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    SubjectRe: [PATCH 3/6] rpmsg: glink: Add support for rpmsg glink chrdev
    On Mon 18 Dec 14:02 PST 2017, Chris Lew wrote:

    > RPMSG provides a char device interface to userspace. Probe the rpmsg
    > chrdev channel to enable the rpmsg_ctrl device creation on glink
    > transports.
    >
    > Signed-off-by: Chris Lew <clew@codeaurora.org>
    > ---
    > drivers/rpmsg/qcom_glink_native.c | 39 +++++++++++++++++++++++++++++++++++++++
    > 1 file changed, 39 insertions(+)
    >
    > diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c
    > index 179132226dc2..786f2eca01f1 100644
    > --- a/drivers/rpmsg/qcom_glink_native.c
    > +++ b/drivers/rpmsg/qcom_glink_native.c
    > @@ -132,6 +132,13 @@ enum {
    > GLINK_STATE_CLOSING,
    > };
    >
    > +struct qcom_glink_device {
    > + struct rpmsg_device rpdev;
    > + struct qcom_glink *glink;
    > +};
    > +
    > +#define to_glink_device(_x) container_of(_x, struct qcom_glink_device, rpdev)
    > +
    > /**
    > * struct glink_channel - internal representation of a channel
    > * @rpdev: rpdev reference, only used for primary endpoints
    > @@ -1339,6 +1346,10 @@ static struct device_node *qcom_glink_match_channel(struct device_node *node,
    > return NULL;
    > }
    >
    > +static const struct rpmsg_device_ops glink_chrdev_ops = {
    > + .create_ept = qcom_glink_create_ept,
    > +};

    I can't remember and I see no apparent reason why we don't just
    advertise the intents as the last step of create_ept, meaning that the
    difference in ops would go away.

    This would also make sure that we do advertise some intents for channels
    associated with the rpmsg_char - and even if we don't have an attached
    driver we can override the intent sizes on a channel.

    > +
    > static const struct rpmsg_device_ops glink_device_ops = {
    > .create_ept = qcom_glink_create_ept,
    > .announce_create = qcom_glink_announce_create,
    > @@ -1547,6 +1558,30 @@ static void qcom_glink_work(struct work_struct *work)
    > }
    > }
    >
    > +static void qcom_glink_device_release(struct device *dev)
    > +{
    > + struct rpmsg_device *rpdev = to_rpmsg_device(dev);
    > + struct qcom_glink_device *gdev = to_glink_device(rpdev);
    > +
    > + kfree(gdev);
    > +}
    > +
    > +static int qcom_glink_create_chrdev(struct qcom_glink *glink)
    > +{
    > + struct qcom_glink_device *gdev;
    > +
    > + gdev = kzalloc(sizeof(*gdev), GFP_KERNEL);
    > + if (!gdev)
    > + return -ENOMEM;
    > +
    > + gdev->glink = glink;
    > + gdev->rpdev.ops = &glink_chrdev_ops;
    > + gdev->rpdev.dev.parent = glink->dev;
    > + gdev->rpdev.dev.release = qcom_glink_device_release;
    > +
    > + return rpmsg_chrdev_register_device(&gdev->rpdev);

    This rpdev will end up being the first parameter to
    qcom_glink_create_ept() where we do:

    container_of(rpdev->ept, struct glink_channel, ept)

    to get the struct glink_channel that backs the endpoint of the passed
    rpmsg_device. So the registered rpdev must reference a rpmsg_endpoint
    that is contained within a glink_channel.


    So I think you need to create two objects here; a glink_channel with
    the glink pointer referencing the glink instance and a rpmsg_device
    referencing the rpmsg_endpoint of the channel.

    You can get a initialized (and dangling) glink_channel by calling
    qcom_glink_alloc_channel(). Note though that this element won't be freed
    automagically (the rpmsg_device will).
    > +}
    > +

    Regards,
    Bjorn

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