Re: [PATCH v3 2/5] dt-bindings: soc: add document for rockchip reboot notifier driver

From: Andy Yan
Date: Thu Nov 19 2015 - 20:17:19 EST

Hi Heiko:

On 2015å11æ19æ 12:35, Heiko Stuebner wrote:
Hi Andy,

Am Donnerstag, 19. November 2015, 09:17:37 schrieb Andy Yan:
Hi Rob:

On 2015å11æ19æ 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
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


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).


Thanks for your suggestion.
I have read the code you list above, if we implement the reboot notifier
driver like this, the driver need to add much more code to find the platform
data(like arch/arm/mach-rockhcip/pm.c), what's more, if we have a new soc
in the future and the soc use a different register here, we need modify the
driver to add a new platform data again, this will bring additional work.

Use the DT node pass the register will make the driver code simple and clear.
Is there any hurt to put this information in the DT?


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