight_driver);
+
+MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>");
+MODULE_DESCRIPTION("GPIO-based Backlight Driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:gpio-backlight");