linux-kernel - [PATCH 1/3] video / backlight: add two APIs for drivers to use

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Message-Id: <1419997818-19528-2-git-send-email-aaron.lu@intel.com>
Date:	Wed, 31 Dec 2014 11:50:16 +0800
From:	Aaron Lu <aaron.lu@...el.com>
To:	Jingoo Han <jg1.han@...sung.com>, Lee Jones <lee.jones@...aro.org>,
	Zhang Rui <rui.zhang@...el.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org
Subject: [PATCH 1/3] video / backlight: add two APIs for drivers to use

It is useful to get the backlight device's pointer and use it to set
backlight in some cases(the following patch will make use of it) so add
the two APIs and export them.

Signed-off-by: Aaron Lu <aaron.lu@...el.com>
---
 drivers/video/backlight/backlight.c | 44 ++++++++++++++++++++++++-------------
 include/linux/backlight.h           |  2 ++
 2 files changed, 31 insertions(+), 15 deletions(-)

diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
index bddc8b17a4d8..bea749329236 100644
--- a/drivers/video/backlight/backlight.c
+++ b/drivers/video/backlight/backlight.c
@@ -164,28 +164,19 @@ static ssize_t brightness_show(struct device *dev,
 	return sprintf(buf, "%d\n", bd->props.brightness);
 }
 
-static ssize_t brightness_store(struct device *dev,
-		struct device_attribute *attr, const char *buf, size_t count)
+int backlight_device_set_brightness(struct backlight_device *bd, int brightness)
 {
-	int rc;
-	struct backlight_device *bd = to_backlight_device(dev);
-	unsigned long brightness;
-
-	rc = kstrtoul(buf, 0, &brightness);
-	if (rc)
-		return rc;
-
-	rc = -ENXIO;
+	int rc = -ENXIO;
 
 	mutex_lock(&bd->ops_lock);
 	if (bd->ops) {
 		if (brightness > bd->props.max_brightness)
 			rc = -EINVAL;
 		else {
-			pr_debug("set brightness to %lu\n", brightness);
+			pr_debug("set brightness to %u\n", brightness);
 			bd->props.brightness = brightness;
 			backlight_update_status(bd);
-			rc = count;
+			rc = 0;
 		}
 	}
 	mutex_unlock(&bd->ops_lock);
@@ -194,6 +185,23 @@ static ssize_t brightness_store(struct device *dev,
 
 	return rc;
 }
+EXPORT_SYMBOL(backlight_device_set_brightness);
+
+static ssize_t brightness_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t count)
+{
+	int rc;
+	struct backlight_device *bd = to_backlight_device(dev);
+	unsigned long brightness;
+
+	rc = kstrtoul(buf, 0, &brightness);
+	if (rc)
+		return rc;
+
+	rc = backlight_device_set_brightness(bd, brightness);
+
+	return rc ? rc : count;
+}
 static DEVICE_ATTR_RW(brightness);
 
 static ssize_t type_show(struct device *dev, struct device_attribute *attr,
@@ -380,7 +388,7 @@ struct backlight_device *backlight_device_register(const char *name,
 }
 EXPORT_SYMBOL(backlight_device_register);
 
-bool backlight_device_registered(enum backlight_type type)
+struct backlight_device *backlight_device_get_by_type(enum backlight_type type)
 {
 	bool found = false;
 	struct backlight_device *bd;
@@ -394,7 +402,13 @@ bool backlight_device_registered(enum backlight_type type)
 	}
 	mutex_unlock(&backlight_dev_list_mutex);
 
-	return found;
+	return found ? bd : NULL;
+}
+EXPORT_SYMBOL(backlight_device_get_by_type);
+
+bool backlight_device_registered(enum backlight_type type)
+{
+	return backlight_device_get_by_type(type) ? true : false;
 }
 EXPORT_SYMBOL(backlight_device_registered);
 
diff --git a/include/linux/backlight.h b/include/linux/backlight.h
index adb14a8616df..c59a020df3f8 100644
--- a/include/linux/backlight.h
+++ b/include/linux/backlight.h
@@ -140,6 +140,8 @@ extern void backlight_force_update(struct backlight_device *bd,
 extern bool backlight_device_registered(enum backlight_type type);
 extern int backlight_register_notifier(struct notifier_block *nb);
 extern int backlight_unregister_notifier(struct notifier_block *nb);
+extern struct backlight_device *backlight_device_get_by_type(enum backlight_type type);
+extern int backlight_device_set_brightness(struct backlight_device *bd, int brightness);
 
 #define to_backlight_device(obj) container_of(obj, struct backlight_device, dev)
 
-- 
2.1.0

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