RE: [PATCH v3 1/4] tpm/tpm_crb: implement tpm crb idle state

[Winkler, Tomas]

> On Thu, Sep 15, 2016 at 08:23:03AM +0000, Winkler, Tomas wrote:
> > > > > Subject: Re: [PATCH v3 1/4] tpm/tpm_crb: implement tpm crb idle
> > > > > state
> > > > >
> > > > > On Mon, Sep 12, 2016 at 04:04:18PM +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.
> > > > > >
> > > > > > Based on Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
> > > > > > oringal
> > > > > > patch:
> > > > > > 'tpm_crb: implement power tpm crb power management'
> > > > > >
> > > > > >
> > > > > > Signed-off-by: Tomas Winkler <tomas.winkler@xxxxxxxxx>
> > > > > > ---
> > > > > > V2: do not export the functions via tpm ops
> > > > > > V3: fix lower case corruption; adjust function documentation
> > > > > >
> > > > > >  drivers/char/tpm/tpm_crb.c | 69
> > > > > > ++++++++++++++++++++++++++++++++++++++++++++++
> > > > > >  1 file changed, 69 insertions(+)
> > > > > >
> > > > > > diff --git a/drivers/char/tpm/tpm_crb.c
> > > > > > b/drivers/char/tpm/tpm_crb.c index 6e9d1bca712f..b6923a8b3ff7
> > > > > > 100644
> > > > > > --- a/drivers/char/tpm/tpm_crb.c
> > > > > > +++ b/drivers/char/tpm/tpm_crb.c
> > > > > > @@ -83,6 +83,75 @@ struct crb_priv {
> > > > > >  	u32 cmd_size;
> > > > > >  };
> > > > > >
> > > > > > +/**
> > > > > > + * crb_go_idle - request tpm crb device to go the idle state
> > > > > > + *
> > > > > > + * @dev:  crb device
> > > > > > + * @priv: crb private data
> > > > > > + *
> > > > > > + * 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.
> > > > > > + *
> > > > > > + * The function does nothing for devices with ACPI-start method.
> > > > > > + *
> > > > > > + * Return: 0 always
> > > > > > + */
> > > > > > +static int __maybe_unused 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;
> > > > > > +}
> > > > > > +
> > > > > > +/**
> > > > > > + * crb_cmd_ready - request tpm crb device to enter ready
> > > > > > +state
> > > > > > + *
> > > > > > + * @dev:  crb device
> > > > > > + * @priv: crb private data
> > > > > > + *
> > > > > > + * 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
> > > > > > + *
> > > > > > + * Return: 0 on success -ETIME on timeout;  */ static int
> > > > > > +__maybe_unused 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(50, 100);
> > > > > > +	} while (ktime_before(ktime_get(), stop));
> > > > >
> > > > > Since this is HW specific this is right thing to do and not
> > > > > abuse wait_for_tpm_stat. However, this should be documented to
> > > > > the commit message.
> > > > I will respin just this patch and not the whole series, as the fix
> > > > is only in the
> > > commit message.
> > > > Tomas
> > >
> > > Works for me. I can update pm_runtime_sync(). Then I'm ready to
> > > apply these.
> >
> > What do you mean by pm_runtime_sync()?
> 
> Typo. I already commente v2 of the series that pm_runtime_put should be
> used instead of pm_runtime_put_sync.

This is not necessary, it's okay to suspend in asynchronous mode.
Tomas