of_net: Implement of_get_nvmem_mac_address helper

It's common practice to store MAC addresses for network interfaces into
nvmem devices. However the code to actually do this in the kernel lacks,
so this patch adds of_get_nvmem_mac_address() for drivers to obtain the
address from an nvmem cell provider.

This is particulary useful on devices where the ethernet interface cannot
be configured by the bootloader, for example because it's in an FPGA.

Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/Documentation/devicetree/bindings/net/ethernet.txt b/Documentation/devicetree/bindings/net/ethernet.txt
index 2974e63ba311aa4d053ee32cd63baea3c415d756..cfc376bc977aa0a25e64d4e1ef617a1a326fe634 100644 (file)
--- a/Documentation/devicetree/bindings/net/ethernet.txt
+++ b/Documentation/devicetree/bindings/net/ethernet.txt
@@ -10,6 +10,8 @@ Documentation/devicetree/bindings/phy/phy-bindings.txt.
   the boot program; should be used in cases where the MAC address assigned to
   the device by the boot program is different from the "local-mac-address"
   property;
+- nvmem-cells: phandle, reference to an nvmem node for the MAC address;
+- nvmem-cell-names: string, should be "mac-address" if nvmem is to be used;
 - max-speed: number, specifies maximum speed in Mbit/s supported by the device;
 - max-frame-size: number, maximum transfer unit (IEEE defined MTU), rather than
   the maximum frame size (there's contradiction in the Devicetree

diff --git a/drivers/of/of_net.c b/drivers/of/of_net.c
index d820f3edd4311821696e6045d843024166b83dfc..53189d4022a6b73fc28160cbeef4ff6fb0df15dc 100644 (file)
--- a/drivers/of/of_net.c
+++ b/drivers/of/of_net.c
@@ -7,6 +7,7 @@
  */
 #include <linux/etherdevice.h>
 #include <linux/kernel.h>
+#include <linux/nvmem-consumer.h>
 #include <linux/of_net.h>
 #include <linux/phy.h>
 #include <linux/export.h>
@@ -80,3 +81,42 @@ const void *of_get_mac_address(struct device_node *np)
        return of_get_mac_addr(np, "address");
 }
 EXPORT_SYMBOL(of_get_mac_address);
+
+/**
+ * Obtain the MAC address from an nvmem provider named 'mac-address' through
+ * device tree.
+ * On success, copies the new address into memory pointed to by addr and
+ * returns 0. Returns a negative error code otherwise.
+ * @np:                Device tree node containing the nvmem-cells phandle
+ * @addr:      Pointer to receive the MAC address using ether_addr_copy()
+ */
+int of_get_nvmem_mac_address(struct device_node *np, void *addr)
+{
+       struct nvmem_cell *cell;
+       const void *mac;
+       size_t len;
+       int ret;
+
+       cell = of_nvmem_cell_get(np, "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)) {
+               ret = -EINVAL;
+       } else {
+               ether_addr_copy(addr, mac);
+               ret = 0;
+       }
+
+       kfree(mac);
+
+       return ret;
+}
+EXPORT_SYMBOL(of_get_nvmem_mac_address);

diff --git a/include/linux/of_net.h b/include/linux/of_net.h
index 9cd72aab76fe27af17105ba93b17584c773c842f..90d81ee9e6a04112168a12723e43b95c59b190f1 100644 (file)
--- a/include/linux/of_net.h
+++ b/include/linux/of_net.h
@@ -13,6 +13,7 @@
 struct net_device;
 extern int of_get_phy_mode(struct device_node *np);
 extern const void *of_get_mac_address(struct device_node *np);
+extern int of_get_nvmem_mac_address(struct device_node *np, void *addr);
 extern struct net_device *of_find_net_device_by_node(struct device_node *np);
 #else
 static inline int of_get_phy_mode(struct device_node *np)
@@ -25,6 +26,11 @@ static inline const void *of_get_mac_address(struct device_node *np)
        return NULL;
 }
 
+static inline int of_get_nvmem_mac_address(struct device_node *np, void *addr)
+{
+       return -ENODEV;
+}
+
 static inline struct net_device *of_find_net_device_by_node(struct device_node *np)
 {
        return NULL;