leds: Add LED Flash class extension to the LED subsystem

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,
flash_sync_strobe and available_sync_leds. 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: Richard Purdie <rpurdie@rpsys.net>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Bryan Wu <cooloney@gmail.com>

6 files changed, 711 insertions, 0 deletions

diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index a6c3d2f153f3..25b320d64e26 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -22,6 +22,16 @@ 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
+        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 1c65a191d907..cbba921b6f1c 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 000000000000..4a19fd44f93f
--- /dev/null
+++ b/drivers/leds/led-class-flash.c
@@ -0,0 +1,486 @@
+/*
+ * LED Flash class interface
+ *
+ * Copyright (C) 2015 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/led-class-flash.h>
+#include <linux/leds.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include "leds.h"
+
+#define has_flash_op(fled_cdev, op)                             \
+        (fled_cdev && fled_cdev->ops->op)
+
+#define call_flash_op(fled_cdev, op, args...)           \
+        ((has_flash_op(fled_cdev, op)) ?                        \
+                        (fled_cdev->ops->op(fled_cdev, args)) : \
+                        -EINVAL)
+
+static const char * const led_flash_fault_names[] = {
+        "led-over-voltage",
+        "flash-timeout-exceeded",
+        "controller-over-temperature",
+        "controller-short-circuit",
+        "led-power-supply-over-current",
+        "indicator-led-fault",
+        "led-under-voltage",
+        "controller-under-voltage",
+        "led-over-temperature",
+};
+
+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 *fled_cdev = lcdev_to_flcdev(led_cdev);
+        unsigned long state;
+        ssize_t ret;
+
+        mutex_lock(&led_cdev->led_access);
+
+        if (led_sysfs_is_disabled(led_cdev)) {
+                ret = -EBUSY;
+                goto unlock;
+        }
+
+        ret = kstrtoul(buf, 10, &state);
+        if (ret)
+                goto unlock;
+
+        ret = led_set_flash_brightness(fled_cdev, state);
+        if (ret < 0)
+                goto unlock;
+
+        ret = size;
+unlock:
+        mutex_unlock(&led_cdev->led_access);
+        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 *fled_cdev = lcdev_to_flcdev(led_cdev);
+
+        /* no lock needed for this */
+        led_update_flash_brightness(fled_cdev);
+
+        return sprintf(buf, "%u\n", fled_cdev->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 *fled_cdev = lcdev_to_flcdev(led_cdev);
+
+        return sprintf(buf, "%u\n", fled_cdev->brightness.max);
+}
+static DEVICE_ATTR_RO(max_flash_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 *fled_cdev = lcdev_to_flcdev(led_cdev);
+        unsigned long state;
+        ssize_t ret = -EINVAL;
+
+        mutex_lock(&led_cdev->led_access);
+
+        if (led_sysfs_is_disabled(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(fled_cdev, state);
+        if (ret < 0)
+                goto unlock;
+        ret = size;
+unlock:
+        mutex_unlock(&led_cdev->led_access);
+        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 *fled_cdev = lcdev_to_flcdev(led_cdev);
+        bool state;
+        int ret;
+
+        /* no lock needed for this */
+        ret = led_get_flash_strobe(fled_cdev, &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 *fled_cdev = lcdev_to_flcdev(led_cdev);
+        unsigned long flash_timeout;
+        ssize_t ret;
+
+        mutex_lock(&led_cdev->led_access);
+
+        if (led_sysfs_is_disabled(led_cdev)) {
+                ret = -EBUSY;
+                goto unlock;
+        }
+
+        ret = kstrtoul(buf, 10, &flash_timeout);
+        if (ret)
+                goto unlock;
+
+        ret = led_set_flash_timeout(fled_cdev, flash_timeout);
+        if (ret < 0)
+                goto unlock;
+
+        ret = size;
+unlock:
+        mutex_unlock(&led_cdev->led_access);
+        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 *fled_cdev = lcdev_to_flcdev(led_cdev);
+
+        return sprintf(buf, "%u\n", fled_cdev->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 *fled_cdev = lcdev_to_flcdev(led_cdev);
+
+        return sprintf(buf, "%u\n", fled_cdev->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 *fled_cdev = lcdev_to_flcdev(led_cdev);
+        u32 fault, mask = 0x1;
+        char *pbuf = buf;
+        int i, ret, buf_len;
+
+        ret = led_get_flash_fault(fled_cdev, &fault);
+        if (ret < 0)
+                return -EINVAL;
+
+        *buf = '\0';
+
+        for (i = 0; i < LED_NUM_FLASH_FAULTS; ++i) {
+                if (fault & mask) {
+                        buf_len = sprintf(pbuf, "%s ",
+                                          led_flash_fault_names[i]);
+                        pbuf += buf_len;
+                }
+                mask <<= 1;
+        }
+
+        return sprintf(buf, "%s\n", buf);
+}
+static DEVICE_ATTR_RO(flash_fault);
+
+static ssize_t available_sync_leds_show(struct device *dev,
+                struct device_attribute *attr, char *buf)
+{
+        struct led_classdev *led_cdev = dev_get_drvdata(dev);
+        struct led_classdev_flash *fled_cdev = lcdev_to_flcdev(led_cdev);
+        char *pbuf = buf;
+        int i, buf_len;
+
+        buf_len = sprintf(pbuf, "[0: none] ");
+        pbuf += buf_len;
+
+        for (i = 0; i < fled_cdev->num_sync_leds; ++i) {
+                buf_len = sprintf(pbuf, "[%d: %s] ", i + 1,
+                                  fled_cdev->sync_leds[i]->led_cdev.name);
+                pbuf += buf_len;
+        }
+
+        return sprintf(buf, "%s\n", buf);
+}
+static DEVICE_ATTR_RO(available_sync_leds);
+
+static ssize_t flash_sync_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 *fled_cdev = lcdev_to_flcdev(led_cdev);
+        unsigned long led_id;
+        ssize_t ret;
+
+        mutex_lock(&led_cdev->led_access);
+
+        if (led_sysfs_is_disabled(led_cdev)) {
+                ret = -EBUSY;
+                goto unlock;
+        }
+
+        ret = kstrtoul(buf, 10, &led_id);
+        if (ret)
+                goto unlock;
+
+        if (led_id > fled_cdev->num_sync_leds) {
+                ret = -ERANGE;
+                goto unlock;
+        }
+
+        fled_cdev->sync_led_id = led_id;
+
+        ret = size;
+unlock:
+        mutex_unlock(&led_cdev->led_access);
+        return ret;
+}
+
+static ssize_t flash_sync_strobe_show(struct device *dev,
+                struct device_attribute *attr, char *buf)
+{
+        struct led_classdev *led_cdev = dev_get_drvdata(dev);
+        struct led_classdev_flash *fled_cdev = lcdev_to_flcdev(led_cdev);
+        int sled_id = fled_cdev->sync_led_id;
+        char *sync_led_name = "none";
+
+        if (fled_cdev->sync_led_id > 0)
+                sync_led_name = (char *)
+                        fled_cdev->sync_leds[sled_id - 1]->led_cdev.name;
+
+        return sprintf(buf, "[%d: %s]\n", sled_id, sync_led_name);
+}
+static DEVICE_ATTR_RW(flash_sync_strobe);
+
+static struct attribute *led_flash_strobe_attrs[] = {
+        &dev_attr_flash_strobe.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_fault_attrs[] = {
+        &dev_attr_flash_fault.attr,
+        NULL,
+};
+
+static struct attribute *led_flash_sync_strobe_attrs[] = {
+        &dev_attr_available_sync_leds.attr,
+        &dev_attr_flash_sync_strobe.attr,
+        NULL,
+};
+
+static const struct attribute_group led_flash_strobe_group = {
+        .attrs = led_flash_strobe_attrs,
+};
+
+static const struct attribute_group led_flash_timeout_group = {
+        .attrs = led_flash_timeout_attrs,
+};
+
+static const struct attribute_group led_flash_brightness_group = {
+        .attrs = led_flash_brightness_attrs,
+};
+
+static const struct attribute_group led_flash_fault_group = {
+        .attrs = led_flash_fault_attrs,
+};
+
+static const struct attribute_group led_flash_sync_strobe_group = {
+        .attrs = led_flash_sync_strobe_attrs,
+};
+
+static void led_flash_resume(struct led_classdev *led_cdev)
+{
+        struct led_classdev_flash *fled_cdev = lcdev_to_flcdev(led_cdev);
+
+        call_flash_op(fled_cdev, flash_brightness_set,
+                                        fled_cdev->brightness.val);
+        call_flash_op(fled_cdev, timeout_set, fled_cdev->timeout.val);
+}
+
+static void led_flash_init_sysfs_groups(struct led_classdev_flash *fled_cdev)
+{
+        struct led_classdev *led_cdev = &fled_cdev->led_cdev;
+        const struct led_flash_ops *ops = fled_cdev->ops;
+        const struct attribute_group **flash_groups = fled_cdev->sysfs_groups;
+
+        int num_sysfs_groups = 0;
+
+        flash_groups[num_sysfs_groups++] = &led_flash_strobe_group;
+
+        if (ops->flash_brightness_set)
+                flash_groups[num_sysfs_groups++] = &led_flash_brightness_group;
+
+        if (ops->timeout_set)
+                flash_groups[num_sysfs_groups++] = &led_flash_timeout_group;
+
+        if (ops->fault_get)
+                flash_groups[num_sysfs_groups++] = &led_flash_fault_group;
+
+        if (led_cdev->flags & LED_DEV_CAP_SYNC_STROBE)
+                flash_groups[num_sysfs_groups++] = &led_flash_sync_strobe_group;
+
+        led_cdev->groups = flash_groups;
+}
+
+int led_classdev_flash_register(struct device *parent,
+                                struct led_classdev_flash *fled_cdev)
+{
+        struct led_classdev *led_cdev;
+        const struct led_flash_ops *ops;
+        int ret;
+
+        if (!fled_cdev)
+                return -EINVAL;
+
+        led_cdev = &fled_cdev->led_cdev;
+
+        if (led_cdev->flags & LED_DEV_CAP_FLASH) {
+                if (!led_cdev->brightness_set_sync)
+                        return -EINVAL;
+
+                ops = fled_cdev->ops;
+                if (!ops || !ops->strobe_set)
+                        return -EINVAL;
+
+                led_cdev->flash_resume = led_flash_resume;
+
+                /* Select the sysfs attributes to be created for the device */
+                led_flash_init_sysfs_groups(fled_cdev);
+        }
+
+        /* Register led class device */
+        ret = led_classdev_register(parent, led_cdev);
+        if (ret < 0)
+                return ret;
+
+        /* Setting a torch brightness needs to have immediate effect */
+        led_cdev->flags &= ~SET_BRIGHTNESS_ASYNC;
+        led_cdev->flags |= SET_BRIGHTNESS_SYNC;
+
+        return 0;
+}
+EXPORT_SYMBOL_GPL(led_classdev_flash_register);
+
+void led_classdev_flash_unregister(struct led_classdev_flash *fled_cdev)
+{
+        if (!fled_cdev)
+                return;
+
+        led_classdev_unregister(&fled_cdev->led_cdev);
+}
+EXPORT_SYMBOL_GPL(led_classdev_flash_unregister);
+
+static 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 *fled_cdev, u32 timeout)
+{
+        struct led_classdev *led_cdev = &fled_cdev->led_cdev;
+        struct led_flash_setting *s = &fled_cdev->timeout;
+
+        s->val = timeout;
+        led_clamp_align(s);
+
+        if (!(led_cdev->flags & LED_SUSPENDED))
+                return call_flash_op(fled_cdev, timeout_set, s->val);
+
+        return 0;
+}
+EXPORT_SYMBOL_GPL(led_set_flash_timeout);
+
+int led_get_flash_fault(struct led_classdev_flash *fled_cdev, u32 *fault)
+{
+        return call_flash_op(fled_cdev, fault_get, fault);
+}
+EXPORT_SYMBOL_GPL(led_get_flash_fault);
+
+int led_set_flash_brightness(struct led_classdev_flash *fled_cdev,
+                                u32 brightness)
+{
+        struct led_classdev *led_cdev = &fled_cdev->led_cdev;
+        struct led_flash_setting *s = &fled_cdev->brightness;
+
+        s->val = brightness;
+        led_clamp_align(s);
+
+        if (!(led_cdev->flags & LED_SUSPENDED))
+                return call_flash_op(fled_cdev, flash_brightness_set, s->val);
+
+        return 0;
+}
+EXPORT_SYMBOL_GPL(led_set_flash_brightness);
+
+int led_update_flash_brightness(struct led_classdev_flash *fled_cdev)
+{
+        struct led_flash_setting *s = &fled_cdev->brightness;
+        u32 brightness;
+
+        if (has_flash_op(fled_cdev, flash_brightness_get)) {
+                int ret = call_flash_op(fled_cdev, flash_brightness_get,
+                                                &brightness);
+                if (ret < 0)
+                        return ret;
+
+                s->val = brightness;
+        }
+
+        return 0;
+}
+EXPORT_SYMBOL_GPL(led_update_flash_brightness);
+
+MODULE_AUTHOR("Jacek Anaszewski <j.anaszewski@samsung.com>");
+MODULE_DESCRIPTION("LED Flash class interface");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 291ca45ce8ba..795ec994c663 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -179,6 +179,10 @@ 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/include/linux/led-class-flash.h b/include/linux/led-class-flash.h
new file mode 100644
index 000000000000..5ba2facd7a51
--- /dev/null
+++ b/include/linux/led-class-flash.h
@@ -0,0 +1,207 @@
+/*
+ * LED Flash class interface
+ *
+ * Copyright (C) 2015 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>
+#include <uapi/linux/v4l2-controls.h>
+
+struct device_node;
+struct led_classdev_flash;
+
+/*
+ * Supported led fault bits - must be kept in synch
+ * with V4L2_FLASH_FAULT bits.
+ */
+#define LED_FAULT_OVER_VOLTAGE          (1 << 0)
+#define LED_FAULT_TIMEOUT               (1 << 1)
+#define LED_FAULT_OVER_TEMPERATURE      (1 << 2)
+#define LED_FAULT_SHORT_CIRCUIT         (1 << 3)
+#define LED_FAULT_OVER_CURRENT          (1 << 4)
+#define LED_FAULT_INDICATOR             (1 << 5)
+#define LED_FAULT_UNDER_VOLTAGE         (1 << 6)
+#define LED_FAULT_INPUT_VOLTAGE         (1 << 7)
+#define LED_FAULT_LED_OVER_TEMPERATURE  (1 << 8)
+#define LED_NUM_FLASH_FAULTS            9
+
+#define LED_FLASH_MAX_SYSFS_GROUPS 7
+
+struct led_flash_ops {
+        /* set flash brightness */
+        int (*flash_brightness_set)(struct led_classdev_flash *fled_cdev,
+                                        u32 brightness);
+        /* get flash brightness */
+        int (*flash_brightness_get)(struct led_classdev_flash *fled_cdev,
+                                        u32 *brightness);
+        /* set flash strobe state */
+        int (*strobe_set)(struct led_classdev_flash *fled_cdev, bool state);
+        /* get flash strobe state */
+        int (*strobe_get)(struct led_classdev_flash *fled_cdev, bool *state);
+        /* set flash timeout */
+        int (*timeout_set)(struct led_classdev_flash *fled_cdev, u32 timeout);
+        /* get the flash LED fault */
+        int (*fault_get)(struct led_classdev_flash *fled_cdev, 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;
+};
+
+struct led_classdev_flash {
+        /* led class device */
+        struct led_classdev led_cdev;
+
+        /* flash led specific ops */
+        const struct led_flash_ops *ops;
+
+        /* flash brightness value in microamperes along with its constraints */
+        struct led_flash_setting brightness;
+
+        /* flash timeout value in microseconds along with its constraints */
+        struct led_flash_setting timeout;
+
+        /* LED Flash class sysfs groups */
+        const struct attribute_group *sysfs_groups[LED_FLASH_MAX_SYSFS_GROUPS];
+
+        /* LEDs available for flash strobe synchronization */
+        struct led_classdev_flash **sync_leds;
+
+        /* Number of LEDs available for flash strobe synchronization */
+        int num_sync_leds;
+
+        /*
+         * The identifier of the sub-led to synchronize the flash strobe with.
+         * Identifiers start from 1, which reflects the first element from the
+         * sync_leds array. 0 means that the flash strobe should not be
+         * synchronized.
+         */
+        u32 sync_led_id;
+};
+
+static inline struct led_classdev_flash *lcdev_to_flcdev(
+                                                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
+ * @fled_cdev: the led_classdev_flash structure for this device
+ *
+ * Returns: 0 on success or negative error value on failure
+ */
+extern int led_classdev_flash_register(struct device *parent,
+                                struct led_classdev_flash *fled_cdev);
+
+/**
+ * led_classdev_flash_unregister - unregisters an object of led_classdev class
+ *                                 with support for flash LEDs
+ * @fled_cdev: the flash LED to unregister
+ *
+ * Unregister a previously registered via led_classdev_flash_register object
+ */
+extern void led_classdev_flash_unregister(struct led_classdev_flash *fled_cdev);
+
+/**
+ * led_set_flash_strobe - setup flash strobe
+ * @fled_cdev: the flash LED to set strobe on
+ * @state: 1 - strobe flash, 0 - stop flash strobe
+ *
+ * Strobe the flash LED.
+ *
+ * Returns: 0 on success or negative error value on failure
+ */
+static inline int led_set_flash_strobe(struct led_classdev_flash *fled_cdev,
+                                        bool state)
+{
+        return fled_cdev->ops->strobe_set(fled_cdev, state);
+}
+
+/**
+ * led_get_flash_strobe - get flash strobe status
+ * @fled_cdev: the flash LED to query
+ * @state: 1 - flash is strobing, 0 - flash is off
+ *
+ * Check whether the flash is strobing at the moment.
+ *
+ * Returns: 0 on success or negative error value on failure
+ */
+static inline int led_get_flash_strobe(struct led_classdev_flash *fled_cdev,
+                                        bool *state)
+{
+        if (fled_cdev->ops->strobe_get)
+                return fled_cdev->ops->strobe_get(fled_cdev, state);
+
+        return -EINVAL;
+}
+
+/**
+ * led_set_flash_brightness - set flash LED brightness
+ * @fled_cdev: the flash LED to set
+ * @brightness: the brightness to set it to
+ *
+ * Set a flash LED's brightness.
+ *
+ * Returns: 0 on success or negative error value on failure
+ */
+extern int led_set_flash_brightness(struct led_classdev_flash *fled_cdev,
+                                        u32 brightness);
+
+/**
+ * led_update_flash_brightness - update flash LED brightness
+ * @fled_cdev: 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 *fled_cdev);
+
+/**
+ * led_set_flash_timeout - set flash LED timeout
+ * @fled_cdev: the flash LED to set
+ * @timeout: the flash timeout to set it to
+ *
+ * Set the flash strobe duration.
+ *
+ * Returns: 0 on success or negative error value on failure
+ */
+extern int led_set_flash_timeout(struct led_classdev_flash *fled_cdev,
+                                        u32 timeout);
+
+/**
+ * led_get_flash_fault - get the flash LED fault
+ * @fled_cdev: 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 *fled_cdev,
+                                        u32 *fault);
+
+#endif  /* __LINUX_FLASH_LEDS_H_INCLUDED */
diff --git a/include/linux/leds.h b/include/linux/leds.h
index cfceef32c9b3..f70f84f35674 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -46,6 +46,8 @@ struct led_classdev {
 #define LED_SYSFS_DISABLE       (1 << 20)
 #define SET_BRIGHTNESS_ASYNC    (1 << 21)
 #define SET_BRIGHTNESS_SYNC     (1 << 22)
+#define LED_DEV_CAP_FLASH       (1 << 23)
+#define LED_DEV_CAP_SYNC_STROBE (1 << 24)
 
         /* Set LED brightness level */
         /* Must not sleep, use a workqueue if needed */
@@ -81,6 +83,7 @@ struct led_classdev {
         unsigned long            blink_delay_on, blink_delay_off;
         struct timer_list        blink_timer;
         int                      blink_brightness;
+        void                    (*flash_resume)(struct led_classdev *led_cdev);
 
         struct work_struct      set_brightness_work;
         int                     delayed_set_value;