Re: [PATCH 1/1] dt-bindings: reg-io-width for SiFive CLINT

[Heinrich Schuchardt]

On 10/15/21 12:14, Bin Meng wrote:
> On Fri, Oct 15, 2021 at 6:09 PM Heinrich Schuchardt
> <heinrich.schuchardt@xxxxxxxxxxxxx> wrote:
> > The CLINT in the T-HEAD 9xx processors do not support 64bit mmio access to
> > the MTIMER device. The current schema does not allow to specify this.
> >
> > OpenSBI currently uses a property 'clint,has-no-64bit-mmio' to indicate the
> > restriction. Samuael Holland suggested in
> > lib: utils/timer: Use standard property to specify 32-bit I/O
> > https://github.com/smaeul/opensbi/commit/b95e9cf7cf93b0af16fc89204378bc59ff30008e
> > to use "reg-io-width = <4>;" as the reg-io-width property is generally used
> > in the devicetree schema for such a condition.
> >
> > A release candidate of the ACLINT specification is available at
> > https://github.com/riscv/riscv-aclint/releases
> >
> > Add reg-io-width as optional property to the SiFive Core Local Interruptor.
> >
> > Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@xxxxxxxxxxxxx>
> > ---
> >   Documentation/devicetree/bindings/timer/sifive,clint.yaml | 7 +++++++
> >   1 file changed, 7 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/timer/sifive,clint.yaml b/Documentation/devicetree/bindings/timer/sifive,clint.yaml
> > index a35952f48742..266012d887b5 100644
> > --- a/Documentation/devicetree/bindings/timer/sifive,clint.yaml
> > +++ b/Documentation/devicetree/bindings/timer/sifive,clint.yaml
> > @@ -41,6 +41,13 @@ properties:
> >     reg:
> >       maxItems: 1
> >
> > +  reg-io-width:
> > +    description: |
> > +      Some CLINT implementations, e.g. on the T-HEAD 9xx, only support
> > +      32bit access for MTIMER.
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    const: 4
>
> But this is not a "sifive,clint" anyway. Should there be a new
> dt-bindings for T-Head clint variant?

I assume by new dt-bindings variant you mean: Add a new compatible 
string in Documentation/devicetree/bindings/timer/sifive,clint.yaml.

The vendor Debian image uses:
compatible = "{allwinner,sun20i-d1-clint", "sifive,clint0"};

We could add this diff in a future version of the patch:

--- a/Documentation/devicetree/bindings/timer/sifive,clint.yaml
+++ b/Documentation/devicetree/bindings/timer/sifive,clint.yaml
@@ -26,6 +26,7 @@ properties:
       - enum:
           - sifive,fu540-c000-clint
           - canaan,k210-clint
+          - allwinner,sun20i-d1-clint
       - const: sifive,clint0

     description:
@@ -33,10 +34,10 @@ properties:
       Supported compatible strings are -
       "sifive,fu540-c000-clint" for the SiFive CLINT v0 as integrated
       onto the SiFive FU540 chip, "canaan,k210-clint" for the SiFive
-      CLINT v0 as integrated onto the Canaan Kendryte K210 chip, and
+      CLINT v0 as integrated onto the Canaan Kendryte K210 chip,
       "sifive,clint0" for the SiFive CLINT v0 IP block with no chip
-      integration tweaks.
-      Please refer to sifive-blocks-ip-versioning.txt for details
+      integration tweaks, and "allwinner,sun20i-d1-clint" for the Allwinner
+      D1. Please refer to sifive-blocks-ip-versioning.txt for details

   reg:
     maxItems: 1

Best regards

Heinrich

> > +
> >     interrupts-extended:
> >       minItems: 1
>
> Regards,
> Bin