Re: [PATCH v4 1/3] dt-bindings: soc: add bindings for Intel HPS Copy Engine

[Rob Herring <robh@kernel.org>]

On Sun, May 08, 2022 at 07:26:22AM -0700, matthew.gerlach@linux.intel.com wrote:
> From: Matthew Gerlach <matthew.gerlach@linux.intel.com>
> 
> Add device tree bindings documentation for the Intel Hard
> Processor System (HPS) Copy Engine.
> 
> Signed-off-by: Matthew Gerlach <matthew.gerlach@linux.intel.com>
> ---
> v4:
>   - move from soc to soc/intel/
> 
> v3:
>   - remove unused label
>   - move from misc to soc
>   - remove 0x from #address-cells/#size-cells values
>   - change hps_cp_eng@0 to dma-controller@0
>   - remote inaccurate 'items:' tag
> ---
>  .../soc/intel/intel,hps-copy-engine.yaml      | 51 +++++++++++++++++++
>  1 file changed, 51 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/soc/intel/intel,hps-copy-engine.yaml
> 
> diff --git a/Documentation/devicetree/bindings/soc/intel/intel,hps-copy-engine.yaml b/Documentation/devicetree/bindings/soc/intel/intel,hps-copy-engine.yaml
> new file mode 100644
> index 000000000000..8634865015cd
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/soc/intel/intel,hps-copy-engine.yaml
> @@ -0,0 +1,51 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +# Copyright (C) 2022, Intel Corporation
> +%YAML 1.2
> +---
> +$id: "http://devicetree.org/schemas/soc/intel/intel,hps-copy-engine.yaml#"
> +$schema: "http://devicetree.org/meta-schemas/core.yaml#"
> +
> +title: Intel HPS Copy Engine
> +
> +maintainers:
> +  - Matthew Gerlach <matthew.gerlach@linux.intel.com>
> +
> +description: |
> +  The Intel Hard Processor System (HPS) Copy Engine is an IP block used to copy
> +  a bootable image from host memory to HPS DDR.  Additionally, there is a
> +  register the HPS can use to indicate the state of booting the copied image as
> +  well as a keep-a-live indication to the host.
> +
> +properties:
> +  compatible:
> +    const: intel,hps-copy-engine
> +
> +  '#dma-cells':
> +    const: 1
> +
> +  reg:
> +    maxItems: 1
> +
> +required:
> +  - compatible
> +  - reg
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    bus@80000000 {
> +        compatible = "simple-bus";
> +        reg = <0x80000000 0x60000000>,
> +              <0xf9000000 0x00100000>;
> +        reg-names = "axi_h2f", "axi_h2f_lw";

A simple-bus doesn't have regs because it is simple. If you have 
registers, then you need a specific compatible. You can have 
'simple-bus' as a fallback if the bus is completely setup by firmware 
and the OS never needs to configure/manage it.

It also looks odd that ranges only has 4K of bus space and the bus 
registers are 1.5GB of space.

That's all kind of outside of the scope of this binding and you should 
just drop that part.

> +        #address-cells = <2>;
> +        #size-cells = <1>;
> +        ranges = <0x00000000 0x00000000 0xf9000000 0x00001000>;
> +
> +        dma-controller@0 {
> +            compatible = "intel,hps-copy-engine";
> +            reg = <0x00000000 0x00000000 0x00001000>;
> +            #dma-cells = <1>;
> +        };
> +    };
> -- 
> 2.25.1
> 
>