drivers: firmware: scmi: add scmi_read_message for notification handling

Introduce scmi_read_message() to allow protocols to read the associated
event payload when a P2A notification is received. This enables protocol
drivers to process notification-specific data after the SCMI core
dispatches the event.

Signed-off-by: Yongxu Wang <[email protected]>

Author: yongxu-wang15

drivers/firmware/scmi/core.c

@@ -258,6 +258,28 @@ int scmi_send_message(struct scmi_protocol *proto, struct scmi_message *msg,
 	}
 }
 
+int scmi_read_message(struct scmi_protocol *proto, struct scmi_message *msg)
+{
+	if (!proto->rx) {
+		return -ENODEV;
+	}
+
+	if (!proto->rx->ready) {
+		return -EINVAL;
+	}
+
+	/* read message from platform, such as notification event
+	 *
+	 * Unlike scmi_send_message, reading messages with scmi_read_message is not currently
+	 * required in the PRE_KERNEL stage. The interrupt-based logic is used here.
+	 */
+	if (k_is_pre_kernel()) {
+		return -EINVAL;
+	}
+
+	return scmi_transport_read_message(proto->transport, proto->rx, msg);
+}
+
 static int scmi_core_protocol_setup(const struct device *transport)
 {
 	int ret;

include/zephyr/drivers/firmware/scmi/protocol.h

@@ -184,4 +184,16 @@ int scmi_send_message(struct scmi_protocol *proto,
 		      struct scmi_message *msg, struct scmi_message *reply,
 		      bool use_polling);
 
+/**
+ * @brief Read an SCMI message
+ *
+ * Blocking function used to read an SCMI message over a given channel
+ *
+ * @param proto pointer to SCMI protocol
+ * @param msg pointer to SCMI message to read
+ *
+ * @retval 0 if successful
+ * @retval negative errno if failure
+ */
+int scmi_read_message(struct scmi_protocol *proto, struct scmi_message *msg);
 #endif /* _INCLUDE_ZEPHYR_DRIVERS_FIRMWARE_SCMI_PROTOCOL_H_ */