@@ -17,6 +17,7 @@
 #include <linux/hashtable.h>
 #include <linux/list.h>
 #include <linux/module.h>
+#include <linux/notifier.h>
 #include <linux/refcount.h>
 #include <linux/scmi_protocol.h>
 #include <linux/spinlock.h>

@@ -527,5 +528,8 @@ static struct platform_driver __drv = {					       \
 void scmi_notification_instance_data_set(const struct scmi_handle *handle,
 					 void *priv);
 void *scmi_notification_instance_data_get(const struct scmi_handle *handle);
+int scmi_notifier_register(const struct scmi_handle *handle, u8 proto_id,
+			   u8 evt_id, const u32 *src_id,
+			   struct notifier_block *nb);
 int scmi_inflight_count(const struct scmi_handle *handle);
 #endif /* _SCMI_COMMON_H */

@@ -1657,6 +1657,17 @@ static void *scmi_get_protocol_priv(const struct scmi_protocol_handle *ph)
 	return pi->priv;
 }
 
+static int
+scmi_register_instance_notifier(const struct scmi_protocol_handle *ph,
+				u8 evt_id, const u32 *src_id,
+				struct notifier_block *nb)
+{
+	const struct scmi_protocol_instance *pi = ph_to_pi(ph);
+
+	return scmi_notifier_register(pi->handle, pi->proto->id,
+				      evt_id, src_id, nb);
+}
+
 static const struct scmi_xfer_ops xfer_ops = {
 	.version_get = version_get,
 	.xfer_get_init = xfer_get_init,

@@ -2156,6 +2167,7 @@ scmi_alloc_init_protocol_instance(struct scmi_info *info,
 	pi->ph.hops = &helpers_ops;
 	pi->ph.set_priv = scmi_set_protocol_priv;
 	pi->ph.get_priv = scmi_get_protocol_priv;
+	pi->ph.notifier_register = scmi_register_instance_notifier;
 	refcount_set(&pi->users, 1);
 	/* proto->init is assured NON NULL by scmi_protocol_register */
 	ret = pi->proto->instance_init(&pi->ph);

@@ -593,7 +593,13 @@ int scmi_notify(const struct scmi_handle *handle, u8 proto_id, u8 evt_id,
 	if (!r_evt)
 		return -EINVAL;
 
-	if (len > r_evt->evt->max_payld_sz) {
+	/*
+	 * Events with a zero max_payld_sz are sized to be of the maximum
+	 * size allowed by the transport: no need to be size-checked here
+	 * since the transport layer would have already dropped such
+	 * over-sized messages.
+	 */
+	if (r_evt->evt->max_payld_sz && len > r_evt->evt->max_payld_sz) {
 		dev_err(handle->dev, "discard badly sized message\n");
 		return -EINVAL;
 	}

@@ -752,7 +758,7 @@ int scmi_register_protocol_events(const struct scmi_handle *handle, u8 proto_id,
 				  const struct scmi_protocol_handle *ph,
 				  const struct scmi_protocol_events *ee)
 {
-	int i;
+	int i, max_msg_sz;
 	unsigned int num_sources;
 	size_t payld_sz = 0;
 	struct scmi_registered_events_desc *pd;

@@ -767,6 +773,8 @@ int scmi_register_protocol_events(const struct scmi_handle *handle, u8 proto_id,
 	if (!ni)
 		return -ENOMEM;
 
+	max_msg_sz = ph->hops->get_max_msg_size(ph);
+
 	/* num_sources cannot be <= 0 */
 	if (ee->num_sources) {
 		num_sources = ee->num_sources;

@@ -779,8 +787,13 @@ int scmi_register_protocol_events(const struct scmi_handle *handle, u8 proto_id,
 	}
 
 	evt = ee->evts;
-	for (i = 0; i < ee->num_events; i++)
+	for (i = 0; i < ee->num_events; i++) {
+		if (evt[i].max_payld_sz == 0) {
+			payld_sz = max_msg_sz;
+			break;
+		}
 		payld_sz = max_t(size_t, payld_sz, evt[i].max_payld_sz);
+	}
 	payld_sz += sizeof(struct scmi_event_header);
 
 	pd = scmi_allocate_registered_events_desc(ni, proto_id, ee->queue_sz,

@@ -809,7 +822,8 @@ int scmi_register_protocol_events(const struct scmi_handle *handle, u8 proto_id,
 		mutex_init(&r_evt->sources_mtx);
 
 		r_evt->report = devm_kzalloc(ni->handle->dev,
-					     evt->max_report_sz, GFP_KERNEL);
+					     evt->max_report_sz ?: max_msg_sz,
+					     GFP_KERNEL);
 		if (!r_evt->report)
 			return -ENOMEM;
 

@@ -1373,9 +1387,9 @@ static int scmi_event_handler_enable_events(struct scmi_event_handler *hndl)
  *
  * Return: 0 on Success
  */
-static int scmi_notifier_register(const struct scmi_handle *handle,
-				  u8 proto_id, u8 evt_id, const u32 *src_id,
-				  struct notifier_block *nb)
+int scmi_notifier_register(const struct scmi_handle *handle,
+			   u8 proto_id, u8 evt_id, const u32 *src_id,
+			   struct notifier_block *nb)
 {
 	int ret = 0;
 	u32 evt_key;

@@ -18,8 +18,12 @@
 /**
  * struct scmi_event  - Describes an event to be supported
  * @id: Event ID
- * @max_payld_sz: Max possible size for the payload of a notification message
- * @max_report_sz: Max possible size for the report of a notification message
+ * @max_payld_sz: Max possible size for the payload of a notification message.
+ *		  Set to zero to use the maximum payload size allowed by the
+ *		  transport.
+ * @max_report_sz: Max possible size for the report of a notification message.
+ *		  Set to zero to use the maximum payload size allowed by the
+ *		  transport.
  *
  * Each SCMI protocol, during its initialization phase, can describe the events
  * it wishes to support in a few struct scmi_event and pass them to the core

@@ -163,6 +163,9 @@ struct scmi_proto_helpers_ops;
  *	  can be used by the protocol implementation to generate SCMI messages.
  * @set_priv: A method to set protocol private data for this instance.
  * @get_priv: A method to get protocol private data previously set.
+ * @notifier_register: A method to register interest for notifications from
+ *		       within a protocol implementation unit: notifiers can
+ *		       be registered only for the same protocol.
  *
  * This structure represents a protocol initialized against specific SCMI
  * instance and it will be used as follows:

@@ -182,6 +185,9 @@ struct scmi_protocol_handle {
 	int (*set_priv)(const struct scmi_protocol_handle *ph, void *priv,
 			u32 version);
 	void *(*get_priv)(const struct scmi_protocol_handle *ph);
+	int (*notifier_register)(const struct scmi_protocol_handle *ph,
+				 u8 evt_id, const u32 *src_id,
+				 struct notifier_block *nb);
 };
 
 /**