[coreboot-gerrit] Change in coreboot[master]: [DONOTSUBMIT] drivers/pc80/tpm: Poll VID and DID.

[Masanori Ogino (Code Review)]

Masanori Ogino has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/45442 )

Change subject: [DONOTSUBMIT] drivers/pc80/tpm: Poll VID and DID.
......................................................................

[DONOTSUBMIT] drivers/pc80/tpm: Poll VID and DID.

Signed-off-by: Masanori Ogino 
Change-Id: I49000b9dd5560e8a36c925b3ad1dbfc78d6c14af
---
M src/drivers/pc80/tpm/tis.c
1 file changed, 14 insertions(+), 3 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/42/45442/1

diff --git a/src/drivers/pc80/tpm/tis.c b/src/drivers/pc80/tpm/tis.c
index 27d238c..c03bc90 100644
--- a/src/drivers/pc80/tpm/tis.c
+++ b/src/drivers/pc80/tpm/tis.c
@@ -80,7 +80,7 @@
  * so this value is a safe error indication to be mixed with possible status
  * register values.
  */
-#define TPM_TIMEOUT_ERR			(~0)
+#define TPM_TIMEOUT_ERR		(~0)

/* Error value returned on various TPM driver errors */
 #define TPM_DRIVER_ERR		(~0)
@@ -386,6 +386,7 @@
    const char *device_name = "unknown";
    const char *vendor_name = device_name;
    const struct device_name *dev;
+	u32 time_us = MAX_DELAY_US;
    u32 didvid;
    u16 vid, did;
    int i;
@@ -393,8 +394,18 @@
    if (vendor_dev_id)
    	return 0;  /* Already probed. */

-	didvid = tpm_read_did_vid(0);
-	if (!didvid || (didvid == 0xffffffff)) {
+	do {
+		const u32 delay = 100; /* microseconds */
+		didvid = tpm_read_did_vid(0);
+
+		if (didvid != 0x00000000 && didvid != 0xffffffff)
+			break;
+
+		udelay(delay);
+		time_us -= delay;
+	} while (time_us > 0);
+
+	if (didvid == 0x00000000 || didvid == 0xffffffff) {
    	printf("%s: No TPM device found\n", __func__);
    	return TPM_DRIVER_ERR;
    }