From: Heiko Stuebner <heiko@sntech.de>
To: Andy Yan <andy.yan@rock-chips.com>
Cc: Rob Herring <robh@kernel.org>, linux-kernel@vger.kernel.org,
        devicetree@vger.kernel.org, galak@codeaurora.org,
        linux@arm.linux.org.uk, linux-rockchip@lists.infradead.org,
        ijc+devicetree@hellion.org.uk, pawel.moll@arm.com,
        mark.rutland@arm.com, linux-arm-kernel@lists.infradead.org,
        khilman@linaro.org, treding@nvidia.com, wxt@rock-chips.com,
        sjg@chromium.org, benchan@google.com
Subject: Re: [PATCH v3 2/5] dt-bindings: soc: add document for rockchip reboot notifier driver
Date: Thu, 19 Nov 2015 05:35:48 +0100
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Hi Andy,

Am Donnerstag, 19. November 2015, 09:17:37 schrieb Andy Yan:
> Hi Rob:
> 
> On 2015年11月19日 06:59, Rob Herring wrote:
> > On Wed, Nov 18, 2015 at 05:53:30PM +0800, Andy Yan wrote:
> >> Add devicetree binding document for rockchip reboot nofifier driver
> > Just reading the subject this is way too specific to the Linux driver
> > needs rather than a h/w description. Please don't create fake DT nodes
> > just to bind to drivers. Whatever &pmu is is probably what should have
> > the DT node. Let the driver for it create child devices if you need
> > that.
> 
>      This is note a fake DT nodes, we really need it to tell the driver
>       which register to use to store the reboot mode. Because rockchip
>       use different register file to store the reboot mode on different
>       platform, on rk3066,rk3188, rk3288,it use  one of the PMU 
> register, on
>       the incoming RK3036, it use one of the GRF register, and it use 
> one  of
>       the PMUGRF register for arm64 platform rk3368. On the other hand, the
>       PMU/GRF/PMUGRF register file are mapped as "syscon", then referenced
>       by other DT nodes by phandle. So maybe let it as a separate DT 
> node here
>       is better.

or alternatively we could do something similar to what the bl-switcher 
cupfreq-driver does. Take a look at

drivers/cpufreq/arm_big_little.c
drivers/clk/clk-mb86s7x.c

We already have the core restart-handler code in the clock-tree, so could 
maybe simply do the
	platform_device_register_simple("rockchip-reboot", -1, NULL, 0);
in that common code?

Though I'm not yet sure how to get the platform-data. I guess one option would 
be to do things like the 3288 suspend code does (arch/arm/mach-rockchip/pm.c 
at the bottom), by having the per-soc-data in the driver and then matching 
against the pmu. Because the pmu is not part of the clock controller binding 
(and probably also shouldn't be).


Heiko


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