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Subject[PATCH 5/6] rpmsg: virtio: Register the rpmsg_char device
Date
Instantiate the rpmsg_char device on virtio RPMsg bus creation.
This provides the capability, with the RPMSG_CREATE_EPT_IOCTL ioctl,
to create RPMsg char device endpoints relying on the
rpmsg_chrdev_create_eptdev API.

Notice that the created endpoints are attached to the rpmsg_ctldev
device, but not associated to a channel.
As consequence, the endpoint source and destination addresses have to
been specified and there is no channel creation and no name service
announcement to inform the remote side.

Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
---

update vs [1]
- rework the changelog
- remove useless rpdev_ns pointer initialisation.

[1]: https://patchwork.kernel.org/project/linux-remoteproc/patch/20210219111501.14261-12-arnaud.pouliquen@foss.st.com/

---
drivers/rpmsg/virtio_rpmsg_bus.c | 62 +++++++++++++++++++++++++++++---
1 file changed, 57 insertions(+), 5 deletions(-)

diff --git a/drivers/rpmsg/virtio_rpmsg_bus.c b/drivers/rpmsg/virtio_rpmsg_bus.c
index e87d4cf926eb..8e49a3bacfc7 100644
--- a/drivers/rpmsg/virtio_rpmsg_bus.c
+++ b/drivers/rpmsg/virtio_rpmsg_bus.c
@@ -813,14 +813,57 @@ static void rpmsg_xmit_done(struct virtqueue *svq)
wake_up_interruptible(&vrp->sendq);
}

+/*
+ * Called to expose to user a /dev/rpmsg_ctrlX interface allowing to
+ * create endpoint-to-endpoint communication without associated RPMsg channel.
+ * The endpoints are rattached to the ctrldev RPMsg device.
+ */
+static struct rpmsg_device *rpmsg_virtio_add_ctrl_dev(struct virtio_device *vdev)
+{
+ struct virtproc_info *vrp = vdev->priv;
+ struct virtio_rpmsg_channel *vch;
+ struct rpmsg_device *rpdev_ctrl;
+ int err = 0;
+
+ vch = kzalloc(sizeof(*vch), GFP_KERNEL);
+ if (!vch)
+ return ERR_PTR(-ENOMEM);
+
+ /* Link the channel to the vrp */
+ vch->vrp = vrp;
+
+ /* Assign public information to the rpmsg_device */
+ rpdev_ctrl = &vch->rpdev;
+ rpdev_ctrl->ops = &virtio_rpmsg_ops;
+
+ rpdev_ctrl->dev.parent = &vrp->vdev->dev;
+ rpdev_ctrl->dev.release = virtio_rpmsg_release_device;
+ rpdev_ctrl->little_endian = virtio_is_little_endian(vrp->vdev);
+
+ err = rpmsg_chrdev_register_device(rpdev_ctrl);
+ if (err) {
+ kfree(vch);
+ return ERR_PTR(err);
+ }
+
+ return rpdev_ctrl;
+}
+
+static void rpmsg_virtio_del_ctrl_dev(struct rpmsg_device *rpdev_ctrl)
+{
+ if (!rpdev_ctrl)
+ return;
+ kfree(to_virtio_rpmsg_channel(rpdev_ctrl));
+}
+
static int rpmsg_probe(struct virtio_device *vdev)
{
vq_callback_t *vq_cbs[] = { rpmsg_recv_done, rpmsg_xmit_done };
static const char * const names[] = { "input", "output" };
struct virtqueue *vqs[2];
struct virtproc_info *vrp;
- struct virtio_rpmsg_channel *vch;
- struct rpmsg_device *rpdev_ns;
+ struct virtio_rpmsg_channel *vch = NULL;
+ struct rpmsg_device *rpdev_ns, *rpdev_ctrl;
void *bufs_va;
int err = 0, i;
size_t total_buf_space;
@@ -894,12 +937,18 @@ static int rpmsg_probe(struct virtio_device *vdev)

vdev->priv = vrp;

+ rpdev_ctrl = rpmsg_virtio_add_ctrl_dev(vdev);
+ if (IS_ERR(rpdev_ctrl)) {
+ err = PTR_ERR(rpdev_ctrl);
+ goto free_coherent;
+ }
+
/* if supported by the remote processor, enable the name service */
if (virtio_has_feature(vdev, VIRTIO_RPMSG_F_NS)) {
vch = kzalloc(sizeof(*vch), GFP_KERNEL);
if (!vch) {
err = -ENOMEM;
- goto free_coherent;
+ goto free_ctrldev;
}

/* Link the channel to our vrp */
@@ -915,7 +964,7 @@ static int rpmsg_probe(struct virtio_device *vdev)

err = rpmsg_ns_register_device(rpdev_ns);
if (err)
- goto free_coherent;
+ goto free_vch;
}

/*
@@ -939,8 +988,11 @@ static int rpmsg_probe(struct virtio_device *vdev)

return 0;

-free_coherent:
+free_vch:
kfree(vch);
+free_ctrldev:
+ rpmsg_virtio_del_ctrl_dev(rpdev_ctrl);
+free_coherent:
dma_free_coherent(vdev->dev.parent, total_buf_space,
bufs_va, vrp->bufs_dma);
vqs_del:
--
2.17.1
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