u-boot/arch/arm/cpu/armv7/omap-common/utils.c
Nishanth Menon 8a0c6d6fa9 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>
2014-04-17 14:39:54 -04:00

62 lines
1.4 KiB
C

/*
* Copyright 2011 Linaro Limited
* Aneesh V <aneesh@ti.com>
*
* 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) {
if (((*num)/factor*factor == (*num)) &&
((*den)/factor*factor == (*den))) {
(*num) /= factor;
(*den) /= factor;
} else
break;
}
}
/*
* Cancel out the denominator and numerator of a fraction
* to get smaller numerator and denominator.
*/
void cancel_out(u32 *num, u32 *den, u32 den_limit)
{
do_cancel_out(num, den, 2);
do_cancel_out(num, den, 3);
do_cancel_out(num, den, 5);
do_cancel_out(num, den, 7);
do_cancel_out(num, den, 11);
do_cancel_out(num, den, 13);
do_cancel_out(num, den, 17);
while ((*den) > den_limit) {
*num /= 2;
/*
* Round up the denominator so that the final fraction
* (num/den) is always <= the desired value
*/
*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);
}
}