linux-kernel - [PATCH/RFC v5 3/4] leds: add API for setting torch brightness

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Message-id: <1408542118-32723-4-git-send-email-j.anaszewski@samsung.com>
Date:	Wed, 20 Aug 2014 15:41:57 +0200
From:	Jacek Anaszewski <j.anaszewski@...sung.com>
To:	linux-leds@...r.kernel.org, devicetree@...r.kernel.org,
	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:	kyungmin.park@...sung.com, b.zolnierkie@...sung.com,
	Jacek Anaszewski <j.anaszewski@...sung.com>,
	Bryan Wu <cooloney@...il.com>,
	Richard Purdie <rpurdie@...ys.net>
Subject: [PATCH/RFC v5 3/4] leds: add API for setting torch brightness

This patch prepares ground for addition of LED Flash Class extension to
the LED subsystem. Since turning the torch on must have guaranteed
immediate effect the brightness_set op can't be used for it. Drivers must
schedule a work queue task in this op to be compatible with led-triggers,
which call brightess_set from timer irqs. In order to address this
limitation a torch_brightness_set op and led_set_torch_brightness API
is introduced. Setting brightness sysfs attribute will result in calling
brightness_set op for LED Class devices and torch_brightness_set op for
LED Flash Class devices, whereas triggers will still call brightness
op in both cases.

Signed-off-by: Jacek Anaszewski <j.anaszewski@...sung.com>
Acked-by: Kyungmin Park <kyungmin.park@...sung.com>
Cc: Bryan Wu <cooloney@...il.com>
Cc: Richard Purdie <rpurdie@...ys.net>
---
 drivers/leds/led-class.c |    9 +++++++--
 drivers/leds/led-core.c  |   14 ++++++++++++++
 include/linux/leds.h     |   21 +++++++++++++++++++++
 3 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 0bc0ba9..f640da9 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -56,9 +56,14 @@ static ssize_t brightness_store(struct device *dev,
 
 	if (state == LED_OFF)
 		led_trigger_remove(led_cdev);
-	__led_set_brightness(led_cdev, state);
 
-	ret = size;
+	if (led_cdev->flags & LED_DEV_CAP_TORCH)
+		ret = led_set_torch_brightness(led_cdev, state);
+	else
+		__led_set_brightness(led_cdev, state);
+
+	if (!ret)
+		ret = size;
 unlock:
 #ifdef CONFIG_V4L2_FLASH_LED_CLASS
 	mutex_unlock(&led_cdev->led_lock);
diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
index 4649ea5..093265f 100644
--- a/drivers/leds/led-core.c
+++ b/drivers/leds/led-core.c
@@ -144,6 +144,20 @@ int led_update_brightness(struct led_classdev *led_cdev)
 }
 EXPORT_SYMBOL(led_update_brightness);
 
+int led_set_torch_brightness(struct led_classdev *led_cdev,
+				enum led_brightness brightness)
+{
+	int ret = 0;
+
+	led_cdev->brightness = min(brightness, led_cdev->max_brightness);
+
+	if (!(led_cdev->flags & LED_SUSPENDED))
+		ret = led_cdev->torch_brightness_set(led_cdev,
+						     led_cdev->brightness);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(led_set_torch_brightness);
+
 /* Caller must ensure led_cdev->led_lock held */
 void led_sysfs_lock(struct led_classdev *led_cdev)
 {
diff --git a/include/linux/leds.h b/include/linux/leds.h
index ef343f1..df0715c 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -43,11 +43,21 @@ struct led_classdev {
 #define LED_BLINK_ONESHOT_STOP	(1 << 18)
 #define LED_BLINK_INVERT	(1 << 19)
 #define LED_SYSFS_LOCK		(1 << 20)
+#define LED_DEV_CAP_TORCH	(1 << 21)
 
 	/* Set LED brightness level */
 	/* Must not sleep, use a workqueue if needed */
 	void		(*brightness_set)(struct led_classdev *led_cdev,
 					  enum led_brightness brightness);
+	/*
+	 * Set LED brightness immediately - it is required for flash led
+	 * devices as they require setting torch brightness to have immediate
+	 * effect. brightness_set op cannot be used for this purpose because
+	 * the led drivers schedule a work queue task in it to allow for
+	 * being called from led-triggers, i.e. from the timer irq context.
+	 */
+	int		(*torch_brightness_set)(struct led_classdev *led_cdev,
+					enum led_brightness brightness);
 	/* Get LED brightness level */
 	enum led_brightness (*brightness_get)(struct led_classdev *led_cdev);
 
@@ -156,6 +166,17 @@ extern void led_set_brightness(struct led_classdev *led_cdev,
 extern int led_update_brightness(struct led_classdev *led_cdev);
 
 /**
+ * led_set_torch_brightness - set torch LED brightness
+ * @led_cdev: the LED to set
+ * @brightness: the brightness to set it to
+ *
+ * Returns: 0 on success or negative error value on failure
+ *
+ * Set a torch LED's brightness.
+ */
+extern int led_set_torch_brightness(struct led_classdev *led_cdev,
+					enum led_brightness brightness);
+/**
  * led_sysfs_lock - lock LED sysfs interface
  * @led_cdev: the LED to set
  *
-- 
1.7.9.5

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