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Subject[PATCH 1/2] rpmsg: core: add possibility to get message payload length
Date
Return the rpmsg buffer payload size for sending message, so rpmsg users
can split a long message in several sub rpmsg buffers.

Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@st.com>
Signed-off-by: Fabien Dessenne <fabien.dessenne@st.com>
---
drivers/rpmsg/rpmsg_core.c | 20 ++++++++++++++++++++
drivers/rpmsg/rpmsg_internal.h | 2 ++
drivers/rpmsg/virtio_rpmsg_bus.c | 11 +++++++++++
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 8122807..75c8c40 100644
--- a/drivers/rpmsg/rpmsg_core.c
+++ b/drivers/rpmsg/rpmsg_core.c
@@ -283,6 +283,26 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst,
}
EXPORT_SYMBOL(rpmsg_trysend_offchannel);

+/**
+ * rpmsg_get_buf_payload_size()
+ * This function returns buffer payload size available for sending messages.
+ *
+ * @ept: the rpmsg endpoint
+ *
+ * Returns buffer payload size on success and an appropriate error value on
+ * failure.
+ */
+int rpmsg_get_buf_payload_size(struct rpmsg_endpoint *ept)
+{
+ if (WARN_ON(!ept))
+ return -EINVAL;
+ if (!ept->ops->get_buf_payload_size)
+ return -ENXIO;
+
+ return ept->ops->get_buf_payload_size(ept);
+}
+EXPORT_SYMBOL(rpmsg_get_buf_payload_size);
+
/*
* 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 0d791c3..6f733a5 100644
--- a/drivers/rpmsg/rpmsg_internal.h
+++ b/drivers/rpmsg/rpmsg_internal.h
@@ -46,6 +46,7 @@ struct rpmsg_device_ops {
* @trysend: see @rpmsg_trysend(), required
* @trysendto: see @rpmsg_trysendto(), optional
* @trysend_offchannel: see @rpmsg_trysend_offchannel(), optional
+ * @get_buf_payload_size: see @rpmsg_get_buf_payload_size(), 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
@@ -65,6 +66,7 @@ struct rpmsg_endpoint_ops {
void *data, int len);
__poll_t (*poll)(struct rpmsg_endpoint *ept, struct file *filp,
poll_table *wait);
+ int (*get_buf_payload_size)(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 5d3685b..82753e7 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 int virtio_get_buf_payload_size(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_buf_payload_size = virtio_get_buf_payload_size,
};

/**
@@ -699,6 +701,15 @@ static int virtio_rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src,
return rpmsg_send_offchannel_raw(rpdev, src, dst, data, len, false);
}

+static int virtio_get_buf_payload_size(struct rpmsg_endpoint *ept)
+{
+ struct rpmsg_device *rpdev = ept->rpdev;
+ struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(rpdev);
+ int size = vch->vrp->buf_size - sizeof(struct rpmsg_hdr);
+
+ return size < 0 ? -EMSGSIZE : size;
+}
+
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 9fe156d..250df21 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);

+int rpmsg_get_buf_payload_size(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 int rpmsg_get_buf_payload_size(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 */
--
2.7.4
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