mlxsw: core: Allow thermal zone binding to an external cooling device

Allow thermal zone binding to an external cooling device from the
cooling devices white list.

It provides support for Mellanox next generation systems on which
cooling device logic is not controlled through the switch registers.
Signed-off-by: Vadim Pasternak <vadimp@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -31,6 +31,11 @@
 #define MLXSW_THERMAL_SPEED_MAX		(MLXSW_THERMAL_MAX_STATE * 2)
 #define MLXSW_THERMAL_SPEED_MIN_LEVEL	2		/* 20% */
 
+/* External cooling devices, allowed for binding to mlxsw thermal zones. */
+static char * const mlxsw_thermal_external_allowed_cdev[] = {
+	"mlxreg_fan",
+};
+
 struct mlxsw_thermal_trip {
 	int	type;
 	int	temp;
@@ -107,6 +112,13 @@ static int mlxsw_get_cooling_device_idx(struct mlxsw_thermal *thermal,
 		if (thermal->cdevs[i] == cdev)
 			return i;
 
+	/* Allow mlxsw thermal zone binding to an external cooling device */
+	for (i = 0; i < ARRAY_SIZE(mlxsw_thermal_external_allowed_cdev); i++) {
+		if (strnstr(cdev->type, mlxsw_thermal_external_allowed_cdev[i],
+			    sizeof(cdev->type)))
+			return 0;
+	}
+
 	return -ENODEV;
 }