Re: [PATCH] tpm_tis: TPM_STS_DATA_EXPECT workaround

[David Smith]

Hi, can this be merged, please? Using the module parameter is not
optimal but it's better than the complete lack of support today.

On Fri, Sep 25, 2009 at 3:43 AM, Rajiv Andrade
<srajiv@xxxxxxxxxxxxxxxxxx> wrote:
> This was already tested and, given no more comments on it, finally
> reviewed. Can it already be merged?
>
> Thanks,
> Rajiv
>
> On Sat, 2009-09-12 at 08:34 +0900, Seiji Munetoh wrote:
>> On Fri, Sep 11, 2009 at 5:09 AM, Rajiv Andrade
>> <srajiv@xxxxxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxxxxx>
>>
>> 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@xxxxxxxxx>
>>
>> > ---
>> > 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 +
>> >
>> >
>> >
>> --
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>
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