media: Add registration helpers for V4L2 flash sub-devices

This patch adds helper functions for registering/unregistering
LED Flash class devices as V4L2 sub-devices. The functions should
be called from the LED subsystem device driver. In case the
support for V4L2 Flash sub-devices is disabled in the kernel
config the functions' empty versions will be used.

Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Sakari Ailus <sakari.ailus@iki.fi>
Cc: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Bryan Wu <cooloney@gmail.com>

4 files changed, 871 insertions, 0 deletions

diff --git a/drivers/media/v4l2-core/Kconfig b/drivers/media/v4l2-core/Kconfig
index ba7e21a73023..c505dc33e4db 100644
--- a/drivers/media/v4l2-core/Kconfig
+++ b/drivers/media/v4l2-core/Kconfig
@@ -44,6 +44,17 @@ config V4L2_MEM2MEM_DEV
         tristate
         depends on VIDEOBUF2_CORE
 
+# Used by LED subsystem flash drivers
+config V4L2_FLASH_LED_CLASS
+        tristate "V4L2 flash API for LED flash class devices"
+        depends on VIDEO_V4L2_SUBDEV_API
+        depends on LEDS_CLASS_FLASH
+        ---help---
+          Say Y here to enable V4L2 flash API support for LED flash
+          class drivers.
+
+          When in doubt, say N.
+
 # Used by drivers that need Videobuf modules
 config VIDEOBUF_GEN
         tristate
diff --git a/drivers/media/v4l2-core/Makefile b/drivers/media/v4l2-core/Makefile
index 63d29f27538c..dc3de00d68b5 100644
--- a/drivers/media/v4l2-core/Makefile
+++ b/drivers/media/v4l2-core/Makefile
@@ -22,6 +22,8 @@ obj-$(CONFIG_VIDEO_TUNER) += tuner.o
 
 obj-$(CONFIG_V4L2_MEM2MEM_DEV) += v4l2-mem2mem.o
 
+obj-$(CONFIG_V4L2_FLASH_LED_CLASS) += v4l2-flash-led-class.o
+
 obj-$(CONFIG_VIDEOBUF_GEN) += videobuf-core.o
 obj-$(CONFIG_VIDEOBUF_DMA_SG) += videobuf-dma-sg.o
 obj-$(CONFIG_VIDEOBUF_DMA_CONTIG) += videobuf-dma-contig.o
diff --git a/drivers/media/v4l2-core/v4l2-flash-led-class.c b/drivers/media/v4l2-core/v4l2-flash-led-class.c
new file mode 100644
index 000000000000..5bdfb8d5263a
--- /dev/null
+++ b/drivers/media/v4l2-core/v4l2-flash-led-class.c
@@ -0,0 +1,710 @@
+/*
+ * V4L2 flash LED sub-device registration helpers.
+ *
+ *      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/led-class-flash.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <media/v4l2-flash-led-class.h>
+
+#define has_flash_op(v4l2_flash, op)                            \
+        (v4l2_flash && v4l2_flash->ops->op)
+
+#define call_flash_op(v4l2_flash, op, arg)                      \
+                (has_flash_op(v4l2_flash, op) ?                 \
+                        v4l2_flash->ops->op(v4l2_flash, arg) :  \
+                        -EINVAL)
+
+enum ctrl_init_data_id {
+        LED_MODE,
+        TORCH_INTENSITY,
+        FLASH_INTENSITY,
+        INDICATOR_INTENSITY,
+        FLASH_TIMEOUT,
+        STROBE_SOURCE,
+        /*
+         * Only above values are applicable to
+         * the 'ctrls' array in the struct v4l2_flash.
+         */
+        FLASH_STROBE,
+        STROBE_STOP,
+        STROBE_STATUS,
+        FLASH_FAULT,
+        NUM_FLASH_CTRLS,
+};
+
+static enum led_brightness __intensity_to_led_brightness(
+                                        struct v4l2_ctrl *ctrl, s32 intensity)
+{
+        intensity -= ctrl->minimum;
+        intensity /= (u32) ctrl->step;
+
+        /*
+         * Indicator LEDs, unlike torch LEDs, are turned on/off basing on
+         * the state of V4L2_CID_FLASH_INDICATOR_INTENSITY control only.
+         * Therefore it must be possible to set it to 0 level which in
+         * the LED subsystem reflects LED_OFF state.
+         */
+        if (ctrl->minimum)
+                ++intensity;
+
+        return intensity;
+}
+
+static s32 __led_brightness_to_intensity(struct v4l2_ctrl *ctrl,
+                                         enum led_brightness brightness)
+{
+        /*
+         * Indicator LEDs, unlike torch LEDs, are turned on/off basing on
+         * the state of V4L2_CID_FLASH_INDICATOR_INTENSITY control only.
+         * Do not decrement brightness read from the LED subsystem for
+         * indicator LED as it may equal 0. For torch LEDs this function
+         * is called only when V4L2_FLASH_LED_MODE_TORCH is set and the
+         * brightness read is guaranteed to be greater than 0. In the mode
+         * V4L2_FLASH_LED_MODE_NONE the cached torch intensity value is used.
+         */
+        if (ctrl->id != V4L2_CID_FLASH_INDICATOR_INTENSITY)
+                --brightness;
+
+        return (brightness * ctrl->step) + ctrl->minimum;
+}
+
+static void v4l2_flash_set_led_brightness(struct v4l2_flash *v4l2_flash,
+                                        struct v4l2_ctrl *ctrl)
+{
+        struct v4l2_ctrl **ctrls = v4l2_flash->ctrls;
+        enum led_brightness brightness;
+
+        if (has_flash_op(v4l2_flash, intensity_to_led_brightness))
+                brightness = call_flash_op(v4l2_flash,
+                                        intensity_to_led_brightness,
+                                        ctrl->val);
+        else
+                brightness = __intensity_to_led_brightness(ctrl, ctrl->val);
+        /*
+         * In case a LED Flash class driver provides ops for custom
+         * brightness <-> intensity conversion, it also must have defined
+         * related v4l2 control step == 1. In such a case a backward conversion
+         * from led brightness to v4l2 intensity is required to find out the
+         * the aligned intensity value.
+         */
+        if (has_flash_op(v4l2_flash, led_brightness_to_intensity))
+                ctrl->val = call_flash_op(v4l2_flash,
+                                        led_brightness_to_intensity,
+                                        brightness);
+
+        if (ctrl == ctrls[TORCH_INTENSITY]) {
+                if (ctrls[LED_MODE]->val != V4L2_FLASH_LED_MODE_TORCH)
+                        return;
+
+                led_set_brightness(&v4l2_flash->fled_cdev->led_cdev,
+                                        brightness);
+        } else {
+                led_set_brightness(&v4l2_flash->iled_cdev->led_cdev,
+                                        brightness);
+        }
+}
+
+static int v4l2_flash_update_led_brightness(struct v4l2_flash *v4l2_flash,
+                                        struct v4l2_ctrl *ctrl)
+{
+        struct v4l2_ctrl **ctrls = v4l2_flash->ctrls;
+        struct led_classdev *led_cdev;
+        int ret;
+
+        if (ctrl == ctrls[TORCH_INTENSITY]) {
+                /*
+                 * Update torch brightness only if in TORCH_MODE. In other modes
+                 * torch led is turned off, which would spuriously inform the
+                 * user space that V4L2_CID_FLASH_TORCH_INTENSITY control value
+                 * has changed to 0.
+                 */
+                if (ctrls[LED_MODE]->val != V4L2_FLASH_LED_MODE_TORCH)
+                        return 0;
+                led_cdev = &v4l2_flash->fled_cdev->led_cdev;
+        } else {
+                led_cdev = &v4l2_flash->iled_cdev->led_cdev;
+        }
+
+        ret = led_update_brightness(led_cdev);
+        if (ret < 0)
+                return ret;
+
+        if (has_flash_op(v4l2_flash, led_brightness_to_intensity))
+                ctrl->val = call_flash_op(v4l2_flash,
+                                                led_brightness_to_intensity,
+                                                led_cdev->brightness);
+        else
+                ctrl->val = __led_brightness_to_intensity(ctrl,
+                                                led_cdev->brightness);
+
+        return 0;
+}
+
+static int v4l2_flash_g_volatile_ctrl(struct v4l2_ctrl *c)
+{
+        struct v4l2_flash *v4l2_flash = v4l2_ctrl_to_v4l2_flash(c);
+        struct led_classdev_flash *fled_cdev = v4l2_flash->fled_cdev;
+        bool is_strobing;
+        int ret;
+
+        switch (c->id) {
+        case V4L2_CID_FLASH_TORCH_INTENSITY:
+        case V4L2_CID_FLASH_INDICATOR_INTENSITY:
+                return v4l2_flash_update_led_brightness(v4l2_flash, c);
+        case V4L2_CID_FLASH_INTENSITY:
+                ret = led_update_flash_brightness(fled_cdev);
+                if (ret < 0)
+                        return ret;
+                /*
+                 * No conversion is needed as LED Flash class also uses
+                 * microamperes for flash intensity units.
+                 */
+                c->val = fled_cdev->brightness.val;
+                return 0;
+        case V4L2_CID_FLASH_STROBE_STATUS:
+                ret = led_get_flash_strobe(fled_cdev, &is_strobing);
+                if (ret < 0)
+                        return ret;
+                c->val = is_strobing;
+                return 0;
+        case V4L2_CID_FLASH_FAULT:
+                /* LED faults map directly to V4L2 flash faults */
+                return led_get_flash_fault(fled_cdev, &c->val);
+        default:
+                return -EINVAL;
+        }
+}
+
+static bool __software_strobe_mode_inactive(struct v4l2_ctrl **ctrls)
+{
+        return ((ctrls[LED_MODE]->val != V4L2_FLASH_LED_MODE_FLASH) ||
+                (ctrls[STROBE_SOURCE] && (ctrls[STROBE_SOURCE]->val !=
+                                V4L2_FLASH_STROBE_SOURCE_SOFTWARE)));
+}
+
+static int v4l2_flash_s_ctrl(struct v4l2_ctrl *c)
+{
+        struct v4l2_flash *v4l2_flash = v4l2_ctrl_to_v4l2_flash(c);
+        struct led_classdev_flash *fled_cdev = v4l2_flash->fled_cdev;
+        struct led_classdev *led_cdev = &fled_cdev->led_cdev;
+        struct v4l2_ctrl **ctrls = v4l2_flash->ctrls;
+        bool external_strobe;
+        int ret = 0;
+
+        switch (c->id) {
+        case V4L2_CID_FLASH_LED_MODE:
+                switch (c->val) {
+                case V4L2_FLASH_LED_MODE_NONE:
+                        led_set_brightness(led_cdev, LED_OFF);
+                        return led_set_flash_strobe(fled_cdev, false);
+                case V4L2_FLASH_LED_MODE_FLASH:
+                        /* Turn the torch LED off */
+                        led_set_brightness(led_cdev, LED_OFF);
+                        if (ctrls[STROBE_SOURCE]) {
+                                external_strobe = (ctrls[STROBE_SOURCE]->val ==
+                                        V4L2_FLASH_STROBE_SOURCE_EXTERNAL);
+
+                                ret = call_flash_op(v4l2_flash,
+                                                external_strobe_set,
+                                                external_strobe);
+                        }
+                        return ret;
+                case V4L2_FLASH_LED_MODE_TORCH:
+                        if (ctrls[STROBE_SOURCE]) {
+                                ret = call_flash_op(v4l2_flash,
+                                                external_strobe_set,
+                                                false);
+                                if (ret < 0)
+                                        return ret;
+                        }
+                        /* Stop flash strobing */
+                        ret = led_set_flash_strobe(fled_cdev, false);
+                        if (ret < 0)
+                                return ret;
+
+                        v4l2_flash_set_led_brightness(v4l2_flash,
+                                                        ctrls[TORCH_INTENSITY]);
+                        return 0;
+                }
+                break;
+        case V4L2_CID_FLASH_STROBE_SOURCE:
+                external_strobe = (c->val == V4L2_FLASH_STROBE_SOURCE_EXTERNAL);
+                /*
+                 * For some hardware arrangements setting strobe source may
+                 * affect torch mode. Therefore, if not in the flash mode,
+                 * cache only this setting. It will be applied upon switching
+                 * to flash mode.
+                 */
+                if (ctrls[LED_MODE]->val != V4L2_FLASH_LED_MODE_FLASH)
+                        return 0;
+
+                return call_flash_op(v4l2_flash, external_strobe_set,
+                                        external_strobe);
+        case V4L2_CID_FLASH_STROBE:
+                if (__software_strobe_mode_inactive(ctrls))
+                        return -EBUSY;
+                return led_set_flash_strobe(fled_cdev, true);
+        case V4L2_CID_FLASH_STROBE_STOP:
+                if (__software_strobe_mode_inactive(ctrls))
+                        return -EBUSY;
+                return led_set_flash_strobe(fled_cdev, false);
+        case V4L2_CID_FLASH_TIMEOUT:
+                /*
+                 * No conversion is needed as LED Flash class also uses
+                 * microseconds for flash timeout units.
+                 */
+                return led_set_flash_timeout(fled_cdev, c->val);
+        case V4L2_CID_FLASH_INTENSITY:
+                /*
+                 * No conversion is needed as LED Flash class also uses
+                 * microamperes for flash intensity units.
+                 */
+                return led_set_flash_brightness(fled_cdev, c->val);
+        case V4L2_CID_FLASH_TORCH_INTENSITY:
+        case V4L2_CID_FLASH_INDICATOR_INTENSITY:
+                v4l2_flash_set_led_brightness(v4l2_flash, c);
+                return 0;
+        }
+
+        return -EINVAL;
+}
+
+static const struct v4l2_ctrl_ops v4l2_flash_ctrl_ops = {
+        .g_volatile_ctrl = v4l2_flash_g_volatile_ctrl,
+        .s_ctrl = v4l2_flash_s_ctrl,
+};
+
+static void __lfs_to_v4l2_ctrl_config(struct led_flash_setting *s,
+                                struct v4l2_ctrl_config *c)
+{
+        c->min = s->min;
+        c->max = s->max;
+        c->step = s->step;
+        c->def = s->val;
+}
+
+static void __fill_ctrl_init_data(struct v4l2_flash *v4l2_flash,
+                          struct v4l2_flash_config *flash_cfg,
+                          struct v4l2_flash_ctrl_data *ctrl_init_data)
+{
+        struct led_classdev_flash *fled_cdev = v4l2_flash->fled_cdev;
+        const struct led_flash_ops *fled_cdev_ops = fled_cdev->ops;
+        struct led_classdev *led_cdev = &fled_cdev->led_cdev;
+        struct v4l2_ctrl_config *ctrl_cfg;
+        u32 mask;
+
+        /* Init FLASH_FAULT ctrl data */
+        if (flash_cfg->flash_faults) {
+                ctrl_init_data[FLASH_FAULT].cid = V4L2_CID_FLASH_FAULT;
+                ctrl_cfg = &ctrl_init_data[FLASH_FAULT].config;
+                ctrl_cfg->id = V4L2_CID_FLASH_FAULT;
+                ctrl_cfg->max = flash_cfg->flash_faults;
+                ctrl_cfg->flags = V4L2_CTRL_FLAG_VOLATILE |
+                                  V4L2_CTRL_FLAG_READ_ONLY;
+        }
+
+        /* Init FLASH_LED_MODE ctrl data */
+        mask = 1 << V4L2_FLASH_LED_MODE_NONE |
+               1 << V4L2_FLASH_LED_MODE_TORCH;
+        if (led_cdev->flags & LED_DEV_CAP_FLASH)
+                mask |= 1 << V4L2_FLASH_LED_MODE_FLASH;
+
+        ctrl_init_data[LED_MODE].cid = V4L2_CID_FLASH_LED_MODE;
+        ctrl_cfg = &ctrl_init_data[LED_MODE].config;
+        ctrl_cfg->id = V4L2_CID_FLASH_LED_MODE;
+        ctrl_cfg->max = V4L2_FLASH_LED_MODE_TORCH;
+        ctrl_cfg->menu_skip_mask = ~mask;
+        ctrl_cfg->def = V4L2_FLASH_LED_MODE_NONE;
+        ctrl_cfg->flags = 0;
+
+        /* Init TORCH_INTENSITY ctrl data */
+        ctrl_init_data[TORCH_INTENSITY].cid = V4L2_CID_FLASH_TORCH_INTENSITY;
+        ctrl_cfg = &ctrl_init_data[TORCH_INTENSITY].config;
+        __lfs_to_v4l2_ctrl_config(&flash_cfg->torch_intensity, ctrl_cfg);
+        ctrl_cfg->id = V4L2_CID_FLASH_TORCH_INTENSITY;
+        ctrl_cfg->flags = V4L2_CTRL_FLAG_VOLATILE |
+                          V4L2_CTRL_FLAG_EXECUTE_ON_WRITE;
+
+        /* Init INDICATOR_INTENSITY ctrl data */
+        if (v4l2_flash->iled_cdev) {
+                ctrl_init_data[INDICATOR_INTENSITY].cid =
+                                        V4L2_CID_FLASH_INDICATOR_INTENSITY;
+                ctrl_cfg = &ctrl_init_data[INDICATOR_INTENSITY].config;
+                __lfs_to_v4l2_ctrl_config(&flash_cfg->indicator_intensity,
+                                          ctrl_cfg);
+                ctrl_cfg->id = V4L2_CID_FLASH_INDICATOR_INTENSITY;
+                ctrl_cfg->min = 0;
+                ctrl_cfg->flags = V4L2_CTRL_FLAG_VOLATILE |
+                                  V4L2_CTRL_FLAG_EXECUTE_ON_WRITE;
+        }
+
+        if (!(led_cdev->flags & LED_DEV_CAP_FLASH))
+                return;
+
+        /* Init FLASH_STROBE ctrl data */
+        ctrl_init_data[FLASH_STROBE].cid = V4L2_CID_FLASH_STROBE;
+        ctrl_cfg = &ctrl_init_data[FLASH_STROBE].config;
+        ctrl_cfg->id = V4L2_CID_FLASH_STROBE;
+
+        /* Init STROBE_STOP ctrl data */
+        ctrl_init_data[STROBE_STOP].cid = V4L2_CID_FLASH_STROBE_STOP;
+        ctrl_cfg = &ctrl_init_data[STROBE_STOP].config;
+        ctrl_cfg->id = V4L2_CID_FLASH_STROBE_STOP;
+
+        /* Init FLASH_STROBE_SOURCE ctrl data */
+        if (flash_cfg->has_external_strobe) {
+                mask = (1 << V4L2_FLASH_STROBE_SOURCE_SOFTWARE) |
+                       (1 << V4L2_FLASH_STROBE_SOURCE_EXTERNAL);
+                ctrl_init_data[STROBE_SOURCE].cid =
+                                        V4L2_CID_FLASH_STROBE_SOURCE;
+                ctrl_cfg = &ctrl_init_data[STROBE_SOURCE].config;
+                ctrl_cfg->id = V4L2_CID_FLASH_STROBE_SOURCE;
+                ctrl_cfg->max = V4L2_FLASH_STROBE_SOURCE_EXTERNAL;
+                ctrl_cfg->menu_skip_mask = ~mask;
+                ctrl_cfg->def = V4L2_FLASH_STROBE_SOURCE_SOFTWARE;
+        }
+
+        /* Init STROBE_STATUS ctrl data */
+        if (fled_cdev_ops->strobe_get) {
+                ctrl_init_data[STROBE_STATUS].cid =
+                                        V4L2_CID_FLASH_STROBE_STATUS;
+                ctrl_cfg = &ctrl_init_data[STROBE_STATUS].config;
+                ctrl_cfg->id = V4L2_CID_FLASH_STROBE_STATUS;
+                ctrl_cfg->flags = V4L2_CTRL_FLAG_VOLATILE |
+                                  V4L2_CTRL_FLAG_READ_ONLY;
+        }
+
+        /* Init FLASH_TIMEOUT ctrl data */
+        if (fled_cdev_ops->timeout_set) {
+                ctrl_init_data[FLASH_TIMEOUT].cid = V4L2_CID_FLASH_TIMEOUT;
+                ctrl_cfg = &ctrl_init_data[FLASH_TIMEOUT].config;
+                __lfs_to_v4l2_ctrl_config(&fled_cdev->timeout, ctrl_cfg);
+                ctrl_cfg->id = V4L2_CID_FLASH_TIMEOUT;
+        }
+
+        /* Init FLASH_INTENSITY ctrl data */
+        if (fled_cdev_ops->flash_brightness_set) {
+                ctrl_init_data[FLASH_INTENSITY].cid = V4L2_CID_FLASH_INTENSITY;
+                ctrl_cfg = &ctrl_init_data[FLASH_INTENSITY].config;
+                __lfs_to_v4l2_ctrl_config(&fled_cdev->brightness, ctrl_cfg);
+                ctrl_cfg->id = V4L2_CID_FLASH_INTENSITY;
+                ctrl_cfg->flags = V4L2_CTRL_FLAG_VOLATILE |
+                                  V4L2_CTRL_FLAG_EXECUTE_ON_WRITE;
+        }
+}
+
+static int v4l2_flash_init_controls(struct v4l2_flash *v4l2_flash,
+                                struct v4l2_flash_config *flash_cfg)
+
+{
+        struct v4l2_flash_ctrl_data *ctrl_init_data;
+        struct v4l2_ctrl *ctrl;
+        struct v4l2_ctrl_config *ctrl_cfg;
+        int i, ret, num_ctrls = 0;
+
+        v4l2_flash->ctrls = devm_kzalloc(v4l2_flash->sd.dev,
+                                        sizeof(*v4l2_flash->ctrls) *
+                                        (STROBE_SOURCE + 1), GFP_KERNEL);
+        if (!v4l2_flash->ctrls)
+                return -ENOMEM;
+
+        /* allocate memory dynamically so as not to exceed stack frame size */
+        ctrl_init_data = kcalloc(NUM_FLASH_CTRLS, sizeof(*ctrl_init_data),
+                                        GFP_KERNEL);
+        if (!ctrl_init_data)
+                return -ENOMEM;
+
+        __fill_ctrl_init_data(v4l2_flash, flash_cfg, ctrl_init_data);
+
+        for (i = 0; i < NUM_FLASH_CTRLS; ++i)
+                if (ctrl_init_data[i].cid)
+                        ++num_ctrls;
+
+        v4l2_ctrl_handler_init(&v4l2_flash->hdl, num_ctrls);
+
+        for (i = 0; i < NUM_FLASH_CTRLS; ++i) {
+                ctrl_cfg = &ctrl_init_data[i].config;
+                if (!ctrl_init_data[i].cid)
+                        continue;
+
+                if (ctrl_cfg->id == V4L2_CID_FLASH_LED_MODE ||
+                    ctrl_cfg->id == V4L2_CID_FLASH_STROBE_SOURCE)
+                        ctrl = v4l2_ctrl_new_std_menu(&v4l2_flash->hdl,
+                                                &v4l2_flash_ctrl_ops,
+                                                ctrl_cfg->id,
+                                                ctrl_cfg->max,
+                                                ctrl_cfg->menu_skip_mask,
+                                                ctrl_cfg->def);
+                else
+                        ctrl = v4l2_ctrl_new_std(&v4l2_flash->hdl,
+                                                &v4l2_flash_ctrl_ops,
+                                                ctrl_cfg->id,
+                                                ctrl_cfg->min,
+                                                ctrl_cfg->max,
+                                                ctrl_cfg->step,
+                                                ctrl_cfg->def);
+
+                if (ctrl)
+                        ctrl->flags |= ctrl_cfg->flags;
+
+                if (i <= STROBE_SOURCE)
+                        v4l2_flash->ctrls[i] = ctrl;
+        }
+
+        kfree(ctrl_init_data);
+
+        if (v4l2_flash->hdl.error) {
+                ret = v4l2_flash->hdl.error;
+                goto error_free_handler;
+        }
+
+        v4l2_ctrl_handler_setup(&v4l2_flash->hdl);
+
+        v4l2_flash->sd.ctrl_handler = &v4l2_flash->hdl;
+
+        return 0;
+
+error_free_handler:
+        v4l2_ctrl_handler_free(&v4l2_flash->hdl);
+        return ret;
+}
+
+static int __sync_device_with_v4l2_controls(struct v4l2_flash *v4l2_flash)
+{
+        struct led_classdev_flash *fled_cdev = v4l2_flash->fled_cdev;
+        struct v4l2_ctrl **ctrls = v4l2_flash->ctrls;
+        int ret = 0;
+
+        v4l2_flash_set_led_brightness(v4l2_flash, ctrls[TORCH_INTENSITY]);
+
+        if (ctrls[INDICATOR_INTENSITY])
+                v4l2_flash_set_led_brightness(v4l2_flash,
+                                                ctrls[INDICATOR_INTENSITY]);
+
+        if (ctrls[FLASH_TIMEOUT]) {
+                ret = led_set_flash_timeout(fled_cdev,
+                                        ctrls[FLASH_TIMEOUT]->val);
+                if (ret < 0)
+                        return ret;
+        }
+
+        if (ctrls[FLASH_INTENSITY]) {
+                ret = led_set_flash_brightness(fled_cdev,
+                                        ctrls[FLASH_INTENSITY]->val);
+                if (ret < 0)
+                        return ret;
+        }
+
+        /*
+         * For some hardware arrangements setting strobe source may affect
+         * torch mode. Synchronize strobe source setting only if not in torch
+         * mode. For torch mode case it will get synchronized upon switching
+         * to flash mode.
+         */
+        if (ctrls[STROBE_SOURCE] &&
+            ctrls[LED_MODE]->val != V4L2_FLASH_LED_MODE_TORCH)
+                ret = call_flash_op(v4l2_flash, external_strobe_set,
+                                        ctrls[STROBE_SOURCE]->val);
+
+        return ret;
+}
+
+/*
+ * V4L2 subdev internal operations
+ */
+
+static int v4l2_flash_open(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh)
+{
+        struct v4l2_flash *v4l2_flash = v4l2_subdev_to_v4l2_flash(sd);
+        struct led_classdev_flash *fled_cdev = v4l2_flash->fled_cdev;
+        struct led_classdev *led_cdev = &fled_cdev->led_cdev;
+        struct led_classdev_flash *iled_cdev = v4l2_flash->iled_cdev;
+        struct led_classdev *led_cdev_ind = NULL;
+        int ret = 0;
+
+        if (!v4l2_fh_is_singular(&fh->vfh))
+                return 0;
+
+        mutex_lock(&led_cdev->led_access);
+
+        led_sysfs_disable(led_cdev);
+        led_trigger_remove(led_cdev);
+
+        mutex_unlock(&led_cdev->led_access);
+
+        if (iled_cdev) {
+                led_cdev_ind = &iled_cdev->led_cdev;
+
+                mutex_lock(&led_cdev_ind->led_access);
+
+                led_sysfs_disable(led_cdev_ind);
+                led_trigger_remove(led_cdev_ind);
+
+                mutex_unlock(&led_cdev_ind->led_access);
+        }
+
+        ret = __sync_device_with_v4l2_controls(v4l2_flash);
+        if (ret < 0)
+                goto out_sync_device;
+
+        return 0;
+out_sync_device:
+        mutex_lock(&led_cdev->led_access);
+        led_sysfs_enable(led_cdev);
+        mutex_unlock(&led_cdev->led_access);
+
+        if (led_cdev_ind) {
+                mutex_lock(&led_cdev_ind->led_access);
+                led_sysfs_enable(led_cdev_ind);
+                mutex_unlock(&led_cdev_ind->led_access);
+        }
+
+        return ret;
+}
+
+static int v4l2_flash_close(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh)
+{
+        struct v4l2_flash *v4l2_flash = v4l2_subdev_to_v4l2_flash(sd);
+        struct led_classdev_flash *fled_cdev = v4l2_flash->fled_cdev;
+        struct led_classdev *led_cdev = &fled_cdev->led_cdev;
+        struct led_classdev_flash *iled_cdev = v4l2_flash->iled_cdev;
+        int ret = 0;
+
+        if (!v4l2_fh_is_singular(&fh->vfh))
+                return 0;
+
+        mutex_lock(&led_cdev->led_access);
+
+        if (v4l2_flash->ctrls[STROBE_SOURCE])
+                ret = v4l2_ctrl_s_ctrl(v4l2_flash->ctrls[STROBE_SOURCE],
+                                V4L2_FLASH_STROBE_SOURCE_SOFTWARE);
+        led_sysfs_enable(led_cdev);
+
+        mutex_unlock(&led_cdev->led_access);
+
+        if (iled_cdev) {
+                struct led_classdev *led_cdev_ind = &iled_cdev->led_cdev;
+
+                mutex_lock(&led_cdev_ind->led_access);
+                led_sysfs_enable(led_cdev_ind);
+                mutex_unlock(&led_cdev_ind->led_access);
+        }
+
+        return ret;
+}
+
+static const struct v4l2_subdev_internal_ops v4l2_flash_subdev_internal_ops = {
+        .open = v4l2_flash_open,
+        .close = v4l2_flash_close,
+};
+
+static const struct v4l2_subdev_core_ops v4l2_flash_core_ops = {
+        .queryctrl = v4l2_subdev_queryctrl,
+        .querymenu = v4l2_subdev_querymenu,
+};
+
+static const struct v4l2_subdev_ops v4l2_flash_subdev_ops = {
+        .core = &v4l2_flash_core_ops,
+};
+
+struct v4l2_flash *v4l2_flash_init(
+        struct device *dev, struct device_node *of_node,
+        struct led_classdev_flash *fled_cdev,
+        struct led_classdev_flash *iled_cdev,
+        const struct v4l2_flash_ops *ops,
+        struct v4l2_flash_config *config)
+{
+        struct v4l2_flash *v4l2_flash;
+        struct led_classdev *led_cdev;
+        struct v4l2_subdev *sd;
+        int ret;
+
+        if (!fled_cdev || !ops || !config)
+                return ERR_PTR(-EINVAL);
+
+        led_cdev = &fled_cdev->led_cdev;
+
+        v4l2_flash = devm_kzalloc(led_cdev->dev, sizeof(*v4l2_flash),
+                                        GFP_KERNEL);
+        if (!v4l2_flash)
+                return ERR_PTR(-ENOMEM);
+
+        sd = &v4l2_flash->sd;
+        v4l2_flash->fled_cdev = fled_cdev;
+        v4l2_flash->iled_cdev = iled_cdev;
+        v4l2_flash->ops = ops;
+        sd->dev = dev;
+        sd->of_node = of_node;
+        v4l2_subdev_init(sd, &v4l2_flash_subdev_ops);
+        sd->internal_ops = &v4l2_flash_subdev_internal_ops;
+        sd->flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
+        strlcpy(sd->name, config->dev_name, sizeof(sd->name));
+
+        ret = media_entity_init(&sd->entity, 0, NULL, 0);
+        if (ret < 0)
+                return ERR_PTR(ret);
+
+        sd->entity.type = MEDIA_ENT_T_V4L2_SUBDEV_FLASH;
+
+        ret = v4l2_flash_init_controls(v4l2_flash, config);
+        if (ret < 0)
+                goto err_init_controls;
+
+        if (sd->of_node)
+                of_node_get(sd->of_node);
+        else
+                of_node_get(led_cdev->dev->of_node);
+
+        ret = v4l2_async_register_subdev(sd);
+        if (ret < 0)
+                goto err_async_register_sd;
+
+        return v4l2_flash;
+
+err_async_register_sd:
+        of_node_put(led_cdev->dev->of_node);
+        v4l2_ctrl_handler_free(sd->ctrl_handler);
+err_init_controls:
+        media_entity_cleanup(&sd->entity);
+
+        return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_GPL(v4l2_flash_init);
+
+void v4l2_flash_release(struct v4l2_flash *v4l2_flash)
+{
+        struct v4l2_subdev *sd;
+        struct led_classdev *led_cdev;
+
+        if (IS_ERR_OR_NULL(v4l2_flash))
+                return;
+
+        sd = &v4l2_flash->sd;
+        led_cdev = &v4l2_flash->fled_cdev->led_cdev;
+
+        v4l2_async_unregister_subdev(sd);
+
+        if (sd->of_node)
+                of_node_put(sd->of_node);
+        else
+                of_node_put(led_cdev->dev->of_node);
+
+        v4l2_ctrl_handler_free(sd->ctrl_handler);
+        media_entity_cleanup(&sd->entity);
+}
+EXPORT_SYMBOL_GPL(v4l2_flash_release);
+
+MODULE_AUTHOR("Jacek Anaszewski <j.anaszewski@samsung.com>");
+MODULE_DESCRIPTION("V4L2 Flash sub-device helpers");
+MODULE_LICENSE("GPL v2");
diff --git a/include/media/v4l2-flash-led-class.h b/include/media/v4l2-flash-led-class.h
new file mode 100644
index 000000000000..098236c083b8
--- /dev/null
+++ b/include/media/v4l2-flash-led-class.h
@@ -0,0 +1,148 @@
+/*
+ * V4L2 flash LED sub-device registration helpers.
+ *
+ *      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 _V4L2_FLASH_H
+#define _V4L2_FLASH_H
+
+#include <media/v4l2-ctrls.h>
+#include <media/v4l2-subdev.h>
+
+struct led_classdev_flash;
+struct led_classdev;
+struct v4l2_flash;
+enum led_brightness;
+
+/*
+ * struct v4l2_flash_ctrl_data - flash control initialization data, filled
+ *                              basing on the features declared by the LED flash
+ *                              class driver in the v4l2_flash_config
+ * @config:     initialization data for a control
+ * @cid:        contains v4l2 flash control id if the config
+ *              field was initialized, 0 otherwise
+ */
+struct v4l2_flash_ctrl_data {
+        struct v4l2_ctrl_config config;
+        u32 cid;
+};
+
+struct v4l2_flash_ops {
+        /* setup strobing the flash by hardware pin state assertion */
+        int (*external_strobe_set)(struct v4l2_flash *v4l2_flash,
+                                        bool enable);
+        /* convert intensity to brightness in a device specific manner */
+        enum led_brightness (*intensity_to_led_brightness)
+                (struct v4l2_flash *v4l2_flash, s32 intensity);
+        /* convert brightness to intensity in a device specific manner */
+        s32 (*led_brightness_to_intensity)
+                (struct v4l2_flash *v4l2_flash, enum led_brightness);
+};
+
+/**
+ * struct v4l2_flash_config - V4L2 Flash sub-device initialization data
+ * @dev_name:                   the name of the media entity,
+                                unique in the system
+ * @torch_intensity:            constraints for the LED in torch mode
+ * @indicator_intensity:        constraints for the indicator LED
+ * @flash_faults:               bitmask of flash faults that the LED flash class
+                                device can report; corresponding LED_FAULT* bit
+                                definitions are available in the header file
+                                <linux/led-class-flash.h>
+ * @has_external_strobe:        external strobe capability
+ */
+struct v4l2_flash_config {
+        char dev_name[32];
+        struct led_flash_setting torch_intensity;
+        struct led_flash_setting indicator_intensity;
+        u32 flash_faults;
+        unsigned int has_external_strobe:1;
+};
+
+/**
+ * struct v4l2_flash - Flash sub-device context
+ * @fled_cdev:          LED flash class device controlled by this sub-device
+ * @iled_cdev:          LED class device representing indicator LED associated
+ *                      with the LED flash class device
+ * @ops:                V4L2 specific flash ops
+ * @sd:                 V4L2 sub-device
+ * @hdl:                flash controls handler
+ * @ctrls:              array of pointers to controls, whose values define
+ *                      the sub-device state
+ */
+struct v4l2_flash {
+        struct led_classdev_flash *fled_cdev;
+        struct led_classdev_flash *iled_cdev;
+        const struct v4l2_flash_ops *ops;
+
+        struct v4l2_subdev sd;
+        struct v4l2_ctrl_handler hdl;
+        struct v4l2_ctrl **ctrls;
+};
+
+static inline struct v4l2_flash *v4l2_subdev_to_v4l2_flash(
+                                                        struct v4l2_subdev *sd)
+{
+        return container_of(sd, struct v4l2_flash, sd);
+}
+
+static inline struct v4l2_flash *v4l2_ctrl_to_v4l2_flash(struct v4l2_ctrl *c)
+{
+        return container_of(c->handler, struct v4l2_flash, hdl);
+}
+
+#if IS_ENABLED(CONFIG_V4L2_FLASH_LED_CLASS)
+/**
+ * v4l2_flash_init - initialize V4L2 flash led sub-device
+ * @dev:        flash device, e.g. an I2C device
+ * @of_node:    of_node of the LED, may be NULL if the same as device's
+ * @fled_cdev:  LED flash class device to wrap
+ * @iled_cdev:  LED flash class device representing indicator LED associated
+ *              with fled_cdev, may be NULL
+ * @flash_ops:  V4L2 Flash device ops
+ * @config:     initialization data for V4L2 Flash sub-device
+ *
+ * Create V4L2 Flash sub-device wrapping given LED subsystem device.
+ *
+ * Returns: A valid pointer, or, when an error occurs, the return
+ * value is encoded using ERR_PTR(). Use IS_ERR() to check and
+ * PTR_ERR() to obtain the numeric return value.
+ */
+struct v4l2_flash *v4l2_flash_init(
+        struct device *dev, struct device_node *of_node,
+        struct led_classdev_flash *fled_cdev,
+        struct led_classdev_flash *iled_cdev,
+        const struct v4l2_flash_ops *ops,
+        struct v4l2_flash_config *config);
+
+/**
+ * v4l2_flash_release - release V4L2 Flash sub-device
+ * @flash: the V4L2 Flash sub-device to release
+ *
+ * Release V4L2 Flash sub-device.
+ */
+void v4l2_flash_release(struct v4l2_flash *v4l2_flash);
+
+#else
+static inline struct v4l2_flash *v4l2_flash_init(
+        struct device *dev, struct device_node *of_node,
+        struct led_classdev_flash *fled_cdev,
+        struct led_classdev_flash *iled_cdev,
+        const struct v4l2_flash_ops *ops,
+        struct v4l2_flash_config *config)
+{
+        return NULL;
+}
+
+static inline void v4l2_flash_release(struct v4l2_flash *v4l2_flash)
+{
+}
+#endif /* CONFIG_V4L2_FLASH_LED_CLASS */
+
+#endif /* _V4L2_FLASH_H */