Re: [PATCH 1/3] dt-bindings: spi: Add VIA/WonderMedia serial flash controller

[Rob Herring <robh@kernel.org>]

On Sat, May 10, 2025 at 11:42:21PM +0400, Alexey Charkov wrote:
> Add a binding for the serial flash controller found on VIA/WonderMedia
> SoCs, which provides semi-transparent access to SPI NOR chips by
> mapping their contents to the physical CPU address space.
> 
> Signed-off-by: Alexey Charkov <alchark@gmail.com>
> ---
>  .../devicetree/bindings/spi/via,vt8500-sflash.yaml | 122 +++++++++++++++++++++
>  MAINTAINERS                                        |   1 +
>  2 files changed, 123 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/spi/via,vt8500-sflash.yaml b/Documentation/devicetree/bindings/spi/via,vt8500-sflash.yaml
> new file mode 100644
> index 0000000000000000000000000000000000000000..d2ea0dacdd56118c0cb5a1cb510ceb7591e1e5ca
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/spi/via,vt8500-sflash.yaml
> @@ -0,0 +1,122 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/spi/via,vt8500-sflash.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: VIA/WonderMedia serial flash controller
> +
> +description:
> +  This controller is used on VIA/WonderMedia SoCs such as VIA VT8500,
> +  WonderMedia WM8850 and similar. It provides a semi-transparent interface
> +  for reading and writing SPI NOR chip contents via a physical memory map,
> +  abstracting away all SPI communication, while also providing a direct
> +  mechanism for issuing "programmable commands" to the underlying SPI chip
> +
> +maintainers:
> +  - Alexey Charkov <alchark@gmail.com>
> +
> +properties:
> +  compatible:
> +    enum:
> +      - via,vt8500-sflash
> +      - wm,wm8505-sflash
> +      - wm,wm8650-sflash
> +      - wm,wm8750-sflash
> +      - wm,wm8850-sflash
> +
> +  reg:
> +    items:
> +      - description: MMIO registers region of the controller
> +      - description:
> +          Physical memory region within which the controller will map the
> +          flash contents of chip 0 for reading and writing. If the flash
> +          size is smaller than this region, it will be mapped at its end.
> +          Note that if this chip is used as the boot device (as is most
> +          often the case), the boot ROM maps it at the very end of the
> +          CPU address space (i.e. ending at 0xffffffff)

Period needed on the end.

> +      - description:
> +          Physical memory region within which the controller will map the
> +          flash contents of chip 1 for reading and writing. If the flash
> +          size is smaller than this region, it will be mapped at its end

Period needed on the end.

> +
> +  reg-names:
> +    items:
> +      - const: io
> +      - const: chip0-mmap
> +      - const: chip1-mmap
> +
> +  clocks:
> +    maxItems: 1
> +
> +  "#address-cells":
> +    const: 1
> +
> +  "#size-cells":
> +    const: 0

This follows the SPI binding, right? Drop these 2 and add a $ref to 
spi-controller.yaml.

> +
> +patternProperties:
> +  "^flash@[0-1]$":
> +    type: object
> +    additionalProperties: true
> +
> +    properties:
> +      reg:
> +        minimum: 0
> +        maximum: 1
> +
> +required:
> +  - compatible
> +  - reg
> +  - reg-names
> +  - clocks
> +
> +unevaluatedProperties: false
> +
> +examples:
> +  - |
> +    sflash: spi-nor-controller@d8002000 {

spi@...

> +        compatible = "wm,wm8850-sflash";
> +        reg = <0xd8002000 0x400>,
> +              <0xff800000 0x800000>,
> +              <0xef800000 0x800000>;
> +        reg-names = "io", "chip0-mmap", "chip1-mmap";
> +        clocks = <&clksf>;
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        flash@0 {
> +            compatible = "jedec,spi-nor";
> +            reg = <0>;
> +
> +            partitions {
> +                compatible = "fixed-partitions";
> +                #address-cells = <1>;
> +                #size-cells = <1>;
> +
> +                partition@0 {
> +                    label = "U-boot";

The somewhat standard value here is 'u-boot'.

> +                    reg = <0 0x50000>;
> +                    read-only;
> +                };
> +
> +                partition@1 {
> +                    label = "U-boot environment 1";

u-boot-env

> +                    reg = <0x50000 0x10000>;
> +                };
> +
> +                partition@2 {
> +                    label = "U-boot environment 2";

alt-u-boot-env or u-boot-env-backup?

> +                    reg = <0x60000 0x10000>;
> +                };
> +
> +                partition@3 {
> +                    label = "W-load";
> +                    reg = <0x70000 0x10000>;
> +                    read-only;
> +                };
> +            };
> +        };
> +    };
> +
> +...
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 6dbdf02d6b0c9357ad1da520a0f6c16b7f38f879..f09c457bbfc5ef71a3f8379c111bac52b767cbbc 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -3475,6 +3475,7 @@ F:	Documentation/devicetree/bindings/hwinfo/via,vt8500-scc-id.yaml
>  F:	Documentation/devicetree/bindings/i2c/wm,wm8505-i2c.yaml
>  F:	Documentation/devicetree/bindings/interrupt-controller/via,vt8500-intc.yaml
>  F:	Documentation/devicetree/bindings/pwm/via,vt8500-pwm.yaml
> +F:	Documentation/devicetree/bindings/spi/via,vt8500-sflash.yaml
>  F:	arch/arm/boot/dts/vt8500/
>  F:	arch/arm/mach-vt8500/
>  F:	drivers/clocksource/timer-vt8500.c
> 
> -- 
> 2.49.0
>