A memory-to-memory pipeline device consists in three
entities: two DMA engine and one video processing entities.
The DMA engine entities are linked to a V4L interface.

This commit add a new v4l2_m2m_{un}register_media_controller
API to register this topology.

For instance, a typical mem2mem device topology would
look like this:

Device topology
- entity 1: source (1 pad, 1 link)
            type Node subtype V4L flags 0
        pad0: Source
                <- "proc":0 [ENABLED,IMMUTABLE]

- entity 3: proc (2 pads, 2 links)
            type Node subtype Unknown flags 0
        pad0: Source
                -> "source":0 [ENABLED,IMMUTABLE]
        pad1: Sink
                <- "sink":0 [ENABLED,IMMUTABLE]

- entity 6: sink (1 pad, 1 link)
            type Node subtype V4L flags 0
        pad0: Sink
                -> "proc":1 [ENABLED,IMMUTABLE]

Suggested-by: Laurent Pinchart <laurent.pinch...@ideasonboard.com>
Suggested-by: Hans Verkuil <hans.verk...@cisco.com>
Signed-off-by: Ezequiel Garcia <ezequ...@collabora.com>
---
 drivers/media/v4l2-core/v4l2-dev.c     |  13 +-
 drivers/media/v4l2-core/v4l2-mem2mem.c | 176 +++++++++++++++++++++++++
 include/media/v4l2-mem2mem.h           |   5 +
 include/uapi/linux/media.h             |   3 +
 4 files changed, 192 insertions(+), 5 deletions(-)

diff --git a/drivers/media/v4l2-core/v4l2-dev.c 
b/drivers/media/v4l2-core/v4l2-dev.c
index 4ffd7d60a901..c1996d73ca74 100644
--- a/drivers/media/v4l2-core/v4l2-dev.c
+++ b/drivers/media/v4l2-core/v4l2-dev.c
@@ -202,7 +202,7 @@ static void v4l2_device_release(struct device *cd)
        mutex_unlock(&videodev_lock);
 
 #if defined(CONFIG_MEDIA_CONTROLLER)
-       if (v4l2_dev->mdev) {
+       if (v4l2_dev->mdev && vdev->vfl_dir != VFL_DIR_M2M) {
                /* Remove interfaces and interface links */
                media_devnode_remove(vdev->intf_devnode);
                if (vdev->entity.function != MEDIA_ENT_F_UNKNOWN)
@@ -733,19 +733,22 @@ static void determine_valid_ioctls(struct video_device 
*vdev)
                        BASE_VIDIOC_PRIVATE);
 }
 
-static int video_register_media_controller(struct video_device *vdev, int type)
+static int video_register_media_controller(struct video_device *vdev)
 {
 #if defined(CONFIG_MEDIA_CONTROLLER)
        u32 intf_type;
        int ret;
 
-       if (!vdev->v4l2_dev->mdev)
+       /* Memory-to-memory devices are more complex and use
+        * their own function to register its mc entities.
+        */
+       if (!vdev->v4l2_dev->mdev || vdev->vfl_dir == VFL_DIR_M2M)
                return 0;
 
        vdev->entity.obj_type = MEDIA_ENTITY_TYPE_VIDEO_DEVICE;
        vdev->entity.function = MEDIA_ENT_F_UNKNOWN;
 
-       switch (type) {
+       switch (vdev->vfl_type) {
        case VFL_TYPE_GRABBER:
                intf_type = MEDIA_INTF_T_V4L_VIDEO;
                vdev->entity.function = MEDIA_ENT_F_IO_V4L;
@@ -993,7 +996,7 @@ int __video_register_device(struct video_device *vdev,
        v4l2_device_get(vdev->v4l2_dev);
 
        /* Part 5: Register the entity. */
-       ret = video_register_media_controller(vdev, type);
+       ret = video_register_media_controller(vdev);
 
        /* Part 6: Activate this minor. The char device can now be used. */
        set_bit(V4L2_FL_REGISTERED, &vdev->flags);
diff --git a/drivers/media/v4l2-core/v4l2-mem2mem.c 
b/drivers/media/v4l2-core/v4l2-mem2mem.c
index c4f963d96a79..c9ee141c2b33 100644
--- a/drivers/media/v4l2-core/v4l2-mem2mem.c
+++ b/drivers/media/v4l2-core/v4l2-mem2mem.c
@@ -17,9 +17,11 @@
 #include <linux/sched.h>
 #include <linux/slab.h>
 
+#include <media/media-device.h>
 #include <media/videobuf2-v4l2.h>
 #include <media/v4l2-mem2mem.h>
 #include <media/v4l2-dev.h>
+#include <media/v4l2-device.h>
 #include <media/v4l2-fh.h>
 #include <media/v4l2-event.h>
 
@@ -50,6 +52,19 @@ module_param(debug, bool, 0644);
  * offsets but for different queues */
 #define DST_QUEUE_OFF_BASE     (1 << 30)
 
+enum v4l2_m2m_entity_type {
+       MEM2MEM_ENT_TYPE_SOURCE,
+       MEM2MEM_ENT_TYPE_SINK,
+       MEM2MEM_ENT_TYPE_PROC,
+       MEM2MEM_ENT_TYPE_MAX
+};
+
+static const char * const m2m_entity_name[] = {
+       "source",
+       "sink",
+       "proc"
+};
+
 
 /**
  * struct v4l2_m2m_dev - per-device context
@@ -60,6 +75,15 @@ module_param(debug, bool, 0644);
  */
 struct v4l2_m2m_dev {
        struct v4l2_m2m_ctx     *curr_ctx;
+#ifdef CONFIG_MEDIA_CONTROLLER
+       struct media_entity     *source;
+       struct media_pad        source_pad;
+       struct media_entity     sink;
+       struct media_pad        sink_pad;
+       struct media_entity     proc;
+       struct media_pad        proc_pads[2];
+       struct media_intf_devnode *intf_devnode;
+#endif
 
        struct list_head        job_queue;
        spinlock_t              job_spinlock;
@@ -595,6 +619,158 @@ int v4l2_m2m_mmap(struct file *file, struct v4l2_m2m_ctx 
*m2m_ctx,
 }
 EXPORT_SYMBOL(v4l2_m2m_mmap);
 
+void v4l2_m2m_unregister_media_controller(struct v4l2_m2m_dev *m2m_dev)
+{
+       media_remove_intf_links(&m2m_dev->intf_devnode->intf);
+       media_devnode_remove(m2m_dev->intf_devnode);
+
+       media_entity_remove_links(m2m_dev->source);
+       media_entity_remove_links(&m2m_dev->sink);
+       media_entity_remove_links(&m2m_dev->proc);
+       media_device_unregister_entity(m2m_dev->source);
+       media_device_unregister_entity(&m2m_dev->sink);
+       media_device_unregister_entity(&m2m_dev->proc);
+}
+EXPORT_SYMBOL_GPL(v4l2_m2m_unregister_media_controller);
+
+#if defined(CONFIG_MEDIA_CONTROLLER)
+static int v4l2_m2m_register_entity(struct media_device *mdev,
+       struct v4l2_m2m_dev *m2m_dev, enum v4l2_m2m_entity_type type,
+       int function)
+{
+       struct media_entity *entity;
+       struct media_pad *pads;
+       int num_pads;
+       int ret;
+
+       switch (type) {
+       case MEM2MEM_ENT_TYPE_SOURCE:
+               entity = m2m_dev->source;
+               pads = &m2m_dev->source_pad;
+               entity->name = m2m_entity_name[type];
+               pads[0].flags = MEDIA_PAD_FL_SOURCE;
+               num_pads = 1;
+               break;
+       case MEM2MEM_ENT_TYPE_SINK:
+               entity = &m2m_dev->sink;
+               pads = &m2m_dev->sink_pad;
+               pads[0].flags = MEDIA_PAD_FL_SINK;
+               num_pads = 1;
+               break;
+       case MEM2MEM_ENT_TYPE_PROC:
+               entity = &m2m_dev->proc;
+               pads = m2m_dev->proc_pads;
+               pads[0].flags = MEDIA_PAD_FL_SOURCE;
+               pads[1].flags = MEDIA_PAD_FL_SINK;
+               num_pads = 2;
+               break;
+       default:
+               return -EINVAL;
+       }
+
+       entity->obj_type = MEDIA_ENTITY_TYPE_BASE;
+       entity->name = m2m_entity_name[type];
+       entity->function = function;
+
+       ret = media_entity_pads_init(entity, num_pads, pads);
+       if (ret)
+               return ret;
+       ret = media_device_register_entity(mdev, entity);
+       if (ret)
+               return ret;
+
+       return 0;
+}
+#endif
+
+int v4l2_m2m_register_media_controller(struct v4l2_m2m_dev *m2m_dev,
+               struct video_device *vdev, int function)
+{
+#if defined(CONFIG_MEDIA_CONTROLLER)
+       struct media_device *mdev = vdev->v4l2_dev->mdev;
+       struct media_link *link;
+       int ret;
+
+       if (!mdev)
+               return 0;
+
+       /* A memory-to-memory device consists in two
+        * DMA engine and one video processing entities.
+        * The DMA engine entities are linked to a V4L interface
+        */
+
+       /* Create the three entities with their pads */
+       m2m_dev->source = &vdev->entity;
+       ret = v4l2_m2m_register_entity(mdev, m2m_dev,
+                       MEM2MEM_ENT_TYPE_SOURCE, MEDIA_ENT_F_IO_V4L);
+       if (ret)
+               return ret;
+       ret = v4l2_m2m_register_entity(mdev, m2m_dev,
+                       MEM2MEM_ENT_TYPE_PROC, function);
+       if (ret)
+               goto err_rel_entity0;
+       ret = v4l2_m2m_register_entity(mdev, m2m_dev,
+                       MEM2MEM_ENT_TYPE_SINK, MEDIA_ENT_F_IO_V4L);
+       if (ret)
+               goto err_rel_entity1;
+
+       /* Connect the three entities */
+       ret = media_create_pad_link(&m2m_dev->sink, 0, &m2m_dev->proc, 1,
+                       MEDIA_LNK_FL_IMMUTABLE | MEDIA_LNK_FL_ENABLED);
+       if (ret)
+               goto err_rel_entity2;
+
+       ret = media_create_pad_link(&m2m_dev->proc, 0, m2m_dev->source, 0,
+                       MEDIA_LNK_FL_IMMUTABLE | MEDIA_LNK_FL_ENABLED);
+       if (ret)
+               goto err_rm_links0;
+
+       /* Create video interface */
+       m2m_dev->intf_devnode = media_devnode_create(mdev,
+                       MEDIA_INTF_T_V4L_VIDEO, 0,
+                       VIDEO_MAJOR, vdev->minor);
+       if (!m2m_dev->intf_devnode) {
+               ret = -ENOMEM;
+               goto err_rm_links1;
+       }
+
+       /* Connect the two DMA engines to the interface */
+       link = media_create_intf_link(m2m_dev->source,
+                       &m2m_dev->intf_devnode->intf, MEDIA_LNK_FL_ENABLED);
+       if (!link) {
+               ret = -ENOMEM;
+               goto err_rm_devnode;
+       }
+
+       link = media_create_intf_link(&m2m_dev->sink,
+                       &m2m_dev->intf_devnode->intf, MEDIA_LNK_FL_ENABLED);
+       if (!link) {
+               ret = -ENOMEM;
+               goto err_rm_intf_link;
+       }
+       return 0;
+
+err_rm_intf_link:
+       media_remove_intf_links(&m2m_dev->intf_devnode->intf);
+err_rm_devnode:
+       media_devnode_remove(m2m_dev->intf_devnode);
+err_rm_links1:
+       media_entity_remove_links(&m2m_dev->sink);
+err_rm_links0:
+       media_entity_remove_links(&m2m_dev->proc);
+       media_entity_remove_links(m2m_dev->source);
+err_rel_entity2:
+       media_device_unregister_entity(&m2m_dev->proc);
+err_rel_entity1:
+       media_device_unregister_entity(&m2m_dev->sink);
+err_rel_entity0:
+       media_device_unregister_entity(m2m_dev->source);
+       return ret;
+#endif
+       return 0;
+}
+EXPORT_SYMBOL_GPL(v4l2_m2m_register_media_controller);
+
 struct v4l2_m2m_dev *v4l2_m2m_init(const struct v4l2_m2m_ops *m2m_ops)
 {
        struct v4l2_m2m_dev *m2m_dev;
diff --git a/include/media/v4l2-mem2mem.h b/include/media/v4l2-mem2mem.h
index 3d07ba3a8262..36e252d2149a 100644
--- a/include/media/v4l2-mem2mem.h
+++ b/include/media/v4l2-mem2mem.h
@@ -53,6 +53,7 @@ struct v4l2_m2m_ops {
        void (*unlock)(void *priv);
 };
 
+struct video_device;
 struct v4l2_m2m_dev;
 
 /**
@@ -328,6 +329,10 @@ int v4l2_m2m_mmap(struct file *file, struct v4l2_m2m_ctx 
*m2m_ctx,
  */
 struct v4l2_m2m_dev *v4l2_m2m_init(const struct v4l2_m2m_ops *m2m_ops);
 
+void v4l2_m2m_unregister_media_controller(struct v4l2_m2m_dev *m2m_dev);
+int v4l2_m2m_register_media_controller(struct v4l2_m2m_dev *m2m_dev,
+                       struct video_device *vdev, int function);
+
 /**
  * v4l2_m2m_release() - cleans up and frees a m2m_dev structure
  *
diff --git a/include/uapi/linux/media.h b/include/uapi/linux/media.h
index c7e9a5cba24e..5f58c7ac04c0 100644
--- a/include/uapi/linux/media.h
+++ b/include/uapi/linux/media.h
@@ -132,6 +132,9 @@ struct media_device_info {
 #define MEDIA_ENT_F_PROC_VIDEO_LUT             (MEDIA_ENT_F_BASE + 0x4004)
 #define MEDIA_ENT_F_PROC_VIDEO_SCALER          (MEDIA_ENT_F_BASE + 0x4005)
 #define MEDIA_ENT_F_PROC_VIDEO_STATISTICS      (MEDIA_ENT_F_BASE + 0x4006)
+#define MEDIA_ENT_F_PROC_VIDEO_DECODER         (MEDIA_ENT_F_BASE + 0x4007)
+#define MEDIA_ENT_F_PROC_VIDEO_ENCODER         (MEDIA_ENT_F_BASE + 0x4008)
+#define MEDIA_ENT_F_PROC_VIDEO_DEINTERLACER    (MEDIA_ENT_F_BASE + 0x4009)
 
 /*
  * Switch and bridge entity functions
-- 
2.17.1

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