tpm: fix suspend/resume paths for TPM 2.0

Fixed suspend/resume paths for TPM 2.0 and consolidated all the
associated code to the tpm_pm_suspend() and tpm_pm_resume()
functions. Resume path should be handled by the firmware, i.e.
Startup(CLEAR) for hibernate and Startup(STATE) for suspend.

There might be some non-PC embedded devices in the future where
Startup() is not the handled by the FW but fixing the code for
those IMHO should be postponed until there is hardware available
to test the fixes although extra Startup in the driver code is
essentially a NOP.

Added Shutdown(CLEAR) to the remove paths of TIS and CRB drivers.
Changed tpm2_shutdown() to a void function because there isn't
much you can do except print an error message if this fails with
a system error.

Fixes: aec04cbdf723 ("tpm: TPM 2.0 FIFO Interface")
Fixes: 30fc8d138e91 ("tpm: TPM 2.0 CRB Interface")
[phuewe: both did send TPM_Shutdown on resume which 'disables' the TPM
and did not send TPM2_Shutdown on teardown which leads some TPM2.0 to
believe there was an attack (no TPM2_Shutdown = no orderly shutdown =
attack)]

Reported-by: Peter Hüwe <PeterHuewe@gmx.de>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Tested-by: Scot Doyle <lkml14@scotdoyle.com>
Reviewed-by: Peter Huewe <peterhuewe@gmx.de>
Signed-off-by: Peter Huewe <peterhuewe@gmx.de>

1 files changed, 4 insertions, 2 deletions

diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index bf53a3771da5..e85d3416d899 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -901,8 +901,10 @@ int tpm_pm_suspend(struct device *dev)
 	if (chip == NULL)
 		return -ENODEV;
 
-	if (chip->flags & TPM_CHIP_FLAG_TPM2)
-		return tpm2_shutdown(chip, TPM2_SU_CLEAR);
+	if (chip->flags & TPM_CHIP_FLAG_TPM2) {
+		tpm2_shutdown(chip, TPM2_SU_STATE);
+		return 0;
+	}
 
 	/* for buggy tpm, flush pcrs with extend to selected dummy */
 	if (tpm_suspend_pcr) {