Re: [RFC PATCH v3 2/3] dt-bindings: crypto: Add Inside Secure SafeXcel EIP-93 crypto engine

[Conor Dooley <conor@kernel.org>]

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On Mon, Oct 21, 2024 at 04:56:38PM +0200, Christian Marangi wrote:
> Add bindings for the Inside Secure SafeXcel EIP-93 crypto engine.
> 
> The IP is present on Airoha SoC and on various Mediatek devices and
> other SoC under different names like mtk-eip93 or PKTE.
> 
> Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
> ---
> Changes v3:
> - Add SoC compatible with generic one
> Changes v2:
> - Change to better compatible
> - Add description for EIP93 models
> 
>  .../crypto/inside-secure,safexcel-eip93.yaml  | 63 +++++++++++++++++++
>  1 file changed, 63 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/crypto/inside-secure,safexcel-eip93.yaml
> 
> diff --git a/Documentation/devicetree/bindings/crypto/inside-secure,safexcel-eip93.yaml b/Documentation/devicetree/bindings/crypto/inside-secure,safexcel-eip93.yaml
> new file mode 100644
> index 000000000000..13341710ee31
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/crypto/inside-secure,safexcel-eip93.yaml
> @@ -0,0 +1,63 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/crypto/inside-secure,safexcel-eip93.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Inside Secure SafeXcel EIP-93 cryptographic engine
> +
> +maintainers:
> +  - Christian Marangi <ansuelsmth@gmail.com>
> +
> +description: |
> +  The Inside Secure SafeXcel EIP-93 is a cryptographic engine IP block
> +  integrated in varios devices with very different and generic name from
> +  PKTE to simply vendor+EIP93. The real IP under the hood is actually
> +  developed by Inside Secure and given to license to vendors.
> +
> +  The IP block is sold with different model based on what feature are
> +  needed and are identified with the final letter. Each letter correspond
> +  to a specific set of feature and multiple letter reflect the sum of the
> +  feature set.
> +
> +  EIP-93 models:
> +    - EIP-93i: (basic) DES/Triple DES, AES, PRNG, IPsec ESP, SRTP, SHA1
> +    - EIP-93ie: i + SHA224/256, AES-192/256
> +    - EIP-93is: i + SSL/DTLS/DTLS, MD5, ARC4
> +    - EIP-93ies: i + e + s
> +    - EIP-93iw: i + AES-XCB-MAC, AES-CCM

This implies that you should have a non-trivial set of fallbacks, with
the "i" model as the base for that. eg:

"ie", "i"
"is", "i"
"iw", "i"
"ies", "ie, "is", "i" (I dunno which would be a better order here)

> +
> +properties:
> +  compatible:
> +    items:
> +      - const: airoha,crypto-eip93
> +      - enum:
> +          - inside-secure,safexcel-eip93i
> +          - inside-secure,safexcel-eip93ie
> +          - inside-secure,safexcel-eip93is
> +          - inside-secure,safexcel-eip93ies
> +          - inside-secure,safexcel-eip93iw

I don't really get what's going on here. Why is the first compatible the
generic one? That seems suspect to me, as I doubt the crypto block on a
particular SoC varies? I'd expect to see some soc-specific compatibles
with a fallback to the inside-secure IP version that it integrates.

Cheers,
Conor.

> +
> +  reg:
> +    maxItems: 1
> +
> +  interrupts:
> +    maxItems: 1
> +
> +required:
> +  - compatible
> +  - reg
> +  - interrupts
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
> +
> +    crypto@1e004000 {
> +      compatible = "airoha,crypto-eip93", "inside-secure,safexcel-eip93ies";
> +      reg = <0x1fb70000 0x1000>;
> +
> +      interrupts = <GIC_SPI 44 IRQ_TYPE_LEVEL_HIGH>;
> +    };
> -- 
> 2.45.2
> 

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