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

Krzysztof Kozlowski
2022-11-25T08:16:24Z

On 24/11/2022 18:22, Prabhakar wrote:
> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
>
> 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@bp.renesas.com>
> ---
> 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@bp.renesas.com>
> +
> +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

> + 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:"

> +
> +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...)?

> +/* Memory, Write-back, No-allocate */
> +#define AX45MP_PMACFG_MTYP_MEM_WB_NA (8 << 2)
> +/* Memory, Write-back, Read-allocate */
> +#define AX45MP_PMACFG_MTYP_MEM_WB_RA (9 << 2)
> +/* Memory, Write-back, Write-allocate */
> +#define AX45MP_PMACFG_MTYP_MEM_WB_WA (10 << 2)
> +/* Memory, Write-back, Read and Write-allocate */
> +#define AX45MP_PMACFG_MTYP_MEM_WB_R_WA (11 << 2)
> +
> +/* AMO instructions are supported */
> +#define AX45MP_PMACFG_NAMO_AMO_SUPPORT (0 << 6)
> +/* AMO instructions are not supported */
> +#define AX45MP_PMACFG_NAMO_AMO_NO_SUPPORT (1 << 6)
> +
> +#endif /* __DT_BINDINGS_ANDESTECH_AX45MP_CACHE_H */

Best regards,
Krzysztof