Re: [PATCH] tpm_tis: TPM_STS_DATA_EXPECT workaround

[Seiji Munetoh <seiji.munetoh@gmail.com>]

On Fri, Sep 11, 2009 at 5:09 AM, Rajiv Andrade
<srajiv@linux.vnet.ibm.com> wrote:
> Some newer Lenovo models are shipped with a TPM that doesn't seem to set the TPM_STS_DATA_EXPECT status bit
> when sending it a burst of data, so the code understands it as a failure and doesn't proceed sending the chip
> the intended data. In this patch we bypass this bit check in case the itpm module parameter was set.
>
> This patch is based on Andy Isaacson's one:
>
> http://marc.info/?l=linux-kernel&m=124650185023495&w=2
>
> It was heavily discussed how should we deal with identifying the chip in kernel space, but the required
> patch to do so was NACK'd:
>
> http://marc.info/?l=linux-kernel&m=124650186423711&w=2
>
> This way we let the user choose using this workaround or not based on his
> observations on this code behavior when trying to use the TPM.
>
> Fixed a checkpatch issue present on the previous patch, thanks to Daniel Walker.
>
> Signed-off-by: Rajiv Andrade <srajiv@linux.vnet.ibm.com>

As far as I know, only the intel tpm has this PNP issue, so I'm fine with it.

Tested-by: Seiji Munetoh <seiji.munetoh@gmail.com>

> ---
> diff --git a/drivers/char/tpm/tpm_tis.c b/drivers/char/tpm/tpm_tis.c
> index aec1931..c9990db 100644
> --- a/drivers/char/tpm/tpm_tis.c
> +++ b/drivers/char/tpm/tpm_tis.c
> @@ -257,6 +257,10 @@ out:
>        return size;
>  }
>
> +static int itpm;
> +module_param(itpm, bool, 0444);
> +MODULE_PARM_DESC(itpm, "Force iTPM workarounds (found on some Lenovo laptops)");
> +
>  /*
>  * If interrupts are used (signaled by an irq set in the vendor structure)
>  * tpm.c can skip polling for the data to be available as the interrupt is
> @@ -293,7 +297,7 @@ static int tpm_tis_send(struct tpm_chip *chip, u8 *buf, size_t len)
>                wait_for_stat(chip, TPM_STS_VALID, chip->vendor.timeout_c,
>                              &chip->vendor.int_queue);
>                status = tpm_tis_status(chip);
> -               if ((status & TPM_STS_DATA_EXPECT) == 0) {
> +               if (!itpm && (status & TPM_STS_DATA_EXPECT) == 0) {
>                        rc = -EIO;
>                        goto out_err;
>                }
> @@ -467,6 +471,10 @@ static int tpm_tis_init(struct device *dev, resource_size_t start,
>                 "1.2 TPM (device-id 0x%X, rev-id %d)\n",
>                 vendor >> 16, ioread8(chip->vendor.iobase + TPM_RID(0)));
>
> +       if (itpm)
> +               dev_info(dev, "Intel iTPM workaround enabled\n");
> +
> +
>        /* Figure out the capabilities */
>        intfcaps =
>            ioread32(chip->vendor.iobase +
>
>
>