openwrt/target/linux/generic/pending-5.15/683-of_net-add-mac-address-to-of-tree.patch

From 8585756342caa6d27008d1ad0c18023e4211a40a Mon Sep 17 00:00:00 2001
From: OpenWrt community <[email protected]>
Date: Wed, 13 Jul 2022 12:22:48 +0200
Subject: [PATCH] of/of_net: write back netdev MAC-address to device-tree

The label-mac logic relies on the mac-address property of a netdev
devices of-node. However, the mac address can also be stored as a
different property or read from e.g. an mtd device.

Create this node when reading a mac-address from OF if it does not
already exist and copy the mac-address used for the device to this
property. This way, the MAC address can be accessed using procfs.

---
 net/core/of_net.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

--- a/net/core/of_net.c
+++ b/net/core/of_net.c
@@ -95,6 +95,27 @@ static int of_get_mac_addr_nvmem(struct
 	return 0;
 }
 
+static int of_add_mac_address(struct device_node *np, u8* addr)
+{
+	struct property *prop;
+
+	prop = kzalloc(sizeof(*prop), GFP_KERNEL);
+	if (!prop)
+		return -ENOMEM;
+
+	prop->name = "mac-address";
+	prop->length = ETH_ALEN;
+	prop->value = kmemdup(addr, ETH_ALEN, GFP_KERNEL);
+	if (!prop->value || of_update_property(np, prop))
+		goto free;
+
+	return 0;
+free:
+	kfree(prop->value);
+	kfree(prop);
+	return -ENOMEM;
+}
+
 /**
  * of_get_mac_address()
  * @np:		Caller's Device Node
@@ -130,17 +151,23 @@ int of_get_mac_address(struct device_nod
 
 	ret = of_get_mac_addr(np, "mac-address", addr);
 	if (!ret)
-		return 0;
+		goto found;
 
 	ret = of_get_mac_addr(np, "local-mac-address", addr);
 	if (!ret)
-		return 0;
+		goto found;
 
 	ret = of_get_mac_addr(np, "address", addr);
 	if (!ret)
-		return 0;
+		goto found;
 
-	return of_get_mac_addr_nvmem(np, addr);
+	ret = of_get_mac_addr_nvmem(np, addr);
+	if (ret)
+		return ret;
+
+found:
+	ret = of_add_mac_address(np, addr);
+	return ret;
 }
 EXPORT_SYMBOL(of_get_mac_address);