ipvs: add backup_only flag to avoid loops

[linux/fpc-iii.git] / include / media / v4l2-ctrls.h

/*
    V4L2 controls support header.

    Copyright (C) 2010  Hans Verkuil <hverkuil@xs4all.nl>

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#ifndef _V4L2_CTRLS_H
#define _V4L2_CTRLS_H

#include <linux/list.h>
#include <linux/videodev2.h>

/* forward references */
struct file;
struct v4l2_ctrl_handler;
struct v4l2_ctrl_helper;
struct v4l2_ctrl;
struct video_device;
struct v4l2_subdev;
struct v4l2_subscribed_event;
struct v4l2_fh;
struct poll_table_struct;

/** struct v4l2_ctrl_ops - The control operations that the driver has to provide.
  * @g_volatile_ctrl: Get a new value for this control. Generally only relevant
  *             for volatile (and usually read-only) controls such as a control
  *             that returns the current signal strength which changes
  *             continuously.
  *             If not set, then the currently cached value will be returned.
  * @try_ctrl:  Test whether the control's value is valid. Only relevant when
  *             the usual min/max/step checks are not sufficient.
  * @s_ctrl:    Actually set the new control value. s_ctrl is compulsory. The
  *             ctrl->handler->lock is held when these ops are called, so no
  *             one else can access controls owned by that handler.
  */
struct v4l2_ctrl_ops {
        int (*g_volatile_ctrl)(struct v4l2_ctrl *ctrl);
        int (*try_ctrl)(struct v4l2_ctrl *ctrl);
        int (*s_ctrl)(struct v4l2_ctrl *ctrl);
};

typedef void (*v4l2_ctrl_notify_fnc)(struct v4l2_ctrl *ctrl, void *priv);

/** struct v4l2_ctrl - The control structure.
  * @node:      The list node.
  * @ev_subs:   The list of control event subscriptions.
  * @handler:   The handler that owns the control.
  * @cluster:   Point to start of cluster array.
  * @ncontrols: Number of controls in cluster array.
  * @done:      Internal flag: set for each processed control.
  * @is_new:    Set when the user specified a new value for this control. It
  *             is also set when called from v4l2_ctrl_handler_setup. Drivers
  *             should never set this flag.
  * @is_private: If set, then this control is private to its handler and it
  *             will not be added to any other handlers. Drivers can set
  *             this flag.
  * @is_auto:   If set, then this control selects whether the other cluster
  *             members are in 'automatic' mode or 'manual' mode. This is
  *             used for autogain/gain type clusters. Drivers should never
  *             set this flag directly.
  * @has_volatiles: If set, then one or more members of the cluster are volatile.
  *             Drivers should never touch this flag.
  * @call_notify: If set, then call the handler's notify function whenever the
  *             control's value changes.
  * @manual_mode_value: If the is_auto flag is set, then this is the value
  *             of the auto control that determines if that control is in
  *             manual mode. So if the value of the auto control equals this
  *             value, then the whole cluster is in manual mode. Drivers should
  *             never set this flag directly.
  * @ops:       The control ops.
  * @id:        The control ID.
  * @name:      The control name.
  * @type:      The control type.
  * @minimum:   The control's minimum value.
  * @maximum:   The control's maximum value.
  * @default_value: The control's default value.
  * @step:      The control's step value for non-menu controls.
  * @menu_skip_mask: The control's skip mask for menu controls. This makes it
  *             easy to skip menu items that are not valid. If bit X is set,
  *             then menu item X is skipped. Of course, this only works for
  *             menus with <= 32 menu items. There are no menus that come
  *             close to that number, so this is OK. Should we ever need more,
  *             then this will have to be extended to a u64 or a bit array.
  * @qmenu:     A const char * array for all menu items. Array entries that are
  *             empty strings ("") correspond to non-existing menu items (this
  *             is in addition to the menu_skip_mask above). The last entry
  *             must be NULL.
  * @flags:     The control's flags.
  * @cur:       The control's current value.
  * @val:       The control's new s32 value.
  * @val64:     The control's new s64 value.
  * @string:    The control's new string value.
  * @priv:      The control's private pointer. For use by the driver. It is
  *             untouched by the control framework. Note that this pointer is
  *             not freed when the control is deleted. Should this be needed
  *             then a new internal bitfield can be added to tell the framework
  *             to free this pointer.
  */
struct v4l2_ctrl {
        /* Administrative fields */
        struct list_head node;
        struct list_head ev_subs;
        struct v4l2_ctrl_handler *handler;
        struct v4l2_ctrl **cluster;
        unsigned ncontrols;
        unsigned int done:1;

        unsigned int is_new:1;
        unsigned int is_private:1;
        unsigned int is_auto:1;
        unsigned int has_volatiles:1;
        unsigned int call_notify:1;
        unsigned int manual_mode_value:8;

        const struct v4l2_ctrl_ops *ops;
        u32 id;
        const char *name;
        enum v4l2_ctrl_type type;
        s32 minimum, maximum, default_value;
        union {
                u32 step;
                u32 menu_skip_mask;
        };
        union {
                const char * const *qmenu;
                const s64 *qmenu_int;
        };
        unsigned long flags;
        union {
                s32 val;
                s64 val64;
                char *string;
        } cur;
        union {
                s32 val;
                s64 val64;
                char *string;
        };
        void *priv;
};

/** struct v4l2_ctrl_ref - The control reference.
  * @node:      List node for the sorted list.
  * @next:      Single-link list node for the hash.
  * @ctrl:      The actual control information.
  * @helper:    Pointer to helper struct. Used internally in prepare_ext_ctrls().
  *
  * Each control handler has a list of these refs. The list_head is used to
  * keep a sorted-by-control-ID list of all controls, while the next pointer
  * is used to link the control in the hash's bucket.
  */
struct v4l2_ctrl_ref {
        struct list_head node;
        struct v4l2_ctrl_ref *next;
        struct v4l2_ctrl *ctrl;
        struct v4l2_ctrl_helper *helper;
};

/** struct v4l2_ctrl_handler - The control handler keeps track of all the
  * controls: both the controls owned by the handler and those inherited
  * from other handlers.
  * @_lock:     Default for "lock".
  * @lock:      Lock to control access to this handler and its controls.
  *             May be replaced by the user right after init.
  * @ctrls:     The list of controls owned by this handler.
  * @ctrl_refs: The list of control references.
  * @cached:    The last found control reference. It is common that the same
  *             control is needed multiple times, so this is a simple
  *             optimization.
  * @buckets:   Buckets for the hashing. Allows for quick control lookup.
  * @notify:    A notify callback that is called whenever the control changes value.
  *             Note that the handler's lock is held when the notify function
  *             is called!
  * @notify_priv: Passed as argument to the v4l2_ctrl notify callback.
  * @nr_of_buckets: Total number of buckets in the array.
  * @error:     The error code of the first failed control addition.
  */
struct v4l2_ctrl_handler {
        struct mutex _lock;
        struct mutex *lock;
        struct list_head ctrls;
        struct list_head ctrl_refs;
        struct v4l2_ctrl_ref *cached;
        struct v4l2_ctrl_ref **buckets;
        v4l2_ctrl_notify_fnc notify;
        void *notify_priv;
        u16 nr_of_buckets;
        int error;
};

/** struct v4l2_ctrl_config - Control configuration structure.
  * @ops:       The control ops.
  * @id:        The control ID.
  * @name:      The control name.
  * @type:      The control type.
  * @min:       The control's minimum value.
  * @max:       The control's maximum value.
  * @step:      The control's step value for non-menu controls.
  * @def:       The control's default value.
  * @flags:     The control's flags.
  * @menu_skip_mask: The control's skip mask for menu controls. This makes it
  *             easy to skip menu items that are not valid. If bit X is set,
  *             then menu item X is skipped. Of course, this only works for
  *             menus with <= 32 menu items. There are no menus that come
  *             close to that number, so this is OK. Should we ever need more,
  *             then this will have to be extended to a u64 or a bit array.
  * @qmenu:     A const char * array for all menu items. Array entries that are
  *             empty strings ("") correspond to non-existing menu items (this
  *             is in addition to the menu_skip_mask above). The last entry
  *             must be NULL.
  * @is_private: If set, then this control is private to its handler and it
  *             will not be added to any other handlers.
  */
struct v4l2_ctrl_config {
        const struct v4l2_ctrl_ops *ops;
        u32 id;
        const char *name;
        enum v4l2_ctrl_type type;
        s32 min;
        s32 max;
        u32 step;
        s32 def;
        u32 flags;
        u32 menu_skip_mask;
        const char * const *qmenu;
        const s64 *qmenu_int;
        unsigned int is_private:1;
};

/** v4l2_ctrl_fill() - Fill in the control fields based on the control ID.
  *
  * This works for all standard V4L2 controls.
  * For non-standard controls it will only fill in the given arguments
  * and @name will be NULL.
  *
  * This function will overwrite the contents of @name, @type and @flags.
  * The contents of @min, @max, @step and @def may be modified depending on
  * the type.
  *
  * Do not use in drivers! It is used internally for backwards compatibility
  * control handling only. Once all drivers are converted to use the new
  * control framework this function will no longer be exported.
  */
void v4l2_ctrl_fill(u32 id, const char **name, enum v4l2_ctrl_type *type,
                    s32 *min, s32 *max, s32 *step, s32 *def, u32 *flags);


/** v4l2_ctrl_handler_init() - Initialize the control handler.
  * @hdl:       The control handler.
  * @nr_of_controls_hint: A hint of how many controls this handler is
  *             expected to refer to. This is the total number, so including
  *             any inherited controls. It doesn't have to be precise, but if
  *             it is way off, then you either waste memory (too many buckets
  *             are allocated) or the control lookup becomes slower (not enough
  *             buckets are allocated, so there are more slow list lookups).
  *             It will always work, though.
  *
  * Returns an error if the buckets could not be allocated. This error will
  * also be stored in @hdl->error.
  */
int v4l2_ctrl_handler_init(struct v4l2_ctrl_handler *hdl,
                           unsigned nr_of_controls_hint);

/** v4l2_ctrl_handler_free() - Free all controls owned by the handler and free
  * the control list.
  * @hdl:       The control handler.
  *
  * Does nothing if @hdl == NULL.
  */
void v4l2_ctrl_handler_free(struct v4l2_ctrl_handler *hdl);

/** v4l2_ctrl_handler_setup() - Call the s_ctrl op for all controls belonging
  * to the handler to initialize the hardware to the current control values.
  * @hdl:       The control handler.
  *
  * Button controls will be skipped, as are read-only controls.
  *
  * If @hdl == NULL, then this just returns 0.
  */
int v4l2_ctrl_handler_setup(struct v4l2_ctrl_handler *hdl);

/** v4l2_ctrl_handler_log_status() - Log all controls owned by the handler.
  * @hdl:       The control handler.
  * @prefix:    The prefix to use when logging the control values. If the
  *             prefix does not end with a space, then ": " will be added
  *             after the prefix. If @prefix == NULL, then no prefix will be
  *             used.
  *
  * For use with VIDIOC_LOG_STATUS.
  *
  * Does nothing if @hdl == NULL.
  */
void v4l2_ctrl_handler_log_status(struct v4l2_ctrl_handler *hdl,
                                  const char *prefix);

/** v4l2_ctrl_new_custom() - Allocate and initialize a new custom V4L2
  * control.
  * @hdl:       The control handler.
  * @cfg:       The control's configuration data.
  * @priv:      The control's driver-specific private data.
  *
  * If the &v4l2_ctrl struct could not be allocated then NULL is returned
  * and @hdl->error is set to the error code (if it wasn't set already).
  */
struct v4l2_ctrl *v4l2_ctrl_new_custom(struct v4l2_ctrl_handler *hdl,
                        const struct v4l2_ctrl_config *cfg, void *priv);

/** v4l2_ctrl_new_std() - Allocate and initialize a new standard V4L2 non-menu control.
  * @hdl:       The control handler.
  * @ops:       The control ops.
  * @id:        The control ID.
  * @min:       The control's minimum value.
  * @max:       The control's maximum value.
  * @step:      The control's step value
  * @def:       The control's default value.
  *
  * If the &v4l2_ctrl struct could not be allocated, or the control
  * ID is not known, then NULL is returned and @hdl->error is set to the
  * appropriate error code (if it wasn't set already).
  *
  * If @id refers to a menu control, then this function will return NULL.
  *
  * Use v4l2_ctrl_new_std_menu() when adding menu controls.
  */
struct v4l2_ctrl *v4l2_ctrl_new_std(struct v4l2_ctrl_handler *hdl,
                        const struct v4l2_ctrl_ops *ops,
                        u32 id, s32 min, s32 max, u32 step, s32 def);

/** v4l2_ctrl_new_std_menu() - Allocate and initialize a new standard V4L2 menu control.
  * @hdl:       The control handler.
  * @ops:       The control ops.
  * @id:        The control ID.
  * @max:       The control's maximum value.
  * @mask:      The control's skip mask for menu controls. This makes it
  *             easy to skip menu items that are not valid. If bit X is set,
  *             then menu item X is skipped. Of course, this only works for
  *             menus with <= 32 menu items. There are no menus that come
  *             close to that number, so this is OK. Should we ever need more,
  *             then this will have to be extended to a u64 or a bit array.
  * @def:       The control's default value.
  *
  * Same as v4l2_ctrl_new_std(), but @min is set to 0 and the @mask value
  * determines which menu items are to be skipped.
  *
  * If @id refers to a non-menu control, then this function will return NULL.
  */
struct v4l2_ctrl *v4l2_ctrl_new_std_menu(struct v4l2_ctrl_handler *hdl,
                        const struct v4l2_ctrl_ops *ops,
                        u32 id, s32 max, s32 mask, s32 def);

/** v4l2_ctrl_new_std_menu_items() - Create a new standard V4L2 menu control
  * with driver specific menu.
  * @hdl:       The control handler.
  * @ops:       The control ops.
  * @id:        The control ID.
  * @max:       The control's maximum value.
  * @mask:      The control's skip mask for menu controls. This makes it
  *             easy to skip menu items that are not valid. If bit X is set,
  *             then menu item X is skipped. Of course, this only works for
  *             menus with <= 32 menu items. There are no menus that come
  *             close to that number, so this is OK. Should we ever need more,
  *             then this will have to be extended to a u64 or a bit array.
  * @def:       The control's default value.
  * @qmenu:     The new menu.
  *
  * Same as v4l2_ctrl_new_std_menu(), but @qmenu will be the driver specific
  * menu of this control.
  *
  */
struct v4l2_ctrl *v4l2_ctrl_new_std_menu_items(struct v4l2_ctrl_handler *hdl,
                        const struct v4l2_ctrl_ops *ops, u32 id, s32 max,
                        s32 mask, s32 def, const char * const *qmenu);

/** v4l2_ctrl_new_int_menu() - Create a new standard V4L2 integer menu control.
  * @hdl:       The control handler.
  * @ops:       The control ops.
  * @id:        The control ID.
  * @max:       The control's maximum value.
  * @def:       The control's default value.
  * @qmenu_int: The control's menu entries.
  *
  * Same as v4l2_ctrl_new_std_menu(), but @mask is set to 0 and it additionaly
  * takes as an argument an array of integers determining the menu items.
  *
  * If @id refers to a non-integer-menu control, then this function will return NULL.
  */
struct v4l2_ctrl *v4l2_ctrl_new_int_menu(struct v4l2_ctrl_handler *hdl,
                        const struct v4l2_ctrl_ops *ops,
                        u32 id, s32 max, s32 def, const s64 *qmenu_int);

/** v4l2_ctrl_add_ctrl() - Add a control from another handler to this handler.
  * @hdl:       The control handler.
  * @ctrl:      The control to add.
  *
  * It will return NULL if it was unable to add the control reference.
  * If the control already belonged to the handler, then it will do
  * nothing and just return @ctrl.
  */
struct v4l2_ctrl *v4l2_ctrl_add_ctrl(struct v4l2_ctrl_handler *hdl,
                                          struct v4l2_ctrl *ctrl);

/** v4l2_ctrl_add_handler() - Add all controls from handler @add to
  * handler @hdl.
  * @hdl:       The control handler.
  * @add:       The control handler whose controls you want to add to
  *             the @hdl control handler.
  * @filter:    This function will filter which controls should be added.
  *
  * Does nothing if either of the two handlers is a NULL pointer.
  * If @filter is NULL, then all controls are added. Otherwise only those
  * controls for which @filter returns true will be added.
  * In case of an error @hdl->error will be set to the error code (if it
  * wasn't set already).
  */
int v4l2_ctrl_add_handler(struct v4l2_ctrl_handler *hdl,
                          struct v4l2_ctrl_handler *add,
                          bool (*filter)(const struct v4l2_ctrl *ctrl));

/** v4l2_ctrl_radio_filter() - Standard filter for radio controls.
  * @ctrl:      The control that is filtered.
  *
  * This will return true for any controls that are valid for radio device
  * nodes. Those are all of the V4L2_CID_AUDIO_* user controls and all FM
  * transmitter class controls.
  *
  * This function is to be used with v4l2_ctrl_add_handler().
  */
bool v4l2_ctrl_radio_filter(const struct v4l2_ctrl *ctrl);

/** v4l2_ctrl_cluster() - Mark all controls in the cluster as belonging to that cluster.
  * @ncontrols: The number of controls in this cluster.
  * @controls:  The cluster control array of size @ncontrols.
  */
void v4l2_ctrl_cluster(unsigned ncontrols, struct v4l2_ctrl **controls);


/** v4l2_ctrl_auto_cluster() - Mark all controls in the cluster as belonging to
  * that cluster and set it up for autofoo/foo-type handling.
  * @ncontrols: The number of controls in this cluster.
  * @controls:  The cluster control array of size @ncontrols. The first control
  *             must be the 'auto' control (e.g. autogain, autoexposure, etc.)
  * @manual_val: The value for the first control in the cluster that equals the
  *             manual setting.
  * @set_volatile: If true, then all controls except the first auto control will
  *             be volatile.
  *
  * Use for control groups where one control selects some automatic feature and
  * the other controls are only active whenever the automatic feature is turned
  * off (manual mode). Typical examples: autogain vs gain, auto-whitebalance vs
  * red and blue balance, etc.
  *
  * The behavior of such controls is as follows:
  *
  * When the autofoo control is set to automatic, then any manual controls
  * are set to inactive and any reads will call g_volatile_ctrl (if the control
  * was marked volatile).
  *
  * When the autofoo control is set to manual, then any manual controls will
  * be marked active, and any reads will just return the current value without
  * going through g_volatile_ctrl.
  *
  * In addition, this function will set the V4L2_CTRL_FLAG_UPDATE flag
  * on the autofoo control and V4L2_CTRL_FLAG_INACTIVE on the foo control(s)
  * if autofoo is in auto mode.
  */
void v4l2_ctrl_auto_cluster(unsigned ncontrols, struct v4l2_ctrl **controls,
                        u8 manual_val, bool set_volatile);


/** v4l2_ctrl_find() - Find a control with the given ID.
  * @hdl:       The control handler.
  * @id:        The control ID to find.
  *
  * If @hdl == NULL this will return NULL as well. Will lock the handler so
  * do not use from inside &v4l2_ctrl_ops.
  */
struct v4l2_ctrl *v4l2_ctrl_find(struct v4l2_ctrl_handler *hdl, u32 id);

/** v4l2_ctrl_activate() - Make the control active or inactive.
  * @ctrl:      The control to (de)activate.
  * @active:    True if the control should become active.
  *
  * This sets or clears the V4L2_CTRL_FLAG_INACTIVE flag atomically.
  * Does nothing if @ctrl == NULL.
  * This will usually be called from within the s_ctrl op.
  * The V4L2_EVENT_CTRL event will be generated afterwards.
  *
  * This function assumes that the control handler is locked.
  */
void v4l2_ctrl_activate(struct v4l2_ctrl *ctrl, bool active);

/** v4l2_ctrl_grab() - Mark the control as grabbed or not grabbed.
  * @ctrl:      The control to (de)activate.
  * @grabbed:   True if the control should become grabbed.
  *
  * This sets or clears the V4L2_CTRL_FLAG_GRABBED flag atomically.
  * Does nothing if @ctrl == NULL.
  * The V4L2_EVENT_CTRL event will be generated afterwards.
  * This will usually be called when starting or stopping streaming in the
  * driver.
  *
  * This function assumes that the control handler is not locked and will
  * take the lock itself.
  */
void v4l2_ctrl_grab(struct v4l2_ctrl *ctrl, bool grabbed);

/** v4l2_ctrl_modify_range() - Update the range of a control.
  * @ctrl:      The control to update.
  * @min:       The control's minimum value.
  * @max:       The control's maximum value.
  * @step:      The control's step value
  * @def:       The control's default value.
  *
  * Update the range of a control on the fly. This works for control types
  * INTEGER, BOOLEAN, MENU, INTEGER MENU and BITMASK. For menu controls the
  * @step value is interpreted as a menu_skip_mask.
  *
  * An error is returned if one of the range arguments is invalid for this
  * control type.
  *
  * This function assumes that the control handler is not locked and will
  * take the lock itself.
  */
int v4l2_ctrl_modify_range(struct v4l2_ctrl *ctrl,
                        s32 min, s32 max, u32 step, s32 def);

/** v4l2_ctrl_lock() - Helper function to lock the handler
  * associated with the control.
  * @ctrl:      The control to lock.
  */
static inline void v4l2_ctrl_lock(struct v4l2_ctrl *ctrl)
{
        mutex_lock(ctrl->handler->lock);
}

/** v4l2_ctrl_lock() - Helper function to unlock the handler
  * associated with the control.
  * @ctrl:      The control to unlock.
  */
static inline void v4l2_ctrl_unlock(struct v4l2_ctrl *ctrl)
{
        mutex_unlock(ctrl->handler->lock);
}

/** v4l2_ctrl_notify() - Function to set a notify callback for a control.
  * @ctrl:      The control.
  * @notify:    The callback function.
  * @priv:      The callback private handle, passed as argument to the callback.
  *
  * This function sets a callback function for the control. If @ctrl is NULL,
  * then it will do nothing. If @notify is NULL, then the notify callback will
  * be removed.
  *
  * There can be only one notify. If another already exists, then a WARN_ON
  * will be issued and the function will do nothing.
  */
void v4l2_ctrl_notify(struct v4l2_ctrl *ctrl, v4l2_ctrl_notify_fnc notify, void *priv);

/** v4l2_ctrl_g_ctrl() - Helper function to get the control's value from within a driver.
  * @ctrl:      The control.
  *
  * This returns the control's value safely by going through the control
  * framework. This function will lock the control's handler, so it cannot be
  * used from within the &v4l2_ctrl_ops functions.
  *
  * This function is for integer type controls only.
  */
s32 v4l2_ctrl_g_ctrl(struct v4l2_ctrl *ctrl);

/** v4l2_ctrl_s_ctrl() - Helper function to set the control's value from within a driver.
  * @ctrl:      The control.
  * @val:       The new value.
  *
  * This set the control's new value safely by going through the control
  * framework. This function will lock the control's handler, so it cannot be
  * used from within the &v4l2_ctrl_ops functions.
  *
  * This function is for integer type controls only.
  */
int v4l2_ctrl_s_ctrl(struct v4l2_ctrl *ctrl, s32 val);

/** v4l2_ctrl_g_ctrl_int64() - Helper function to get a 64-bit control's value from within a driver.
  * @ctrl:      The control.
  *
  * This returns the control's value safely by going through the control
  * framework. This function will lock the control's handler, so it cannot be
  * used from within the &v4l2_ctrl_ops functions.
  *
  * This function is for 64-bit integer type controls only.
  */
s64 v4l2_ctrl_g_ctrl_int64(struct v4l2_ctrl *ctrl);

/** v4l2_ctrl_s_ctrl_int64() - Helper function to set a 64-bit control's value from within a driver.
  * @ctrl:      The control.
  * @val:       The new value.
  *
  * This set the control's new value safely by going through the control
  * framework. This function will lock the control's handler, so it cannot be
  * used from within the &v4l2_ctrl_ops functions.
  *
  * This function is for 64-bit integer type controls only.
  */
int v4l2_ctrl_s_ctrl_int64(struct v4l2_ctrl *ctrl, s64 val);

/* Internal helper functions that deal with control events. */
extern const struct v4l2_subscribed_event_ops v4l2_ctrl_sub_ev_ops;
void v4l2_ctrl_replace(struct v4l2_event *old, const struct v4l2_event *new);
void v4l2_ctrl_merge(const struct v4l2_event *old, struct v4l2_event *new);

/* Can be used as a vidioc_log_status function that just dumps all controls
   associated with the filehandle. */
int v4l2_ctrl_log_status(struct file *file, void *fh);

/* Can be used as a vidioc_subscribe_event function that just subscribes
   control events. */
int v4l2_ctrl_subscribe_event(struct v4l2_fh *fh,
                                const struct v4l2_event_subscription *sub);

/* Can be used as a poll function that just polls for control events. */
unsigned int v4l2_ctrl_poll(struct file *file, struct poll_table_struct *wait);

/* Helpers for ioctl_ops. If hdl == NULL then they will all return -EINVAL. */
int v4l2_queryctrl(struct v4l2_ctrl_handler *hdl, struct v4l2_queryctrl *qc);
int v4l2_querymenu(struct v4l2_ctrl_handler *hdl, struct v4l2_querymenu *qm);
int v4l2_g_ctrl(struct v4l2_ctrl_handler *hdl, struct v4l2_control *ctrl);
int v4l2_s_ctrl(struct v4l2_fh *fh, struct v4l2_ctrl_handler *hdl,
                                                struct v4l2_control *ctrl);
int v4l2_g_ext_ctrls(struct v4l2_ctrl_handler *hdl, struct v4l2_ext_controls *c);
int v4l2_try_ext_ctrls(struct v4l2_ctrl_handler *hdl, struct v4l2_ext_controls *c);
int v4l2_s_ext_ctrls(struct v4l2_fh *fh, struct v4l2_ctrl_handler *hdl,
                                                struct v4l2_ext_controls *c);

/* Helpers for subdevices. If the associated ctrl_handler == NULL then they
   will all return -EINVAL. */
int v4l2_subdev_queryctrl(struct v4l2_subdev *sd, struct v4l2_queryctrl *qc);
int v4l2_subdev_querymenu(struct v4l2_subdev *sd, struct v4l2_querymenu *qm);
int v4l2_subdev_g_ext_ctrls(struct v4l2_subdev *sd, struct v4l2_ext_controls *cs);
int v4l2_subdev_try_ext_ctrls(struct v4l2_subdev *sd, struct v4l2_ext_controls *cs);
int v4l2_subdev_s_ext_ctrls(struct v4l2_subdev *sd, struct v4l2_ext_controls *cs);
int v4l2_subdev_g_ctrl(struct v4l2_subdev *sd, struct v4l2_control *ctrl);
int v4l2_subdev_s_ctrl(struct v4l2_subdev *sd, struct v4l2_control *ctrl);

/* Can be used as a subscribe_event function that just subscribes control
   events. */
int v4l2_ctrl_subdev_subscribe_event(struct v4l2_subdev *sd, struct v4l2_fh *fh,
                                     struct v4l2_event_subscription *sub);

/* Log all controls owned by subdev's control handler. */
int v4l2_ctrl_subdev_log_status(struct v4l2_subdev *sd);

#endif