[PATCH v7 0/5] Add a generic driver for LED-based backlight

[PATCH v7 0/5] Add a generic driver for LED-based backlight

[Jean-Jacques Hiblot]

This series aims to add a led-backlight driver, similar to pwm-backlight,
but using a LED class device underneath.

A few years ago (2015), Tomi Valkeinen posted a series implementing a
backlight driver on top of a LED device:
https://patchwork.kernel.org/patch/7293991/
https://patchwork.kernel.org/patch/7294001/
https://patchwork.kernel.org/patch/7293981/

The discussion stopped because Tomi lacked the time to work on it.

changes in v7:
- rebased on top of linux-leds/for-next
- populate the of_node member of the LED device if fwnode is a of_node
  (this is a new patch and the first of the series).
- devm_led_get() works only when the device tree is used. Add a few checks
  for that.  

changes in v6:
- trim the list of included headers
- remove useless definition of BKL_FULL_BRIGHTNESS

changes in v5:
- removed LED brightness scaling
- disable sysfs the interface of the LEDs when used by the backlight device

changes in v4:
- fix dev_err() messages and commit logs following the advices of Pavel
- cosmetic changes (indents, getting rid of  "? 1 : 0" in
  led_match_led_node())

changes in v3:
- dt binding: don't limit the brightness range to 0-255. Use the range of
  the underlying LEDs. as a side-effect, all LEDs must now have the same
  range
- driver: Adapt to dt binding update.
- driver: rework probe() for clarity and remove the remaining goto.

changes in v2:
- handle more than one LED.
- don't make the backlight device a child of the LED controller.
- make brightness-levels and default-brightness-level optional
- removed the option to use a GPIO enable.
- removed the option to use a regulator. It should be handled by the LED
  core
- don't make any change to the LED core (not needed anymore)

Jean-Jacques Hiblot (3):
  leds: populate the device's of_node when possible
  leds: Add managed API to get a LED from a device driver
  dt-bindings: backlight: Add led-backlight binding

Tomi Valkeinen (2):
  leds: Add of_led_get() and led_put()
  backlight: add led-backlight driver

 .../bindings/leds/backlight/led-backlight.txt |  28 ++
 drivers/leds/led-class.c                      | 106 ++++++-
 drivers/video/backlight/Kconfig               |   7 +
 drivers/video/backlight/Makefile              |   1 +
 drivers/video/backlight/led_bl.c              | 260 ++++++++++++++++++
 include/linux/leds.h                          |   6 +
 6 files changed, 407 insertions(+), 1 deletion(-)
 create mode 100644 Documentation/devicetree/bindings/leds/backlight/led-backlight.txt
 create mode 100644 drivers/video/backlight/led_bl.c

-- 
2.17.1

[PATCH v7 1/5] leds: populate the device's of_node when possible

[Jean-Jacques Hiblot]

If initialization data is available and its fwnode is actually a of_node,
store this information in the led device's structure. This will allow the
device to use or provide OF-based API such (devm_xxx).

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
---
 drivers/leds/led-class.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 647b1263c579..c2167b66b61f 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -276,8 +276,11 @@ int led_classdev_register_ext(struct device *parent,
 		mutex_unlock(&led_cdev->led_access);
 		return PTR_ERR(led_cdev->dev);
 	}
-	if (init_data && init_data->fwnode)
+	if (init_data && init_data->fwnode) {
 		led_cdev->dev->fwnode = init_data->fwnode;
+		if (is_of_node(init_data->fwnode))
+			led_cdev->dev->of_node = to_of_node(init_data->fwnode);
+	}
 
 	if (ret)
 		dev_warn(parent, "Led %s renamed to %s due to name collision",
-- 
2.17.1

[PATCH v7 2/5] leds: Add of_led_get() and led_put()

[Jean-Jacques Hiblot]

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>
Acked-by: Pavel Machek <pavel@ucw.cz>
---
 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 c2167b66b61f..2b8f20f94128 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -19,6 +19,7 @@
 #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;
@@ -214,6 +215,55 @@ 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_of_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_of_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 led_classdev_next_name(const char *init_name, char *name,
 				  size_t len)
 {
diff --git a/include/linux/leds.h b/include/linux/leds.h
index b8df71193329..6f7371bc7757 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -20,6 +20,7 @@
 
 struct device;
 struct led_pattern;
+struct device_node;
 /*
  * LED Core
  */
@@ -196,6 +197,9 @@ 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
-- 
2.17.1

[PATCH v7 3/5] leds: Add managed API to get a LED from a device driver

[Jean-Jacques Hiblot]

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 | 51 ++++++++++++++++++++++++++++++++++++++++
 include/linux/leds.h     |  2 ++
 2 files changed, 53 insertions(+)

diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 2b8f20f94128..e11177d77b4c 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -264,6 +264,57 @@ 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.
+ *
+ * NOTE: At the moment, it supports only device-tree based LED lookup
+ *
+ * @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;
+
+	if (!dev)
+		return ERR_PTR(-EINVAL);
+
+	/* Not using device tree? */
+	if (!IS_ENABLED(CONFIG_OF) || !dev->of_node)
+		return ERR_PTR(-ENOTSUPP);
+
+	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 led_classdev_next_name(const char *init_name, char *name,
 				  size_t len)
 {
diff --git a/include/linux/leds.h b/include/linux/leds.h
index 6f7371bc7757..88bf2ceaabe6 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -199,6 +199,8 @@ 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
-- 
2.17.1

[PATCH v7 4/5] dt-bindings: backlight: Add led-backlight binding

[Jean-Jacques Hiblot]

Add DT binding for led-backlight.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
---
 .../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>;
+	};
-- 
2.17.1

[PATCH v7 5/5] backlight: add led-backlight driver

[Jean-Jacques Hiblot]

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

Re: [PATCH v7 1/5] leds: populate the device's of_node when possible

[Jacek Anaszewski]

Hi Jean,

Thank you for rebasing the set

On 9/18/19 4:57 PM, Jean-Jacques Hiblot wrote:
> If initialization data is available and its fwnode is actually a of_node,
> store this information in the led device's structure. This will allow the
> device to use or provide OF-based API such (devm_xxx).
> 
> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
> ---
>  drivers/leds/led-class.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
> index 647b1263c579..c2167b66b61f 100644
> --- a/drivers/leds/led-class.c
> +++ b/drivers/leds/led-class.c
> @@ -276,8 +276,11 @@ int led_classdev_register_ext(struct device *parent,
>  		mutex_unlock(&led_cdev->led_access);
>  		return PTR_ERR(led_cdev->dev);
>  	}
> -	if (init_data && init_data->fwnode)
> +	if (init_data && init_data->fwnode) {
>  		led_cdev->dev->fwnode = init_data->fwnode;
> +		if (is_of_node(init_data->fwnode))
> +			led_cdev->dev->of_node = to_of_node(init_data->fwnode);

It would be step backwards. You can do the conversion in the place of
use i.e. in devm_led_get().

> +	}
>  
>  	if (ret)
>  		dev_warn(parent, "Led %s renamed to %s due to name collision",
> 

-- 
Best regards,
Jacek Anaszewski

Re: [PATCH v7 2/5] leds: Add of_led_get() and led_put()

[Jacek Anaszewski]

Hi Jean,

Thank you for the patch.

I have one nit below.

On 9/18/19 4:57 PM, Jean-Jacques Hiblot wrote:
> 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>
> Acked-by: Pavel Machek <pavel@ucw.cz>
> ---
>  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 c2167b66b61f..2b8f20f94128 100644
> --- a/drivers/leds/led-class.c
> +++ b/drivers/leds/led-class.c
> @@ -19,6 +19,7 @@
>  #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;
> @@ -214,6 +215,55 @@ 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_of_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_of_node);

Now we have class_find_device_by_of_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 led_classdev_next_name(const char *init_name, char *name,
>  				  size_t len)
>  {
> diff --git a/include/linux/leds.h b/include/linux/leds.h
> index b8df71193329..6f7371bc7757 100644
> --- a/include/linux/leds.h
> +++ b/include/linux/leds.h
> @@ -20,6 +20,7 @@
>  
>  struct device;
>  struct led_pattern;
> +struct device_node;
>  /*
>   * LED Core
>   */
> @@ -196,6 +197,9 @@ 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
> 

-- 
Best regards,
Jacek Anaszewski

Re: [PATCH v7 3/5] leds: Add managed API to get a LED from a device driver

[Jacek Anaszewski]

Jean,

On 9/18/19 4:57 PM, Jean-Jacques Hiblot wrote:
> 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 | 51 ++++++++++++++++++++++++++++++++++++++++
>  include/linux/leds.h     |  2 ++
>  2 files changed, 53 insertions(+)
> 
> diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
> index 2b8f20f94128..e11177d77b4c 100644
> --- a/drivers/leds/led-class.c
> +++ b/drivers/leds/led-class.c
> @@ -264,6 +264,57 @@ 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.
> + *
> + * NOTE: At the moment, it supports only device-tree based LED lookup
> + *
> + * @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)

s/devm_led_get/devm_of_led_get/

> +{
> +	struct led_classdev *led;
> +	struct led_classdev **dr;
> +
> +	if (!dev)
> +		return ERR_PTR(-EINVAL);
> +
> +	/* Not using device tree? */
> +	if (!IS_ENABLED(CONFIG_OF) || !dev->of_node)
> +		return ERR_PTR(-ENOTSUPP);
> +
> +	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 led_classdev_next_name(const char *init_name, char *name,
>  				  size_t len)
>  {
> diff --git a/include/linux/leds.h b/include/linux/leds.h
> index 6f7371bc7757..88bf2ceaabe6 100644
> --- a/include/linux/leds.h
> +++ b/include/linux/leds.h
> @@ -199,6 +199,8 @@ 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
> 

-- 
Best regards,
Jacek Anaszewski

Re: [PATCH v7 1/5] leds: populate the device's of_node when possible

[Jean-Jacques Hiblot]

Hi Jacek,

On 24/09/2019 23:03, Jacek Anaszewski wrote:
> Hi Jean,
>
> Thank you for rebasing the set
>
> On 9/18/19 4:57 PM, Jean-Jacques Hiblot wrote:
>> If initialization data is available and its fwnode is actually a of_node,
>> store this information in the led device's structure. This will allow the
>> device to use or provide OF-based API such (devm_xxx).
>>
>> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
>> ---
>>   drivers/leds/led-class.c | 5 ++++-
>>   1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
>> index 647b1263c579..c2167b66b61f 100644
>> --- a/drivers/leds/led-class.c
>> +++ b/drivers/leds/led-class.c
>> @@ -276,8 +276,11 @@ int led_classdev_register_ext(struct device *parent,
>>   		mutex_unlock(&led_cdev->led_access);
>>   		return PTR_ERR(led_cdev->dev);
>>   	}
>> -	if (init_data && init_data->fwnode)
>> +	if (init_data && init_data->fwnode) {
>>   		led_cdev->dev->fwnode = init_data->fwnode;
>> +		if (is_of_node(init_data->fwnode))
>> +			led_cdev->dev->of_node = to_of_node(init_data->fwnode);
> It would be step backwards. You can do the conversion in the place of
> use i.e. in devm_led_get().

Could be done. But it would break another use case I have. I'm also 
working on the regulator support and for this one, of_node needs to be 
populated.

Is there a problem populating of_node if the LED is indeed described in 
the DT ?

JJ

>
>> +	}
>>   
>>   	if (ret)
>>   		dev_warn(parent, "Led %s renamed to %s due to name collision",
>>

Re: [PATCH v7 1/5] leds: populate the device's of_node when possible

[Jacek Anaszewski]

Hi Jean,

On 10/2/19 3:58 PM, Jean-Jacques Hiblot wrote:
> Hi Jacek,
> 
> On 24/09/2019 23:03, Jacek Anaszewski wrote:
>> Hi Jean,
>>
>> Thank you for rebasing the set
>>
>> On 9/18/19 4:57 PM, Jean-Jacques Hiblot wrote:
>>> If initialization data is available and its fwnode is actually a
>>> of_node,
>>> store this information in the led device's structure. This will allow
>>> the
>>> device to use or provide OF-based API such (devm_xxx).
>>>
>>> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
>>> ---
>>>   drivers/leds/led-class.c | 5 ++++-
>>>   1 file changed, 4 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
>>> index 647b1263c579..c2167b66b61f 100644
>>> --- a/drivers/leds/led-class.c
>>> +++ b/drivers/leds/led-class.c
>>> @@ -276,8 +276,11 @@ int led_classdev_register_ext(struct device
>>> *parent,
>>>           mutex_unlock(&led_cdev->led_access);
>>>           return PTR_ERR(led_cdev->dev);
>>>       }
>>> -    if (init_data && init_data->fwnode)
>>> +    if (init_data && init_data->fwnode) {
>>>           led_cdev->dev->fwnode = init_data->fwnode;
>>> +        if (is_of_node(init_data->fwnode))
>>> +            led_cdev->dev->of_node = to_of_node(init_data->fwnode);
>> It would be step backwards. You can do the conversion in the place of
>> use i.e. in devm_led_get().
> 
> Could be done. But it would break another use case I have. I'm also
> working on the regulator support and for this one, of_node needs to be
> populated.

I thought that regulator core can do the conversion to of_node itself,
but this seems not to be the case.

> Is there a problem populating of_node if the LED is indeed described in
> the DT ?

No, if it is not possible to do it otherwise.

-- 
Best regards,
Jacek Anaszewski

Re: [PATCH v7 4/5] dt-bindings: backlight: Add led-backlight binding

[Lee Jones]

On Wed, 18 Sep 2019, Jean-Jacques Hiblot wrote:

> Add DT binding for led-backlight.
> 
> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
> ---
>  .../bindings/leds/backlight/led-backlight.txt | 28 +++++++++++++++++++
>  1 file changed, 28 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/leds/backlight/led-backlight.txt

Applied, thanks.

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog

Re: [PATCH v7 5/5] backlight: add led-backlight driver

[Lee Jones]

On Wed, 18 Sep 2019, 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

Applied, thanks.

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog

Re: [PATCH v7 5/5] backlight: add led-backlight driver

[Jean-Jacques Hiblot]

Hi Lee,

On 04/10/2019 16:39, Lee Jones wrote:
> On Wed, 18 Sep 2019, 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
> Applied, thanks.

It will break the build because it relies on functions not yet in the 
LED core (devm_led_get() for v7 or devm_of_led_get() for v8)

JJ

>

Re: [PATCH v7 5/5] backlight: add led-backlight driver

[Lee Jones]

On Fri, 04 Oct 2019, Jean-Jacques Hiblot wrote:

> Hi Lee,
> 
> On 04/10/2019 16:39, Lee Jones wrote:
> > On Wed, 18 Sep 2019, 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
> > Applied, thanks.
> 
> It will break the build because it relies on functions not yet in the LED
> core (devm_led_get() for v7 or devm_of_led_get() for v8)

You're right, un-applied, thanks.

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog