From 03c1b04f86ddd6a296e2d80d73f5e4670e55da1d Mon Sep 17 00:00:00 2001 From: Michael Walle Date: Tue, 5 Jun 2012 11:33:16 +0000 Subject: [PATCH] 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 Acked-by: Joe Hershberger --- include/net.h | 17 +++++++++++++++++ net/eth.c | 22 ++++++++++++++++++++++ 2 files changed, 39 insertions(+) diff --git a/include/net.h b/include/net.h index a092f291bb..6d2d6cd849 100644 --- a/include/net.h +++ b/include/net.h @@ -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 */ diff --git a/net/eth.c b/net/eth.c index d9a643073d..d526264fa6 100644 --- a/net/eth.c +++ b/net/eth.c @@ -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 -- 2.30.2