2022-09-26 19:07:19

by Sean Anderson

Subject: [PATCH net-next v5 2/9] dt-bindings: net: Add Lynx PCS binding

This binding is fairly bare-bones for now, since the Lynx driver doesn't
parse any properties (or match based on the compatible). We just need it
in order to prevent the PCS nodes from having phy devices attached to
them. This is not really a problem, but it is a bit inefficient.

This binding is really for three separate PCSs (SGMII, QSGMII, and XFI).
However, the driver treats all of them the same. This works because the
SGMII and XFI devices typically use the same address, and the SerDes
driver (or RCW) muxes between them. The QSGMII PCSs have the same
register layout as the SGMII PCSs. To do things properly, we'd probably
do something like

ethernet-pcs@0 {
#pcs-cells = <1>;
compatible = "fsl,lynx-pcs";
reg = <0>, <1>, <2>, <3>;
};

but that would add complexity, and we can describe the hardware just
fine using separate PCSs for now.

Signed-off-by: Sean Anderson <[email protected]>
---

Changes in v5:
- New

.../bindings/net/pcs/fsl,lynx-pcs.yaml | 40 +++++++++++++++++++
1 file changed, 40 insertions(+)
create mode 100644 Documentation/devicetree/bindings/net/pcs/fsl,lynx-pcs.yaml

diff --git a/Documentation/devicetree/bindings/net/pcs/fsl,lynx-pcs.yaml b/Documentation/devicetree/bindings/net/pcs/fsl,lynx-pcs.yaml
new file mode 100644
index 000000000000..fbedf696c555
--- /dev/null
+++ b/Documentation/devicetree/bindings/net/pcs/fsl,lynx-pcs.yaml
@@ -0,0 +1,40 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/net/pcs/fsl,lynx-pcs.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: NXP Lynx PCS
+
+maintainers:
+ - Ioana Ciornei <[email protected]>
+
+description: |
+ NXP Lynx 10G and 28G SerDes have Ethernet PCS devices which can be used as
+ protocol controllers. They are accessible over the Ethernet interface's MDIO
+ bus.
+
+properties:
+ compatible:
+ const: fsl,lynx-pcs
+
+ reg:
+ maxItems: 1
+
+required:
+ - compatible
+ - reg
+
+additionalProperties: false
+
+examples:
+ - |
+ mdio-bus {
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ qsgmii_pcs1: ethernet-pcs@1 {
+ compatible = "fsl,lynx-pcs";
+ reg = <1>;
+ };
+ };
--
2.35.1.1320.gc452695387.dirty

2022-09-30 14:45:14

by Rob Herring (Arm)

Subject: Re: [PATCH net-next v5 2/9] dt-bindings: net: Add Lynx PCS binding

On Mon, 26 Sep 2022 15:03:14 -0400, Sean Anderson wrote:
> This binding is fairly bare-bones for now, since the Lynx driver doesn't
> parse any properties (or match based on the compatible). We just need it
> in order to prevent the PCS nodes from having phy devices attached to
> them. This is not really a problem, but it is a bit inefficient.
>
> This binding is really for three separate PCSs (SGMII, QSGMII, and XFI).
> However, the driver treats all of them the same. This works because the
> SGMII and XFI devices typically use the same address, and the SerDes
> driver (or RCW) muxes between them. The QSGMII PCSs have the same
> register layout as the SGMII PCSs. To do things properly, we'd probably
> do something like
>
> ethernet-pcs@0 {
> #pcs-cells = <1>;
> compatible = "fsl,lynx-pcs";
> reg = <0>, <1>, <2>, <3>;
> };
>
> but that would add complexity, and we can describe the hardware just
> fine using separate PCSs for now.
>
> Signed-off-by: Sean Anderson <[email protected]>
> ---
>
> Changes in v5:
> - New
>
> .../bindings/net/pcs/fsl,lynx-pcs.yaml | 40 +++++++++++++++++++
> 1 file changed, 40 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/net/pcs/fsl,lynx-pcs.yaml
>

Reviewed-by: Rob Herring <[email protected]>