Re: [PATCH 1/3] leds: Add of_led_get() and led_put()

[Jacek Anaszewski <j.anaszewski@samsung.com>]

Hi Tomi,

Thanks for the patch. Generally, I'd prefer to add files
drivers/leds/of.c and include/linux/of_leds.h and put related functions
there. Those functions' names should begin with "of_". Please provide
also no-op versions of the functions to address configurations when
CONFIG_OF isn't enabled. I have also few comments below.

On 08/25/2015 01:34 PM, Tomi Valkeinen wrote:
> 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>
> ---
>   drivers/leds/led-class.c | 75 ++++++++++++++++++++++++++++++++++++++++++++++++
>   include/linux/leds.h     |  4 +++
>   2 files changed, 79 insertions(+)
>
> diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
> index beabfbc6f7cd..0cb4fd7d71d6 100644
> --- a/drivers/leds/led-class.c
> +++ b/drivers/leds/led-class.c
> @@ -20,6 +20,7 @@
>   #include <linux/slab.h>
>   #include <linux/spinlock.h>
>   #include <linux/timer.h>
> +#include <linux/of.h>
>   #include "leds.h"
>
>   static struct class *leds_class;
> @@ -216,6 +217,80 @@ static int led_resume(struct device *dev)
>
>   static SIMPLE_DEV_PM_OPS(leds_class_dev_pm_ops, led_suspend, led_resume);
>
> +/* find OF node for the given led_cdev */
> +static struct device_node *find_led_of_node(struct led_classdev *led_cdev)
> +{
> +	struct device *led_dev = led_cdev->dev;
> +	struct device_node *child;
> +
> +	for_each_child_of_node(led_dev->parent->of_node, child) {
> +		if (of_property_match_string(child, "label", led_cdev->name) == 0)
> +			return child;
> +	}
> +
> +	return NULL;
> +}
> +
> +static int led_match_led_node(struct device *led_dev, const void *data)
> +{
> +	struct led_classdev *led_cdev = dev_get_drvdata(led_dev);
> +	const struct device_node *target_node = data;
> +	struct device_node *led_node;
> +
> +	led_node = find_led_of_node(led_cdev);
> +	if (!led_node)
> +		return 0;
> +
> +	of_node_put(led_node);
> +
> +	return led_node == target_node ? 1 : 0;
> +}
> +
> +/**
> + * of_led_get() - request a LED device via the LED framework
> + * @np: device node to get the LED device from
> + *
> + * 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)
> +{
> +	struct device *led_dev;
> +	struct led_classdev *led_cdev;
> +	struct device_node *led_node;
> +
> +	led_node = of_parse_phandle(np, "leds", 0);
> +	if (!led_node)
> +		return ERR_PTR(-ENODEV);
> +
> +	led_dev = class_find_device(leds_class, NULL, led_node,
> +		led_match_led_node);

Single of_node_put(led_node) here will do.

> +	if (!led_dev) {
> +		of_node_put(led_node);
> +		return ERR_PTR(-EPROBE_DEFER);
> +	}
> +
> +	of_node_put(led_node);

> +	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);

Please move it to include/linux/leds.h, make static inline and provide
also no-op version for the case when CONFIG_LEDS_CLASS isn't enabled.

>   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 b122eeafb5dc..efc9b28af564 100644
> --- a/include/linux/leds.h
> +++ b/include/linux/leds.h
> @@ -21,6 +21,7 @@
>   #include <linux/workqueue.h>
>
>   struct device;
> +struct device_node;
>   /*
>    * LED Core
>    */
> @@ -113,6 +114,9 @@ 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);

We need also no-op version for (!CONFIG_OF || !CONFIG_LEDS_CLASS).

> +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