[PATCH net-next 2/3] net: ethernet: add property "nvmem_macaddr_swap" to swap macaddr bytes order

[Joakim Zhang]

From: Fugang Duan <fugang.d...@nxp.com>

ethernet controller driver call .of_get_mac_address() to get
the mac address from devictree tree, if these properties are
not present, then try to read from nvmem.

For example, read MAC address from nvmem:
of_get_mac_address()
        of_get_mac_addr_nvmem()
                nvmem_get_mac_address()

i.MX6x/7D/8MQ/8MM platforms ethernet MAC address read from
nvmem ocotp eFuses, but it requires to swap the six bytes
order.

The patch add optional property "nvmem_macaddr_swap" to swap
macaddr bytes order.

Signed-off-by: Fugang Duan <fugang.d...@nxp.com>
Signed-off-by: Joakim Zhang <qiangqing.zh...@nxp.com>
---
 net/ethernet/eth.c | 25 ++++++++++++++++++++-----
 1 file changed, 20 insertions(+), 5 deletions(-)

diff --git a/net/ethernet/eth.c b/net/ethernet/eth.c
index 4106373180c6..11057671a9d6 100644
--- a/net/ethernet/eth.c
+++ b/net/ethernet/eth.c
@@ -534,8 +534,10 @@ EXPORT_SYMBOL(eth_platform_get_mac_address);
 int nvmem_get_mac_address(struct device *dev, void *addrbuf)
 {
        struct nvmem_cell *cell;
-       const void *mac;
+       const unsigned char *mac;
+       unsigned char macaddr[ETH_ALEN];
        size_t len;
+       int i = 0;
 
        cell = nvmem_cell_get(dev, "mac-address");
        if (IS_ERR(cell))
@@ -547,14 +549,27 @@ int nvmem_get_mac_address(struct device *dev, void 
*addrbuf)
        if (IS_ERR(mac))
                return PTR_ERR(mac);
 
-       if (len != ETH_ALEN || !is_valid_ether_addr(mac)) {
-               kfree(mac);
-               return -EINVAL;
+       if (len != ETH_ALEN)
+               goto invalid_addr;
+
+       if (dev->of_node &&
+           of_property_read_bool(dev->of_node, "nvmem_macaddr_swap")) {
+               for (i = 0; i < ETH_ALEN; i++)
+                       macaddr[i] = mac[ETH_ALEN - i - 1];
+       } else {
+               ether_addr_copy(macaddr, mac);
        }
 
-       ether_addr_copy(addrbuf, mac);
+       if (!is_valid_ether_addr(macaddr))
+               goto invalid_addr;
+
+       ether_addr_copy(addrbuf, macaddr);
        kfree(mac);
 
        return 0;
+
+invalid_addr:
+       kfree(mac);
+       return -EINVAL;
 }
 EXPORT_SYMBOL(nvmem_get_mac_address);
-- 
2.17.1