linux-kernel - Re: [PATCH v2 2/2] tpm: tis: add support for MMIO TPM on SynQuacer

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Message-ID: <CAKv+Gu-9KvzLEcNQnRfsOkU=5oc1otY_NS15fR5Oi4Z4UVvurw@mail.gmail.com>
Date:   Thu, 23 Jan 2020 13:29:55 +0100
From:   Ard Biesheuvel <ard.biesheuvel@...aro.org>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Cc:     Ard Biesheuvel <ardb@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Masahisa Kojima <masahisa.kojima@...aro.org>,
        Devicetree List <devicetree@...r.kernel.org>,
        linux-integrity <linux-integrity@...r.kernel.org>,
        Peter Hüwe <peterhuewe@....de>,
        Jason Gunthorpe <jgg@...pe.ca>
Subject: Re: [PATCH v2 2/2] tpm: tis: add support for MMIO TPM on SynQuacer

On Thu, 23 Jan 2020 at 13:27, Jarkko Sakkinen
<jarkko.sakkinen@...ux.intel.com> wrote:
>
> On Tue, 2020-01-14 at 15:16 +0100, Ard Biesheuvel wrote:
> > When fitted, the SynQuacer platform exposes its SPI TPM via a MMIO
> > window that is backed by the SPI command sequencer in the SPI bus
> > controller. This arrangement has the limitation that only byte size
> > accesses are supported, and so we'll need to provide a separate set
> > of read and write accessors that take this into account.
>
> What is SynQuacer platform?
>

It is an arm64 SoC manufactured by Socionext.

> I'm also missing a resolution why tpm_tis.c is extended to handle both
> and not add tpm_tis_something.c instead. It does not follow the pattern
> we have in place (e.g. look up tpm_tis_spi.c).
>

We could easily do that instead, if preferred. It's just that it would
duplicate a bit of code.