[U-Boot] [PATCH v8 3/4] net: add helper to generate random mac address
Michael Walle
michael at walle.cc
Fri Jun 1 22:39:39 CEST 2012
Add new function eth_random_enetaddr() to generate a locally administered
ethernet address.
Signed-off-by: Michael Walle <michael at walle.cc>
Acked-by: Joe Hershberger <joe.hershberger at gmail.com>
---
include/net.h | 17 +++++++++++++++++
net/eth.c | 22 ++++++++++++++++++++++
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
--
1.7.2.5
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