[S] Change in coreboot[master]: drivers/spi/tpm: Wait for STS_COMMAND_READY

[Yu-Ping Wu (Code Review)]

Yu-Ping Wu has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/71724 )

Change subject: drivers/spi/tpm: Wait for STS_COMMAND_READY
......................................................................

drivers/spi/tpm: Wait for STS_COMMAND_READY

If we reset Ti50 in the middle of a command, it will not become ready
for the 1st command after reboot until the TPM app returns the buffer
from the previously ongoing command. Therefore, add a loop to retry
writing TPM_STS_COMMAND_READY to STS register.

BUG=b:263531882
TEST=emerge-corsola coreboot
BRANCH=none

Change-Id: I06fd8f400622f6b9afea520cec19ea962ebe8568
Signed-off-by: Yu-Ping Wu 
---
M src/drivers/spi/tpm/tpm.c
1 file changed, 42 insertions(+), 5 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/24/71724/1

diff --git a/src/drivers/spi/tpm/tpm.c b/src/drivers/spi/tpm/tpm.c
index 976a8d8..050edd3 100644
--- a/src/drivers/spi/tpm/tpm.c
+++ b/src/drivers/spi/tpm/tpm.c
@@ -604,6 +604,7 @@
    uint8_t *rsp_body = tpm2_response;
    union fifo_transfer_buffer fifo_buffer;
    const int HEADER_SIZE = 6;
+	struct stopwatch sw;

/* Do not try using an uninitialized TPM. */
    if (!tpm_info.vendor_id)
@@ -622,11 +623,28 @@
    	return 0;
    }

-	/* Let the TPM know that the command is coming. */
-	if (write_tpm_sts(TPM_STS_COMMAND_READY) != CB_SUCCESS) {
-		printk(BIOS_ERR, "TPM_STS_COMMAND_READY failed\n");
-		return 0;
-	}
+	/*
+	 * Let the TPM know that the command is coming.
+	 *
+	 * If we reset Ti50 in the middle of a command, it will not become ready for the 1st
+	 * command after reboot until the TPM app returns the buffer from the previously ongoing
+	 * command.
+	 */
+	expected_status_bits = TPM_STS_VALID | TPM_STS_COMMAND_READY;
+	stopwatch_init_usecs_expire(&sw, 1000);
+	status = 0;
+	do {
+		enum cb_err ret = write_tpm_sts(TPM_STS_COMMAND_READY);
+		udelay(10);
+		if (ret == CB_SUCCESS)
+			read_tpm_sts(&status);
+		else
+			printk(BIOS_WARNING, "failed to write TPM_STS_COMMAND_READY\n");
+		if (stopwatch_expired(&sw)) {
+			printk(BIOS_ERR, "timeout waiting for TPM_STS_COMMAND_READY\n");
+			return 0;
+		}
+	} while (!(status & expected_status_bits));

/*
     * TPM commands and responses written to and read from the FIFO