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

[Stefan Berger]

On 02/26/2018 03:37 PM, 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 8d6fc33..789d70a 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;
> +
>       u32 didvid = readl(TIS_REG(0, TIS_REG_DID_VID));
>
>       if ((didvid != 0) && (didvid != 0xffffffff))


On QEMU that VALID flag is always set.

Reviewed-by: Stefan Berger <stefanb at linux.vnet.ibm.com>