1 files changed, 48 insertions, 0 deletions
diff --git a/drivers/of/of_net.c b/drivers/of/of_net.c
new file mode 100644
index 000000000000..86f334a2769c
--- /dev/null
+++ b/drivers/of/of_net.c
@@ -0,0 +1,48 @@
+/*
+ * OF helpers for network devices.
+ *
+ * This file is released under the GPLv2
+ *
+ * Initially copied out of arch/powerpc/kernel/prom_parse.c
+ */
+#include <linux/etherdevice.h>
+#include <linux/kernel.h>
+#include <linux/of_net.h>
+
+/**
+ * Search the device tree for the best MAC address to use.  'mac-address' is
+ * checked first, because that is supposed to contain to "most recent" MAC
+ * address. If that isn't set, then 'local-mac-address' is checked next,
+ * because that is the default address.  If that isn't set, then the obsolete
+ * 'address' is checked, just in case we're using an old device tree.
+ *
+ * Note that the 'address' property is supposed to contain a virtual address of
+ * the register set, but some DTS files have redefined that property to be the
+ * MAC address.
+ *
+ * All-zero MAC addresses are rejected, because those could be properties that
+ * exist in the device tree, but were not set by U-Boot.  For example, the
+ * DTS could define 'mac-address' and 'local-mac-address', with zero MAC
+ * addresses.  Some older U-Boots only initialized 'local-mac-address'.  In
+ * this case, the real MAC is in 'local-mac-address', and 'mac-address' exists
+ * but is all zeros.
+*/
+const void *of_get_mac_address(struct device_node *np)
+{
+	struct property *pp;
+
+	pp = of_find_property(np, "mac-address", NULL);
+	if (pp && (pp->length == 6) && is_valid_ether_addr(pp->value))
+		return pp->value;
+
+	pp = of_find_property(np, "local-mac-address", NULL);
+	if (pp && (pp->length == 6) && is_valid_ether_addr(pp->value))
+		return pp->value;
+
+	pp = of_find_property(np, "address", NULL);
+	if (pp && (pp->length == 6) && is_valid_ether_addr(pp->value))
+		return pp->value;
+
+	return NULL;
+}
+EXPORT_SYMBOL(of_get_mac_address);