681-NET-add-mtd-mac-address-support-to-of_get_mac_addres.patch

From 6f8e5369ae054ec6c9265581d5a7e39738a5cd84 Mon Sep 17 00:00:00 2001
From: Ansuel Smith <ansuelsmth@gmail.com>
Date: Tue, 30 Mar 2021 13:16:38 +0200
Subject: [PATCH 1/2] NET: add mtd-mac-address support to of_get_mac_address()

Many embedded devices have information such as mac addresses stored inside mtd
devices. This patch allows us to add a property inside a node describing a
network interface. The new property points at a mtd partition with an offset
where the mac address can be found.

Signed-off-by: John Crispin <blogic@openwrt.org>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
---
 drivers/of/of_net.c | 75 ++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 74 insertions(+), 1 deletion(-)

--- a/drivers/of/of_net.c
+++ b/drivers/of/of_net.c
@@ -12,6 +12,7 @@
 #include <linux/export.h>
 #include <linux/device.h>
 #include <linux/nvmem-consumer.h>
+#include <linux/mtd/mtd.h>
 
 /**
  * of_get_phy_mode - Get phy mode for given device_node
@@ -95,6 +96,52 @@ static int of_get_mac_addr_nvmem(struct
 	return 0;
 }
 
+static int of_get_mac_address_mtd(struct device_node *np, u8 *addr)
+{
+#ifdef CONFIG_MTD
+	struct platform_device *pdev = of_find_device_by_node(np);
+	struct device_node *mtd_np = NULL;
+	size_t retlen;
+	int size, ret;
+	struct mtd_info *mtd;
+	const char *part;
+	const __be32 *list;
+	phandle phandle;
+	u8 mac[ETH_ALEN];
+
+	list = of_get_property(np, "mtd-mac-address", &size);
+	if (!list || (size != (2 * sizeof(*list))))
+		return -ENODEV;
+
+	phandle = be32_to_cpup(list++);
+	if (phandle)
+		mtd_np = of_find_node_by_phandle(phandle);
+
+	if (!mtd_np)
+		return -ENODEV;
+
+	part = of_get_property(mtd_np, "label", NULL);
+	if (!part)
+		part = mtd_np->name;
+
+	mtd = get_mtd_device_nm(part);
+	if (IS_ERR(mtd))
+		return -ENODEV;
+
+	ret = mtd_read(mtd, be32_to_cpup(list), 6, &retlen, mac);
+	put_mtd_device(mtd);
+
+	if (!is_valid_ether_addr(mac))
+		return -EINVAL;
+
+	memcpy(addr, mac, ETH_ALEN);
+
+	return 0;
+#endif
+	return -EINVAL;
+}
+
+
 /**
  * Search the device tree for the best MAC address to use.  'mac-address' is
  * checked first, because that is supposed to contain to "most recent" MAC
@@ -115,6 +161,10 @@ static int of_get_mac_addr_nvmem(struct
  * this case, the real MAC is in 'local-mac-address', and 'mac-address' exists
  * but is all zeros.
  *
+ *
+ * If a mtd-mac-address property exists, try to fetch the MAC address from the
+ * specified mtd device.
+ *
  * Return: 0 on success and errno in case of error.
 */
 int of_get_mac_address(struct device_node *np, u8 *addr)
@@ -136,6 +186,10 @@ int of_get_mac_address(struct device_nod
 	if (!ret)
 		return 0;
 
+	ret = of_get_mac_address_mtd(np, addr);
+	if (!ret)
+		return 0;
+
 	return of_get_mac_addr_nvmem(np, addr);
 }
 EXPORT_SYMBOL(of_get_mac_address);