Re: [PATCH 1/3] tpm/tpm_crb: implement tpm crb idle state

[Jarkko Sakkinen <jarkko.sakkinen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>]

On Wed, Sep 07, 2016 at 02:32:31PM +0300, Tomas Winkler wrote:
> The register TPM_CRB_CTRL_REQ_x contains bits goIdle and cmdReady for
> SW to indicate that the device can enter or should exit the idle state.
> 
> The legacy ACPI-start (SMI + DMA) based devices do not support these
> bits and the idle state management is not exposed to the host SW.
> Thus, this functionality only is enabled only for a CRB start (MMIO)
> based devices.
> 
> We introduce two new callbacks for command ready and go idle for TPM CRB
> device which are called across TPM transactions.
> 
> Based on Jarkko Sakkinen <jarkko.sakkinen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org> oringal patch
> 'tpm_crb: implement power tpm crb power management'
> 
> Signed-off-by: Tomas Winkler <tomas.winkler-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
> ---
>  drivers/char/tpm/tpm-interface.c | 21 +++++++++++
>  drivers/char/tpm/tpm_crb.c       | 77 ++++++++++++++++++++++++++++++++++++++++
>  include/linux/tpm.h              |  3 +-
>  3 files changed, 100 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
> index fd863ff30f79..c78dca5ce7a6 100644
> --- a/drivers/char/tpm/tpm-interface.c
> +++ b/drivers/char/tpm/tpm-interface.c
> @@ -327,6 +327,20 @@ unsigned long tpm_calc_ordinal_duration(struct tpm_chip *chip,
>  }
>  EXPORT_SYMBOL_GPL(tpm_calc_ordinal_duration);
>  
> +static inline int tpm_go_idle(struct tpm_chip *chip)
> +{
> +	if (!chip->ops->idle)
> +		return 0;
> +	return chip->ops->idle(chip);
> +}
> +
> +static inline int tpm_cmd_ready(struct tpm_chip *chip)
> +{
> +	if (!chip->ops->ready)
> +		return 0;
> +	return chip->ops->ready(chip);
> +}
> +
>  /*
>   * Internal kernel interface to transmit TPM commands
>   */
> @@ -353,6 +367,10 @@ ssize_t tpm_transmit(struct tpm_chip *chip, const u8 *buf, size_t bufsiz,
>  	if (!(flags & TPM_TRANSMIT_UNLOCKED))
>  		mutex_lock(&chip->tpm_mutex);
>  
> +	rc = tpm_cmd_ready(chip);
> +	if (rc)
> +		goto out;
> +
>  	rc = chip->ops->send(chip, (u8 *) buf, count);
>  	if (rc < 0) {
>  		dev_err(&chip->dev,
> @@ -394,8 +412,11 @@ out_recv:
>  		dev_err(&chip->dev,
>  			"tpm_transmit: tpm_recv: error %zd\n", rc);
>  out:
> +	tpm_go_idle(chip);
> +
>  	if (!(flags & TPM_TRANSMIT_UNLOCKED))
>  		mutex_unlock(&chip->tpm_mutex);
> +
>  	return rc;
>  }
>  
> diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c
> index 82a3ccd52a3a..98a7fdfe9936 100644
> --- a/drivers/char/tpm/tpm_crb.c
> +++ b/drivers/char/tpm/tpm_crb.c
> @@ -83,6 +83,81 @@ struct crb_priv {
>  	u8 __iomem *rsp;
>  };
>  
> +/**
> + * __crb_go_idle - write CRB_CTRL_REQ_GO_IDLE to TPM_CRB_CTRL_REQ
> + *    The device should respond within TIMEOUT_C by clearing the bit.
> + *    Anyhow, we do not wait here as a consequent CMD_READY request
> + *    will be handled correctly even if idle was not completed.
> + *
> + * @dev: tpm device
> + * @priv: crb private context
> + *
> + * Return:  0 always
> + */
> +static int __crb_go_idle(struct device *dev, struct crb_priv *priv)
> +{
> +	if (priv->flags & CRB_FL_ACPI_START)
> +		return 0;
> +	iowrite32(CRB_CTRL_REQ_GO_IDLE, &priv->cca->req);
> +	/* we don't really care when this settles */
> +
> +	return 0;
> +}
> +
> +static int crb_go_idle(struct tpm_chip *chip)
> +{
> +	struct crb_priv *priv = dev_get_drvdata(&chip->dev);
> +
> +	return __crb_go_idle(&chip->dev, priv);
> +}
> +
> +/**
> + * __crb_cmd_ready - write CRB_CTRL_REQ_CMD_READY to TPM_CRB_CTRL_REQ
> + *      and poll till the device acknowledge it by clearing the bit.
> + *      The device should respond within TIMEOUT_C.
> + *
> + *      The function does nothing for devices with ACPI-start method
> + *
> + * @dev: tpm device
> + * @priv: crb private context
> + *
> + * Return:  0 on success -ETIME on timeout;
> + */
> +static int __crb_cmd_ready(struct device *dev, struct crb_priv *priv)
> +{
> +	ktime_t stop, start;
> +
> +	if (priv->flags & CRB_FL_ACPI_START)
> +		return 0;
> +
> +	iowrite32(CRB_CTRL_REQ_CMD_READY, &priv->cca->req);
> +
> +	start = ktime_get();
> +	stop = ktime_add(start, ms_to_ktime(TPM2_TIMEOUT_C));
> +	do {
> +		if (!(ioread32(&priv->cca->req) & CRB_CTRL_REQ_CMD_READY)) {
> +			dev_dbg(dev, "cmdReady in %lld usecs\n",
> +				ktime_to_us(ktime_sub(ktime_get(), start)));
> +			return 0;
> +		}
> +		usleep_range(500, 1000);
> +	} while (ktime_before(ktime_get(), stop));

What's the problem of using wait_for_tpm_stat like:

http://git.infradead.org/users/jjs/linux-tpmdd.git/commitdiff/7a1172b5b3cb38083ae931309db216db3c528efe

/Jarkko

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