OMAP: common: consolidate fake USB ethernet MAC address creation

TI platforms such as OMAP5uevm, PandaBoard, use equivalent
logic to generate fake USB MAC address from device unique DIE ID.

Consolidate this to a generic location such that other TI platforms such
as BeagleBoard-XM can also use the same.

NOTE: at this point in time, I dont yet see a need for a generic dummy
ethernet MAC address creation function, but if there is a need in the
future, this can be further abstracted out.

Signed-off-by: Nishanth Menon <nm@ti.com>
diff --git a/arch/arm/cpu/armv7/omap-common/utils.c b/arch/arm/cpu/armv7/omap-common/utils.c
index aabf2bd..1696c2d 100644
--- a/arch/arm/cpu/armv7/omap-common/utils.c
+++ b/arch/arm/cpu/armv7/omap-common/utils.c
@@ -5,6 +5,7 @@
  * SPDX-License-Identifier:	GPL-2.0+
  */
 #include <common.h>
+#include <asm/arch/sys_proto.h>
 static void do_cancel_out(u32 *num, u32 *den, u32 factor)
 {
 	while (1) {
@@ -39,3 +40,23 @@
 		*den = (*den + 1) / 2;
 	}
 }
+
+void __weak usb_fake_mac_from_die_id(u32 *id)
+{
+	uint8_t device_mac[6];
+
+	if (!getenv("usbethaddr")) {
+		/*
+		 * create a fake MAC address from the processor ID code.
+		 * first byte is 0x02 to signify locally administered.
+		 */
+		device_mac[0] = 0x02;
+		device_mac[1] = id[3] & 0xff;
+		device_mac[2] = id[2] & 0xff;
+		device_mac[3] = id[1] & 0xff;
+		device_mac[4] = id[0] & 0xff;
+		device_mac[5] = (id[0] >> 8) & 0xff;
+
+		eth_setenv_enetaddr("usbethaddr", device_mac);
+	}
+}