mlxsw: thermal: Add function for reading module temperature and thresholds

Provide new function mlxsw_thermal_module_temp_and_thresholds_get() for
reading temperature and temperature thresholds by a single operation.
The motivation is to reduce the number of transactions with the device
which is important when operating over a slow bus such as I2C.

Currently, the sole caller of the function is only using it to read the
module's temperature. The next patch will also use it to query the
module's temperature thresholds.
Signed-off-by: NMykola Kostenok <c_mykolak@nvidia.com>
Acked-by: NVadim Pasternak <vadimp@nvidia.com>
Signed-off-by: NIdo Schimmel <idosch@nvidia.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlxsw/core_thermal.c

@@ -420,29 +420,49 @@ static int mlxsw_thermal_module_unbind(struct thermal_zone_device *tzdev,
 	return err;
 }
 
+static void
+mlxsw_thermal_module_temp_and_thresholds_get(struct mlxsw_core *core,
+					     u16 sensor_index, int *p_temp,
+					     int *p_crit_temp,
+					     int *p_emerg_temp)
+{
+	char mtmp_pl[MLXSW_REG_MTMP_LEN];
+	int err;
+
+	/* Read module temperature and thresholds. */
+	mlxsw_reg_mtmp_pack(mtmp_pl, sensor_index, false, false);
+	err = mlxsw_reg_query(core, MLXSW_REG(mtmp), mtmp_pl);
+	if (err) {
+		/* Set temperature and thresholds to zero to avoid passing
+		 * uninitialized data back to the caller.
+		 */
+		*p_temp = 0;
+		*p_crit_temp = 0;
+		*p_emerg_temp = 0;
+
+		return;
+	}
+	mlxsw_reg_mtmp_unpack(mtmp_pl, p_temp, NULL, p_crit_temp, p_emerg_temp,
+			      NULL);
+}
+
 static int mlxsw_thermal_module_temp_get(struct thermal_zone_device *tzdev,
 					 int *p_temp)
 {
 	struct mlxsw_thermal_module *tz = tzdev->devdata;
 	struct mlxsw_thermal *thermal = tz->parent;
-	struct device *dev = thermal->bus_info->dev;
-	char mtmp_pl[MLXSW_REG_MTMP_LEN];
+	struct device *dev;
+	u16 sensor_index;
 	int temp;
 	int err;
 
-	/* Read module temperature. */
-	mlxsw_reg_mtmp_pack(mtmp_pl, MLXSW_REG_MTMP_MODULE_INDEX_MIN +
-			    tz->module, false, false);
-	err = mlxsw_reg_query(thermal->core, MLXSW_REG(mtmp), mtmp_pl);
-	if (err) {
-		/* Do not return error - in case of broken module's sensor
-		 * it will cause error message flooding.
-		 */
-		temp = 0;
-		*p_temp = (int) temp;
-		return 0;
-	}
-	mlxsw_reg_mtmp_unpack(mtmp_pl, &temp, NULL, NULL, NULL, NULL);
+	dev = thermal->bus_info->dev;
+	sensor_index = MLXSW_REG_MTMP_MODULE_INDEX_MIN + tz->module;
+
+	/* Read module temperature and thresholds. */
+	mlxsw_thermal_module_temp_and_thresholds_get(thermal->core,
+						     sensor_index, &temp, NULL,
+						     NULL);
 	*p_temp = temp;
 
 	if (!temp)