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

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

On Thu, Sep 08, 2016 at 02:11:15PM +0300, Jarkko Sakkinen wrote:
> 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

I'm proponent for my version since it's less intrusive change and adds
less ad-hoc code to the CRB driver.

Would you mind if I would construct v3 with two patches from this patch
set and my version with some tweaks from your code that are needed for
the workaround?

/Jarkko

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