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 /* SPDX-License-Identifier: GPL-2.0-only */
 /*
  * Media entity
  *
  * Copyright (C) 2010 Nokia Corporation
  *
  * Contacts: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
  *       Sakari Ailus <sakari.ailus@iki.fi>
  */
 
 #ifndef _MEDIA_ENTITY_H
 #define _MEDIA_ENTITY_H
 
 #include <linux/bitmap.h>
 #include <linux/bug.h>
 #include <linux/container_of.h>
 #include <linux/fwnode.h>
 #include <linux/list.h>
 #include <linux/media.h>
 #include <linux/types.h>
 
 /* Enums used internally at the media controller to represent graphs */
 
 /**
  * enum media_gobj_type - type of a graph object
  *
  * @MEDIA_GRAPH_ENTITY:     Identify a media entity
  * @MEDIA_GRAPH_PAD:        Identify a media pad
  * @MEDIA_GRAPH_LINK:       Identify a media link
  * @MEDIA_GRAPH_INTF_DEVNODE:   Identify a media Kernel API interface via
  *              a device node
  */
 enum media_gobj_type {
     MEDIA_GRAPH_ENTITY,
     MEDIA_GRAPH_PAD,
     MEDIA_GRAPH_LINK,
     MEDIA_GRAPH_INTF_DEVNODE,
 };
 
 #define MEDIA_BITS_PER_TYPE     8
 #define MEDIA_BITS_PER_ID       (32 - MEDIA_BITS_PER_TYPE)
 #define MEDIA_ID_MASK            GENMASK_ULL(MEDIA_BITS_PER_ID - 1, 0)
 
 /* Structs to represent the objects that belong to a media graph */
 
 /**
  * struct media_gobj - Define a graph object.
  *
  * @mdev:   Pointer to the struct &media_device that owns the object
  * @id:     Non-zero object ID identifier. The ID should be unique
  *      inside a media_device, as it is composed by
  *      %MEDIA_BITS_PER_TYPE to store the type plus
  *      %MEDIA_BITS_PER_ID to store the ID
  * @list:   List entry stored in one of the per-type mdev object lists
  *
  * All objects on the media graph should have this struct embedded
  */
 struct media_gobj {
     struct media_device *mdev;
     u32         id;
     struct list_head    list;
 };
 
 #define MEDIA_ENTITY_ENUM_MAX_DEPTH 16
 
 /**
  * struct media_entity_enum - An enumeration of media entities.
  *
  * @bmap:   Bit map in which each bit represents one entity at struct
  *      media_entity->internal_idx.
  * @idx_max:    Number of bits in bmap
  */
 struct media_entity_enum {
     unsigned long *bmap;
     int idx_max;
 };
 
 /**
  * struct media_graph - Media graph traversal state
  *
  * @stack:      Graph traversal stack; the stack contains information
  *          on the path the media entities to be walked and the
  *          links through which they were reached.
  * @stack.entity:   pointer to &struct media_entity at the graph.
  * @stack.link:     pointer to &struct list_head.
  * @ent_enum:       Visited entities
  * @top:        The top of the stack
  */
 struct media_graph {
     struct {
         struct media_entity *entity;
         struct list_head *link;
     } stack[MEDIA_ENTITY_ENUM_MAX_DEPTH];
 
     struct media_entity_enum ent_enum;
     int top;
 };
 
 /**
  * struct media_pipeline - Media pipeline related information
  *
  * @streaming_count:    Streaming start count - streaming stop count
  * @graph:      Media graph walk during pipeline start / stop
  */
 struct media_pipeline {
     int streaming_count;
     struct media_graph graph;
 };
 
 /**
  * struct media_link - A link object part of a media graph.
  *
  * @graph_obj:  Embedded structure containing the media object common data
  * @list:   Linked list associated with an entity or an interface that
  *      owns the link.
  * @gobj0:  Part of a union. Used to get the pointer for the first
  *      graph_object of the link.
  * @source: Part of a union. Used only if the first object (gobj0) is
  *      a pad. In that case, it represents the source pad.
  * @intf:   Part of a union. Used only if the first object (gobj0) is
  *      an interface.
  * @gobj1:  Part of a union. Used to get the pointer for the second
  *      graph_object of the link.
  * @sink:   Part of a union. Used only if the second object (gobj1) is
  *      a pad. In that case, it represents the sink pad.
  * @entity: Part of a union. Used only if the second object (gobj1) is
  *      an entity.
  * @reverse:    Pointer to the link for the reverse direction of a pad to pad
  *      link.
  * @flags:  Link flags, as defined in uapi/media.h (MEDIA_LNK_FL_*)
  * @is_backlink: Indicate if the link is a backlink.
  */
 struct media_link {
     struct media_gobj graph_obj;
     struct list_head list;
     union {
         struct media_gobj *gobj0;
         struct media_pad *source;
         struct media_interface *intf;
     };
     union {
         struct media_gobj *gobj1;
         struct media_pad *sink;
         struct media_entity *entity;
     };
     struct media_link *reverse;
     unsigned long flags;
     bool is_backlink;
 };
 
 /**
  * enum media_pad_signal_type - type of the signal inside a media pad
  *
  * @PAD_SIGNAL_DEFAULT:
  *  Default signal. Use this when all inputs or all outputs are
  *  uniquely identified by the pad number.
  * @PAD_SIGNAL_ANALOG:
  *  The pad contains an analog signal. It can be Radio Frequency,
  *  Intermediate Frequency, a baseband signal or sub-carriers.
  *  Tuner inputs, IF-PLL demodulators, composite and s-video signals
  *  should use it.
  * @PAD_SIGNAL_DV:
  *  Contains a digital video signal, with can be a bitstream of samples
  *  taken from an analog TV video source. On such case, it usually
  *  contains the VBI data on it.
  * @PAD_SIGNAL_AUDIO:
  *  Contains an Intermediate Frequency analog signal from an audio
  *  sub-carrier or an audio bitstream. IF signals are provided by tuners
  *  and consumed by audio AM/FM decoders. Bitstream audio is provided by
  *  an audio decoder.
  */
 enum media_pad_signal_type {
     PAD_SIGNAL_DEFAULT = 0,
     PAD_SIGNAL_ANALOG,
     PAD_SIGNAL_DV,
     PAD_SIGNAL_AUDIO,
 };
 
 /**
  * struct media_pad - A media pad graph object.
  *
  * @graph_obj:  Embedded structure containing the media object common data
  * @entity: Entity this pad belongs to
  * @index:  Pad index in the entity pads array, numbered from 0 to n
  * @sig_type:   Type of the signal inside a media pad
  * @flags:  Pad flags, as defined in
  *      :ref:`include/uapi/linux/media.h <media_header>`
  *      (seek for ``MEDIA_PAD_FL_*``)
  */
 struct media_pad {
     struct media_gobj graph_obj;    /* must be first field in struct */
     struct media_entity *entity;
     u16 index;
     enum media_pad_signal_type sig_type;
     unsigned long flags;
 };
 
 /**
  * struct media_entity_operations - Media entity operations
  * @get_fwnode_pad: Return the pad number based on a fwnode endpoint or
  *          a negative value on error. This operation can be used
  *          to map a fwnode to a media pad number. Optional.
  * @link_setup:     Notify the entity of link changes. The operation can
  *          return an error, in which case link setup will be
  *          cancelled. Optional.
  * @link_validate:  Return whether a link is valid from the entity point of
  *          view. The media_pipeline_start() function
  *          validates all links by calling this operation. Optional.
  *
  * .. note::
  *
  *    Those these callbacks are called with struct &media_device.graph_mutex
  *    mutex held.
  */
 struct media_entity_operations {
     int (*get_fwnode_pad)(struct media_entity *entity,
                   struct fwnode_endpoint *endpoint);
     int (*link_setup)(struct media_entity *entity,
               const struct media_pad *local,
               const struct media_pad *remote, u32 flags);
     int (*link_validate)(struct media_link *link);
 };
 
 /**
  * enum media_entity_type - Media entity type
  *
  * @MEDIA_ENTITY_TYPE_BASE:
  *  The entity isn't embedded in another subsystem structure.
  * @MEDIA_ENTITY_TYPE_VIDEO_DEVICE:
  *  The entity is embedded in a struct video_device instance.
  * @MEDIA_ENTITY_TYPE_V4L2_SUBDEV:
  *  The entity is embedded in a struct v4l2_subdev instance.
  *
  * Media entity objects are often not instantiated directly, but the media
  * entity structure is inherited by (through embedding) other subsystem-specific
  * structures. The media entity type identifies the type of the subclass
  * structure that implements a media entity instance.
  *
  * This allows runtime type identification of media entities and safe casting to
  * the correct object type. For instance, a media entity structure instance
  * embedded in a v4l2_subdev structure instance will have the type
  * %MEDIA_ENTITY_TYPE_V4L2_SUBDEV and can safely be cast to a &v4l2_subdev
  * structure using the container_of() macro.
  */
 enum media_entity_type {
     MEDIA_ENTITY_TYPE_BASE,
     MEDIA_ENTITY_TYPE_VIDEO_DEVICE,
     MEDIA_ENTITY_TYPE_V4L2_SUBDEV,
 };
 
 /**
  * struct media_entity - A media entity graph object.
  *
  * @graph_obj:  Embedded structure containing the media object common data.
  * @name:   Entity name.
  * @obj_type:   Type of the object that implements the media_entity.
  * @function:   Entity main function, as defined in
  *      :ref:`include/uapi/linux/media.h <media_header>`
  *      (seek for ``MEDIA_ENT_F_*``)
  * @flags:  Entity flags, as defined in
  *      :ref:`include/uapi/linux/media.h <media_header>`
  *      (seek for ``MEDIA_ENT_FL_*``)
  * @num_pads:   Number of sink and source pads.
  * @num_links:  Total number of links, forward and back, enabled and disabled.
  * @num_backlinks: Number of backlinks
  * @internal_idx: An unique internal entity specific number. The numbers are
  *      re-used if entities are unregistered or registered again.
  * @pads:   Pads array with the size defined by @num_pads.
  * @links:  List of data links.
  * @ops:    Entity operations.
  * @use_count:  Use count for the entity.
  * @pipe:   Pipeline this entity belongs to.
  * @info:   Union with devnode information.  Kept just for backward
  *      compatibility.
  * @info.dev:   Contains device major and minor info.
  * @info.dev.major: device node major, if the device is a devnode.
  * @info.dev.minor: device node minor, if the device is a devnode.
  * @major:  Devnode major number (zero if not applicable). Kept just
  *      for backward compatibility.
  * @minor:  Devnode minor number (zero if not applicable). Kept just
  *      for backward compatibility.
  *
  * .. note::
  *
  *    The @use_count reference count must never be negative, but is a signed
  *    integer on purpose: a simple ``WARN_ON(<0)`` check can be used to detect
  *    reference count bugs that would make it negative.
  */
 struct media_entity {
     struct media_gobj graph_obj;    /* must be first field in struct */
     const char *name;
     enum media_entity_type obj_type;
     u32 function;
     unsigned long flags;
 
     u16 num_pads;
     u16 num_links;
     u16 num_backlinks;
     int internal_idx;
 
     struct media_pad *pads;
     struct list_head links;
 
     const struct media_entity_operations *ops;
 
     int use_count;
 
     struct media_pipeline *pipe;
 
     union {
         struct {
             u32 major;
             u32 minor;
         } dev;
     } info;
 };
 
 /**
  * struct media_interface - A media interface graph object.
  *
  * @graph_obj:      embedded graph object
  * @links:      List of links pointing to graph entities
  * @type:       Type of the interface as defined in
  *          :ref:`include/uapi/linux/media.h <media_header>`
  *          (seek for ``MEDIA_INTF_T_*``)
  * @flags:      Interface flags as defined in
  *          :ref:`include/uapi/linux/media.h <media_header>`
  *          (seek for ``MEDIA_INTF_FL_*``)
  *
  * .. note::
  *
  *    Currently, no flags for &media_interface is defined.
  */
 struct media_interface {
     struct media_gobj       graph_obj;
     struct list_head        links;
     u32             type;
     u32             flags;
 };
 
 /**
  * struct media_intf_devnode - A media interface via a device node.
  *
  * @intf:   embedded interface object
  * @major:  Major number of a device node
  * @minor:  Minor number of a device node
  */
 struct media_intf_devnode {
     struct media_interface      intf;
 
     /* Should match the fields at media_v2_intf_devnode */
     u32             major;
     u32             minor;
 };
 
 /**
  * media_entity_id() - return the media entity graph object id
  *
  * @entity: pointer to &media_entity
  */
 static inline u32 media_entity_id(struct media_entity *entity)
 {
     return entity->graph_obj.id;
 }
 
 /**
  * media_type() - return the media object type
  *
  * @gobj:   Pointer to the struct &media_gobj graph object
  */
 static inline enum media_gobj_type media_type(struct media_gobj *gobj)
 {
     return gobj->id >> MEDIA_BITS_PER_ID;
 }
 
 /**
  * media_id() - return the media object ID
  *
  * @gobj:   Pointer to the struct &media_gobj graph object
  */
 static inline u32 media_id(struct media_gobj *gobj)
 {
     return gobj->id & MEDIA_ID_MASK;
 }
 
 /**
  * media_gobj_gen_id() - encapsulates type and ID on at the object ID
  *
  * @type:   object type as define at enum &media_gobj_type.
  * @local_id:   next ID, from struct &media_device.id.
  */
 static inline u32 media_gobj_gen_id(enum media_gobj_type type, u64 local_id)
 {
     u32 id;
 
     id = type << MEDIA_BITS_PER_ID;
     id |= local_id & MEDIA_ID_MASK;
 
     return id;
 }
 
 /**
  * is_media_entity_v4l2_video_device() - Check if the entity is a video_device
  * @entity: pointer to entity
  *
  * Return: %true if the entity is an instance of a video_device object and can
  * safely be cast to a struct video_device using the container_of() macro, or
  * %false otherwise.
  */
 static inline bool is_media_entity_v4l2_video_device(struct media_entity *entity)
 {
     return entity && entity->obj_type == MEDIA_ENTITY_TYPE_VIDEO_DEVICE;
 }
 
 /**
  * is_media_entity_v4l2_subdev() - Check if the entity is a v4l2_subdev
  * @entity: pointer to entity
  *
  * Return: %true if the entity is an instance of a &v4l2_subdev object and can
  * safely be cast to a struct &v4l2_subdev using the container_of() macro, or
  * %false otherwise.
  */
 static inline bool is_media_entity_v4l2_subdev(struct media_entity *entity)
 {
     return entity && entity->obj_type == MEDIA_ENTITY_TYPE_V4L2_SUBDEV;
 }
 
 /**
  * __media_entity_enum_init - Initialise an entity enumeration
  *
  * @ent_enum: Entity enumeration to be initialised
  * @idx_max: Maximum number of entities in the enumeration
  *
  * Return: Returns zero on success or a negative error code.
  */
 __must_check int __media_entity_enum_init(struct media_entity_enum *ent_enum,
                       int idx_max);
 
 /**
  * media_entity_enum_cleanup - Release resources of an entity enumeration
  *
  * @ent_enum: Entity enumeration to be released
  */
 void media_entity_enum_cleanup(struct media_entity_enum *ent_enum);
 
 /**
  * media_entity_enum_zero - Clear the entire enum
  *
  * @ent_enum: Entity enumeration to be cleared
  */
 static inline void media_entity_enum_zero(struct media_entity_enum *ent_enum)
 {
     bitmap_zero(ent_enum->bmap, ent_enum->idx_max);
 }
 
 /**
  * media_entity_enum_set - Mark a single entity in the enum
  *
  * @ent_enum: Entity enumeration
  * @entity: Entity to be marked
  */
 static inline void media_entity_enum_set(struct media_entity_enum *ent_enum,
                      struct media_entity *entity)
 {
     if (WARN_ON(entity->internal_idx >= ent_enum->idx_max))
         return;
 
     __set_bit(entity->internal_idx, ent_enum->bmap);
 }
 
 /**
  * media_entity_enum_clear - Unmark a single entity in the enum
  *
  * @ent_enum: Entity enumeration
  * @entity: Entity to be unmarked
  */
 static inline void media_entity_enum_clear(struct media_entity_enum *ent_enum,
                        struct media_entity *entity)
 {
     if (WARN_ON(entity->internal_idx >= ent_enum->idx_max))
         return;
 
     __clear_bit(entity->internal_idx, ent_enum->bmap);
 }
 
 /**
  * media_entity_enum_test - Test whether the entity is marked
  *
  * @ent_enum: Entity enumeration
  * @entity: Entity to be tested
  *
  * Returns %true if the entity was marked.
  */
 static inline bool media_entity_enum_test(struct media_entity_enum *ent_enum,
                       struct media_entity *entity)
 {
     if (WARN_ON(entity->internal_idx >= ent_enum->idx_max))
         return true;
 
     return test_bit(entity->internal_idx, ent_enum->bmap);
 }
 
 /**
  * media_entity_enum_test_and_set - Test whether the entity is marked,
  *  and mark it
  *
  * @ent_enum: Entity enumeration
  * @entity: Entity to be tested
  *
  * Returns %true if the entity was marked, and mark it before doing so.
  */
 static inline bool
 media_entity_enum_test_and_set(struct media_entity_enum *ent_enum,
                    struct media_entity *entity)
 {
     if (WARN_ON(entity->internal_idx >= ent_enum->idx_max))
         return true;
 
     return __test_and_set_bit(entity->internal_idx, ent_enum->bmap);
 }
 
 /**
  * media_entity_enum_empty - Test whether the entire enum is empty
  *
  * @ent_enum: Entity enumeration
  *
  * Return: %true if the entity was empty.
  */
 static inline bool media_entity_enum_empty(struct media_entity_enum *ent_enum)
 {
     return bitmap_empty(ent_enum->bmap, ent_enum->idx_max);
 }
 
 /**
  * media_entity_enum_intersects - Test whether two enums intersect
  *
  * @ent_enum1: First entity enumeration
  * @ent_enum2: Second entity enumeration
  *
  * Return: %true if entity enumerations @ent_enum1 and @ent_enum2 intersect,
  * otherwise %false.
  */
 static inline bool media_entity_enum_intersects(
     struct media_entity_enum *ent_enum1,
     struct media_entity_enum *ent_enum2)
 {
     WARN_ON(ent_enum1->idx_max != ent_enum2->idx_max);
 
     return bitmap_intersects(ent_enum1->bmap, ent_enum2->bmap,
                  min(ent_enum1->idx_max, ent_enum2->idx_max));
 }
 
 /**
  * gobj_to_entity - returns the struct &media_entity pointer from the
  *  @gobj contained on it.
  *
  * @gobj: Pointer to the struct &media_gobj graph object
  */
 #define gobj_to_entity(gobj) \
         container_of(gobj, struct media_entity, graph_obj)
 
 /**
  * gobj_to_pad - returns the struct &media_pad pointer from the
  *  @gobj contained on it.
  *
  * @gobj: Pointer to the struct &media_gobj graph object
  */
 #define gobj_to_pad(gobj) \
         container_of(gobj, struct media_pad, graph_obj)
 
 /**
  * gobj_to_link - returns the struct &media_link pointer from the
  *  @gobj contained on it.
  *
  * @gobj: Pointer to the struct &media_gobj graph object
  */
 #define gobj_to_link(gobj) \
         container_of(gobj, struct media_link, graph_obj)
 
 /**
  * gobj_to_intf - returns the struct &media_interface pointer from the
  *  @gobj contained on it.
  *
  * @gobj: Pointer to the struct &media_gobj graph object
  */
 #define gobj_to_intf(gobj) \
         container_of(gobj, struct media_interface, graph_obj)
 
 /**
  * intf_to_devnode - returns the struct media_intf_devnode pointer from the
  *  @intf contained on it.
  *
  * @intf: Pointer to struct &media_intf_devnode
  */
 #define intf_to_devnode(intf) \
         container_of(intf, struct media_intf_devnode, intf)
 
 /**
  *  media_gobj_create - Initialize a graph object
  *
  * @mdev:   Pointer to the &media_device that contains the object
  * @type:   Type of the object
  * @gobj:   Pointer to the struct &media_gobj graph object
  *
  * This routine initializes the embedded struct &media_gobj inside a
  * media graph object. It is called automatically if ``media_*_create``
  * function calls are used. However, if the object (entity, link, pad,
  * interface) is embedded on some other object, this function should be
  * called before registering the object at the media controller.
  */
 void media_gobj_create(struct media_device *mdev,
             enum media_gobj_type type,
             struct media_gobj *gobj);
 
 /**
  *  media_gobj_destroy - Stop using a graph object on a media device
  *
  * @gobj:   Pointer to the struct &media_gobj graph object
  *
  * This should be called by all routines like media_device_unregister()
  * that remove/destroy media graph objects.
  */
 void media_gobj_destroy(struct media_gobj *gobj);
 
 /**
  * media_entity_pads_init() - Initialize the entity pads
  *
  * @entity: entity where the pads belong
  * @num_pads:   total number of sink and source pads
  * @pads:   Array of @num_pads pads.
  *
  * The pads array is managed by the entity driver and passed to
  * media_entity_pads_init() where its pointer will be stored in the
  * &media_entity structure.
  *
  * If no pads are needed, drivers could either directly fill
  * &media_entity->num_pads with 0 and &media_entity->pads with %NULL or call
  * this function that will do the same.
  *
  * As the number of pads is known in advance, the pads array is not allocated
  * dynamically but is managed by the entity driver. Most drivers will embed the
  * pads array in a driver-specific structure, avoiding dynamic allocation.
  *
  * Drivers must set the direction of every pad in the pads array before calling
  * media_entity_pads_init(). The function will initialize the other pads fields.
  */
 int media_entity_pads_init(struct media_entity *entity, u16 num_pads,
               struct media_pad *pads);
 
 /**
  * media_entity_cleanup() - free resources associated with an entity
  *
  * @entity: entity where the pads belong
  *
  * This function must be called during the cleanup phase after unregistering
  * the entity (currently, it does nothing).
  *
  * Calling media_entity_cleanup() on a media_entity whose memory has been
  * zeroed but that has not been initialized with media_entity_pad_init() is
  * valid and is a no-op.
  */
 #if IS_ENABLED(CONFIG_MEDIA_CONTROLLER)
 static inline void media_entity_cleanup(struct media_entity *entity) {}
 #else
 #define media_entity_cleanup(entity) do { } while (false)
 #endif
 
 /**
  * media_get_pad_index() - retrieves a pad index from an entity
  *
  * @entity: entity where the pads belong
  * @is_sink:    true if the pad is a sink, false if it is a source
  * @sig_type:   type of signal of the pad to be search
  *
  * This helper function finds the first pad index inside an entity that
  * satisfies both @is_sink and @sig_type conditions.
  *
  * Return:
  *
  * On success, return the pad number. If the pad was not found or the media
  * entity is a NULL pointer, return -EINVAL.
  */
 int media_get_pad_index(struct media_entity *entity, bool is_sink,
             enum media_pad_signal_type sig_type);
 
 /**
  * media_create_pad_link() - creates a link between two entities.
  *
  * @source: pointer to &media_entity of the source pad.
  * @source_pad: number of the source pad in the pads array
  * @sink:   pointer to &media_entity of the sink pad.
  * @sink_pad:   number of the sink pad in the pads array.
  * @flags:  Link flags, as defined in
  *      :ref:`include/uapi/linux/media.h <media_header>`
  *      ( seek for ``MEDIA_LNK_FL_*``)
  *
  * Valid values for flags:
  *
  * %MEDIA_LNK_FL_ENABLED
  *   Indicates that the link is enabled and can be used to transfer media data.
  *   When two or more links target a sink pad, only one of them can be
  *   enabled at a time.
  *
  * %MEDIA_LNK_FL_IMMUTABLE
  *   Indicates that the link enabled state can't be modified at runtime. If
  *   %MEDIA_LNK_FL_IMMUTABLE is set, then %MEDIA_LNK_FL_ENABLED must also be
  *   set, since an immutable link is always enabled.
  *
  * .. note::
  *
  *    Before calling this function, media_entity_pads_init() and
  *    media_device_register_entity() should be called previously for both ends.
  */
 __must_check int media_create_pad_link(struct media_entity *source,
             u16 source_pad, struct media_entity *sink,
             u16 sink_pad, u32 flags);
 
 /**
  * media_create_pad_links() - creates a link between two entities.
  *
  * @mdev: Pointer to the media_device that contains the object
  * @source_function: Function of the source entities. Used only if @source is
  *  NULL.
  * @source: pointer to &media_entity of the source pad. If NULL, it will use
  *  all entities that matches the @sink_function.
  * @source_pad: number of the source pad in the pads array
  * @sink_function: Function of the sink entities. Used only if @sink is NULL.
  * @sink: pointer to &media_entity of the sink pad. If NULL, it will use
  *  all entities that matches the @sink_function.
  * @sink_pad: number of the sink pad in the pads array.
  * @flags: Link flags, as defined in include/uapi/linux/media.h.
  * @allow_both_undefined: if %true, then both @source and @sink can be NULL.
  *  In such case, it will create a crossbar between all entities that
  *  matches @source_function to all entities that matches @sink_function.
  *  If %false, it will return 0 and won't create any link if both @source
  *  and @sink are NULL.
  *
  * Valid values for flags:
  *
  * A %MEDIA_LNK_FL_ENABLED flag indicates that the link is enabled and can be
  *  used to transfer media data. If multiple links are created and this
  *  flag is passed as an argument, only the first created link will have
  *  this flag.
  *
  * A %MEDIA_LNK_FL_IMMUTABLE flag indicates that the link enabled state can't
  *  be modified at runtime. If %MEDIA_LNK_FL_IMMUTABLE is set, then
  *  %MEDIA_LNK_FL_ENABLED must also be set since an immutable link is
  *  always enabled.
  *
  * It is common for some devices to have multiple source and/or sink entities
  * of the same type that should be linked. While media_create_pad_link()
  * creates link by link, this function is meant to allow 1:n, n:1 and even
  * cross-bar (n:n) links.
  *
  * .. note::
  *
  *    Before calling this function, media_entity_pads_init() and
  *    media_device_register_entity() should be called previously for the
  *    entities to be linked.
  */
 int media_create_pad_links(const struct media_device *mdev,
                const u32 source_function,
                struct media_entity *source,
                const u16 source_pad,
                const u32 sink_function,
                struct media_entity *sink,
                const u16 sink_pad,
                u32 flags,
                const bool allow_both_undefined);
 
 void __media_entity_remove_links(struct media_entity *entity);
 
 /**
  * media_entity_remove_links() - remove all links associated with an entity
  *
  * @entity: pointer to &media_entity
  *
  * .. note::
  *
  *    This is called automatically when an entity is unregistered via
  *    media_device_register_entity().
  */
 void media_entity_remove_links(struct media_entity *entity);
 
 /**
  * __media_entity_setup_link - Configure a media link without locking
  * @link: The link being configured
  * @flags: Link configuration flags
  *
  * The bulk of link setup is handled by the two entities connected through the
  * link. This function notifies both entities of the link configuration change.
  *
  * If the link is immutable or if the current and new configuration are
  * identical, return immediately.
  *
  * The user is expected to hold link->source->parent->mutex. If not,
  * media_entity_setup_link() should be used instead.
  */
 int __media_entity_setup_link(struct media_link *link, u32 flags);
 
 /**
  * media_entity_setup_link() - changes the link flags properties in runtime
  *
  * @link:   pointer to &media_link
  * @flags:  the requested new link flags
  *
  * The only configurable property is the %MEDIA_LNK_FL_ENABLED link flag
  * to enable/disable a link. Links marked with the
  * %MEDIA_LNK_FL_IMMUTABLE link flag can not be enabled or disabled.
  *
  * When a link is enabled or disabled, the media framework calls the
  * link_setup operation for the two entities at the source and sink of the
  * link, in that order. If the second link_setup call fails, another
  * link_setup call is made on the first entity to restore the original link
  * flags.
  *
  * Media device drivers can be notified of link setup operations by setting the
  * &media_device.link_notify pointer to a callback function. If provided, the
  * notification callback will be called before enabling and after disabling
  * links.
  *
  * Entity drivers must implement the link_setup operation if any of their links
  * is non-immutable. The operation must either configure the hardware or store
  * the configuration information to be applied later.
  *
  * Link configuration must not have any side effect on other links. If an
  * enabled link at a sink pad prevents another link at the same pad from
  * being enabled, the link_setup operation must return %-EBUSY and can't
  * implicitly disable the first enabled link.
  *
  * .. note::
  *
  *    The valid values of the flags for the link is the same as described
  *    on media_create_pad_link(), for pad to pad links or the same as described
  *    on media_create_intf_link(), for interface to entity links.
  */
 int media_entity_setup_link(struct media_link *link, u32 flags);
 
 /**
  * media_entity_find_link - Find a link between two pads
  * @source: Source pad
  * @sink: Sink pad
  *
  * Return: returns a pointer to the link between the two entities. If no
  * such link exists, return %NULL.
  */
 struct media_link *media_entity_find_link(struct media_pad *source,
         struct media_pad *sink);
 
 /**
  * media_pad_remote_pad_first - Find the first pad at the remote end of a link
  * @pad: Pad at the local end of the link
  *
  * Search for a remote pad connected to the given pad by iterating over all
  * links originating or terminating at that pad until an enabled link is found.
  *
  * Return: returns a pointer to the pad at the remote end of the first found
  * enabled link, or %NULL if no enabled link has been found.
  */
 struct media_pad *media_pad_remote_pad_first(const struct media_pad *pad);
 
 /**
  * media_pad_remote_pad_unique - Find a remote pad connected to a pad
  * @pad: The pad
  *
  * Search for and return a remote pad connected to @pad through an enabled
  * link. If multiple (or no) remote pads are found, an error is returned.
  *
  * The uniqueness constraint makes this helper function suitable for entities
  * that support a single active source at a time on a given pad.
  *
  * Return: A pointer to the remote pad, or one of the following error pointers
  * if an error occurs:
  *
  * * -ENOTUNIQ - Multiple links are enabled
  * * -ENOLINK - No connected pad found
  */
 struct media_pad *media_pad_remote_pad_unique(const struct media_pad *pad);
 
 /**
  * media_entity_remote_pad_unique - Find a remote pad connected to an entity
  * @entity: The entity
  * @type: The type of pad to find (MEDIA_PAD_FL_SINK or MEDIA_PAD_FL_SOURCE)
  *
  * Search for and return a remote pad of @type connected to @entity through an
  * enabled link. If multiple (or no) remote pads match these criteria, an error
  * is returned.
  *
  * The uniqueness constraint makes this helper function suitable for entities
  * that support a single active source or sink at a time.
  *
  * Return: A pointer to the remote pad, or one of the following error pointers
  * if an error occurs:
  *
  * * -ENOTUNIQ - Multiple links are enabled
  * * -ENOLINK - No connected pad found
  */
 struct media_pad *
 media_entity_remote_pad_unique(const struct media_entity *entity,
                    unsigned int type);
 
 /**
  * media_entity_remote_source_pad_unique - Find a remote source pad connected to
  *  an entity
  * @entity: The entity
  *
  * Search for and return a remote source pad connected to @entity through an
  * enabled link. If multiple (or no) remote pads match these criteria, an error
  * is returned.
  *
  * The uniqueness constraint makes this helper function suitable for entities
  * that support a single active source at a time.
  *
  * Return: A pointer to the remote pad, or one of the following error pointers
  * if an error occurs:
  *
  * * -ENOTUNIQ - Multiple links are enabled
  * * -ENOLINK - No connected pad found
  */
 static inline struct media_pad *
 media_entity_remote_source_pad_unique(const struct media_entity *entity)
 {
     return media_entity_remote_pad_unique(entity, MEDIA_PAD_FL_SOURCE);
 }
 
 /**
  * media_entity_is_streaming - Test if an entity is part of a streaming pipeline
  * @entity: The entity
  *
  * Return: True if the entity is part of a pipeline started with the
  * media_pipeline_start() function, false otherwise.
  */
 static inline bool media_entity_is_streaming(const struct media_entity *entity)
 {
     return entity->pipe;
 }
 
 /**
  * media_entity_get_fwnode_pad - Get pad number from fwnode
  *
  * @entity: The entity
  * @fwnode: Pointer to the fwnode_handle which should be used to find the pad
  * @direction_flags: Expected direction of the pad, as defined in
  *           :ref:`include/uapi/linux/media.h <media_header>`
  *           (seek for ``MEDIA_PAD_FL_*``)
  *
  * This function can be used to resolve the media pad number from
  * a fwnode. This is useful for devices which use more complex
  * mappings of media pads.
  *
  * If the entity does not implement the get_fwnode_pad() operation
  * then this function searches the entity for the first pad that
  * matches the @direction_flags.
  *
  * Return: returns the pad number on success or a negative error code.
  */
 int media_entity_get_fwnode_pad(struct media_entity *entity,
                 struct fwnode_handle *fwnode,
                 unsigned long direction_flags);
 
 /**
  * media_graph_walk_init - Allocate resources used by graph walk.
  *
  * @graph: Media graph structure that will be used to walk the graph
  * @mdev: Pointer to the &media_device that contains the object
  *
  * The caller is required to hold the media_device graph_mutex during the graph
  * walk until the graph state is released.
  *
  * Returns zero on success or a negative error code otherwise.
  */
 __must_check int media_graph_walk_init(
     struct media_graph *graph, struct media_device *mdev);
 
 /**
  * media_graph_walk_cleanup - Release resources used by graph walk.
  *
  * @graph: Media graph structure that will be used to walk the graph
  */
 void media_graph_walk_cleanup(struct media_graph *graph);
 
 /**
  * media_graph_walk_start - Start walking the media graph at a
  *  given entity
  *
  * @graph: Media graph structure that will be used to walk the graph
  * @entity: Starting entity
  *
  * Before using this function, media_graph_walk_init() must be
  * used to allocate resources used for walking the graph. This
  * function initializes the graph traversal structure to walk the
  * entities graph starting at the given entity. The traversal
  * structure must not be modified by the caller during graph
  * traversal. After the graph walk, the resources must be released
  * using media_graph_walk_cleanup().
  */
 void media_graph_walk_start(struct media_graph *graph,
                 struct media_entity *entity);
 
 /**
  * media_graph_walk_next - Get the next entity in the graph
  * @graph: Media graph structure
  *
  * Perform a depth-first traversal of the given media entities graph.
  *
  * The graph structure must have been previously initialized with a call to
  * media_graph_walk_start().
  *
  * Return: returns the next entity in the graph or %NULL if the whole graph
  * have been traversed.
  */
 struct media_entity *media_graph_walk_next(struct media_graph *graph);
 
 /**
  * media_pipeline_start - Mark a pipeline as streaming
  * @entity: Starting entity
  * @pipe: Media pipeline to be assigned to all entities in the pipeline.
  *
  * Mark all entities connected to a given entity through enabled links, either
  * directly or indirectly, as streaming. The given pipeline object is assigned
  * to every entity in the pipeline and stored in the media_entity pipe field.
  *
  * Calls to this function can be nested, in which case the same number of
  * media_pipeline_stop() calls will be required to stop streaming. The
  * pipeline pointer must be identical for all nested calls to
  * media_pipeline_start().
  */
 __must_check int media_pipeline_start(struct media_entity *entity,
                       struct media_pipeline *pipe);
 /**
  * __media_pipeline_start - Mark a pipeline as streaming
  *
  * @entity: Starting entity
  * @pipe: Media pipeline to be assigned to all entities in the pipeline.
  *
  * ..note:: This is the non-locking version of media_pipeline_start()
  */
 __must_check int __media_pipeline_start(struct media_entity *entity,
                     struct media_pipeline *pipe);
 
 /**
  * media_pipeline_stop - Mark a pipeline as not streaming
  * @entity: Starting entity
  *
  * Mark all entities connected to a given entity through enabled links, either
  * directly or indirectly, as not streaming. The media_entity pipe field is
  * reset to %NULL.
  *
  * If multiple calls to media_pipeline_start() have been made, the same
  * number of calls to this function are required to mark the pipeline as not
  * streaming.
  */
 void media_pipeline_stop(struct media_entity *entity);
 
 /**
  * __media_pipeline_stop - Mark a pipeline as not streaming
  *
  * @entity: Starting entity
  *
  * .. note:: This is the non-locking version of media_pipeline_stop()
  */
 void __media_pipeline_stop(struct media_entity *entity);
 
 /**
  * media_devnode_create() - creates and initializes a device node interface
  *
  * @mdev:   pointer to struct &media_device
  * @type:   type of the interface, as given by
  *      :ref:`include/uapi/linux/media.h <media_header>`
  *      ( seek for ``MEDIA_INTF_T_*``) macros.
  * @flags:  Interface flags, as defined in
  *      :ref:`include/uapi/linux/media.h <media_header>`
  *      ( seek for ``MEDIA_INTF_FL_*``)
  * @major:  Device node major number.
  * @minor:  Device node minor number.
  *
  * Return: if succeeded, returns a pointer to the newly allocated
  *  &media_intf_devnode pointer.
  *
  * .. note::
  *
  *    Currently, no flags for &media_interface is defined.
  */
 struct media_intf_devnode *
 __must_check media_devnode_create(struct media_device *mdev,
                   u32 type, u32 flags,
                   u32 major, u32 minor);
 /**
  * media_devnode_remove() - removes a device node interface
  *
  * @devnode:    pointer to &media_intf_devnode to be freed.
  *
  * When a device node interface is removed, all links to it are automatically
  * removed.
  */
 void media_devnode_remove(struct media_intf_devnode *devnode);
 
 /**
  * media_create_intf_link() - creates a link between an entity and an interface
  *
  * @entity: pointer to %media_entity
  * @intf:   pointer to %media_interface
  * @flags:  Link flags, as defined in
  *      :ref:`include/uapi/linux/media.h <media_header>`
  *      ( seek for ``MEDIA_LNK_FL_*``)
  *
  *
  * Valid values for flags:
  *
  * %MEDIA_LNK_FL_ENABLED
  *   Indicates that the interface is connected to the entity hardware.
  *   That's the default value for interfaces. An interface may be disabled if
  *   the hardware is busy due to the usage of some other interface that it is
  *   currently controlling the hardware.
  *
  *   A typical example is an hybrid TV device that handle only one type of
  *   stream on a given time. So, when the digital TV is streaming,
  *   the V4L2 interfaces won't be enabled, as such device is not able to
  *   also stream analog TV or radio.
  *
  * .. note::
  *
  *    Before calling this function, media_devnode_create() should be called for
  *    the interface and media_device_register_entity() should be called for the
  *    interface that will be part of the link.
  */
 struct media_link *
 __must_check media_create_intf_link(struct media_entity *entity,
                     struct media_interface *intf,
                     u32 flags);
 /**
  * __media_remove_intf_link() - remove a single interface link
  *
  * @link:   pointer to &media_link.
  *
  * .. note:: This is an unlocked version of media_remove_intf_link()
  */
 void __media_remove_intf_link(struct media_link *link);
 
 /**
  * media_remove_intf_link() - remove a single interface link
  *
  * @link:   pointer to &media_link.
  *
  * .. note:: Prefer to use this one, instead of __media_remove_intf_link()
  */
 void media_remove_intf_link(struct media_link *link);
 
 /**
  * __media_remove_intf_links() - remove all links associated with an interface
  *
  * @intf:   pointer to &media_interface
  *
  * .. note:: This is an unlocked version of media_remove_intf_links().
  */
 void __media_remove_intf_links(struct media_interface *intf);
 
 /**
  * media_remove_intf_links() - remove all links associated with an interface
  *
  * @intf:   pointer to &media_interface
  *
  * .. note::
  *
  *   #) This is called automatically when an entity is unregistered via
  *      media_device_register_entity() and by media_devnode_remove().
  *
  *   #) Prefer to use this one, instead of __media_remove_intf_links().
  */
 void media_remove_intf_links(struct media_interface *intf);
 
 /**
  * media_entity_call - Calls a struct media_entity_operations operation on
  *  an entity
  *
  * @entity: entity where the @operation will be called
  * @operation: type of the operation. Should be the name of a member of
  *  struct &media_entity_operations.
  *
  * This helper function will check if @operation is not %NULL. On such case,
  * it will issue a call to @operation\(@entity, @args\).
  */
 
 #define media_entity_call(entity, operation, args...)           \
     (((entity)->ops && (entity)->ops->operation) ?          \
      (entity)->ops->operation((entity) , ##args) : -ENOIOCTLCMD)
 
 /**
  * media_create_ancillary_link() - create an ancillary link between two
  *                 instances of &media_entity
  *
  * @primary:    pointer to the primary &media_entity
  * @ancillary:  pointer to the ancillary &media_entity
  *
  * Create an ancillary link between two entities, indicating that they
  * represent two connected pieces of hardware that form a single logical unit.
  * A typical example is a camera lens controller being linked to the sensor that
  * it is supporting.
  *
  * The function sets both MEDIA_LNK_FL_ENABLED and MEDIA_LNK_FL_IMMUTABLE for
  * the new link.
  */
 struct media_link *
 media_create_ancillary_link(struct media_entity *primary,
                 struct media_entity *ancillary);
 
 /**
  * __media_entity_next_link() - Iterate through a &media_entity's links
  *
  * @entity: pointer to the &media_entity
  * @link:   pointer to a &media_link to hold the iterated values
  * @link_type:  one of the MEDIA_LNK_FL_LINK_TYPE flags
  *
  * Return the next link against an entity matching a specific link type. This
  * allows iteration through an entity's links whilst guaranteeing all of the
  * returned links are of the given type.
  */
 struct media_link *__media_entity_next_link(struct media_entity *entity,
                         struct media_link *link,
                         unsigned long link_type);
 
 /**
  * for_each_media_entity_data_link() - Iterate through an entity's data links
  *
  * @entity: pointer to the &media_entity
  * @link:   pointer to a &media_link to hold the iterated values
  *
  * Iterate over a &media_entity's data links
  */
 #define for_each_media_entity_data_link(entity, link)           \
     for (link = __media_entity_next_link(entity, NULL,      \
                          MEDIA_LNK_FL_DATA_LINK);   \
          link;                          \
          link = __media_entity_next_link(entity, link,      \
                          MEDIA_LNK_FL_DATA_LINK))
 
 #endif

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