[PATCH v2 05/13] net: port nvmem_get_mac_address() from linux kernel

[Oleksij Rempel]

Port nvmem help to read mac-address from nvmem cell linked to the
ethernet node. This function was ported from kernel 5.8-rc1.

Signed-off-by: Oleksij Rempel <o.rempel at pengutronix.de>
---
 include/net.h |  4 ++++
 net/eth.c     | 38 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+)

diff --git a/include/net.h b/include/net.h
index 54db8a179a..a5bfe9e7f8 100644
--- a/include/net.h
+++ b/include/net.h
@@ -97,9 +97,13 @@ static inline void of_eth_register_ethaddr(struct device_node *node,
 		const char *ethaddr)
 {
 }
+static inline int nvmem_get_mac_address(struct device_d *dev, void *addrbuf)
+{
+}
 #else
 void eth_register_ethaddr(int ethid, const char *ethaddr);
 void of_eth_register_ethaddr(struct device_node *node, const char *ethaddr);
+int nvmem_get_mac_address(struct device_d *dev, void *addrbuf);
 #endif
 /*
  *	Ethernet header
diff --git a/net/eth.c b/net/eth.c
index e3d0d06efe..b33ef5fe1f 100644
--- a/net/eth.c
+++ b/net/eth.c
@@ -29,6 +29,7 @@
 #include <globalvar.h>
 #include <environment.h>
 #include <linux/ctype.h>
+#include <linux/nvmem-consumer.h>
 #include <linux/stat.h>
 
 static uint64_t last_link_check;
@@ -152,6 +153,43 @@ void of_eth_register_ethaddr(struct device_node *node, const char *ethaddr)
 	list_add_tail(&addr->list, &ethaddr_list);
 }
 
+/**
+ * Obtain the MAC address from an nvmem cell named 'mac-address' associated
+ * with given device.
+ *
+ * @dev:	Device with which the mac-address cell is associated.
+ * @addrbuf:	Buffer to which the MAC address will be copied on success.
+ *
+ * Returns 0 on success or a negative error number on failure.
+ */
+int nvmem_get_mac_address(struct device_d *dev, void *addrbuf)
+{
+	struct nvmem_cell *cell;
+	const void *mac;
+	size_t len;
+
+	cell = nvmem_cell_get(dev, "mac-address");
+	if (IS_ERR(cell))
+		return PTR_ERR(cell);
+
+	mac = nvmem_cell_read(cell, &len);
+	nvmem_cell_put(cell);
+
+	if (IS_ERR(mac))
+		return PTR_ERR(mac);
+
+	if (len != ETH_ALEN || !is_valid_ether_addr(mac)) {
+		kfree(mac);
+		return -EINVAL;
+	}
+
+	memcpy(addrbuf, mac, ETH_ALEN);
+	kfree(mac);
+
+	return 0;
+}
+EXPORT_SYMBOL(nvmem_get_mac_address);
+
 struct eth_device *eth_get_byname(const char *ethname)
 {
 	struct eth_device *edev;
-- 
2.28.0