firmware: arm_scmi: Add asynchronous sensor read if it supports

SENSOR_DESCRIPTION_GET provides attributes to indicate if the sensor
supports asynchronous read. We can read that flag and use asynchronous
reads for any sensors with that attribute set.

Let's use the new scmi_do_xfer_with_response to support asynchronous
sensor reads.
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

drivers/firmware/arm_scmi/sensors.c

@@ -136,9 +136,10 @@ static int scmi_sensor_description_get(const struct scmi_handle *handle,
 		}
 
 		for (cnt = 0; cnt < num_returned; cnt++) {
-			u32 attrh;
+			u32 attrh, attrl;
 			struct scmi_sensor_info *s;
 
+			attrl = le32_to_cpu(buf->desc[cnt].attributes_low);
 			attrh = le32_to_cpu(buf->desc[cnt].attributes_high);
 			s = &si->sensors[desc_index + cnt];
 			s->id = le32_to_cpu(buf->desc[cnt].id);
@@ -147,6 +148,8 @@ static int scmi_sensor_description_get(const struct scmi_handle *handle,
 			/* Sign extend to a full s8 */
 			if (s->scale & SENSOR_SCALE_SIGN)
 				s->scale |= SENSOR_SCALE_EXTEND;
+			s->async = SUPPORTS_ASYNC_READ(attrl);
+			s->num_trip_points = NUM_TRIP_POINTS(attrl);
 			strlcpy(s->name, buf->desc[cnt].name, SCMI_MAX_STR_SIZE);
 		}
 
@@ -214,8 +217,11 @@ static int scmi_sensor_reading_get(const struct scmi_handle *handle,
 				   u32 sensor_id, u64 *value)
 {
 	int ret;
+	__le32 *pval;
 	struct scmi_xfer *t;
 	struct scmi_msg_sensor_reading_get *sensor;
+	struct sensors_info *si = handle->sensor_priv;
+	struct scmi_sensor_info *s = si->sensors + sensor_id;
 
 	ret = scmi_xfer_get_init(handle, SENSOR_READING_GET,
 				 SCMI_PROTOCOL_SENSOR, sizeof(*sensor),
@@ -223,17 +229,25 @@ static int scmi_sensor_reading_get(const struct scmi_handle *handle,
 	if (ret)
 		return ret;
 
+	pval = t->rx.buf;
 	sensor = t->tx.buf;
 	sensor->id = cpu_to_le32(sensor_id);
-	sensor->flags = cpu_to_le32(0);
 
+	if (s->async) {
+		sensor->flags = cpu_to_le32(SENSOR_READ_ASYNC);
+		ret = scmi_do_xfer_with_response(handle, t);
+		if (!ret) {
+			*value = le32_to_cpu(*(pval + 1));
+			*value |= (u64)le32_to_cpu(*(pval + 2)) << 32;
+		}
+	} else {
+		sensor->flags = cpu_to_le32(0);
 		ret = scmi_do_xfer(handle, t);
 		if (!ret) {
-		__le32 *pval = t->rx.buf;
-
 			*value = le32_to_cpu(*pval);
 			*value |= (u64)le32_to_cpu(*(pval + 1)) << 32;
 		}
+	}
 
 	scmi_xfer_put(handle, t);
 	return ret;

include/linux/scmi_protocol.h

@@ -145,6 +145,8 @@ struct scmi_sensor_info {
 	u32 id;
 	u8 type;
 	s8 scale;
+	u8 num_trip_points;
+	bool async;
 	char name[SCMI_MAX_STR_SIZE];
 };