linux-kernel - RE: [PATCH v3 2/8] DT: reset: renesas,rzn1-reboot: document RZ/N1 reboot driver

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Message-ID: <OSBPR01MB2054DA948D0301F20AB9F1EDD2BE0@OSBPR01MB2054.jpnprd01.prod.outlook.com>
Date:   Tue, 10 Apr 2018 07:08:45 +0000
From:   Michel Pollet <michel.pollet@...renesas.com>
To:     Rob Herring <robh@...nel.org>
CC:     "linux-renesas-soc@...r.kernel.org" 
        <linux-renesas-soc@...r.kernel.org>,
        Simon Horman <horms@...ge.net.au>,
        Phil Edworthy <phil.edworthy@...esas.com>,
        Michel Pollet <buserror+upstream@...il.com>,
        Magnus Damm <magnus.damm@...il.com>,
        Mark Rutland <mark.rutland@....com>,
        Lee Jones <lee.jones@...aro.org>,
        Russell King <linux@...linux.org.uk>,
        "Sebastian Reichel" <sre@...nel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>
Subject: RE: [PATCH v3 2/8] DT: reset: renesas,rzn1-reboot: document RZ/N1
 reboot driver

Hi Rob,

On 09 April 2018 21:10,  Rob Herring wrote:
> On Thu, Mar 29, 2018 at 08:46:58AM +0100, Michel Pollet wrote:
> > The Renesas RZ/N1 Family (Part #R9A06G0xx) requires a driver as part
> > of the sysctrl MFD to handle rebooting the CA7 cores.
> > This documents the driver bindings.
> >
> > Signed-off-by: Michel Pollet <michel.pollet@...renesas.com>
> > ---
> >  .../bindings/power/renesas,rzn1-reboot.txt           | 20
> ++++++++++++++++++++
> >  1 file changed, 20 insertions(+)
> >  create mode 100644
> > Documentation/devicetree/bindings/power/renesas,rzn1-reboot.txt
> >
> > diff --git
> > a/Documentation/devicetree/bindings/power/renesas,rzn1-reboot.txt
> > b/Documentation/devicetree/bindings/power/renesas,rzn1-reboot.txt
> > new file mode 100644
> > index 0000000..f592769
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/power/renesas,rzn1-
> reboot.txt
> > @@ -0,0 +1,20 @@
> > +DT bindings for the Renesas RZ/N1 Reboot Driver
> > +
> > +== Reboot Driver Node ==
> > +
> > +The reboot driver is always a subnode of the system controller node,
> > +see renesas,rzn1-sysctrl.txt for details.
> > +
> > +Bindings:
> > ++ Required:
> > +compatible = "renesas,rzn1-reboot";
> > +
> > +Example:
> > +sysctrl: sysctrl@...0c000 {
> > +compatible = "renesas,rzn1-sysctrl", "syscon", "simple-mfd";
>
> Are there other functions for this block? If so, please define a complete
> binding for the block.

There are indeed multiple functions for this particular IP block. It's pretty much a
kitchen sink of clocks, pinmux, reboot, watchdog, SMP and probably a couple
more I forgot about!

We've discussed this MFD structure with Geert, we picked that because if I
were to add all these callbacks/drivers to a 'sysctrl' driver, it'd end up looking
like ... a mach-xx.c file in the end!
So the current version is just a placeholder for a single driver for now, but it
won't last, there's already a SMP core enable driver lined up next...

>
> > +reg = <0x4000c000 0x1000>;
> > +
> > +reboot {
> > +compatible = "renesas,rzn1-reboot";
>
> Why is this node needed? The driver for "renesas,rzn1-sysctrl" should be
> able to register as a reboot handler/driver/provider.

Please see above...

>
> Rob

Thanks for your input!
Michel




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