Re: [PATCH v6 4/4] backlight: add led-backlight driver

On Tue, Sep 10, 2019 at 03:27:34PM +0200, Jean-Jacques Hiblot wrote:

From: Tomi Valkeinen tomi.valkeinen@ti.com

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. Multiple LEDs can be used for a single backlight.

Signed-off-by: Tomi Valkeinen tomi.valkeinen@ti.com Signed-off-by: Jean-Jacques Hiblot jjhiblot@ti.com Acked-by: Pavel Machek pavel@ucw.cz

Reviewed-by: Daniel Thompson daniel.thompson@linaro.org

---

drivers/video/backlight/Kconfig | 7 + drivers/video/backlight/Makefile | 1 + drivers/video/backlight/led_bl.c | 260 +++++++++++++++++++++++++++++++ 3 files changed, 268 insertions(+) create mode 100644 drivers/video/backlight/led_bl.c

diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig index 8b081d61773e..585a1787618c 100644 --- a/drivers/video/backlight/Kconfig +++ b/drivers/video/backlight/Kconfig @@ -458,6 +458,13 @@ config BACKLIGHT_RAVE_SP help Support for backlight control on RAVE SP device.

+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

endmenu diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile index 63c507c07437..2a67642966a5 100644 --- a/drivers/video/backlight/Makefile +++ b/drivers/video/backlight/Makefile @@ -57,3 +57,4 @@ obj-$(CONFIG_BACKLIGHT_TPS65217) += tps65217_bl.o obj-$(CONFIG_BACKLIGHT_WM831X) += wm831x_bl.o obj-$(CONFIG_BACKLIGHT_ARCXCNN) += arcxcnn_bl.o obj-$(CONFIG_BACKLIGHT_RAVE_SP) += rave-sp-backlight.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..6044390d8b88 --- /dev/null +++ b/drivers/video/backlight/led_bl.c @@ -0,0 +1,260 @@ +// SPDX-License-Identifier: GPL-2.0 +/*

• • Copyright (C) 2015-2019 Texas Instruments Incorporated - http://www.ti.com/
• • Author: Tomi Valkeinen tomi.valkeinen@ti.com
• • Based on pwm_bl.c
• */

+#include <linux/backlight.h> +#include <linux/leds.h> +#include <linux/module.h> +#include <linux/platform_device.h>

+struct led_bl_data {

• struct device *dev;
• struct backlight_device *bl_dev;
• struct led_classdev **leds;
• bool enabled;
• int nb_leds;
• unsigned int *levels;
• unsigned int default_brightness;
• unsigned int max_brightness;

+};

+static void led_bl_set_brightness(struct led_bl_data *priv, int level) +{

• int i;
• int bkl_brightness;
• if (priv->levels)

• bkl_brightness = priv->levels[level];
  

• else

• bkl_brightness = level;
  

• for (i = 0; i < priv->nb_leds; i++)

• led_set_brightness(priv->leds[i], bkl_brightness);
  

• priv->enabled = true;

+}

+static void led_bl_power_off(struct led_bl_data *priv) +{

• int i;
• if (!priv->enabled)

• return;
  

• for (i = 0; i < priv->nb_leds; i++)

• led_set_brightness(priv->leds[i], LED_OFF);
  

• 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_get_leds(struct device *dev,

• 	   struct led_bl_data *priv)
  

+{

• int i, nb_leds, ret;
• struct device_node *node = dev->of_node;
• struct led_classdev **leds;
• unsigned int max_brightness;
• unsigned int default_brightness;
• ret = of_count_phandle_with_args(node, "leds", NULL);
• if (ret < 0) {

• dev_err(dev, "Unable to get led count\n");
  

• return -EINVAL;
  

• }
• nb_leds = ret;
• if (nb_leds < 1) {

• dev_err(dev, "At least one LED must be specified!\n");
  

• return -EINVAL;
  

• }
• leds = devm_kzalloc(dev, sizeof(struct led_classdev *) * nb_leds,

• 	    GFP_KERNEL);
  

• if (!leds)

• return -ENOMEM;
  

• for (i = 0; i < nb_leds; i++) {

• leds[i] = devm_led_get(dev, i);
  

• if (IS_ERR(leds[i]))
  

• 	return PTR_ERR(leds[i]);
  

• }
• /* check that the LEDs all have the same brightness range */
• max_brightness = leds[0]->max_brightness;
• for (i = 1; i < nb_leds; i++) {

• if (max_brightness != leds[i]->max_brightness) {
  

• 	dev_err(dev, "LEDs must have identical ranges\n");
  

• 	return -EINVAL;
  

• }
  

• }
• /* get the default brightness from the first LED from the list */
• default_brightness = leds[0]->brightness;
• priv->nb_leds = nb_leds;
• priv->leds = leds;
• priv->max_brightness = max_brightness;
• priv->default_brightness = default_brightness;
• return 0;

+}

+static int led_bl_parse_levels(struct device *dev,

• 	   struct led_bl_data *priv)
  

+{

• struct device_node *node = dev->of_node;
• int num_levels;
• u32 value;
• int ret;
• if (!node)

• return -ENODEV;
  

• num_levels = of_property_count_u32_elems(node, "brightness-levels");
• if (num_levels > 1) {

• int i;
  

• unsigned int db;
  

• u32 *levels = NULL;
  

• 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)
  

• 	return ret;
  

• /*
  

•  * Try to map actual LED brightness to backlight brightness
  

•  * level
  

•  */
  

• db = priv->default_brightness;
  

• for (i = 0 ; i < num_levels; i++) {
  

• 	if ((i && db > levels[i-1]) && db <= levels[i])
  

• 		break;
  

• }
  

• priv->default_brightness = i;
  

• priv->max_brightness = num_levels - 1;
  

• priv->levels = levels;
  

• } else if (num_levels >= 0)

• dev_warn(dev, "Not enough levels defined\n");
  

• ret = of_property_read_u32(node, "default-brightness-level", &value);
• if (!ret && value <= priv->max_brightness)

• priv->default_brightness = value;
  

• else if (!ret && value > priv->max_brightness)

• dev_warn(dev, "Invalid default brightness. Ignoring it\n");
  

• return 0;

+}

+static int led_bl_probe(struct platform_device *pdev) +{

• struct backlight_properties props;
• struct led_bl_data *priv;
• int ret, i;
• 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_get_leds(&pdev->dev, priv);
• if (ret)

• return ret;
  

• ret = led_bl_parse_levels(&pdev->dev, priv);
• if (ret < 0) {

• dev_err(&pdev->dev, "Failed to parse DT data\n");
  

• return ret;
  

• }
• memset(&props, 0, sizeof(struct backlight_properties));
• props.type = BACKLIGHT_RAW;
• props.max_brightness = priv->max_brightness;
• props.brightness = priv->default_brightness;
• props.power = (priv->default_brightness > 0) ? FB_BLANK_POWERDOWN :

•       FB_BLANK_UNBLANK;
  

• 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");
  

• return PTR_ERR(priv->bl_dev);
  

• }
• for (i = 0; i < priv->nb_leds; i++)

• led_sysfs_disable(priv->leds[i]);
  

• backlight_update_status(priv->bl_dev);
• return 0;

+}

+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;
• int i;
• backlight_device_unregister(bl);
• led_bl_power_off(priv);
• for (i = 0; i < priv->nb_leds; i++)

• led_sysfs_enable(priv->leds[i]);
  

• 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");

2.17.1