Re: [PATCH v5 1/3] dt-bindings: reset: microchip sparx5 reset driver bindings
From: Steen Hegelund
Date: Tue Feb 16 2021 - 03:34:03 EST
Hi Alex,
On Mon, 2021-02-15 at 18:32 +0100, Alexandre Belloni wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you
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> On 10/02/2021 10:19:50+0100, Steen Hegelund wrote:
> > Document the Sparx5 reset device driver bindings
> >
> > The driver uses two IO ranges on sparx5 for access to
> > the reset control and the reset status.
> >
> > Signed-off-by: Steen Hegelund <steen.hegelund@xxxxxxxxxxxxx>
> > ---
> > .../bindings/reset/microchip,rst.yaml | 55
> > +++++++++++++++++++
> > 1 file changed, 55 insertions(+)
> > create mode 100644
> > Documentation/devicetree/bindings/reset/microchip,rst.yaml
> >
> > diff --git
> > a/Documentation/devicetree/bindings/reset/microchip,rst.yaml
> > b/Documentation/devicetree/bindings/reset/microchip,rst.yaml
> > new file mode 100644
> > index 000000000000..80046172c9f8
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/reset/microchip,rst.yaml
> > @@ -0,0 +1,55 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: "http://devicetree.org/schemas/reset/microchip,rst.yaml#"
> > +$schema: "http://devicetree.org/meta-schemas/core.yaml#"
> > +
> > +title: Microchip Sparx5 Switch Reset Controller
> > +
> > +maintainers:
> > + - Steen Hegelund <steen.hegelund@xxxxxxxxxxxxx>
> > + - Lars Povlsen <lars.povlsen@xxxxxxxxxxxxx>
> > +
> > +description: |
> > + The Microchip Sparx5 Switch provides reset control and
> > implements the following
> > + functions
> > + - One Time Switch Core Reset (Soft Reset)
> > +
> > +properties:
> > + $nodename:
> > + pattern: "^reset-controller@[0-9a-f]+$"
> > +
> > + compatible:
> > + const: microchip,sparx5-switch-reset
> > +
> > + reg:
> > + items:
> > + - description: cpu block registers
> > + - description: global control block registers
> > +
> > + reg-names:
> > + items:
> > + - const: cpu
> > + - const: gcb
> > +
>
> I still think this is not right because then you will be mapping the
> same set of register using multiple drivers without any form of
> synchronisation which will work because you are mapping the region
> without requesting it. But this may lead to issues later.
>
> At least, you should make cpu start at 0x80 and of size 4. Else, you
> won't be able to define and use the GPRs that are in front of
> CPU_REGS:RESET.
>
> I would still keep DEVCPU_GCB:CHIP_REGS as a syscon, especially since
> you are mapping the whole set of registers.
Ok. I will use a syscon for the General Control Block and a very small
range for the CPU Reset register, to minimize the register footprint.
>
>
> > + "#reset-cells":
> > + const: 1
> > +
> > +required:
> > + - compatible
> > + - reg
> > + - reg-names
> > + - "#reset-cells"
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > + - |
> > + reset: reset-controller@0 {
> > + compatible = "microchip,sparx5-switch-reset";
> > + #reset-cells = <1>;
> > + reg = <0x0 0xd0>,
> > + <0x11010000 0x10000>;
> > + reg-names = "cpu", "gcb";
> > + };
> > +
> > --
> > 2.30.0
> >
>
> --
> Alexandre Belloni, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com
Thanks for your comments
--
BR
Steen
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