[U-Boot] [PATCH 2/4 v3] doc: bindings: Add description for MDIO MUX dts nodes
Alexandru Marginean
alexandru.marginean at nxp.com
Tue Jun 18 14:58:35 UTC 2019
Adds a short bindings document describing the expected structure of a MDIO
MUX dts node. This is based on Linux binding and the example is in fact
copied from there.
Signed-off-by: Alex Marginean <alexm.osslist at gmail.com>
---
Changes in v2:
- no change
Changes in v3:
- no change, just fighting with the email server
doc/device-tree-bindings/net/mdio-mux.txt | 61 +++++++++++++++++++++++
1 file changed, 61 insertions(+)
create mode 100644 doc/device-tree-bindings/net/mdio-mux.txt
diff --git a/doc/device-tree-bindings/net/mdio-mux.txt b/doc/device-tree-bindings/net/mdio-mux.txt
new file mode 100644
index 0000000000..fdf817fd93
--- /dev/null
+++ b/doc/device-tree-bindings/net/mdio-mux.txt
@@ -0,0 +1,61 @@
+The expected structure of an MDIO MUX device tree node is described here. This
+is heavily based on current Linux specification.
+The MDIO buses downstream of the MUX should be described in the device tree as
+child nodes as indicated below.
+
+Required properties:
+mdio-parent-bus = a phandle to the MDIO bus used to perform actual I/O. This is
+ typically a real MDIO device, unless there are cascaded MUXes.
+#address-cells = <1>, each MDIO group is identified by one 32b value.
+#size-cells = <0>
+
+Other properties:
+The properties described here are sufficient for MDIO MUX DM class code, but
+MUX drivers may define additional properties, either required or optional.
+
+Required properties in child nodes:
+reg = value to be configured on the MUX to select the respective downstream
+ MDIO.
+
+Child nodes should normally contain PHY nodes, referenced by phandle from
+ethernet nodes of the eth interfaces using these PHYs.
+
+Example structure, extracted from Linux bindings document:
+
+ /* The parent MDIO bus. */
+ smi1: mdio at 1180000001900 {
+ compatible = "cavium,octeon-3860-mdio";
+ #address-cells = <1>;
+ #size-cells = <0>;
+ reg = <0x11800 0x00001900 0x0 0x40>;
+ };
+
+ /*
+ An NXP sn74cbtlv3253 dual 1-of-4 switch controlled by a
+ pair of GPIO lines. Child busses 2 and 3 populated with 4
+ PHYs each.
+ */
+ mdio-mux {
+ compatible = "mdio-mux-gpio";
+ gpios = <&gpio1 3 0>, <&gpio1 4 0>;
+ mdio-parent-bus = <&smi1>;
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ mdio at 2 {
+ reg = <2>;
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ phy11: ethernet-phy at 1 {
+ reg = <1>;
+ marvell,reg-init = <3 0x10 0 0x5777>,
+ <3 0x11 0 0x00aa>,
+ <3 0x12 0 0x4105>,
+ <3 0x13 0 0x0a60>;
+ interrupt-parent = <&gpio>;
+ interrupts = <10 8>; /* Pin 10, active low */
+ };
+ };
+ };
+
--
2.17.1
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