Introduce the 'struct media_entity_context' type, which serves for
reference counting and introduce two new media entity operations to
allow drivers to allocate and free a media entity context.
The newly introduced type will be used as a base type for the
device context types (video_device_context and v4l2_subdevice_context)
that will be introduced in the next patches.
Signed-off-by: Jacopo Mondi <jacopo.mondi@xxxxxxxxxxxxxxxx>
---
drivers/media/mc/mc-entity.c | 46 +++++++++++++++++
include/media/media-entity.h | 99 ++++++++++++++++++++++++++++++++++++
2 files changed, 145 insertions(+)
diff --git a/drivers/media/mc/mc-entity.c b/drivers/media/mc/mc-entity.c
index 951b79ca125c..8ce72d72bc1d 100644
--- a/drivers/media/mc/mc-entity.c
+++ b/drivers/media/mc/mc-entity.c
@@ -1660,3 +1660,49 @@ struct media_link *__media_entity_next_link(struct media_entity *entity,
return NULL;
}
EXPORT_SYMBOL_GPL(__media_entity_next_link);
+
+static void media_entity_release_context(struct kref *refcount)
+{
+ struct media_entity_context *ctx =
+ container_of(refcount, struct media_entity_context, refcount);
+
+ ctx->entity->ops->destroy_context(ctx);
+}
+
+struct media_entity_context *
+media_entity_context_get(struct media_entity_context *ctx)
+{
+ if (!ctx)
+ return ERR_PTR(-EINVAL);
+
+ kref_get(&ctx->refcount);
+
+ return ctx;
+}
+EXPORT_SYMBOL_GPL(media_entity_context_get);
+
+void media_entity_context_put(struct media_entity_context *ctx)
+{
+ if (!ctx)
+ return;
+
+ kref_put(&ctx->refcount, media_entity_release_context);
+}
+EXPORT_SYMBOL_GPL(media_entity_context_put);
+
+void media_entity_init_context(struct media_entity *entity,
+ struct media_entity_context *ctx)
+{
+ if (!ctx)
+ return;
+
+ ctx->entity = entity;
+ kref_init(&ctx->refcount);
+ INIT_LIST_HEAD(&ctx->list);
+}
+EXPORT_SYMBOL_GPL(media_entity_init_context);
+
+void media_entity_cleanup_context(struct media_entity_context *ctx)
+{
+}
+EXPORT_SYMBOL_GPL(media_entity_cleanup_context);
diff --git a/include/media/media-entity.h b/include/media/media-entity.h
index 4d95893c8984..002a326de9b9 100644
--- a/include/media/media-entity.h
+++ b/include/media/media-entity.h
@@ -15,6 +15,7 @@
#include <linux/bug.h>
#include <linux/container_of.h>
#include <linux/fwnode.h>
+#include <linux/kref.h>
#include <linux/list.h>
#include <linux/media.h>
#include <linux/minmax.h>
@@ -248,6 +249,37 @@ struct media_pad {
struct media_pipeline *pipe;
};
+/**
+ * struct media_entity_context - A media entity execution context
+ * @mdev_context: The media device context this media entity is bound to.
+ * The field is initialized when the entity is bound to a media
+ * device context.
+ * @entity: The media entity this context belongs to
+ * @refcount: The kref reference counter
+ * list: The list entry to link the entity context in the media device context
+ *
+ * This type represent the 'base class' used to implement execution context for
+ * video device contexts and subdevice contexts. Those types embedds an instance
+ * of 'struct media_entity_context' as their first member, allowing the MC core
+ * to implement type polymorphism and handle video device and subdevice contexts
+ * transparently.
+ *
+ * The main function of this type is to provide reference counting for the
+ * 'dervived' device context types. The video device and subdevice core
+ * populates the 'context_release' function pointer that implement specific
+ * clean-up operations, similar to what a 'virtual destructor' would do in C++.
+ *
+ * Drivers are not expected to use this type directly, but only the MC core
+ * will.
+ */
+struct media_device_context;
+struct media_entity_context {
+ struct media_device_context *mdev_context;
+ struct media_entity *entity;
+ struct kref refcount;
+ struct list_head list;
+};
+
/**
* struct media_entity_operations - Media entity operations
* @get_fwnode_pad: Return the pad number based on a fwnode endpoint or
@@ -269,6 +301,15 @@ struct media_pad {
* media_entity_has_pad_interdep().
* Optional: If the operation isn't implemented all pads
* will be considered as interdependent.
+ * @alloc_context: Allocate a media entity context. Drivers are allowed to
+ * sub-class the entity context type by defining a driver
+ * specific type that embeds an instance of either a
+ * video_device_context or subdevice_context as first
+ * member, and allocate the size of a driver-specific type
+ * in the implementation of this operation. Returns 0 for
+ * success, or an error code < 0 otherwise.
+ * @destroy_context: Release a media entity context previously allocated by
+ * the driver.
*
* .. note::
*
@@ -284,6 +325,9 @@ struct media_entity_operations {
int (*link_validate)(struct media_link *link);
bool (*has_pad_interdep)(struct media_entity *entity, unsigned int pad0,
unsigned int pad1);
+ int (*alloc_context)(struct media_entity *entity,
+ struct media_entity_context **context);
+ void (*destroy_context)(struct media_entity_context *context);
};
/**
@@ -1452,3 +1496,58 @@ struct media_link *__media_entity_next_link(struct media_entity *entity,
MEDIA_LNK_FL_DATA_LINK))
#endif
+
+/**
+ * media_entity_context_get - Increase the media entity context reference count
+ * and return a reference to it
+ *
+ * @ctx: the media entity context
+ *
+ * Increase the media entity context reference count. The reference count
+ * is increased by the V4L2 core when:
+ *
+ * - a new context is allocated when bounding a media entity to a media device
+ * context (by kref_init())
+ * - the media pipeline the context is part of starts streaming
+ *
+ * The entity context gets automatically decreased by the V4L2 core when:
+ * - a context is unbound
+ * - the pipeline stops streaming
+ */
+struct media_entity_context *
+media_entity_context_get(struct media_entity_context *ctx);
+
+/**
+ * media_entity_context_put - Decrease the media entity context reference count
+ *
+ * @ctx: the media entity context
+ *
+ * Decrease the media entity context reference count. The reference count
+ * is decreased by the V4L2 core when:
+ * - the file handle the context is associated with is closed
+ * - the media pipeline the context is part of is stopped
+ */
+void media_entity_context_put(struct media_entity_context *ctx);
+
+/**
+ * media_entity_init_context - Initialize the media entity context
+ *
+ * @entity: the media entity this context belongs to
+ * @ctx: the media entity context
+ *
+ * Initialize the media entity context by initializing the kref reference
+ * counter. The intended caller of this function are the video device context
+ * and subdevic context initialize functions.
+ */
+void media_entity_init_context(struct media_entity *entity,
+ struct media_entity_context *ctx);
+
+/**
+ * media_entity_cleanup_context - Cleanup the media entity context
+ *
+ * @ctx: the media entity context
+ *
+ * Cleanup the media entity context. The intended caller of this function are
+ * the video device and subdevice context cleanup functions.
+ */
+void media_entity_cleanup_context(struct media_entity_context *ctx);
--
2.46.0
