[v1,3/5] char: tpm: rewrite "tpm_tis_req_canceled()"
diff mbox series

Message ID 20191110162137.230913-4-amirmizi6@gmail.com
State Superseded
Headers show
Series
  • add tpm i2c ptp driver
Related show

Commit Message

Amir Mizinski Nov. 10, 2019, 4:21 p.m. UTC
From: Amir Mizinski <amirmizi6@gmail.com>

using this function while read/write data resulted in aborted operation.
after investigating according to TCG TPM Profile (PTP) Specifications,
i found cancel should happen only if TPM_STS.commandReady bit is lit
and couldn't find a case when the current condition is valid.
also only cmdReady bit need to be compared instead of the full lower status register byte.

Signed-off-by: Amir Mizinski <amirmizi6@gmail.com>
---
 drivers/char/tpm/tpm_tis_core.c | 12 +-----------
 1 file changed, 1 insertion(+), 11 deletions(-)

Comments

Jerry Snitselaar Nov. 10, 2019, 6 p.m. UTC | #1
On Sun Nov 10 19, amirmizi6@gmail.com wrote:
>From: Amir Mizinski <amirmizi6@gmail.com>
>
>using this function while read/write data resulted in aborted operation.
>after investigating according to TCG TPM Profile (PTP) Specifications,
>i found cancel should happen only if TPM_STS.commandReady bit is lit
>and couldn't find a case when the current condition is valid.
>also only cmdReady bit need to be compared instead of the full lower status register byte.
>
>Signed-off-by: Amir Mizinski <amirmizi6@gmail.com>
>---
> drivers/char/tpm/tpm_tis_core.c | 12 +-----------
> 1 file changed, 1 insertion(+), 11 deletions(-)
>
>diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
>index ce7f8a1..9016f06 100644
>--- a/drivers/char/tpm/tpm_tis_core.c
>+++ b/drivers/char/tpm/tpm_tis_core.c
>@@ -627,17 +627,7 @@ static int probe_itpm(struct tpm_chip *chip)
>
> static bool tpm_tis_req_canceled(struct tpm_chip *chip, u8 status)
> {
>-	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
>-
>-	switch (priv->manufacturer_id) {
>-	case TPM_VID_WINBOND:
>-		return ((status == TPM_STS_VALID) ||
>-			(status == (TPM_STS_VALID | TPM_STS_COMMAND_READY)));
>-	case TPM_VID_STM:
>-		return (status == (TPM_STS_VALID | TPM_STS_COMMAND_READY));

Stefan were these cases you found that were deviating from the spec? Wondering
if dropping these will cause issues for these devices.

>-	default:
>-		return (status == TPM_STS_COMMAND_READY);
>-	}
>+	return ((status & TPM_STS_COMMAND_READY) == TPM_STS_COMMAND_READY);
> }
>
> static irqreturn_t tis_int_handler(int dummy, void *dev_id)
>-- 
>2.7.4
>
Stefan Berger Nov. 12, 2019, 1:25 a.m. UTC | #2
On 11/10/19 1:00 PM, Jerry Snitselaar wrote:
> On Sun Nov 10 19, amirmizi6@gmail.com wrote:
>> From: Amir Mizinski <amirmizi6@gmail.com>
>>
>> using this function while read/write data resulted in aborted operation.
>> after investigating according to TCG TPM Profile (PTP) Specifications,
>> i found cancel should happen only if TPM_STS.commandReady bit is lit
>> and couldn't find a case when the current condition is valid.
>> also only cmdReady bit need to be compared instead of the full lower 
>> status register byte.
>>
>> Signed-off-by: Amir Mizinski <amirmizi6@gmail.com>
>> ---
>> drivers/char/tpm/tpm_tis_core.c | 12 +-----------
>> 1 file changed, 1 insertion(+), 11 deletions(-)
>>
>> diff --git a/drivers/char/tpm/tpm_tis_core.c 
>> b/drivers/char/tpm/tpm_tis_core.c
>> index ce7f8a1..9016f06 100644
>> --- a/drivers/char/tpm/tpm_tis_core.c
>> +++ b/drivers/char/tpm/tpm_tis_core.c
>> @@ -627,17 +627,7 @@ static int probe_itpm(struct tpm_chip *chip)
>>
>> static bool tpm_tis_req_canceled(struct tpm_chip *chip, u8 status)
>> {
>> -    struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
>> -
>> -    switch (priv->manufacturer_id) {
>> -    case TPM_VID_WINBOND:
>> -        return ((status == TPM_STS_VALID) ||
>> -            (status == (TPM_STS_VALID | TPM_STS_COMMAND_READY)));
>> -    case TPM_VID_STM:
>> -        return (status == (TPM_STS_VALID | TPM_STS_COMMAND_READY));
>
> Stefan were these cases you found that were deviating from the spec? 
> Wondering
> if dropping these will cause issues for these devices.


I believe these devices needed special handling of the status register 
as they didn't behave as the 'other' devices, so I would expect issues.

    Stefan

Patch
diff mbox series

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index ce7f8a1..9016f06 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -627,17 +627,7 @@  static int probe_itpm(struct tpm_chip *chip)
 
 static bool tpm_tis_req_canceled(struct tpm_chip *chip, u8 status)
 {
-	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
-
-	switch (priv->manufacturer_id) {
-	case TPM_VID_WINBOND:
-		return ((status == TPM_STS_VALID) ||
-			(status == (TPM_STS_VALID | TPM_STS_COMMAND_READY)));
-	case TPM_VID_STM:
-		return (status == (TPM_STS_VALID | TPM_STS_COMMAND_READY));
-	default:
-		return (status == TPM_STS_COMMAND_READY);
-	}
+	return ((status & TPM_STS_COMMAND_READY) == TPM_STS_COMMAND_READY);
 }
 
 static irqreturn_t tis_int_handler(int dummy, void *dev_id)