Query to find out temp tablespace usage

SELECT
   A.tablespace_name tablespace,
   D.mb_total,
   SUM (A.used_blocks * D.block_size) / 1024 / 1024 mb_used,
   D.mb_total - SUM (A.used_blocks * D.block_size) / 1024 / 1024 mb_free
FROM
   v$sort_segment A,
(
SELECT
   B.name,
   C.block_size,
   SUM (C.bytes) / 1024 / 1024 mb_total
FROM
   v$tablespace B,
   v$tempfile C
WHERE
   B.ts#= C.ts#
GROUP BY
   B.name,
   C.block_size
) D
WHERE
   A.tablespace_name = D.name
GROUP by
   A.tablespace_name,
   D.mb_total