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net: add helper to generate random mac address 

Add new function eth_random_enetaddr() to generate a locally administered
ethernet address.

Signed-off-by: Michael Walle <michael@walle.cc>
Acked-by: Joe Hershberger <joe.hershberger@gmail.com>
This commit is contained in:
Michael Walle 2012-06-05 11:33:16 +00:00 committed by Albert ARIBAUD
parent 99e139d590
commit 03c1b04f86
2 changed files with 39 additions and 0 deletions
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17
include/net.h
View File

@ -122,6 +122,23 @@ extern int eth_setenv_enetaddr(char *name, const uchar *enetaddr);
extern int eth_getenv_enetaddr_by_index(const char *base_name, int index,
uchar *enetaddr);
#ifdef CONFIG_RANDOM_MACADDR
/*
* The u-boot policy does not allow hardcoded ethernet addresses. Under the
* following circumstances a random generated address is allowed:
* - in emergency cases, where you need a working network connection to set
* the ethernet address.
* Eg. you want a rescue boot and don't have a serial port to access the
* CLI to set environment variables.
*
* In these cases, we generate a random locally administered ethernet address.
*
* Args:
* enetaddr - returns 6 byte hardware address
*/
extern void eth_random_enetaddr(uchar *enetaddr);
#endif
extern int usb_eth_initialize(bd_t *bi);
extern int eth_init(bd_t *bis); /* Initialize the device */
extern int eth_send(void *packet, int length); /* Send a packet */

22
net/eth.c
View File

@ -70,6 +70,28 @@ static int eth_mac_skip(int index)
return ((skip_state = getenv(enetvar)) != NULL);
}
#ifdef CONFIG_RANDOM_MACADDR
void eth_random_enetaddr(uchar *enetaddr)
{
uint32_t rval;
srand(get_timer(0));
rval = rand();
enetaddr[0] = rval & 0xff;
enetaddr[1] = (rval >> 8) & 0xff;
enetaddr[2] = (rval >> 16) & 0xff;
rval = rand();
enetaddr[3] = rval & 0xff;
enetaddr[4] = (rval >> 8) & 0xff;
enetaddr[5] = (rval >> 16) & 0xff;
/* make sure it's local and unicast */
enetaddr[0] = (enetaddr[0] | 0x02) & ~0x01;
}
#endif
/*
* CPU and board-specific Ethernet initializations. Aliased function
* signals caller to move on