[RFC PATCH 1/3] of: provide a binding for the 'fixed-link' property

[Thomas Petazzoni]

Some Ethernet MACs have a "fixed link", and are not connected to a
normal MDIO-managed PHY device. For those situations, a Device Tree
binding allows to describe a "fixed link", as a "fixed-link" property
of the Ethernet device Device Tree node.

This patch adds:

 * A documentation for the Device Tree property "fixed-link".

 * A of_phy_register_fixed_link() OF helper, which provided an OF node
   that contains a "fixed-link" property, registers the corresponding
   fixed PHY.

 * Removes the warning on the of_phy_connect_fixed_link() that says
   new drivers should not use it, since Grant Likely indicated that
   this "fixed-link" property is indeed the way to go.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
---
 .../devicetree/bindings/net/fixed-link.txt         | 26 ++++++++++++++++
 drivers/of/of_mdio.c                               | 36 +++++++++++++++++++---
 include/linux/of_mdio.h                            | 10 ++++++
 3 files changed, 68 insertions(+), 4 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/net/fixed-link.txt

diff --git a/Documentation/devicetree/bindings/net/fixed-link.txt b/Documentation/devicetree/bindings/net/fixed-link.txt
new file mode 100644
index 0000000..25a009a
--- /dev/null
+++ b/Documentation/devicetree/bindings/net/fixed-link.txt
@@ -0,0 +1,26 @@
+Fixed link Device Tree binding
+------------------------------
+
+Some Ethernet MACs have a "fixed link", and are not connected to a
+normal MDIO-managed PHY device. For those situations, a Device Tree
+binding allows to describe a "fixed link".
+
+Such a fixed link situation is described within an Ethernet device
+Device Tree node using a 'fixed-link' property, composed of 5
+elements:
+
+ 1. A fake PHY ID, which must be unique accross all fixed-link PHYs in
+    the system.
+ 2. The duplex (1 for full-duplex, 0 for half-duplex)
+ 3. The speed (10, 100, 1000)
+ 4. The pause setting (1 for enabled, 0 for disabled)
+ 5. The asym pause setting (1 for enabled, 0 for disabled)
+
+Example:
+
+ethernet at 0 {
+	...
+	fixed-link = <1 1 1000 0 0>;
+	...
+};
+
diff --git a/drivers/of/of_mdio.c b/drivers/of/of_mdio.c
index d5a57a9..66d5591 100644
--- a/drivers/of/of_mdio.c
+++ b/drivers/of/of_mdio.c
@@ -14,6 +14,7 @@
 #include <linux/netdevice.h>
 #include <linux/err.h>
 #include <linux/phy.h>
+#include <linux/phy_fixed.h>
 #include <linux/of.h>
 #include <linux/of_irq.h>
 #include <linux/of_mdio.h>
@@ -215,10 +216,6 @@ EXPORT_SYMBOL(of_phy_connect);
  * @dev: pointer to net_device claiming the phy
  * @hndlr: Link state callback for the network device
  * @iface: PHY data interface type
- *
- * This function is a temporary stop-gap and will be removed soon.  It is
- * only to support the fs_enet, ucc_geth and gianfar Ethernet drivers.  Do
- * not call this function from new drivers.
  */
 struct phy_device *of_phy_connect_fixed_link(struct net_device *dev,
 					     void (*hndlr)(struct net_device *),
@@ -247,3 +244,34 @@ struct phy_device *of_phy_connect_fixed_link(struct net_device *dev,
 	return IS_ERR(phy) ? NULL : phy;
 }
 EXPORT_SYMBOL(of_phy_connect_fixed_link);
+
+#if defined(CONFIG_FIXED_PHY)
+/**
+ * of_phy_register_fixed_link - Parse fixed-link property and register a dummy phy
+ * @np: pointer to the OF device node that contains the "fixed-link"
+ * property for which a dummy phy should be registered.
+ */
+#define FIXED_LINK_PROPERTIES_COUNT 5
+int of_phy_register_fixed_link(struct device_node *np)
+{
+	struct fixed_phy_status status = {};
+	u32 fixed_link_props[FIXED_LINK_PROPERTIES_COUNT];
+	int ret;
+
+	ret = of_property_read_u32_array(np, "fixed-link",
+					 fixed_link_props,
+					 FIXED_LINK_PROPERTIES_COUNT);
+	if (ret < 0)
+		return ret;
+
+	status.link       = 1;
+	status.duplex     = fixed_link_props[1];
+	status.speed      = fixed_link_props[2];
+	status.pause      = fixed_link_props[3];
+	status.asym_pause = fixed_link_props[4];
+
+	return fixed_phy_add(PHY_POLL, fixed_link_props[0],
+			     &status);
+}
+EXPORT_SYMBOL(of_phy_register_fixed_link);
+#endif
diff --git a/include/linux/of_mdio.h b/include/linux/of_mdio.h
index 8163107..bf6efea 100644
--- a/include/linux/of_mdio.h
+++ b/include/linux/of_mdio.h
@@ -57,4 +57,14 @@ static inline struct mii_bus *of_mdio_find_bus(struct device_node *mdio_np)
 }
 #endif /* CONFIG_OF */
 
+#if defined(CONFIG_OF) && defined(CONFIG_FIXED_PHY)
+extern int of_phy_register_fixed_link(struct device_node *np);
+#else
+static inline int of_phy_register_fixed_link(struct device_node *np)
+{
+	return -ENOSYS;
+}
+#endif
+
+
 #endif /* __LINUX_OF_MDIO_H */
-- 
1.8.1.2