[PATCH 12/22] video: backlight: Add GPIO Backlight driver.
Denis Carikli
denis at eukrea.com
Mon Jul 15 10:56:57 EDT 2013
This initial driver uses and depends on DT bindings.
Signed-off-by: Denis Carikli <denis at eukrea.com>
---
.../bindings/video/backlight/gpio-backlight.txt | 18 ++
drivers/video/backlight/Kconfig | 7 +
drivers/video/backlight/Makefile | 1 +
drivers/video/backlight/gpio_bl.c | 226 ++++++++++++++++++++
4 files changed, 252 insertions(+)
create mode 100644 Documentation/devicetree/bindings/video/backlight/gpio-backlight.txt
create mode 100644 drivers/video/backlight/gpio_bl.c
diff --git a/Documentation/devicetree/bindings/video/backlight/gpio-backlight.txt b/Documentation/devicetree/bindings/video/backlight/gpio-backlight.txt
new file mode 100644
index 0000000..362dd40
--- /dev/null
+++ b/Documentation/devicetree/bindings/video/backlight/gpio-backlight.txt
@@ -0,0 +1,18 @@
+gpio-backlight bindings
+
+Required properties:
+ - compatible: "gpio-backlight"
+ - gpios: describes the gpio that is used for enabling/disabling the backlight
+ (see GPIO binding[0] for more details).
+ - default-brightness-level: the default brightness level (can be 0(off) or
+ 1(on) since GPIOs only support theses levels).
+
+[0]: Documentation/devicetree/bindings/gpio/gpio.txt
+
+Example:
+
+ backlight {
+ compatible = "gpio-backlight";
+ gpios = <&gpio3 4 0>;
+ default-brightness-level = <1>;
+ };
diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index d5ab658..70e7706 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -207,6 +207,13 @@ config BACKLIGHT_GENERIC
known as the Corgi backlight driver. If you have a Sharp Zaurus
SL-C7xx, SL-Cxx00 or SL-6000x say y.
+config BACKLIGHT_GPIO
+ tristate "GPIO Backlight Driver"
+ depends on OF && GPIOLIB
+ help
+ If you have a GPIO backlight and that you use the device tree
+ for booting, say y to enable the GPIO backlight driver.
+
config BACKLIGHT_LM3533
tristate "Backlight Driver for LM3533"
depends on BACKLIGHT_CLASS_DEVICE
diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
index 92711fe..8cde337 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -32,6 +32,7 @@ obj-$(CONFIG_BACKLIGHT_DA903X) += da903x_bl.o
obj-$(CONFIG_BACKLIGHT_DA9052) += da9052_bl.o
obj-$(CONFIG_BACKLIGHT_EP93XX) += ep93xx_bl.o
obj-$(CONFIG_BACKLIGHT_GENERIC) += generic_bl.o
+obj-$(CONFIG_BACKLIGHT_GPIO) += gpio_bl.o
obj-$(CONFIG_BACKLIGHT_HP680) += hp680_bl.o
obj-$(CONFIG_BACKLIGHT_HP700) += jornada720_bl.o
obj-$(CONFIG_BACKLIGHT_LM3533) += lm3533_bl.o
diff --git a/drivers/video/backlight/gpio_bl.c b/drivers/video/backlight/gpio_bl.c
new file mode 100644
index 0000000..76b9c99
--- /dev/null
+++ b/drivers/video/backlight/gpio_bl.c
@@ -0,0 +1,226 @@
+/*
+ * drivers/video/backlight/gpio_bl.c
+ *
+ * simple GPIO based backlight control.
+ *
+ * Copyright 2013 Eukréa Electromatique <denis at eukrea.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Based on drivers/video/backlight/pwm_bl.c
+ */
+
+#include <linux/backlight.h>
+#include <linux/fb.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_gpio.h>
+#include <linux/platform_device.h>
+
+struct gpio_bl_data {
+ unsigned gpio;
+ u32 dft_brightness;
+ u32 active_low; /* 1 if active_low, 0 otherwise */
+};
+
+static int gpio_backlight_update_status(struct backlight_device *bl)
+{
+ struct gpio_bl_data *gb = 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_FBBLANK)
+ brightness = 0;
+
+ return gpio_direction_output(gb->gpio,
+ brightness ?
+ !gb->active_low : gb->active_low);
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int gpio_backlight_suspend(struct device *dev)
+{
+ struct backlight_device *bl = dev_get_drvdata(dev);
+ struct gpio_bl_data *gb = bl_get_data(bl);
+
+ /* Power down the backlight */
+ return gpio_direction_output(gb->gpio, gb->active_low);
+}
+
+static int gpio_backlight_resume(struct device *dev)
+{
+ struct backlight_device *bl = dev_get_drvdata(dev);
+
+ backlight_update_status(bl);
+
+ return 0;
+}
+#endif
+
+static int gpio_backlight_get_brightness(struct backlight_device *bl)
+{
+ return bl->props.brightness;
+}
+
+static const struct backlight_ops gpio_backlight_ops = {
+ .update_status = gpio_backlight_update_status,
+ .get_brightness = gpio_backlight_get_brightness,
+};
+
+static int gpio_backlight_remove(struct platform_device *pdev)
+{
+ struct backlight_device *bl = platform_get_drvdata(pdev);
+ struct gpio_bl_data *gb = bl_get_data(bl);
+ int ret;
+
+ backlight_device_unregister(bl);
+
+ /* Power down the backlight */
+ ret = gpio_direction_output(gb->gpio, gb->active_low);
+ if (ret < 0)
+ dev_err(&pdev->dev, "Failled to set GPIO %u to output direction\n",
+ gb->gpio);
+
+ return 0;
+}
+
+static int gpio_backlight_probe(struct platform_device *pdev)
+{
+ struct backlight_properties props;
+ struct backlight_device *bl;
+ struct gpio_bl_data *gb;
+ struct device_node *np = pdev->dev.of_node;
+ enum of_gpio_flags gpio_flags;
+ int ret = 0;
+
+ dev_info(&pdev->dev, "Initializing.\n");
+
+ gb = devm_kzalloc(&pdev->dev, sizeof(*gb), GFP_KERNEL);
+ if (!gb) {
+ dev_err(&pdev->dev, "No memory for gpio_bl_data.\n");
+ return -ENOMEM;
+ }
+
+ ret = of_property_read_u32(np, "default-brightness-level",
+ &gb->dft_brightness);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "Error: default-brightness-level is a required parameter.\n");
+ goto err_free_pdata;
+ }
+
+ if (gb->dft_brightness < 0 || gb->dft_brightness > 1) {
+ dev_err(&pdev->dev, "Error: Invalid default-brightness-level value."
+ " Its value can be either 0(off) or 1(on).\n");
+ goto err_free_pdata;
+ }
+
+ ret = of_property_read_u32(np, "active-level", &gb->active_low);
+ /* By default, the GPIO activating the backlight is active high. */
+ if (ret < 0)
+ gb->active_low = 0;
+ else
+ if (gb->active_low < 0 || gb->active_low > 1) {
+ dev_err(&pdev->dev, "Error: Invalid active-level value."
+ " Its value can be either 0(active low)"
+ "or 1(active high).\n");
+ }
+
+ gb->gpio = of_get_gpio_flags(np, 0, &gpio_flags);
+ gb->active_low = gpio_flags & OF_GPIO_ACTIVE_LOW;
+ if (gb->gpio == -EPROBE_DEFER) {
+ ret = ERR_PTR(-EPROBE_DEFER);
+ goto err_free_pdata;
+ } else if (gb->gpio < 0) {
+ ret = gb->gpio;
+ dev_err(&pdev->dev, "Error: gpios is a required parameter.\n");
+ goto err_free_pdata;
+ }
+
+ /* Request the backlight gpio */
+ ret = gpio_request(gb->gpio, "LCDBL");
+ if (ret < 0) {
+ dev_err(&pdev->dev, "Failled to request LCD Backlight"
+ " GPIO %u.\n", gb->gpio);
+ goto err_free_pdata;
+ }
+ /* If the default brightness is 1, enable the backlight,
+ * else power it down */
+ ret = gpio_direction_output(gb->gpio,
+ gb->dft_brightness ?
+ !gb->active_low : gb->active_low);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "The LCD GPIO %u failed to "
+ "%s the backlight.\n",
+ gb->gpio,
+ gb->dft_brightness ? "enable" : "disable");
+ goto err_free_pdata;
+ }
+
+ dev_info(&pdev->dev, "The backlight was %s by the GPIO %u "
+ "which is %s.\n",
+ gb->dft_brightness ? "Enabled" : "Disabled",
+ gb->gpio,
+ gb->active_low ? "active low" : "active high");
+
+ memset(&props, 0, sizeof(struct backlight_properties));
+ props.type = BACKLIGHT_RAW;
+ props.max_brightness = 1; /* A GPIO can only be at level 0 or 1 */
+
+ bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, gb,
+ &gpio_backlight_ops, &props);
+ if (IS_ERR(bl)) {
+ dev_err(&pdev->dev, "Failed to register backlight\n");
+ ret = PTR_ERR(bl);
+ goto err_free_pdata;
+ }
+
+ bl->props.brightness = 1;
+ backlight_update_status(bl);
+ platform_set_drvdata(pdev, bl);
+
+ dev_info(&pdev->dev, "Initialized.\n");
+
+ return 0;
+
+err_free_pdata:
+ devm_kfree(&pdev->dev, bl);
+ return ret;
+}
+
+MODULE_DEVICE_TABLE(of, gpio_backlight_of_match);
+static SIMPLE_DEV_PM_OPS(gpio_backlight_pm_ops, gpio_backlight_suspend,
+ gpio_backlight_resume);
+
+static struct of_device_id gpio_backlight_of_match[] = {
+ { .compatible = "gpio-backlight" },
+ { /* sentinel */ }
+};
+
+static struct platform_driver gpio_backlight_driver = {
+ .driver = {
+ .name = "gpio-backlight",
+ .owner = THIS_MODULE,
+ .pm = &gpio_backlight_pm_ops,
+ .of_match_table = of_match_ptr(gpio_backlight_of_match),
+ },
+ .probe = gpio_backlight_probe,
+ .remove = gpio_backlight_remove,
+};
+
+module_platform_driver(gpio_backlight_driver);
+
+MODULE_DESCRIPTION("GPIO based Backlight Driver");
+MODULE_LICENSE("GPLv2");
+MODULE_ALIAS("platform:gpio-backlight");
--
1.7.9.5
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