From patchwork Wed Jul 21 14:35:28 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Laurent Pinchart X-Patchwork-Id: 113362 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by demeter.kernel.org (8.14.4/8.14.3) with ESMTP id o6LEa1CE008638 for ; Wed, 21 Jul 2010 14:36:01 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758651Ab0GUOf6 (ORCPT ); Wed, 21 Jul 2010 10:35:58 -0400 Received: from perceval.irobotique.be ([92.243.18.41]:51334 "EHLO perceval.irobotique.be" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758554Ab0GUOfk (ORCPT ); Wed, 21 Jul 2010 10:35:40 -0400 Received: from localhost.localdomain (unknown [91.178.8.228]) by perceval.irobotique.be (Postfix) with ESMTPSA id D009635D37; Wed, 21 Jul 2010 14:35:37 +0000 (UTC) From: Laurent Pinchart To: linux-media@vger.kernel.org Cc: sakari.ailus@maxwell.research.nokia.com Subject: [RFC/PATCH v2 03/10] media: Entities, pads and links Date: Wed, 21 Jul 2010 16:35:28 +0200 Message-Id: <1279722935-28493-4-git-send-email-laurent.pinchart@ideasonboard.com> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1279722935-28493-1-git-send-email-laurent.pinchart@ideasonboard.com> References: <1279722935-28493-1-git-send-email-laurent.pinchart@ideasonboard.com> Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.2.3 (demeter.kernel.org [140.211.167.41]); Wed, 21 Jul 2010 14:36:01 +0000 (UTC) diff --git a/Documentation/media-framework.txt b/Documentation/media-framework.txt index b942c8f..1c8779c 100644 --- a/Documentation/media-framework.txt +++ b/Documentation/media-framework.txt @@ -35,6 +35,30 @@ belong to userspace. The media kernel API aims at solving those problems. +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 +modeled 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 ------------ @@ -66,3 +90,106 @@ Drivers unregister media device instances by calling Unregistering a media device that hasn't been registered is *NOT* safe. + +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 entities by calling + + media_entity_init(struct media_entity *entity, u8 num_pads, + struct media_entity_pad *pads, u8 extra_links); + +The media_entity name, type and subtype fields can be initialized before or +after calling media_entity_init. Entities embedded in higher-level standard +structures have those fields set by the higher-level framework. + +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_init. The function will initialize the other pads fields. + +Unlike the number of pads, the total number of links isn't always known in +advance by the entity driver. As an initial estimate, media_entity_init +pre-allocates a number of links equal to the number of pads plus an optional +number of extra links. The links array will be reallocated if it grows beyond +the initial estimate. + +Drivers register entities with a media device by calling + + media_device_register_entity(struct media_device *mdev, + struct media_entity *entity); + +When registered the entity is assigned an ID. Entity IDs are positive integers +and are guaranteed to be unique in the context of the media device. The +framework doesn't guarantee that IDs will always be continuous. + +Drivers unregister entities by calling + + media_device_unregister_entity(struct media_entity *entity); + +Unregistering an entity will not change the IDs of the other entities, and the +ID will never be reused for a newly registered entity. + +When a media device is unregistered, all its entities are unregistered +automatically. No manual entities unregistration is then required. + +Drivers free resources associated with an entity by calling + + media_entity_cleanup(struct media_entity *entity); + +This function must be called during the cleanup phase after unregistering the +entity. Note that the media_entity instance itself must be freed explicitly by +the driver if required. + +- Pads + +Pads are represented by a struct media_entity_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_entity_pad structure, making the +media_entity_pad pointer the canonical way to store and pass link references. + +Pads have a direction, relative to the entity they belong to: + + pads of direction MEDIA_PAD_DIR_INPUT sink data, while + pads of direction MEDIA_PAD_DIR_OUTPUT source data. + +- Links + +Links are represented by a struct media_entity_link instance, defined in +include/media/media-entity.h. Each entity stores all links originating at or +targetting any of its pads in a links array. A given link is thus stored +twice, once in the source entity and once in the target entity. The array is +pre-allocated and grows dynamically as needed. + +Drivers create links by calling + + media_entity_create_link(struct media_entity *source, u8 source_pad, + struct media_entity *sink, u8 sink_pad, + u32 flags); + +An entry in the link array of each entity is allocated and stores pointers +to source and sink pads. + +Links have flags that describe the link capabilities and state. + + MEDIA_LINK_FLAG_ACTIVE indicates that the link is active and can be + used to transfer media data. When two or more links target a sink pad, + only one of them can be active at a time. + MEDIA_LINK_FLAG_IMMUTABLE indicates that the link active state can't + be modified at runtime. If MEDIA_LINK_FLAG_IMMUTABLE is set, then + MEDIA_LINK_FLAG_ACTIVE must also be set since an immutable link is + always active. + diff --git a/drivers/media/Makefile b/drivers/media/Makefile index f8d8dcb..a425581 100644 --- a/drivers/media/Makefile +++ b/drivers/media/Makefile @@ -2,7 +2,7 @@ # Makefile for the kernel multimedia device drivers. # -media-objs := media-device.o media-devnode.o +media-objs := media-device.o media-devnode.o media-entity.o obj-$(CONFIG_MEDIA_SUPPORT) += media.o diff --git a/drivers/media/media-device.c b/drivers/media/media-device.c index 871fdfa..3e16138 100644 --- a/drivers/media/media-device.c +++ b/drivers/media/media-device.c @@ -23,6 +23,7 @@ #include #include +#include static const struct media_file_operations media_device_fops = { .owner = THIS_MODULE, @@ -47,6 +48,10 @@ static void media_device_release(struct media_devnode *mdev) */ int __must_check media_device_register(struct media_device *mdev) { + mdev->entity_id = 1; + INIT_LIST_HEAD(&mdev->entities); + spin_lock_init(&mdev->lock); + /* If dev == NULL, then name must be filled in by the caller */ if (mdev->dev == NULL && WARN_ON(!mdev->name[0])) return 0; @@ -72,6 +77,54 @@ EXPORT_SYMBOL_GPL(media_device_register); */ void media_device_unregister(struct media_device *mdev) { + struct media_entity *entity; + struct media_entity *next; + + list_for_each_entry_safe(entity, next, &mdev->entities, list) + media_device_unregister_entity(entity); + media_devnode_unregister(&mdev->devnode); } EXPORT_SYMBOL_GPL(media_device_unregister); + +/** + * media_device_register_entity - Register an entity with a media device + * @mdev: The media device + * @entity: The entity + */ +int __must_check media_device_register_entity(struct media_device *mdev, + struct media_entity *entity) +{ + /* Warn if we apparently re-register an entity */ + WARN_ON(entity->parent != NULL); + entity->parent = mdev; + + spin_lock(&mdev->lock); + entity->id = mdev->entity_id++; + list_add_tail(&entity->list, &mdev->entities); + spin_unlock(&mdev->lock); + + return 0; +} +EXPORT_SYMBOL_GPL(media_device_register_entity); + +/** + * media_device_unregister_entity - Unregister an entity + * @entity: The entity + * + * If the entity has never been registered this function will return + * immediately. + */ +void media_device_unregister_entity(struct media_entity *entity) +{ + struct media_device *mdev = entity->parent; + + if (mdev == NULL) + return; + + spin_lock(&mdev->lock); + list_del(&entity->list); + spin_unlock(&mdev->lock); + entity->parent = NULL; +} +EXPORT_SYMBOL_GPL(media_device_unregister_entity); diff --git a/drivers/media/media-entity.c b/drivers/media/media-entity.c new file mode 100644 index 0000000..78c3fd2 --- /dev/null +++ b/drivers/media/media-entity.c @@ -0,0 +1,145 @@ +/* + * Media Entity support + * + * Copyright (C) 2010 Laurent Pinchart + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * 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 + */ + +#include +#include +#include + +/** + * media_entity_init - Initialize a media entity + * + * @num_pads: Total number of input and output pads. + * @extra_links: Initial estimate of the number of extra links. + * @pads: Array of 'num_pads' pads. + * + * The total number of pads is an intrinsic property of entities known by the + * entity driver, while the total number of links depends on hardware design + * and is an extrinsic property unknown to the entity driver. However, in most + * use cases the entity driver can guess the number of links which can safely + * be assumed to be equal to or larger than the number of pads. + * + * For those reasons the links array can be preallocated based on the entity + * driver guess and will be reallocated later if extra links need to be + * created. + * + * This function allocates a links array with enough space to hold at least + * 'num_pads' + 'extra_links' elements. The media_entity::max_links field will + * be set to the number of allocated elements. + * + * The pads array is managed by the entity driver and passed to + * media_entity_init() where its pointer will be stored in the entity structure. + */ +int +media_entity_init(struct media_entity *entity, u8 num_pads, + struct media_entity_pad *pads, u8 extra_links) +{ + struct media_entity_link *links; + unsigned int max_links = num_pads + extra_links; + unsigned int i; + + links = kzalloc(max_links * sizeof(links[0]), GFP_KERNEL); + if (links == NULL) + return -ENOMEM; + + entity->max_links = max_links; + entity->num_links = 0; + entity->num_backlinks = 0; + entity->num_pads = num_pads; + entity->pads = pads; + entity->links = links; + + for (i = 0; i < num_pads; i++) { + pads[i].entity = entity; + pads[i].index = i; + } + + return 0; +} +EXPORT_SYMBOL(media_entity_init); + +void +media_entity_cleanup(struct media_entity *entity) +{ + kfree(entity->links); +} +EXPORT_SYMBOL(media_entity_cleanup); + +static struct +media_entity_link *media_entity_add_link(struct media_entity *entity) +{ + if (entity->num_links >= entity->max_links) { + struct media_entity_link *links = entity->links; + unsigned int max_links = entity->max_links + 2; + unsigned int i; + + links = krealloc(links, max_links * sizeof(*links), GFP_KERNEL); + if (links == NULL) + return NULL; + + for (i = 0; i < entity->num_links; i++) + links[i].other->other = &links[i]; + + entity->max_links = max_links; + entity->links = links; + } + + return &entity->links[entity->num_links++]; +} + +int +media_entity_create_link(struct media_entity *source, u8 source_pad, + struct media_entity *sink, u8 sink_pad, u32 flags) +{ + struct media_entity_link *link; + struct media_entity_link *backlink; + + BUG_ON(source == NULL || sink == NULL); + BUG_ON(source_pad >= source->num_pads); + BUG_ON(sink_pad >= sink->num_pads); + + link = media_entity_add_link(source); + if (link == NULL) + return -ENOMEM; + + link->source = &source->pads[source_pad]; + link->sink = &sink->pads[sink_pad]; + link->flags = flags; + + /* Create the backlink. Backlinks are used to help graph traversal and + * are not reported to userspace. + */ + backlink = media_entity_add_link(sink); + if (backlink == NULL) { + source->num_links--; + return -ENOMEM; + } + + backlink->source = &source->pads[source_pad]; + backlink->sink = &sink->pads[sink_pad]; + backlink->flags = flags; + + link->other = backlink; + backlink->other = link; + + sink->num_backlinks++; + + return 0; +} +EXPORT_SYMBOL(media_entity_create_link); diff --git a/include/media/media-device.h b/include/media/media-device.h index 0bef8b3..3a713c0 100644 --- a/include/media/media-device.h +++ b/include/media/media-device.h @@ -23,8 +23,10 @@ #include #include +#include #include +#include /* Each instance of a media device should create the media_device struct, * either stand-alone or embedded in a larger struct. @@ -43,6 +45,12 @@ struct media_device { struct device *dev; struct media_devnode devnode; + u32 entity_id; + struct list_head entities; + + /* Protects the entities list */ + spinlock_t lock; + /* unique device name, by default the driver name + bus ID */ char name[MEDIA_DEVICE_NAME_SIZE]; }; @@ -50,4 +58,12 @@ struct media_device { int __must_check media_device_register(struct media_device *mdev); void media_device_unregister(struct media_device *mdev); +int __must_check media_device_register_entity(struct media_device *mdev, + struct media_entity *entity); +void media_device_unregister_entity(struct media_entity *entity); + +/* Iterate over all entities. */ +#define media_device_for_each_entity(entity, mdev) \ + list_for_each_entry(entity, &(mdev)->entities, list) + #endif diff --git a/include/media/media-entity.h b/include/media/media-entity.h new file mode 100644 index 0000000..fd44647 --- /dev/null +++ b/include/media/media-entity.h @@ -0,0 +1,79 @@ +#ifndef _MEDIA_ENTITY_H +#define _MEDIA_ENTITY_H + +#include + +#define MEDIA_ENTITY_TYPE_NODE 1 +#define MEDIA_ENTITY_TYPE_SUBDEV 2 + +#define MEDIA_ENTITY_SUBTYPE_NODE_V4L 1 +#define MEDIA_ENTITY_SUBTYPE_NODE_FB 2 +#define MEDIA_ENTITY_SUBTYPE_NODE_ALSA 3 +#define MEDIA_ENTITY_SUBTYPE_NODE_DVB 4 + +#define MEDIA_ENTITY_SUBTYPE_SUBDEV_VID_DECODER 1 +#define MEDIA_ENTITY_SUBTYPE_SUBDEV_VID_ENCODER 2 +#define MEDIA_ENTITY_SUBTYPE_SUBDEV_MISC 3 + +#define MEDIA_LINK_FLAG_ACTIVE (1 << 0) +#define MEDIA_LINK_FLAG_IMMUTABLE (1 << 1) + +#define MEDIA_PAD_DIR_INPUT 1 +#define MEDIA_PAD_DIR_OUTPUT 2 + +struct media_entity_link { + struct media_entity_pad *source;/* Source pad */ + struct media_entity_pad *sink; /* Sink pad */ + struct media_entity_link *other;/* Link in the reverse direction */ + u32 flags; /* Link flags (MEDIA_LINK_FLAG_*) */ +}; + +struct media_entity_pad { + struct media_entity *entity; /* Entity this pad belongs to */ + u32 direction; /* Pad direction (MEDIA_PAD_DIR_*) */ + u8 index; /* Pad index in the entity pads array */ +}; + +struct media_entity { + struct list_head list; + struct media_device *parent; /* Media device this entity belongs to*/ + u32 id; /* Entity ID, unique in the parent media + * device context */ + const char *name; /* Entity name */ + u32 type; /* Entity type (MEDIA_ENTITY_TYPE_*) */ + u32 subtype; /* Entity subtype (type-specific) */ + + u8 num_pads; /* Number of input and output pads */ + u8 num_links; /* Number of existing links, both active + * and inactive */ + u8 num_backlinks; /* Number of backlinks */ + u8 max_links; /* Maximum number of links */ + + struct media_entity_pad *pads; /* Array of pads (num_pads elements) */ + struct media_entity_link *links;/* Array of links (max_links elements)*/ + + union { + /* Node specifications */ + struct { + u32 major; + u32 minor; + } v4l; + struct { + u32 major; + u32 minor; + } fb; + int alsa; + int dvb; + + /* Sub-device specifications */ + /* Nothing needed yet */ + }; +}; + +int media_entity_init(struct media_entity *entity, u8 num_pads, + struct media_entity_pad *pads, u8 extra_links); +void media_entity_cleanup(struct media_entity *entity); +int media_entity_create_link(struct media_entity *source, u8 source_pad, + struct media_entity *sink, u8 sink_pad, u32 flags); + +#endif