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 v9:
- let to_of_node() check if the fwnode is actually a of_node
- add some checks in of_led_get()
- let dev_of_node() do the check about OF availabilty
- refactor led_bl_probe() to register a cleanup function with
devm_add_action_or_reset(). This simplifies the error handling (which
was not 100% done in v7) and allows to get rid of led_bl_remove()
changes in v8:
- use class_find_device_by_of_node() instead of class_find_device()
- renamed devm_led_get() as devm_of_led_get()
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
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 | 103 ++++++-
drivers/video/backlight/Kconfig | 7 +
drivers/video/backlight/Makefile | 1 +
drivers/video/backlight/led_bl.c | 258 ++++++++++++++++++
include/linux/leds.h | 6 +
6 files changed, 402 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
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 <[email protected]>
Acked-by: Pavel Machek <[email protected]>
---
drivers/leds/led-class.c | 49 ++++++++++++++++++++++++++++++++++++++++
include/linux/leds.h | 2 ++
2 files changed, 51 insertions(+)
diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 1d1f1d546dc7..639224392ffa 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -264,6 +264,55 @@ 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_of_led_get - Resource-managed request of a LED device
+ * @dev: LED consumer
+ * @index: 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_of_led_get(struct device *dev,
+ int index)
+{
+ struct led_classdev *led;
+ struct led_classdev **dr;
+
+ if (!dev)
+ return ERR_PTR(-EINVAL);
+
+ /* Consummer not using device tree? */
+ if (!dev_of_node(dev))
+ return ERR_PTR(-ENOTSUPP);
+
+ led = of_led_get(dev_of_node(dev), 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_of_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..9b94cf752012 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_of_led_get(struct device *dev,
+ int index);
/**
* led_blink_set - set blinking with software fallback
--
2.17.1
From: Tomi Valkeinen <[email protected]>
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 <[email protected]>
Signed-off-by: Jean-Jacques Hiblot <[email protected]>
Acked-by: Pavel Machek <[email protected]>
---
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 bfa1b1033274..1d1f1d546dc7 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);
+/**
+ * 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;
+
+ /* Not using device tree? */
+ if (!IS_ENABLED(CONFIG_OF))
+ return ERR_PTR(-ENOTSUPP);
+ if (!np)
+ return ERR_PTR(-EINVAL);
+
+ led_node = of_parse_phandle(np, "leds", index);
+ if (!led_node)
+ return ERR_PTR(-ENOENT);
+
+ led_dev = class_find_device_by_of_node(leds_class, 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 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
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 <[email protected]>
---
drivers/leds/led-class.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 647b1263c579..bfa1b1033274 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -276,8 +276,10 @@ 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;
+ 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
Hi!
> 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 <[email protected]>
> Acked-by: Pavel Machek <[email protected]>
> ---
> drivers/leds/led-class.c | 49 ++++++++++++++++++++++++++++++++++++++++
> include/linux/leds.h | 2 ++
> 2 files changed, 51 insertions(+)
>
> diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
> index 1d1f1d546dc7..639224392ffa 100644
> --- a/drivers/leds/led-class.c
> +++ b/drivers/leds/led-class.c
> @@ -264,6 +264,55 @@ 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_of_led_get - Resource-managed request of a LED device
> + * @dev: LED consumer
> + * @index: 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_of_led_get(struct device *dev,
> + int index)
> +{
> + struct led_classdev *led;
> + struct led_classdev **dr;
> +
> + if (!dev)
> + return ERR_PTR(-EINVAL);
> +
> + /* Consummer not using device tree? */
Typo "consumer". I may fix it before applying the patch.
Best regards,
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html