linux-kernel - [PATCH] tpm, tpm_crb: remove redundant CRB_FL_CRB

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Date:   Mon, 17 Oct 2016 23:42:24 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     tpmdd-devel@...ts.sourceforge.net
Cc:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        Peter Huewe <peterhuewe@....de>,
        Marcel Selhorst <tpmdd@...horst.net>,
        Jason Gunthorpe <jgunthorpe@...idianresearch.com>,
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH] tpm, tpm_crb: remove redundant CRB_FL_CRB_START flag

Because all the existing hardware have HID MSFT0101 we end up always
setting CRB_FL_CRB_START flag as a workaround for 4th Gen Core CPUs.
Even if ACPI start is used, the driver will always issue also CRB start.

This commit makes the invocation of CRB start unconditional.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
---
 drivers/char/tpm/tpm_crb.c | 16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c
index 65040d7..5928ec8 100644
--- a/drivers/char/tpm/tpm_crb.c
+++ b/drivers/char/tpm/tpm_crb.c
@@ -72,7 +72,6 @@ enum crb_status {
 
 enum crb_flags {
 	CRB_FL_ACPI_START	= BIT(0),
-	CRB_FL_CRB_START	= BIT(1),
 };
 
 struct crb_priv {
@@ -226,8 +225,11 @@ static int crb_send(struct tpm_chip *chip, u8 *buf, size_t len)
 	/* Make sure that cmd is populated before issuing start. */
 	wmb();
 
-	if (priv->flags & CRB_FL_CRB_START)
-		iowrite32(CRB_START_INVOKE, &priv->cca->start);
+
+	/* At least some of the 4th Gen Core CPUs that report only needing ACPI
+	 * start require also CRB start so we always set it just in case.
+	 */
+	iowrite32(CRB_START_INVOKE, &priv->cca->start);
 
 	if (priv->flags & CRB_FL_ACPI_START)
 		rc = crb_do_acpi_start(chip);
@@ -407,14 +409,6 @@ static int crb_acpi_add(struct acpi_device *device)
 	if (!priv)
 		return -ENOMEM;
 
-	/* The reason for the extra quirk is that the PTT in 4th Gen Core CPUs
-	 * report only ACPI start but in practice seems to require both
-	 * ACPI start and CRB start.
-	 */
-	if (sm == ACPI_TPM2_COMMAND_BUFFER || sm == ACPI_TPM2_MEMORY_MAPPED ||
-	    !strcmp(acpi_device_hid(device), "MSFT0101"))
-		priv->flags |= CRB_FL_CRB_START;
-
 	if (sm == ACPI_TPM2_START_METHOD ||
 	    sm == ACPI_TPM2_COMMAND_BUFFER_WITH_START_METHOD)
 		priv->flags |= CRB_FL_ACPI_START;
-- 
2.9.3