From: Tomi Valkeinen tomi.valkeinen@ti.com

This patch adds basic support for a kernel driver to get a LED device. This will be used by the led-backlight driver.

Only OF version is implemented for now, and the behavior is similar to PWM's of_pwm_get() and pwm_put().

Signed-off-by: Tomi Valkeinen tomi.valkeinen@ti.com Signed-off-by: Jean-Jacques Hiblot jjhiblot@ti.com --- drivers/leds/led-class.c | 50 ++++++++++++++++++++++++++++++++++++++++ include/linux/leds.h | 4 ++++ 2 files changed, 54 insertions(+)

diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c index cadd43c30d50..9f48798a713d 100644 --- a/drivers/leds/led-class.c +++ b/drivers/leds/led-class.c @@ -18,6 +18,7 @@ #include <linux/spinlock.h> #include <linux/timer.h> #include <uapi/linux/uleds.h> +#include <linux/of.h> #include "leds.h"

static struct class *leds_class; @@ -213,6 +214,55 @@ static int led_resume(struct device *dev)

static SIMPLE_DEV_PM_OPS(leds_class_dev_pm_ops, led_suspend, led_resume);

+static int led_match_led_node(struct device *led_dev, const void *data) +{ + return led_dev->of_node == data; +} + +/** + * of_led_get() - request a LED device via the LED framework + * @np: device node to get the LED device from + * @index: the index of the LED + * + * Returns the LED device parsed from the phandle specified in the "leds" + * property of a device tree node or a negative error-code on failure. + */ +struct led_classdev *of_led_get(struct device_node *np, int index) +{ + struct device *led_dev; + struct led_classdev *led_cdev; + struct device_node *led_node; + + led_node = of_parse_phandle(np, "leds", index); + if (!led_node) + return ERR_PTR(-ENOENT); + + led_dev = class_find_device(leds_class, NULL, led_node, + led_match_led_node); + of_node_put(led_node); + + if (!led_dev) + return ERR_PTR(-EPROBE_DEFER); + + led_cdev = dev_get_drvdata(led_dev); + + if (!try_module_get(led_cdev->dev->parent->driver->owner)) + return ERR_PTR(-ENODEV); + + return led_cdev; +} +EXPORT_SYMBOL_GPL(of_led_get); + +/** + * led_put() - release a LED device + * @led_cdev: LED device + */ +void led_put(struct led_classdev *led_cdev) +{ + module_put(led_cdev->dev->parent->driver->owner); +} +EXPORT_SYMBOL_GPL(led_put); + static int match_name(struct device *dev, const void *data) { if (!dev_name(dev)) diff --git a/include/linux/leds.h b/include/linux/leds.h index bee8e3f8dddd..0a71c7cdd191 100644 --- a/include/linux/leds.h +++ b/include/linux/leds.h @@ -19,6 +19,7 @@

struct device; struct led_pattern; +struct device_node; /* * LED Core */ @@ -145,6 +146,9 @@ extern void devm_led_classdev_unregister(struct device *parent, extern void led_classdev_suspend(struct led_classdev *led_cdev); extern void led_classdev_resume(struct led_classdev *led_cdev);

+extern struct led_classdev *of_led_get(struct device_node *np, int index); +extern void led_put(struct led_classdev *led_cdev); + /** * led_blink_set - set blinking with software fallback * @led_cdev: the LED to start blinking

If the LED is acquired by a consumer device with devm_led_get(), it is automatically released when the device is detached.

Signed-off-by: Jean-Jacques Hiblot jjhiblot@ti.com Acked-by: Pavel Machek pavel@ucw.cz --- drivers/leds/led-class.c | 42 ++++++++++++++++++++++++++++++++++++++++ include/linux/leds.h | 2 ++ 2 files changed, 44 insertions(+)

diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c index 9f48798a713d..714b55f1da0f 100644 --- a/drivers/leds/led-class.c +++ b/drivers/leds/led-class.c @@ -263,6 +263,48 @@ void led_put(struct led_classdev *led_cdev) } EXPORT_SYMBOL_GPL(led_put);

+static void devm_led_release(struct device *dev, void *res) +{ + struct led_classdev **p = res; + + led_put(*p); +} + +/** + * devm_led_get - Resource-managed request of a LED device + * @dev: LED consumer + * @idx: index of the LED to obtain in the consumer + * + * The device node of the device is parse to find the request LED device. + * The LED device returned from this function is automatically released + * on driver detach. + * + * @return a pointer to a LED device or ERR_PTR(errno) on failure. + */ +struct led_classdev *__must_check devm_led_get(struct device *dev, + int index) +{ + struct led_classdev *led; + struct led_classdev **dr; + + led = of_led_get(dev->of_node, index); + if (IS_ERR(led)) + return led; + + dr = devres_alloc(devm_led_release, sizeof(struct led_classdev *), + GFP_KERNEL); + if (!dr) { + led_put(led); + return ERR_PTR(-ENOMEM); + } + + *dr = led; + devres_add(dev, dr); + + return led; +} +EXPORT_SYMBOL_GPL(devm_led_get); + static int match_name(struct device *dev, const void *data) { if (!dev_name(dev)) diff --git a/include/linux/leds.h b/include/linux/leds.h index 0a71c7cdd191..7fcec566d774 100644 --- a/include/linux/leds.h +++ b/include/linux/leds.h @@ -148,6 +148,8 @@ extern void led_classdev_resume(struct led_classdev *led_cdev);

extern struct led_classdev *of_led_get(struct device_node *np, int index); extern void led_put(struct led_classdev *led_cdev); +struct led_classdev *__must_check devm_led_get(struct device *dev, + int index);

/** * led_blink_set - set blinking with software fallback

Add DT binding for led-backlight.

Signed-off-by: Jean-Jacques Hiblot jjhiblot@ti.com --- .../bindings/leds/backlight/led-backlight.txt | 28 +++++++++++++++++++ 1 file changed, 28 insertions(+) create mode 100644 Documentation/devicetree/bindings/leds/backlight/led-backlight.txt

diff --git a/Documentation/devicetree/bindings/leds/backlight/led-backlight.txt b/Documentation/devicetree/bindings/leds/backlight/led-backlight.txt new file mode 100644 index 000000000000..4c7dfbe7f67a --- /dev/null +++ b/Documentation/devicetree/bindings/leds/backlight/led-backlight.txt @@ -0,0 +1,28 @@ +led-backlight bindings + +This binding is used to describe a basic backlight device made of LEDs. +It can also be used to describe a backlight device controlled by the output of +a LED driver. + +Required properties: + - compatible: "led-backlight" + - leds: a list of LEDs + +Optional properties: + - brightness-levels: Array of distinct brightness levels. The levels must be + in the range accepted by the underlying LED devices. + This is used to translate a backlight brightness level + into a LED brightness level. If it is not provided, the + identity mapping is used. + + - default-brightness-level: The default brightness level. + +Example: + + backlight { + compatible = "led-backlight"; + + leds = <&led1>, <&led2>; + brightness-levels = <0 4 8 16 32 64 128 255>; + default-brightness-level = <6>; + };

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 --- drivers/video/backlight/Kconfig | 7 + drivers/video/backlight/Makefile | 1 + drivers/video/backlight/led_bl.c | 268 +++++++++++++++++++++++++++++++ 3 files changed, 276 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..ac5ff78e7859 --- /dev/null +++ b/drivers/video/backlight/led_bl.c @@ -0,0 +1,268 @@ +// 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/gpio/consumer.h> +#include <linux/leds.h> +#include <linux/module.h> +#include <linux/platform_device.h> +#include <linux/slab.h> + +#define BKL_FULL_BRIGHTNESS 255 + +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 int to_led_brightness(struct led_classdev *led, int value) +{ + return (value * led->max_brightness) / BKL_FULL_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++) { + int led_brightness; + struct led_classdev *led = priv->leds[i]; + + led_brightness = to_led_brightness(led, bkl_brightness); + led_set_brightness(led, led_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; + + 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); + } + + 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; + + backlight_device_unregister(bl); + + led_bl_power_off(priv); + + 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");