[tpmdd-devel,2/3] tpm_crb: encapsulate crb_wait_for_reg_32
diff mbox

Message ID 1476177787-15003-4-git-send-email-jarkko.sakkinen@linux.intel.com
State New
Headers show

Commit Message

Jarkko Sakkinen Oct. 11, 2016, 9:23 a.m. UTC
Encapsulated crb_wait_for_reg32() so that state changes in other CRB
registers than TPM_CRB_CTRL_REQ_x can be waited.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
---
 drivers/char/tpm/tpm_crb.c | 40 +++++++++++++++++++++++-----------------
 1 file changed, 23 insertions(+), 17 deletions(-)

Comments

Winkler, Tomas Oct. 11, 2016, 10:21 a.m. UTC | #1
> Encapsulated crb_wait_for_reg32() so that state changes in other CRB registers
> than TPM_CRB_CTRL_REQ_x can be waited.
> 
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> ---
>  drivers/char/tpm/tpm_crb.c | 40 +++++++++++++++++++++++-----------------
>  1 file changed, 23 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c index
> c34318b..45f53c2 100644
> --- a/drivers/char/tpm/tpm_crb.c
> +++ b/drivers/char/tpm/tpm_crb.c
> @@ -121,6 +121,25 @@ static int __maybe_unused crb_go_idle(struct device
> *dev, struct crb_priv *priv)
>  	return 0;
>  }
> 
> +static bool crb_wait_for_reg_32(u32 __iomem *reg, u32 mask, u32 value,
> +				unsigned long timeout)
This is a boiler plate register polling function  I would call it _poll_ rather the _wait_

> +{
> +	ktime_t start;
> +	ktime_t stop;
> +
> +	start = ktime_get();
> +	stop = ktime_add(start, ms_to_ktime(timeout));
> +
> +	do {
> +		if ((ioread32(reg) & mask) == value)
I prefer the register value is synced to  variable, this inlining is harder to add adhoc debug prints. 
Also you removed the debug print out that I know when this settled which is important for catching bugs. 
> +			return true;
> +
> +		usleep_range(50, 100);
How do you know this is correct sleep time, I've tuned that for power gating I'm not sure you this fits also for locality. 
> +	} while (ktime_before(ktime_get(), stop));
> +
> +	return false;
> +}
> +

>  /**
>   * crb_cmd_ready - request tpm crb device to enter ready state
>   *
> @@ -138,27 +157,14 @@ static int __maybe_unused crb_go_idle(struct device
> *dev, struct crb_priv *priv)  static int __maybe_unused crb_cmd_ready(struct
> device *dev,
>  					struct crb_priv *priv)
>  {
> -	ktime_t stop, start;
> -	u32 req;
> -
>  	if (priv->flags & CRB_FL_ACPI_START)
>  		return 0;
> 
>  	iowrite32(CRB_CTRL_REQ_CMD_READY, &priv->regs_t->ctrl_req);
> -
> -	start = ktime_get();
> -	stop = ktime_add(start, ms_to_ktime(TPM2_TIMEOUT_C));
> -	do {
> -		req = ioread32(&priv->regs_t->ctrl_req);
> -		if (!(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));
> -
> -	if (ioread32(&priv->regs_t->ctrl_req) & CRB_CTRL_REQ_CMD_READY) {
> +	if (!crb_wait_for_reg_32(&priv->regs_t->ctrl_req,
> +				 CRB_CTRL_REQ_CMD_READY /* mask */,
> +				 0, /* value */
> +				 TPM2_TIMEOUT_C)) {
>  		dev_warn(dev, "cmdReady timed out\n");
>  		return -ETIME;
>  	}
> --
> 2.7.4
> 
> 
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Jarkko Sakkinen Oct. 11, 2016, 11:29 a.m. UTC | #2
On Tue, Oct 11, 2016 at 10:21:03AM +0000, Winkler, Tomas wrote:
> > Encapsulated crb_wait_for_reg32() so that state changes in other CRB registers
> > than TPM_CRB_CTRL_REQ_x can be waited.
> > 
> > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> > ---
> >  drivers/char/tpm/tpm_crb.c | 40 +++++++++++++++++++++++-----------------
> >  1 file changed, 23 insertions(+), 17 deletions(-)
> > 
> > diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c index
> > c34318b..45f53c2 100644
> > --- a/drivers/char/tpm/tpm_crb.c
> > +++ b/drivers/char/tpm/tpm_crb.c
> > @@ -121,6 +121,25 @@ static int __maybe_unused crb_go_idle(struct device
> > *dev, struct crb_priv *priv)
> >  	return 0;
> >  }
> > 
> > +static bool crb_wait_for_reg_32(u32 __iomem *reg, u32 mask, u32 value,
> > +				unsigned long timeout)
> This is a boiler plate register polling function  I would call it _poll_ rather the _wait_
> 
> > +{
> > +	ktime_t start;
> > +	ktime_t stop;
> > +
> > +	start = ktime_get();
> > +	stop = ktime_add(start, ms_to_ktime(timeout));
> > +
> > +	do {
> > +		if ((ioread32(reg) & mask) == value)
> I prefer the register value is synced to  variable, this inlining is
> harder to add adhoc debug prints.  Also you removed the debug print
> out that I know when this settled which is important for catching
> bugs. 

I can add it but can you just briefly explain why the warning
is not enough?

> > +			return true;
> > +
> > +		usleep_range(50, 100);
> How do you know this is correct sleep time, I've tuned that for power
> gating I'm not sure you this fits also for locality. 

Does it matter as long as it is less than for the timeout?

/Jarkko

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Patch
diff mbox

diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c
index c34318b..45f53c2 100644
--- a/drivers/char/tpm/tpm_crb.c
+++ b/drivers/char/tpm/tpm_crb.c
@@ -121,6 +121,25 @@  static int __maybe_unused crb_go_idle(struct device *dev, struct crb_priv *priv)
 	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
  *
@@ -138,27 +157,14 @@  static int __maybe_unused crb_go_idle(struct device *dev, struct crb_priv *priv)
 static int __maybe_unused crb_cmd_ready(struct device *dev,
 					struct crb_priv *priv)
 {
-	ktime_t stop, start;
-	u32 req;
-
 	if (priv->flags & CRB_FL_ACPI_START)
 		return 0;
 
 	iowrite32(CRB_CTRL_REQ_CMD_READY, &priv->regs_t->ctrl_req);
-
-	start = ktime_get();
-	stop = ktime_add(start, ms_to_ktime(TPM2_TIMEOUT_C));
-	do {
-		req = ioread32(&priv->regs_t->ctrl_req);
-		if (!(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));
-
-	if (ioread32(&priv->regs_t->ctrl_req) & CRB_CTRL_REQ_CMD_READY) {
+	if (!crb_wait_for_reg_32(&priv->regs_t->ctrl_req,
+				 CRB_CTRL_REQ_CMD_READY /* mask */,
+				 0, /* value */
+				 TPM2_TIMEOUT_C)) {
 		dev_warn(dev, "cmdReady timed out\n");
 		return -ETIME;
 	}