[PATCH v2 2/2] tpm: Add field upgrade mode support for Infineon TPM2 modules

[Stefan Mahnke-Hartmann <stefan.mahnke-hartmann@infineon.com>]

TPM2_GetCapability with a capability that has the property type value
of TPM_PT_TOTAL_COMMANDS returns a zero length list, when an Infineon
TPM2 is in field upgrade mode.
Since an Infineon TPM2.0 in field upgrade mode returns RC_SUCCESS on
TPM2_Startup, the field upgrade mode has to be detected by
TPM2_GetCapability.

Signed-off-by: Stefan Mahnke-Hartmann <stefan.mahnke-hartmann@infineon.com>
---
Changelog:
 * v2:
   * Move check of -ENODATA to if condition below.
   * Change 'field upgrade mode' to lower case.

 drivers/char/tpm/tpm2-cmd.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 04a3e23a4afc..c1eb5d223839 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -754,7 +754,11 @@ int tpm2_auto_startup(struct tpm_chip *chip)
 	rc = tpm2_get_cc_attrs_tbl(chip);
 
 out:
-	if (rc == TPM2_RC_UPGRADE) {
+	/*
+	 * Infineon TPM in field upgrade mode will return no data for the number
+	 * of supported commands.
+	 */
+	if (rc == TPM2_RC_UPGRADE || rc == -ENODATA) {
 		dev_info(&chip->dev, "TPM in field upgrade mode, requires firmware upgrade\n");
 		chip->flags |= TPM_CHIP_FLAG_FIRMWARE_UPGRADE;
 		rc = 0;
-- 
2.25.1