[PATCH v9 4/5] dt-bindings: riscv: Add binding for CBQRI controllers

[Drew Fustini]

On Sun, Oct 04, 2026 at 12:05:31AM +0100, Conor Dooley wrote:
> On Sat, Oct 03, 2026 at 12:12:29AM -0700, Drew Fustini wrote:
> > Document the device tree binding for RISC-V CBQRI capacity and bandwidth
> > controllers. Each controller is named by a device-specific compatible
> > followed by the generic compatible. The binding also describes the
> > common riscv,cbqri-rcid and riscv,cbqri-mcid properties, and the
> > optional riscv,cbqri-cache phandle that links a capacity controller to
> > the cache whose capacity it allocates.
> > 
> > Assisted-by: LLM
> > Reviewed-by: Conor Dooley <conor.dooley at microchip.com>
> > Co-developed-by: Adrien Ricciardi <aricciardi at baylibre.com>
> > Signed-off-by: Adrien Ricciardi <aricciardi at baylibre.com>
> > Signed-off-by: Drew Fustini <fustini at kernel.org>
> > ---
> >  .../devicetree/bindings/riscv/riscv,cbqri.yaml     | 97 ++++++++++++++++++++++
> >  MAINTAINERS                                        |  1 +
> >  2 files changed, 98 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/riscv/riscv,cbqri.yaml b/Documentation/devicetree/bindings/riscv/riscv,cbqri.yaml
> > new file mode 100644
> > index 000000000000..0924758ebdde
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/riscv/riscv,cbqri.yaml
> > @@ -0,0 +1,97 @@
> > +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/riscv/riscv,cbqri.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: RISC-V Capacity and Bandwidth QoS Register Interface (CBQRI) controller
> > +
> > +description: |
> > +  The RISC-V CBQRI specification defines capacity-controller and
> > +  bandwidth-controller register blocks that allocate cache capacity and memory
> > +  bandwidth to resource-control IDs (RCIDs) and monitor usage per
> > +  monitoring-counter ID (MCID):
> > +  https://github.com/riscv-non-isa/riscv-cbqri/blob/main/riscv-cbqri.pdf
> > +
> > +  Allocation and monitoring share one register block, and a controller may
> > +  implement either or both. A driver discovers which at runtime from the
> > +  capabilities register, so the compatible names only the controller type. It
> > +  does not distinguish allocation-only, monitoring-only or combined
> > +  controllers, and no property declares monitoring support.
> > +
> > +maintainers:
> > +  - Drew Fustini <fustini at kernel.org>
> > +
> > +properties:
> > +  compatible:
> > +    oneOf:
> > +      - items:
> > +          - enum:
> > +              - tenstorrent,ascalon-shared-cache-controller
> > +          - const: riscv,cbqri-capacity-controller
> > +      - items:
> > +          - {}
> > +          - const: riscv,cbqri-bandwidth-controller
> 
> I think I lead you up the garden path here actually, it needs to be
> "- not: {}", "- {}" permits anything.

Ah, good point. I will change it to "- not: {}" in the next rev.

Thanks,
Drew
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