/*
* Media device
*
* 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifndef _MEDIA_DEVICE_H
#define _MEDIA_DEVICE_H
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>
#include <media/media-devnode.h>
#include <media/media-entity.h>
/**
* DOC: Media Controller
*
* The media controller userspace API is documented in DocBook format in
* Documentation/DocBook/media/v4l/media-controller.xml. This document focus
* on the kernel-side implementation of the media framework.
*
* * Abstract media device model:
*
* Discovering a device internal topology, and configuring it at runtime, is one
* of the goals of the media framework. To achieve this, hardware devices are
* modelled as an oriented graph of building blocks called entities connected
* through pads.
*
* An entity is a basic media hardware building block. It can correspond to
* a large variety of logical blocks such as physical hardware devices
* (CMOS sensor for instance), logical hardware devices (a building block
* in a System-on-Chip image processing pipeline), DMA channels or physical
* connectors.
*
* A pad is a connection endpoint through which an entity can interact with
* other entities. Data (not restricted to video) produced by an entity
* flows from the entity's output to one or more entity inputs. Pads should
* not be confused with physical pins at chip boundaries.
*
* A link is a point-to-point oriented connection between two pads, either
* on the same entity or on different entities. Data flows from a source
* pad to a sink pad.
*
*
* * Media device:
*
* A media device is represented by a struct &media_device instance, defined in
* include/media/media-device.h. Allocation of the structure is handled by the
* media device driver, usually by embedding the &media_device instance in a
* larger driver-specific structure.
*
* Drivers register media device instances by calling
* __media_device_register() via the macro media_device_register()
* and unregistered by calling
* media_device_unregister().
*
* * Entities, pads and links:
*
* - Entities
*
* Entities are represented by a struct &media_entity instance, defined in
* include/media/media-entity.h. The structure is usually embedded into a
* higher-level structure, such as a v4l2_subdev or video_device instance,
* although drivers can allocate entities directly.
*
* Drivers initialize entity pads by calling
* media_entity_pads_init().
*
* Drivers register entities with a media device by calling
* media_device_register_entity()
* and unregistred by calling
* media_device_unregister_entity().
*
* - Interfaces
*
* Interfaces are represented by a struct &media_interface instance, defined in
* include/media/media-entity.h. Currently, only one type of interface is
* defined: a device node. Such interfaces are represented by a struct
* &media_intf_devnode.
*
* Drivers initialize and create device node interfaces by calling
* media_devnode_create()
* and remove them by calling:
* media_devnode_remove().
*
* - Pads
*
* Pads are represented by a struct &media_pad instance, defined in
* include/media/media-entity.h. Each entity stores its pads in a pads array
* managed by the entity driver. Drivers usually embed the array in a
* driver-specific structure.
*
* Pads are identified by their entity and their 0-based index in the pads
* array.
* Both information are stored in the &media_pad structure, making the
* &media_pad pointer the canonical way to store and pass link references.
*
* Pads have flags that describe the pad capabilities and state.
*
* %MEDIA_PAD_FL_SINK indicates that the pad supports sinking data.
* %MEDIA_PAD_FL_SOURCE indicates that the pad supports sourcing data.
*
* NOTE: One and only one of %MEDIA_PAD_FL_SINK and %MEDIA_PAD_FL_SOURCE must
* be set for each pad.
*
* - Links
*
* Links are represented by a struct &media_link instance, defined in
* include/media/media-entity.h. There are two types of links:
*
* 1. pad to pad links:
*
* Associate two entities via their PADs. Each entity has a list that points
* to all links originating at or targeting any of its pads.
* A given link is thus stored twice, once in the source entity and once in
* the target entity.
*
* Drivers create pad to pad links by calling:
* media_create_pad_link() and remove with media_entity_remove_links().
*
* 2. interface to entity links:
*
* Associate one interface to a Link.
*
* Drivers create interface to entity links by calling:
* media_create_intf_link() and remove with media_remove_intf_links().
*
* NOTE:
*
* Links can only be created after having both ends already created.
*
* Links have flags that describe the link capabilities and state. The
* valid values are described at media_create_pad_link() and
* media_create_intf_link().
*
* Graph traversal:
*
* The media framework provides APIs to iterate over entities in a graph.
*
* To iterate over all entities belonging to a media device, drivers can use
* the media_device_for_each_entity macro, defined in
* include/media/media-device.h.
*
* struct media_entity *entity;
*
* media_device_for_each_entity(entity, mdev) {
* // entity will point to each entity in turn
* ...
* }
*
* Drivers might also need to iterate over all entities in a graph that can be
* reached only through enabled links starting at a given entity. The media
* framework provides a depth-first graph traversal API for that purpose.
*
* Note that graphs with cycles (whether directed or undirected) are *NOT*
* supported by the graph traversal API. To prevent infinite loops, the graph
* traversal code limits the maximum depth to MEDIA_ENTITY_ENUM_MAX_DEPTH,
* currently defined as 16.
*
* Drivers initiate a graph traversal by calling
* media_entity_graph_walk_start()
*
* The graph structure, provided by the caller, is initialized to start graph
* traversal at the given entity.
*
* Drivers can then retrieve the next entity by calling
* media_entity_graph_walk_next()
*
* When the graph traversal is complete the function will return NULL.
*
* Graph traversal can be interrupted at any moment. No cleanup function call
* is required and the graph structure can be freed normally.
*
* Helper functions can be used to find a link between two given pads, or a pad
* connected to another pad through an enabled link
* media_entity_find_link() and media_entity_remote_pad()
*
* Use count and power handling:
*
* Due to the wide differences between drivers regarding power management
* needs, the media controller does not implement power management. However,
* the &media_entity structure includes a use_count field that media drivers
* can use to track the number of users of every entity for power management
* needs.
*
* The &media_entity.@use_count field is owned by media drivers and must not be
* touched by entity drivers. Access to the field must be protected by the
* &media_device.@graph_mutex lock.
*
* Links setup:
*
* Link properties can be modified at runtime by calling
* media_entity_setup_link()
*
* Pipelines and media streams:
*
* When starting streaming, drivers must notify all entities in the pipeline to
* prevent link states from being modified during streaming by calling
* media_entity_pipeline_start().
*
* The function will mark all entities connected to the given entity through
* enabled links, either directly or indirectly, as streaming.
*
* The &media_pipeline instance pointed to by the pipe argument will be stored
* in every entity in the pipeline. Drivers should embed the &media_pipeline
* structure in higher-level pipeline structures and can then access the
* pipeline through the &media_entity pipe field.
*
* Calls to media_entity_pipeline_start() can be nested. The pipeline pointer
* must be identical for all nested calls to the function.
*
* media_entity_pipeline_start() may return an error. In that case, it will
* clean up any of the changes it did by itself.
*
* When stopping the stream, drivers must notify the entities with
* media_entity_pipeline_stop().
*
* If multiple calls to media_entity_pipeline_start() have been made the same
* number of media_entity_pipeline_stop() calls are required to stop streaming.
* The &media_entity pipe field is reset to NULL on the last nested stop call.
*
* Link configuration will fail with -%EBUSY by default if either end of the
* link is a streaming entity. Links that can be modified while streaming must
* be marked with the %MEDIA_LNK_FL_DYNAMIC flag.
*
* If other operations need to be disallowed on streaming entities (such as
* changing entities configuration parameters) drivers can explicitly check the
* media_entity stream_count field to find out if an entity is streaming. This
* operation must be done with the media_device graph_mutex held.
*
* Link validation:
*
* Link validation is performed by media_entity_pipeline_start() for any
* entity which has sink pads in the pipeline. The
* &media_entity.@link_validate() callback is used for that purpose. In
* @link_validate() callback, entity driver should check that the properties of
* the source pad of the connected entity and its own sink pad match. It is up
* to the type of the entity (and in the end, the properties of the hardware)
* what matching actually means.
*
* Subsystems should facilitate link validation by providing subsystem specific
* helper functions to provide easy access for commonly needed information, and
* in the end provide a way to use driver-specific callbacks.
*/
struct device;
/**
* struct media_device - Media device
* @dev: Parent device
* @devnode: Media device node
* @model: Device model name
* @serial: Device serial number (optional)
* @bus_info: Unique and stable device location identifier
* @hw_revision: Hardware device revision
* @driver_version: Device driver version
* @topology_version: Monotonic counter for storing the version of the graph
* topology. Should be incremented each time the topology changes.
* @entity_id: Unique ID used on the last entity registered
* @pad_id: Unique ID used on the last pad registered
* @link_id: Unique ID used on the last link registered
* @intf_devnode_id: Unique ID used on the last interface devnode registered
* @entities: List of registered entities
* @interfaces: List of registered interfaces
* @pads: List of registered pads
* @links: List of registered links
* @lock: Entities list lock
* @graph_mutex: Entities graph operation lock
* @link_notify: Link state change notification callback
*
* This structure represents an abstract high-level media device. It allows easy
* access to entities and provides basic media device-level support. The
* structure can be allocated directly or embedded in a larger structure.
*
* The parent @dev is a physical device. It must be set before registering the
* media device.
*
* @model is a descriptive model name exported through sysfs. It doesn't have to
* be unique.
*/
struct media_device {
/* dev->driver_data points to this struct. */
struct device *dev;
struct media_devnode devnode;
char model[32];
char serial[40];
char bus_info[32];
u32 hw_revision;
u32 driver_version;
u32 topology_version;
u32 entity_id;
u32 pad_id;
u32 link_id;
u32 intf_devnode_id;
struct list_head entities;
struct list_head interfaces;
struct list_head pads;
struct list_head links;
/* Protects the graph objects creation/removal */
spinlock_t lock;
/* Serializes graph operations. */
struct mutex graph_mutex;
int (*link_notify)(struct media_link *link, u32 flags,
unsigned int notification);
};
#ifdef CONFIG_MEDIA_CONTROLLER
/* Supported link_notify @notification values. */
#define MEDIA_DEV_NOTIFY_PRE_LINK_CH 0
#define MEDIA_DEV_NOTIFY_POST_LINK_CH 1
/* media_devnode to media_device */
#define to_media_device(node) container_of(node, struct media_device, devnode)
/**
* media_device_init() - Initializes a media device element
*
* @mdev: pointer to struct &media_device
*
* This function initializes the media device prior to its registration.
* The media device initialization and registration is split in two functions
* to avoid race conditions and make the media device available to user-space
* before the media graph has been completed.
*
* So drivers need to first initialize the media device, register any entity
* within the media device, create pad to pad links and then finally register
* the media device by calling media_device_register() as a final step.
*/
void media_device_init(struct media_device *mdev);
/**
* media_device_cleanup() - Cleanups a media device element
*
* @mdev: pointer to struct &media_device
*
* This function that will destroy the graph_mutex that is
* initialized in media_device_init().
*/
void media_device_cleanup(struct media_device *mdev);
/**
* __media_device_register() - Registers a media device element
*
* @mdev: pointer to struct &media_device
* @owner: should be filled with %THIS_MODULE
*
* Users, should, instead, call the media_device_register() macro.
*
* The caller is responsible for initializing the media_device structure before
* registration. The following fields must be set:
*
* - dev must point to the parent device (usually a &pci_dev, &usb_interface or
* &platform_device instance).
*
* - model must be filled with the device model name as a NUL-terminated UTF-8
* string. The device/model revision must not be stored in this field.
*
* The following fields are optional:
*
* - serial is a unique serial number stored as a NUL-terminated ASCII string.
* The field is big enough to store a GUID in text form. If the hardware
* doesn't provide a unique serial number this field must be left empty.
*
* - bus_info represents the location of the device in the system as a
* NUL-terminated ASCII string. For PCI/PCIe devices bus_info must be set to
* "PCI:" (or "PCIe:") followed by the value of pci_name(). For USB devices,
* the usb_make_path() function must be used. This field is used by
* applications to distinguish between otherwise identical devices that don't
* provide a serial number.
*
* - hw_revision is the hardware device revision in a driver-specific format.
* When possible the revision should be formatted with the KERNEL_VERSION
* macro.
*
* - driver_version is formatted with the KERNEL_VERSION macro. The version
* minor must be incremented when new features are added to the userspace API
* without breaking binary compatibility. The version major must be
* incremented when binary compatibility is broken.
*
* Notes:
*
* Upon successful registration a character device named media[0-9]+ is created.
* The device major and minor numbers are dynamic. The model name is exported as
* a sysfs attribute.
*
* Unregistering a media device that hasn't been registered is *NOT* safe.
*/
int __must_check __media_device_register(struct media_device *mdev,
struct module *owner);
#define media_device_register(mdev) __media_device_register(mdev, THIS_MODULE)
/**
* __media_device_unregister() - Unegisters a media device element
*
* @mdev: pointer to struct &media_device
*/
void media_device_unregister(struct media_device *mdev);
/**
* media_device_register_entity() - registers a media entity inside a
* previously registered media device.
*
* @mdev: pointer to struct &media_device
* @entity: pointer to struct &media_entity to be registered
*
* Entities are identified by a unique positive integer ID. The media
* controller framework will such ID automatically. IDs are not guaranteed
* to be contiguous, and the ID number can change on newer Kernel versions.
* So, neither the driver nor userspace should hardcode ID numbers to refer
* to the entities, but, instead, use the framework to find the ID, when
* needed.
*
* The media_entity name, type and flags fields should be initialized before
* calling media_device_register_entity(). Entities embedded in higher-level
* standard structures can have some of those fields set by the higher-level
* framework.
*
* If the device has pads, media_entity_pads_init() should be called before
* this function. Otherwise, the &media_entity.@pad and &media_entity.@num_pads
* should be zeroed before calling this function.
*
* Entities have flags that describe the entity capabilities and state:
*
* %MEDIA_ENT_FL_DEFAULT indicates the default entity for a given type.
* This can be used to report the default audio and video devices or the
* default camera sensor.
*
* NOTE: Drivers should set the entity function before calling this function.
* Please notice that the values %MEDIA_ENT_F_V4L2_SUBDEV_UNKNOWN and
* %MEDIA_ENT_F_UNKNOWN should not be used by the drivers.
*/
int __must_check media_device_register_entity(struct media_device *mdev,
struct media_entity *entity);
/*
* media_device_unregister_entity() - unregisters a media entity.
*
* @entity: pointer to struct &media_entity to be unregistered
*
* All links associated with the entity and all PADs are automatically
* unregistered from the media_device when this function is called.
*
* Unregistering an entity will not change the IDs of the other entities and
* the previoully used ID will never be reused for a newly registered entities.
*
* When a media device is unregistered, all its entities are unregistered
* automatically. No manual entities unregistration is then required.
*
* Note: the media_entity instance itself must be freed explicitly by
* the driver if required.
*/
void media_device_unregister_entity(struct media_entity *entity);
/**
* media_device_get_devres() - get media device as device resource
* creates if one doesn't exist
*
* @dev: pointer to struct &device.
*
* Sometimes, the media controller &media_device needs to be shared by more
* than one driver. This function adds support for that, by dynamically
* allocating the &media_device and allowing it to be obtained from the
* struct &device associated with the common device where all sub-device
* components belong. So, for example, on an USB device with multiple
* interfaces, each interface may be handled by a separate per-interface
* drivers. While each interface have its own &device, they all share a
* common &device associated with the hole USB device.
*/
struct media_device *media_device_get_devres(struct device *dev);
/**
* media_device_find_devres() - find media device as device resource
*
* @dev: pointer to struct &device.
*/
struct media_device *media_device_find_devres(struct device *dev);
/* Iterate over all entities. */
#define media_device_for_each_entity(entity, mdev) \
list_for_each_entry(entity, &(mdev)->entities, graph_obj.list)
/* Iterate over all interfaces. */
#define media_device_for_each_intf(intf, mdev) \
list_for_each_entry(intf, &(mdev)->interfaces, graph_obj.list)
/* Iterate over all pads. */
#define media_device_for_each_pad(pad, mdev) \
list_for_each_entry(pad, &(mdev)->pads, graph_obj.list)
/* Iterate over all links. */
#define media_device_for_each_link(link, mdev) \
list_for_each_entry(link, &(mdev)->links, graph_obj.list)
#else
static inline int media_device_register(struct media_device *mdev)
{
return 0;
}
static inline void media_device_unregister(struct media_device *mdev)
{
}
static inline int media_device_register_entity(struct media_device *mdev,
struct media_entity *entity)
{
return 0;
}
static inline void media_device_unregister_entity(struct media_entity *entity)
{
}
static inline struct media_device *media_device_get_devres(struct device *dev)
{
return NULL;
}
static inline struct media_device *media_device_find_devres(struct device *dev)
{
return NULL;
}
#endif /* CONFIG_MEDIA_CONTROLLER */
#endif
