Jingoo?
On Wed, 30 Sep 2015, Tomi Valkeinen wrote:
> This patch adds a led-backlight driver (led_bl), which is similar to
> pwm_bl except the driver uses a LED class driver to adjust the
> brightness in the HW.
>
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxx>
> ---
> drivers/video/backlight/Kconfig | 7 ++
> drivers/video/backlight/Makefile | 1 +
> drivers/video/backlight/led_bl.c | 246 +++++++++++++++++++++++++++++++++++++++
> 3 files changed, 254 insertions(+)
> create mode 100644 drivers/video/backlight/led_bl.c
>
> diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
> index 0505b796d743..d1336196aba2 100644
> --- a/drivers/video/backlight/Kconfig
> +++ b/drivers/video/backlight/Kconfig
> @@ -453,6 +453,13 @@ config BACKLIGHT_BD6107
> help
> If you have a Rohm BD6107 say Y to enable the backlight driver.
>
> +config BACKLIGHT_LED
> + tristate "Generic LED based Backlight Driver"
> + depends on LEDS_CLASS && OF
> + help
> + If you have a LCD backlight adjustable by LED class driver, say Y
> + to enable this driver.
> +
> endif # BACKLIGHT_CLASS_DEVICE
>
> endif # BACKLIGHT_LCD_SUPPORT
> diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
> index d67073f9d421..ecd321daee21 100644
> --- a/drivers/video/backlight/Makefile
> +++ b/drivers/video/backlight/Makefile
> @@ -54,3 +54,4 @@ obj-$(CONFIG_BACKLIGHT_SKY81452) += sky81452-backlight.o
> obj-$(CONFIG_BACKLIGHT_TOSA) += tosa_bl.o
> obj-$(CONFIG_BACKLIGHT_TPS65217) += tps65217_bl.o
> obj-$(CONFIG_BACKLIGHT_WM831X) += wm831x_bl.o
> +obj-$(CONFIG_BACKLIGHT_LED) += led_bl.o
> diff --git a/drivers/video/backlight/led_bl.c b/drivers/video/backlight/led_bl.c
> new file mode 100644
> index 000000000000..1befc8ce5964
> --- /dev/null
> +++ b/drivers/video/backlight/led_bl.c
> @@ -0,0 +1,246 @@
> +/*
> + * Copyright 2015 Texas Instruments
> + *
> + * Author: Tomi Valkeinen <tomi.valkeinen@xxxxxx>
> + *
> + * Based on pwm_bl.c
> + *
> + * 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; version 2 of the License.
> + */
> +#include <linux/backlight.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/leds.h>
> +#include <linux/of_leds.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/slab.h>
> +
> +struct led_bl_data {
> + struct device *dev;
> + struct backlight_device *bl_dev;
> +
> + unsigned int *levels;
> + bool enabled;
> + struct regulator *power_supply;
> + struct gpio_desc *enable_gpio;
> +
> + struct led_classdev *led_cdev;
> +
> + unsigned int max_brightness;
> + unsigned int default_brightness;
> +};
> +
> +static void led_bl_set_brightness(struct led_bl_data *priv, int brightness)
> +{
> + int err;
> +
> + if (!priv->enabled) {
> + if (priv->power_supply) {
> + err = regulator_enable(priv->power_supply);
> +
> + if (err < 0)
> + dev_err(priv->dev,
> + "failed to enable power supply\n");
> + }
> +
> + if (priv->enable_gpio)
> + gpiod_set_value_cansleep(priv->enable_gpio, 1);
> + }
> +
> + led_set_brightness(priv->led_cdev, priv->levels[brightness]);
> +
> + priv->enabled = true;
> +}
> +
> +static void led_bl_power_off(struct led_bl_data *priv)
> +{
> + if (!priv->enabled)
> + return;
> +
> + led_set_brightness(priv->led_cdev, LED_OFF);
> +
> + if (priv->enable_gpio)
> + gpiod_set_value_cansleep(priv->enable_gpio, 0);
> +
> + if (priv->power_supply)
> + regulator_disable(priv->power_supply);
> +
> + priv->enabled = false;
> +}
> +
> +static int led_bl_update_status(struct backlight_device *bl)
> +{
> + struct led_bl_data *priv = 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;
> +
> + if (brightness > 0)
> + led_bl_set_brightness(priv, brightness);
> + else
> + led_bl_power_off(priv);
> +
> + return 0;
> +}
> +
> +static const struct backlight_ops led_bl_ops = {
> + .update_status = led_bl_update_status,
> +};
> +
> +static int led_bl_parse_dt(struct device *dev,
> + struct led_bl_data *priv)
> +{
> + struct device_node *node = dev->of_node;
> + int num_levels;
> + u32 *levels;
> + u32 value;
> + int ret;
> +
> + if (!node)
> + return -ENODEV;
> +
> + num_levels = of_property_count_u32_elems(node, "brightness-levels");
> + if (num_levels < 0) {
> + dev_err(dev, "failed to find 'brightness-levels'\n");
> + return num_levels;
> + }
> +
> + levels = devm_kzalloc(dev, sizeof(u32) * num_levels, GFP_KERNEL);
> + if (!levels)
> + return -ENOMEM;
> +
> + ret = of_property_read_u32_array(node, "brightness-levels",
> + levels,
> + num_levels);
> + if (ret < 0) {
> + dev_err(dev, "failed to parse 'brightness-levels'\n");
> + return ret;
> + }
> +
> + ret = of_property_read_u32(node, "default-brightness-level", &value);
> + if (ret < 0) {
> + dev_err(dev, "failed to parse 'default-brightness-level'\n");
> + return ret;
> + }
> +
> + if (value >= num_levels) {
> + dev_err(dev, "invalid default-brightness-level\n");
> + return -EINVAL;
> + }
> +
> + priv->levels = levels;
> + priv->max_brightness = num_levels - 1;
> + priv->default_brightness = value;
> +
> + priv->led_cdev = of_led_get(node);
> + if (IS_ERR(priv->led_cdev)) {
> + dev_err(dev, "failed to get LED device\n");
> + return PTR_ERR(priv->led_cdev);
> + }
> +
> + return 0;
> +}
> +
> +static int led_bl_probe(struct platform_device *pdev)
> +{
> + struct backlight_properties props;
> + struct led_bl_data *priv;
> + int ret;
> +
> + priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
> + if (!priv)
> + return -ENOMEM;
> +
> + platform_set_drvdata(pdev, priv);
> +
> + priv->dev = &pdev->dev;
> +
> + ret = led_bl_parse_dt(&pdev->dev, priv);
> + if (ret < 0) {
> + dev_err(&pdev->dev, "failed to parse DT data\n");
> + return ret;
> + }
> +
> + priv->enable_gpio = devm_gpiod_get_optional(&pdev->dev, "enable",
> + GPIOD_OUT_LOW);
> + if (IS_ERR(priv->enable_gpio)) {
> + ret = PTR_ERR(priv->enable_gpio);
> + goto err;
> + }
> +
> + priv->power_supply = devm_regulator_get_optional(&pdev->dev, "power");
> + if (IS_ERR(priv->power_supply)) {
> + ret = PTR_ERR(priv->power_supply);
> +
> + if (ret == -ENODEV) {
> + priv->power_supply = NULL;
> + } else {
> + ret = PTR_ERR(priv->power_supply);
> + goto err;
> + }
> + }
> +
> + memset(&props, 0, sizeof(struct backlight_properties));
> + props.type = BACKLIGHT_RAW;
> + props.max_brightness = priv->max_brightness;
> + priv->bl_dev = backlight_device_register(dev_name(&pdev->dev),
> + &pdev->dev, priv, &led_bl_ops, &props);
> + if (IS_ERR(priv->bl_dev)) {
> + dev_err(&pdev->dev, "failed to register backlight\n");
> + ret = PTR_ERR(priv->bl_dev);
> + goto err;
> + }
> +
> + priv->bl_dev->props.brightness = priv->default_brightness;
> + backlight_update_status(priv->bl_dev);
> +
> + return 0;
> +
> +err:
> + if (priv->led_cdev)
> + led_put(priv->led_cdev);
> +
> + return ret;
> +}
> +
> +static int led_bl_remove(struct platform_device *pdev)
> +{
> + struct led_bl_data *priv = platform_get_drvdata(pdev);
> + struct backlight_device *bl = priv->bl_dev;
> +
> + backlight_device_unregister(bl);
> +
> + led_bl_power_off(priv);
> +
> + led_put(priv->led_cdev);
> +
> + return 0;
> +}
> +
> +static const struct of_device_id led_bl_of_match[] = {
> + { .compatible = "led-backlight" },
> + { }
> +};
> +
> +MODULE_DEVICE_TABLE(of, led_bl_of_match);
> +
> +static struct platform_driver led_bl_driver = {
> + .driver = {
> + .name = "led-backlight",
> + .of_match_table = of_match_ptr(led_bl_of_match),
> + },
> + .probe = led_bl_probe,
> + .remove = led_bl_remove,
> +};
> +
> +module_platform_driver(led_bl_driver);
> +
> +MODULE_DESCRIPTION("LED based Backlight Driver");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:led-backlight");
--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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