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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
commit57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch)
tree5e910f0e82173f4ef4f51111366a3f1299037a7b /include/media/v4l2-ctrls.h
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diff --git a/include/media/v4l2-ctrls.h b/include/media/v4l2-ctrls.h
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+/*
+ 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/mutex.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;
+
+/** union v4l2_ctrl_ptr - A pointer to a control value.
+ * @p_s32: Pointer to a 32-bit signed value.
+ * @p_s64: Pointer to a 64-bit signed value.
+ * @p_u8: Pointer to a 8-bit unsigned value.
+ * @p_u16: Pointer to a 16-bit unsigned value.
+ * @p_u32: Pointer to a 32-bit unsigned value.
+ * @p_char: Pointer to a string.
+ * @p: Pointer to a compound value.
+ */
+union v4l2_ctrl_ptr {
+ s32 *p_s32;
+ s64 *p_s64;
+ u8 *p_u8;
+ u16 *p_u16;
+ u32 *p_u32;
+ char *p_char;
+ void *p;
+};
+
+/** 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);
+};
+
+/** struct v4l2_ctrl_type_ops - The control type operations that the driver has to provide.
+ * @equal: return true if both values are equal.
+ * @init: initialize the value.
+ * @log: log the value.
+ * @validate: validate the value. Return 0 on success and a negative value otherwise.
+ */
+struct v4l2_ctrl_type_ops {
+ bool (*equal)(const struct v4l2_ctrl *ctrl, u32 idx,
+ union v4l2_ctrl_ptr ptr1,
+ union v4l2_ctrl_ptr ptr2);
+ void (*init)(const struct v4l2_ctrl *ctrl, u32 idx,
+ union v4l2_ctrl_ptr ptr);
+ void (*log)(const struct v4l2_ctrl *ctrl);
+ int (*validate)(const struct v4l2_ctrl *ctrl, u32 idx,
+ union v4l2_ctrl_ptr ptr);
+};
+
+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.
+ * @has_changed: Set when the current value differs from the new value. Drivers
+ * should never use 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.
+ * @is_int: If set, then this control has a simple integer value (i.e. it
+ * uses ctrl->val).
+ * @is_string: If set, then this control has type V4L2_CTRL_TYPE_STRING.
+ * @is_ptr: If set, then this control is an array and/or has type >= V4L2_CTRL_COMPOUND_TYPES
+ * and/or has type V4L2_CTRL_TYPE_STRING. In other words, struct
+ * v4l2_ext_control uses field p to point to the data.
+ * @is_array: If set, then this control contains an N-dimensional array.
+ * @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.
+ * @type_ops: The control type 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.
+ * @elems: The number of elements in the N-dimensional array.
+ * @elem_size: The size in bytes of the control.
+ * @dims: The size of each dimension.
+ * @nr_of_dims:The number of dimensions in @dims.
+ * @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.
+ * @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 has_changed:1;
+ unsigned int is_private:1;
+ unsigned int is_auto:1;
+ unsigned int is_int:1;
+ unsigned int is_string:1;
+ unsigned int is_ptr:1;
+ unsigned int is_array:1;
+ unsigned int has_volatiles:1;
+ unsigned int call_notify:1;
+ unsigned int manual_mode_value:8;
+
+ const struct v4l2_ctrl_ops *ops;
+ const struct v4l2_ctrl_type_ops *type_ops;
+ u32 id;
+ const char *name;
+ enum v4l2_ctrl_type type;
+ s64 minimum, maximum, default_value;
+ u32 elems;
+ u32 elem_size;
+ u32 dims[V4L2_CTRL_MAX_DIMS];
+ u32 nr_of_dims;
+ union {
+ u64 step;
+ u64 menu_skip_mask;
+ };
+ union {
+ const char * const *qmenu;
+ const s64 *qmenu_int;
+ };
+ unsigned long flags;
+ void *priv;
+ s32 val;
+ struct {
+ s32 val;
+ } cur;
+
+ union v4l2_ctrl_ptr p_new;
+ union v4l2_ctrl_ptr p_cur;
+};
+
+/** 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.
+ * @type_ops: The control type ops. Only needed for compound controls.
+ * @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.
+ * @dims: The size of each dimension.
+ * @elem_size: The size in bytes of the control.
+ * @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 <= 64 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 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;
+ const struct v4l2_ctrl_type_ops *type_ops;
+ u32 id;
+ const char *name;
+ enum v4l2_ctrl_type type;
+ s64 min;
+ s64 max;
+ u64 step;
+ s64 def;
+ u32 dims[V4L2_CTRL_MAX_DIMS];
+ u32 elem_size;
+ u32 flags;
+ u64 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,
+ s64 *min, s64 *max, u64 *step, s64 *def, u32 *flags);
+
+
+/** v4l2_ctrl_handler_init_class() - 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.
+ * @key: Used by the lock validator if CONFIG_LOCKDEP is set.
+ * @name: Used by the lock validator if CONFIG_LOCKDEP is set.
+ *
+ * Returns an error if the buckets could not be allocated. This error will
+ * also be stored in @hdl->error.
+ *
+ * Never use this call directly, always use the v4l2_ctrl_handler_init
+ * macro that hides the @key and @name arguments.
+ */
+int v4l2_ctrl_handler_init_class(struct v4l2_ctrl_handler *hdl,
+ unsigned nr_of_controls_hint,
+ struct lock_class_key *key, const char *name);
+
+#ifdef CONFIG_LOCKDEP
+#define v4l2_ctrl_handler_init(hdl, nr_of_controls_hint) \
+( \
+ ({ \
+ static struct lock_class_key _key; \
+ v4l2_ctrl_handler_init_class(hdl, nr_of_controls_hint, \
+ &_key, \
+ KBUILD_BASENAME ":" \
+ __stringify(__LINE__) ":" \
+ "(" #hdl ")->_lock"); \
+ }) \
+)
+#else
+#define v4l2_ctrl_handler_init(hdl, nr_of_controls_hint) \
+ v4l2_ctrl_handler_init_class(hdl, nr_of_controls_hint, NULL, NULL)
+#endif
+
+/** 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_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_unlock() - 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_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, s64 min, s64 max, u64 step, s64 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 <= 64 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 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, u8 max, u64 mask, u8 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 <= 64 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 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, u8 max,
+ u64 mask, u8 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, u8 max, u8 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() - Unlocked variant of v4l2_ctrl_modify_range() */
+int __v4l2_ctrl_modify_range(struct v4l2_ctrl *ctrl,
+ s64 min, s64 max, u64 step, s64 def);
+
+/** 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.
+ */
+static inline int v4l2_ctrl_modify_range(struct v4l2_ctrl *ctrl,
+ s64 min, s64 max, u64 step, s64 def)
+{
+ int rval;
+
+ v4l2_ctrl_lock(ctrl);
+ rval = __v4l2_ctrl_modify_range(ctrl, min, max, step, def);
+ v4l2_ctrl_unlock(ctrl);
+
+ return rval;
+}
+
+/** 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_get_name() - Get the name of the control
+ * @id: The control ID.
+ *
+ * This function returns the name of the given control ID or NULL if it isn't
+ * a known control.
+ */
+const char *v4l2_ctrl_get_name(u32 id);
+
+/** v4l2_ctrl_get_menu() - Get the menu string array of the control
+ * @id: The control ID.
+ *
+ * This function returns the NULL-terminated menu string array name of the
+ * given control ID or NULL if it isn't a known menu control.
+ */
+const char * const *v4l2_ctrl_get_menu(u32 id);
+
+/** v4l2_ctrl_get_int_menu() - Get the integer menu array of the control
+ * @id: The control ID.
+ * @len: The size of the integer array.
+ *
+ * This function returns the integer array of the given control ID or NULL if it
+ * if it isn't a known integer menu control.
+ */
+const s64 *v4l2_ctrl_get_int_menu(u32 id, u32 *len);
+
+/** 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() - Unlocked variant of v4l2_ctrl_s_ctrl(). */
+int __v4l2_ctrl_s_ctrl(struct v4l2_ctrl *ctrl, s32 val);
+/** 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.
+ */
+static inline int v4l2_ctrl_s_ctrl(struct v4l2_ctrl *ctrl, s32 val)
+{
+ int rval;
+
+ v4l2_ctrl_lock(ctrl);
+ rval = __v4l2_ctrl_s_ctrl(ctrl, val);
+ v4l2_ctrl_unlock(ctrl);
+
+ return rval;
+}
+
+/** 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() - Unlocked variant of v4l2_ctrl_s_ctrl_int64(). */
+int __v4l2_ctrl_s_ctrl_int64(struct v4l2_ctrl *ctrl, s64 val);
+
+/** 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.
+ */
+static inline int v4l2_ctrl_s_ctrl_int64(struct v4l2_ctrl *ctrl, s64 val)
+{
+ int rval;
+
+ v4l2_ctrl_lock(ctrl);
+ rval = __v4l2_ctrl_s_ctrl_int64(ctrl, val);
+ v4l2_ctrl_unlock(ctrl);
+
+ return rval;
+}
+
+/** __v4l2_ctrl_s_ctrl_string() - Unlocked variant of v4l2_ctrl_s_ctrl_string(). */
+int __v4l2_ctrl_s_ctrl_string(struct v4l2_ctrl *ctrl, const char *s);
+
+/** v4l2_ctrl_s_ctrl_string() - Helper function to set a control's string value from within a driver.
+ * @ctrl: The control.
+ * @s: The new string.
+ *
+ * This set the control's new string 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 string type controls only.
+ */
+static inline int v4l2_ctrl_s_ctrl_string(struct v4l2_ctrl *ctrl, const char *s)
+{
+ int rval;
+
+ v4l2_ctrl_lock(ctrl);
+ rval = __v4l2_ctrl_s_ctrl_string(ctrl, s);
+ v4l2_ctrl_unlock(ctrl);
+
+ return rval;
+}
+
+/* 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_query_ext_ctrl(struct v4l2_ctrl_handler *hdl, struct v4l2_query_ext_ctrl *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