Return the rpmsg buffer MTU for sending message, so rpmsg users can split a long message in several sub rpmsg buffers. Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@xxxxxx> --- V2[1] to V3 - fix parameter description in rpmsg_device_ops struct [1]: https://lore.kernel.org/patchwork/patch/1124684/ --- drivers/rpmsg/rpmsg_core.c | 21 +++++++++++++++++++++ drivers/rpmsg/rpmsg_internal.h | 2 ++ drivers/rpmsg/virtio_rpmsg_bus.c | 10 ++++++++++ include/linux/rpmsg.h | 10 ++++++++++ 4 files changed, 43 insertions(+) diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c index e330ec4dfc33..a6ef54c4779a 100644 --- a/drivers/rpmsg/rpmsg_core.c +++ b/drivers/rpmsg/rpmsg_core.c @@ -283,6 +283,27 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst, } EXPORT_SYMBOL(rpmsg_trysend_offchannel); +/** + * rpmsg_get_mtu() - get maximum transmission buffer size for sending message. + * @ept: the rpmsg endpoint + * + * This function returns maximum buffer size available for a single message. + * + * Return: the maximum transmission size on success and an appropriate error + * value on failure. + */ + +ssize_t rpmsg_get_mtu(struct rpmsg_endpoint *ept) +{ + if (WARN_ON(!ept)) + return -EINVAL; + if (!ept->ops->get_mtu) + return -ENOTSUPP; + + return ept->ops->get_mtu(ept); +} +EXPORT_SYMBOL(rpmsg_get_mtu); + /* * match an rpmsg channel with a channel info struct. * this is used to make sure we're not creating rpmsg devices for channels diff --git a/drivers/rpmsg/rpmsg_internal.h b/drivers/rpmsg/rpmsg_internal.h index 3fc83cd50e98..e6f88ee90ff6 100644 --- a/drivers/rpmsg/rpmsg_internal.h +++ b/drivers/rpmsg/rpmsg_internal.h @@ -47,6 +47,7 @@ struct rpmsg_device_ops { * @trysendto: see @rpmsg_trysendto(), optional * @trysend_offchannel: see @rpmsg_trysend_offchannel(), optional * @poll: see @rpmsg_poll(), optional + * @get_mtu: see @rpmsg_get_mtu(), optional * * Indirection table for the operations that a rpmsg backend should implement. * In addition to @destroy_ept, the backend must at least implement @send and @@ -66,6 +67,7 @@ struct rpmsg_endpoint_ops { void *data, int len); __poll_t (*poll)(struct rpmsg_endpoint *ept, struct file *filp, poll_table *wait); + ssize_t (*get_mtu)(struct rpmsg_endpoint *ept); }; int rpmsg_register_device(struct rpmsg_device *rpdev); diff --git a/drivers/rpmsg/virtio_rpmsg_bus.c b/drivers/rpmsg/virtio_rpmsg_bus.c index 376ebbf880d6..6e48fdf24555 100644 --- a/drivers/rpmsg/virtio_rpmsg_bus.c +++ b/drivers/rpmsg/virtio_rpmsg_bus.c @@ -175,6 +175,7 @@ static int virtio_rpmsg_trysendto(struct rpmsg_endpoint *ept, void *data, int len, u32 dst); static int virtio_rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst, void *data, int len); +static ssize_t virtio_rpmsg_get_mtu(struct rpmsg_endpoint *ept); static const struct rpmsg_endpoint_ops virtio_endpoint_ops = { .destroy_ept = virtio_rpmsg_destroy_ept, @@ -184,6 +185,7 @@ static const struct rpmsg_endpoint_ops virtio_endpoint_ops = { .trysend = virtio_rpmsg_trysend, .trysendto = virtio_rpmsg_trysendto, .trysend_offchannel = virtio_rpmsg_trysend_offchannel, + .get_mtu = virtio_rpmsg_get_mtu, }; /** @@ -699,6 +701,14 @@ static int virtio_rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, return rpmsg_send_offchannel_raw(rpdev, src, dst, data, len, false); } +static ssize_t virtio_rpmsg_get_mtu(struct rpmsg_endpoint *ept) +{ + struct rpmsg_device *rpdev = ept->rpdev; + struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(rpdev); + + return vch->vrp->buf_size - sizeof(struct rpmsg_hdr); +} + static int rpmsg_recv_single(struct virtproc_info *vrp, struct device *dev, struct rpmsg_hdr *msg, unsigned int len) { diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h index 9fe156d1c018..88d7892ca93d 100644 --- a/include/linux/rpmsg.h +++ b/include/linux/rpmsg.h @@ -135,6 +135,8 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst, __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, struct file *filp, poll_table *wait); +ssize_t rpmsg_get_mtu(struct rpmsg_endpoint *ept); + #else static inline int register_rpmsg_device(struct rpmsg_device *dev) @@ -242,6 +244,14 @@ static inline __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, return 0; } +static inline ssize_t rpmsg_get_mtu(struct rpmsg_endpoint *ept) +{ + /* This shouldn't be possible */ + WARN_ON(1); + + return -ENXIO; +} + #endif /* IS_ENABLED(CONFIG_RPMSG) */ /* use a macro to avoid include chaining to get THIS_MODULE */ -- 2.17.1
