From mboxrd@z Thu Jan  1 00:00:00 1970
From: Vaibhav Hiremath <vaibhav.hiremath@linaro.org>
Subject: Re: [PATCH 10/10] i2c: dt: describe generic bindings
Date: Sun, 09 Aug 2015 15:21:33 +0530
Message-ID: <55C722A5.4020403@linaro.org>
References: <1439066007-13951-1-git-send-email-wsa@the-dreams.de> <1439066007-13951-11-git-send-email-wsa@the-dreams.de>
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To: Wolfram Sang <wsa@the-dreams.de>, linux-i2c@vger.kernel.org
Cc: linux-sh@vger.kernel.org, Magnus Damm <magnus.damm@gmail.com>, Simon Horman <horms@verge.net.au>, Laurent Pinchart <laurent.pinchart@ideasonboard.com>, Geert Uytterhoeven <geert@linux-m68k.org>, Andrey Danin <danindrey@mail.ru>, Stephen Warren <swarren@wwwdotorg.org>
List-Id: linux-i2c@vger.kernel.org



On Sunday 09 August 2015 02:03 AM, Wolfram Sang wrote:
> From: Wolfram Sang <wsa+renesas@sang-engineering.com>
>
> Start a new file which describes the generic bindings used for I2C with
> device tree. So we have a central place to look for them, increase
> visibility of them, and hopefully reduce the amount of custom properties
> introduced.
>
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
> ---
>   Documentation/devicetree/bindings/i2c/i2c.txt | 33 +++++++++++++++++++++++++++
>   1 file changed, 33 insertions(+)
>   create mode 100644 Documentation/devicetree/bindings/i2c/i2c.txt
>
> diff --git a/Documentation/devicetree/bindings/i2c/i2c.txt b/Documentation/devicetree/bindings/i2c/i2c.txt
> new file mode 100644
> index 00000000000000..1175efed4a41b5
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/i2c/i2c.txt
> @@ -0,0 +1,33 @@
> +Generic device tree bindings for I2C busses
> +===========================================
> +
> +This document describes generic bindings which can be used to describe I2C
> +busses in a device tree.
> +
> +Required properties
> +-------------------
> +
> +- #address-cells  - should be <1>. Read more about addresses below.
> +- #size-cells     - should be <0>.
> +- compatible      - name of I2C bus controller following generic names
> +		    recommended practice.
> +
> +For other required properties e.g. to describe register sets, interrupts,
> +clocks, etc. check the binding documentation of the specific driver.
> +
> +The cells properties above define that an address of children of an I2C bus
> +are described by a single value. This is usually a 7 bit address. However,
> +flags can be attached to the address. I2C_TEN_BIT_ADDRESS is used to mark a 10
> +bit address. It is needed to avoid the ambiguity between e.g. a 7 bit address
> +of 0x50 and a 10 bit address of 0x050 which, in theory, can be on the same bus.
> +Another flag is I2C_OWN_SLAVE_ADDRESS to mark addresses on which we listen to
> +be devices ourselves.
> +
> +Optional properties
> +-------------------
> +
> +These properties may not be supported by all drivers. However, if a driver
> +wants to support one of the below features, it should adapt the bindings below.
> +
> +- clock-frequency	- frequency of bus clock in Hz
> +- wakeup-source		- device can be used as a wakeup source.
>

Thanks for the patch and it looks good to me.

Shouldn't we also update/add other generic optional properties?
For example,

  - i2c-sclk-low-time-ns
  - i2c-sclk-high-time-ns
  - etc...


We need to consolidate all such generic properties in here.

Thanks,
Vaibhav