linux-kernel - Re: [PATCH v2 2/3] tpm_crb: encapsulate crb_wait_for_reg

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Message-ID: <20161203184137.p4mk3gdldcflty5x@intel.com>
Date:   Sat, 3 Dec 2016 20:41:37 +0200
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Peter Huewe <peterhuewe@....de>
Cc:     Marcel Selhorst <tpmdd@...horst.net>,
        Jason Gunthorpe <jgunthorpe@...idianresearch.com>,
        "moderated list:TPM DEVICE DRIVER" 
        <tpmdd-devel@...ts.sourceforge.net>,
        open list <linux-kernel@...r.kernel.org>,
        linux-security-module@...r.kernel.org
Subject: Re: [PATCH v2 2/3] tpm_crb: encapsulate crb_wait_for_reg_32

CC linux-security-module

On Sat, Dec 03, 2016 at 07:52:12PM +0200, Jarkko Sakkinen 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@...ux.intel.com>
> ---
>  drivers/char/tpm/tpm_crb.c | 37 +++++++++++++++++++++++--------------
>  1 file changed, 23 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c
> index 8d81b66..f986d02 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
>   *
> @@ -138,24 +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))
> -			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;
>  	}
> -- 
> 2.9.3
>