RE: [PATCH 1/3] tpm: cmd_ready command can be issued only after granting locality

[Winkler, Tomas]

> > The correct sequence is to first request locality and only after that
> > perform cmd_ready  handshake, otherwise the hardware will drop the
> > subsequent message as from the device point of view the cmd_ready
> > handshake wasn't performed. Symmetrically locality has to be
> > relinquished only after going idle handshake has completed, this
> > requires that go_idle has to poll for the completion.
> >
> > The issue is only visible on devices that support multiple localities.
> >
> > Signed-off-by: Tomas Winkler <tomas.winkler@xxxxxxxxx>
> 
> Thank you!
> 
> > ---
> >  drivers/char/tpm/tpm-interface.c | 12 ++---
> >  drivers/char/tpm/tpm_crb.c       | 95 ++++++++++++++++++++++++++---------
> -----
> >  2 files changed, 70 insertions(+), 37 deletions(-)
> >
> > diff --git a/drivers/char/tpm/tpm-interface.c
> > b/drivers/char/tpm/tpm-interface.c
> > index 76df4fbcf089..197fda39aab5 100644
> > --- a/drivers/char/tpm/tpm-interface.c
> > +++ b/drivers/char/tpm/tpm-interface.c
> > @@ -422,8 +422,6 @@ ssize_t tpm_transmit(struct tpm_chip *chip, struct
> tpm_space *space,
> >  	if (!(flags & TPM_TRANSMIT_UNLOCKED))
> >  		mutex_lock(&chip->tpm_mutex);
> >
> > -	if (chip->dev.parent)
> > -		pm_runtime_get_sync(chip->dev.parent);
> >
> >  	if (chip->ops->clk_enable != NULL)
> >  		chip->ops->clk_enable(chip, true);
> > @@ -439,6 +437,9 @@ ssize_t tpm_transmit(struct tpm_chip *chip, struct
> tpm_space *space,
> >  		chip->locality = rc;
> >  	}
> >
> > +	if (chip->dev.parent)
> > +		pm_runtime_get_sync(chip->dev.parent);
> > +
> >  	rc = tpm2_prepare_space(chip, space, ordinal, buf);
> >  	if (rc)
> >  		goto out;
> > @@ -499,17 +500,18 @@ ssize_t tpm_transmit(struct tpm_chip *chip,
> struct tpm_space *space,
> >  	rc = tpm2_commit_space(chip, space, ordinal, buf, &len);
> >
> >  out:
> > +	if (chip->dev.parent)
> > +		pm_runtime_put_sync(chip->dev.parent);
> > +
> >  	if (need_locality && chip->ops->relinquish_locality) {
> >  		chip->ops->relinquish_locality(chip, chip->locality);
> >  		chip->locality = -1;
> >  	}
> > +
> >  out_no_locality:
> >  	if (chip->ops->clk_enable != NULL)
> >  		chip->ops->clk_enable(chip, false);
> >
> > -	if (chip->dev.parent)
> > -		pm_runtime_put_sync(chip->dev.parent);
> > -
> >  	if (!(flags & TPM_TRANSMIT_UNLOCKED))
> >  		mutex_unlock(&chip->tpm_mutex);
> >  	return rc ? rc : len;
> > diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c
> > index 7b3c2a8aa9de..d174919c446d 100644
> > --- a/drivers/char/tpm/tpm_crb.c
> > +++ b/drivers/char/tpm/tpm_crb.c
> > @@ -112,6 +112,25 @@ struct tpm2_crb_smc {
> >  	u32 smc_func_id;
> >  };
> >
> > +static bool crb_wait_for_reg_32(u32 __iomem *reg, u32 mask, u32 value,
> > +				unsigned long timeout)
> > +{
> > +	ktime_t start;
> > +	ktime_t stop;
> > +
> > +	start = ktime_get();
> > +	stop = ktime_add(start, ms_to_ktime(timeout));
> > +
> > +	do {
> > +		if ((ioread32(reg) & mask) == value)
> > +			return true;
> > +
> > +		usleep_range(50, 100);
> > +	} while (ktime_before(ktime_get(), stop));
> > +
> > +	return ((ioread32(reg) & mask) == value);
> 
> Not sure about the change of return statement. Is this worth of doing?
The sleep statement is followed directly by loop time comparison. It should take care
for case when the change in the value happens in that time windows on the edge of the timeout.
When I look at the traces I think we should maybe make that sleep  little longer to reduce number of 
register access, but some more tests need to be done on multiple platforms. 


> 
> > +}
> > +
> >  /**
> >   * crb_go_idle - request tpm crb device to go the idle state
> >   *
> > @@ -128,7 +147,7 @@ struct tpm2_crb_smc {
> >   *
> >   * Return: 0 always
> >   */
> > -static int __maybe_unused crb_go_idle(struct device *dev, struct
> > crb_priv *priv)
> > +static int crb_go_idle(struct device *dev, struct crb_priv *priv)
> >  {
> >  	if ((priv->sm == ACPI_TPM2_START_METHOD) ||
> >  	    (priv->sm ==
> ACPI_TPM2_COMMAND_BUFFER_WITH_START_METHOD) || @@
> > -136,30 +155,17 @@ static int __maybe_unused crb_go_idle(struct device
> *dev, struct crb_priv *priv)
> >  		return 0;
> >
> >  	iowrite32(CRB_CTRL_REQ_GO_IDLE, &priv->regs_t->ctrl_req);
> > -	/* we don't really care when this settles */
> >
> > +	if (!crb_wait_for_reg_32(&priv->regs_t->ctrl_req,
> > +				 CRB_CTRL_REQ_GO_IDLE/* mask */,
> > +				 0, /* value */
> > +				 TPM2_TIMEOUT_C)) {
> > +		dev_warn(dev, "goIdle timed out\n");
> > +		return -ETIME;
> > +	}
> >  	return 0;
> >  }
> >
> > -static bool crb_wait_for_reg_32(u32 __iomem *reg, u32 mask, u32 value,
> > -				unsigned long timeout)
> > -{
> > -	ktime_t start;
> > -	ktime_t stop;
> > -
> > -	start = ktime_get();
> > -	stop = ktime_add(start, ms_to_ktime(timeout));
> > -
> > -	do {
> > -		if ((ioread32(reg) & mask) == value)
> > -			return true;
> > -
> > -		usleep_range(50, 100);
> > -	} while (ktime_before(ktime_get(), stop));
> > -
> > -	return false;
> > -}
> > -
> >  /**
> >   * crb_cmd_ready - request tpm crb device to enter ready state
> >   *
> > @@ -175,8 +181,7 @@ static bool crb_wait_for_reg_32(u32 __iomem *reg,
> u32 mask, u32 value,
> >   *
> >   * Return: 0 on success -ETIME on timeout;
> >   */
> > -static int __maybe_unused crb_cmd_ready(struct device *dev,
> > -					struct crb_priv *priv)
> > +static int crb_cmd_ready(struct device *dev, struct crb_priv *priv)
> >  {
> >  	if ((priv->sm == ACPI_TPM2_START_METHOD) ||
> >  	    (priv->sm ==
> ACPI_TPM2_COMMAND_BUFFER_WITH_START_METHOD) || @@
> > -195,11 +200,11 @@ static int __maybe_unused crb_cmd_ready(struct
> device *dev,
> >  	return 0;
> >  }
> >
> > -static int crb_request_locality(struct tpm_chip *chip, int loc)
> > +static int __crb_request_locality(struct device *dev,
> > +				  struct crb_priv *priv, int loc)
> >  {
> > -	struct crb_priv *priv = dev_get_drvdata(&chip->dev);
> >  	u32 value = CRB_LOC_STATE_LOC_ASSIGNED |
> > -		CRB_LOC_STATE_TPM_REG_VALID_STS;
> > +		    CRB_LOC_STATE_TPM_REG_VALID_STS;
> >
> >  	if (!priv->regs_h)
> >  		return 0;
> > @@ -207,23 +212,36 @@ static int crb_request_locality(struct tpm_chip
> *chip, int loc)
> >  	iowrite32(CRB_LOC_CTRL_REQUEST_ACCESS, &priv->regs_h-
> >loc_ctrl);
> >  	if (!crb_wait_for_reg_32(&priv->regs_h->loc_state, value, value,
> >  				 TPM2_TIMEOUT_C)) {
> > -		dev_warn(&chip->dev, "TPM_LOC_STATE_x.requestAccess
> timed out\n");
> > +		dev_warn(dev, "TPM_LOC_STATE_x.requestAccess timed
> out\n");
> >  		return -ETIME;
> >  	}
> >
> >  	return 0;
> >  }
> >
> > -static void crb_relinquish_locality(struct tpm_chip *chip, int loc)
> > +static int crb_request_locality(struct tpm_chip *chip, int loc)
> >  {
> >  	struct crb_priv *priv = dev_get_drvdata(&chip->dev);
> >
> > +	return __crb_request_locality(&chip->dev, priv, loc); }
> > +
> > +static void __crb_relinquish_locality(struct device *dev,
> > +				      struct crb_priv *priv, int loc) {
> >  	if (!priv->regs_h)
> >  		return;
> >
> >  	iowrite32(CRB_LOC_CTRL_RELINQUISH, &priv->regs_h->loc_ctrl);  }
> >
> > +static void crb_relinquish_locality(struct tpm_chip *chip, int loc) {
> > +	struct crb_priv *priv = dev_get_drvdata(&chip->dev);
> > +
> > +	__crb_relinquish_locality(&chip->dev, priv, loc); }
> > +
> >  static u8 crb_status(struct tpm_chip *chip)  {
> >  	struct crb_priv *priv = dev_get_drvdata(&chip->dev); @@ -475,6
> > +493,10 @@ static int crb_map_io(struct acpi_device *device, struct
> crb_priv *priv,
> >  			dev_warn(dev, FW_BUG "Bad ACPI memory layout");
> >  	}
> >
> > +	ret = __crb_request_locality(dev, priv, 0);
> > +	if (ret)
> > +		return ret;
> > +
> >  	priv->regs_t = crb_map_res(dev, priv, &io_res, buf->control_address,
> >  				   sizeof(struct crb_regs_tail));
> >  	if (IS_ERR(priv->regs_t))
> > @@ -531,6 +553,8 @@ static int crb_map_io(struct acpi_device *device,
> > struct crb_priv *priv,
> >
> >  	crb_go_idle(dev, priv);
> >
> > +	__crb_relinquish_locality(dev, priv, 0);
> > +
> >  	return ret;
> >  }
> >
> > @@ -588,10 +612,14 @@ static int crb_acpi_add(struct acpi_device
> *device)
> >  	chip->acpi_dev_handle = device->handle;
> >  	chip->flags = TPM_CHIP_FLAG_TPM2;
> >
> > -	rc  = crb_cmd_ready(dev, priv);
> > +	rc = __crb_request_locality(dev, priv, 0);
> >  	if (rc)
> >  		return rc;
> >
> > +	rc  = crb_cmd_ready(dev, priv);
> > +	if (rc)
> > +		goto out;
> > +
> >  	pm_runtime_get_noresume(dev);
> >  	pm_runtime_set_active(dev);
> >  	pm_runtime_enable(dev);
> > @@ -601,12 +629,15 @@ static int crb_acpi_add(struct acpi_device
> *device)
> >  		crb_go_idle(dev, priv);
> >  		pm_runtime_put_noidle(dev);
> >  		pm_runtime_disable(dev);
> > -		return rc;
> > +		goto out;
> >  	}
> >
> > -	pm_runtime_put(dev);
> > +	pm_runtime_put_sync(dev);
> 
> Change to put_sync is needed so that the idle handshake gets completed?

Right.
 
> >
> > -	return 0;
> > +out:
> > +	__crb_relinquish_locality(dev, priv, 0);
> > +
> > +	return rc;
> >  }
> >
> >  static int crb_acpi_remove(struct acpi_device *device)
> > --
> > 2.14.3
> >
> 
> /Jarkko