[PATCH v10 2/6] leds: Add of_led_get() and led_put()

From: Jean-Jacques Hiblot
Date: Wed Oct 09 2019 - 04:51:55 EST


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 | 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