[PATCH/RFC v5 0/4] LED / flash API integration - LED Flash Class

[PATCH/RFC v5 0/4] LED / flash API integration - LED Flash Class

[Jacek Anaszewski]

This patch set is the follow-up of the LED / flash API integration
series [1]. For clarity reasons the patchset has been split into
five subsets:

- LED Flash Class
- Flash Manager
- V4L2 Flash
- LED Flash Class drivers
- Documentation

The series is based on linux-next-20140820.

Thanks,
Jacek Anaszewski

[1] https://lkml.org/lkml/2014/7/11/914

Jacek Anaszewski (4):
  leds: Improve and export led_update_brightness
  leds: implement sysfs interface locking mechanism
  leds: add API for setting torch brightness
  leds: Add LED Flash Class wrapper to LED subsystem

 drivers/leds/Kconfig            |   11 +
 drivers/leds/Makefile           |    1 +
 drivers/leds/led-class-flash.c  |  645 +++++++++++++++++++++++++++++++++++++++
 drivers/leds/led-class.c        |   40 ++-
 drivers/leds/led-core.c         |   48 +++
 drivers/leds/led-triggers.c     |   20 +-
 include/linux/led-class-flash.h |  273 +++++++++++++++++
 include/linux/leds.h            |   66 ++++
 8 files changed, 1091 insertions(+), 13 deletions(-)
 create mode 100644 drivers/leds/led-class-flash.c
 create mode 100644 include/linux/led-class-flash.h

-- 
1.7.9.5

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[PATCH/RFC v5 0/4] LED / flash API integration - LED Flash Class

[Jacek Anaszewski]

This patch set is the follow-up of the LED / flash API integration
series [1]. For clarity reasons the patchset has been split into
five subsets:

- LED Flash Class
- Flash Manager
- V4L2 Flash
- LED Flash Class drivers
- Documentation

The series is based on linux-next-20140820.

Thanks,
Jacek Anaszewski

[1] https://lkml.org/lkml/2014/7/11/914

Jacek Anaszewski (4):
  leds: Improve and export led_update_brightness
  leds: implement sysfs interface locking mechanism
  leds: add API for setting torch brightness
  leds: Add LED Flash Class wrapper to LED subsystem

 drivers/leds/Kconfig            |   11 +
 drivers/leds/Makefile           |    1 +
 drivers/leds/led-class-flash.c  |  645 +++++++++++++++++++++++++++++++++++++++
 drivers/leds/led-class.c        |   40 ++-
 drivers/leds/led-core.c         |   48 +++
 drivers/leds/led-triggers.c     |   20 +-
 include/linux/led-class-flash.h |  273 +++++++++++++++++
 include/linux/leds.h            |   66 ++++
 8 files changed, 1091 insertions(+), 13 deletions(-)
 create mode 100644 drivers/leds/led-class-flash.c
 create mode 100644 include/linux/led-class-flash.h

-- 
1.7.9.5

[PATCH/RFC v5 1/4] leds: Improve and export led_update_brightness

[Jacek Anaszewski]

led_update_brightness helper function used to be exploited only locally
in the led-class.c module, where its result was being passed to the
brightness_show sysfs callback. With the introduction of v4l2-flash
subdevice the same functionality becomes required for reading current
brightness from a LED device. This patch adds checking of return value
of the brightness_get callback and moves the led_update_brightness()
function to the LED subsystem public API.

Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Bryan Wu <cooloney@gmail.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
---
 drivers/leds/led-class.c |    6 ------
 drivers/leds/led-core.c  |   16 ++++++++++++++++
 include/linux/leds.h     |   10 ++++++++++
 3 files changed, 26 insertions(+), 6 deletions(-)

diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index f4e5bb4..6f82a76 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -23,12 +23,6 @@
 
 static struct class *leds_class;
 
-static void led_update_brightness(struct led_classdev *led_cdev)
-{
-	if (led_cdev->brightness_get)
-		led_cdev->brightness = led_cdev->brightness_get(led_cdev);
-}
-
 static ssize_t brightness_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
index 8380eb7..466ce5a 100644
--- a/drivers/leds/led-core.c
+++ b/drivers/leds/led-core.c
@@ -127,3 +127,19 @@ void led_set_brightness(struct led_classdev *led_cdev,
 	__led_set_brightness(led_cdev, brightness);
 }
 EXPORT_SYMBOL(led_set_brightness);
+
+int led_update_brightness(struct led_classdev *led_cdev)
+{
+	int ret = 0;
+
+	if (led_cdev->brightness_get) {
+		ret = led_cdev->brightness_get(led_cdev);
+		if (ret >= 0) {
+			led_cdev->brightness = ret;
+			return 0;
+		}
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL(led_update_brightness);
diff --git a/include/linux/leds.h b/include/linux/leds.h
index bc221d11..cc85b16 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -139,6 +139,16 @@ extern void led_blink_set_oneshot(struct led_classdev *led_cdev,
  */
 extern void led_set_brightness(struct led_classdev *led_cdev,
 			       enum led_brightness brightness);
+/**
+ * led_update_brightness - update LED brightness
+ * @led_cdev: the LED to query
+ *
+ * Get an LED's current brightness and update led_cdev->brightness
+ * member with the obtained value.
+ *
+ * Returns: 0 on success or negative error value on failure
+ */
+extern int led_update_brightness(struct led_classdev *led_cdev);
 
 /*
  * LED Triggers
-- 
1.7.9.5

[PATCH/RFC v5 2/4] leds: implement sysfs interface locking mechanism

[Jacek Anaszewski]

Add a mechanism for locking LED subsystem sysfs interface.
This patch prepares ground for addition of LED Flash Class
extension, whose API will be integrated with V4L2 Flash API.
Such a fusion enforces introducing a locking scheme, which
will secure consistent access to the LED Flash Class device.

The mechanism being introduced allows for disabling LED
subsystem sysfs interface by calling led_sysfs_lock function
and enabling it by calling led_sysfs_unlock. The functions
alter the LED_SYSFS_LOCK flag state and must be called
under mutex lock. The state of the lock is checked with use
of led_sysfs_is_locked function. Such a design allows for
providing immediate feedback to the user space on whether
the LED Flash Class device is available or is under V4L2 Flash
sub-device control.

Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Bryan Wu <cooloney@gmail.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
---
 drivers/leds/led-class.c    |   23 ++++++++++++++++++++---
 drivers/leds/led-core.c     |   18 ++++++++++++++++++
 drivers/leds/led-triggers.c |   15 ++++++++++++---
 include/linux/leds.h        |   32 ++++++++++++++++++++++++++++++++
 4 files changed, 82 insertions(+), 6 deletions(-)

diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 6f82a76..0bc0ba9 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -39,17 +39,31 @@ static ssize_t brightness_store(struct device *dev,
 {
 	struct led_classdev *led_cdev = dev_get_drvdata(dev);
 	unsigned long state;
-	ssize_t ret = -EINVAL;
+	ssize_t ret;
+
+#ifdef CONFIG_V4L2_FLASH_LED_CLASS
+	mutex_lock(&led_cdev->led_lock);
+
+	if (led_sysfs_is_locked(led_cdev)) {
+		ret = -EBUSY;
+		goto unlock;
+	}
+#endif
 
 	ret = kstrtoul(buf, 10, &state);
 	if (ret)
-		return ret;
+		goto unlock;
 
 	if (state == LED_OFF)
 		led_trigger_remove(led_cdev);
 	__led_set_brightness(led_cdev, state);
 
-	return size;
+	ret = size;
+unlock:
+#ifdef CONFIG_V4L2_FLASH_LED_CLASS
+	mutex_unlock(&led_cdev->led_lock);
+#endif
+	return ret;
 }
 static DEVICE_ATTR_RW(brightness);
 
@@ -215,6 +229,7 @@ int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
 #ifdef CONFIG_LEDS_TRIGGERS
 	init_rwsem(&led_cdev->trigger_lock);
 #endif
+	mutex_init(&led_cdev->led_lock);
 	/* add to the list of leds */
 	down_write(&leds_list_lock);
 	list_add_tail(&led_cdev->node, &leds_list);
@@ -266,6 +281,8 @@ void led_classdev_unregister(struct led_classdev *led_cdev)
 	down_write(&leds_list_lock);
 	list_del(&led_cdev->node);
 	up_write(&leds_list_lock);
+
+	mutex_destroy(&led_cdev->led_lock);
 }
 EXPORT_SYMBOL_GPL(led_classdev_unregister);
 
diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
index 466ce5a..4649ea5 100644
--- a/drivers/leds/led-core.c
+++ b/drivers/leds/led-core.c
@@ -143,3 +143,21 @@ int led_update_brightness(struct led_classdev *led_cdev)
 	return ret;
 }
 EXPORT_SYMBOL(led_update_brightness);
+
+/* Caller must ensure led_cdev->led_lock held */
+void led_sysfs_lock(struct led_classdev *led_cdev)
+{
+	lockdep_assert_held(&led_cdev->led_lock);
+
+	led_cdev->flags |= LED_SYSFS_LOCK;
+}
+EXPORT_SYMBOL_GPL(led_sysfs_lock);
+
+/* Caller must ensure led_cdev->led_lock held */
+void led_sysfs_unlock(struct led_classdev *led_cdev)
+{
+	lockdep_assert_held(&led_cdev->led_lock);
+
+	led_cdev->flags &= ~LED_SYSFS_LOCK;
+}
+EXPORT_SYMBOL_GPL(led_sysfs_unlock);
diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c
index c3734f1..d391a5d 100644
--- a/drivers/leds/led-triggers.c
+++ b/drivers/leds/led-triggers.c
@@ -37,6 +37,11 @@ ssize_t led_trigger_store(struct device *dev, struct device_attribute *attr,
 	char trigger_name[TRIG_NAME_MAX];
 	struct led_trigger *trig;
 	size_t len;
+	int ret = count;
+
+#ifdef CONFIG_V4L2_FLASH_LED_CLASS
+	mutex_lock(&led_cdev->led_lock);
+#endif
 
 	trigger_name[sizeof(trigger_name) - 1] = '\0';
 	strncpy(trigger_name, buf, sizeof(trigger_name) - 1);
@@ -47,7 +52,7 @@ ssize_t led_trigger_store(struct device *dev, struct device_attribute *attr,
 
 	if (!strcmp(trigger_name, "none")) {
 		led_trigger_remove(led_cdev);
-		return count;
+		goto exit_unlock;
 	}
 
 	down_read(&triggers_list_lock);
@@ -58,12 +63,16 @@ ssize_t led_trigger_store(struct device *dev, struct device_attribute *attr,
 			up_write(&led_cdev->trigger_lock);
 
 			up_read(&triggers_list_lock);
-			return count;
+			goto exit_unlock;
 		}
 	}
 	up_read(&triggers_list_lock);
 
-	return -EINVAL;
+exit_unlock:
+#ifdef CONFIG_V4L2_FLASH_LED_CLASS
+	mutex_unlock(&led_cdev->led_lock);
+#endif
+	return ret;
 }
 EXPORT_SYMBOL_GPL(led_trigger_store);
 
diff --git a/include/linux/leds.h b/include/linux/leds.h
index cc85b16..ef343f1 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -13,6 +13,7 @@
 #define __LINUX_LEDS_H_INCLUDED
 
 #include <linux/list.h>
+#include <linux/mutex.h>
 #include <linux/rwsem.h>
 #include <linux/spinlock.h>
 #include <linux/workqueue.h>
@@ -41,6 +42,7 @@ struct led_classdev {
 #define LED_BLINK_ONESHOT	(1 << 17)
 #define LED_BLINK_ONESHOT_STOP	(1 << 18)
 #define LED_BLINK_INVERT	(1 << 19)
+#define LED_SYSFS_LOCK		(1 << 20)
 
 	/* Set LED brightness level */
 	/* Must not sleep, use a workqueue if needed */
@@ -84,6 +86,9 @@ struct led_classdev {
 	/* true if activated - deactivate routine uses it to do cleanup */
 	bool			activated;
 #endif
+
+	/* Ensures consistent access to the LED Flash Class device */
+	struct mutex		led_lock;
 };
 
 extern int led_classdev_register(struct device *parent,
@@ -150,6 +155,33 @@ extern void led_set_brightness(struct led_classdev *led_cdev,
  */
 extern int led_update_brightness(struct led_classdev *led_cdev);
 
+/**
+ * led_sysfs_lock - lock LED sysfs interface
+ * @led_cdev: the LED to set
+ *
+ * Lock the LED's sysfs interface
+ */
+extern void led_sysfs_lock(struct led_classdev *led_cdev);
+
+/**
+ * led_sysfs_unlock - unlock LED sysfs interface
+ * @led_cdev: the LED to set
+ *
+ * Unlock the LED's sysfs interface
+ */
+extern void led_sysfs_unlock(struct led_classdev *led_cdev);
+
+/**
+ * led_sysfs_is_locked
+ * @led_cdev: the LED to query
+ *
+ * Returns: true if the sysfs interface of the led is locked
+ */
+static inline bool led_sysfs_is_locked(struct led_classdev *led_cdev)
+{
+	return led_cdev->flags & LED_SYSFS_LOCK;
+}
+
 /*
  * LED Triggers
  */
-- 
1.7.9.5

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

[Jacek Anaszewski]

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@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Bryan Wu <cooloney@gmail.com>
Cc: Richard Purdie <rpurdie@rpsys.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

[PATCH/RFC v5 4/4] leds: Add LED Flash Class wrapper to LED subsystem

[Jacek Anaszewski]

Some LED devices support two operation modes - torch and flash.
This patch provides support for flash LED devices in the LED subsystem
by introducing new sysfs attributes and kernel internal interface.
The attributes being introduced are: flash_brightness, flash_strobe,
flash_timeout, max_flash_timeout, max_flash_brightness, flash_fault,
external_strobe, indicator_brightness, max_indicator_brightness.
All the flash related features are placed in a separate module.

The modifications aim to be compatible with V4L2 framework requirements
related to the flash devices management. The design assumes that V4L2
sub-device can take of the LED class device control and communicate
with it through the kernel internal interface. When V4L2 Flash sub-device
file is opened, the LED class device sysfs interface is made
unavailable.

Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Bryan Wu <cooloney@gmail.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
---
 drivers/leds/Kconfig            |   11 +
 drivers/leds/Makefile           |    1 +
 drivers/leds/led-class-flash.c  |  645 +++++++++++++++++++++++++++++++++++++++
 drivers/leds/led-class.c        |    4 +
 drivers/leds/led-triggers.c     |    5 +
 include/linux/led-class-flash.h |  273 +++++++++++++++++
 include/linux/leds.h            |    3 +
 7 files changed, 942 insertions(+)
 create mode 100644 drivers/leds/led-class-flash.c
 create mode 100644 include/linux/led-class-flash.h

diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index f6e32ba..a22c211 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -19,6 +19,17 @@ config LEDS_CLASS
 	  This option enables the led sysfs class in /sys/class/leds.  You'll
 	  need this to do anything useful with LEDs.  If unsure, say N.
 
+config LEDS_CLASS_FLASH
+	tristate "LED Flash Class Support"
+	depends on LEDS_CLASS
+	depends on OF
+	help
+	  This option enables the flash led sysfs class in /sys/class/leds.
+	  It wrapps LED Class and adds flash LEDs specific sysfs attributes
+	  and kernel internal API to it. You'll need this to provide support
+	  for the flash related features of a LED device. It can be built
+	  as a module.
+
 comment "LED drivers"
 
 config LEDS_88PM860X
diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
index d8cc5f2..9238b8a 100644
--- a/drivers/leds/Makefile
+++ b/drivers/leds/Makefile
@@ -2,6 +2,7 @@
 # LED Core
 obj-$(CONFIG_NEW_LEDS)			+= led-core.o
 obj-$(CONFIG_LEDS_CLASS)		+= led-class.o
+obj-$(CONFIG_LEDS_CLASS_FLASH)		+= led-class-flash.o
 obj-$(CONFIG_LEDS_TRIGGERS)		+= led-triggers.o
 
 # LED Platform Drivers
diff --git a/drivers/leds/led-class-flash.c b/drivers/leds/led-class-flash.c
new file mode 100644
index 0000000..4132769
--- /dev/null
+++ b/drivers/leds/led-class-flash.c
@@ -0,0 +1,645 @@
+/*
+ * LED Flash Class interface
+ *
+ * Copyright (C) 2014 Samsung Electronics Co., Ltd.
+ * Author: Jacek Anaszewski <j.anaszewski@samsung.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/device.h>
+#include <linux/init.h>
+#include <linux/leds.h>
+#include <linux/led-class-flash.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include "leds.h"
+
+#define has_flash_op(flash, op)				\
+	(flash && flash->ops->op)
+
+#define call_flash_op(flash, op, args...)		\
+	((has_flash_op(flash, op)) ?			\
+			(flash->ops->op(flash, args)) :	\
+			-EINVAL)
+
+static ssize_t flash_brightness_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t size)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct led_classdev_flash *flash = lcdev_to_flash(led_cdev);
+	unsigned long state;
+	ssize_t ret;
+
+	mutex_lock(&led_cdev->led_lock);
+
+	if (led_sysfs_is_locked(led_cdev)) {
+		ret = -EBUSY;
+		goto unlock;
+	}
+
+	ret = kstrtoul(buf, 10, &state);
+	if (ret)
+		goto unlock;
+
+	ret = led_set_flash_brightness(flash, state);
+	if (ret < 0)
+		goto unlock;
+
+	ret = size;
+unlock:
+	mutex_unlock(&led_cdev->led_lock);
+	return ret;
+}
+
+static ssize_t flash_brightness_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct led_classdev_flash *flash = lcdev_to_flash(led_cdev);
+
+	/* no lock needed for this */
+	led_update_flash_brightness(flash);
+
+	return sprintf(buf, "%u\n", flash->brightness.val);
+}
+static DEVICE_ATTR_RW(flash_brightness);
+
+static ssize_t max_flash_brightness_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct led_classdev_flash *flash = lcdev_to_flash(led_cdev);
+
+	return sprintf(buf, "%u\n", flash->brightness.max);
+}
+static DEVICE_ATTR_RO(max_flash_brightness);
+
+static ssize_t indicator_brightness_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t size)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct led_classdev_flash *flash = lcdev_to_flash(led_cdev);
+	unsigned long state;
+	ssize_t ret;
+
+	mutex_lock(&led_cdev->led_lock);
+
+	if (led_sysfs_is_locked(led_cdev)) {
+		ret = -EBUSY;
+		goto unlock;
+	}
+
+	ret = kstrtoul(buf, 10, &state);
+	if (ret)
+		goto unlock;
+
+	ret = led_set_indicator_brightness(flash, state);
+	if (ret < 0)
+		goto unlock;
+
+	ret = size;
+unlock:
+	mutex_unlock(&led_cdev->led_lock);
+	return ret;
+}
+
+static ssize_t indicator_brightness_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct led_classdev_flash *flash = lcdev_to_flash(led_cdev);
+
+	/* no lock needed for this */
+	led_update_indicator_brightness(flash);
+
+	return sprintf(buf, "%u\n", flash->indicator_brightness->val);
+}
+static DEVICE_ATTR_RW(indicator_brightness);
+
+static ssize_t max_indicator_brightness_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct led_classdev_flash *flash = lcdev_to_flash(led_cdev);
+
+	return sprintf(buf, "%u\n", flash->indicator_brightness->max);
+}
+static DEVICE_ATTR_RO(max_indicator_brightness);
+
+static ssize_t flash_strobe_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t size)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct led_classdev_flash *flash = lcdev_to_flash(led_cdev);
+	unsigned long state;
+	ssize_t ret = -EINVAL;
+
+	mutex_lock(&led_cdev->led_lock);
+
+	if (led_sysfs_is_locked(led_cdev)) {
+		ret = -EBUSY;
+		goto unlock;
+	}
+
+	ret = kstrtoul(buf, 10, &state);
+	if (ret)
+		goto unlock;
+
+	if (state < 0 || state > 1) {
+		ret = -EINVAL;
+		goto unlock;
+	}
+
+	ret = led_set_flash_strobe(flash, state);
+	if (ret < 0)
+		goto unlock;
+	ret = size;
+unlock:
+	mutex_unlock(&led_cdev->led_lock);
+	return ret;
+}
+
+static ssize_t flash_strobe_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct led_classdev_flash *flash = lcdev_to_flash(led_cdev);
+	bool state;
+	int ret;
+
+	/* no lock needed for this */
+	ret = led_get_flash_strobe(flash, &state);
+	if (ret < 0)
+		return ret;
+
+	return sprintf(buf, "%u\n", state);
+}
+static DEVICE_ATTR_RW(flash_strobe);
+
+static ssize_t flash_timeout_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t size)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct led_classdev_flash *flash = lcdev_to_flash(led_cdev);
+	unsigned long flash_timeout;
+	ssize_t ret;
+
+	mutex_lock(&led_cdev->led_lock);
+
+	if (led_sysfs_is_locked(led_cdev)) {
+		ret = -EBUSY;
+		goto unlock;
+	}
+
+	ret = kstrtoul(buf, 10, &flash_timeout);
+	if (ret)
+		goto unlock;
+
+	ret = led_set_flash_timeout(flash, flash_timeout);
+	if (ret < 0)
+		goto unlock;
+
+	ret = size;
+unlock:
+	mutex_unlock(&led_cdev->led_lock);
+	return ret;
+}
+
+static ssize_t flash_timeout_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct led_classdev_flash *flash = lcdev_to_flash(led_cdev);
+
+	return sprintf(buf, "%u\n", flash->timeout.val);
+}
+static DEVICE_ATTR_RW(flash_timeout);
+
+static ssize_t max_flash_timeout_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct led_classdev_flash *flash = lcdev_to_flash(led_cdev);
+
+	return sprintf(buf, "%u\n", flash->timeout.max);
+}
+static DEVICE_ATTR_RO(max_flash_timeout);
+
+static ssize_t flash_fault_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct led_classdev_flash *flash = lcdev_to_flash(led_cdev);
+	u32 fault;
+	int ret;
+
+	ret = led_get_flash_fault(flash, &fault);
+	if (ret < 0)
+		return -EINVAL;
+
+	return sprintf(buf, "0x%8.8x\n", fault);
+}
+static DEVICE_ATTR_RO(flash_fault);
+
+static ssize_t external_strobe_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t size)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct led_classdev_flash *flash = lcdev_to_flash(led_cdev);
+	unsigned long external_strobe;
+	ssize_t ret;
+
+	mutex_lock(&led_cdev->led_lock);
+
+	if (led_sysfs_is_locked(led_cdev)) {
+		ret = -EBUSY;
+		goto unlock;
+	}
+
+	ret = kstrtoul(buf, 10, &external_strobe);
+	if (ret)
+		goto unlock;
+
+	if (external_strobe > 1) {
+		ret = -EINVAL;
+		goto unlock;
+	}
+
+	ret = led_set_external_strobe(flash, external_strobe);
+	if (ret < 0)
+		goto unlock;
+	ret = size;
+unlock:
+	mutex_unlock(&led_cdev->led_lock);
+	return ret;
+}
+
+static ssize_t external_strobe_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct led_classdev_flash *flash = lcdev_to_flash(led_cdev);
+
+	return sprintf(buf, "%u\n", flash->external_strobe);
+}
+static DEVICE_ATTR_RW(external_strobe);
+
+static struct attribute *led_flash_strobe_attrs[] = {
+	&dev_attr_flash_strobe.attr,
+	NULL,
+};
+
+static struct attribute *led_flash_indicator_attrs[] = {
+	&dev_attr_indicator_brightness.attr,
+	&dev_attr_max_indicator_brightness.attr,
+	NULL,
+};
+
+static struct attribute *led_flash_timeout_attrs[] = {
+	&dev_attr_flash_timeout.attr,
+	&dev_attr_max_flash_timeout.attr,
+	NULL,
+};
+
+static struct attribute *led_flash_brightness_attrs[] = {
+	&dev_attr_flash_brightness.attr,
+	&dev_attr_max_flash_brightness.attr,
+	NULL,
+};
+
+static struct attribute *led_flash_external_strobe_attrs[] = {
+	&dev_attr_external_strobe.attr,
+	NULL,
+};
+
+static struct attribute *led_flash_fault_attrs[] = {
+	&dev_attr_flash_fault.attr,
+	NULL,
+};
+
+static struct attribute_group led_flash_strobe_group = {
+	.attrs = led_flash_strobe_attrs,
+};
+
+static struct attribute_group led_flash_brightness_group = {
+	.attrs = led_flash_brightness_attrs,
+};
+
+static struct attribute_group led_flash_timeout_group = {
+	.attrs = led_flash_timeout_attrs,
+};
+
+static struct attribute_group led_flash_indicator_group = {
+	.attrs = led_flash_indicator_attrs,
+};
+
+static struct attribute_group led_flash_fault_group = {
+	.attrs = led_flash_fault_attrs,
+};
+
+static struct attribute_group led_flash_external_strobe_group = {
+	.attrs = led_flash_external_strobe_attrs,
+};
+
+static void led_flash_resume(struct led_classdev *led_cdev)
+{
+	struct led_classdev_flash *flash = lcdev_to_flash(led_cdev);
+
+	call_flash_op(flash, flash_brightness_set, flash->brightness.val);
+	call_flash_op(flash, timeout_set, flash->timeout.val);
+	call_flash_op(flash, indicator_brightness_set,
+				flash->indicator_brightness->val);
+}
+
+static void led_flash_remove_sysfs_groups(struct led_classdev_flash *flash)
+{
+	struct led_classdev *led_cdev = &flash->led_cdev;
+	int i;
+
+	for (i = 0; i < LED_FLASH_MAX_SYSFS_GROUPS; ++i)
+		if (flash->sysfs_groups[i])
+			sysfs_remove_group(&led_cdev->dev->kobj,
+						flash->sysfs_groups[i]);
+}
+
+static int led_flash_create_sysfs_groups(struct led_classdev_flash *flash)
+{
+	struct led_classdev *led_cdev = &flash->led_cdev;
+	const struct led_flash_ops *ops = flash->ops;
+	int ret, num_sysfs_groups = 0;
+
+	memset(flash->sysfs_groups, 0, sizeof(*flash->sysfs_groups) *
+						LED_FLASH_MAX_SYSFS_GROUPS);
+
+	ret = sysfs_create_group(&led_cdev->dev->kobj, &led_flash_strobe_group);
+	if (ret < 0)
+		goto err_create_group;
+	flash->sysfs_groups[num_sysfs_groups++] = &led_flash_strobe_group;
+
+	if (flash->indicator_brightness) {
+		ret = sysfs_create_group(&led_cdev->dev->kobj,
+					&led_flash_indicator_group);
+		if (ret < 0)
+			goto err_create_group;
+		flash->sysfs_groups[num_sysfs_groups++] =
+					&led_flash_indicator_group;
+	}
+
+	if (ops->flash_brightness_set) {
+		ret = sysfs_create_group(&led_cdev->dev->kobj,
+					&led_flash_brightness_group);
+		if (ret < 0)
+			goto err_create_group;
+		flash->sysfs_groups[num_sysfs_groups++] =
+					&led_flash_brightness_group;
+	}
+
+	if (ops->timeout_set) {
+		ret = sysfs_create_group(&led_cdev->dev->kobj,
+					&led_flash_timeout_group);
+		if (ret < 0)
+			goto err_create_group;
+		flash->sysfs_groups[num_sysfs_groups++] =
+					&led_flash_timeout_group;
+	}
+
+	if (ops->fault_get) {
+		ret = sysfs_create_group(&led_cdev->dev->kobj,
+					&led_flash_fault_group);
+		if (ret < 0)
+			goto err_create_group;
+		flash->sysfs_groups[num_sysfs_groups++] =
+					&led_flash_fault_group;
+	}
+
+	if (flash->has_external_strobe) {
+		ret = sysfs_create_group(&led_cdev->dev->kobj,
+					&led_flash_external_strobe_group);
+		if (ret < 0)
+			goto err_create_group;
+		flash->sysfs_groups[num_sysfs_groups++] =
+					&led_flash_external_strobe_group;
+	}
+
+	return 0;
+
+err_create_group:
+	led_flash_remove_sysfs_groups(flash);
+	return ret;
+}
+
+int led_classdev_flash_register(struct device *parent,
+				struct led_classdev_flash *flash,
+				struct device_node *node)
+{
+	struct led_classdev *led_cdev;
+	const struct led_flash_ops *ops;
+	int ret = -EINVAL;
+
+	if (!flash)
+		return -EINVAL;
+
+	led_cdev = &flash->led_cdev;
+
+	/* Torch capability is default for every LED Flash Class device */
+	led_cdev->flags |= LED_DEV_CAP_TORCH;
+
+	if (led_cdev->flags & LED_DEV_CAP_FLASH) {
+		if (!led_cdev->torch_brightness_set)
+			return -EINVAL;
+
+		ops = flash->ops;
+		if (!ops || !ops->strobe_set)
+			return -EINVAL;
+
+		if ((led_cdev->flags & LED_DEV_CAP_INDICATOR) &&
+		    (!flash->indicator_brightness ||
+		     !ops->indicator_brightness_set))
+			return -EINVAL;
+
+		led_cdev->flash_resume = led_flash_resume;
+	}
+
+	/* Register led class device */
+	ret = led_classdev_register(parent, led_cdev);
+	if (ret < 0)
+		return -EINVAL;
+
+	/* Create flash led specific sysfs attributes */
+	ret = led_flash_create_sysfs_groups(flash);
+	if (ret < 0)
+		goto err_create_sysfs_groups;
+
+	return 0;
+
+err_create_sysfs_groups:
+	led_classdev_unregister(led_cdev);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(led_classdev_flash_register);
+
+void led_classdev_flash_unregister(struct led_classdev_flash *flash)
+{
+	if (!flash)
+		return;
+
+	led_flash_remove_sysfs_groups(flash);
+	led_classdev_unregister(&flash->led_cdev);
+}
+EXPORT_SYMBOL_GPL(led_classdev_flash_unregister);
+
+int led_set_flash_strobe(struct led_classdev_flash *flash, bool state)
+{
+	if (flash->external_strobe)
+		return -EBUSY;
+
+	return call_flash_op(flash, strobe_set, state);
+}
+EXPORT_SYMBOL_GPL(led_set_flash_strobe);
+
+int led_get_flash_strobe(struct led_classdev_flash *flash, bool *state)
+{
+	return call_flash_op(flash, strobe_get, state);
+}
+EXPORT_SYMBOL_GPL(led_get_flash_strobe);
+
+void led_clamp_align(struct led_flash_setting *s)
+{
+	u32 v, offset;
+
+	v = s->val + s->step / 2;
+	v = clamp(v, s->min, s->max);
+	offset = v - s->min;
+	offset = s->step * (offset / s->step);
+	s->val = s->min + offset;
+}
+
+int led_set_flash_timeout(struct led_classdev_flash *flash, u32 timeout)
+{
+	struct led_classdev *led_cdev = &flash->led_cdev;
+	struct led_flash_setting *s = &flash->timeout;
+	int ret = 0;
+
+	s->val = timeout;
+	led_clamp_align(s);
+
+	if (!(led_cdev->flags & LED_SUSPENDED))
+		ret = call_flash_op(flash, timeout_set, s->val);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(led_set_flash_timeout);
+
+int led_get_flash_fault(struct led_classdev_flash *flash, u32 *fault)
+{
+	return call_flash_op(flash, fault_get, fault);
+}
+EXPORT_SYMBOL_GPL(led_get_flash_fault);
+
+int led_set_external_strobe(struct led_classdev_flash *flash, bool enable)
+{
+	int ret;
+
+	if (flash->has_external_strobe) {
+		/*
+		 * Some flash led devices need altering their register
+		 * settings to start listen to the external strobe signal.
+		 */
+		if (has_flash_op(flash, external_strobe_set)) {
+			ret = call_flash_op(flash, external_strobe_set, enable);
+			if (ret < 0)
+				return ret;
+		}
+
+		flash->external_strobe = enable;
+	} else if (enable) {
+		return -EINVAL;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(led_set_external_strobe);
+
+int led_set_flash_brightness(struct led_classdev_flash *flash,
+				u32 brightness)
+{
+	struct led_classdev *led_cdev = &flash->led_cdev;
+	struct led_flash_setting *s = &flash->brightness;
+	int ret = 0;
+
+	s->val = brightness;
+	led_clamp_align(s);
+
+	if (!(led_cdev->flags & LED_SUSPENDED))
+		ret = call_flash_op(flash, flash_brightness_set, s->val);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(led_set_flash_brightness);
+
+int led_update_flash_brightness(struct led_classdev_flash *flash)
+{
+	struct led_flash_setting *s = &flash->brightness;
+	u32 brightness;
+	int ret = 0;
+
+	if (has_flash_op(flash, flash_brightness_get)) {
+		ret = call_flash_op(flash, flash_brightness_get,
+						&brightness);
+		if (ret < 0)
+			return ret;
+		s->val = brightness;
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(led_update_flash_brightness);
+
+int led_set_indicator_brightness(struct led_classdev_flash *flash,
+					u32 brightness)
+{
+	struct led_classdev *led_cdev = &flash->led_cdev;
+	struct led_flash_setting *s = flash->indicator_brightness;
+	int ret = 0;
+
+	if (!s)
+		return -EINVAL;
+
+	s->val = brightness;
+	led_clamp_align(s);
+
+	if (!(led_cdev->flags & LED_SUSPENDED))
+		ret = call_flash_op(flash, indicator_brightness_set, s->val);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(led_set_indicator_brightness);
+
+int led_update_indicator_brightness(struct led_classdev_flash *flash)
+{
+	struct led_flash_setting *s = flash->indicator_brightness;
+	u32 brightness;
+	int ret = 0;
+
+	if (!s)
+		return -EINVAL;
+
+	if (has_flash_op(flash, indicator_brightness_get)) {
+		ret = call_flash_op(flash, indicator_brightness_get,
+							&brightness);
+		if (ret < 0)
+			return ret;
+		s->val = brightness;
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(led_update_indicator_brightness);
+
+MODULE_AUTHOR("Jacek Anaszewski <j.anaszewski@samsung.com>");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("LED Flash Class Interface");
diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index f640da9..86a03a0 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -189,6 +189,10 @@ EXPORT_SYMBOL_GPL(led_classdev_suspend);
 void led_classdev_resume(struct led_classdev *led_cdev)
 {
 	led_cdev->brightness_set(led_cdev, led_cdev->brightness);
+
+	if (led_cdev->flash_resume)
+		led_cdev->flash_resume(led_cdev);
+
 	led_cdev->flags &= ~LED_SUSPENDED;
 }
 EXPORT_SYMBOL_GPL(led_classdev_resume);
diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c
index d391a5d..d80a8f3 100644
--- a/drivers/leds/led-triggers.c
+++ b/drivers/leds/led-triggers.c
@@ -43,6 +43,11 @@ ssize_t led_trigger_store(struct device *dev, struct device_attribute *attr,
 	mutex_lock(&led_cdev->led_lock);
 #endif
 
+	if (led_sysfs_is_locked(led_cdev)) {
+		ret = -EBUSY;
+		goto exit_unlock;
+	}
+
 	trigger_name[sizeof(trigger_name) - 1] = '\0';
 	strncpy(trigger_name, buf, sizeof(trigger_name) - 1);
 	len = strlen(trigger_name);
diff --git a/include/linux/led-class-flash.h b/include/linux/led-class-flash.h
new file mode 100644
index 0000000..a882263
--- /dev/null
+++ b/include/linux/led-class-flash.h
@@ -0,0 +1,273 @@
+/*
+ * LED Flash Class interface
+ *
+ * Copyright (C) 2014 Samsung Electronics Co., Ltd.
+ * Author: Jacek Anaszewski <j.anaszewski@samsung.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+#ifndef __LINUX_FLASH_LEDS_H_INCLUDED
+#define __LINUX_FLASH_LEDS_H_INCLUDED
+
+#include <linux/leds.h>
+
+struct led_classdev_flash;
+struct device_node;
+
+/*
+ * Supported led fault bits - must be kept in synch
+ * with V4L2_FLASH_FAULT bits.
+ */
+#define LED_FAULT_OVER_VOLTAGE		 V4L2_FLASH_FAULT_OVER_VOLTAGE
+#define LED_FAULT_TIMEOUT		 V4L2_FLASH_FAULT_TIMEOUT
+#define LED_FAULT_OVER_TEMPERATURE	 V4L2_FLASH_FAULT_OVER_TEMPERATURE
+#define LED_FAULT_SHORT_CIRCUIT		 V4L2_FLASH_FAULT_SHORT_CIRCUIT
+#define LED_FAULT_OVER_CURRENT		 V4L2_FLASH_FAULT_OVER_CURRENT
+#define LED_FAULT_INDICATOR		 V4L2_FLASH_FAULT_INDICATOR
+#define LED_FAULT_UNDER_VOLTAGE		 V4L2_FLASH_FAULT_UNDER_VOLTAGE
+#define LED_FAULT_INPUT_VOLTAGE		 V4L2_FLASH_FAULT_INPUT_VOLTAGE
+#define LED_FAULT_LED_OVER_TEMPERATURE	 V4L2_FLASH_OVER_TEMPERATURE
+
+#define LED_FLASH_MAX_SYSFS_GROUPS 6
+
+struct led_flash_ops {
+	/* set flash brightness */
+	int (*flash_brightness_set)(struct led_classdev_flash *flash,
+					u32 brightness);
+	/* get flash brightness */
+	int (*flash_brightness_get)(struct led_classdev_flash *flash,
+					u32 *brightness);
+	/* set flash indicator brightness */
+	int (*indicator_brightness_set)(struct led_classdev_flash *flash,
+					u32 brightness);
+	/* get flash indicator brightness */
+	int (*indicator_brightness_get)(struct led_classdev_flash *flash,
+					u32 *brightness);
+	/* set flash strobe state */
+	int (*strobe_set)(struct led_classdev_flash *flash, bool state);
+	/* get flash strobe state */
+	int (*strobe_get)(struct led_classdev_flash *flash, bool *state);
+	/* set flash timeout */
+	int (*timeout_set)(struct led_classdev_flash *flash, u32 timeout);
+	/* setup the device to strobe the flash upon a pin state assertion */
+	int (*external_strobe_set)(struct led_classdev_flash *flash,
+					bool enable);
+	/* get the flash LED fault */
+	int (*fault_get)(struct led_classdev_flash *flash, u32 *fault);
+};
+
+/*
+ * Current value of a flash setting along
+ * with its constraints.
+ */
+struct led_flash_setting {
+	/* maximum allowed value */
+	u32 min;
+	/* maximum allowed value */
+	u32 max;
+	/* step value */
+	u32 step;
+	/* current value */
+	u32 val;
+};
+
+/*
+ * Aggregated flash settings - designed for ease
+ * of passing initialization data to the clients
+ * wrapping a LED Flash class device.
+ */
+struct led_flash_config {
+	struct led_flash_setting torch_brightness;
+	struct led_flash_setting flash_brightness;
+	struct led_flash_setting indicator_brightness;
+	struct led_flash_setting flash_timeout;
+	u32 flash_faults;
+};
+
+struct led_classdev_flash {
+	/* led-flash-manager uses it to link flashes */
+	struct list_head list;
+	/* led class device */
+	struct led_classdev led_cdev;
+	/* flash led specific ops */
+	const struct led_flash_ops *ops;
+
+	/* flash sysfs groups */
+	struct attribute_group *sysfs_groups[LED_FLASH_MAX_SYSFS_GROUPS];
+
+	/* flash brightness value in microamperes along with its constraints */
+	struct led_flash_setting brightness;
+
+	/* timeout value in microseconds along with its constraints */
+	struct led_flash_setting timeout;
+
+	/*
+	 * Indicator brightness value in microamperes along with
+	 * its constraints - this is an optional setting and must
+	 * be allocated by the driver if the device supports privacy
+	 * indicator led.
+	 */
+	struct led_flash_setting *indicator_brightness;
+
+	/*
+	 * determines if a device supports external
+	 * flash strobe sources
+	 */
+	bool has_external_strobe;
+
+	/* If true the flash led is strobed from external source */
+	bool external_strobe;
+
+	/* Flash manager data */
+	/* Strobe signals topology data */
+	struct list_head software_strobe_gates;
+	struct list_head strobe_providers;
+
+	/* identifier of the selected strobe signal provider */
+	int strobe_provider_id;
+
+	/* number of defined strobe providers */
+	int num_strobe_providers;
+};
+
+static inline struct led_classdev_flash *lcdev_to_flash(
+						struct led_classdev *lcdev)
+{
+	return container_of(lcdev, struct led_classdev_flash, led_cdev);
+}
+
+/**
+ * led_classdev_flash_register - register a new object of led_classdev class
+				 with support for flash LEDs
+ * @parent: the flash LED to register
+ * @flash: the led_classdev_flash structure for this device
+ * @node: device tree node of the LED Flash Class device - it must be
+	  initialized if the device is to be registered in the flash manager
+ *
+ * Returns: 0 on success or negative error value on failure
+ */
+int led_classdev_flash_register(struct device *parent,
+				struct led_classdev_flash *flash,
+				struct device_node *node);
+
+/**
+ * led_classdev_flash_unregister - unregisters an object of led_classdev class
+				   with support for flash LEDs
+ * @flash: the flash LED to unregister
+ *
+ * Unregisters a previously registered via led_classdev_flash_register object
+ */
+void led_classdev_flash_unregister(struct led_classdev_flash *flash);
+
+/**
+ * led_set_flash_strobe - setup flash strobe
+ * @flash: the flash LED to set strobe on
+ * @state: 1 - strobe flash, 0 - stop flash strobe
+ *
+ * Setup flash strobe - trigger flash strobe
+ *
+ * Returns: 0 on success or negative error value on failure
+ */
+extern int led_set_flash_strobe(struct led_classdev_flash *flash,
+				bool state);
+
+/**
+ * led_get_flash_strobe - get flash strobe status
+ * @flash: the flash LED to query
+ * @state: 1 - flash is strobing, 0 - flash is off
+ *
+ * Check whether the flash is strobing at the moment or not.
+ *
+u* Returns: 0 on success or negative error value on failure
+ */
+extern int led_get_flash_strobe(struct led_classdev_flash *flash,
+				bool *state);
+/**
+ * led_set_flash_brightness - set flash LED brightness
+ * @flash: the flash LED to set
+ * @brightness: the brightness to set it to
+ *
+ * Returns: 0 on success or negative error value on failure
+ *
+ * Set a flash LED's brightness.
+ */
+extern int led_set_flash_brightness(struct led_classdev_flash *flash,
+					u32 brightness);
+
+/**
+ * led_update_flash_brightness - update flash LED brightness
+ * @flash: the flash LED to query
+ *
+ * Get a flash LED's current brightness and update led_flash->brightness
+ * member with the obtained value.
+ *
+ * Returns: 0 on success or negative error value on failure
+ */
+extern int led_update_flash_brightness(struct led_classdev_flash *flash);
+
+/**
+ * led_set_flash_timeout - set flash LED timeout
+ * @flash: the flash LED to set
+ * @timeout: the flash timeout to set it to
+ *
+ * Set the flash strobe duration. The duration set by the driver
+ * is returned in the timeout argument and may differ from the
+ * one that was originally passed.
+ *
+ * Returns: 0 on success or negative error value on failure
+ */
+extern int led_set_flash_timeout(struct led_classdev_flash *flash,
+					u32 timeout);
+
+/**
+ * led_get_flash_fault - get the flash LED fault
+ * @flash: the flash LED to query
+ * @fault: bitmask containing flash faults
+ *
+ * Get the flash LED fault.
+ *
+ * Returns: 0 on success or negative error value on failure
+ */
+extern int led_get_flash_fault(struct led_classdev_flash *flash,
+					u32 *fault);
+
+/**
+ * led_set_external_strobe - set the flash LED external_strobe mode
+ * @flash: the flash LED to set
+ * @enable: the state to set it to
+ *
+ * Enable/disable strobing the flash LED with use of external source
+ *
+  Returns: 0 on success or negative error value on failure
+ */
+extern int led_set_external_strobe(struct led_classdev_flash *flash,
+					bool enable);
+
+/**
+ * led_set_indicator_brightness - set indicator LED brightness
+ * @flash: the flash LED to set
+ * @brightness: the brightness to set it to
+ *
+ * Set an indicator LED's brightness.
+ *
+ * Returns: 0 on success or negative error value on failure
+ */
+extern int led_set_indicator_brightness(struct led_classdev_flash *flash,
+					u32 led_brightness);
+
+/**
+ * led_update_indicator_brightness - update flash indicator LED brightness
+ * @flash: the flash LED to query
+ *
+ * Get a flash indicator LED's current brightness and update
+ * led_flash->indicator_brightness member with the obtained value.
+ *
+ * Returns: 0 on success or negative error value on failure
+ */
+extern int led_update_indicator_brightness(struct led_classdev_flash *flash);
+
+
+#endif	/* __LINUX_FLASH_LEDS_H_INCLUDED */
diff --git a/include/linux/leds.h b/include/linux/leds.h
index df0715c..8e38eef 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -44,6 +44,8 @@ struct led_classdev {
 #define LED_BLINK_INVERT	(1 << 19)
 #define LED_SYSFS_LOCK		(1 << 20)
 #define LED_DEV_CAP_TORCH	(1 << 21)
+#define LED_DEV_CAP_FLASH	(1 << 22)
+#define LED_DEV_CAP_INDICATOR	(1 << 23)
 
 	/* Set LED brightness level */
 	/* Must not sleep, use a workqueue if needed */
@@ -82,6 +84,7 @@ struct led_classdev {
 	unsigned long		 blink_delay_on, blink_delay_off;
 	struct delayed_work	 blink_work;
 	int			 blink_brightness;
+	void			(*flash_resume)(struct led_classdev *led_cdev);
 
 	struct work_struct	set_brightness_work;
 	int			delayed_set_value;
-- 
1.7.9.5

Re: [PATCH/RFC v5 1/4] leds: Improve and export led_update_brightness

[Bryan Wu]

On Wed, Aug 20, 2014 at 6:41 AM, Jacek Anaszewski
<j.anaszewski@samsung.com> wrote:
> led_update_brightness helper function used to be exploited only locally
> in the led-class.c module, where its result was being passed to the
> brightness_show sysfs callback. With the introduction of v4l2-flash
> subdevice the same functionality becomes required for reading current
> brightness from a LED device. This patch adds checking of return value
> of the brightness_get callback and moves the led_update_brightness()
> function to the LED subsystem public API.
>

This one looks good to me.
Thanks,
-Bryan

> Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
> Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
> Cc: Bryan Wu <cooloney@gmail.com>
> Cc: Richard Purdie <rpurdie@rpsys.net>
> ---
>  drivers/leds/led-class.c |    6 ------
>  drivers/leds/led-core.c  |   16 ++++++++++++++++
>  include/linux/leds.h     |   10 ++++++++++
>  3 files changed, 26 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
> index f4e5bb4..6f82a76 100644
> --- a/drivers/leds/led-class.c
> +++ b/drivers/leds/led-class.c
> @@ -23,12 +23,6 @@
>
>  static struct class *leds_class;
>
> -static void led_update_brightness(struct led_classdev *led_cdev)
> -{
> -       if (led_cdev->brightness_get)
> -               led_cdev->brightness = led_cdev->brightness_get(led_cdev);
> -}
> -
>  static ssize_t brightness_show(struct device *dev,
>                 struct device_attribute *attr, char *buf)
>  {
> diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
> index 8380eb7..466ce5a 100644
> --- a/drivers/leds/led-core.c
> +++ b/drivers/leds/led-core.c
> @@ -127,3 +127,19 @@ void led_set_brightness(struct led_classdev *led_cdev,
>         __led_set_brightness(led_cdev, brightness);
>  }
>  EXPORT_SYMBOL(led_set_brightness);
> +
> +int led_update_brightness(struct led_classdev *led_cdev)
> +{
> +       int ret = 0;
> +
> +       if (led_cdev->brightness_get) {
> +               ret = led_cdev->brightness_get(led_cdev);
> +               if (ret >= 0) {
> +                       led_cdev->brightness = ret;
> +                       return 0;
> +               }
> +       }
> +
> +       return ret;
> +}
> +EXPORT_SYMBOL(led_update_brightness);
> diff --git a/include/linux/leds.h b/include/linux/leds.h
> index bc221d11..cc85b16 100644
> --- a/include/linux/leds.h
> +++ b/include/linux/leds.h
> @@ -139,6 +139,16 @@ extern void led_blink_set_oneshot(struct led_classdev *led_cdev,
>   */
>  extern void led_set_brightness(struct led_classdev *led_cdev,
>                                enum led_brightness brightness);
> +/**
> + * led_update_brightness - update LED brightness
> + * @led_cdev: the LED to query
> + *
> + * Get an LED's current brightness and update led_cdev->brightness
> + * member with the obtained value.
> + *
> + * Returns: 0 on success or negative error value on failure
> + */
> +extern int led_update_brightness(struct led_classdev *led_cdev);
>
>  /*
>   * LED Triggers
> --
> 1.7.9.5
>

Re: [PATCH/RFC v5 2/4] leds: implement sysfs interface locking mechanism

[Bryan Wu]

On Wed, Aug 20, 2014 at 6:41 AM, Jacek Anaszewski
<j.anaszewski@samsung.com> wrote:
> Add a mechanism for locking LED subsystem sysfs interface.
> This patch prepares ground for addition of LED Flash Class
> extension, whose API will be integrated with V4L2 Flash API.
> Such a fusion enforces introducing a locking scheme, which
> will secure consistent access to the LED Flash Class device.
>
> The mechanism being introduced allows for disabling LED
> subsystem sysfs interface by calling led_sysfs_lock function
> and enabling it by calling led_sysfs_unlock. The functions
> alter the LED_SYSFS_LOCK flag state and must be called
> under mutex lock. The state of the lock is checked with use
> of led_sysfs_is_locked function. Such a design allows for
> providing immediate feedback to the user space on whether
> the LED Flash Class device is available or is under V4L2 Flash
> sub-device control.
>
> Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
> Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
> Cc: Bryan Wu <cooloney@gmail.com>
> Cc: Richard Purdie <rpurdie@rpsys.net>
> ---
>  drivers/leds/led-class.c    |   23 ++++++++++++++++++++---
>  drivers/leds/led-core.c     |   18 ++++++++++++++++++
>  drivers/leds/led-triggers.c |   15 ++++++++++++---
>  include/linux/leds.h        |   32 ++++++++++++++++++++++++++++++++
>  4 files changed, 82 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
> index 6f82a76..0bc0ba9 100644
> --- a/drivers/leds/led-class.c
> +++ b/drivers/leds/led-class.c
> @@ -39,17 +39,31 @@ static ssize_t brightness_store(struct device *dev,
>  {
>         struct led_classdev *led_cdev = dev_get_drvdata(dev);
>         unsigned long state;
> -       ssize_t ret = -EINVAL;
> +       ssize_t ret;
> +
> +#ifdef CONFIG_V4L2_FLASH_LED_CLASS

Can we remove this #ifdef? Following code looks good to the common LED class.

> +       mutex_lock(&led_cdev->led_lock);

Can we choose more meaningful name instead of led_lock here?
Then use led_sysfs_enable() instead of led_sysfs_unlock()
led_sysfs_disable instead of led_sysfs_lock()
led_sysfs_is_disabled instead of led_sysfs_is_locked()

And the flag LED_SYSFS_LOCK -> LED_SYSFS_DISABLE

I was just confused by the name lock and unlock and mutex lock.

The idea looks good to me.

Thanks,
-Bryan

> +
> +       if (led_sysfs_is_locked(led_cdev)) {
> +               ret = -EBUSY;
> +               goto unlock;
> +       }
> +#endif
>
>         ret = kstrtoul(buf, 10, &state);
>         if (ret)
> -               return ret;
> +               goto unlock;
>
>         if (state == LED_OFF)
>                 led_trigger_remove(led_cdev);
>         __led_set_brightness(led_cdev, state);
>
> -       return size;
> +       ret = size;
> +unlock:
> +#ifdef CONFIG_V4L2_FLASH_LED_CLASS
> +       mutex_unlock(&led_cdev->led_lock);
> +#endif
> +       return ret;
>  }
>  static DEVICE_ATTR_RW(brightness);
>
> @@ -215,6 +229,7 @@ int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
>  #ifdef CONFIG_LEDS_TRIGGERS
>         init_rwsem(&led_cdev->trigger_lock);
>  #endif
> +       mutex_init(&led_cdev->led_lock);
>         /* add to the list of leds */
>         down_write(&leds_list_lock);
>         list_add_tail(&led_cdev->node, &leds_list);
> @@ -266,6 +281,8 @@ void led_classdev_unregister(struct led_classdev *led_cdev)
>         down_write(&leds_list_lock);
>         list_del(&led_cdev->node);
>         up_write(&leds_list_lock);
> +
> +       mutex_destroy(&led_cdev->led_lock);
>  }
>  EXPORT_SYMBOL_GPL(led_classdev_unregister);
>
> diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
> index 466ce5a..4649ea5 100644
> --- a/drivers/leds/led-core.c
> +++ b/drivers/leds/led-core.c
> @@ -143,3 +143,21 @@ int led_update_brightness(struct led_classdev *led_cdev)
>         return ret;
>  }
>  EXPORT_SYMBOL(led_update_brightness);
> +
> +/* Caller must ensure led_cdev->led_lock held */
> +void led_sysfs_lock(struct led_classdev *led_cdev)
> +{
> +       lockdep_assert_held(&led_cdev->led_lock);
> +
> +       led_cdev->flags |= LED_SYSFS_LOCK;
> +}
> +EXPORT_SYMBOL_GPL(led_sysfs_lock);
> +
> +/* Caller must ensure led_cdev->led_lock held */
> +void led_sysfs_unlock(struct led_classdev *led_cdev)
> +{
> +       lockdep_assert_held(&led_cdev->led_lock);
> +
> +       led_cdev->flags &= ~LED_SYSFS_LOCK;
> +}
> +EXPORT_SYMBOL_GPL(led_sysfs_unlock);
> diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c
> index c3734f1..d391a5d 100644
> --- a/drivers/leds/led-triggers.c
> +++ b/drivers/leds/led-triggers.c
> @@ -37,6 +37,11 @@ ssize_t led_trigger_store(struct device *dev, struct device_attribute *attr,
>         char trigger_name[TRIG_NAME_MAX];
>         struct led_trigger *trig;
>         size_t len;
> +       int ret = count;
> +
> +#ifdef CONFIG_V4L2_FLASH_LED_CLASS
> +       mutex_lock(&led_cdev->led_lock);
> +#endif
>
>         trigger_name[sizeof(trigger_name) - 1] = '\0';
>         strncpy(trigger_name, buf, sizeof(trigger_name) - 1);
> @@ -47,7 +52,7 @@ ssize_t led_trigger_store(struct device *dev, struct device_attribute *attr,
>
>         if (!strcmp(trigger_name, "none")) {
>                 led_trigger_remove(led_cdev);
> -               return count;
> +               goto exit_unlock;
>         }
>
>         down_read(&triggers_list_lock);
> @@ -58,12 +63,16 @@ ssize_t led_trigger_store(struct device *dev, struct device_attribute *attr,
>                         up_write(&led_cdev->trigger_lock);
>
>                         up_read(&triggers_list_lock);
> -                       return count;
> +                       goto exit_unlock;
>                 }
>         }
>         up_read(&triggers_list_lock);
>
> -       return -EINVAL;
> +exit_unlock:
> +#ifdef CONFIG_V4L2_FLASH_LED_CLASS
> +       mutex_unlock(&led_cdev->led_lock);
> +#endif
> +       return ret;
>  }
>  EXPORT_SYMBOL_GPL(led_trigger_store);
>
> diff --git a/include/linux/leds.h b/include/linux/leds.h
> index cc85b16..ef343f1 100644
> --- a/include/linux/leds.h
> +++ b/include/linux/leds.h
> @@ -13,6 +13,7 @@
>  #define __LINUX_LEDS_H_INCLUDED
>
>  #include <linux/list.h>
> +#include <linux/mutex.h>
>  #include <linux/rwsem.h>
>  #include <linux/spinlock.h>
>  #include <linux/workqueue.h>
> @@ -41,6 +42,7 @@ struct led_classdev {
>  #define LED_BLINK_ONESHOT      (1 << 17)
>  #define LED_BLINK_ONESHOT_STOP (1 << 18)
>  #define LED_BLINK_INVERT       (1 << 19)
> +#define LED_SYSFS_LOCK         (1 << 20)
>
>         /* Set LED brightness level */
>         /* Must not sleep, use a workqueue if needed */
> @@ -84,6 +86,9 @@ struct led_classdev {
>         /* true if activated - deactivate routine uses it to do cleanup */
>         bool                    activated;
>  #endif
> +
> +       /* Ensures consistent access to the LED Flash Class device */
> +       struct mutex            led_lock;
>  };
>
>  extern int led_classdev_register(struct device *parent,
> @@ -150,6 +155,33 @@ extern void led_set_brightness(struct led_classdev *led_cdev,
>   */
>  extern int led_update_brightness(struct led_classdev *led_cdev);
>
> +/**
> + * led_sysfs_lock - lock LED sysfs interface
> + * @led_cdev: the LED to set
> + *
> + * Lock the LED's sysfs interface
> + */
> +extern void led_sysfs_lock(struct led_classdev *led_cdev);
> +
> +/**
> + * led_sysfs_unlock - unlock LED sysfs interface
> + * @led_cdev: the LED to set
> + *
> + * Unlock the LED's sysfs interface
> + */
> +extern void led_sysfs_unlock(struct led_classdev *led_cdev);
> +
> +/**
> + * led_sysfs_is_locked
> + * @led_cdev: the LED to query
> + *
> + * Returns: true if the sysfs interface of the led is locked
> + */
> +static inline bool led_sysfs_is_locked(struct led_classdev *led_cdev)
> +{
> +       return led_cdev->flags & LED_SYSFS_LOCK;
> +}
> +
>  /*
>   * LED Triggers
>   */
> --
> 1.7.9.5
>

Re: [PATCH/RFC v5 2/4] leds: implement sysfs interface locking mechanism

[Jacek Anaszewski]

Hi Bryan,

Thanks for a review.

On 09/12/2014 03:11 AM, Bryan Wu wrote:
> On Wed, Aug 20, 2014 at 6:41 AM, Jacek Anaszewski
> <j.anaszewski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org> wrote:
>> Add a mechanism for locking LED subsystem sysfs interface.
>> This patch prepares ground for addition of LED Flash Class
>> extension, whose API will be integrated with V4L2 Flash API.
>> Such a fusion enforces introducing a locking scheme, which
>> will secure consistent access to the LED Flash Class device.
>>
>> The mechanism being introduced allows for disabling LED
>> subsystem sysfs interface by calling led_sysfs_lock function
>> and enabling it by calling led_sysfs_unlock. The functions
>> alter the LED_SYSFS_LOCK flag state and must be called
>> under mutex lock. The state of the lock is checked with use
>> of led_sysfs_is_locked function. Such a design allows for
>> providing immediate feedback to the user space on whether
>> the LED Flash Class device is available or is under V4L2 Flash
>> sub-device control.
>>
>> Signed-off-by: Jacek Anaszewski <j.anaszewski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
>> Acked-by: Kyungmin Park <kyungmin.park-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
>> Cc: Bryan Wu <cooloney-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>> Cc: Richard Purdie <rpurdie-Fm38FmjxZ/leoWH0uzbU5w@public.gmane.org>
>> ---
>>   drivers/leds/led-class.c    |   23 ++++++++++++++++++++---
>>   drivers/leds/led-core.c     |   18 ++++++++++++++++++
>>   drivers/leds/led-triggers.c |   15 ++++++++++++---
>>   include/linux/leds.h        |   32 ++++++++++++++++++++++++++++++++
>>   4 files changed, 82 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
>> index 6f82a76..0bc0ba9 100644
>> --- a/drivers/leds/led-class.c
>> +++ b/drivers/leds/led-class.c
>> @@ -39,17 +39,31 @@ static ssize_t brightness_store(struct device *dev,
>>   {
>>          struct led_classdev *led_cdev = dev_get_drvdata(dev);
>>          unsigned long state;
>> -       ssize_t ret = -EINVAL;
>> +       ssize_t ret;
>> +
>> +#ifdef CONFIG_V4L2_FLASH_LED_CLASS
>
> Can we remove this #ifdef? Following code looks good to the common LED class.

Sure.

>> +       mutex_lock(&led_cdev->led_lock);
>
> Can we choose more meaningful name instead of led_lock here?
> Then use led_sysfs_enable() instead of led_sysfs_unlock()
> led_sysfs_disable instead of led_sysfs_lock()
> led_sysfs_is_disabled instead of led_sysfs_is_locked()
>
> And the flag LED_SYSFS_LOCK -> LED_SYSFS_DISABLE
>
> I was just confused by the name lock and unlock and mutex lock.
>
> The idea looks good to me.

Indeed, this naming will be more intuitive.

Regards,
Jacek

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Re: [PATCH/RFC v5 2/4] leds: implement sysfs interface locking mechanism

[Jacek Anaszewski]

Hi Bryan,

Thanks for a review.

On 09/12/2014 03:11 AM, Bryan Wu wrote:
> On Wed, Aug 20, 2014 at 6:41 AM, Jacek Anaszewski
> <j.anaszewski@samsung.com> wrote:
>> Add a mechanism for locking LED subsystem sysfs interface.
>> This patch prepares ground for addition of LED Flash Class
>> extension, whose API will be integrated with V4L2 Flash API.
>> Such a fusion enforces introducing a locking scheme, which
>> will secure consistent access to the LED Flash Class device.
>>
>> The mechanism being introduced allows for disabling LED
>> subsystem sysfs interface by calling led_sysfs_lock function
>> and enabling it by calling led_sysfs_unlock. The functions
>> alter the LED_SYSFS_LOCK flag state and must be called
>> under mutex lock. The state of the lock is checked with use
>> of led_sysfs_is_locked function. Such a design allows for
>> providing immediate feedback to the user space on whether
>> the LED Flash Class device is available or is under V4L2 Flash
>> sub-device control.
>>
>> Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
>> Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
>> Cc: Bryan Wu <cooloney@gmail.com>
>> Cc: Richard Purdie <rpurdie@rpsys.net>
>> ---
>>   drivers/leds/led-class.c    |   23 ++++++++++++++++++++---
>>   drivers/leds/led-core.c     |   18 ++++++++++++++++++
>>   drivers/leds/led-triggers.c |   15 ++++++++++++---
>>   include/linux/leds.h        |   32 ++++++++++++++++++++++++++++++++
>>   4 files changed, 82 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
>> index 6f82a76..0bc0ba9 100644
>> --- a/drivers/leds/led-class.c
>> +++ b/drivers/leds/led-class.c
>> @@ -39,17 +39,31 @@ static ssize_t brightness_store(struct device *dev,
>>   {
>>          struct led_classdev *led_cdev = dev_get_drvdata(dev);
>>          unsigned long state;
>> -       ssize_t ret = -EINVAL;
>> +       ssize_t ret;
>> +
>> +#ifdef CONFIG_V4L2_FLASH_LED_CLASS
>
> Can we remove this #ifdef? Following code looks good to the common LED class.

Sure.

>> +       mutex_lock(&led_cdev->led_lock);
>
> Can we choose more meaningful name instead of led_lock here?
> Then use led_sysfs_enable() instead of led_sysfs_unlock()
> led_sysfs_disable instead of led_sysfs_lock()
> led_sysfs_is_disabled instead of led_sysfs_is_locked()
>
> And the flag LED_SYSFS_LOCK -> LED_SYSFS_DISABLE
>
> I was just confused by the name lock and unlock and mutex lock.
>
> The idea looks good to me.

Indeed, this naming will be more intuitive.

Regards,
Jacek

Re: [PATCH/RFC v5 1/4] leds: Improve and export led_update_brightness

[Bryan Wu]

On Fri, Sep 5, 2014 at 2:03 PM, Bryan Wu <cooloney@gmail.com> wrote:
> On Wed, Aug 20, 2014 at 6:41 AM, Jacek Anaszewski
> <j.anaszewski@samsung.com> wrote:
>> led_update_brightness helper function used to be exploited only locally
>> in the led-class.c module, where its result was being passed to the
>> brightness_show sysfs callback. With the introduction of v4l2-flash
>> subdevice the same functionality becomes required for reading current
>> brightness from a LED device. This patch adds checking of return value
>> of the brightness_get callback and moves the led_update_brightness()
>> function to the LED subsystem public API.
>>
>
> This one looks good to me.
> Thanks,
> -Bryan
>

Merged， no need to update this patch then.

-Bryan

>> Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
>> Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
>> Cc: Bryan Wu <cooloney@gmail.com>
>> Cc: Richard Purdie <rpurdie@rpsys.net>
>> ---
>>  drivers/leds/led-class.c |    6 ------
>>  drivers/leds/led-core.c  |   16 ++++++++++++++++
>>  include/linux/leds.h     |   10 ++++++++++
>>  3 files changed, 26 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
>> index f4e5bb4..6f82a76 100644
>> --- a/drivers/leds/led-class.c
>> +++ b/drivers/leds/led-class.c
>> @@ -23,12 +23,6 @@
>>
>>  static struct class *leds_class;
>>
>> -static void led_update_brightness(struct led_classdev *led_cdev)
>> -{
>> -       if (led_cdev->brightness_get)
>> -               led_cdev->brightness = led_cdev->brightness_get(led_cdev);
>> -}
>> -
>>  static ssize_t brightness_show(struct device *dev,
>>                 struct device_attribute *attr, char *buf)
>>  {
>> diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
>> index 8380eb7..466ce5a 100644
>> --- a/drivers/leds/led-core.c
>> +++ b/drivers/leds/led-core.c
>> @@ -127,3 +127,19 @@ void led_set_brightness(struct led_classdev *led_cdev,
>>         __led_set_brightness(led_cdev, brightness);
>>  }
>>  EXPORT_SYMBOL(led_set_brightness);
>> +
>> +int led_update_brightness(struct led_classdev *led_cdev)
>> +{
>> +       int ret = 0;
>> +
>> +       if (led_cdev->brightness_get) {
>> +               ret = led_cdev->brightness_get(led_cdev);
>> +               if (ret >= 0) {
>> +                       led_cdev->brightness = ret;
>> +                       return 0;
>> +               }
>> +       }
>> +
>> +       return ret;
>> +}
>> +EXPORT_SYMBOL(led_update_brightness);
>> diff --git a/include/linux/leds.h b/include/linux/leds.h
>> index bc221d11..cc85b16 100644
>> --- a/include/linux/leds.h
>> +++ b/include/linux/leds.h
>> @@ -139,6 +139,16 @@ extern void led_blink_set_oneshot(struct led_classdev *led_cdev,
>>   */
>>  extern void led_set_brightness(struct led_classdev *led_cdev,
>>                                enum led_brightness brightness);
>> +/**
>> + * led_update_brightness - update LED brightness
>> + * @led_cdev: the LED to query
>> + *
>> + * Get an LED's current brightness and update led_cdev->brightness
>> + * member with the obtained value.
>> + *
>> + * Returns: 0 on success or negative error value on failure
>> + */
>> +extern int led_update_brightness(struct led_classdev *led_cdev);
>>
>>  /*
>>   * LED Triggers
>> --
>> 1.7.9.5
>>