tpm: cmd_ready command can be issued only after granting locality

The correct sequence is to first request locality and only after
that perform cmd_ready handshake, otherwise the hardware will drop
the subsequent message as from the device point of view the cmd_ready
handshake wasn't performed. Symmetrically locality has to be relinquished
only after going idle handshake has completed, this requires that
go_idle has to poll for the completion and as well locality
relinquish has to poll for completion so it is not overridden
in back to back commands flow.

Two wrapper functions are added (request_locality relinquish_locality)
to simplify the error handling.

The issue is only visible on devices that support multiple localities.

Fixes: 877c57d0d0ca ("tpm_crb: request and relinquish locality 0")
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkine@linux.intel.com>
Tested-by: Jarkko Sakkinen <jarkko.sakkine@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkine@linux.intel.com>

1 files changed, 41 insertions, 13 deletions

diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 9e80a95..d27a7fb 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -369,6 +369,36 @@ err_len:
 	return -EINVAL;
 }
 
+static int tpm_request_locality(struct tpm_chip *chip)
+{
+	int rc;
+
+	if (!chip->ops->request_locality)
+		return 0;
+
+	rc = chip->ops->request_locality(chip, 0);
+	if (rc < 0)
+		return rc;
+
+	chip->locality = rc;
+
+	return 0;
+}
+
+static void tpm_relinquish_locality(struct tpm_chip *chip)
+{
+	int rc;
+
+	if (!chip->ops->relinquish_locality)
+		return;
+
+	rc = chip->ops->relinquish_locality(chip, chip->locality);
+	if (rc)
+		dev_err(&chip->dev, "%s: : error %d\n", __func__, rc);
+
+	chip->locality = -1;
+}
+
 /**
  * tmp_transmit - Internal kernel interface to transmit TPM commands.
  *
@@ -422,8 +452,6 @@ ssize_t tpm_transmit(struct tpm_chip *chip, struct tpm_space *space,
 	if (!(flags & TPM_TRANSMIT_UNLOCKED))
 		mutex_lock(&chip->tpm_mutex);
 
-	if (chip->dev.parent)
-		pm_runtime_get_sync(chip->dev.parent);
 
 	if (chip->ops->clk_enable != NULL)
 		chip->ops->clk_enable(chip, true);
@@ -431,14 +459,15 @@ ssize_t tpm_transmit(struct tpm_chip *chip, struct tpm_space *space,
 	/* Store the decision as chip->locality will be changed. */
 	need_locality = chip->locality == -1;
 
-	if (!(flags & TPM_TRANSMIT_RAW) &&
-	    need_locality && chip->ops->request_locality)  {
-		rc = chip->ops->request_locality(chip, 0);
+	if (!(flags & TPM_TRANSMIT_RAW) && need_locality) {
+		rc = tpm_request_locality(chip);
 		if (rc < 0)
 			goto out_no_locality;
-		chip->locality = rc;
 	}
 
+	if (chip->dev.parent)
+		pm_runtime_get_sync(chip->dev.parent);
+
 	rc = tpm2_prepare_space(chip, space, ordinal, buf);
 	if (rc)
 		goto out;
@@ -499,17 +528,16 @@ out_recv:
 	rc = tpm2_commit_space(chip, space, ordinal, buf, &len);
 
 out:
-	if (need_locality && chip->ops->relinquish_locality) {
-		chip->ops->relinquish_locality(chip, chip->locality);
-		chip->locality = -1;
-	}
+	if (chip->dev.parent)
+		pm_runtime_put_sync(chip->dev.parent);
+
+	if (need_locality)
+		tpm_relinquish_locality(chip);
+
 out_no_locality:
 	if (chip->ops->clk_enable != NULL)
 		chip->ops->clk_enable(chip, false);
 
-	if (chip->dev.parent)
-		pm_runtime_put_sync(chip->dev.parent);
-
 	if (!(flags & TPM_TRANSMIT_UNLOCKED))
 		mutex_unlock(&chip->tpm_mutex);
 	return rc ? rc : len;