I'm looking to do some quick and dirty proof of concept for a project, and need a TPM module that will work with a Raspberry pi with minimal fuss. I2C, SPI, or parallel doesn't matter - in fact performance is mostly irrelevant; the POC only needs to the TPM for the PKCS private RSA key, using it to identify itself (indirectly, by proof of knowledge and by generating session secrets and HMAC signing keys). The public key will of course be totally public. The private key won't be used for anything else at all (though obviously it needs to implement the RSA bignum expmod so this will be implicitly offloaded). I don't need secure boot or anything like that; this is intended to be customer premises equipment and if they want to fiddle with it they're perfectly welcome to and the only requirement is they can't change or directly access the private key. (This is for trust to prevent impersonation, MITM, key leaks, etc.) I *could* do PKCS in software using only openssh, but the hardware private key part is a major selling point...
Some GPIO and a couple of relays would be handy as well.
I'd rather not spend time rolling my own here just for a super simple POC demonstration...