libata: check for trusted computing in IDENTIFY DEVICE data

ATA-8 and later mirrors the TRUSTED COMPUTING SUPPORTED bit in word 48 of
the IDENTIFY DEVICE data.  Check this before issuing a READ LOG PAGE
command to avoid issues with buggy devices.  The only downside is that
we can't support Security Send / Receive for a device with an older
revision due to the conflicting use of this field in earlier
specifications.

tj: The reason we need this is because some devices which don't
    support READ LOG PAGE lock up after getting issued that command.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/include/linux/ata.h b/include/linux/ata.h
index e65ae4b..c7a3538 100644
--- a/include/linux/ata.h
+++ b/include/linux/ata.h
@@ -60,7 +60,8 @@ enum {
 	ATA_ID_FW_REV		= 23,
 	ATA_ID_PROD		= 27,
 	ATA_ID_MAX_MULTSECT	= 47,
-	ATA_ID_DWORD_IO		= 48,
+	ATA_ID_DWORD_IO		= 48,	/* before ATA-8 */
+	ATA_ID_TRUSTED		= 48,	/* ATA-8 and later */
 	ATA_ID_CAPABILITY	= 49,
 	ATA_ID_OLD_PIO_MODES	= 51,
 	ATA_ID_OLD_DMA_MODES	= 52,
@@ -889,6 +890,13 @@ static inline bool ata_id_has_dword_io(const u16 *id)
 	return id[ATA_ID_DWORD_IO] & (1 << 0);
 }
 
+static inline bool ata_id_has_trusted(const u16 *id)
+{
+	if (ata_id_major_version(id) <= 7)
+		return false;
+	return id[ATA_ID_TRUSTED] & (1 << 0);
+}
+
 static inline bool ata_id_has_unload(const u16 *id)
 {
 	if (ata_id_major_version(id) >= 7 &&