linux-kernel - Re: [PATCH v2 0/2] char: tpm: add new driver for tpm i2c ptp

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Date:   Thu, 4 Jul 2019 13:29:41 +0200
From:   Alexander Steffen <Alexander.Steffen@...ineon.com>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        Oshri Alkoby <oshrialkoby85@...il.com>, <robh+dt@...nel.org>,
        <mark.rutland@....com>, <peterhuewe@....de>, <jgg@...pe.ca>,
        <arnd@...db.de>, <gregkh@...uxfoundation.org>,
        <oshri.alkoby@...oton.com>
CC:     <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-integrity@...r.kernel.org>, <gcwilson@...ibm.com>,
        <kgoldman@...ibm.com>, <nayna@...ux.vnet.ibm.com>,
        <dan.morav@...oton.com>, <tomer.maimon@...oton.com>
Subject: Re: [PATCH v2 0/2] char: tpm: add new driver for tpm i2c ptp

On 04.07.2019 10:43, Jarkko Sakkinen wrote:
> Check out tpm_tis_core.c and tpm_tis_spi.c. TPM TIS driver implements
> that spec so you should only implement a new physical layer.

I had the same thought. Unfortunately, the I2C-TIS specification 
introduces two relevant changes compared to tpm_tis/tpm_tis_spi:

1. Locality is not encoded into register addresses anymore, but stored 
in a separate register.
2. Several register addresses have changed (but still contain compatible 
contents).

I'd still prefer not to duplicate all the high-level logic from 
tpm_tis_core. But this will probably mean to introduce some new 
interfaces between tpm_tis_core and the physical layers.

Also, shouldn't the new driver be called tpm_tis_i2c, to group it with 
all the other (TIS) drivers, that implement a vendor-independent 
protocol? With tpm_i2c_ptp users might assume that ptp is just another 
vendor.

Alexander