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tpm: i2c: When probing the TPM, write a 0 into the TPM access register.

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Not doing so makes it fail when run at high frequency.

BUG=chrome-os-partner:27220
TEST=Built and booted on nyan with EFS and with the TPM turned up to 400 KHz.
BRANCH=None

Change-Id: I1cfb69c55f03cb90f66f437289803d897a1aad5c
Signed-off-by: Gabe Black <gabeblack@google.com>
Reviewed-on: https://chromium-review.googlesource.com/191812
Reviewed-by: Tom Warren <twarren@nvidia.com>
Reviewed-by: Jimmy Zhang <jimmzhang@nvidia.com>
Reviewed-by: David Hendricks <dhendrix@chromium.org>
Tested-by: Tom Warren <twarren@nvidia.com>
Commit-Queue: Gabe Black <gabeblack@chromium.org>
This commit is contained in:
Gabe Black 2014-03-26 21:51:41 -07:00 • committed by chrome-internal-fetch
commit 04452441d2
1 changed files with 3 additions and 3 deletions
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6
src/drivers/i2c/tpm/tis.c
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@ -79,10 +79,10 @@ int tis_init(void)
* Probe TPM twice; the first probing might fail because TPM is asleep,
* and the probing can wake up TPM.
*/
uint8_t tmp;
uint8_t tmp = 0;
if (i2c_read(bus, chip, 0, 0, &tmp, sizeof(tmp)) &&
i2c_read(bus, chip, 0, 0, &tmp, sizeof(tmp)))
if (i2c_write(bus, chip, 0, 1, &tmp, sizeof(tmp)) &&
i2c_write(bus, chip, 0, 1, &tmp, sizeof(tmp)))
return -1;
return 0;