tpm_i2c_nuvoton: work out the polling time using mftb()

Currently, the polling time is calculated by adding the sleep time to it.

This calculates the polling time by taking timestamps with mftb() before
calling the i2c-interface to send an i2c request to the tpm. Thus having
a much more accurate polling time.

Signed-off-by: Claudio Carvalho <cclaudio@linux.vnet.ibm.com>
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>

libstb/drivers/tpm_i2c_nuvoton.c

@@ -79,11 +79,15 @@ static bool tpm_check_status(uint8_t status, uint8_t mask, uint8_t expected)
 
 static int tpm_wait_for_command_ready(void)
 {
-	int rc, delay;
+	uint64_t start, stop, now;
+	int rc;
 	uint8_t status;
 
-	for (delay = 0; delay < TPM_TIMEOUT_B;
-	     delay += TPM_TIMEOUT_INTERVAL) {
+	start = mftb();
+	stop = start + msecs_to_tb(TPM_TIMEOUT_B);
+
+	do {
+		now = mftb();
 		rc = tpm_status_read_byte(TPM_STS, &status);
 		if (rc < 0) {
 			/**
@@ -99,12 +103,16 @@ static int tpm_wait_for_command_ready(void)
 		if (tpm_check_status(status,
 				     TPM_STS_COMMAND_READY,
 				     TPM_STS_COMMAND_READY)) {
-			DBG("--- Command ready, delay=%d/%d\n",
-			    delay, TPM_TIMEOUT_B);
+			DBG("--- Command ready, delay=%lu/%d\n",
+			    tb_to_msecs(now-start), TPM_TIMEOUT_B);
 			return 0;
 		}
-		time_wait_ms(TPM_TIMEOUT_INTERVAL);
-	}
+		if (tb_compare(now, stop) == TB_ABEFOREB)
+			time_wait_ms(TPM_TIMEOUT_INTERVAL);
+		else
+			break;
+	} while (1);
+
 	return STB_TPM_TIMEOUT;
 }
 
@@ -173,12 +181,15 @@ static int tpm_wait_for_fifo_status(uint8_t mask, uint8_t expected)
 
 static int tpm_wait_for_data_avail(void)
 {
-	int delay, rc;
+	uint64_t start, stop, now;
 	uint8_t status;
+	int rc;
 
-	for (delay = 0; delay < TPM_TIMEOUT_A;
-	     delay += TPM_TIMEOUT_INTERVAL) {
+	start = mftb();
+	stop = start + msecs_to_tb(TPM_TIMEOUT_A);
 
+	do {
+		now = mftb();
 		rc = tpm_status_read_byte(TPM_STS, &status);
 		if (rc < 0) {
 			/**
@@ -194,36 +205,43 @@ static int tpm_wait_for_data_avail(void)
 		if (tpm_check_status(status,
 				     TPM_STS_VALID | TPM_STS_DATA_AVAIL,
 				     TPM_STS_VALID | TPM_STS_DATA_AVAIL)) {
-			DBG("---- read FIFO. Data available. delay=%d/%d\n",
-			    delay, TPM_TIMEOUT_A);
+			DBG("---- Data available. delay=%lu/%d\n",
+			    tb_to_msecs(now-start), TPM_TIMEOUT_A);
 			return 0;
 		}
-		time_wait_ms(TPM_TIMEOUT_INTERVAL);
-	}
+		if (tb_compare(now, stop) == TB_ABEFOREB)
+			time_wait_ms(TPM_TIMEOUT_INTERVAL);
+		else
+			break;
+	} while (1);
 	/**
 	 * @fwts-label TPMDataAvailBitTimeout
 	 * @fwts-advice The data avail bit of the tpm status register is taking
 	 * longer to be settled. Either the wait time need to be increased or
 	 * the TPM device is not functional.
 	 */
-	prlog(PR_ERR, "NUVOTON: timeout on sts.dataAvail, delay=%d/%d\n",
-	      delay, TPM_TIMEOUT_A);
+	prlog(PR_ERR, "NUVOTON: timeout on sts.dataAvail, delay=%lu/%d\n",
+	      tb_to_msecs(now-start), TPM_TIMEOUT_A);
 	return STB_TPM_TIMEOUT;
 }
 
 static int tpm_read_burst_count(void)
 {
-	int rc, delay;
+	uint64_t start, stop, now;
 	uint8_t burst_count;
+	int rc;
 
+	start = mftb();
+	stop = start + msecs_to_tb(TPM_TIMEOUT_D);
 	burst_count = 0;
-	delay = 0;
+
 	do {
+		now = mftb();
 		/* In i2C, burstCount is 1 byte */
 		rc = tpm_status_read_byte(TPM_BURST_COUNT, &burst_count);
 		if (rc == 0 && burst_count > 0) {
-			DBG("---- burst_count=%d, delay=%d/%d\n", burst_count,
-			    delay, TPM_TIMEOUT_D);
+			DBG("---- burst_count=%d, delay=%lu/%d\n", burst_count,
+			    tb_to_msecs(now-start), TPM_TIMEOUT_D);
 			return (int) burst_count;
 		}
 		if (rc < 0) {
@@ -237,19 +255,20 @@ static int tpm_read_burst_count(void)
 			      "rc=%d\n", rc);
 			return STB_DRIVER_ERROR;
 		}
-		time_wait_ms(TPM_TIMEOUT_INTERVAL);
-		delay += TPM_TIMEOUT_INTERVAL;
-
-	} while (delay < TPM_TIMEOUT_D);
+		if (tb_compare(now, stop) == TB_ABEFOREB)
+			time_wait_ms(TPM_TIMEOUT_INTERVAL);
+		else
+			break;
+	} while (1);
 
 	/**
 	 * @fwts-label TPMBurstCountTimeout
 	 * @fwts-advice The burstcount bit of the tpm status register is
 	 * taking longer to be settled. Either the wait time need to be
 	 * increased or the TPM device is not functional.
 	 */
-	prlog(PR_ERR, "NUVOTON: timeout on sts.burstCount, delay=%d/%d\n",
-	      delay, TPM_TIMEOUT_D);
+	prlog(PR_ERR, "NUVOTON: timeout on sts.burstCount, delay=%lu/%d\n",
+	      tb_to_msecs(now-start), TPM_TIMEOUT_D);
 	return STB_TPM_TIMEOUT;
 }