[coreboot-gerrit] Change in coreboot[master]: drivers/i2c/tpm/cr50.c: Check if TPM was read

[Richard Spiegel (Code Review)]

Richard Spiegel has uploaded this change for review. ( https://review.coreboot.org/27995

Change subject: drivers/i2c/tpm/cr50.c: Check if TPM was read
......................................................................

drivers/i2c/tpm/cr50.c: Check if TPM was read

Under some conditions, cr50_i2c_read() can return without actually reading
the TPM, which will leave access uninitialized. Set an initial value for
access, and if TPM fails to respond in time check if at least TPM was read.
This way avoids printing an uninitialized value.

BUG=b:112253891
TEST=Build and boot grunt.

Change-Id: I5ec7a99396db32971dc8485b77158d735ab1d788
Signed-off-by: Richard Spiegel 
---
M src/drivers/i2c/tpm/cr50.c
1 file changed, 7 insertions(+), 4 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/95/27995/1

diff --git a/src/drivers/i2c/tpm/cr50.c b/src/drivers/i2c/tpm/cr50.c
index 3c2f5bd..036be42 100644
--- a/src/drivers/i2c/tpm/cr50.c
+++ b/src/drivers/i2c/tpm/cr50.c
@@ -181,7 +181,7 @@
 static int process_reset(struct tpm_chip *chip)
 {
    struct stopwatch sw;
-	uint8_t access;
+	uint8_t access = 0xff;

/*
     * Locality is released by TPM reset.
@@ -214,9 +214,12 @@
    	return 0;
    } while (!stopwatch_expired(&sw));

-	printk(BIOS_ERR,
-	       "TPM failed to reset after %ld ms, status: %#x\n",
-	       stopwatch_duration_msecs(&sw), access);
+	if (access == 0xff)
+		printk(BIOS_ERR, "Failed to read TPM\n");
+	else
+		printk(BIOS_ERR,
+			"TPM failed to reset after %ld ms, status: %#x\n",
+			stopwatch_duration_msecs(&sw), access);

return -1;
 }