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

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Hi Sebastian,

On 03/10/2019 12:42, Sebastian Reichel wrote:
Hi,

On Thu, Oct 03, 2019 at 10:28:09AM +0200, Jean-Jacques Hiblot wrote:
From: Tomi Valkeinen <tomi.valkeinen@xxxxxx>

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@xxxxxx>
Signed-off-by: Jean-Jacques Hiblot <jjhiblot@xxxxxx>
Acked-by: Pavel Machek <pavel@xxxxxx>
---
  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.

Thanks for the reviews.

The first patch could be dropped  indeed, but it would break something else I'm working on: getting regulator support in the LED core.

This has been discussed during the v7 iteration of this series.

JJ



-- 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

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