Re: [PATCH v1 1/6] dt-bindings: misc: add document for reboot-mode driver

From: Rob Herring <robh@kernel.org>
To: Andy Yan <andy.yan@rock-chips.com>
Cc: heiko@sntech.de, arnd@arndb.de, john.stultz@linaro.org,
	sjg@chromium.org, alexandre.belloni@free-electrons.com,
	treding@nvidia.com, galak@codeaurora.org,
	ijc+devicetree@hellion.org.uk, wxt@rock-chips.com,
	catalin.marinas@arm.com, olof@lixom.net, geert+renesas@glider.be,
	linux-rockchip@lists.infradead.org, dbaryshkov@gmail.com,
	sre@kernel.org, jun.nie@linaro.org, pawel.moll@arm.com,
	will.deacon@arm.com, akpm@linux-foundation.org,
	devicetree@vger.kernel.org, linux@arm.linux.org.uk,
	gregkh@linuxfoundation.org, joel@jms.id.au,
	linux-arm-kernel@lists.infradead.org, lorenzo.pieralisi@arm.com,
	khilman@linaro.org, moritz.fischer@ettus.com,
	linux-kernel@vger.kernel.org, mark.rutland@arm.com
Subject: Re: [PATCH v1 1/6] dt-bindings: misc: add document for reboot-mode driver
Date: Tue, 22 Dec 2015 18:32:17 -0600	[thread overview]
Message-ID: <20151223003217.GA18700@rob-hp-laptop> (raw)
In-Reply-To: <1450775124-23966-1-git-send-email-andy.yan@rock-chips.com>

On Tue, Dec 22, 2015 at 05:05:24PM +0800, Andy Yan wrote:
> add device tree bindings document for reboot-mode driver
> 
> Signed-off-by: Andy Yan <andy.yan@rock-chips.com>
> 
> ---
> 
> Changes in v1: None
> 
>  .../devicetree/bindings/misc/reboot-mode.txt       | 41 ++++++++++++++++++++++
>  1 file changed, 41 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/misc/reboot-mode.txt
> 
> diff --git a/Documentation/devicetree/bindings/misc/reboot-mode.txt b/Documentation/devicetree/bindings/misc/reboot-mode.txt
> new file mode 100644
> index 0000000..082bc0c
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/misc/reboot-mode.txt
> @@ -0,0 +1,41 @@
> +Generic reboot mode communication driver

You're not describing a driver. It is a mapping of boot modes to values.
> +
> +This driver get reboot mode arguments from userspace

Coming from userspace is a Linuxism.

> +and stores it in special register or ram . Then the
> +bootloader will read it and take different action
> +according the argument stored.
> +
> +Required properties:
> +        - compatible = "reboot-mode" or other vendor compatible string;
> +
> +Each mode is represented as a sub-node of reboot_mode:
> +
> +Subnode required properties:
> +        - linux,mode: reboot mode command,such as "loader","recovery", "fastboot".
> +        - linux,magic: magic number for the mode, this is vendor specific.
> +
> +example:
> +	reboot_mode {
> +		compatible = "rockchip,reboot-mode";
> +		rockchip,regmap = <&pmu>;
> +		offset = <0x40>;
> +		loader {
> +			linux,mode = "loader";
> +			linux,magic = <0x5242C301>;
> +		};

These can be much more simply expressed as:

loader = <0x5242c301>;

I would like to see the property names here standardized as much as
possible. I'm not sure if we can define the properties as a u32 or need
some flexibility here.

Rob