of: provide a binding for fixed link PHYs

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" using a special PHY node.

This patch adds:

 * A documentation for the fixed PHY Device Tree binding.

 * An of_phy_is_fixed_link() function that an Ethernet driver can call
   on its PHY phandle to find out whether it's a fixed link PHY or
   not. It should typically be used to know if
   of_phy_register_fixed_link() should be called.

 * An of_phy_register_fixed_link() function that instantiates the
   fixed PHY into the PHY subsystem, so that when the driver calls
   of_phy_connect(), the PHY device associated to the OF node will be
   found.

These two additional functions also support the old fixed-link Device
Tree binding used on PowerPC platforms, so that ultimately, the
network device drivers for those platforms could be converted to use
of_phy_is_fixed_link() and of_phy_register_fixed_link() instead of
of_phy_connect_fixed_link(), while keeping compatibility with their
respective Device Tree bindings.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 67 insertions, 0 deletions

diff --git a/drivers/of/of_mdio.c b/drivers/of/of_mdio.c
index 9a95831bd065..1def0bb5cb37 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>
@@ -301,3 +302,69 @@ struct phy_device *of_phy_attach(struct net_device *dev,
         return phy_attach_direct(dev, phy, flags, iface) ? NULL : phy;
 }
 EXPORT_SYMBOL(of_phy_attach);
+
+#if defined(CONFIG_FIXED_PHY)
+/*
+ * of_phy_is_fixed_link() and of_phy_register_fixed_link() must
+ * support two DT bindings:
+ * - the old DT binding, where 'fixed-link' was a property with 5
+ *   cells encoding various informations about the fixed PHY
+ * - the new DT binding, where 'fixed-link' is a sub-node of the
+ *   Ethernet device.
+ */
+bool of_phy_is_fixed_link(struct device_node *np)
+{
+        struct device_node *dn;
+        int len;
+
+        /* New binding */
+        dn = of_get_child_by_name(np, "fixed-link");
+        if (dn) {
+                of_node_put(dn);
+                return true;
+        }
+
+        /* Old binding */
+        if (of_get_property(np, "fixed-link", &len) &&
+            len == (5 * sizeof(__be32)))
+                return true;
+
+        return false;
+}
+EXPORT_SYMBOL(of_phy_is_fixed_link);
+
+int of_phy_register_fixed_link(struct device_node *np)
+{
+        struct fixed_phy_status status = {};
+        struct device_node *fixed_link_node;
+        const __be32 *fixed_link_prop;
+        int len;
+
+        /* New binding */
+        fixed_link_node = of_get_child_by_name(np, "fixed-link");
+        if (fixed_link_node) {
+                status.link = 1;
+                status.duplex = of_property_read_bool(np, "full-duplex");
+                if (of_property_read_u32(fixed_link_node, "speed", &status.speed))
+                        return -EINVAL;
+                status.pause = of_property_read_bool(np, "pause");
+                status.asym_pause = of_property_read_bool(np, "asym-pause");
+                of_node_put(fixed_link_node);
+                return fixed_phy_register(PHY_POLL, &status, np);
+        }
+
+        /* Old binding */
+        fixed_link_prop = of_get_property(np, "fixed-link", &len);
+        if (fixed_link_prop && len == (5 * sizeof(__be32))) {
+                status.link = 1;
+                status.duplex = be32_to_cpu(fixed_link_prop[1]);
+                status.speed = be32_to_cpu(fixed_link_prop[2]);
+                status.pause = be32_to_cpu(fixed_link_prop[3]);
+                status.asym_pause = be32_to_cpu(fixed_link_prop[4]);
+                return fixed_phy_register(PHY_POLL, &status, np);
+        }
+
+        return -ENODEV;
+}
+EXPORT_SYMBOL(of_phy_register_fixed_link);
+#endif