Re: [tboot-devel] [tpmdd-devel] TPM driver problem on GM45

[Seiji M. <sei...@gm...>]

On Tue, Dec 2, 2008 at 7:29 AM, Cihula, Joseph <jos...@in...> wrote:
>> From: Seiji Munetoh [mailto:sei...@gm...]
>> Sent: Monday, December 01, 2008 2:24 PM
>>
>> On Mon, Dec 1, 2008 at 4:53 PM, Marcin Obara
>> <mar...@us...> wrote:
>> > 2008/12/1 Seiji Munetoh <sei...@gm...>:
>> >> 2008/11/28 Marcin Obara <mar...@us...>:
>> >>> Linux is not supported by iTPM on these mobile platforms.
>> >>> iTPM on these platforms will work only with Windows OS-es.
>> >>
>> >> So, do we need special driver to access the iTPM?
>> >
>> > It is not driver issue. It is platform design.
>> > iTPM on these (mobile) platforms was designed to work only with
>> > Windows OS-es. It is not possible to use any TPM Linux driver on these
>> > platforms.
>> > iTPM on other (desktop) platforms should work with standard Linux -
>> > tpm_tis driver.
>>
>> So we can't use tboot & xen also on these platforms:-(
>>
>> thanks,
>> Seiji
>
> (cross-posting to tboot-devel since this question concerns that project)
>
> tboot will work fine on these systems, since it accesses
> the TPM directly through its MMIO interface.  You will just have
> to use a non-Linux environment and tools to provision the
> TXT LCP and tboot policy indices.

I think tpm_tis driver also uses MMIO.
I have take a look the detail. and It seems there are two problems.
- iTPM on GM45 does not supports PNP
- It return wrong TIS status???

Here is Quick-and-dirty fix:
1) modify status check of tpm_tis_send() function.
e.g.
-		if ((status & TPM_STS_DATA_EXPECT) == 0) {
+		if ((status & TPM_STS_VALID) == 0) {

and rebuild the tpm_tis driver

2) Force device probe rather than using ACPI entry

/sbin/modprobe tpm_tis force=1

if it returns error, try again.
then you can access the iTPM on GM45 from Linux.

regards,
Seiji