From 699a8c7c4bd376aee4808e6272188319e900c8af Mon Sep 17 00:00:00 2001
From: Tomi Valkeinen <tomi.valkeinen@ti.com>
Date: Thu, 3 Oct 2019 10:28:09 +0200
Subject: [PATCH] leds: Add of_led_get() and led_put()
Git-commit: 699a8c7c4bd376aee4808e6272188319e900c8af
Patch-mainline: v5.6-rc1
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322

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>
Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/leds/led-class.c |   44 ++++++++++++++++++++++++++++++++++++++++++++
 include/linux/leds.h     |    4 ++++
 2 files changed, 48 insertions(+)

--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -18,6 +18,7 @@
 #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);
+	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)
 {
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -19,6 +19,7 @@
 
 struct device;
 struct led_pattern;
+struct device_node;
 /*
  * LED Core
  */
@@ -141,6 +142,9 @@ extern void devm_led_classdev_unregister
 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