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authorMichael Walle <michael@walle.cc>2012-06-05 11:33:16 +0000
committerAlbert ARIBAUD <albert.u.boot@aribaud.net>2012-07-07 14:07:32 +0200
commit03c1b04f86ddd6a296e2d80d73f5e4670e55da1d (patch)
treeb4d8209cc1b1dee7b0ced4ab179c09b01cc5ab52
parent99e139d5902e488eb779cd4f00c978f3803c39be (diff)
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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>
-rw-r--r--include/net.h17
-rw-r--r--net/eth.c22
2 files changed, 39 insertions, 0 deletions
diff --git a/include/net.h b/include/net.h
index a092f29..6d2d6cd 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 d9a6430..d526264 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