linux-kernel - Re: [PATCH v2 6/6] tpm: Add driver for cr50 on I2C

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Date:   Fri, 2 Aug 2019 23:44:46 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Stephen Boyd <swboyd@...omium.org>
Cc:     Peter Huewe <peterhuewe@....de>,
        Duncan Laurie <dlaurie@...omium.org>,
        linux-kernel@...r.kernel.org, Jason Gunthorpe <jgg@...pe.ca>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-integrity@...r.kernel.org,
        Andrey Pronin <apronin@...omium.org>,
        Guenter Roeck <groeck@...omium.org>
Subject: Re: [PATCH v2 6/6] tpm: Add driver for cr50 on I2C

On Tue, Jul 16, 2019 at 03:45:18PM -0700, Stephen Boyd wrote:
> From: Duncan Laurie <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 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>

Apologies. I missed this when I stated my comment about SPI.

/Jarkko