linux-kernel - Re: [PATCH v3 0/2] ftpm: a firmware based TPM driver

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Date:   Wed, 8 May 2019 10:11:54 +0530
From:   Sumit Garg <sumit.garg@...aro.org>
To:     Sasha Levin <sashal@...nel.org>
Cc:     peterhuewe@....de, jarkko.sakkinen@...ux.intel.com, jgg@...pe.ca,
        corbet@....net,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-doc@...r.kernel.org, linux-integrity@...r.kernel.org,
        linux-kernel@...rosoft.com, thiruan@...rosoft.com,
        bryankel@...rosoft.com, tee-dev@...ts.linaro.org
Subject: Re: [PATCH v3 0/2] ftpm: a firmware based TPM driver

+ TEE ML

Hi Sasha,

Firstly apologies for my comments here as I recently joined
linux-integrity ML so I don't have other patches in my inbox. Also, it
would be nice if you could cc TEE ML in future patches, so that people
are aware of such interesting use-cases and may provide some feedback.

On Tue, 7 May 2019 at 23:10, Sasha Levin <sashal@...nel.org> wrote:
>
> On Mon, Apr 15, 2019 at 11:56:34AM -0400, Sasha Levin wrote:
> >From: "Sasha Levin (Microsoft)" <sashal@...nel.org>
> >
> >Changes since v2:
> >
> > - Drop the devicetree bindings patch (we don't add any new ones).
> > - More code cleanups based on Jason Gunthorpe's review.
> >
> >Sasha Levin (2):
> >  ftpm: firmware TPM running in TEE
> >  ftpm: add documentation for ftpm driver
>
> Ping? Does anyone have any objections to this?
>

>From [PATCH v3 1/2] ftpm: firmware TPM running in TEE:

> +static const struct of_device_id of_ftpm_tee_ids[] = {
> + { .compatible = "microsoft,ftpm" },
> + { }
> +};
> +MODULE_DEVICE_TABLE(of, of_ftpm_tee_ids);
> +
> +static struct platform_driver ftpm_tee_driver = {
> + .driver = {
> + .name = DRIVER_NAME,
> + .of_match_table = of_match_ptr(of_ftpm_tee_ids),
> + },
> + .probe = ftpm_tee_probe,
> + .remove = ftpm_tee_remove,
> +};
> +
> +module_platform_driver(ftpm_tee_driver);

Here this fTPM driver (seems to communicate with OP-TEE based TA)
should register on TEE bus [1] rather than platform bus as its actual
dependency is on TEE driver rather than using deferred probe to meet
its dependency. Have a look at OP-TEE based RNG driver here [2].

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=0fc1db9d105915021260eb241661b8e96f5c0f1a
[2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=5fe8b1cc6a03c46b3061e808256d39dcebd0d0f0

-Sumit

> --
> Thanks,
> Sasha