Re: [PATCH 02/10] dt-bindings: bus: add device tree bindings for RIFSC

[Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>]

On 05/07/2023 19:27, Gatien Chevallier wrote:
> Document RIFSC (RIF security controller). RIFSC is a firewall controller
> composed of different kinds of hardware resources.
> 
> Signed-off-by: Gatien Chevallier <gatien.chevallier@foss.st.com>

A nit, subject: drop second/last, redundant "device tree bindings for".
The "dt-bindings" prefix is already stating that these are bindings. 4
words of your 6 word subject is meaningless...

> ---
>  .../bindings/bus/st,stm32-rifsc.yaml          | 101 ++++++++++++++++++
>  1 file changed, 101 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/bus/st,stm32-rifsc.yaml
> 
> diff --git a/Documentation/devicetree/bindings/bus/st,stm32-rifsc.yaml b/Documentation/devicetree/bindings/bus/st,stm32-rifsc.yaml
> new file mode 100644
> index 000000000000..68d585ed369c
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/bus/st,stm32-rifsc.yaml

Filename like compatible, unless you know list of compatibles will
grow... but then add them.

> @@ -0,0 +1,101 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/bus/st,stm32-rifsc.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: STM32 Resource isolation framework security controller bindings

Drop bindings

> +
> +maintainers:
> +  - Gatien Chevallier <gatien.chevallier@foss.st.com>
> +
> +description: |
> +  Resource isolation framework (RIF) is a comprehensive set of hardware blocks
> +  designed to enforce and manage isolation of STM32 hardware resources like
> +  memory and peripherals.
> +
> +  The RIFSC (RIF security controller) is composed of three sets of registers,
> +  each managing a specific set of hardware resources:
> +    - RISC registers associated with RISUP logic (resource isolation device unit
> +      for peripherals), assign all non-RIF aware peripherals to zero, one or
> +      any security domains (secure, privilege, compartment).
> +    - RIMC registers: associated with RIMU logic (resource isolation master
> +      unit), assign all non RIF-aware bus master to one security domain by
> +      setting secure, privileged and compartment information on the system bus.
> +      Alternatively, the RISUP logic controlling the device port access to a
> +      peripheral can assign target bus attributes to this peripheral master port
> +      (supported attribute: CID).
> +    - RISC registers associated with RISAL logic (resource isolation device unit
> +      for address space - Lite version), assign address space subregions to one
> +      security domains (secure, privilege, compartment).
> +
> +properties:
> +  compatible:
> +    const: st,stm32mp25-rifsc
> +
> +  reg:
> +    maxItems: 1
> +
> +  "#address-cells":
> +    const: 1
> +
> +  "#size-cells":
> +    const: 1
> +
> +  "#feature-domain-cells":
> +    const: 1
> +
> +  ranges: true
> +
> +  feature-domain-controller: true
> +
> +patternProperties:
> +  "^.*@[0-9a-f]+$":
> +    description: Peripherals
> +    type: object
> +    properties:
> +      feature-domains:
> +        minItems: 1
> +        maxItems: 2
> +        description:
> +          The first argument must always be a phandle that references to the
> +          firewall controller of the peripheral. The second can contain the
> +          platform specific firewall ID of the peripheral.

It does not make much sense to me to have hierarchy parent-child and via
phandle at the same time. You express the similar relationship twice.

> +
> +required:
> +  - compatible
> +  - reg
> +  - "#address-cells"
> +  - "#size-cells"
> +  - feature-domain-controller
> +  - "#feature-domain-cells"
> +  - ranges
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    // In this example, the usart2 device refers to rifsc as its domain
> +    // controller.
> +    // Access rights are verified before creating devices.
> +
> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
> +
> +    rifsc: rifsc-bus@42080000 {
> +        compatible = "st,stm32mp25-rifsc";
> +        reg = <0x42080000 0x1000>;
> +        #address-cells = <1>;
> +        #size-cells = <1>;
> +        ranges;
> +        feature-domain-controller;
> +        #feature-domain-cells = <1>;
> +
> +        usart2: serial@400e0000 {
> +            compatible = "st,stm32h7-uart";
> +            reg = <0x400e0000 0x400>;
> +            interrupts = <GIC_SPI 115 IRQ_TYPE_LEVEL_HIGH>;
> +            clocks = <&ck_flexgen_08>;
> +            feature-domains = <&rifsc 32>;
> +            status = "disabled";

No status in the examples.

> +        };
> +    };

Best regards,
Krzysztof