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| author | Bill XIE <persmule@gmail.com> | 2018-03-22 17:07:43 +0800 |
|---|---|---|
| committer | Philipp Deppenwiese <zaolin.daisuki@gmail.com> | 2018-04-16 15:47:53 +0000 |
| commit | a4bf0b7cd18595d1ff37ccaa53112cb3b94dc512 (patch) | |
| tree | 3fadac6ebf450ff89aae06428a8a592e613b64a1 /src | |
| parent | c8412ed1f9f1e9fdc0922ba1a3d49db702426814 (diff) | |
| download | coreboot-a4bf0b7cd18595d1ff37ccaa53112cb3b94dc512.tar.xz | |
drivers/pc80/tpm: Add some optional delay to tis_readresponse()
Certain TPMs (observed on Infineon SLB9635 installed on revolve 810 g1)
seem to need some delay between tis_wait_valid() and
tis_has_valid_data(), or tis_has_valid_data() may invalidly return 0,
ending the loop immaturely with some bytes left unread, and fail to
pass the check below, causing the current command not finalized by
tis_command_ready(), and blocking any later tis_wait_ready().
This time the added delay is controlled by a Kconfig option
TPM_RDRESP_NEED_DELAY.
Change-Id: Ic2a2f252e72a0bbce51e2863f8e46647b1570ba5
Signed-off-by: Bill XIE <persmule@gmail.com>
Reviewed-on: https://review.coreboot.org/25322
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Philipp Deppenwiese <zaolin.daisuki@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Diffstat (limited to 'src')
| -rw-r--r-- | src/drivers/pc80/tpm/Kconfig | 9 | ||||
| -rw-r--r-- | src/drivers/pc80/tpm/tis.c | 8 |
2 files changed, 17 insertions, 0 deletions
diff --git a/src/drivers/pc80/tpm/Kconfig b/src/drivers/pc80/tpm/Kconfig index 3bd9083802..879b4a2341 100644 --- a/src/drivers/pc80/tpm/Kconfig +++ b/src/drivers/pc80/tpm/Kconfig @@ -46,3 +46,12 @@ config TPM_DEACTIVATE depends on LPC_TPM help Deactivate TPM by issuing deactivate command. + +config TPM_RDRESP_NEED_DELAY + bool "Enable Delay Workaround for TPM" + default n + depends on LPC_TPM + help + Certain TPMs seem to need some delay when reading response + to work around a race-condition-related issue, possibly + caused by ill-programmed TPM firmware. diff --git a/src/drivers/pc80/tpm/tis.c b/src/drivers/pc80/tpm/tis.c index 9802654ee1..714b7e5ed0 100644 --- a/src/drivers/pc80/tpm/tis.c +++ b/src/drivers/pc80/tpm/tis.c @@ -595,6 +595,14 @@ static u32 tis_readresponse(u8 *buffer, size_t *len) if (offset == expected_count) break; /* We got all we need */ + /* + * Certain TPMs seem to need some delay between tis_wait_valid() + * and tis_has_valid_data(), or some race-condition-related + * issue will occur. + */ + if (IS_ENABLED(CONFIG_TPM_RDRESP_NEED_DELAY)) + udelay(10); + } while (tis_has_valid_data(locality)); /* * Make sure we indeed read all there was. */ |