On 11/28/2014 10:17 AM, Jacek Anaszewski wrote:
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.anaszew...@samsung.com>
Acked-by: Kyungmin Park <kyungmin.p...@samsung.com>
Cc: Sakari Ailus <sakari.ai...@iki.fi>
Cc: Hans Verkuil <hans.verk...@cisco.com>
---
  drivers/media/v4l2-core/Kconfig      |   11 +
  drivers/media/v4l2-core/Makefile     |    2 +
  drivers/media/v4l2-core/v4l2-flash.c |  516 ++++++++++++++++++++++++++++++++++
  include/media/v4l2-flash.h           |  138 +++++++++
  4 files changed, 667 insertions(+)
  create mode 100644 drivers/media/v4l2-core/v4l2-flash.c
  create mode 100644 include/media/v4l2-flash.h

diff --git a/drivers/media/v4l2-core/Kconfig b/drivers/media/v4l2-core/Kconfig
index ba7e21a..f034f1a 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 "Enable support for Flash sub-devices"
+       depends on VIDEO_V4L2_SUBDEV_API
+       depends on LEDS_CLASS_FLASH
+       ---help---
+         Say Y here to enable support for Flash sub-devices, which allow
+         to control LED class devices with use of V4L2 Flash controls.
+
+         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 63d29f2..44e858c 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-$(CONFIG_V4L2_FLASH_LED_CLASS) += v4l2-flash.o
+
  obj-$(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.c 
b/drivers/media/v4l2-core/v4l2-flash.c
new file mode 100644
index 0000000..f5075b0
--- /dev/null
+++ b/drivers/media/v4l2-core/v4l2-flash.c
@@ -0,0 +1,516 @@
+/*
+ * V4L2 Flash LED sub-device registration helpers.
+ *
+ *     Copyright (C) 2014 Samsung Electronics Co., Ltd
+ *     Author: Jacek Anaszewski <j.anaszew...@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/slab.h>
+#include <linux/types.h>
+#include <media/v4l2-flash.h>
+
+#define has_flash_op(v4l2_flash, op)                   \
+       (v4l2_flash && v4l2_flash->ops->op)
+
+#define call_flash_op(v4l2_flash, op, args...)         \
+               (has_flash_op(v4l2_flash, op) ?         \
+                       v4l2_flash->ops->op(args) :       \
+                       -EINVAL)
+
+static inline enum led_brightness v4l2_flash_intensity_to_led_brightness(
+                                       struct v4l2_ctrl *ctrl,
+                                       s32 intensity)
+{
+       s64 __intensity = intensity - ctrl->minimum;
+
+       do_div(__intensity, ctrl->step);
+
+       return __intensity + 1;
+}
+
+static inline s32 v4l2_flash_led_brightness_to_intensity(
+                                       struct v4l2_ctrl *ctrl,
+                                       enum led_brightness brightness)
+{
+       return ((brightness - 1) * ctrl->step) + ctrl->minimum;
+}
+
+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 *flash = v4l2_flash->flash;
+       struct led_classdev *led_cdev = &flash->led_cdev;
+       struct v4l2_ctrl **ctrls = v4l2_flash->ctrls;
+       bool is_strobing;
+       int ret;
+
+       switch (c->id) {
+       case V4L2_CID_FLASH_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 setting
+                * has changed.
+                */
+               if (ctrls[LED_MODE]->val == V4L2_FLASH_LED_MODE_TORCH) {
+                       ret = led_update_brightness(led_cdev);
+                       if (ret < 0)
+                               return ret;
+                       c->val = v4l2_flash_led_brightness_to_intensity(
+                                                       ctrls[TORCH_INTENSITY],
+                                                       led_cdev->brightness);
+               }
+               return 0;
+       case V4L2_CID_FLASH_INDICATOR_INTENSITY:
+               ret = led_update_brightness(led_cdev);
+               if (ret < 0)
+                       return ret;
+               c->val = v4l2_flash_led_brightness_to_intensity(
+                                               ctrls[INDICATOR_INTENSITY],
+                                               led_cdev->brightness);
+               return 0;
+       case V4L2_CID_FLASH_INTENSITY:
+               ret = led_update_flash_brightness(flash);
+               if (ret < 0)
+                       return ret;
+               /* no conversion is needed */
+               c->val = flash->brightness.val;
+               return 0;
+       case V4L2_CID_FLASH_STROBE_STATUS:
+               ret = led_get_flash_strobe(flash, &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(flash, &c->val);
+       case V4L2_CID_FLASH_SYNC_STROBE:
+               c->val = flash->sync_strobe;
+               return 0;
+       default:
+               return -EINVAL;
+       }
+}
+
+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 *flash = v4l2_flash->flash;
+       struct led_classdev *led_cdev = &flash->led_cdev;
+       struct v4l2_ctrl **ctrls = v4l2_flash->ctrls;
+       enum led_brightness brightness;
+       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(flash, false);
+               case V4L2_FLASH_LED_MODE_FLASH:
+                       /* Turn the torch LED off */
+                       led_set_brightness(led_cdev, LED_OFF);
+                       external_strobe = (ctrls[STROBE_SOURCE]->val ==
+                                       V4L2_FLASH_STROBE_SOURCE_EXTERNAL);
+
+                       if (has_flash_op(v4l2_flash, external_strobe_set))
+                               ret = call_flash_op(v4l2_flash,
+                                               external_strobe_set, v4l2_flash,
+                                               external_strobe);
+                       return ret;
+               case V4L2_FLASH_LED_MODE_TORCH:
+                       /* Stop flash strobing */
+                       ret = led_set_flash_strobe(flash, false);
+                       if (ret < 0)
+                               return ret;
+
+                       brightness =
+                               v4l2_flash_intensity_to_led_brightness(
+                                               ctrls[TORCH_INTENSITY],
+                                               ctrls[TORCH_INTENSITY]->val);
+                       led_set_brightness(led_cdev, brightness);
+                       return 0;
+               }
+               break;
+       case V4L2_CID_FLASH_STROBE_SOURCE:
+               external_strobe = (c->val == V4L2_FLASH_STROBE_SOURCE_EXTERNAL);
+
+               return call_flash_op(v4l2_flash, external_strobe_set,
+                                       v4l2_flash, external_strobe);
+       case V4L2_CID_FLASH_STROBE:
+               if (ctrls[LED_MODE]->val != V4L2_FLASH_LED_MODE_FLASH ||
+                   ctrls[STROBE_SOURCE]->val !=
+                                       V4L2_FLASH_STROBE_SOURCE_SOFTWARE)
+                       return -EINVAL;
+               return led_set_flash_strobe(flash, true);
+       case V4L2_CID_FLASH_STROBE_STOP:
+               if (ctrls[LED_MODE]->val != V4L2_FLASH_LED_MODE_FLASH ||
+                   ctrls[STROBE_SOURCE]->val !=
+                                       V4L2_FLASH_STROBE_SOURCE_SOFTWARE)
+                       return -EINVAL;
+               return led_set_flash_strobe(flash, false);
+       case V4L2_CID_FLASH_TIMEOUT:
+               /* no conversion is needed */
+               return led_set_flash_timeout(flash, c->val);
+       case V4L2_CID_FLASH_INTENSITY:
+               /* no conversion is needed */
+               return led_set_flash_brightness(flash, c->val);
+       case V4L2_CID_FLASH_INDICATOR_INTENSITY:
+               brightness = v4l2_flash_intensity_to_led_brightness(
+                                               ctrls[INDICATOR_INTENSITY],
+                                               c->val);
+               led_set_brightness(led_cdev, brightness);
+               return 0;
+       case V4L2_CID_FLASH_TORCH_INTENSITY:
+               /*
+                * If not in MODE_TORCH don't call led-class brightness_set
+                * op, as it would result in turning the torch led on.
+                * Instead the value is cached only and will be written
+                * to the device upon transition to MODE_TORCH.
+                */
+               if (ctrls[LED_MODE]->val == V4L2_FLASH_LED_MODE_TORCH) {
+                       brightness =
+                               v4l2_flash_intensity_to_led_brightness(
+                                                       ctrls[TORCH_INTENSITY],
+                                                       c->val);
+                       led_set_brightness(led_cdev, brightness);
+               }
+               return 0;
+       case V4L2_CID_FLASH_SYNC_STROBE:
+               flash->sync_strobe = c->val;
+               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 fill_ctrl_init_data(struct v4l2_flash *v4l2_flash,
+                         struct v4l2_flash_ctrl_config *flash_cfg,
+                         struct v4l2_flash_ctrl_data *ctrl_init_data)
+{
+       struct led_classdev_flash *flash = v4l2_flash->flash;
+       const struct led_flash_ops *flash_ops = flash->ops;
+       struct led_classdev *led_cdev = &flash->led_cdev;
+       struct v4l2_ctrl_config *ctrl_cfg;
+       u32 mask;
+       s64 max;
+
+       /* 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;

I didn't take into account the case when there is no LED_DEV_CAP_FLASH
flag set but there is has_indicator flag set in the
v4l2_flash_ctrl_config. In fact this is the only valid arrangement
in the new approach where the indicator led will have its own
LED Flash class device and the related v4l2_subdev.

Actually has_indicator is the residue after previous version of the
patch set. It should be renamed to e.g. indicator_led. Similarly
indicator_intensity should be removed, torch_intensity renamed to
something more generic for both torch and indicator leds e.g. led_intensity or just intensity like in case of proposed
new leds/common.txt bindings where the property max-microamp doesn't
have any additional segment and there is flash-max-microamp property
for flash leds. Mode and torch intensity controls also shouldn't be
created for indicator leds.

Summarizing - indicator led should have maximum two controls:
V4L2_CID_FLASH_INDICATOR_INTENSITY and V4L2_CID_FLASH_FAULT

Best Regards,
Jacek Anaszewski

+       ctrl_init_data[LED_MODE].supported = true;
+       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].supported = true;
+       ctrl_init_data[TORCH_INTENSITY].config = flash_cfg->torch_intensity;
+       ctrl_cfg = &ctrl_init_data[TORCH_INTENSITY].config;
+       ctrl_cfg->id = V4L2_CID_FLASH_TORCH_INTENSITY;
+       ctrl_cfg->flags = V4L2_CTRL_FLAG_VOLATILE;
+
+       if (!(led_cdev->flags & LED_DEV_CAP_FLASH))
+               return;
+
+       /* Init FLASH_STROBE_SOURCE ctrl data */
+       mask = 1 << V4L2_FLASH_STROBE_SOURCE_SOFTWARE;
+       if (flash_cfg->has_external_strobe) {
+               mask |= 1 << V4L2_FLASH_STROBE_SOURCE_EXTERNAL;
+               max = V4L2_FLASH_STROBE_SOURCE_EXTERNAL;
+       } else {
+               max = V4L2_FLASH_STROBE_SOURCE_SOFTWARE;
+       }
+
+       ctrl_init_data[STROBE_SOURCE].supported = true;
+       ctrl_cfg = &ctrl_init_data[STROBE_SOURCE].config;
+       ctrl_cfg->id = V4L2_CID_FLASH_STROBE_SOURCE;
+       ctrl_cfg->max = max;
+       ctrl_cfg->menu_skip_mask = ~mask;
+       ctrl_cfg->def = V4L2_FLASH_STROBE_SOURCE_SOFTWARE;
+
+       /* Init FLASH_STROBE ctrl data */
+       ctrl_init_data[FLASH_STROBE].supported = true;
+       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].supported = true;
+       ctrl_cfg = &ctrl_init_data[STROBE_STOP].config;
+       ctrl_cfg->id = V4L2_CID_FLASH_STROBE_STOP;
+
+       /* Init STROBE_STATUS ctrl data */
+       if (flash_ops->strobe_get) {
+               ctrl_init_data[STROBE_STATUS].supported = true;
+               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 (flash_ops->timeout_set) {
+               ctrl_init_data[FLASH_TIMEOUT].supported = true;
+               ctrl_init_data[FLASH_TIMEOUT].config = flash_cfg->flash_timeout;
+               ctrl_cfg = &ctrl_init_data[FLASH_TIMEOUT].config;
+               ctrl_cfg->id = V4L2_CID_FLASH_TIMEOUT;
+               ctrl_cfg->flags = V4L2_CTRL_FLAG_VOLATILE;
+       }
+
+       /* Init FLASH_INTENSITY ctrl data */
+       if (flash_ops->flash_brightness_set) {
+               ctrl_init_data[FLASH_INTENSITY].supported = true;
+               ctrl_init_data[FLASH_INTENSITY].config =
+                                       flash_cfg->flash_intensity;
+               ctrl_cfg = &ctrl_init_data[FLASH_INTENSITY].config;
+               ctrl_cfg->id = V4L2_CID_FLASH_INTENSITY;
+               ctrl_cfg->flags = V4L2_CTRL_FLAG_VOLATILE;
+       }
+
+       /* Init INDICATOR_INTENSITY ctrl data */
+       if (flash_cfg->has_indicator) {
+               ctrl_init_data[INDICATOR_INTENSITY].supported = true;
+               ctrl_init_data[INDICATOR_INTENSITY].config =
+                                       flash_cfg->indicator_intensity;
+               ctrl_cfg = &ctrl_init_data[INDICATOR_INTENSITY].config;
+               ctrl_cfg->id = V4L2_CID_FLASH_INDICATOR_INTENSITY;
+               ctrl_cfg->flags = V4L2_CTRL_FLAG_VOLATILE;
+       }
+
+       /* Init FLASH_FAULT ctrl data */
+       if (flash_cfg->flash_faults) {
+               ctrl_init_data[FLASH_FAULT].supported = true;
+               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;
+       }
+
+       if (led_cdev->flags & LED_DEV_CAP_COMPOUND) {
+               ctrl_init_data[SYNC_STROBE].supported = true;
+               ctrl_cfg = &ctrl_init_data[SYNC_STROBE].config;
+               ctrl_cfg->id = V4L2_CID_FLASH_SYNC_STROBE;
+               ctrl_cfg->flags = V4L2_CTRL_FLAG_VOLATILE;
+       }
+}
+
+static int v4l2_flash_init_controls(struct v4l2_flash *v4l2_flash,
+                               struct v4l2_flash_ctrl_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;
+
+       /* 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;
+
+       memset(ctrl_init_data, 0, sizeof(*ctrl_init_data));
+
+       fill_ctrl_init_data(v4l2_flash, flash_cfg, ctrl_init_data);
+
+       for (i = 0; i < NUM_FLASH_CTRLS; ++i)
+               if (ctrl_init_data[i].supported)
+                       ++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].supported)
+                       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;
+}
+
+/*
+ * 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 *flash = v4l2_flash->flash;
+       struct led_classdev *led_cdev = &flash->led_cdev;
+       int ret = 0;
+
+       mutex_lock(&led_cdev->led_access);
+
+       if (!v4l2_fh_is_singular(&fh->vfh)) {
+               ret = -EBUSY;
+               goto unlock;
+       }
+
+       led_sysfs_disable(led_cdev);
+
+unlock:
+       mutex_unlock(&led_cdev->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 *flash = v4l2_flash->flash;
+       struct led_classdev *led_cdev = &flash->led_cdev;
+       int ret = 0;
+
+       mutex_lock(&led_cdev->led_access);
+
+       if (has_flash_op(v4l2_flash, external_strobe_set))
+               ret = call_flash_op(v4l2_flash, external_strobe_set,
+                               v4l2_flash, false);
+       led_sysfs_enable(led_cdev);
+
+       mutex_unlock(&led_cdev->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 led_classdev_flash *flash,
+                                  const struct v4l2_flash_ops *ops,
+                                  struct v4l2_flash_ctrl_config *config)
+{
+       struct v4l2_flash *v4l2_flash;
+       struct led_classdev *led_cdev = &flash->led_cdev;
+       struct v4l2_subdev *sd;
+       int ret;
+
+       if (!flash || !ops || !config)
+               return ERR_PTR(-EINVAL);
+
+       v4l2_flash = kzalloc(sizeof(*v4l2_flash), GFP_KERNEL);
+       if (!v4l2_flash)
+               return ERR_PTR(-ENOMEM);
+
+       sd = &v4l2_flash->sd;
+       v4l2_flash->flash = flash;
+       v4l2_flash->ops = ops;
+       sd->dev = led_cdev->dev->parent;
+       v4l2_subdev_init(sd, &v4l2_flash_subdev_ops);
+       sd->internal_ops = &v4l2_flash_subdev_internal_ops;
+       sd->flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
+       snprintf(sd->name, sizeof(sd->name), led_cdev->name);
+
+       ret = v4l2_flash_init_controls(v4l2_flash, config);
+       if (ret < 0)
+               goto err_init_controls;
+
+       ret = media_entity_init(&sd->entity, 0, NULL, 0);
+       if (ret < 0)
+               goto err_init_entity;
+
+       sd->entity.type = MEDIA_ENT_T_V4L2_SUBDEV_FLASH;
+
+       ret = v4l2_async_register_subdev(sd);
+       if (ret < 0)
+               goto err_init_entity;
+
+       return v4l2_flash;
+
+err_init_entity:
+       media_entity_cleanup(&sd->entity);
+err_init_controls:
+       v4l2_ctrl_handler_free(sd->ctrl_handler);
+       kfree(v4l2_flash);
+
+       return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_GPL(v4l2_flash_init);
+
+void v4l2_flash_release(struct v4l2_flash *v4l2_flash)
+{
+       struct v4l2_subdev *sd = &v4l2_flash->sd;
+
+       if (!v4l2_flash)
+               return;
+
+       v4l2_async_unregister_subdev(sd);
+       media_entity_cleanup(&sd->entity);
+       v4l2_ctrl_handler_free(sd->ctrl_handler);
+       kfree(v4l2_flash);
+}
+EXPORT_SYMBOL_GPL(v4l2_flash_release);
+
+MODULE_AUTHOR("Jacek Anaszewski <j.anaszew...@samsung.com>");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("V4L2 Flash sub-device helpers");
diff --git a/include/media/v4l2-flash.h b/include/media/v4l2-flash.h
new file mode 100644
index 0000000..1e18df5
--- /dev/null
+++ b/include/media/v4l2-flash.h
@@ -0,0 +1,138 @@
+/*
+ * V4L2 Flash LED sub-device registration helpers.
+ *
+ *     Copyright (C) 2014 Samsung Electronics Co., Ltd
+ *     Author: Jacek Anaszewski <j.anaszew...@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-device.h>
+#include <media/v4l2-dev.h>
+#include <media/v4l2-event.h>
+#include <media/v4l2-ioctl.h>
+
+struct led_classdev_flash;
+struct led_classdev;
+struct v4l2_flash;
+enum led_brightness;
+
+enum ctrl_init_data_id {
+       LED_MODE,
+       TORCH_INTENSITY,
+       STROBE_SOURCE,
+       FLASH_STROBE,
+       STROBE_STOP,
+       STROBE_STATUS,
+       FLASH_TIMEOUT,
+       FLASH_INTENSITY,
+       INDICATOR_INTENSITY,
+       FLASH_FAULT,
+       SYNC_STROBE,
+       NUM_FLASH_CTRLS,
+};
+
+/*
+ * struct v4l2_flash_ctrl_data - flash control initialization data -
+ *                              filled basing on the features declared
+ *                              by the LED Flash class driver
+ * @config:    initialization data for a control
+ * @supported: indicates whether a control is supported
+ *             by the LED Flash class driver
+ */
+struct v4l2_flash_ctrl_data {
+       struct v4l2_ctrl_config config;
+       bool supported;
+};
+
+struct v4l2_flash_ops {
+       /* setup strobing the flash by hardware pin state assertion */
+       int (*external_strobe_set)(struct v4l2_flash *v4l2_flash,
+                                       bool enable);
+};
+
+/**
+ * struct v4l2_flash_ctrl_config - V4L2 Flash controls initialization data
+ * @torch_intensity:           V4L2_CID_FLASH_TORCH_INTENSITY constraints
+ * @flash_intensity:           V4L2_CID_FLASH_INTENSITY constraints
+ * @indicator_intensity:       V4L2_CID_FLASH_INDICATOR_INTENSITY constraints
+ * @flash_timeout:             V4L2_CID_FLASH_TIMEOUT constraints
+ * @flash_fault:               possible flash faults
+ * @has_external_strobe:       external strobe capability
+ */
+struct v4l2_flash_ctrl_config {
+       struct v4l2_ctrl_config torch_intensity;
+       struct v4l2_ctrl_config flash_intensity;
+       struct v4l2_ctrl_config indicator_intensity;
+       struct v4l2_ctrl_config flash_timeout;
+       u32 flash_faults;
+       bool has_external_strobe:1;
+       bool has_indicator:1;
+};
+
+/**
+ * struct v4l2_flash - Flash sub-device context
+ * @flash:             LED Flash Class device controlled by this sub-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 *flash;
+       const struct v4l2_flash_ops *ops;
+
+       struct v4l2_subdev sd;
+       struct v4l2_ctrl_handler hdl;
+       struct v4l2_ctrl *ctrls[STROBE_SOURCE + 1];
+};
+
+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
+ * @led_fdev:  the LED Flash Class device to wrap
+ * @config:    initialization data for V4L2 Flash controls
+ * @flash_ops: V4L2 Flash device ops
+ *
+ * Create V4L2 subdev 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 led_classdev_flash *led_fdev,
+                                  const struct v4l2_flash_ops *ops,
+                                  struct v4l2_flash_ctrl_config *config);
+
+/**
+ * v4l2_flash_release - release V4L2 Flash sub-device
+ * @flash: the V4L2 Flash device to release
+ *
+ * Release V4L2 flash led subdev.
+ */
+void v4l2_flash_release(struct v4l2_flash *v4l2_flash);
+
+#else
+#define v4l2_flash_init(led_cdev, ops, config) (NULL)
+#define v4l2_flash_release(v4l2_flash)
+#endif /* CONFIG_V4L2_FLASH_LED_CLASS */
+
+#endif /* _V4L2_FLASH_H */


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