[PATCH REVIEW 1/2] tpm: provide a way to override the chip returned durations

[Alexey Klimov <aklimov@redhat.com>]

Patch adds method ->update_durations to override returned
durations in case TPM chip misbehaves for TPM 1.2 drivers.

Cc: Jerry Snitselaar <jsnitsel@redhat.com>
Signed-off-by: Alexey Klimov <aklimov@redhat.com>
---
 drivers/char/tpm/tpm-interface.c | 18 ++++++++++++++++++
 include/linux/tpm.h              |  2 ++
 2 files changed, 20 insertions(+)

diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 129f640424b7..5cb90918938d 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -768,6 +768,7 @@ int tpm_get_timeouts(struct tpm_chip *chip)
 {
 	cap_t cap;
 	unsigned long timeout_old[4], timeout_chip[4], timeout_eff[4];
+	unsigned long durations[3];
 	ssize_t rc;
 
 	if (chip->flags & TPM_CHIP_FLAG_HAVE_TIMEOUTS)
@@ -877,6 +878,23 @@ int tpm_get_timeouts(struct tpm_chip *chip)
 		usecs_to_jiffies(be32_to_cpu(cap.duration.tpm_long));
 	chip->duration[TPM_LONG_LONG] = 0; /* not used under 1.2 */
 
+	/*
+	 * Provide ability for vendor overrides of duration values in case
+	 * of misreporting.
+	 */
+	if (chip->ops->update_durations != NULL)
+		chip->duration_adjusted =
+			chip->ops->update_durations(chip, durations);
+
+	/* Report and set adjusted timeouts */
+	if (chip->duration_adjusted) {
+
+		dev_info(&chip->dev, HW_ERR "Adjusting reported durations\n");
+		chip->duration[TPM_SHORT] = durations[0];
+		chip->duration[TPM_MEDIUM] = durations[1];
+		chip->duration[TPM_LONG] = durations[2];
+	}
+
 	/* The Broadcom BCM0102 chipset in a Dell Latitude D820 gets the above
 	 * value wrong and apparently reports msecs rather than usecs. So we
 	 * fix up the resulting too-small TPM_SHORT value to make things work.
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index 4609b94142d4..d6018431b478 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -43,6 +43,8 @@ struct tpm_class_ops {
 	u8 (*status) (struct tpm_chip *chip);
 	bool (*update_timeouts)(struct tpm_chip *chip,
 				unsigned long *timeout_cap);
+	bool (*update_durations)(struct tpm_chip *chip,
+				unsigned long *durations_cap);
 	int (*go_idle)(struct tpm_chip *chip);
 	int (*cmd_ready)(struct tpm_chip *chip);
 	int (*request_locality)(struct tpm_chip *chip, int loc);
-- 
2.14.4