[PATCH 2/8] w1: introduce helper to generate mac address from 1-wire id

[Jean-Christophe PLAGNIOL-VILLARD]

use the first 3 byte of the id of a 1-wire
or 6 if no OUI provided device to provide an Ethernet address

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj at jcrosoft.com>
---
 include/w1_mac_address.h |   72 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 72 insertions(+)
 create mode 100644 include/w1_mac_address.h

diff --git a/include/w1_mac_address.h b/include/w1_mac_address.h
new file mode 100644
index 0000000..78348be
--- /dev/null
+++ b/include/w1_mac_address.h
@@ -0,0 +1,72 @@
+/*
+ * Copyright (C) 2012 Jean-Christophe PLAGNIOL-VILLARD <plagnio at jcrosoft.com>
+ *
+ * Under GPLv2 only
+ */
+
+#ifndef __W1_MAC_ADDRESS_H__
+#define __W1_MAC_ADDRESS_H__
+
+/**
+ * w1_mac_address_register - use the first 3 byte of the id of a 1-wire
+ * or 6 if no OUI provided device to provide an Ethernet address
+ * @ethid: ethernet device id
+ * @local: generate a local Ethernet address
+ * @oui: Ethernet OUI (3 bytes
+ * @w1_dev: 1-wire device name
+ *
+ * Generate a Ethernet address (MAC) that is not multicast using a 1-wire id.
+ */
+static inline int w1_mac_address_register(int ethid, bool local,
+					 char * oui, char *w1_dev)
+{
+	char addr[6];
+	const char *val;
+	u64 id;
+	int nb_oui = 0;
+	int i, shift;
+	char *tmp = NULL;
+	int ret = 0;
+
+	if (!local && !oui)
+		return -EINVAL;
+
+	if (oui) {
+		nb_oui = 3;
+
+		for (i = 0; i < nb_oui; i++)
+			addr[i] = oui[i];
+	}
+
+	tmp = asprintf("%s.id", w1_dev);
+	if (!tmp)
+		return -ENOMEM;
+
+	val = getenv(tmp);
+	if (!val) {
+		ret = -EINVAL;
+		goto err;
+	}
+
+	id = simple_strtoull(val, NULL, 16);
+	if (!id) {
+		ret = -EINVAL;
+		goto err;
+	}
+
+	for (i = nb_oui, shift = 40; i < 6; i++, shift -= 8)
+		addr[i] = (id >> shift) & 0xff;
+
+	if (local) {
+		addr[0] &= 0xfe;	/* clear multicast bit */
+		addr[0] |= 0x02;	/* set local assignment bit (IEEE802) */
+	}
+
+	eth_register_ethaddr(ethid, addr);
+
+err:
+	free(tmp);
+	return ret;
+}
+
+#endif /* __W1_MAC_ADDRESS_H__ */
-- 
1.7.10.4