cr50 i2c: add error message reporting TPM IRQ timeout

Various recent x86 SOCs have trouble registering short pulses
generated by the H1 to indicate that it is ready for the next
transaction.

This patch adds an error message to report this condition, which would
greatly reduce the amount of guesswork when troubleshooting new
platforms.

BUG=b:144002424

TEST=tried this code on the Drallion device exhibiting the problem,
     observed error messages in the coreboot log;

  $ grep IRQ ap.log
  Cr50 i2c TPM IRQ timeout!
  Cr50 i2c TPM IRQ timeout!
  Cr50 i2c TPM IRQ timeout!
  Cr50 i2c TPM IRQ timeout!
  ...

Change-Id: I5f6ee3986bed58e12fd0ec8cecbf35f46c9263c2
Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/37255
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Mathew King <mathewk@chromium.org>

1 files changed, 3 insertions, 2 deletions

diff --git a/src/drivers/i2c/tpm/cr50.c b/src/drivers/i2c/tpm/cr50.c
index 6714bd4a03..f9a286241e 100644
--- a/src/drivers/i2c/tpm/cr50.c
+++ b/src/drivers/i2c/tpm/cr50.c
@@ -78,9 +78,10 @@ static int cr50_i2c_wait_tpm_ready(struct tpm_chip *chip)
 	stopwatch_init_msecs_expire(&sw, CR50_TIMEOUT_IRQ_MS);
 
 	while (!tis_plat_irq_status())
-		if (stopwatch_expired(&sw))
+		if (stopwatch_expired(&sw)) {
+			printk(BIOS_ERR, "Cr50 i2c TPM IRQ timeout!\n");
 			return -1;
-
+		}
 	return 0;
 }