linux-kernel - Re: [PATCH v6] char: tpm: add i2c driver for cr50

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Message-ID: <87v9d4baxo.fsf@collabora.com>
Date:   Mon, 14 Dec 2020 18:37:55 +0200
From:   Adrian Ratiu <adrian.ratiu@...labora.com>
To:     Jarkko Sakkinen <jarkko@...nel.org>,
        Adrian Ratiu <adrian.ratiu@...labora.com>
Cc:     linux-integrity@...r.kernel.org, Peter Huewe <peterhuewe@....de>,
        Jason Gunthorpe <jgg@...pe.ca>, linux-kernel@...r.kernel.org,
        kernel@...labora.com,
        "dlaurie@...omium.org" <dlaurie@...omium.org>,
        Helen Koike <helen.koike@...labora.com>,
        Ezequiel Garcia <ezequiel@...labora.com>
Subject: Re: [PATCH v6] char: tpm: add i2c driver for cr50

On Fri, 11 Dec 2020, Jarkko Sakkinen <jarkko@...nel.org> wrote:
> On Wed, Dec 09, 2020 at 02:41:45PM +0200, Adrian Ratiu wrote: 
>> On Tue, 08 Dec 2020, Jarkko Sakkinen <jarkko@...nel.org> wrote: 
>> > On Mon, Dec 07, 2020 at 04:20:16PM +0200, Adrian Ratiu wrote: 
>> > > From: "dlaurie@...omium.org" <dlaurie@...omium.org>  Add 
>> > > TPM 2.0 compatible I2C interface for chips with cr50 
>> > > firmware. The firmware running on the currently supported 
>> > > H1 MCU requires a special driver to handle its specific 
>> > > protocol, and this makes it unsuitable to use 
>> > > tpm_tis_core_* and instead it must implement the underlying 
>> > > TPM protocol similar to the other I2C TPM drivers.   - All 
>> > > 4 bytes of status register must be read/written at once.  - 
>> > > FIFO and burst count is limited to 63 and must be drained 
>> > > by AP.  - Provides an interrupt to indicate when read 
>> > > response data is ready and when the TPM is finished 
>> > > processing write data.   This driver is based on the 
>> > > existing infineon I2C TPM driver, which most closely 
>> > > matches the cr50 i2c protocol behavior. 
>> >  Starts to look legit. Has anyone tested this? 
>>  I tested on an x86_64 Chromebook EVE (aka Google Pixelbook) by 
>> chainloading in legacy mode and booting into a Yocto-based 
>> userspace (meta-chromebook) where I used tpm2-tools to 
>> communicate with the chip and also built and tested a 
>> ChromiumOS userspace in developer mode.   I do not have access 
>> to other HW which has this chip, so it is about as much testing 
>> I can do to confirm the driver works on this HW.   Adrian 
> 
> So can you respond to this with tested-by. It's sufficient 
> because collateral effects of driver failing are insignificant 
> for the kernel as whole. 

Tested-by: Adrian Ratiu <adrian.ratiu@...labora.com>

>  
>  /Jarkko