[MinnowBoard] Using a TPM on the MinnowBoard connected with I2C

[Sebastien Duc]

Quick update.
I managed to figure out that bus 7 was not the right one and discovered
that it was bus 1 (/dev/i2c-1).
I used it in my kernel module with slave address 0x29 and I can now to talk
to the TPM.
Thanks a lot John for the help.

Sebastien

On 17 November 2015 at 15:40, Sebastien Duc <sebastien.duc at yoti.com> wrote:

> Thanks John for the reply.
> I created a kernel module very similar to ones on github as you said. But
> I cannot load it successfully.
> From what you said my understanding is that I need to find the i2c bus and
> the slave address of the TPM chip.
> I found on Google that the bus should be i2c-7. When using i2c-detect on 7
> I get  i2c slaves at multiple addresses:
> 0x37, 0x3a, 0x49, 0x50 and 0x59.
> How do I know which one I should use? I found on this page
> https://github.com/theopolis/tpm-i2c-atmel that the address should be
> 0x29 but that address does not appear in i2c-detect. Any clue why?
>
> Thanks,
> Sebastien
>
> On 16 November 2015 at 18:00, John "Warthog9" Hawley <
> warthog19 at eaglescrag.net> wrote:
>
>> Apologies for briefness in this, I'm traveling, but the reason this isn't
>> working is the kernel needs to be informed where the Atmel chip is. The
>> quickest way is to write a small kernel module typically referred to as a
>> board file. You can find an example of several of these in the
>> minnow-max-extras repo on github. Basically you need to load the bus, and
>> address of where the Atmel chip is, since it can't be auto discovered like
>> pci, usb, etc.
>>
>> - John "Warthog9" Hawley
>>
>>
>> On November 16, 2015 10:11:49 AM CST, Sebastien Duc <
>> sebastien.duc at yoti.com> wrote:
>>>
>>> Hi all,
>>>
>>> Please bare with me if something I am saying is wrong, I don't have much
>>> experience with TPMs or I2C.
>>>
>>> I recently acquired a minnowboard max to attempt some experimentation
>>> with TPMs.
>>> I have also bought a separate TPM from Atmel (it's the TPM i2c
>>> development Kit AT97SC3205T).
>>>
>>> So far I have connected the TPM board to the Minnowboard through i2c. I
>>> made sure to connect pin 2 (the ground) and 4 (+3V3) of the Minnowboard to
>>> the corresponding GND and VCC of my TPM board. I also connected pin 13
>>> (SCL) and 15 (SDA) to the corresponding SCL and SDA of the TPM board.
>>>
>>> I have installed Debian on the board and made sure to build a kernel
>>> that has tpm_i2c_atmel as a module. The version of my kernel is 4.3.0.
>>>
>>> Now I am trying to load the kernel module as so:
>>> # insmod tpm_i2c_atmel.ko
>>>
>>> The insmod is being executed without any errors and I cannot see
>>> anything in dmesg.
>>> However when looking at my devices, I don't see any tpm0 in /dev.
>>>
>>> I can also see tpm_i2c atmel.ko in the list of loaded modules when
>>> looking at
>>> # lsmod
>>>
>>> Therefore when I am trying to start tcsd, it fails:
>>> # tcsd -f
>>> # TCSD TDDL ERROR: Could not find a device to open!
>>>
>>> I also made sure in the BIOS  to enable Discrete TPM.
>>>
>>> So my guess is that either my TPM is not properly connect but I don't
>>> really know how to test this. Or I am missing some software configuration
>>> somewhere.
>>>
>>> I was hoping that someone could help me with this. How can I know if I
>>> did the connectivity properly? What configuration do I need to do before
>>> being able to talk to the TPM, especially to use the i2c pins on the
>>> Minnowboard?
>>>
>>> Let me know if you need more information.
>>>
>>> Thanks,
>>> Sebastien
>>>
>> ------------------------------
>>
>> elinux-MinnowBoard mailing list
>> elinux-MinnowBoard at lists.elinux.org
>> http://lists.elinux.org/mailman/listinfo/elinux-minnowboard
>>
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.elinux.org/pipermail/elinux-minnowboard/attachments/20151117/bca1f4c8/attachment.html>