device property: move mac addr helpers to eth.c

Move the mac address helpers out, eth.c already contains
a bunch of similar helpers.

Suggested-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 63 insertions, 0 deletions

diff --git a/net/ethernet/eth.c b/net/ethernet/eth.c
index b57530c231a6..9ea45aae04ee 100644
--- a/net/ethernet/eth.c
+++ b/net/ethernet/eth.c
@@ -51,6 +51,7 @@
 #include <linux/if_ether.h>
 #include <linux/of_net.h>
 #include <linux/pci.h>
+#include <linux/property.h>
 #include <net/dst.h>
 #include <net/arp.h>
 #include <net/sock.h>
@@ -558,3 +559,65 @@ int nvmem_get_mac_address(struct device *dev, void *addrbuf)
 	return 0;
 }
 EXPORT_SYMBOL(nvmem_get_mac_address);
+
+static void *fwnode_get_mac_addr(struct fwnode_handle *fwnode,
+				 const char *name, char *addr,
+				 int alen)
+{
+	int ret = fwnode_property_read_u8_array(fwnode, name, addr, alen);
+
+	if (ret == 0 && alen == ETH_ALEN && is_valid_ether_addr(addr))
+		return addr;
+	return NULL;
+}
+
+/**
+ * fwnode_get_mac_address - Get the MAC from the firmware node
+ * @fwnode:	Pointer to the firmware node
+ * @addr:	Address of buffer to store the MAC in
+ * @alen:	Length of the buffer pointed to by addr, should be ETH_ALEN
+ *
+ * Search the firmware node 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 firmware tables, but were not updated by the firmware.  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.
+ */
+void *fwnode_get_mac_address(struct fwnode_handle *fwnode, char *addr, int alen)
+{
+	char *res;
+
+	res = fwnode_get_mac_addr(fwnode, "mac-address", addr, alen);
+	if (res)
+		return res;
+
+	res = fwnode_get_mac_addr(fwnode, "local-mac-address", addr, alen);
+	if (res)
+		return res;
+
+	return fwnode_get_mac_addr(fwnode, "address", addr, alen);
+}
+EXPORT_SYMBOL(fwnode_get_mac_address);
+
+/**
+ * device_get_mac_address - Get the MAC for a given device
+ * @dev:	Pointer to the device
+ * @addr:	Address of buffer to store the MAC in
+ * @alen:	Length of the buffer pointed to by addr, should be ETH_ALEN
+ */
+void *device_get_mac_address(struct device *dev, char *addr, int alen)
+{
+	return fwnode_get_mac_address(dev_fwnode(dev), addr, alen);
+}
+EXPORT_SYMBOL(device_get_mac_address);