linux-kernel - Re: [PATCH 1/1] Add TPM 2.0 compatible I2C interface for chips with cr50 firmware.

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Message-ID: <20200225114728.GA15662@linux.intel.com>
Date:   Tue, 25 Feb 2020 13:47:28 +0200
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Fabien Lahoudere <fabien.lahoudere@...labora.com>
Cc:     swboyd@...omium.org, kernel@...labora.com,
        Duncan Laurie <dlaurie@...omium.org>,
        Peter Huewe <peterhuewe@....de>,
        Jason Gunthorpe <jgg@...pe.ca>, Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, linux-integrity@...r.kernel.org
Subject: Re: [PATCH 1/1] Add TPM 2.0 compatible I2C interface for chips with
 cr50 firmware.

On Tue, Feb 25, 2020 at 12:08:07PM +0100, Fabien Lahoudere wrote:
> 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 byes 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.  The driver is
> intentionally kept very similar in structure and style to the
> corresponding drivers in coreboot and depthcharge.
> 
> Signed-off-by: Duncan Laurie <dlaurie@...omium.org>
> [swboyd@...omium.org: Depend on i2c even if it's a module, replace
> boilier plate with SPDX tag, drop asm/byteorder.h include, simplify
> return from probe]
> Signed-off-by: Stephen Boyd <swboyd@...omium.org>
> Signed-off-by: Fabien Lahoudere <fabien.lahoudere@...labora.com>

The code quality looks overally decent, checkpatch.pl does not complain
and neither does sparse.

My only concern is the lack of tested-by's.

/Jarkko