Re: [PATCH v3 1/3] dt-bindings: net: Add T-HEAD dwmac support

[Drew Fustini <dfustini@tenstorrent.com>]

On Tue, Oct 01, 2024 at 08:58:34AM +0200, Krzysztof Kozlowski wrote:
> On Mon, Sep 30, 2024 at 11:23:24PM -0700, Drew Fustini wrote:
> > From: Jisheng Zhang <jszhang@kernel.org>
> > 
> > Add documentation to describe the DesginWare-based GMAC controllers in
> > the T-HEAD TH1520 SoC.
> > 
> > Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
> > Signed-off-by: Emil Renner Berthing <emil.renner.berthing@canonical.com>
> > [drew: rename compatible, add apb registers as second reg of gmac node]
> > Signed-off-by: Drew Fustini <dfustini@tenstorrent.com>
> > ---
> >  .../devicetree/bindings/net/snps,dwmac.yaml        |  1 +
> >  .../devicetree/bindings/net/thead,th1520-gmac.yaml | 97 ++++++++++++++++++++++
> >  MAINTAINERS                                        |  1 +
> >  3 files changed, 99 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/net/snps,dwmac.yaml b/Documentation/devicetree/bindings/net/snps,dwmac.yaml
> > index 4e2ba1bf788c..474ade185033 100644
> > --- a/Documentation/devicetree/bindings/net/snps,dwmac.yaml
> > +++ b/Documentation/devicetree/bindings/net/snps,dwmac.yaml
> > @@ -99,6 +99,7 @@ properties:
> >          - snps,dwxgmac-2.10
> >          - starfive,jh7100-dwmac
> >          - starfive,jh7110-dwmac
> > +        - thead,th1520-gmac
> >  
> >    reg:
> >      minItems: 1
> > diff --git a/Documentation/devicetree/bindings/net/thead,th1520-gmac.yaml b/Documentation/devicetree/bindings/net/thead,th1520-gmac.yaml
> > new file mode 100644
> > index 000000000000..fef1810b10c4
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/net/thead,th1520-gmac.yaml
> > @@ -0,0 +1,97 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/net/thead,th1520-gmac.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: T-HEAD TH1520 GMAC Ethernet controller
> > +
> > +maintainers:
> > +  - Drew Fustini <dfustini@tenstorrent.com>
> > +
> > +description: |
> > +  The TH1520 GMAC is described in the TH1520 Peripheral Interface User Manual
> > +  https://git.beagleboard.org/beaglev-ahead/beaglev-ahead/-/tree/main/docs
> > +
> > +  Features include
> > +    - Compliant with IEEE802.3 Specification
> > +    - IEEE 1588-2008 standard for precision networked clock synchronization
> > +    - Supports 10/100/1000Mbps data transfer rate
> > +    - Supports RGMII/MII interface
> > +    - Preamble and start of frame data (SFD) insertion in Transmit path
> > +    - Preamble and SFD deletion in the Receive path
> > +    - Automatic CRC and pad generation options for receive frames
> > +    - MDIO master interface for PHY device configuration and management
> > +
> > +  The GMAC Registers consists of two parts
> > +    - APB registers are used to configure clock frequency/clock enable/clock
> > +      direction/PHY interface type.
> > +    - AHB registers are use to configure GMAC core (DesignWare Core part).
> > +      GMAC core register consists of DMA registers and GMAC registers.
> > +
> > +select:
> > +  properties:
> > +    compatible:
> > +      contains:
> > +        enum:
> > +          - thead,th1520-gmac
> > +  required:
> > +    - compatible
> > +
> > +allOf:
> > +  - $ref: snps,dwmac.yaml#
> > +
> > +properties:
> > +  compatible:
> > +    items:
> > +      - enum:
> > +          - thead,th1520-gmac
> > +      - const: snps,dwmac-3.70a
> > +
> > +  reg:
> > +    items:
> > +      - description: DesignWare GMAC IP core registers
> > +      - description: GMAC APB registers
> > +
> > +  reg-names:
> > +    items:
> > +      - const: dwmac
> > +      - const: apb
> 
> I don't get why none of snps,dwmac properties are restricted. How many
> interrupts do you have here? How many clocks? resets?

Thanks for pointing this out. Yes, I forgot to document the clocks,
interrupts and resets.

There needs to be 2 clocks (stmmaceth and pclk). There also needs to be
2 resets: each GMAC has a reset plus a seperate reset for the GMAC AXI
interface. There is 1 interrupt (macirq) but it is optional. The BeagleV
Ahead uses it but the LicheePi 4A does not use the interrupt.

However, I'm uncertain about how to restrict the snps,dwmac properties.

I see that starfive,jh7110-dwmac.yaml has the following logic. Should I
be adding something like this to restrict the snps,dwmac properties?

---------------------------------------------------------------------
allOf:
  - $ref: snps,dwmac.yaml#

  - if:
      properties:
        compatible:
          contains:
            const: starfive,jh7100-dwmac
    then:
      properties:
        interrupts:
          minItems: 2
          maxItems: 2

        interrupt-names:
          minItems: 2
          maxItems: 2

        resets:
          maxItems: 1

        reset-names:
          const: ahb
<snip>
---------------------------------------------------------------------
> 
> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +  - clocks
> > +  - clock-names
> > +  - interrupts
> 
> Drop

Will do.

> 
> > +  - interrupt-names
> 
> Drop

Will do.

> 
> > +  - phy-mode
> > +
> > +unevaluatedProperties: false
> 
> Best regards,
> Krzysztof

Thanks for your review,
Drew