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Date:   Sun, 26 Jun 2022 09:40:43 +0300
From:   Jarkko Sakkinen <jarkko@kernel.org>
To:     Lino Sanfilippo <LinoSanfilippo@gmx.de>
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, l.sanfilippo@kunbus.com,
        lukas@wunner.de, p.rosenberger@kunbus.com
Subject: Re: [PATCH v6 5/9] tpm, tpm_tis: Only handle supported interrupts
Message-ID: <Yrf/azvJlzWfOE9y@kernel.org>
References: <20220621132447.16281-1-LinoSanfilippo@gmx.de>
 <20220621132447.16281-6-LinoSanfilippo@gmx.de>
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On Tue, Jun 21, 2022 at 03:24:43PM +0200, Lino Sanfilippo wrote:
> From: Lino Sanfilippo <l.sanfilippo@kunbus.com>
> 
> According to the TPM Interface Specification (TIS) support for "stsValid"
> and "commandReady" interrupts is only optional.
> This has to be taken into account when handling the interrupts in functions
> like wait_for_tpm_stat(). To determine the supported interrupts use the
> capability query.
> 
> Also adjust wait_for_tpm_stat() to only wait for interrupt reported status
> changes. After that process all the remaining status changes by polling
> the status register.
> 
> Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
> ---
>  drivers/char/tpm/tpm_tis_core.c | 119 +++++++++++++++++++-------------
>  drivers/char/tpm/tpm_tis_core.h |   1 +
>  2 files changed, 72 insertions(+), 48 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
> index 09d8f04cbc81..cb469591373a 100644
> --- a/drivers/char/tpm/tpm_tis_core.c
> +++ b/drivers/char/tpm/tpm_tis_core.c
> @@ -53,41 +53,63 @@ static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask,
>  	long rc;
>  	u8 status;
>  	bool canceled = false;
> +	u8 sts_mask = 0;
> +	int ret = 0;
>  
>  	/* check current status */
>  	status = chip->ops->status(chip);
>  	if ((status & mask) == mask)
>  		return 0;
>  
> -	stop = jiffies + timeout;
> +	/* check what status changes can be handled by irqs */
> +	if (priv->int_mask & TPM_INTF_STS_VALID_INT)
> +		sts_mask |= TPM_STS_VALID;
>  
> -	if (chip->flags & TPM_CHIP_FLAG_IRQ) {
> +	if (priv->int_mask & TPM_INTF_DATA_AVAIL_INT)
> +		sts_mask |= TPM_STS_DATA_AVAIL;
> +
> +	if (priv->int_mask & TPM_INTF_CMD_READY_INT)
> +		sts_mask |= TPM_STS_COMMAND_READY;
> +
> +	sts_mask &= mask;

I would instead mask out bits and write a helper function
taking care of this:

static u8 tpm_tis_filter_sts_mask(u8 int_mask, u8 sts_mask)
{
        struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);

        if (!(int_mask & TPM_INTF_STS_VALID_INT))
                sts_mask &= ~TPM_STS_VALID;

        if (!(int_mask & TPM_INTF_DATA_AVAIL_INT))
                sts_mask &= ~TPM_STS_DATA_AVAIL;

        if (!(int_mask & TPM_INTF_CMD_READY_INT))
		sts_mask &= ~TPM_STS_COMMAND_READY;

        return sts_mask;
}

Less operations and imho somewhat cleaner structure.

Add suggested-by if you want.

BR, Jarkko