[tpmdd-devel,3/5] tpm_tis_spi: Check correct byte for wait state indicator

Submitted by Peter.Huewe@infineon.com on Feb. 16, 2017, 4:08 p.m.

Details

Message ID 1487261306-2494-4-git-send-email-peter.huewe@infineon.com
State New
Headers show

Commit Message

Peter.Huewe@infineon.com Feb. 16, 2017, 4:08 p.m.
Wait states are signaled in the last byte received from the TPM in
response to the header, not the first byte. Check rx_buf[3] instead of
rx_buf[0].

Cc: <stable@vger.kernel.org>
Fixes: 0edbfea537d1 ("tpm/tpm_tis_spi: Add support for spi phy")
Signed-off-by: Alexander Steffen <Alexander.Steffen@infineon.com>
Signed-off-by: Peter Huewe <peter.huewe@infineon.com>
---
 drivers/char/tpm/tpm_tis_spi.c | 40 +++++++++++++++++++++-------------------
 1 file changed, 21 insertions(+), 19 deletions(-)

Comments

Christophe Ricard Feb. 17, 2017, 5:09 a.m.
That's is correct, this is a mistake on my side and never saw it :-(.

I guess it was possibly leading to "waste" at least 1 wait state on some 
TPMs.

Wouldn't it be better to merge that with #1 and update the comment 
consequently?


On 16/02/2017 08:08, Peter Huewe wrote:
> Wait states are signaled in the last byte received from the TPM in
> response to the header, not the first byte. Check rx_buf[3] instead of
> rx_buf[0].
>
> Cc: <stable@vger.kernel.org>
> Fixes: 0edbfea537d1 ("tpm/tpm_tis_spi: Add support for spi phy")
> Signed-off-by: Alexander Steffen <Alexander.Steffen@infineon.com>
> Signed-off-by: Peter Huewe <peter.huewe@infineon.com>
> ---
>   drivers/char/tpm/tpm_tis_spi.c | 40 +++++++++++++++++++++-------------------
>   1 file changed, 21 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm_tis_spi.c b/drivers/char/tpm/tpm_tis_spi.c
> index d782b9974c14..16938e2253d2 100644
> --- a/drivers/char/tpm/tpm_tis_spi.c
> +++ b/drivers/char/tpm/tpm_tis_spi.c
> @@ -60,7 +60,7 @@ static int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u8 len,
>   				u8 *buffer, u8 direction)
>   {
>   	struct tpm_tis_spi_phy *phy = to_tpm_tis_spi_phy(data);
> -	int ret, i;
> +	int ret;
>   	struct spi_message m;
>   	struct spi_transfer spi_xfer = {
>   		.tx_buf = phy->tx_buf,
> @@ -85,25 +85,27 @@ static int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u8 len,
>   	if (ret < 0)
>   		goto exit;
>   
> -	phy->tx_buf[0] = 0;
> -
> -	/* According to TCG PTP specification, if there is no TPM present at
> -	 * all, then the design has a weak pull-up on MISO. If a TPM is not
> -	 * present, a pull-up on MISO means that the SB controller sees a 1,
> -	 * and will latch in 0xFF on the read.
> -	 */
> -	for (i = 0; (phy->rx_buf[0] & 0x01) == 0 && i < TPM_RETRY; i++) {
> -		spi_xfer.len = 1;
> -		spi_message_init(&m);
> -		spi_message_add_tail(&spi_xfer, &m);
> -		ret = spi_sync_locked(phy->spi_device, &m);
> -		if (ret < 0)
> +	if ((phy->rx_buf[3] & 0x01) == 0) {
> +		// handle SPI wait states
> +		int i;
> +
> +		phy->tx_buf[0] = 0;
> +
> +		for (i = 0; i < TPM_RETRY; i++) {
> +			spi_xfer.len = 1;
> +			spi_message_init(&m);
> +			spi_message_add_tail(&spi_xfer, &m);
> +			ret = spi_sync_locked(phy->spi_device, &m);
> +			if (ret < 0)
> +				goto exit;
> +			if (phy->rx_buf[0] & 0x01)
> +				break;
> +		}
> +
> +		if (i == TPM_RETRY) {
> +			ret = -ETIMEDOUT;
>   			goto exit;
> -	}
> -
> -	if (i == TPM_RETRY) {
> -		ret = -ETIMEDOUT;
> -		goto exit;
> +		}
>   	}
>   
>   	spi_xfer.cs_change = 0;


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Peter Hüwe Feb. 17, 2017, 7:15 a.m.
Am 17. Februar 2017 06:09:30 MEZ schrieb Christophe Ricard <christophe.ricard@gmail.com>:
>That's is correct, this is a mistake on my side and never saw it :-(.
>
>I guess it was possibly leading to "waste" at least 1 wait state on
>some 
>TPMs.

Unfortunately the 1 for indicating end of waitstates does only appear once so it actually rendered the driver non-functional - atleast with our tpms.


>
>Wouldn't it be better to merge that with #1 and update the comment 
>consequently?

Yes, that's what I wanted to express in the cover letter, logically it makes sense to squash #1 and #3 - but reviewing it merged with #1 is quite hard since it "obfuscates" the problem - since too much stuff moves around.
That's why I decided to split it - for easier review.

Peter


>
>
>On 16/02/2017 08:08, Peter Huewe wrote:
>> Wait states are signaled in the last byte received from the TPM in
>> response to the header, not the first byte. Check rx_buf[3] instead
>of
>> rx_buf[0].
>>
>> Cc: <stable@vger.kernel.org>
>> Fixes: 0edbfea537d1 ("tpm/tpm_tis_spi: Add support for spi phy")
>> Signed-off-by: Alexander Steffen <Alexander.Steffen@infineon.com>
>> Signed-off-by: Peter Huewe <peter.huewe@infineon.com>
>> ---
>>   drivers/char/tpm/tpm_tis_spi.c | 40
>+++++++++++++++++++++-------------------
>>   1 file changed, 21 insertions(+), 19 deletions(-)
>>
>> diff --git a/drivers/char/tpm/tpm_tis_spi.c
>b/drivers/char/tpm/tpm_tis_spi.c
>> index d782b9974c14..16938e2253d2 100644
>> --- a/drivers/char/tpm/tpm_tis_spi.c
>> +++ b/drivers/char/tpm/tpm_tis_spi.c
>> @@ -60,7 +60,7 @@ static int tpm_tis_spi_transfer(struct tpm_tis_data
>*data, u32 addr, u8 len,
>>   				u8 *buffer, u8 direction)
>>   {
>>   	struct tpm_tis_spi_phy *phy = to_tpm_tis_spi_phy(data);
>> -	int ret, i;
>> +	int ret;
>>   	struct spi_message m;
>>   	struct spi_transfer spi_xfer = {
>>   		.tx_buf = phy->tx_buf,
>> @@ -85,25 +85,27 @@ static int tpm_tis_spi_transfer(struct
>tpm_tis_data *data, u32 addr, u8 len,
>>   	if (ret < 0)
>>   		goto exit;
>>   
>> -	phy->tx_buf[0] = 0;
>> -
>> -	/* According to TCG PTP specification, if there is no TPM present
>at
>> -	 * all, then the design has a weak pull-up on MISO. If a TPM is not
>> -	 * present, a pull-up on MISO means that the SB controller sees a
>1,
>> -	 * and will latch in 0xFF on the read.
>> -	 */
>> -	for (i = 0; (phy->rx_buf[0] & 0x01) == 0 && i < TPM_RETRY; i++) {
>> -		spi_xfer.len = 1;
>> -		spi_message_init(&m);
>> -		spi_message_add_tail(&spi_xfer, &m);
>> -		ret = spi_sync_locked(phy->spi_device, &m);
>> -		if (ret < 0)
>> +	if ((phy->rx_buf[3] & 0x01) == 0) {
>> +		// handle SPI wait states
>> +		int i;
>> +
>> +		phy->tx_buf[0] = 0;
>> +
>> +		for (i = 0; i < TPM_RETRY; i++) {
>> +			spi_xfer.len = 1;
>> +			spi_message_init(&m);
>> +			spi_message_add_tail(&spi_xfer, &m);
>> +			ret = spi_sync_locked(phy->spi_device, &m);
>> +			if (ret < 0)
>> +				goto exit;
>> +			if (phy->rx_buf[0] & 0x01)
>> +				break;
>> +		}
>> +
>> +		if (i == TPM_RETRY) {
>> +			ret = -ETIMEDOUT;
>>   			goto exit;
>> -	}
>> -
>> -	if (i == TPM_RETRY) {
>> -		ret = -ETIMEDOUT;
>> -		goto exit;
>> +		}
>>   	}
>>   
>>   	spi_xfer.cs_change = 0;
Jarkko Sakkinen Feb. 24, 2017, 12:57 p.m.
On Thu, Feb 16, 2017 at 04:08:24PM +0000, Peter Huewe wrote:
> Wait states are signaled in the last byte received from the TPM in
> response to the header, not the first byte. Check rx_buf[3] instead of
> rx_buf[0].
> 
> Cc: <stable@vger.kernel.org>
> Fixes: 0edbfea537d1 ("tpm/tpm_tis_spi: Add support for spi phy")
> Signed-off-by: Alexander Steffen <Alexander.Steffen@infineon.com>
> Signed-off-by: Peter Huewe <peter.huewe@infineon.com>

Reviewed-by: Jarkko Sakkien <jarkko.sakkinen@linux.intel.com>

/Jarkko

> ---
>  drivers/char/tpm/tpm_tis_spi.c | 40 +++++++++++++++++++++-------------------
>  1 file changed, 21 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm_tis_spi.c b/drivers/char/tpm/tpm_tis_spi.c
> index d782b9974c14..16938e2253d2 100644
> --- a/drivers/char/tpm/tpm_tis_spi.c
> +++ b/drivers/char/tpm/tpm_tis_spi.c
> @@ -60,7 +60,7 @@ static int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u8 len,
>  				u8 *buffer, u8 direction)
>  {
>  	struct tpm_tis_spi_phy *phy = to_tpm_tis_spi_phy(data);
> -	int ret, i;
> +	int ret;
>  	struct spi_message m;
>  	struct spi_transfer spi_xfer = {
>  		.tx_buf = phy->tx_buf,
> @@ -85,25 +85,27 @@ static int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u8 len,
>  	if (ret < 0)
>  		goto exit;
>  
> -	phy->tx_buf[0] = 0;
> -
> -	/* According to TCG PTP specification, if there is no TPM present at
> -	 * all, then the design has a weak pull-up on MISO. If a TPM is not
> -	 * present, a pull-up on MISO means that the SB controller sees a 1,
> -	 * and will latch in 0xFF on the read.
> -	 */
> -	for (i = 0; (phy->rx_buf[0] & 0x01) == 0 && i < TPM_RETRY; i++) {
> -		spi_xfer.len = 1;
> -		spi_message_init(&m);
> -		spi_message_add_tail(&spi_xfer, &m);
> -		ret = spi_sync_locked(phy->spi_device, &m);
> -		if (ret < 0)
> +	if ((phy->rx_buf[3] & 0x01) == 0) {
> +		// handle SPI wait states
> +		int i;
> +
> +		phy->tx_buf[0] = 0;
> +
> +		for (i = 0; i < TPM_RETRY; i++) {
> +			spi_xfer.len = 1;
> +			spi_message_init(&m);
> +			spi_message_add_tail(&spi_xfer, &m);
> +			ret = spi_sync_locked(phy->spi_device, &m);
> +			if (ret < 0)
> +				goto exit;
> +			if (phy->rx_buf[0] & 0x01)
> +				break;
> +		}
> +
> +		if (i == TPM_RETRY) {
> +			ret = -ETIMEDOUT;
>  			goto exit;
> -	}
> -
> -	if (i == TPM_RETRY) {
> -		ret = -ETIMEDOUT;
> -		goto exit;
> +		}
>  	}
>  
>  	spi_xfer.cs_change = 0;
> -- 
> 2.7.4
> 

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diff --git a/drivers/char/tpm/tpm_tis_spi.c b/drivers/char/tpm/tpm_tis_spi.c
index d782b9974c14..16938e2253d2 100644
--- a/drivers/char/tpm/tpm_tis_spi.c
+++ b/drivers/char/tpm/tpm_tis_spi.c
@@ -60,7 +60,7 @@  static int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u8 len,
 				u8 *buffer, u8 direction)
 {
 	struct tpm_tis_spi_phy *phy = to_tpm_tis_spi_phy(data);
-	int ret, i;
+	int ret;
 	struct spi_message m;
 	struct spi_transfer spi_xfer = {
 		.tx_buf = phy->tx_buf,
@@ -85,25 +85,27 @@  static int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u8 len,
 	if (ret < 0)
 		goto exit;
 
-	phy->tx_buf[0] = 0;
-
-	/* According to TCG PTP specification, if there is no TPM present at
-	 * all, then the design has a weak pull-up on MISO. If a TPM is not
-	 * present, a pull-up on MISO means that the SB controller sees a 1,
-	 * and will latch in 0xFF on the read.
-	 */
-	for (i = 0; (phy->rx_buf[0] & 0x01) == 0 && i < TPM_RETRY; i++) {
-		spi_xfer.len = 1;
-		spi_message_init(&m);
-		spi_message_add_tail(&spi_xfer, &m);
-		ret = spi_sync_locked(phy->spi_device, &m);
-		if (ret < 0)
+	if ((phy->rx_buf[3] & 0x01) == 0) {
+		// handle SPI wait states
+		int i;
+
+		phy->tx_buf[0] = 0;
+
+		for (i = 0; i < TPM_RETRY; i++) {
+			spi_xfer.len = 1;
+			spi_message_init(&m);
+			spi_message_add_tail(&spi_xfer, &m);
+			ret = spi_sync_locked(phy->spi_device, &m);
+			if (ret < 0)
+				goto exit;
+			if (phy->rx_buf[0] & 0x01)
+				break;
+		}
+
+		if (i == TPM_RETRY) {
+			ret = -ETIMEDOUT;
 			goto exit;
-	}
-
-	if (i == TPM_RETRY) {
-		ret = -ETIMEDOUT;
-		goto exit;
+		}
 	}
 
 	spi_xfer.cs_change = 0;