Initial import

1 files changed, 164 insertions, 0 deletions

diff --git a/drivers/video/backlight/gpio_backlight.c b/drivers/video/backlight/gpio_backlight.c
new file mode 100644
index 000000000..439feb238
--- /dev/null
+++ b/drivers/video/backlight/gpio_backlight.c
@@ -0,0 +1,164 @@
+/*
+ * 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>
+#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;
+
+	int gpio;
+	int active;
+	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;
+
+	gpio_set_value_cansleep(gbl->gpio,
+				brightness ? gbl->active : !gbl->active);
+
+	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_node *np = pdev->dev.of_node;
+	enum of_gpio_flags gpio_flags;
+
+	gbl->gpio = of_get_gpio_flags(np, 0, &gpio_flags);
+
+	if (!gpio_is_valid(gbl->gpio)) {
+		if (gbl->gpio != -EPROBE_DEFER) {
+			dev_err(&pdev->dev,
+				"Error: The gpios parameter is missing or invalid.\n");
+		}
+		return gbl->gpio;
+	}
+
+	gbl->active = (gpio_flags & OF_GPIO_ACTIVE_LOW) ? 0 : 1;
+
+	gbl->def_value = of_property_read_bool(np, "default-on");
+
+	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 {
+		gbl->fbdev = pdata->fbdev;
+		gbl->gpio = pdata->gpio;
+		gbl->active = pdata->active_low ? 0 : 1;
+		gbl->def_value = pdata->def_value;
+	}
+
+	ret = devm_gpio_request_one(gbl->dev, gbl->gpio, GPIOF_DIR_OUT |
+				    (gbl->active ? GPIOF_INIT_LOW
+						 : GPIOF_INIT_HIGH),
+				    pdata ? pdata->name : "backlight");
+	if (ret < 0) {
+		dev_err(&pdev->dev, "unable to request GPIO\n");
+		return ret;
+	}
+
+	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 */ }
+};
+#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");