drivers/of/of_net.c

   1 /*
   2  * OF helpers for network devices.
   3  *
   4  * This file is released under the GPLv2
   5  *
   6  * Initially copied out of arch/powerpc/kernel/prom_parse.c
   7  */
   8 #include <linux/etherdevice.h>
   9 #include <linux/kernel.h>
  10 #include <linux/of_net.h>
  11
  12 /**
  13  * Search the device tree for the best MAC address to use.  'mac-address' is
  14  * checked first, because that is supposed to contain to "most recent" MAC
  15  * address. If that isn't set, then 'local-mac-address' is checked next,
  16  * because that is the default address.  If that isn't set, then the obsolete
  17  * 'address' is checked, just in case we're using an old device tree.
  18  *
  19  * Note that the 'address' property is supposed to contain a virtual address of
  20  * the register set, but some DTS files have redefined that property to be the
  21  * MAC address.
  22  *
  23  * All-zero MAC addresses are rejected, because those could be properties that
  24  * exist in the device tree, but were not set by U-Boot.  For example, the
  25  * DTS could define 'mac-address' and 'local-mac-address', with zero MAC
  26  * addresses.  Some older U-Boots only initialized 'local-mac-address'.  In
  27  * this case, the real MAC is in 'local-mac-address', and 'mac-address' exists
  28  * but is all zeros.
  29 */
  30 const void *of_get_mac_address(struct device_node *np)
  31 {
  32         struct property *pp;
  33
  34         pp = of_find_property(np, "mac-address", NULL);
  35         if (pp && (pp->length == 6) && is_valid_ether_addr(pp->value))
  36                 return pp->value;
  37
  38         pp = of_find_property(np, "local-mac-address", NULL);
  39         if (pp && (pp->length == 6) && is_valid_ether_addr(pp->value))
  40                 return pp->value;
  41
  42         pp = of_find_property(np, "address", NULL);
  43         if (pp && (pp->length == 6) && is_valid_ether_addr(pp->value))
  44                 return pp->value;
  45
  46         return NULL;
  47 }
  48 EXPORT_SYMBOL(of_get_mac_address);