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From:   amirmizi6@gmail.com
To:     Eyal.Cohen@nuvoton.com, jarkko.sakkinen@linux.intel.com,
        oshrialkoby85@gmail.com, alexander.steffen@infineon.com,
        robh+dt@kernel.org, mark.rutland@arm.com, peterhuewe@gmx.de,
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Cc:     devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-integrity@vger.kernel.org, oshri.alkoby@nuvoton.com,
        tmaimon77@gmail.com, gcwilson@us.ibm.com, kgoldman@us.ibm.com,
        Dan.Morav@nuvoton.com, oren.tanami@nuvoton.com,
        shmulik.hager@nuvoton.com, amir.mizinski@nuvoton.com,
        Amir Mizinski <amirmizi6@gmail.com>
Subject: [PATCH v3 4/7] char: tpm: Fix expected bit handling and send all bytes in one shot without last byte in exception
Date:   Mon, 10 Feb 2020 18:28:35 +0200
Message-Id: <20200210162838.173903-5-amirmizi6@gmail.com>
In-Reply-To: <20200210162838.173903-1-amirmizi6@gmail.com>
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From: Amir Mizinski <amirmizi6@gmail.com>

Today, actual implementation for send massage is not correct. We check and
 loop only on TPM_STS.stsValid bit and next we single check TPM_STS.expect
 bit value.
TPM_STS.expected bit shall be checked in the same time of
 TPM_STS.stsValid, and should be repeated until timeout_A.
To aquire that, "wait_for_tpm_stat" function is modified to
 "wait_for_tpm_stat_result". this function read regulary status register
 and check bit defined by "mask" to reach value defined in "mask_result"
 (that way a bit in mask can be checked if reached 1 or 0).

Respectively, to send message as defined in
 TCG_DesignPrinciples_TPM2p0Driver_vp24_pubrev.pdf, all bytes should be
 sent in one shot instead of sending last byte in exception.

This improvment was suggested by Benoit Houyere.

Signed-off-by: Amir Mizinski <amirmizi6@gmail.com>
---
 drivers/char/tpm/tpm_tis_core.c | 72 ++++++++++++++++-------------------------
 1 file changed, 28 insertions(+), 44 deletions(-)

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 18b9dc4..c8f4cf8 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -44,9 +44,10 @@ static bool wait_for_tpm_stat_cond(struct tpm_chip *chip, u8 mask,
 	return false;
 }
 
-static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask,
-		unsigned long timeout, wait_queue_head_t *queue,
-		bool check_cancel)
+static int wait_for_tpm_stat_result(struct tpm_chip *chip, u8 mask,
+				    u8 mask_result, unsigned long timeout,
+				    wait_queue_head_t *queue,
+				    bool check_cancel)
 {
 	unsigned long stop;
 	long rc;
@@ -55,7 +56,7 @@ static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask,
 
 	/* check current status */
 	status = chip->ops->status(chip);
-	if ((status & mask) == mask)
+	if ((status & mask) == mask_result)
 		return 0;
 
 	stop = jiffies + timeout;
@@ -83,7 +84,7 @@ static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask,
 			usleep_range(TPM_TIMEOUT_USECS_MIN,
 				     TPM_TIMEOUT_USECS_MAX);
 			status = chip->ops->status(chip);
-			if ((status & mask) == mask)
+			if ((status & mask) == mask_result)
 				return 0;
 		} while (time_before(jiffies, stop));
 	}
@@ -290,10 +291,11 @@ static int recv_data(struct tpm_chip *chip, u8 *buf, size_t count)
 	int size = 0, burstcnt, rc;
 
 	while (size < count) {
-		rc = wait_for_tpm_stat(chip,
-				 TPM_STS_DATA_AVAIL | TPM_STS_VALID,
-				 chip->timeout_c,
-				 &priv->read_queue, true);
+		rc = wait_for_tpm_stat_result(chip,
+					TPM_STS_DATA_AVAIL | TPM_STS_VALID,
+					TPM_STS_DATA_AVAIL | TPM_STS_VALID,
+					chip->timeout_c,
+					&priv->read_queue, true);
 		if (rc < 0)
 			return rc;
 		burstcnt = get_burstcount(chip);
@@ -348,8 +350,9 @@ static int tpm_tis_recv(struct tpm_chip *chip, u8 *buf, size_t count)
 			goto out;
 		}
 
-		if (wait_for_tpm_stat(chip, TPM_STS_VALID, chip->timeout_c,
-				      &priv->int_queue, false) < 0) {
+		if (wait_for_tpm_stat_result(chip, TPM_STS_VALID,
+					     TPM_STS_VALID, chip->timeout_c,
+					     &priv->int_queue, false) < 0) {
 			size = -ETIME;
 			goto out;
 		}
@@ -385,61 +388,40 @@ static int tpm_tis_send_data(struct tpm_chip *chip, const u8 *buf, size_t len)
 	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
 	int rc, status, burstcnt;
 	size_t count = 0;
-	bool itpm = priv->flags & TPM_TIS_ITPM_WORKAROUND;
 
 	status = tpm_tis_status(chip);
 	if ((status & TPM_STS_COMMAND_READY) == 0) {
 		tpm_tis_ready(chip);
-		if (wait_for_tpm_stat
-		    (chip, TPM_STS_COMMAND_READY, chip->timeout_b,
-		     &priv->int_queue, false) < 0) {
+		if (wait_for_tpm_stat_result(chip, TPM_STS_COMMAND_READY,
+					     TPM_STS_COMMAND_READY,
+					     chip->timeout_b,
+					     &priv->int_queue, false) < 0) {
 			rc = -ETIME;
 			goto out_err;
 		}
 	}
 
-	while (count < len - 1) {
+	while (count < len) {
 		burstcnt = get_burstcount(chip);
 		if (burstcnt < 0) {
 			dev_err(&chip->dev, "Unable to read burstcount\n");
 			rc = burstcnt;
 			goto out_err;
 		}
-		burstcnt = min_t(int, burstcnt, len - count - 1);
+		burstcnt = min_t(int, burstcnt, len - count);
 		rc = tpm_tis_write_bytes(priv, TPM_DATA_FIFO(priv->locality),
 					 burstcnt, buf + count);
 		if (rc < 0)
 			goto out_err;
 
 		count += burstcnt;
-
-		if (wait_for_tpm_stat(chip, TPM_STS_VALID, chip->timeout_c,
-					&priv->int_queue, false) < 0) {
-			rc = -ETIME;
-			goto out_err;
-		}
-		status = tpm_tis_status(chip);
-		if (!itpm && (status & TPM_STS_DATA_EXPECT) == 0) {
-			rc = -EIO;
-			goto out_err;
-		}
 	}
-
-	/* write last byte */
-	rc = tpm_tis_write8(priv, TPM_DATA_FIFO(priv->locality), buf[count]);
-	if (rc < 0)
-		goto out_err;
-
-	if (wait_for_tpm_stat(chip, TPM_STS_VALID, chip->timeout_c,
-				&priv->int_queue, false) < 0) {
+	if (wait_for_tpm_stat_result(chip, TPM_STS_VALID | TPM_STS_DATA_EXPECT,
+				     TPM_STS_VALID, chip->timeout_c,
+				     &priv->int_queue, false) < 0) {
 		rc = -ETIME;
 		goto out_err;
 	}
-	status = tpm_tis_status(chip);
-	if (!itpm && (status & TPM_STS_DATA_EXPECT) != 0) {
-		rc = -EIO;
-		goto out_err;
-	}
 
 	return 0;
 
@@ -496,9 +478,11 @@ static int tpm_tis_send_main(struct tpm_chip *chip, const u8 *buf, size_t len)
 		ordinal = be32_to_cpu(*((__be32 *) (buf + 6)));
 
 		dur = tpm_calc_ordinal_duration(chip, ordinal);
-		if (wait_for_tpm_stat
-		    (chip, TPM_STS_DATA_AVAIL | TPM_STS_VALID, dur,
-		     &priv->read_queue, false) < 0) {
+		if (wait_for_tpm_stat_result(chip,
+					     TPM_STS_DATA_AVAIL | TPM_STS_VALID,
+					     TPM_STS_DATA_AVAIL | TPM_STS_VALID,
+					     dur,
+					     &priv->read_queue, false) < 0) {
 			rc = -ETIME;
 			goto out_err;
 		}
-- 
2.7.4