From: Rob Herring <robh@kernel.org>
To: Amir Mizinski <amirmizi6@gmail.com>
Cc: Eyal.Cohen@nuvoton.com,
Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
Oshri Alkobi <oshrialkoby85@gmail.com>,
Alexander Steffen <alexander.steffen@infineon.com>,
Mark Rutland <mark.rutland@arm.com>,
Peter Huewe <peterhuewe@gmx.de>, Jason Gunthorpe <jgg@ziepe.ca>,
Arnd Bergmann <arnd@arndb.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
benoit.houyere@st.com, Eddie James <eajames@linux.ibm.com>,
Joel Stanley <joel@jms.id.au>,
devicetree@vger.kernel.org,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
linux-integrity@vger.kernel.org,
IS20 Oshri Alkoby <oshri.alkoby@nuvoton.com>,
Tomer Maimon <tmaimon77@gmail.com>,
gcwilson@us.ibm.com, kgoldman@us.ibm.com,
IS30 Dan Morav <Dan.Morav@nuvoton.com>,
oren.tanami@nuvoton.com, shmulik.hager@nuvoton.com,
amir.mizinski@nuvoton.com
Subject: Re: [PATCH v7 6/7] tpm: Add YAML schema for TPM TIS I2C options
Date: Wed, 6 May 2020 14:02:57 -0500 [thread overview]
Message-ID: <CAL_JsqLEkoa1+nnWBQHah14_6BozkMzjcSpbk-hhLS=Rnqaa8Q@mail.gmail.com> (raw)
In-Reply-To: <c2760659-ec14-237e-e060-5d9a2d7c7e4a@gmail.com>
On Wed, May 6, 2020 at 10:20 AM Amir Mizinski <amirmizi6@gmail.com> wrote:
>
>
> On 2020-05-05 16:12, Rob Herring wrote:
> > On Mon, Apr 27, 2020 at 03:49:30PM +0300, amirmizi6@gmail.com wrote:
> >> From: Amir Mizinski <amirmizi6@gmail.com>
> >>
> >> Added a YAML schema to support tpm tis i2c related dt-bindings for the I2c
> >> PTP based physical layer.
> >>
> >> This patch adds the documentation for corresponding device tree bindings of
> >> I2C based Physical TPM.
> >> Refer to the 'I2C Interface Definition' section in
> >> 'TCG PC Client PlatformTPMProfile(PTP) Specification' publication
> >> for specification.
> >
> > Again, DT bindings describe h/w devices, not just a protocol. A device
> > is more than just a protocol interface. There's clocks, power rails,
> > resets, interrupts, firmware, etc.
> >
> > Unless there's something special about TPM chips that makes none of this
> > applicable and no chip will ever have any quirks (or extensions) in
> > their protocol to work-around, then you need compatible string(s) that
> > are specific to the TPM chip. You can have tcg,tpm-tis-i2c as a
> > fallback, but you need specific compatible to handle any quirks.
> >
> > Rob
>
> Hello Rob, currently yes. All TPM chip are implemented according to the TGC specs and should use the same properties for this I2C driver.
> I can't say for sure that it will be the case in the future.
Exactly. That's the issue. If you have just "tcg,tpm-tis-i2c" and need
to handle some difference in the future, then you can't without
updating the DT. You must be able to handle future issues without
updating the DT.
> Shouldn't we use the standard "tcg,tpm-tis-i2c" compatible, and if a specific TPM chip will deviate from the specs, the vendor should add an additional compatible string for it?
Name something where multiple vendors have implemented a spec and
there's no deviation. It simply doesn't exist. How would you know?
Does the TPM spec define all the things I listed above outside of just
the I2C protocol?
Also, what version of the spec is "tcg,tpm-tis-i2c"? Few specs have
only 1 version.
Rob
next prev parent reply other threads:[~2020-05-06 19:03 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-27 12:49 [PATCH v7 0/7] Add tpm i2c ptp driver amirmizi6
2020-04-27 12:49 ` [PATCH v7 1/7] tpm: tpm_tis: Make implementation of read16, read32 and write32 optional amirmizi6
2020-04-27 12:49 ` [PATCH v7 2/7] tpm: tpm_tis: Add verify_data_integrity handle toy tpm_tis_phy_ops amirmizi6
2020-04-29 5:34 ` Jarkko Sakkinen
2020-04-30 10:19 ` Amir Mizinski
2020-04-27 12:49 ` [PATCH v7 3/7] tpm: tpm_tis: Rewrite "tpm_tis_req_canceled()" amirmizi6
2020-04-29 5:37 ` Jarkko Sakkinen
2020-04-30 10:29 ` Amir Mizinski
2020-04-27 12:49 ` [PATCH v7 4/7] tpm: tpm_tis: Fix expected bit handling and send all bytes in one shot without last byte in exception amirmizi6
2020-04-27 12:49 ` [PATCH v7 5/7] tpm: Handle an exception for TPM Firmware Update mode amirmizi6
2020-04-27 12:49 ` [PATCH v7 6/7] tpm: Add YAML schema for TPM TIS I2C options amirmizi6
2020-05-05 16:12 ` Rob Herring
2020-05-06 15:20 ` Amir Mizinski
2020-05-06 19:02 ` Rob Herring [this message]
2020-04-27 12:49 ` [PATCH v7 7/7] tpm: tpm_tis: add tpm_tis_i2c driver amirmizi6
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