[SeaBIOS] [PATCH v1 2/3] tpm: Wait for interface startup when probing

[Kevin O'Connor]

On Tue, Feb 27, 2018 at 02:17:10PM -0500, Stephen Douthit wrote:
> This is based on wait_startup() from the Linux tpm_tis driver.
> 
> Signed-off-by: Stephen Douthit <stephend at silicom-usa.com>
> Tested-by: Stephen Douthit <stephend at silicom-usa.com>
> ---
>  src/hw/tpm_drivers.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/src/hw/tpm_drivers.c b/src/hw/tpm_drivers.c
> index 13ad821..da8bb63 100644
> --- a/src/hw/tpm_drivers.c
> +++ b/src/hw/tpm_drivers.c
> @@ -86,6 +86,11 @@ static u32 wait_reg8(u8* reg, u32 time, u8 mask, u8 expect)
>      return rc;
>  }
>  
> +static u32 tis_wait_access(u8 locty, u32 time, u8 mask, u8 expect)
> +{
> +    return wait_reg8(TIS_REG(locty, TIS_REG_ACCESS), time, mask, expect);
> +}
> +
>  static u32 tis_wait_sts(u8 locty, u32 time, u8 mask, u8 expect)
>  {
>      return wait_reg8(TIS_REG(locty, TIS_REG_STS), time, mask, expect);
> @@ -102,7 +107,13 @@ static u32 tis_probe(void)
>      if (!CONFIG_TCGBIOS)
>          return 0;
>  
> -    u32 rc = 0;
> +    /* Wait for the interface to report it's ready */
> +    u32 rc = tis_wait_access(0, TIS_DEFAULT_TIMEOUT_A,
> +                             TIS_ACCESS_TPM_REG_VALID_STS,
> +                             TIS_ACCESS_TPM_REG_VALID_STS);
> +    if (rc)
> +        return 0;
> +

Thanks.  I was about to commit this when I noticed the above.  In the
case where tis_wait_access() fails due to a timeout, shouldn't
tis_probe() return an error indicator instead of success?

-Kevin