1 files changed, 128 insertions, 0 deletions
diff --git a/drivers/video/backlight/gpio_backlight.c b/drivers/video/backlight/gpio_backlight.c
new file mode 100644
index 0000000000..d28c30b2a3
--- /dev/null
+++ b/drivers/video/backlight/gpio_backlight.c
@@ -0,0 +1,128 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * gpio_backlight.c - Simple GPIO-controlled backlight
+ */
+
+#include <linux/backlight.h>
+#include <linux/err.h>
+#include <linux/fb.h>
+#include <linux/gpio/consumer.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_data/gpio_backlight.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/slab.h>
+
+struct gpio_backlight {
+	struct device *dev;
+	struct gpio_desc *gpiod;
+};
+
+static int gpio_backlight_update_status(struct backlight_device *bl)
+{
+	struct gpio_backlight *gbl = bl_get_data(bl);
+
+	gpiod_set_value_cansleep(gbl->gpiod, backlight_get_brightness(bl));
+
+	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->dev || gbl->dev == info->device;
+}
+
+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(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct gpio_backlight_platform_data *pdata = dev_get_platdata(dev);
+	struct device_node *of_node = dev->of_node;
+	struct backlight_properties props;
+	struct backlight_device *bl;
+	struct gpio_backlight *gbl;
+	int ret, init_brightness, def_value;
+
+	gbl = devm_kzalloc(dev, sizeof(*gbl), GFP_KERNEL);
+	if (gbl == NULL)
+		return -ENOMEM;
+
+	if (pdata)
+		gbl->dev = pdata->dev;
+
+	def_value = device_property_read_bool(dev, "default-on");
+
+	gbl->gpiod = devm_gpiod_get(dev, NULL, GPIOD_ASIS);
+	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;
+	}
+
+	memset(&props, 0, sizeof(props));
+	props.type = BACKLIGHT_RAW;
+	props.max_brightness = 1;
+	bl = devm_backlight_device_register(dev, dev_name(dev), dev, gbl,
+					    &gpio_backlight_ops, &props);
+	if (IS_ERR(bl)) {
+		dev_err(dev, "failed to register backlight\n");
+		return PTR_ERR(bl);
+	}
+
+	/* Set the initial power state */
+	if (!of_node || !of_node->phandle)
+		/* Not booted with device tree or no phandle link to the node */
+		bl->props.power = def_value ? FB_BLANK_UNBLANK
+					    : FB_BLANK_POWERDOWN;
+	else if (gpiod_get_value_cansleep(gbl->gpiod) == 0)
+		bl->props.power = FB_BLANK_POWERDOWN;
+	else
+		bl->props.power = FB_BLANK_UNBLANK;
+
+	bl->props.brightness = 1;
+
+	init_brightness = backlight_get_brightness(bl);
+	ret = gpiod_direction_output(gbl->gpiod, init_brightness);
+	if (ret) {
+		dev_err(dev, "failed to set initial brightness\n");
+		return ret;
+	}
+
+	platform_set_drvdata(pdev, bl);
+	return 0;
+}
+
+static struct of_device_id gpio_backlight_of_match[] = {
+	{ .compatible = "gpio-backlight" },
+	{ /* sentinel */ }
+};
+
+MODULE_DEVICE_TABLE(of, gpio_backlight_of_match);
+
+static struct platform_driver gpio_backlight_driver = {
+	.driver		= {
+		.name		= "gpio-backlight",
+		.of_match_table = 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");