2 V4L2 controls support header.
4 Copyright (C) 2010 Hans Verkuil <hverkuil@xs4all.nl>
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, write to the Free Software
18 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
24 #include <linux/list.h>
25 #include <linux/mutex.h>
26 #include <linux/videodev2.h>
28 /* forward references */
30 struct v4l2_ctrl_handler;
31 struct v4l2_ctrl_helper;
35 struct v4l2_subscribed_event;
37 struct poll_table_struct;
39 /** union v4l2_ctrl_ptr - A pointer to a control value.
40 * @p_s32: Pointer to a 32-bit signed value.
41 * @p_s64: Pointer to a 64-bit signed value.
42 * @p_char: Pointer to a string.
43 * @p: Pointer to a compound value.
52 /** struct v4l2_ctrl_ops - The control operations that the driver has to provide.
53 * @g_volatile_ctrl: Get a new value for this control. Generally only relevant
54 * for volatile (and usually read-only) controls such as a control
55 * that returns the current signal strength which changes
57 * If not set, then the currently cached value will be returned.
58 * @try_ctrl: Test whether the control's value is valid. Only relevant when
59 * the usual min/max/step checks are not sufficient.
60 * @s_ctrl: Actually set the new control value. s_ctrl is compulsory. The
61 * ctrl->handler->lock is held when these ops are called, so no
62 * one else can access controls owned by that handler.
64 struct v4l2_ctrl_ops {
65 int (*g_volatile_ctrl)(struct v4l2_ctrl *ctrl);
66 int (*try_ctrl)(struct v4l2_ctrl *ctrl);
67 int (*s_ctrl)(struct v4l2_ctrl *ctrl);
70 /** struct v4l2_ctrl_type_ops - The control type operations that the driver has to provide.
71 * @equal: return true if both values are equal.
72 * @init: initialize the value.
73 * @log: log the value.
74 * @validate: validate the value. Return 0 on success and a negative value otherwise.
76 struct v4l2_ctrl_type_ops {
77 bool (*equal)(const struct v4l2_ctrl *ctrl,
78 union v4l2_ctrl_ptr ptr1,
79 union v4l2_ctrl_ptr ptr2);
80 void (*init)(const struct v4l2_ctrl *ctrl,
81 union v4l2_ctrl_ptr ptr);
82 void (*log)(const struct v4l2_ctrl *ctrl);
83 int (*validate)(const struct v4l2_ctrl *ctrl,
84 union v4l2_ctrl_ptr ptr);
87 typedef void (*v4l2_ctrl_notify_fnc)(struct v4l2_ctrl *ctrl, void *priv);
89 /** struct v4l2_ctrl - The control structure.
90 * @node: The list node.
91 * @ev_subs: The list of control event subscriptions.
92 * @handler: The handler that owns the control.
93 * @cluster: Point to start of cluster array.
94 * @ncontrols: Number of controls in cluster array.
95 * @done: Internal flag: set for each processed control.
96 * @is_new: Set when the user specified a new value for this control. It
97 * is also set when called from v4l2_ctrl_handler_setup. Drivers
98 * should never set this flag.
99 * @has_changed: Set when the current value differs from the new value. Drivers
100 * should never use this flag.
101 * @is_private: If set, then this control is private to its handler and it
102 * will not be added to any other handlers. Drivers can set
104 * @is_auto: If set, then this control selects whether the other cluster
105 * members are in 'automatic' mode or 'manual' mode. This is
106 * used for autogain/gain type clusters. Drivers should never
107 * set this flag directly.
108 * @is_int: If set, then this control has a simple integer value (i.e. it
110 * @is_string: If set, then this control has type V4L2_CTRL_TYPE_STRING.
111 * @is_ptr: If set, then this control is an array and/or has type >= V4L2_CTRL_COMPOUND_TYPES
112 * and/or has type V4L2_CTRL_TYPE_STRING. In other words, struct
113 * v4l2_ext_control uses field p to point to the data.
114 * @has_volatiles: If set, then one or more members of the cluster are volatile.
115 * Drivers should never touch this flag.
116 * @call_notify: If set, then call the handler's notify function whenever the
117 * control's value changes.
118 * @manual_mode_value: If the is_auto flag is set, then this is the value
119 * of the auto control that determines if that control is in
120 * manual mode. So if the value of the auto control equals this
121 * value, then the whole cluster is in manual mode. Drivers should
122 * never set this flag directly.
123 * @ops: The control ops.
124 * @type_ops: The control type ops.
125 * @id: The control ID.
126 * @name: The control name.
127 * @type: The control type.
128 * @minimum: The control's minimum value.
129 * @maximum: The control's maximum value.
130 * @default_value: The control's default value.
131 * @step: The control's step value for non-menu controls.
132 * @elems: The number of elements in the N-dimensional array.
133 * @elem_size: The size in bytes of the control.
134 * @dims: The size of each dimension.
135 * @nr_of_dims:The number of dimensions in @dims.
136 * @menu_skip_mask: The control's skip mask for menu controls. This makes it
137 * easy to skip menu items that are not valid. If bit X is set,
138 * then menu item X is skipped. Of course, this only works for
139 * menus with <= 32 menu items. There are no menus that come
140 * close to that number, so this is OK. Should we ever need more,
141 * then this will have to be extended to a u64 or a bit array.
142 * @qmenu: A const char * array for all menu items. Array entries that are
143 * empty strings ("") correspond to non-existing menu items (this
144 * is in addition to the menu_skip_mask above). The last entry
146 * @flags: The control's flags.
147 * @cur: The control's current value.
148 * @val: The control's new s32 value.
149 * @val64: The control's new s64 value.
150 * @priv: The control's private pointer. For use by the driver. It is
151 * untouched by the control framework. Note that this pointer is
152 * not freed when the control is deleted. Should this be needed
153 * then a new internal bitfield can be added to tell the framework
154 * to free this pointer.
157 /* Administrative fields */
158 struct list_head node;
159 struct list_head ev_subs;
160 struct v4l2_ctrl_handler *handler;
161 struct v4l2_ctrl **cluster;
165 unsigned int is_new:1;
166 unsigned int has_changed:1;
167 unsigned int is_private:1;
168 unsigned int is_auto:1;
169 unsigned int is_int:1;
170 unsigned int is_string:1;
171 unsigned int is_ptr:1;
172 unsigned int has_volatiles:1;
173 unsigned int call_notify:1;
174 unsigned int manual_mode_value:8;
176 const struct v4l2_ctrl_ops *ops;
177 const struct v4l2_ctrl_type_ops *type_ops;
180 enum v4l2_ctrl_type type;
181 s64 minimum, maximum, default_value;
184 u32 dims[V4L2_CTRL_MAX_DIMS];
191 const char * const *qmenu;
192 const s64 *qmenu_int;
201 union v4l2_ctrl_ptr p_new;
202 union v4l2_ctrl_ptr p_cur;
205 /** struct v4l2_ctrl_ref - The control reference.
206 * @node: List node for the sorted list.
207 * @next: Single-link list node for the hash.
208 * @ctrl: The actual control information.
209 * @helper: Pointer to helper struct. Used internally in prepare_ext_ctrls().
211 * Each control handler has a list of these refs. The list_head is used to
212 * keep a sorted-by-control-ID list of all controls, while the next pointer
213 * is used to link the control in the hash's bucket.
215 struct v4l2_ctrl_ref {
216 struct list_head node;
217 struct v4l2_ctrl_ref *next;
218 struct v4l2_ctrl *ctrl;
219 struct v4l2_ctrl_helper *helper;
222 /** struct v4l2_ctrl_handler - The control handler keeps track of all the
223 * controls: both the controls owned by the handler and those inherited
224 * from other handlers.
225 * @_lock: Default for "lock".
226 * @lock: Lock to control access to this handler and its controls.
227 * May be replaced by the user right after init.
228 * @ctrls: The list of controls owned by this handler.
229 * @ctrl_refs: The list of control references.
230 * @cached: The last found control reference. It is common that the same
231 * control is needed multiple times, so this is a simple
233 * @buckets: Buckets for the hashing. Allows for quick control lookup.
234 * @notify: A notify callback that is called whenever the control changes value.
235 * Note that the handler's lock is held when the notify function
237 * @notify_priv: Passed as argument to the v4l2_ctrl notify callback.
238 * @nr_of_buckets: Total number of buckets in the array.
239 * @error: The error code of the first failed control addition.
241 struct v4l2_ctrl_handler {
244 struct list_head ctrls;
245 struct list_head ctrl_refs;
246 struct v4l2_ctrl_ref *cached;
247 struct v4l2_ctrl_ref **buckets;
248 v4l2_ctrl_notify_fnc notify;
254 /** struct v4l2_ctrl_config - Control configuration structure.
255 * @ops: The control ops.
256 * @type_ops: The control type ops. Only needed for compound controls.
257 * @id: The control ID.
258 * @name: The control name.
259 * @type: The control type.
260 * @min: The control's minimum value.
261 * @max: The control's maximum value.
262 * @step: The control's step value for non-menu controls.
263 * @def: The control's default value.
264 * @dims: The size of each dimension.
265 * @elem_size: The size in bytes of the control.
266 * @flags: The control's flags.
267 * @menu_skip_mask: The control's skip mask for menu controls. This makes it
268 * easy to skip menu items that are not valid. If bit X is set,
269 * then menu item X is skipped. Of course, this only works for
270 * menus with <= 64 menu items. There are no menus that come
271 * close to that number, so this is OK. Should we ever need more,
272 * then this will have to be extended to a bit array.
273 * @qmenu: A const char * array for all menu items. Array entries that are
274 * empty strings ("") correspond to non-existing menu items (this
275 * is in addition to the menu_skip_mask above). The last entry
277 * @is_private: If set, then this control is private to its handler and it
278 * will not be added to any other handlers.
280 struct v4l2_ctrl_config {
281 const struct v4l2_ctrl_ops *ops;
282 const struct v4l2_ctrl_type_ops *type_ops;
285 enum v4l2_ctrl_type type;
290 u32 dims[V4L2_CTRL_MAX_DIMS];
294 const char * const *qmenu;
295 const s64 *qmenu_int;
296 unsigned int is_private:1;
299 /** v4l2_ctrl_fill() - Fill in the control fields based on the control ID.
301 * This works for all standard V4L2 controls.
302 * For non-standard controls it will only fill in the given arguments
303 * and @name will be NULL.
305 * This function will overwrite the contents of @name, @type and @flags.
306 * The contents of @min, @max, @step and @def may be modified depending on
309 * Do not use in drivers! It is used internally for backwards compatibility
310 * control handling only. Once all drivers are converted to use the new
311 * control framework this function will no longer be exported.
313 void v4l2_ctrl_fill(u32 id, const char **name, enum v4l2_ctrl_type *type,
314 s64 *min, s64 *max, u64 *step, s64 *def, u32 *flags);
317 /** v4l2_ctrl_handler_init_class() - Initialize the control handler.
318 * @hdl: The control handler.
319 * @nr_of_controls_hint: A hint of how many controls this handler is
320 * expected to refer to. This is the total number, so including
321 * any inherited controls. It doesn't have to be precise, but if
322 * it is way off, then you either waste memory (too many buckets
323 * are allocated) or the control lookup becomes slower (not enough
324 * buckets are allocated, so there are more slow list lookups).
325 * It will always work, though.
326 * @key: Used by the lock validator if CONFIG_LOCKDEP is set.
327 * @name: Used by the lock validator if CONFIG_LOCKDEP is set.
329 * Returns an error if the buckets could not be allocated. This error will
330 * also be stored in @hdl->error.
332 * Never use this call directly, always use the v4l2_ctrl_handler_init
333 * macro that hides the @key and @name arguments.
335 int v4l2_ctrl_handler_init_class(struct v4l2_ctrl_handler *hdl,
336 unsigned nr_of_controls_hint,
337 struct lock_class_key *key, const char *name);
339 #ifdef CONFIG_LOCKDEP
340 #define v4l2_ctrl_handler_init(hdl, nr_of_controls_hint) \
343 static struct lock_class_key _key; \
344 v4l2_ctrl_handler_init_class(hdl, nr_of_controls_hint, \
346 KBUILD_BASENAME ":" \
347 __stringify(__LINE__) ":" \
348 "(" #hdl ")->_lock"); \
352 #define v4l2_ctrl_handler_init(hdl, nr_of_controls_hint) \
353 v4l2_ctrl_handler_init_class(hdl, nr_of_controls_hint, NULL, NULL)
356 /** v4l2_ctrl_handler_free() - Free all controls owned by the handler and free
358 * @hdl: The control handler.
360 * Does nothing if @hdl == NULL.
362 void v4l2_ctrl_handler_free(struct v4l2_ctrl_handler *hdl);
364 /** v4l2_ctrl_handler_setup() - Call the s_ctrl op for all controls belonging
365 * to the handler to initialize the hardware to the current control values.
366 * @hdl: The control handler.
368 * Button controls will be skipped, as are read-only controls.
370 * If @hdl == NULL, then this just returns 0.
372 int v4l2_ctrl_handler_setup(struct v4l2_ctrl_handler *hdl);
374 /** v4l2_ctrl_handler_log_status() - Log all controls owned by the handler.
375 * @hdl: The control handler.
376 * @prefix: The prefix to use when logging the control values. If the
377 * prefix does not end with a space, then ": " will be added
378 * after the prefix. If @prefix == NULL, then no prefix will be
381 * For use with VIDIOC_LOG_STATUS.
383 * Does nothing if @hdl == NULL.
385 void v4l2_ctrl_handler_log_status(struct v4l2_ctrl_handler *hdl,
388 /** v4l2_ctrl_new_custom() - Allocate and initialize a new custom V4L2
390 * @hdl: The control handler.
391 * @cfg: The control's configuration data.
392 * @priv: The control's driver-specific private data.
394 * If the &v4l2_ctrl struct could not be allocated then NULL is returned
395 * and @hdl->error is set to the error code (if it wasn't set already).
397 struct v4l2_ctrl *v4l2_ctrl_new_custom(struct v4l2_ctrl_handler *hdl,
398 const struct v4l2_ctrl_config *cfg, void *priv);
400 /** v4l2_ctrl_new_std() - Allocate and initialize a new standard V4L2 non-menu control.
401 * @hdl: The control handler.
402 * @ops: The control ops.
403 * @id: The control ID.
404 * @min: The control's minimum value.
405 * @max: The control's maximum value.
406 * @step: The control's step value
407 * @def: The control's default value.
409 * If the &v4l2_ctrl struct could not be allocated, or the control
410 * ID is not known, then NULL is returned and @hdl->error is set to the
411 * appropriate error code (if it wasn't set already).
413 * If @id refers to a menu control, then this function will return NULL.
415 * Use v4l2_ctrl_new_std_menu() when adding menu controls.
417 struct v4l2_ctrl *v4l2_ctrl_new_std(struct v4l2_ctrl_handler *hdl,
418 const struct v4l2_ctrl_ops *ops,
419 u32 id, s64 min, s64 max, u64 step, s64 def);
421 /** v4l2_ctrl_new_std_menu() - Allocate and initialize a new standard V4L2 menu control.
422 * @hdl: The control handler.
423 * @ops: The control ops.
424 * @id: The control ID.
425 * @max: The control's maximum value.
426 * @mask: The control's skip mask for menu controls. This makes it
427 * easy to skip menu items that are not valid. If bit X is set,
428 * then menu item X is skipped. Of course, this only works for
429 * menus with <= 64 menu items. There are no menus that come
430 * close to that number, so this is OK. Should we ever need more,
431 * then this will have to be extended to a bit array.
432 * @def: The control's default value.
434 * Same as v4l2_ctrl_new_std(), but @min is set to 0 and the @mask value
435 * determines which menu items are to be skipped.
437 * If @id refers to a non-menu control, then this function will return NULL.
439 struct v4l2_ctrl *v4l2_ctrl_new_std_menu(struct v4l2_ctrl_handler *hdl,
440 const struct v4l2_ctrl_ops *ops,
441 u32 id, u8 max, u64 mask, u8 def);
443 /** v4l2_ctrl_new_std_menu_items() - Create a new standard V4L2 menu control
444 * with driver specific menu.
445 * @hdl: The control handler.
446 * @ops: The control ops.
447 * @id: The control ID.
448 * @max: The control's maximum value.
449 * @mask: The control's skip mask for menu controls. This makes it
450 * easy to skip menu items that are not valid. If bit X is set,
451 * then menu item X is skipped. Of course, this only works for
452 * menus with <= 64 menu items. There are no menus that come
453 * close to that number, so this is OK. Should we ever need more,
454 * then this will have to be extended to a bit array.
455 * @def: The control's default value.
456 * @qmenu: The new menu.
458 * Same as v4l2_ctrl_new_std_menu(), but @qmenu will be the driver specific
459 * menu of this control.
462 struct v4l2_ctrl *v4l2_ctrl_new_std_menu_items(struct v4l2_ctrl_handler *hdl,
463 const struct v4l2_ctrl_ops *ops, u32 id, u8 max,
464 u64 mask, u8 def, const char * const *qmenu);
466 /** v4l2_ctrl_new_int_menu() - Create a new standard V4L2 integer menu control.
467 * @hdl: The control handler.
468 * @ops: The control ops.
469 * @id: The control ID.
470 * @max: The control's maximum value.
471 * @def: The control's default value.
472 * @qmenu_int: The control's menu entries.
474 * Same as v4l2_ctrl_new_std_menu(), but @mask is set to 0 and it additionaly
475 * takes as an argument an array of integers determining the menu items.
477 * If @id refers to a non-integer-menu control, then this function will return NULL.
479 struct v4l2_ctrl *v4l2_ctrl_new_int_menu(struct v4l2_ctrl_handler *hdl,
480 const struct v4l2_ctrl_ops *ops,
481 u32 id, u8 max, u8 def, const s64 *qmenu_int);
483 /** v4l2_ctrl_add_ctrl() - Add a control from another handler to this handler.
484 * @hdl: The control handler.
485 * @ctrl: The control to add.
487 * It will return NULL if it was unable to add the control reference.
488 * If the control already belonged to the handler, then it will do
489 * nothing and just return @ctrl.
491 struct v4l2_ctrl *v4l2_ctrl_add_ctrl(struct v4l2_ctrl_handler *hdl,
492 struct v4l2_ctrl *ctrl);
494 /** v4l2_ctrl_add_handler() - Add all controls from handler @add to
496 * @hdl: The control handler.
497 * @add: The control handler whose controls you want to add to
498 * the @hdl control handler.
499 * @filter: This function will filter which controls should be added.
501 * Does nothing if either of the two handlers is a NULL pointer.
502 * If @filter is NULL, then all controls are added. Otherwise only those
503 * controls for which @filter returns true will be added.
504 * In case of an error @hdl->error will be set to the error code (if it
505 * wasn't set already).
507 int v4l2_ctrl_add_handler(struct v4l2_ctrl_handler *hdl,
508 struct v4l2_ctrl_handler *add,
509 bool (*filter)(const struct v4l2_ctrl *ctrl));
511 /** v4l2_ctrl_radio_filter() - Standard filter for radio controls.
512 * @ctrl: The control that is filtered.
514 * This will return true for any controls that are valid for radio device
515 * nodes. Those are all of the V4L2_CID_AUDIO_* user controls and all FM
516 * transmitter class controls.
518 * This function is to be used with v4l2_ctrl_add_handler().
520 bool v4l2_ctrl_radio_filter(const struct v4l2_ctrl *ctrl);
522 /** v4l2_ctrl_cluster() - Mark all controls in the cluster as belonging to that cluster.
523 * @ncontrols: The number of controls in this cluster.
524 * @controls: The cluster control array of size @ncontrols.
526 void v4l2_ctrl_cluster(unsigned ncontrols, struct v4l2_ctrl **controls);
529 /** v4l2_ctrl_auto_cluster() - Mark all controls in the cluster as belonging to
530 * that cluster and set it up for autofoo/foo-type handling.
531 * @ncontrols: The number of controls in this cluster.
532 * @controls: The cluster control array of size @ncontrols. The first control
533 * must be the 'auto' control (e.g. autogain, autoexposure, etc.)
534 * @manual_val: The value for the first control in the cluster that equals the
536 * @set_volatile: If true, then all controls except the first auto control will
539 * Use for control groups where one control selects some automatic feature and
540 * the other controls are only active whenever the automatic feature is turned
541 * off (manual mode). Typical examples: autogain vs gain, auto-whitebalance vs
542 * red and blue balance, etc.
544 * The behavior of such controls is as follows:
546 * When the autofoo control is set to automatic, then any manual controls
547 * are set to inactive and any reads will call g_volatile_ctrl (if the control
548 * was marked volatile).
550 * When the autofoo control is set to manual, then any manual controls will
551 * be marked active, and any reads will just return the current value without
552 * going through g_volatile_ctrl.
554 * In addition, this function will set the V4L2_CTRL_FLAG_UPDATE flag
555 * on the autofoo control and V4L2_CTRL_FLAG_INACTIVE on the foo control(s)
556 * if autofoo is in auto mode.
558 void v4l2_ctrl_auto_cluster(unsigned ncontrols, struct v4l2_ctrl **controls,
559 u8 manual_val, bool set_volatile);
562 /** v4l2_ctrl_find() - Find a control with the given ID.
563 * @hdl: The control handler.
564 * @id: The control ID to find.
566 * If @hdl == NULL this will return NULL as well. Will lock the handler so
567 * do not use from inside &v4l2_ctrl_ops.
569 struct v4l2_ctrl *v4l2_ctrl_find(struct v4l2_ctrl_handler *hdl, u32 id);
571 /** v4l2_ctrl_activate() - Make the control active or inactive.
572 * @ctrl: The control to (de)activate.
573 * @active: True if the control should become active.
575 * This sets or clears the V4L2_CTRL_FLAG_INACTIVE flag atomically.
576 * Does nothing if @ctrl == NULL.
577 * This will usually be called from within the s_ctrl op.
578 * The V4L2_EVENT_CTRL event will be generated afterwards.
580 * This function assumes that the control handler is locked.
582 void v4l2_ctrl_activate(struct v4l2_ctrl *ctrl, bool active);
584 /** v4l2_ctrl_grab() - Mark the control as grabbed or not grabbed.
585 * @ctrl: The control to (de)activate.
586 * @grabbed: True if the control should become grabbed.
588 * This sets or clears the V4L2_CTRL_FLAG_GRABBED flag atomically.
589 * Does nothing if @ctrl == NULL.
590 * The V4L2_EVENT_CTRL event will be generated afterwards.
591 * This will usually be called when starting or stopping streaming in the
594 * This function assumes that the control handler is not locked and will
595 * take the lock itself.
597 void v4l2_ctrl_grab(struct v4l2_ctrl *ctrl, bool grabbed);
599 /** v4l2_ctrl_modify_range() - Update the range of a control.
600 * @ctrl: The control to update.
601 * @min: The control's minimum value.
602 * @max: The control's maximum value.
603 * @step: The control's step value
604 * @def: The control's default value.
606 * Update the range of a control on the fly. This works for control types
607 * INTEGER, BOOLEAN, MENU, INTEGER MENU and BITMASK. For menu controls the
608 * @step value is interpreted as a menu_skip_mask.
610 * An error is returned if one of the range arguments is invalid for this
613 * This function assumes that the control handler is not locked and will
614 * take the lock itself.
616 int v4l2_ctrl_modify_range(struct v4l2_ctrl *ctrl,
617 s64 min, s64 max, u64 step, s64 def);
619 /** v4l2_ctrl_lock() - Helper function to lock the handler
620 * associated with the control.
621 * @ctrl: The control to lock.
623 static inline void v4l2_ctrl_lock(struct v4l2_ctrl *ctrl)
625 mutex_lock(ctrl->handler->lock);
628 /** v4l2_ctrl_unlock() - Helper function to unlock the handler
629 * associated with the control.
630 * @ctrl: The control to unlock.
632 static inline void v4l2_ctrl_unlock(struct v4l2_ctrl *ctrl)
634 mutex_unlock(ctrl->handler->lock);
637 /** v4l2_ctrl_notify() - Function to set a notify callback for a control.
638 * @ctrl: The control.
639 * @notify: The callback function.
640 * @priv: The callback private handle, passed as argument to the callback.
642 * This function sets a callback function for the control. If @ctrl is NULL,
643 * then it will do nothing. If @notify is NULL, then the notify callback will
646 * There can be only one notify. If another already exists, then a WARN_ON
647 * will be issued and the function will do nothing.
649 void v4l2_ctrl_notify(struct v4l2_ctrl *ctrl, v4l2_ctrl_notify_fnc notify, void *priv);
651 /** v4l2_ctrl_g_ctrl() - Helper function to get the control's value from within a driver.
652 * @ctrl: The control.
654 * This returns the control's value safely by going through the control
655 * framework. This function will lock the control's handler, so it cannot be
656 * used from within the &v4l2_ctrl_ops functions.
658 * This function is for integer type controls only.
660 s32 v4l2_ctrl_g_ctrl(struct v4l2_ctrl *ctrl);
662 /** v4l2_ctrl_s_ctrl() - Helper function to set the control's value from within a driver.
663 * @ctrl: The control.
664 * @val: The new value.
666 * This set the control's new value safely by going through the control
667 * framework. This function will lock the control's handler, so it cannot be
668 * used from within the &v4l2_ctrl_ops functions.
670 * This function is for integer type controls only.
672 int v4l2_ctrl_s_ctrl(struct v4l2_ctrl *ctrl, s32 val);
674 /** v4l2_ctrl_g_ctrl_int64() - Helper function to get a 64-bit control's value from within a driver.
675 * @ctrl: The control.
677 * This returns the control's value safely by going through the control
678 * framework. This function will lock the control's handler, so it cannot be
679 * used from within the &v4l2_ctrl_ops functions.
681 * This function is for 64-bit integer type controls only.
683 s64 v4l2_ctrl_g_ctrl_int64(struct v4l2_ctrl *ctrl);
685 /** v4l2_ctrl_s_ctrl_int64() - Helper function to set a 64-bit control's value from within a driver.
686 * @ctrl: The control.
687 * @val: The new value.
689 * This set the control's new value safely by going through the control
690 * framework. This function will lock the control's handler, so it cannot be
691 * used from within the &v4l2_ctrl_ops functions.
693 * This function is for 64-bit integer type controls only.
695 int v4l2_ctrl_s_ctrl_int64(struct v4l2_ctrl *ctrl, s64 val);
697 /* Internal helper functions that deal with control events. */
698 extern const struct v4l2_subscribed_event_ops v4l2_ctrl_sub_ev_ops;
699 void v4l2_ctrl_replace(struct v4l2_event *old, const struct v4l2_event *new);
700 void v4l2_ctrl_merge(const struct v4l2_event *old, struct v4l2_event *new);
702 /* Can be used as a vidioc_log_status function that just dumps all controls
703 associated with the filehandle. */
704 int v4l2_ctrl_log_status(struct file *file, void *fh);
706 /* Can be used as a vidioc_subscribe_event function that just subscribes
708 int v4l2_ctrl_subscribe_event(struct v4l2_fh *fh,
709 const struct v4l2_event_subscription *sub);
711 /* Can be used as a poll function that just polls for control events. */
712 unsigned int v4l2_ctrl_poll(struct file *file, struct poll_table_struct *wait);
714 /* Helpers for ioctl_ops. If hdl == NULL then they will all return -EINVAL. */
715 int v4l2_queryctrl(struct v4l2_ctrl_handler *hdl, struct v4l2_queryctrl *qc);
716 int v4l2_query_ext_ctrl(struct v4l2_ctrl_handler *hdl, struct v4l2_query_ext_ctrl *qc);
717 int v4l2_querymenu(struct v4l2_ctrl_handler *hdl, struct v4l2_querymenu *qm);
718 int v4l2_g_ctrl(struct v4l2_ctrl_handler *hdl, struct v4l2_control *ctrl);
719 int v4l2_s_ctrl(struct v4l2_fh *fh, struct v4l2_ctrl_handler *hdl,
720 struct v4l2_control *ctrl);
721 int v4l2_g_ext_ctrls(struct v4l2_ctrl_handler *hdl, struct v4l2_ext_controls *c);
722 int v4l2_try_ext_ctrls(struct v4l2_ctrl_handler *hdl, struct v4l2_ext_controls *c);
723 int v4l2_s_ext_ctrls(struct v4l2_fh *fh, struct v4l2_ctrl_handler *hdl,
724 struct v4l2_ext_controls *c);
726 /* Helpers for subdevices. If the associated ctrl_handler == NULL then they
727 will all return -EINVAL. */
728 int v4l2_subdev_queryctrl(struct v4l2_subdev *sd, struct v4l2_queryctrl *qc);
729 int v4l2_subdev_querymenu(struct v4l2_subdev *sd, struct v4l2_querymenu *qm);
730 int v4l2_subdev_g_ext_ctrls(struct v4l2_subdev *sd, struct v4l2_ext_controls *cs);
731 int v4l2_subdev_try_ext_ctrls(struct v4l2_subdev *sd, struct v4l2_ext_controls *cs);
732 int v4l2_subdev_s_ext_ctrls(struct v4l2_subdev *sd, struct v4l2_ext_controls *cs);
733 int v4l2_subdev_g_ctrl(struct v4l2_subdev *sd, struct v4l2_control *ctrl);
734 int v4l2_subdev_s_ctrl(struct v4l2_subdev *sd, struct v4l2_control *ctrl);
736 /* Can be used as a subscribe_event function that just subscribes control
738 int v4l2_ctrl_subdev_subscribe_event(struct v4l2_subdev *sd, struct v4l2_fh *fh,
739 struct v4l2_event_subscription *sub);
741 /* Log all controls owned by subdev's control handler. */
742 int v4l2_ctrl_subdev_log_status(struct v4l2_subdev *sd);