ide: ide_id_has_flush_cache() -> ata_id_flush_enabled()

* Add ata_id_flush_enabled() inline helper to <linux/ata.h>.

* ide_id_has_flush_cache() -> ata_id_flush_enabled()

  The latter one also checks if the command is marked as
  supported in word 83 and validity of words 83 & 86.

Cc: Jeff Garzik <jgarzik@pobox.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/include/linux/ata.h b/include/linux/ata.h
index 8162257..921cf0f 100644
--- a/include/linux/ata.h
+++ b/include/linux/ata.h
@@ -558,6 +558,15 @@
 	return id[ATA_ID_COMMAND_SET_2] & (1 << 12);
 }
 
+static inline int ata_id_flush_enabled(const u16 *id)
+{
+	if (ata_id_has_flush(id) == 0)
+		return 0;
+	if ((id[ATA_ID_CSF_DEFAULT] & 0xC000) != 0x4000)
+		return 0;
+	return id[ATA_ID_CFS_ENABLE_2] & (1 << 12);
+}
+
 static inline int ata_id_has_flush_ext(const u16 *id)
 {
 	if ((id[ATA_ID_COMMAND_SET_2] & 0xC000) != 0x4000)