diff mbox

[U-Boot,v4,2/3] net: add helper to generate random mac address

Message ID 1336671134-16342-3-git-send-email-michael@walle.cc
State Superseded
Delegated to: Prafulla Wadaskar
Headers show

Commit Message

Michael Walle May 10, 2012, 5:32 p.m. UTC 
Add new function eth_random_enetaddr() to generate a locally administered
ethernet address.

Signed-off-by: Michael Walle <michael@walle.cc>
---
 include/net.h |   15 +++++++++++++++
 net/eth.c     |   20 ++++++++++++++++++++
 2 files changed, 35 insertions(+), 0 deletions(-)

Comments

Wolfgang Denk May 11, 2012, 7:21 p.m. UTC | #1 
Dear Michael Walle,

In message <1336671134-16342-3-git-send-email-michael@walle.cc> you wrote:
> Add new function eth_random_enetaddr() to generate a locally administered
> ethernet address.
> 
> Signed-off-by: Michael Walle <michael@walle.cc>
> ---
>  include/net.h |   15 +++++++++++++++
>  net/eth.c     |   20 ++++++++++++++++++++
>  2 files changed, 35 insertions(+), 0 deletions(-)

Please make this code configurable.  I don't want to bloat code size
for all boards when only one or two will ever use this feature.

Best regards,

Wolfgang Denk
Mike Frysinger May 14, 2012, 5:43 a.m. UTC | #2 
On Friday 11 May 2012 15:21:19 Wolfgang Denk wrote:
> Michael Walle wrote:
> > Add new function eth_random_enetaddr() to generate a locally administered
> > ethernet address.
> > 
> > Signed-off-by: Michael Walle <michael@walle.cc>
> > ---
> > 
> >  include/net.h |   15 +++++++++++++++
> >  net/eth.c     |   20 ++++++++++++++++++++
> >  2 files changed, 35 insertions(+), 0 deletions(-)
> 
> Please make this code configurable.  I don't want to bloat code size
> for all boards when only one or two will ever use this feature.

it would be nice if we could standardize gc-sections across the board
-mike
diff mbox

Patch

diff --git a/include/net.h b/include/net.h
index ee11f82..0da5679 100644
--- a/include/net.h
+++ b/include/net.h
@@ -118,6 +118,21 @@  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);
 
+/*
+ * 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);
+
 extern int usb_eth_initialize(bd_t *bi);
 extern int eth_init(bd_t *bis);			/* Initialize the device */
 extern int eth_send(volatile void *packet, int length);	   /* Send a packet */
diff --git a/net/eth.c b/net/eth.c
index 3eeb908..3623825 100644
--- a/net/eth.c
+++ b/net/eth.c
@@ -70,6 +70,26 @@  static int eth_mac_skip(int index)
 	return ((skip_state = getenv(enetvar)) != NULL);
 }
 
+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;
+}
+
 /*
  * CPU and board-specific Ethernet initializations.  Aliased function
  * signals caller to move on