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Subject: Re: [PATCH v4 6/6] tpm, tpm_tis: Only enable supported IRQs
To:     Jarkko Sakkinen <jarkko@kernel.org>
Cc:     peterhuewe@gmx.de, jgg@ziepe.ca, stefanb@linux.vnet.ibm.com,
        linux@mniewoehner.de, linux-integrity@vger.kernel.org,
        linux-kernel@vger.kernel.org, lukas@wunner.de,
        p.rosenberger@kunbus.com, Lino Sanfilippo <l.sanfilippo@kunbus.com>
References: <20220509080559.4381-1-LinoSanfilippo@gmx.de>
 <20220509080559.4381-7-LinoSanfilippo@gmx.de> <YnvRXiMxMRF3mIb8@kernel.org>
From:   Lino Sanfilippo <LinoSanfilippo@gmx.de>
Message-ID: <e5081429-d313-ade2-0dda-b7ac88ebf4f9@gmx.de>
Date:   Wed, 11 May 2022 21:58:00 +0200
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On 11.05.22 at 17:08, Jarkko Sakkinen wrote:
> On Mon, May 09, 2022 at 10:05:59AM +0200, Lino Sanfilippo wrote:
>> From: Lino Sanfilippo <l.sanfilippo@kunbus.com>
>>
>> Instead of blindly trying to enable all possible interrupts, use the re=
sult
>> from the capability query and request only the interrupts that are actu=
ally
>> supported.
>>
>> Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
>> ---
>>  drivers/char/tpm/tpm_tis_core.c | 67 ++++++++++++++++++---------------
>>  drivers/char/tpm/tpm_tis_core.h |  1 +
>>  2 files changed, 37 insertions(+), 31 deletions(-)
>>
>> diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis=
_core.c
>> index 4c65718feb7d..784e153e2895 100644
>> --- a/drivers/char/tpm/tpm_tis_core.c
>> +++ b/drivers/char/tpm/tpm_tis_core.c
>> @@ -976,13 +976,46 @@ int tpm_tis_core_init(struct device *dev, struct =
tpm_tis_data *priv, int irq,
>>  		goto out_err;
>>  	}
>>
>> +	/* Figure out the capabilities */
>> +	rc =3D tpm_tis_read32(priv, TPM_INTF_CAPS(priv->locality), &intfcaps)=
;
>> +	if (rc < 0)
>> +		goto out_err;
>> +
>> +	dev_dbg(dev, "TPM interface capabilities (0x%x):\n",
>> +		intfcaps);
>> +	if (intfcaps & TPM_INTF_BURST_COUNT_STATIC)
>> +		dev_dbg(dev, "\tBurst Count Static\n");
>> +	if (intfcaps & TPM_INTF_CMD_READY_INT) {
>> +		priv->supported_irqs |=3D TPM_INTF_CMD_READY_INT;
>> +		dev_dbg(dev, "\tCommand Ready Int Support\n");
>> +	}
>> +	if (intfcaps & TPM_INTF_INT_EDGE_FALLING)
>> +		dev_dbg(dev, "\tInterrupt Edge Falling\n");
>> +	if (intfcaps & TPM_INTF_INT_EDGE_RISING)
>> +		dev_dbg(dev, "\tInterrupt Edge Rising\n");
>> +	if (intfcaps & TPM_INTF_INT_LEVEL_LOW)
>> +		dev_dbg(dev, "\tInterrupt Level Low\n");
>> +	if (intfcaps & TPM_INTF_INT_LEVEL_HIGH)
>> +		dev_dbg(dev, "\tInterrupt Level High\n");
>> +	if (intfcaps & TPM_INTF_LOCALITY_CHANGE_INT) {
>> +		priv->supported_irqs |=3D TPM_INTF_LOCALITY_CHANGE_INT;
>> +		dev_dbg(dev, "\tLocality Change Int Support\n");
>> +	}
>> +	if (intfcaps & TPM_INTF_STS_VALID_INT) {
>> +		priv->supported_irqs |=3D TPM_INTF_STS_VALID_INT;
>> +		dev_dbg(dev, "\tSts Valid Int Support\n");
>> +	}
>> +	if (intfcaps & TPM_INTF_DATA_AVAIL_INT) {
>> +		priv->supported_irqs |=3D TPM_INTF_DATA_AVAIL_INT;
>> +		dev_dbg(dev, "\tData Avail Int Support\n");
>> +	}
>> +
>>  	/* Take control of the TPM's interrupt hardware and shut it off */
>>  	rc =3D tpm_tis_read32(priv, TPM_INT_ENABLE(priv->locality), &intmask)=
;
>>  	if (rc < 0)
>>  		goto out_err;
>>
>> -	intmask |=3D TPM_INTF_CMD_READY_INT | TPM_INTF_LOCALITY_CHANGE_INT |
>> -		   TPM_INTF_DATA_AVAIL_INT | TPM_INTF_STS_VALID_INT;
>> +	intmask |=3D priv->supported_irqs;
>>  	intmask &=3D ~TPM_GLOBAL_INT_ENABLE;
>>
>>  	tpm_tis_write32(priv, TPM_INT_ENABLE(priv->locality), intmask);
>> @@ -1009,32 +1042,6 @@ int tpm_tis_core_init(struct device *dev, struct=
 tpm_tis_data *priv, int irq,
>>  		goto out_err;
>>  	}
>>
>> -	/* Figure out the capabilities */
>> -	rc =3D tpm_tis_read32(priv, TPM_INTF_CAPS(priv->locality), &intfcaps)=
;
>> -	if (rc < 0)
>> -		goto out_err;
>> -
>> -	dev_dbg(dev, "TPM interface capabilities (0x%x):\n",
>> -		intfcaps);
>> -	if (intfcaps & TPM_INTF_BURST_COUNT_STATIC)
>> -		dev_dbg(dev, "\tBurst Count Static\n");
>> -	if (intfcaps & TPM_INTF_CMD_READY_INT)
>> -		dev_dbg(dev, "\tCommand Ready Int Support\n");
>> -	if (intfcaps & TPM_INTF_INT_EDGE_FALLING)
>> -		dev_dbg(dev, "\tInterrupt Edge Falling\n");
>> -	if (intfcaps & TPM_INTF_INT_EDGE_RISING)
>> -		dev_dbg(dev, "\tInterrupt Edge Rising\n");
>> -	if (intfcaps & TPM_INTF_INT_LEVEL_LOW)
>> -		dev_dbg(dev, "\tInterrupt Level Low\n");
>> -	if (intfcaps & TPM_INTF_INT_LEVEL_HIGH)
>> -		dev_dbg(dev, "\tInterrupt Level High\n");
>> -	if (intfcaps & TPM_INTF_LOCALITY_CHANGE_INT)
>> -		dev_dbg(dev, "\tLocality Change Int Support\n");
>> -	if (intfcaps & TPM_INTF_STS_VALID_INT)
>> -		dev_dbg(dev, "\tSts Valid Int Support\n");
>> -	if (intfcaps & TPM_INTF_DATA_AVAIL_INT)
>> -		dev_dbg(dev, "\tData Avail Int Support\n");
>> -
>>  	/* INTERRUPT Setup */
>>  	init_waitqueue_head(&priv->read_queue);
>>  	init_waitqueue_head(&priv->int_queue);
>> @@ -1101,9 +1108,7 @@ static void tpm_tis_reenable_interrupts(struct tp=
m_chip *chip)
>>  	if (rc < 0)
>>  		goto out;
>>
>> -	intmask |=3D TPM_INTF_CMD_READY_INT
>> -	    | TPM_INTF_LOCALITY_CHANGE_INT | TPM_INTF_DATA_AVAIL_INT
>> -	    | TPM_INTF_STS_VALID_INT | TPM_GLOBAL_INT_ENABLE;
>> +	intmask |=3D priv->supported_irqs | TPM_GLOBAL_INT_ENABLE;
>>
>>  	tpm_tis_write32(priv, TPM_INT_ENABLE(priv->locality), intmask);
>>
>> diff --git a/drivers/char/tpm/tpm_tis_core.h b/drivers/char/tpm/tpm_tis=
_core.h
>> index c8972ea8e13e..3d6b05c6fdba 100644
>> --- a/drivers/char/tpm/tpm_tis_core.h
>> +++ b/drivers/char/tpm/tpm_tis_core.h
>> @@ -97,6 +97,7 @@ struct tpm_tis_data {
>>  	u16 manufacturer_id;
>>  	int locality;
>>  	int irq;
>> +	unsigned int supported_irqs;
>>  	unsigned long irqtest_flags;
>>  	unsigned long flags;
>>  	void __iomem *ilb_base_addr;
>> --
>> 2.36.0
>>
>
> Does the existing code cause issues in a some specific environment?
>
> BR, Jarkko
>

Not that I know of. This patch is not supposed to be a bugfix but an impro=
vement of
the existing code by using the information about supported interrupts whic=
h is collected during
the capability query. After the query we know exactly which irqs are suppo=
rted, so why not use
this knowledge when setting the irq mask?

Regards,
Lino