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

[John "Warthog9" Hawley]

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
>
>
>------------------------------------------------------------------------
>
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