firmware: arm_scmi: Fix SENSOR_AXIS_NAME_GET behaviour when unsupported

Avoid to invoke SENSOR_AXIS_NAME_GET on sensors that have not declared at
least one of their axes as supporting extended names.

Since the returned list of axes supporting extended names is not
necessarily comprising all the existing axes of the specified sensor,
take care also to properly pick the axis descriptor from the ID embedded
in the response.

Link: https://lore.kernel.org/r/20220608164051.2326087-1-cristian.marussi@arm.com
Fixes: 802b0bed ("firmware: arm_scmi: Add SCMI v3.1 SENSOR_AXIS_NAME_GET support")
Cc: Peter Hilber <peter.hilber@opensynergy.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Reviewed-by: Peter Hilber <peter.hilber@opensynergy.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

drivers/firmware/arm_scmi/sensors.c

@@ -358,15 +358,20 @@ static int scmi_sensor_update_intervals(const struct scmi_protocol_handle *ph,
 	return ph->hops->iter_response_run(iter);
 }
 
+struct scmi_apriv {
+	bool any_axes_support_extended_names;
+	struct scmi_sensor_info *s;
+};
+
 static void iter_axes_desc_prepare_message(void *message,
 					   const unsigned int desc_index,
 					   const void *priv)
 {
 	struct scmi_msg_sensor_axis_description_get *msg = message;
-	const struct scmi_sensor_info *s = priv;
+	const struct scmi_apriv *apriv = priv;
 
 	/* Set the number of sensors to be skipped/already read */
-	msg->id = cpu_to_le32(s->id);
+	msg->id = cpu_to_le32(apriv->s->id);
 	msg->axis_desc_index = cpu_to_le32(desc_index);
 }
 
@@ -393,12 +398,14 @@ iter_axes_desc_process_response(const struct scmi_protocol_handle *ph,
 	u32 attrh, attrl;
 	struct scmi_sensor_axis_info *a;
 	size_t dsize = SCMI_MSG_RESP_AXIS_DESCR_BASE_SZ;
-	struct scmi_sensor_info *s = priv;
+	struct scmi_apriv *apriv = priv;
 	const struct scmi_axis_descriptor *adesc = st->priv;
 
 	attrl = le32_to_cpu(adesc->attributes_low);
+	if (SUPPORTS_EXTENDED_AXIS_NAMES(attrl))
+		apriv->any_axes_support_extended_names = true;
 
-	a = &s->axis[st->desc_index + st->loop_idx];
+	a = &apriv->s->axis[st->desc_index + st->loop_idx];
 	a->id = le32_to_cpu(adesc->id);
 	a->extended_attrs = SUPPORTS_EXTEND_ATTRS(attrl);
 
@@ -444,10 +451,19 @@ iter_axes_extended_name_process_response(const struct scmi_protocol_handle *ph,
 					 void *priv)
 {
 	struct scmi_sensor_axis_info *a;
-	const struct scmi_sensor_info *s = priv;
+	const struct scmi_apriv *apriv = priv;
 	struct scmi_sensor_axis_name_descriptor *adesc = st->priv;
+	u32 axis_id = le32_to_cpu(adesc->axis_id);
+
+	if (axis_id >= st->max_resources)
+		return -EPROTO;
 
-	a = &s->axis[st->desc_index + st->loop_idx];
+	/*
+	 * Pick the corresponding descriptor based on the axis_id embedded
+	 * in the reply since the list of axes supporting extended names
+	 * can be a subset of all the axes.
+	 */
+	a = &apriv->s->axis[axis_id];
 	strscpy(a->name, adesc->name, SCMI_MAX_STR_SIZE);
 	st->priv = ++adesc;
 
@@ -458,21 +474,36 @@ static int
 scmi_sensor_axis_extended_names_get(const struct scmi_protocol_handle *ph,
 				    struct scmi_sensor_info *s)
 {
+	int ret;
 	void *iter;
 	struct scmi_iterator_ops ops = {
 		.prepare_message = iter_axes_desc_prepare_message,
 		.update_state = iter_axes_extended_name_update_state,
 		.process_response = iter_axes_extended_name_process_response,
 	};
+	struct scmi_apriv apriv = {
+		.any_axes_support_extended_names = false,
+		.s = s,
+	};
 
 	iter = ph->hops->iter_response_init(ph, &ops, s->num_axis,
 					    SENSOR_AXIS_NAME_GET,
 					    sizeof(struct scmi_msg_sensor_axis_description_get),
-					    s);
+					    &apriv);
 	if (IS_ERR(iter))
 		return PTR_ERR(iter);
 
-	return ph->hops->iter_response_run(iter);
+	/*
+	 * Do not cause whole protocol initialization failure when failing to
+	 * get extended names for axes.
+	 */
+	ret = ph->hops->iter_response_run(iter);
+	if (ret)
+		dev_warn(ph->dev,
+			 "Failed to get axes extended names for %s (ret:%d).\n",
+			 s->name, ret);
+
+	return 0;
 }
 
 static int scmi_sensor_axis_description(const struct scmi_protocol_handle *ph,
@@ -486,6 +517,10 @@ static int scmi_sensor_axis_description(const struct scmi_protocol_handle *ph,
 		.update_state = iter_axes_desc_update_state,
 		.process_response = iter_axes_desc_process_response,
 	};
+	struct scmi_apriv apriv = {
+		.any_axes_support_extended_names = false,
+		.s = s,
+	};
 
 	s->axis = devm_kcalloc(ph->dev, s->num_axis,
 			       sizeof(*s->axis), GFP_KERNEL);
@@ -495,7 +530,7 @@ static int scmi_sensor_axis_description(const struct scmi_protocol_handle *ph,
 	iter = ph->hops->iter_response_init(ph, &ops, s->num_axis,
 					    SENSOR_AXIS_DESCRIPTION_GET,
 					    sizeof(struct scmi_msg_sensor_axis_description_get),
-					    s);
+					    &apriv);
 	if (IS_ERR(iter))
 		return PTR_ERR(iter);
 
@@ -503,7 +538,8 @@ static int scmi_sensor_axis_description(const struct scmi_protocol_handle *ph,
 	if (ret)
 		return ret;
 
-	if (PROTOCOL_REV_MAJOR(version) >= 0x3)
+	if (PROTOCOL_REV_MAJOR(version) >= 0x3 &&
+	    apriv.any_axes_support_extended_names)
 		ret = scmi_sensor_axis_extended_names_get(ph, s);
 
 	return ret;