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SubjectRe: [PATCH v3 2/5] dt-bindings: soc: add document for rockchip reboot notifier driver
Date
Hi Andy,

Am Dienstag, 1. Dezember 2015, 23:10:15 schrieb Andy Yan:
> 2015-11-23 21:15 GMT+08:00 Andy Yan <andyshrk@gmail.com>:
> > 2015-11-20 9:58 GMT+08:00 Rob Herring <robh@kernel.org>:
> >> On Thu, Nov 19, 2015 at 7:16 PM, Andy Yan <andy.yan@rock-chips.com>
> >>
> >> wrote:
> >> > On 2015年11月19日 12:35, Heiko Stuebner wrote:
> >> >> Am Donnerstag, 19. November 2015, 09:17:37 schrieb Andy Yan:
> >> >>> 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).
> >> >>
> >> > 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?
> >>
> >> Add the data you need to the PMU node. Then the PMU driver can get it
> >> and pass to the child driver.
> >>
> >> Rob
> >> --
> >>
> > Do you mean I should implement the DT node like this?
> >
> > diff --git a/arch/arm/boot/dts/rk3xxx.dtsi
> >
> > b/arch/arm/boot/dts/rk3xxx.dtsi
> > index 7b14d7a..1735d09 100644
> > --- a/arch/arm/boot/dts/rk3xxx.dtsi
> > +++ b/arch/arm/boot/dts/rk3xxx.dtsi
> > @@ -103,12 +103,6 @@
> >
> > };
> >
> > };
> >
> > - reboot {
> > - compatible = "rockchip,reboot";
> > - rockchip,regmap = <&pmu>;
> > - offset = <0x40>;
> > - };
> > -
> >
> > xin24m: oscillator {
> >
> > compatible = "fixed-clock";
> > clock-frequency = <24000000>;
> >
> > @@ -249,7 +243,11 @@
> >
> > pmu: pmu@20004000 {
> >
> > compatible = "rockchip,rk3066-pmu", "syscon";
> >
> > - reg = <0x20004000 0x100>;
> > + reg = <0x20004000 0x100>;
> > + reboot {
> > + compatible = "rockchip,reboot";
> > + offset = <0x40>;
> > + };
> >
> > };
> >
> > diff --git a/arch/arm64/boot/dts/rockchip/rk3368.dtsi
> > b/arch/arm64/boot/dts/rockchip/rk3368.dtsi
> > index cd02229..8a9837a 100644
> > --- a/arch/arm64/boot/dts/rockchip/rk3368.dtsi
> > +++ b/arch/arm64/boot/dts/rockchip/rk3368.dtsi
> > @@ -202,12 +202,6 @@
> >
> > method = "smc";
> >
> > };
> >
> > - reboot {
> > - compatible = "rockchip,reboot";
> > - rockchip,regmap = <&pmugrf>;
> > - offset = <0x200>;
> > - };
> > -
> >
> > timer {
> >
> > compatible = "arm,armv8-timer";
> > interrupts = <GIC_PPI 13
> >
> > @@ -493,6 +487,10 @@
> >
> > pmugrf: syscon@ff738000 {
> >
> > compatible = "rockchip,rk3368-pmugrf", "syscon";

compatible = "rockchip,rk3368-pmugrf", "syscon", "simple-mfd";


> > reg = <0x0 0xff738000 0x0 0x1000>;
> >
> > + reboot {
> > + compatible = "rockchip,reboot";
> > + offset = <0x200>;
> > + };
> >
> > };
>
> Is there any further suggestion for this? If not, I will send the V4 with
> the DT node as a subnode in PMU or PMUGRF.

I guess Rob is the authority on this, but I'm not sure on the "devicetree
describes hardware" level.

On the one hand it is not really a hardware-device, but on the other hand it
is a firmware-interface (like psci etc, that's already in the devicetree
elsewhere), so I'd guess it should be ok.


Heiko


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