[PATCH 4/4] mailbox: riscv-sbi-mpxy: Move to send_data_sync() for sending messages
From: Anup Patel
Date: Wed Sep 30 2026 - 12:48:32 EST
Currently, the SBI MPXY mailbox driver retrofits synchronous message
exchanges over existing send_data() callback and client driver explicitly
calls mbox_client_txdone().
As a side effect of this retrofitting, all messages sent via SBI MPXY
mailbox channel are serialized using per-channel spinlock which in-turn
prevents multiple CPUs simultaneously sending messages. On the contrary,
the SBI MPXY specification defines per-CPU MPXY shared memory so multiple
CPUs are allowed to send messages in-parallel.
To address the above, update the SBI MPXY mailbox driver to use the
send_data_sync() callback instead of send_data() callback. This removes
the redundant per-channel spinlock from the message sending path thereby
enabling parallel message sending from multiple CPUs. Also, the "error"
field in struct rpmi_mbox_message is now redundant because it was being
used to save the error dropped by msg_submit() function hence remove it.
Co-developed-by: Amirreza Zarrabi <amirreza.zarrabi@xxxxxxxxxxxxxxxx>
Signed-off-by: Amirreza Zarrabi <amirreza.zarrabi@xxxxxxxxxxxxxxxx>
Signed-off-by: Anup Patel <anup.patel@xxxxxxxxxxxxxxxx>
---
drivers/clk/clk-rpmi.c | 2 +-
drivers/irqchip/irq-riscv-rpmi-sysmsi.c | 2 +-
drivers/mailbox/riscv-sbi-mpxy-mbox.c | 59 +++++++++++-----------
include/linux/mailbox/riscv-rpmi-message.h | 18 +------
4 files changed, 34 insertions(+), 47 deletions(-)
diff --git a/drivers/clk/clk-rpmi.c b/drivers/clk/clk-rpmi.c
index 921296aafa68..e365cb8a8dac 100644
--- a/drivers/clk/clk-rpmi.c
+++ b/drivers/clk/clk-rpmi.c
@@ -527,7 +527,7 @@ static int rpmi_clk_probe(struct platform_device *pdev)
context->client.dev = context->dev;
context->client.rx_callback = NULL;
context->client.tx_block = false;
- context->client.knows_txdone = true;
+ context->client.tx_sync = true;
context->client.tx_tout = 0;
context->chan = mbox_request_channel(&context->client, 0);
diff --git a/drivers/irqchip/irq-riscv-rpmi-sysmsi.c b/drivers/irqchip/irq-riscv-rpmi-sysmsi.c
index 612f3972f7af..ca638900aa74 100644
--- a/drivers/irqchip/irq-riscv-rpmi-sysmsi.c
+++ b/drivers/irqchip/irq-riscv-rpmi-sysmsi.c
@@ -224,7 +224,7 @@ static int rpmi_sysmsi_probe(struct platform_device *pdev)
priv->client.dev = priv->dev;
priv->client.rx_callback = NULL;
priv->client.tx_block = false;
- priv->client.knows_txdone = true;
+ priv->client.tx_sync = true;
priv->client.tx_tout = 0;
/* Request mailbox channel */
diff --git a/drivers/mailbox/riscv-sbi-mpxy-mbox.c b/drivers/mailbox/riscv-sbi-mpxy-mbox.c
index cba95b8406ee..18d5ed0b1561 100644
--- a/drivers/mailbox/riscv-sbi-mpxy-mbox.c
+++ b/drivers/mailbox/riscv-sbi-mpxy-mbox.c
@@ -112,10 +112,10 @@ struct mpxy_mbox {
/* ====== MPXY RPMI processing ====== */
-static void mpxy_mbox_send_rpmi_data(struct mpxy_mbox_channel *mchan,
- struct rpmi_mbox_message *msg)
+static int mpxy_mbox_send_rpmi_data(struct mpxy_mbox_channel *mchan,
+ struct rpmi_mbox_message *msg)
{
- msg->error = 0;
+ int error = 0;
switch (msg->type) {
case RPMI_MBOX_MSG_TYPE_GET_ATTRIBUTE:
switch (msg->attr.id) {
@@ -138,52 +138,54 @@ static void mpxy_mbox_send_rpmi_data(struct mpxy_mbox_channel *mchan,
msg->attr.value = mchan->rpmi_attrs.impl_version;
break;
default:
- msg->error = -EOPNOTSUPP;
+ error = -EOPNOTSUPP;
break;
}
break;
case RPMI_MBOX_MSG_TYPE_SET_ATTRIBUTE:
/* None of the RPMI linux mailbox attributes are writeable */
- msg->error = -EOPNOTSUPP;
+ error = -EOPNOTSUPP;
break;
case RPMI_MBOX_MSG_TYPE_SEND_WITH_RESPONSE:
if ((!msg->data.request && msg->data.request_len) ||
(msg->data.request && msg->data.request_len > mchan->max_xfer_len) ||
(!msg->data.response && msg->data.max_response_len)) {
- msg->error = -EINVAL;
+ error = -EINVAL;
break;
}
if (!(mchan->attrs.capability & SBI_MPXY_CHAN_CAP_SEND_WITH_RESP)) {
- msg->error = -EIO;
+ error = -EIO;
break;
}
- msg->error = sbi_mpxy_send_message_with_resp(mchan->channel_id,
- msg->data.service_id,
- msg->data.request,
- msg->data.request_len,
- msg->data.response,
- msg->data.max_response_len,
- &msg->data.out_response_len);
+ error = sbi_mpxy_send_message_with_resp(mchan->channel_id,
+ msg->data.service_id,
+ msg->data.request,
+ msg->data.request_len,
+ msg->data.response,
+ msg->data.max_response_len,
+ &msg->data.out_response_len);
break;
case RPMI_MBOX_MSG_TYPE_SEND_WITHOUT_RESPONSE:
if ((!msg->data.request && msg->data.request_len) ||
(msg->data.request && msg->data.request_len > mchan->max_xfer_len)) {
- msg->error = -EINVAL;
+ error = -EINVAL;
break;
}
if (!(mchan->attrs.capability & SBI_MPXY_CHAN_CAP_SEND_WITHOUT_RESP)) {
- msg->error = -EIO;
+ error = -EIO;
break;
}
- msg->error = sbi_mpxy_send_message_without_resp(mchan->channel_id,
- msg->data.service_id,
- msg->data.request,
- msg->data.request_len);
+ error = sbi_mpxy_send_message_without_resp(mchan->channel_id,
+ msg->data.service_id,
+ msg->data.request,
+ msg->data.request_len);
break;
default:
- msg->error = -EOPNOTSUPP;
+ error = -EOPNOTSUPP;
break;
}
+
+ return error;
}
static void mpxy_mbox_peek_rpmi_data(struct mbox_chan *chan,
@@ -205,7 +207,6 @@ static void mpxy_mbox_peek_rpmi_data(struct mbox_chan *chan,
break;
msg.notif.event_id = event->event_id;
msg.notif.event_data = event->event_data;
- msg.error = 0;
mbox_chan_received_data(chan, &msg);
pos += sizeof(*event) + msg.notif.event_datalen;
@@ -222,16 +223,16 @@ static int mpxy_mbox_read_rpmi_attrs(struct mpxy_mbox_channel *mchan)
/* ====== MPXY mailbox callbacks ====== */
-static int mpxy_mbox_send_data(struct mbox_chan *chan, void *data)
+static int mpxy_mbox_send_data_sync(struct mbox_chan *chan, void *data)
{
struct mpxy_mbox_channel *mchan = chan->con_priv;
- if (mchan->attrs.msg_proto_id == SBI_MPXY_MSGPROTO_RPMI_ID) {
- mpxy_mbox_send_rpmi_data(mchan, data);
- return 0;
+ switch (mchan->attrs.msg_proto_id) {
+ case SBI_MPXY_MSGPROTO_RPMI_ID:
+ return mpxy_mbox_send_rpmi_data(mchan, data);
+ default:
+ return -EOPNOTSUPP;
}
-
- return -EOPNOTSUPP;
}
static bool mpxy_mbox_peek_data(struct mbox_chan *chan)
@@ -423,7 +424,7 @@ static void mpxy_mbox_shutdown(struct mbox_chan *chan)
}
static const struct mbox_chan_ops mpxy_mbox_ops = {
- .send_data = mpxy_mbox_send_data,
+ .send_data_sync = mpxy_mbox_send_data_sync,
.peek_data = mpxy_mbox_peek_data,
.startup = mpxy_mbox_startup,
.shutdown = mpxy_mbox_shutdown,
diff --git a/include/linux/mailbox/riscv-rpmi-message.h b/include/linux/mailbox/riscv-rpmi-message.h
index e135c6564d0c..0278f1cee51f 100644
--- a/include/linux/mailbox/riscv-rpmi-message.h
+++ b/include/linux/mailbox/riscv-rpmi-message.h
@@ -164,7 +164,6 @@ struct rpmi_mbox_message {
u8 *event_data;
} notif;
};
- int error;
};
/* RPMI Linux mailbox message helper routines */
@@ -174,7 +173,6 @@ static inline void rpmi_mbox_init_get_attribute(struct rpmi_mbox_message *msg,
msg->type = RPMI_MBOX_MSG_TYPE_GET_ATTRIBUTE;
msg->attr.id = id;
msg->attr.value = 0;
- msg->error = 0;
}
static inline void rpmi_mbox_init_set_attribute(struct rpmi_mbox_message *msg,
@@ -184,7 +182,6 @@ static inline void rpmi_mbox_init_set_attribute(struct rpmi_mbox_message *msg,
msg->type = RPMI_MBOX_MSG_TYPE_SET_ATTRIBUTE;
msg->attr.id = id;
msg->attr.value = value;
- msg->error = 0;
}
static inline void rpmi_mbox_init_send_with_response(struct rpmi_mbox_message *msg,
@@ -201,7 +198,6 @@ static inline void rpmi_mbox_init_send_with_response(struct rpmi_mbox_message *m
msg->data.response = response;
msg->data.max_response_len = max_response_len;
msg->data.out_response_len = 0;
- msg->error = 0;
}
static inline void rpmi_mbox_init_send_without_response(struct rpmi_mbox_message *msg,
@@ -216,7 +212,6 @@ static inline void rpmi_mbox_init_send_without_response(struct rpmi_mbox_message
msg->data.response = NULL;
msg->data.max_response_len = 0;
msg->data.out_response_len = 0;
- msg->error = 0;
}
static inline void *rpmi_mbox_get_msg_response(struct rpmi_mbox_message *msg)
@@ -227,17 +222,8 @@ static inline void *rpmi_mbox_get_msg_response(struct rpmi_mbox_message *msg)
static inline int rpmi_mbox_send_message(struct mbox_chan *chan,
struct rpmi_mbox_message *msg)
{
- int ret;
-
- /* Send message for the underlying mailbox channel */
- ret = mbox_send_message(chan, msg);
- if (ret < 0)
- return ret;
-
- /* Explicitly signal txdone for mailbox channel */
- ret = msg->error;
- mbox_client_txdone(chan, ret);
- return ret;
+ /* Send message for the underlying mailbox channel synchronously */
+ return mbox_send_message_sync(chan, msg);
}
#endif /* _LINUX_RISCV_RPMI_MESSAGE_H_ */
--
2.43.0