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

From: Oshri Alkobi <oshrialkoby85@gmail.com>
To: Alexander Steffen <Alexander.Steffen@infineon.com>
Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
	robh+dt@kernel.org, mark.rutland@arm.com, peterhuewe@gmx.de,
	jgg@ziepe.ca, arnd@arndb.de, gregkh@linuxfoundation.org,
	oshri.alkoby@nuvoton.com, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org,
	gcwilson@us.ibm.com, kgoldman@us.ibm.com,
	nayna@linux.vnet.ibm.com, dan.morav@nuvoton.com,
	tomer.maimon@nuvoton.com
Subject: Re: [PATCH v2 0/2] char: tpm: add new driver for tpm i2c ptp
Date: Thu, 4 Jul 2019 12:48:20 -0500	[thread overview]
Message-ID: <CAM9mBwJC2QD5-gV1eJUDzC2Fnnugr-oCZCoaH2sT_7ktFDkS-Q@mail.gmail.com> (raw)
In-Reply-To: <79e8bfd2-2ed1-cf48-499c-5122229beb2e@infineon.com>

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Alex, Jarkko, thank you very much for your feedbacks!

> The long descriptions are still missing

Will be expanded

> 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.

I totally agree, there are some duplications that can be common, indeed it
will require some work in tpm_tis_core.

Since I believe it is not going to happen soon, I would suggest to examine
what duplications can currently be dropped from the new driver, so the
kernel will support the PTP I2C interface in the meantime.

I will appreciate getting ideas about any tpm_tis_core logic that currently
can be used as is by the new drive.

> 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

Since the TIS is an old specification that mostly defines FIFO for TPM1.2 I
would say the name tpm_tis_i2c does not completely reflect its goal.
However we really don't have any problem with any name that the group will
agree on.

Does tpm_ptp_i2c sound better than the current name?

Oshri

On Thu, Jul 4, 2019 at 6:29 AM Alexander Steffen <
Alexander.Steffen@infineon.com> wrote:

> 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
>

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