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:

- entity 1: input (1 pad, 1 link)
            type Node subtype Unknown flags 0
        pad0: Source
                -> "proc":1 [ENABLED,IMMUTABLE]

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

- entity 6: output (1 pad, 1 link)
            type Node subtype Unknown flags 0
        pad0: Sink
                <- "proc":0 [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     |  23 ++--
 drivers/media/v4l2-core/v4l2-mem2mem.c | 157 +++++++++++++++++++++++++
 include/media/media-entity.h           |   4 +
 include/media/v4l2-dev.h               |   2 +
 include/media/v4l2-mem2mem.h           |   5 +
 include/uapi/linux/media.h             |   2 +
 6 files changed, 186 insertions(+), 7 deletions(-)

diff --git a/drivers/media/v4l2-core/v4l2-dev.c 
b/drivers/media/v4l2-core/v4l2-dev.c
index 4ffd7d60a901..ec8f20f0fdc5 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_type != VFL_TYPE_MEM2MEM) {
                /* Remove interfaces and interface links */
                media_devnode_remove(vdev->intf_devnode);
                if (vdev->entity.function != MEDIA_ENT_F_UNKNOWN)
@@ -530,6 +530,7 @@ static void determine_valid_ioctls(struct video_device 
*vdev)
        bool is_radio = vdev->vfl_type == VFL_TYPE_RADIO;
        bool is_sdr = vdev->vfl_type == VFL_TYPE_SDR;
        bool is_tch = vdev->vfl_type == VFL_TYPE_TOUCH;
+       bool is_m2m = vdev->vfl_type == VFL_TYPE_MEM2MEM;
        bool is_rx = vdev->vfl_dir != VFL_DIR_TX;
        bool is_tx = vdev->vfl_dir != VFL_DIR_RX;
 
@@ -576,7 +577,7 @@ static void determine_valid_ioctls(struct video_device 
*vdev)
        if (ops->vidioc_enum_freq_bands || ops->vidioc_g_tuner || 
ops->vidioc_g_modulator)
                set_bit(_IOC_NR(VIDIOC_ENUM_FREQ_BANDS), valid_ioctls);
 
-       if (is_vid || is_tch) {
+       if (is_vid || is_m2m || is_tch) {
                /* video and metadata specific ioctls */
                if ((is_rx && (ops->vidioc_enum_fmt_vid_cap ||
                               ops->vidioc_enum_fmt_vid_cap_mplane ||
@@ -669,7 +670,7 @@ static void determine_valid_ioctls(struct video_device 
*vdev)
                        set_bit(_IOC_NR(VIDIOC_TRY_FMT), valid_ioctls);
        }
 
-       if (is_vid || is_vbi || is_sdr || is_tch) {
+       if (is_vid || is_m2m || is_vbi || is_sdr || is_tch) {
                /* ioctls valid for video, metadata, vbi or sdr */
                SET_VALID_IOCTL(ops, VIDIOC_REQBUFS, vidioc_reqbufs);
                SET_VALID_IOCTL(ops, VIDIOC_QUERYBUF, vidioc_querybuf);
@@ -682,7 +683,7 @@ static void determine_valid_ioctls(struct video_device 
*vdev)
                SET_VALID_IOCTL(ops, VIDIOC_STREAMOFF, vidioc_streamoff);
        }
 
-       if (is_vid || is_vbi || is_tch) {
+       if (is_vid || is_m2m || is_vbi || is_tch) {
                /* ioctls valid for video or vbi */
                if (ops->vidioc_s_std)
                        set_bit(_IOC_NR(VIDIOC_ENUMSTD), valid_ioctls);
@@ -733,7 +734,7 @@ 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;
@@ -745,7 +746,7 @@ static int video_register_media_controller(struct 
video_device *vdev, int type)
        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;
@@ -774,6 +775,10 @@ static int video_register_media_controller(struct 
video_device *vdev, int type)
                intf_type = MEDIA_INTF_T_V4L_SUBDEV;
                /* Entity will be created via v4l2_device_register_subdev() */
                break;
+       case VFL_TYPE_MEM2MEM:
+               /* Memory-to-memory devices are more complex and use
+                * their own function to register.
+                */
        default:
                return 0;
        }
@@ -869,6 +874,10 @@ int __video_register_device(struct video_device *vdev,
        case VFL_TYPE_TOUCH:
                name_base = "v4l-touch";
                break;
+       case VFL_TYPE_MEM2MEM:
+               /* Maintain this name for backwards compatibility */
+               name_base = "video";
+               break;
        default:
                pr_err("%s called with unknown type: %d\n",
                       __func__, type);
@@ -993,7 +1002,7 @@ 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..0505b65bfa68 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 +52,11 @@ module_param(debug, bool, 0644);
  * offsets but for different queues */
 #define DST_QUEUE_OFF_BASE     (1 << 30)
 
+struct v4l2_m2m_entity {
+       struct media_entity entity;
+       struct media_pad pads[2];
+       char name[64];
+};
 
 /**
  * struct v4l2_m2m_dev - per-device context
@@ -60,6 +67,10 @@ module_param(debug, bool, 0644);
  */
 struct v4l2_m2m_dev {
        struct v4l2_m2m_ctx     *curr_ctx;
+#ifdef CONFIG_MEDIA_CONTROLLER
+       struct v4l2_m2m_entity  entities[3];
+       struct media_intf_devnode *intf_devnode;
+#endif
 
        struct list_head        job_queue;
        spinlock_t              job_spinlock;
@@ -595,6 +606,152 @@ 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)
+{
+       int i;
+
+       media_remove_intf_links(&m2m_dev->intf_devnode->intf);
+       media_devnode_remove(m2m_dev->intf_devnode);
+
+       for (i = 0; i < 3; i++)
+               media_entity_remove_links(&m2m_dev->entities[i].entity);
+       for (i = 0; i < 3; i++)
+               media_device_unregister_entity(&m2m_dev->entities[i].entity);
+}
+EXPORT_SYMBOL_GPL(v4l2_m2m_unregister_media_controller);
+
+#define MEM2MEM_ENT_TYPE_INPUT 1
+#define MEM2MEM_ENT_TYPE_OUTPUT        2
+#define MEM2MEM_ENT_TYPE_PROC  3
+
+static int v4l2_m2m_register_entity(struct media_device *mdev,
+               struct v4l2_m2m_entity *m2m_entity, int type)
+{
+       unsigned int function;
+       int num_pads;
+       int ret;
+
+       switch (type) {
+       case MEM2MEM_ENT_TYPE_INPUT:
+               function = MEDIA_ENT_F_IO_DMAENGINE;
+               m2m_entity->pads[0].flags = MEDIA_PAD_FL_SOURCE;
+               strlcpy(m2m_entity->name, "input", sizeof(m2m_entity->name));
+               num_pads = 1;
+               break;
+       case MEM2MEM_ENT_TYPE_OUTPUT:
+               function = MEDIA_ENT_F_IO_DMAENGINE;
+               m2m_entity->pads[0].flags = MEDIA_PAD_FL_SINK;
+               strlcpy(m2m_entity->name, "output", sizeof(m2m_entity->name));
+               num_pads = 1;
+               break;
+       case MEM2MEM_ENT_TYPE_PROC:
+               function = MEDIA_ENT_F_PROC_VIDEO_TRANSFORM;
+               m2m_entity->pads[0].flags = MEDIA_PAD_FL_SOURCE;
+               m2m_entity->pads[1].flags = MEDIA_PAD_FL_SINK;
+               strlcpy(m2m_entity->name, "proc", sizeof(m2m_entity->name));
+               num_pads = 2;
+               break;
+       default:
+               return -EINVAL;
+       }
+
+       ret = media_entity_pads_init(&m2m_entity->entity, num_pads, 
m2m_entity->pads);
+       if (ret)
+               return ret;
+
+       m2m_entity->entity.obj_type = MEDIA_ENTITY_TYPE_MEM2MEM;
+       m2m_entity->entity.function = function;
+       m2m_entity->entity.name = m2m_entity->name;
+       ret = media_device_register_entity(mdev, &m2m_entity->entity);
+       if (ret)
+               return ret;
+
+       return 0;
+}
+
+int v4l2_m2m_register_media_controller(struct v4l2_m2m_dev *m2m_dev, struct 
video_device *vdev)
+{
+#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 */
+       ret = v4l2_m2m_register_entity(mdev, &m2m_dev->entities[0], 
MEM2MEM_ENT_TYPE_INPUT);
+       if (ret)
+               return ret;
+       ret = v4l2_m2m_register_entity(mdev, &m2m_dev->entities[1], 
MEM2MEM_ENT_TYPE_PROC);
+       if (ret)
+               goto err_rel_entity0;
+       ret = v4l2_m2m_register_entity(mdev, &m2m_dev->entities[2], 
MEM2MEM_ENT_TYPE_OUTPUT);
+       if (ret)
+               goto err_rel_entity1;
+
+       /* Connect the three entities */
+        ret = media_create_pad_link(&m2m_dev->entities[0].entity, 0,
+                       &m2m_dev->entities[1].entity, 1,
+                        MEDIA_LNK_FL_IMMUTABLE | MEDIA_LNK_FL_ENABLED);
+       if (ret)
+               goto err_rel_entity2;
+
+        ret = media_create_pad_link(&m2m_dev->entities[1].entity, 0,
+                       &m2m_dev->entities[2].entity, 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->entities[0].entity, 
&m2m_dev->intf_devnode->intf,
+                               MEDIA_LNK_FL_ENABLED);
+       if (!link) {
+               ret = -ENOMEM;
+               goto err_rm_devnode;
+       }
+
+       link = media_create_intf_link(&m2m_dev->entities[1].entity, 
&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->entities[2].entity);
+err_rm_links0:
+       media_entity_remove_links(&m2m_dev->entities[1].entity);
+       media_entity_remove_links(&m2m_dev->entities[0].entity);
+err_rel_entity2:
+       media_device_unregister_entity(&m2m_dev->entities[2].entity);
+err_rel_entity1:
+       media_device_unregister_entity(&m2m_dev->entities[1].entity);
+err_rel_entity0:
+       media_device_unregister_entity(&m2m_dev->entities[0].entity);
+       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/media-entity.h b/include/media/media-entity.h
index 3aa3d58d1d58..ff6fbe8333e1 100644
--- a/include/media/media-entity.h
+++ b/include/media/media-entity.h
@@ -206,6 +206,9 @@ struct media_entity_operations {
  *     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_TYPE_V4L2_MEM2MEM:
+ *     The entity is not embedded in any struct, but part of
+ *     a memory-to-memory topology.
  *
  * Media entity objects are often not instantiated directly, but the media
  * entity structure is inherited by (through embedding) other 
subsystem-specific
@@ -222,6 +225,7 @@ enum media_entity_type {
        MEDIA_ENTITY_TYPE_BASE,
        MEDIA_ENTITY_TYPE_VIDEO_DEVICE,
        MEDIA_ENTITY_TYPE_V4L2_SUBDEV,
+       MEDIA_ENTITY_TYPE_MEM2MEM,
 };
 
 /**
diff --git a/include/media/v4l2-dev.h b/include/media/v4l2-dev.h
index 456ac13eca1d..a9df949bb9c3 100644
--- a/include/media/v4l2-dev.h
+++ b/include/media/v4l2-dev.h
@@ -30,6 +30,7 @@
  * @VFL_TYPE_SUBDEV:   for V4L2 subdevices
  * @VFL_TYPE_SDR:      for Software Defined Radio tuners
  * @VFL_TYPE_TOUCH:    for touch sensors
+ * @VFL_TYPE_MEM2MEM:  for mem2mem devices
  * @VFL_TYPE_MAX:      number of VFL types, must always be last in the enum
  */
 enum vfl_devnode_type {
@@ -39,6 +40,7 @@ enum vfl_devnode_type {
        VFL_TYPE_SUBDEV,
        VFL_TYPE_SDR,
        VFL_TYPE_TOUCH,
+       VFL_TYPE_MEM2MEM,
        VFL_TYPE_MAX /* Shall be the last one */
 };
 
diff --git a/include/media/v4l2-mem2mem.h b/include/media/v4l2-mem2mem.h
index 3d07ba3a8262..9dfe9bd23f89 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);
 
+int v4l2_m2m_register_media_controller(struct v4l2_m2m_dev *m2m_dev, struct 
video_device *vdev);
+
+void v4l2_m2m_unregister_media_controller(struct v4l2_m2m_dev *m2m_dev);
+
 /**
  * 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..becb7db77f6a 100644
--- a/include/uapi/linux/media.h
+++ b/include/uapi/linux/media.h
@@ -81,6 +81,7 @@ struct media_device_info {
 #define MEDIA_ENT_F_IO_DTV                     (MEDIA_ENT_F_BASE + 0x01001)
 #define MEDIA_ENT_F_IO_VBI                     (MEDIA_ENT_F_BASE + 0x01002)
 #define MEDIA_ENT_F_IO_SWRADIO                 (MEDIA_ENT_F_BASE + 0x01003)
+#define MEDIA_ENT_F_IO_DMAENGINE               (MEDIA_ENT_F_BASE + 0x01004)
 
 /*
  * Sensor functions
@@ -132,6 +133,7 @@ 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_TRANSFORM       (MEDIA_ENT_F_BASE + 0x4007)
 
 /*
  * Switch and bridge entity functions
-- 
2.17.1

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