From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1751089AbcGQN2H (ORCPT <rfc822;w@1wt.eu>);
	Sun, 17 Jul 2016 09:28:07 -0400
Received: from mail-oi0-f67.google.com ([209.85.218.67]:33886 "EHLO
	mail-oi0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1750852AbcGQN2F (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Sun, 17 Jul 2016 09:28:05 -0400
Date: Sun, 17 Jul 2016 08:28:01 -0500
From: Rob Herring <robh@kernel.org>
To: Andrey Pronin <apronin@chromium.org>
Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
        Peter Huewe <peterhuewe@gmx.de>, Marcel Selhorst <tpmdd@selhorst.net>,
        Jason Gunthorpe <jgunthorpe@obsidianresearch.com>,
        tpmdd-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org,
        groeck@chromium.org, smbarber@chromium.org, dianders@chromium.org,
        devicetree@vger.kernel.org,
        =?iso-8859-1?B?oKCgUGF3ZWw=?= Moll <pawel.moll@arm.com>,
        =?iso-8859-1?B?oKCgTWFyaw==?= Rutland <mark.rutland@arm.com>,
        =?iso-8859-1?B?oKCgSWFu?= Campbell 
	<ijc+devicetree@hellion.org.uk>,
        =?iso-8859-1?B?oKCgS3VtYXI=?= Gala <galak@codeaurora.org>
Subject: Re: [PATCH 1/2] tpm: devicetree: document properties for cr50
Message-ID: <20160717132801.GA5527@rob-hp-laptop>
References: <1468549218-19215-1-git-send-email-apronin@chromium.org>
 <1468549218-19215-2-git-send-email-apronin@chromium.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <1468549218-19215-2-git-send-email-apronin@chromium.org>
User-Agent: Mutt/1.5.24 (2015-08-30)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Thu, Jul 14, 2016 at 07:20:17PM -0700, Andrey Pronin wrote:
> Add TPM2.0-compatible interface to Cr50. Document its properties
> in devicetree.
> 
> Signed-off-by: Andrey Pronin <apronin@chromium.org>
> ---
>  .../devicetree/bindings/security/tpm/cr50_spi.txt  | 30 ++++++++++++++++++++++
>  1 file changed, 30 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/security/tpm/cr50_spi.txt
> 
> diff --git a/Documentation/devicetree/bindings/security/tpm/cr50_spi.txt b/Documentation/devicetree/bindings/security/tpm/cr50_spi.txt
> new file mode 100644
> index 0000000..1b05e51
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/security/tpm/cr50_spi.txt
> @@ -0,0 +1,30 @@
> +* Cr50 Chip on SPI.
> +
> +TCG PTP FIFO Compliant Interface to Cr50 on SPI bus.
> +
> +Required properties:
> +- compatible: Should be "google,cr50_spi".

I agree with dropping '_spi'. The interface is defined by the parent 
device.

> +- spi-max-frequency: Maximum SPI frequency.
> +
> +Optional properties:
> +- access-delay-msec: Required delay between subsequent transactions on SPI.

There may be a standard property for this...

> +- sleep-delay-msec: Time after the last SPI activity, after which the chip
> +  may go to sleep.
> +- wake-start-delay-msec: Time after initiating wake up before the chip is
> +  ready to accept commands over SPI.

Use the standard unit '-ms' instead of '-msec'.

Do these times really vary much and need to be in DT?