of: net: support NVMEM cells with MAC in text format

Some NVMEM devices have text based cells. In such cases MAC is stored in
a XX:XX:XX:XX:XX:XX format. Use mac_pton() to parse such data and
support those NVMEM cells. This is required to support e.g. a very
popular U-Boot and its environment variables.
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/of_net.c

@@ -61,7 +61,7 @@ static int of_get_mac_addr_nvmem(struct device_node *np, u8 *addr)
 {
 	struct platform_device *pdev = of_find_device_by_node(np);
 	struct nvmem_cell *cell;
-	const void *mac;
+	const void *buf;
 	size_t len;
 	int ret;
 
@@ -78,21 +78,32 @@ static int of_get_mac_addr_nvmem(struct device_node *np, u8 *addr)
 	if (IS_ERR(cell))
 		return PTR_ERR(cell);
 
-	mac = nvmem_cell_read(cell, &len);
+	buf = nvmem_cell_read(cell, &len);
 	nvmem_cell_put(cell);
 
-	if (IS_ERR(mac))
-		return PTR_ERR(mac);
+	if (IS_ERR(buf))
+		return PTR_ERR(buf);
 
-	if (len != ETH_ALEN || !is_valid_ether_addr(mac)) {
-		kfree(mac);
-		return -EINVAL;
-	}
+	ret = 0;
+	if (len == ETH_ALEN) {
+		if (is_valid_ether_addr(buf))
+			memcpy(addr, buf, ETH_ALEN);
+		else
+			ret = -EINVAL;
+	} else if (len == 3 * ETH_ALEN - 1) {
+		u8 mac[ETH_ALEN];
 
+		if (mac_pton(buf, mac))
 			memcpy(addr, mac, ETH_ALEN);
-	kfree(mac);
+		else
+			ret = -EINVAL;
+	} else {
+		ret = -EINVAL;
+	}
 
-	return 0;
+	kfree(buf);
+
+	return ret;
 }
 
 /**