linux-kernel - Re: [PATCH v3 1/4] dt-bindings: power: reset: add document for reboot-mode driver

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Date:	Thu, 4 Feb 2016 17:08:14 -0600
From:	Rob Herring <robh@...nel.org>
To:	Andy Yan <andy.yan@...k-chips.com>
Cc:	arnd@...db.de, john.stultz@...aro.org, moritz.fischer@...us.com,
	matthias.bgg@...il.com, galak@...eaurora.org,
	ijc+devicetree@...lion.org.uk, catalin.marinas@....com,
	heiko@...ech.de, sre@...nel.org, dbaryshkov@...il.com,
	alexandre.belloni@...e-electrons.com, jun.nie@...aro.org,
	pawel.moll@....com, will.deacon@....com,
	linux-rockchip@...ts.infradead.org, wxt@...k-chips.com,
	devicetree@...r.kernel.org, linux-pm@...r.kernel.org,
	linux@....linux.org.uk, mbrugger@...e.com,
	linux-arm-kernel@...ts.infradead.org, lorenzo.pieralisi@....com,
	linux-kernel@...r.kernel.org, richard@....at, dwmw2@...radead.org,
	mark.rutland@....com
Subject: Re: [PATCH v3 1/4] dt-bindings: power: reset: add document for
 reboot-mode driver

On Tue, Feb 02, 2016 at 05:59:11PM +0800, Andy Yan wrote:
> add device tree bindings document for reboot-mode driver
> 
> Signed-off-by: Andy Yan <andy.yan@...k-chips.com>
> 
> ---
> 
> Changes in v3:
> - descirbe all reboot mode as properity instead of subnode
> 
> Changes in v2: None
> Changes in v1: None
> 
>  .../bindings/power/reset/reboot-mode.txt           | 26 ++++++++++++++++
>  .../bindings/power/reset/syscon-reboot-mode.txt    | 36 ++++++++++++++++++++++
>  2 files changed, 62 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/power/reset/reboot-mode.txt
>  create mode 100644 Documentation/devicetree/bindings/power/reset/syscon-reboot-mode.txt
> 
> diff --git a/Documentation/devicetree/bindings/power/reset/reboot-mode.txt b/Documentation/devicetree/bindings/power/reset/reboot-mode.txt
> new file mode 100644
> index 0000000..517080f
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/power/reset/reboot-mode.txt
> @@ -0,0 +1,26 @@
> +Generic reboot mode core map driver
> +
> +This driver get reboot mode arguments and call the write
> +interface to stores the magic value in special register
> +or ram . Then the bootloader can read it and take different
> +action according the argument stored.
> +
> +All mode properties are vendor specific, it is a indication to tell

The values should be vendor specific. The property names should not. We 
can allow vendor specific ones, but we need to have a common set.

> +the bootloder what to do when the system reboot, and should be named
> +as mode-xxx = <magic> (xxx is mode name).
> +
> +- mode-normal: Normal reboot mode, system reboot with command "reboot".
> +- mode-recovery: Android Recovery mode, it is a mode to format the device or update a new image.
> +- mode-fastboot: Android fastboot mode, it's a mode to  re-flash partitions on the device.
> +- mode-loader: A bootloader mode, it's a mode used to download image on Rockchip platform,
> +	       usually used in development.
> +- mode-maskrom: It's a mode to download bootloader on Rockchip platform.
> +
> +Example:
> +	reboot-mode {
> +		mode-normal = <BOOT_NORMAL>;
> +		mode-recovery = <BOOT_RECOVERY>;
> +		mode-fastboot = <BOOT_FASTBOOT>;

I tend to agree with John on calling this mode-bootloader.

OTOH, fastboot is more specific about what the mode is. The name in DT 
and the userspace name don't necessarily have to be the same.

> +		mode-loader = <BOOT_LOADER>;

This one needs a better name. Maybe it should be 'rockchip,mode-loader' 
as it is vendor specific. Either way, loader is vague. Perhaps 
rockchip,mode-bl-download?

> +		mode-maskrom = <BOOT_MASKROM>;

I think this should be "mode-rom-download".

> +	}
> diff --git a/Documentation/devicetree/bindings/power/reset/syscon-reboot-mode.txt b/Documentation/devicetree/bindings/power/reset/syscon-reboot-mode.txt
> new file mode 100644
> index 0000000..923c82b
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/power/reset/syscon-reboot-mode.txt
> @@ -0,0 +1,36 @@
> +SYSCON reboot mode driver
> +
> +This driver get reboot mode magic value form reboot-mode driver
> +and stores it in a SYSCON mapped register. Then the bootloader
> +can read it and take different action according to the magic
> +value stored.
> +
> +This DT node should be represented as a sub-node of a "syscon", "simple-mfd"
> +node.

Whether or not it is a simple-mfd or not depends on the syscon node.

> +
> +Required properties:
> +- compatible: should be "syscon-reboot-mode"
> +- offset: offset in the register map for the storage register (in bytes)
> +
> +Optional properity:
> +- mask: the mask bits of the mode magic value, default set to 0xffffffff if missing.
> +
> +The rest of the properties should follow the generic reboot-mode discription
> +found in reboot-mode.txt
> +
> +Example:
> +	pmu: pmu@...04000 {
> +		compatible = "rockchip,rk3066-pmu", "syscon", "simple-mfd";
> +		reg = <0x20004000 0x100>;
> +
> +		reboot-mode {
> +			compatible = "syscon-reboot-mode";
> +			offset = <0x40>;
> +			mode-normal = <BOOT_NORMAL>;
> +			mode-recovery = <BOOT_RECOVERY>;
> +			mode-fastboot = <BOOT_FASTBOOT>;
> +			mode-loader = <BOOT_LOADER>;
> +			mode-maskrom = <BOOT_MASKROM>;
> +
> +		};
> +	};
> -- 
> 1.9.1
> 
> 
> --
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