Re: [PATCH v2 1/4] dt-bindings: nvmem: Add bootcount-nvmem

Rob Herring
2021-04-29T20:53:15Z

On Wed, Apr 28, 2021 at 04:50:38PM +0300, Nandor Han wrote:
> Documents the device tree bindings for `bootcount-nvmem` driver.
>
> Signed-off-by: Nandor Han <nandor.han@vaisala.com>
> ---
> .../bindings/nvmem/bootcount-nvmem.yaml | 66 +++++++++++++++++++
> 1 file changed, 66 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/nvmem/bootcount-nvmem.yaml
>
> diff --git a/Documentation/devicetree/bindings/nvmem/bootcount-nvmem.yaml b/Documentation/devicetree/bindings/nvmem/bootcount-nvmem.yaml
> new file mode 100644
> index 000000000000..cc673452fe0f
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/nvmem/bootcount-nvmem.yaml
> @@ -0,0 +1,66 @@
> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> +# Copyright (c) Vaisala Oyj. All rights reserved.
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/nvmem/bootcount-nvmem.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Bootcount NVMEM bindings
> +
> +maintainers:
> + - Nandor Han <nandor.han@vaisala.com>
> +
> +description: |
> + This binding is intendent to describe the hardware location for
> + storing the bootcount value and magic combo.
> +
> + The NVMEM cell size should be 2 or 4 bytes.
> +
> +allOf:
> + - $ref: "nvmem-consumer.yaml#"
> +
> +properties:
> + compatible:
> + enum:
> + - linux,bootcount-nvmem

What makes this Linux specific? IIRC, u-boot has boot counting function
too.

> +
> + nvmem-cells:
> + description: Phandle to reboot mode nvmem data cell.
> + $ref: /schemas/types.yaml#/definitions/phandle-array
> +
> + nvmem-cell-names:
> + description: Name of the NVMEM cell.
> + $ref: /schemas/types.yaml#/definitions/string-array
> + enum:
> + - bootcount-regs
> +
> + linux,bootcount-magic:
> + description: Override default mask value.
> + $ref: /schemas/types.yaml#/definitions/uint32

I don't understand what this is. Is it magic or a mask?

> +
> +dependencies:
> + nvmem-cell-names: [ nvmem-cells ]

Core schema takes care of this.

> +
> +required:
> + - compatible
> + - nvmem-cells
> + - nvmem-cell-names
> +
> +additionalProperties: false
> +
> +examples:
> + # example with 16 bit nvram cell:
> + - |
> + bootcount {
> + compatible = "linux,bootcount-nvmem";
> + nvmem-cells = <&bootcount_regs>;
> + nvmem-cell-names = "bootcount-regs";
> + };
> +
> + rtc: rtc@68 {
> + bootcount_regs: bootcount_nvmem_regs@e {
> + reg = <0x0e 0x2>;

It would be simpler to just add a compatible here and get rid of the
'bootcount' node here.

> + };
> + };
> +
> +...
> --
> 2.26.3
>