Add OF bindings to Micrel ksz9021 PHY

Some boards require custom PHY configuration, for example due to trace length differences. Add the ability to configure these registers in order to get the PHY to function on boards that need it.

Because PHYs are auto-detected based on MDIO device IDs, allow PHY configuration to be specified in the parent Ethernet device node if no PHY device node is present.

Signed-off-by Sean Cross <[email protected]>

Documentation/devicetree/bindings/net/micrel-ksz9021.txt new file +9 -0

@@ -0,0 +1,19 @@
+Micrel KSZ9021 Gigabit Ethernet PHY
+
+Some boards require special tuning values, particularly when it comes
+to clock delays.  You can specify clock delay values by adding
+micrel-specific properties to an Ethernet OF device node.
+
+Optional properties:
+- micrel,clk-control-pad-skew : Timing offset for the MII clock line
+- micrel,rx-data-pad-skew : Timing offset for the RX MII pad

From: Sean Cross [mailto:[email protected]]
Data: Thursday, August 01, 2013 5:19 PM

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Documentation/devicetree/bindings/net/micrel-ksz9021.txt new file +18 -0

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+Micrel KSZ9021 Gigabit Ethernet PHY
+
+Some boards require special tuning values, particularly when it comes
+to clock delays. You can specify clock delay values by adding
+micrel-specific properties to an Ethernet OF device node.
+
+Optional properties:
+- micrel,clk-control-pad-skew : Timing offset for the MII clock line
+- micrel,rx-data-pad-skew : Timing offset for the RX MII pad
+- micrel,tx-data-pad-skew : Timing offset for the TX MII pad
+
+Example:
+ &enet {
+ micrel,clk-control-pad-skew = <0xf0f0>;
+ micrel,rx-data-pad-skew = <0x0000>;
+ micrel,tx-data-pad-skew = <0xffff>;
+ status = "okay";
+ };

Documentation/devicetree/bindings/net/micrel-ksz9021.txt line 19

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Documentation/devicetree/bindings/net/micrel-ksz9021.txt new file +1 -0

+

The phy binding must be the phy node, not the ethernet node. Pls refer to:
Documentation/devicetree/booting-without-of.txt Documentation/devicetree/bindings/net/phy.txt

Documentation/devicetree/bindings/net/micrel-ksz9021.txt

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Documentation/devicetree/bindings/net/micrel-ksz9021.txt new file +7 -0

+static int ksz9021_config_init(struct phy_device *phydev) {
+ struct device *dev = &phydev->dev;
+ struct device_node *of_node = dev->of_node;
+
+ if (!of_node && dev->parent->of_node)
+ of_node = dev->parent->of_node;
+

If phy binding is phy node, there only check of_node, don't re-evaluate the phy node.

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Documentation/devicetree/bindings/net/micrel-ksz9021.txt new file +5 -0

+Example:
+ &enet {
+ micrel,clk-control-pad-skew = <0xf0f0>;  micrel,rx-data-pad-skew =
+<0x0000>;  micrel,tx-data-pad-skew = <0xffff>;  status = "okay";
+};

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+

The phy binding must be the phy node, not the ethernet node. Pls refer to:
Documentation/devicetree/booting-without-of.txt Documentation/devicetree/bindings/net/phy.txt

This won't necessarily work. In my board, I don't think it's possible to manually specify the PHY, as most of the fields required by the OF PHY node don't apply to this device (at least according to phy.txt). There are no interrupts, no interrupt parent, and it's unclear what the reg or linux,phandle fields do. All of these are required fields, none of which seem to apply to this particular board. Furthermore, it doesn't seem to be possible to specify a particular PHY, such as the ksz9021.

I see the pattern of getting OF settings from a parent's node used elsewhere in the kernel. For example, in mmc_of_parse(), or more similarly in the chipidea ci_hdrc_probe() driver.