mm: Don't pin ZERO_PAGE in pin_user_pages()

[linux-block.git] / include / media / media-entity.h

/* 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/minmax.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
 *
 * @allocated:          Media pipeline allocated and freed by the framework
 * @mdev:               The media device the pipeline is part of
 * @pads:               List of media_pipeline_pad
 * @start_count:        Media pipeline start - stop count
 */
struct media_pipeline {
        bool allocated;
        struct media_device *mdev;
        struct list_head pads;
        int start_count;
};

/**
 * struct media_pipeline_pad - A pad part of a media pipeline
 *
 * @list:               Entry in the media_pad pads list
 * @pipe:               The media_pipeline that the pad is part of
 * @pad:                The media pad
 *
 * This structure associate a pad with a media pipeline. Instances of
 * media_pipeline_pad are created by media_pipeline_start() when it builds the
 * pipeline, and stored in the &media_pad.pads list. media_pipeline_stop()
 * removes the entries from the list and deletes them.
 */
struct media_pipeline_pad {
        struct list_head list;
        struct media_pipeline *pipe;
        struct media_pad *pad;
};

/**
 * struct media_pipeline_pad_iter - Iterator for media_pipeline_for_each_pad
 *
 * @cursor: The current element
 */
struct media_pipeline_pad_iter {
        struct list_head *cursor;
};

/**
 * struct media_pipeline_entity_iter - Iterator for media_pipeline_for_each_entity
 *
 * @ent_enum: The entity enumeration tracker
 * @cursor: The current element
 */
struct media_pipeline_entity_iter {
        struct media_entity_enum ent_enum;
        struct list_head *cursor;
};

/**
 * 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_*``)
 * @pipe:       Pipeline this pad belongs to. Use media_entity_pipeline() to
 *              access this field.
 */
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;

        /*
         * The fields below are private, and should only be accessed via
         * appropriate functions.
         */
        struct media_pipeline *pipe;
};

/**
 * 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.
 * @has_pad_interdep:   Return whether two pads of the entity are
 *                      interdependent. If two pads are interdependent they are
 *                      part of the same pipeline and enabling one of the pads
 *                      means that the other pad will become "locked" and
 *                      doesn't allow configuration changes. pad0 and pad1 are
 *                      guaranteed to not both be sinks or sources. Never call
 *                      the .has_pad_interdep() operation directly, always use
 *                      media_entity_has_pad_interdep().
 *                      Optional: If the operation isn't implemented all pads
 *                      will be considered as interdependent.
 *
 * .. 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);
        bool (*has_pad_interdep)(struct media_entity *entity, unsigned int pad0,
                                 unsigned int pad1);
};

/**
 * 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.
 * @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;

        union {
                struct {
                        u32 major;
                        u32 minor;
                } dev;
        } info;
};

/**
 * media_entity_for_each_pad - Iterate on all pads in an entity
 * @entity: The entity the pads belong to
 * @iter: The iterator pad
 *
 * Iterate on all pads in a media entity.
 */
#define media_entity_for_each_pad(entity, iter)                 \
        for (iter = (entity)->pads;                             \
             iter < &(entity)->pads[(entity)->num_pads];        \
             ++iter)

/**
 * 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
 * @mdev: The related media device
 *
 * Return: zero on success or a negative error code.
 */
__must_check int media_entity_enum_init(struct media_entity_enum *ent_enum,
                                        struct media_device *mdev);

/**
 * 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_pad_is_streaming - Test if a pad is part of a streaming pipeline
 * @pad: The pad
 *
 * Return: True if the pad is part of a pipeline started with the
 * media_pipeline_start() function, false otherwise.
 */
static inline bool media_pad_is_streaming(const struct media_pad *pad)
{
        return pad->pipe;
}

/**
 * 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)
{
        struct media_pad *pad;

        media_entity_for_each_pad(entity, pad) {
                if (media_pad_is_streaming(pad))
                        return true;
        }

        return false;
}

/**
 * media_entity_pipeline - Get the media pipeline an entity is part of
 * @entity: The entity
 *
 * DEPRECATED: use media_pad_pipeline() instead.
 *
 * This function returns the media pipeline that an entity has been associated
 * with when constructing the pipeline with media_pipeline_start(). The pointer
 * remains valid until media_pipeline_stop() is called.
 *
 * In general, entities can be part of multiple pipelines, when carrying
 * multiple streams (either on different pads, or on the same pad using
 * multiplexed streams). This function is to be used only for entities that
 * do not support multiple pipelines.
 *
 * Return: The media_pipeline the entity is part of, or NULL if the entity is
 * not part of any pipeline.
 */
struct media_pipeline *media_entity_pipeline(struct media_entity *entity);

/**
 * media_pad_pipeline - Get the media pipeline a pad is part of
 * @pad: The pad
 *
 * This function returns the media pipeline that a pad has been associated
 * with when constructing the pipeline with media_pipeline_start(). The pointer
 * remains valid until media_pipeline_stop() is called.
 *
 * Return: The media_pipeline the pad is part of, or NULL if the pad is
 * not part of any pipeline.
 */
struct media_pipeline *media_pad_pipeline(struct media_pad *pad);

/**
 * 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
 *
 * This function is deprecated, use media_pipeline_for_each_pad() instead.
 *
 * 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
 *
 * This function is deprecated, use media_pipeline_for_each_pad() instead.
 */
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
 *
 * This function is deprecated, use media_pipeline_for_each_pad() instead.
 *
 * 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
 *
 * This function is deprecated, use media_pipeline_for_each_pad() instead.
 *
 * 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
 * @pad: Starting pad
 * @pipe: Media pipeline to be assigned to all pads in the pipeline.
 *
 * Mark all pads connected to a given pad through enabled links, either
 * directly or indirectly, as streaming. The given pipeline object is assigned
 * to every pad in the pipeline and stored in the media_pad 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_pad *pad,
                                      struct media_pipeline *pipe);
/**
 * __media_pipeline_start - Mark a pipeline as streaming
 *
 * @pad: Starting pad
 * @pipe: Media pipeline to be assigned to all pads in the pipeline.
 *
 * ..note:: This is the non-locking version of media_pipeline_start()
 */
__must_check int __media_pipeline_start(struct media_pad *pad,
                                        struct media_pipeline *pipe);

/**
 * media_pipeline_stop - Mark a pipeline as not streaming
 * @pad: Starting pad
 *
 * Mark all pads connected to a given pad through enabled links, either
 * directly or indirectly, as not streaming. The media_pad 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_pad *pad);

/**
 * __media_pipeline_stop - Mark a pipeline as not streaming
 *
 * @pad: Starting pad
 *
 * .. note:: This is the non-locking version of media_pipeline_stop()
 */
void __media_pipeline_stop(struct media_pad *pad);

struct media_pad *
__media_pipeline_pad_iter_next(struct media_pipeline *pipe,
                               struct media_pipeline_pad_iter *iter,
                               struct media_pad *pad);

/**
 * media_pipeline_for_each_pad - Iterate on all pads in a media pipeline
 * @pipe: The pipeline
 * @iter: The iterator (struct media_pipeline_pad_iter)
 * @pad: The iterator pad
 *
 * Iterate on all pads in a media pipeline. This is only valid after the
 * pipeline has been built with media_pipeline_start() and before it gets
 * destroyed with media_pipeline_stop().
 */
#define media_pipeline_for_each_pad(pipe, iter, pad)                    \
        for (pad = __media_pipeline_pad_iter_next((pipe), iter, NULL);  \
             pad != NULL;                                               \
             pad = __media_pipeline_pad_iter_next((pipe), iter, pad))

/**
 * media_pipeline_entity_iter_init - Initialize a pipeline entity iterator
 * @pipe: The pipeline
 * @iter: The iterator
 *
 * This function must be called to initialize the iterator before using it in a
 * media_pipeline_for_each_entity() loop. The iterator must be destroyed by a
 * call to media_pipeline_entity_iter_cleanup after the loop (including in code
 * paths that break from the loop).
 *
 * The same iterator can be used in multiple consecutive loops without being
 * destroyed and reinitialized.
 *
 * Return: 0 on success or a negative error code otherwise.
 */
int media_pipeline_entity_iter_init(struct media_pipeline *pipe,
                                    struct media_pipeline_entity_iter *iter);

/**
 * media_pipeline_entity_iter_cleanup - Destroy a pipeline entity iterator
 * @iter: The iterator
 *
 * This function must be called to destroy iterators initialized with
 * media_pipeline_entity_iter_init().
 */
void media_pipeline_entity_iter_cleanup(struct media_pipeline_entity_iter *iter);

struct media_entity *
__media_pipeline_entity_iter_next(struct media_pipeline *pipe,
                                  struct media_pipeline_entity_iter *iter,
                                  struct media_entity *entity);

/**
 * media_pipeline_for_each_entity - Iterate on all entities in a media pipeline
 * @pipe: The pipeline
 * @iter: The iterator (struct media_pipeline_entity_iter)
 * @entity: The iterator entity
 *
 * Iterate on all entities in a media pipeline. This is only valid after the
 * pipeline has been built with media_pipeline_start() and before it gets
 * destroyed with media_pipeline_stop(). The iterator must be initialized with
 * media_pipeline_entity_iter_init() before iteration, and destroyed with
 * media_pipeline_entity_iter_cleanup() after (including in code paths that
 * break from the loop).
 */
#define media_pipeline_for_each_entity(pipe, iter, entity)                      \
        for (entity = __media_pipeline_entity_iter_next((pipe), iter, NULL);    \
             entity != NULL;                                                    \
             entity = __media_pipeline_entity_iter_next((pipe), iter, entity))

/**
 * media_pipeline_alloc_start - Mark a pipeline as streaming
 * @pad: Starting pad
 *
 * media_pipeline_alloc_start() is similar to media_pipeline_start() but instead
 * of working on a given pipeline the function will use an existing pipeline if
 * the pad is already part of a pipeline, or allocate a new pipeline.
 *
 * Calls to media_pipeline_alloc_start() must be matched with
 * media_pipeline_stop().
 */
__must_check int media_pipeline_alloc_start(struct media_pad *pad);

/**
 * 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