linux/drivers/of/of_net.c

/*
 * 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);