linux-kernel - Re: [PATCH v8 2/5] leds: Add of_led_get() and led_put()

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Message-ID: <20191003104228.c5nho6eimwzqwxpt@earth.universe>
Date:   Thu, 3 Oct 2019 12:42:28 +0200
From:   Sebastian Reichel <sebastian.reichel@...labora.com>
To:     Jean-Jacques Hiblot <jjhiblot@...com>
Cc:     jacek.anaszewski@...il.com, pavel@....cz, robh+dt@...nel.org,
        mark.rutland@....com, lee.jones@...aro.org,
        daniel.thompson@...aro.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, tomi.valkeinen@...com,
        dmurphy@...com, linux-leds@...r.kernel.org
Subject: Re: [PATCH v8 2/5] leds: Add of_led_get() and led_put()

Hi,

On Thu, Oct 03, 2019 at 10:28:09AM +0200, Jean-Jacques Hiblot wrote:
> From: Tomi Valkeinen <tomi.valkeinen@...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@...com>
> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@...com>
> Acked-by: Pavel Machek <pavel@....cz>
> ---
>  drivers/leds/led-class.c | 44 ++++++++++++++++++++++++++++++++++++++++
>  include/linux/leds.h     |  4 ++++
>  2 files changed, 48 insertions(+)
> 
> diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
> index c2167b66b61f..455545f5d663 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 +215,49 @@ 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;
> +
> +	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);

If you convert led_node into a fwnode, you can use
class_find_device_by_fwnode() instead. That way the
first patch can just be dropped.

-- Sebastian

> +	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
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel@...ts.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

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