[PATCH RFC 02/10] mailbox: mpxy: add direct synchronous send

[Amirreza Zarrabi]

Implement send_data_sync() for RPMI MPXY channels, reusing the
existing RPMI message dispatch and returning its status directly
instead of going through mbox_chan_txdone().

Factor per-hart shared-memory acquisition into mpxy_shmem_get()/
mpxy_shmem_put() so both the queued and the new synchronous path pin
the CPU around the same per-hart buffer, keeping a request and its
response on one hart. Calls on separate harts remain independent,
subject to firmware support.

Add rpmi_mbox_send_message_sync() as the RPMI counterpart to
rpmi_mbox_send_message(), for use by the upcoming TEE transport.

Signed-off-by: Amirreza Zarrabi <amirreza.zarrabi@xxxxxxxxxxxxxxxx>
---
 drivers/mailbox/riscv-sbi-mpxy-mbox.c      | 196 ++++++++++++++++++-----------
 include/linux/mailbox/riscv-rpmi-message.h |  13 ++
 2 files changed, 139 insertions(+), 70 deletions(-)

diff --git a/drivers/mailbox/riscv-sbi-mpxy-mbox.c b/drivers/mailbox/riscv-sbi-mpxy-mbox.c
index ea69c6b6b4f9..5ca1b6d87f5c 100644
--- a/drivers/mailbox/riscv-sbi-mpxy-mbox.c
+++ b/drivers/mailbox/riscv-sbi-mpxy-mbox.c
@@ -125,54 +125,83 @@ static DEFINE_PER_CPU(struct mpxy_local, mpxy_local);
 static unsigned long mpxy_shmem_size;
 static bool mpxy_shmem_init_done;
 
+static int mpxy_shmem_get(struct mpxy_local **out)
+{
+	struct mpxy_local *mpxy;
+
+	get_cpu();
+	mpxy = this_cpu_ptr(&mpxy_local);
+	if (!mpxy->shmem_active) {
+		put_cpu();
+		return -ENODEV;
+	}
+
+	*out = mpxy;
+	return 0;
+}
+
+static void mpxy_shmem_put(void)
+{
+	put_cpu();
+}
+
 static int mpxy_get_channel_count(u32 *channel_count)
 {
-	struct mpxy_local *mpxy = this_cpu_ptr(&mpxy_local);
-	struct sbi_mpxy_channel_ids_data *sdata = mpxy->shmem;
+	struct mpxy_local *mpxy;
+	struct sbi_mpxy_channel_ids_data *sdata;
 	u32 remaining, returned;
 	struct sbiret sret;
+	int rc;
 
-	if (!mpxy->shmem_active)
-		return -ENODEV;
 	if (!channel_count)
 		return -EINVAL;
 
-	get_cpu();
+	rc = mpxy_shmem_get(&mpxy);
+	if (rc)
+		return rc;
+	sdata = mpxy->shmem;
 
 	/* Get the remaining and returned fields to calculate total */
 	sret = sbi_ecall(SBI_EXT_MPXY, SBI_EXT_MPXY_GET_CHANNEL_IDS,
 			 0, 0, 0, 0, 0, 0);
-	if (sret.error)
-		goto err_put_cpu;
+	if (sret.error) {
+		rc = sbi_err_map_linux_errno(sret.error);
+		goto out;
+	}
 
 	remaining = le32_to_cpu(sdata->remaining);
 	returned = le32_to_cpu(sdata->returned);
 	*channel_count = remaining + returned;
+	rc = 0;
 
-err_put_cpu:
-	put_cpu();
-	return sbi_err_map_linux_errno(sret.error);
+out:
+	mpxy_shmem_put();
+	return rc;
 }
 
 static int mpxy_get_channel_ids(u32 channel_count, u32 *channel_ids)
 {
-	struct mpxy_local *mpxy = this_cpu_ptr(&mpxy_local);
-	struct sbi_mpxy_channel_ids_data *sdata = mpxy->shmem;
+	struct mpxy_local *mpxy;
+	struct sbi_mpxy_channel_ids_data *sdata;
 	u32 remaining, returned, count, start_index = 0;
 	struct sbiret sret;
+	int rc;
 
-	if (!mpxy->shmem_active)
-		return -ENODEV;
 	if (!channel_count || !channel_ids)
 		return -EINVAL;
 
-	get_cpu();
+	rc = mpxy_shmem_get(&mpxy);
+	if (rc)
+		return rc;
+	sdata = mpxy->shmem;
 
 	do {
 		sret = sbi_ecall(SBI_EXT_MPXY, SBI_EXT_MPXY_GET_CHANNEL_IDS,
 				 start_index, 0, 0, 0, 0, 0);
-		if (sret.error)
-			goto err_put_cpu;
+		if (sret.error) {
+			rc = sbi_err_map_linux_errno(sret.error);
+			goto out;
+		}
 
 		remaining = le32_to_cpu(sdata->remaining);
 		returned = le32_to_cpu(sdata->returned);
@@ -182,55 +211,61 @@ static int mpxy_get_channel_ids(u32 channel_count, u32 *channel_ids)
 		memcpy_from_le32(&channel_ids[start_index], sdata->channel_array, count);
 		start_index += count;
 	} while (remaining && start_index < channel_count);
+	rc = 0;
 
-err_put_cpu:
-	put_cpu();
-	return sbi_err_map_linux_errno(sret.error);
+out:
+	mpxy_shmem_put();
+	return rc;
 }
 
 static int mpxy_read_attrs(u32 channel_id, u32 base_attrid, u32 attr_count,
 			   u32 *attrs_buf)
 {
-	struct mpxy_local *mpxy = this_cpu_ptr(&mpxy_local);
+	struct mpxy_local *mpxy;
 	struct sbiret sret;
+	int rc;
 
-	if (!mpxy->shmem_active)
-		return -ENODEV;
 	if (!attr_count || !attrs_buf)
 		return -EINVAL;
 
-	get_cpu();
+	rc = mpxy_shmem_get(&mpxy);
+	if (rc)
+		return rc;
 
 	sret = sbi_ecall(SBI_EXT_MPXY, SBI_EXT_MPXY_READ_ATTRS,
 			 channel_id, base_attrid, attr_count, 0, 0, 0);
-	if (sret.error)
-		goto err_put_cpu;
+	if (sret.error) {
+		rc = sbi_err_map_linux_errno(sret.error);
+		goto out;
+	}
 
 	memcpy_from_le32(attrs_buf, (__le32 *)mpxy->shmem, attr_count);
+	rc = 0;
 
-err_put_cpu:
-	put_cpu();
-	return sbi_err_map_linux_errno(sret.error);
+out:
+	mpxy_shmem_put();
+	return rc;
 }
 
 static int mpxy_write_attrs(u32 channel_id, u32 base_attrid, u32 attr_count,
 			    u32 *attrs_buf)
 {
-	struct mpxy_local *mpxy = this_cpu_ptr(&mpxy_local);
+	struct mpxy_local *mpxy;
 	struct sbiret sret;
+	int rc;
 
-	if (!mpxy->shmem_active)
-		return -ENODEV;
 	if (!attr_count || !attrs_buf)
 		return -EINVAL;
 
-	get_cpu();
+	rc = mpxy_shmem_get(&mpxy);
+	if (rc)
+		return rc;
 
 	memcpy_to_le32((__le32 *)mpxy->shmem, attrs_buf, attr_count);
 	sret = sbi_ecall(SBI_EXT_MPXY, SBI_EXT_MPXY_WRITE_ATTRS,
 			 channel_id, base_attrid, attr_count, 0, 0, 0);
 
-	put_cpu();
+	mpxy_shmem_put();
 	return sbi_err_map_linux_errno(sret.error);
 }
 
@@ -239,16 +274,17 @@ static int mpxy_send_message_with_resp(u32 channel_id, u32 msg_id,
 				       void *rx, unsigned long max_rx_len,
 				       unsigned long *rx_len)
 {
-	struct mpxy_local *mpxy = this_cpu_ptr(&mpxy_local);
+	struct mpxy_local *mpxy;
 	unsigned long rx_bytes;
 	struct sbiret sret;
+	int rc;
 
-	if (!mpxy->shmem_active)
-		return -ENODEV;
 	if (!tx && tx_len)
 		return -EINVAL;
 
-	get_cpu();
+	rc = mpxy_shmem_get(&mpxy);
+	if (rc)
+		return rc;
 
 	/* Message protocols allowed to have no data in messages */
 	if (tx_len)
@@ -259,8 +295,8 @@ static int mpxy_send_message_with_resp(u32 channel_id, u32 msg_id,
 	if (rx && !sret.error) {
 		rx_bytes = sret.value;
 		if (rx_bytes > max_rx_len) {
-			put_cpu();
-			return -ENOSPC;
+			rc = -ENOSPC;
+			goto out;
 		}
 
 		memcpy(rx, mpxy->shmem, rx_bytes);
@@ -268,22 +304,25 @@ static int mpxy_send_message_with_resp(u32 channel_id, u32 msg_id,
 			*rx_len = rx_bytes;
 	}
 
-	put_cpu();
-	return sbi_err_map_linux_errno(sret.error);
+	rc = sbi_err_map_linux_errno(sret.error);
+out:
+	mpxy_shmem_put();
+	return rc;
 }
 
 static int mpxy_send_message_without_resp(u32 channel_id, u32 msg_id,
 					  void *tx, unsigned long tx_len)
 {
-	struct mpxy_local *mpxy = this_cpu_ptr(&mpxy_local);
+	struct mpxy_local *mpxy;
 	struct sbiret sret;
+	int rc;
 
-	if (!mpxy->shmem_active)
-		return -ENODEV;
 	if (!tx && tx_len)
 		return -EINVAL;
 
-	get_cpu();
+	rc = mpxy_shmem_get(&mpxy);
+	if (rc)
+		return rc;
 
 	/* Message protocols allowed to have no data in messages */
 	if (tx_len)
@@ -292,40 +331,45 @@ static int mpxy_send_message_without_resp(u32 channel_id, u32 msg_id,
 	sret = sbi_ecall(SBI_EXT_MPXY, SBI_EXT_MPXY_SEND_MSG_WITHOUT_RESP,
 			 channel_id, msg_id, tx_len, 0, 0, 0);
 
-	put_cpu();
-	return sbi_err_map_linux_errno(sret.error);
+	rc = sbi_err_map_linux_errno(sret.error);
+	mpxy_shmem_put();
+	return rc;
 }
 
 static int mpxy_get_notifications(u32 channel_id,
 				  struct sbi_mpxy_notification_data *notif_data,
 				  unsigned long *events_data_len)
 {
-	struct mpxy_local *mpxy = this_cpu_ptr(&mpxy_local);
+	struct mpxy_local *mpxy;
 	struct sbiret sret;
+	int rc;
 
-	if (!mpxy->shmem_active)
-		return -ENODEV;
 	if (!notif_data || !events_data_len)
 		return -EINVAL;
 
-	get_cpu();
+	rc = mpxy_shmem_get(&mpxy);
+	if (rc)
+		return rc;
 
 	sret = sbi_ecall(SBI_EXT_MPXY, SBI_EXT_MPXY_GET_NOTIFICATION_EVENTS,
 			 channel_id, 0, 0, 0, 0, 0);
-	if (sret.error)
-		goto err_put_cpu;
+	if (sret.error) {
+		rc = sbi_err_map_linux_errno(sret.error);
+		goto out;
+	}
 	if (sret.value < 0 || mpxy_shmem_size < sizeof(*notif_data) ||
 	    sret.value > mpxy_shmem_size - sizeof(*notif_data)) {
-		put_cpu();
-		return -EOVERFLOW;
+		rc = -EOVERFLOW;
+		goto out;
 	}
 
 	memcpy(notif_data, mpxy->shmem, sret.value + sizeof(*notif_data));
 	*events_data_len = sret.value;
 
-err_put_cpu:
-	put_cpu();
-	return sbi_err_map_linux_errno(sret.error);
+	rc = sbi_err_map_linux_errno(sret.error);
+out:
+	mpxy_shmem_put();
+	return rc;
 }
 
 static int mpxy_get_shmem_size(unsigned long *shmem_size)
@@ -402,8 +446,8 @@ 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;
 	switch (msg->type) {
@@ -474,6 +518,8 @@ static void mpxy_mbox_send_rpmi_data(struct mpxy_mbox_channel *mchan,
 		msg->error = -EOPNOTSUPP;
 		break;
 	}
+
+	return msg->error;
 }
 
 static void mpxy_mbox_peek_rpmi_data(struct mbox_chan *chan,
@@ -516,12 +562,21 @@ static int mpxy_mbox_send_data(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;
-	}
+	if (mchan->attrs.msg_proto_id != SBI_MPXY_MSGPROTO_RPMI_ID)
+		return -EOPNOTSUPP;
+
+	mpxy_mbox_send_rpmi_data(mchan, data);
+	return 0;
+}
+
+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)
+		return -EOPNOTSUPP;
 
-	return -EOPNOTSUPP;
+	return mpxy_mbox_send_rpmi_data(mchan, data);
 }
 
 static bool mpxy_mbox_peek_data(struct mbox_chan *chan)
@@ -713,10 +768,11 @@ static void mpxy_mbox_shutdown(struct mbox_chan *chan)
 }
 
 static const struct mbox_chan_ops mpxy_mbox_ops = {
-	.send_data = mpxy_mbox_send_data,
-	.peek_data = mpxy_mbox_peek_data,
-	.startup = mpxy_mbox_startup,
-	.shutdown = mpxy_mbox_shutdown,
+	.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,
 };
 
 /* ====== MPXY platform driver ===== */
diff --git a/include/linux/mailbox/riscv-rpmi-message.h b/include/linux/mailbox/riscv-rpmi-message.h
index d5362b5821f9..16fa85f65d80 100644
--- a/include/linux/mailbox/riscv-rpmi-message.h
+++ b/include/linux/mailbox/riscv-rpmi-message.h
@@ -251,4 +251,17 @@ static inline int rpmi_mbox_send_message(struct mbox_chan *chan,
 	return ret;
 }
 
+static inline int rpmi_mbox_send_message_sync(struct mbox_chan *chan,
+					      struct rpmi_mbox_message *msg)
+{
+	int ret;
+
+	/* Send message for the underlying mailbox channel synchronously */
+	ret = mbox_send_message_sync(chan, msg);
+	if (ret)
+		return ret;
+
+	return msg->error;
+}
+
 #endif /* _LINUX_RISCV_RPMI_MESSAGE_H_ */

-- 
2.34.1