libata: check for trusted computing in IDENTIFY DEVICE data

[Christoph Hellwig]

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.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
 drivers/ata/libata-core.c |  3 +++
 include/linux/ata.h       | 10 +++++++++-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 697f5f896b19..ca57b03ab950 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -2413,6 +2413,9 @@ static void ata_dev_config_trusted(struct ata_device *dev)
 	u64 trusted_cap;
 	unsigned int err;
 
+	if (!ata_id_has_trusted(dev->id))
+		return;
+
 	if (!ata_identify_page_supported(dev, ATA_LOG_SECURITY)) {
 		ata_dev_warn(dev,
 			     "Security Log not supported\n");
diff --git a/include/linux/ata.h b/include/linux/ata.h
index e65ae4b2ed48..c7a353825450 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 &&
-- 
2.11.0