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tpm_crb: fix crb_req_canceled behavior

Message ID 1464952721-7848-1-git-send-email-jarkko.sakkinen@linux.intel.com (mailing list archive)
State New, archived
Headers show

Commit Message

Jarkko Sakkinen June 3, 2016, 11:18 a.m. UTC
The req_canceled() callback is used by tpm_transmit() periodically to
check whether the request has been canceled while it is receiving a
response from the TPM.

The TPM_CRB_CTRL_CANCEL register was cleared already in the crb_cancel
callback, which has two consequences:

* Cancel might not happen.
* req_canceled() always returns zero.

A better place to clear the register is when starting to send a new
command. The behavior of TPM_CRB_CTRL_CANCEL is described in the
section of the PTP specification.

CC: stable@vger.kernel.org
Fixes: 30fc8d138e91 ("tpm: TPM 2.0 CRB Interface")
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
 drivers/char/tpm/tpm_crb.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)
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diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c
index 1547636..b4d46ae 100644
--- a/drivers/char/tpm/tpm_crb.c
+++ b/drivers/char/tpm/tpm_crb.c
@@ -142,6 +142,11 @@  static int crb_send(struct tpm_chip *chip, u8 *buf, size_t len)
 	struct crb_priv *priv = dev_get_drvdata(&chip->dev);
 	int rc = 0;
+	/* Zero the cancel register so that the next command will not get
+	 * canceled.
+	 */
+	iowrite32(0, &priv->cca->cancel);
 	if (len > ioread32(&priv->cca->cmd_size)) {
 			"invalid command count value %x %zx\n",
@@ -175,8 +180,6 @@  static void crb_cancel(struct tpm_chip *chip)
 	if ((priv->flags & CRB_FL_ACPI_START) && crb_do_acpi_start(chip))
 		dev_err(&chip->dev, "ACPI Start failed\n");
-	iowrite32(0, &priv->cca->cancel);
 static bool crb_req_canceled(struct tpm_chip *chip, u8 status)