Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1088 insertions, 0 deletions

diff --git a/include/media/media-entity.h b/include/media/media-entity.h
new file mode 100644
index 000000000..3aa3d58d1
--- /dev/null
+++ b/include/media/media-entity.h
@@ -0,0 +1,1088 @@
+/*
+ * Media entity
+ *
+ * Copyright (C) 2010 Nokia Corporation
+ *
+ * Contacts: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
+ *	     Sakari Ailus <sakari.ailus@iki.fi>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef _MEDIA_ENTITY_H
+#define _MEDIA_ENTITY_H
+
+#include <linux/bitmap.h>
+#include <linux/bug.h>
+#include <linux/fwnode.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/media.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;
+};
+
+/**
+ * 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
+ * @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;
+	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 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.
+ * @stream_count: Stream count for the entity.
+ * @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::
+ *
+ *    @stream_count and @use_count reference counts must never be
+ *    negative, but are signed integers on purpose: a simple ``WARN_ON(<0)``
+ *    check can be used to detect reference count bugs that would make them
+ *    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 stream_count;
+	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).
+ */
+#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_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
+ * 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_entity_remote_pad - Find the 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_entity_remote_pad(const struct media_pad *pad);
+
+/**
+ * media_entity_get - Get a reference to the parent module
+ *
+ * @entity: The entity
+ *
+ * Get a reference to the parent media device module.
+ *
+ * The function will return immediately if @entity is %NULL.
+ *
+ * Return: returns a pointer to the entity on success or %NULL on failure.
+ */
+struct media_entity *media_entity_get(struct media_entity *entity);
+
+/**
+ * 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
+ */
+__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_entity_put - Release the reference to the parent module
+ *
+ * @entity: The entity
+ *
+ * Release the reference count acquired by media_entity_get().
+ *
+ * The function will return immediately if @entity is %NULL.
+ */
+void media_entity_put(struct media_entity *entity);
+
+/**
+ * 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);
+struct media_link *
+
+/**
+ * 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.
+ */
+__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)
+
+#endif