Re: [PATCH 2/7] dt-bindings: rng: add binding for Rockchip RK3588 RNG

[Conor Dooley <conor@kernel.org>]

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On Thu, Jan 30, 2025 at 05:31:16PM +0100, Nicolas Frattaroli wrote:
> The Rockchip RK3588 SoC has two hardware RNGs accessible to the
> non-secure world: an RNG in the Crypto IP, and a standalone RNG that is
> new to this SoC.
> 
> Add a binding for this new standalone RNG.
> 
> The RNG is capable of firing an interrupt when entropy is ready, but
> all known driver implementations choose to poll instead for performance
> reasons. Hence, make the interrupt optional, as it may disappear in
> future hardware revisions entirely and certainly isn't needed for the
> hardware to function.
> 
> The reset is optional as well, as the RNG functions without an explicit
> reset. Rockchip's downstream driver does not use the reset at all,
> indicating that their engineers have deemed it unnecessary.
> 
> Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
> ---
>  .../bindings/rng/rockchip,rk3588-rng.yaml          | 61 ++++++++++++++++++++++
>  MAINTAINERS                                        |  2 +
>  2 files changed, 63 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/rng/rockchip,rk3588-rng.yaml b/Documentation/devicetree/bindings/rng/rockchip,rk3588-rng.yaml
> new file mode 100644
> index 0000000000000000000000000000000000000000..dff843fa4bf9d5704bbcd106398328588d80b02d
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/rng/rockchip,rk3588-rng.yaml
> @@ -0,0 +1,61 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/rng/rockchip,rk3588-rng.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Rockchip RK3588 TRNG
> +
> +description: True Random Number Generator on Rockchip RK3588 SoC
> +
> +maintainers:
> +  - Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
> +
> +properties:
> +  compatible:
> +    enum:
> +      - rockchip,rk3588-rng
> +
> +  reg:
> +    maxItems: 1
> +
> +  clocks:
> +    items:
> +      - description: TRNG AHB clock
> +
> +  # Optional, not used by some driver implementations
> +  interrupts:
> +    maxItems: 1
> +
> +  # Optional, hardware works without explicit reset

These sorts of comments are not needed, "required" conveys this
information.

> +  resets:
> +    maxItems: 1
> +
> +required:
> +  - compatible
> +  - reg
> +  - clocks
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/clock/rockchip,rk3588-cru.h>
> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
> +    #include <dt-bindings/interrupt-controller/irq.h>
> +    #include <dt-bindings/reset/rockchip,rk3588-cru.h>
> +    bus {
> +      #address-cells = <2>;
> +      #size-cells = <2>;
> +
> +      rng@fe378000 {
> +        compatible = "rockchip,rk3588-rng";
> +        reg = <0x0 0xfe378000 0x0 0x200>;
> +        interrupts = <GIC_SPI 400 IRQ_TYPE_LEVEL_HIGH 0>;
> +        clocks = <&scmi_clk SCMI_HCLK_SECURE_NS>;
> +        resets = <&scmi_reset SCMI_SRST_H_TRNG_NS>;
> +        status = "disabled";
> +      };
> +    };
> +
> +...
> diff --git a/MAINTAINERS b/MAINTAINERS
> index bc8ce7af3303f747e0ef028e5a7b29b0bbba99f4..7daf9bfeb0cb4e9e594b809012c7aa243b0558ae 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -20420,8 +20420,10 @@ F:	include/uapi/linux/rkisp1-config.h
>  ROCKCHIP RK3568 RANDOM NUMBER GENERATOR SUPPORT
>  M:	Daniel Golle <daniel@makrotopia.org>
>  M:	Aurelien Jarno <aurelien@aurel32.net>

> +M:	Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
^^
tbh, not really sure this part of the change should be in this patch

>  S:	Maintained
>  F:	Documentation/devicetree/bindings/rng/rockchip,rk3568-rng.yaml
> +F:	Documentation/devicetree/bindings/rng/rockchip,rk3588-rng.yaml
>  F:	drivers/char/hw_random/rockchip-rng.c
>  
>  ROCKCHIP RASTER 2D GRAPHIC ACCELERATION UNIT DRIVER
> 
> -- 
> 2.48.1
> 

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