Re: [PATCH v4 6/7] dt-bindings: cache: r9a07g043f-l2-cache: Add DT binding documentation for L2 cache controller

[Lad, Prabhakar]

Hi Krzysztof,

Thank you for the review.

On Fri, Nov 25, 2022 at 8:16 AM Krzysztof Kozlowski
<krzysztof.kozlowski@xxxxxxxxxx> wrote:
>
> On 24/11/2022 18:22, Prabhakar wrote:
> > From: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
> >
> > Add DT binding documentation for L2 cache controller found on RZ/Five SoC.
> >
> > The Renesas RZ/Five microprocessor includes a RISC-V CPU Core (AX45MP
> > Single) from Andes. The AX45MP core has an L2 cache controller, this patch
> > describes the L2 cache block.
> >
> > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
> > ---
> > RFC v3 -> v4
> > * Dropped l2 cache configuration parameters
> > * s/larger/large
> > * Added minItems/maxItems for andestech,pma-regions
> > ---
> >  .../cache/andestech,ax45mp-cache.yaml         | 93 +++++++++++++++++++
> >  .../cache/andestech,ax45mp-cache.h            | 38 ++++++++
> >  2 files changed, 131 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/cache/andestech,ax45mp-cache.yaml
> >  create mode 100644 include/dt-bindings/cache/andestech,ax45mp-cache.h
> >
> > diff --git a/Documentation/devicetree/bindings/cache/andestech,ax45mp-cache.yaml b/Documentation/devicetree/bindings/cache/andestech,ax45mp-cache.yaml
> > new file mode 100644
> > index 000000000000..bf255b177d0a
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/cache/andestech,ax45mp-cache.yaml
> > @@ -0,0 +1,93 @@
> > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > +# Copyright (C) 2022 Renesas Electronics Corp.
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/cache/andestech,ax45mp-cache.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Andestech AX45MP L2 Cache Controller
> > +
> > +maintainers:
> > +  - Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
> > +
> > +description:
> > +  A level-2 cache (L2C) is used to improve the system performance by providing
> > +  a large amount of cache line entries and reasonable access delays. The L2C
> > +  is shared between cores, and a non-inclusive non-exclusive policy is used.
> > +
> > +select:
> > +  properties:
> > +    compatible:
> > +      contains:
> > +        enum:
> > +          - andestech,ax45mp-cache
> > +
> > +  required:
> > +    - compatible
> > +
> > +properties:
> > +  compatible:
> > +    items:
> > +      - const: andestech,ax45mp-cache
> > +      - const: cache
> > +
> > +  reg:
> > +    maxItems: 1
> > +
> > +  interrupts:
> > +    maxItems: 1
> > +
> > +  cache-line-size:
> > +    const: 64
> > +
> > +  cache-level:
> > +    const: 2
> > +
> > +  cache-sets:
> > +    const: 1024
> > +
> > +  cache-size:
> > +    enum: [131072, 262144, 524288, 1048576, 2097152]
> > +
> > +  cache-unified: true
> > +
> > +  next-level-cache: true
> > +
> > +  andestech,pma-regions:
> > +    $ref: /schemas/types.yaml#/definitions/uint32-matrix
> > +    minItems: 1
> > +    maxItems: 16
> > +    items:
> > +      minItems: 3
> > +      maxItems: 3
>
> Instead:
> items:
>   items:
>     - description: Explain
>     - description: what is
>     - description: here
>
Ok, I will do that in the next version.

- description: Memory region offset to be set up in the PMA
- description: Size of the PMA region
- description: Flags indicating how the region should be set up in the
PMA. (ETYP[1:0] | MTYP[5:2]) use the macros
defined in include/dt-bindings/cache/andestech,ax45mp-cache.h.

> > +    description: Optional array of memory regions to be set in the PMA.
> > +
> > +additionalProperties: false
> > +
> > +required:
> > +  - compatible
> > +  - cache-line-size
> > +  - cache-level
> > +  - cache-sets
> > +  - cache-size
> > +  - cache-unified
> > +  - interrupts
> > +  - reg
>
> Keep the same order as properties appear in the "properties:"
>
Agreed, will do.


> > +
> > +examples:
> > +  - |
> > +    #include <dt-bindings/interrupt-controller/irq.h>
> > +    #include <dt-bindings/cache/andestech,ax45mp-cache.h>
> > +
> > +    cache-controller@2010000 {
> > +        reg = <0x13400000 0x100000>;
> > +        compatible = "andestech,ax45mp-cache", "cache";
> > +        interrupts = <508 IRQ_TYPE_LEVEL_HIGH>;
> > +        cache-line-size = <64>;
> > +        cache-level = <2>;
> > +        cache-sets = <1024>;
> > +        cache-size = <262144>;
> > +        cache-unified;
> > +        andestech,pma-regions = <0x58000000 0x08000000
> > +                                 (AX45MP_PMACFG_ETYP_NAPOT | AX45MP_PMACFG_MTYP_MEM_NON_CACHE_BUF)>;
> > +    };
> > diff --git a/include/dt-bindings/cache/andestech,ax45mp-cache.h b/include/dt-bindings/cache/andestech,ax45mp-cache.h
> > new file mode 100644
> > index 000000000000..aa1cad24075d
> > --- /dev/null
> > +++ b/include/dt-bindings/cache/andestech,ax45mp-cache.h
> > @@ -0,0 +1,38 @@
> > +/* SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) */
> > +/*
> > + * This header provides constants for Andes AX45MP PMA configuration
> > + *
> > + * Copyright (C) 2022 Renesas Electronics Corp.
> > + */
> > +
> > +#ifndef __DT_BINDINGS_ANDESTECH_AX45MP_CACHE_H
> > +#define __DT_BINDINGS_ANDESTECH_AX45MP_CACHE_H
> > +
> > +/* OFF: PMA entry is disabled */
> > +#define AX45MP_PMACFG_ETYP_DISABLED                  0
> > +/* Naturally aligned power of 2 region */
> > +#define AX45MP_PMACFG_ETYP_NAPOT                     3
> > +
> > +/* Device, Non-bufferable */
> > +#define AX45MP_PMACFG_MTYP_DEV_NON_BUF                       (0 << 2)
> > +/* Device, bufferable */
> > +#define AX45MP_PMACFG_MTYP_DEV_BUF                   (1 << 2)
> > +/* Memory, Non-cacheable, Non-bufferable */
> > +#define AX45MP_PMACFG_MTYP_MEM_NON_CACHE_NON_BUF     (2 << 2)
> > +/* Memory, Non-cacheable, Bufferable */
> > +#define AX45MP_PMACFG_MTYP_MEM_NON_CACHE_BUF         (3 << 2)
>
> What are all these? They don't look like flags, because 3 = 1 | 2...
> they don't look like constants, because we do not use shifts in
> constants. Are these some register values? I also do not see the header
> being used in the code, so why having a bindings header if it is not
> used (DTS is not usage...)?
>
These are register bit values for the MTYP[5:2] field. The DTS example
in the binding doc (above) uses these macros. I haven't included the
DTS/I patches with this patchset yet do think I should?

Cheers,
Prabhakar