smsc9420: handle magic field of ethtool_eeprom

ethtool.h says the driver should set the magic field in get_eeprom and
verify it in set_eeprom.  This patch adds this functionality using an
arbitary driver-specific magic value constant (0x9420).

Signed-off-by: Steve Glendinning <steve.glendinning@smsc.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 5 insertions, 0 deletions

diff --git a/drivers/net/smsc9420.c b/drivers/net/smsc9420.c
index 83938e1953b0..4e15ae068b3f 100644
--- a/drivers/net/smsc9420.c
+++ b/drivers/net/smsc9420.c
@@ -413,6 +413,7 @@ static int smsc9420_ethtool_get_eeprom(struct net_device *dev,
         }
 
         memcpy(data, &eeprom_data[eeprom->offset], len);
+        eeprom->magic = SMSC9420_EEPROM_MAGIC;
         eeprom->len = len;
         return 0;
 }
@@ -423,6 +424,9 @@ static int smsc9420_ethtool_set_eeprom(struct net_device *dev,
         struct smsc9420_pdata *pd = netdev_priv(dev);
         int ret;
 
+        if (eeprom->magic != SMSC9420_EEPROM_MAGIC)
+                return -EINVAL;
+
         smsc9420_eeprom_enable_access(pd);
         smsc9420_eeprom_send_cmd(pd, E2P_CMD_EPC_CMD_EWEN_);
         ret = smsc9420_eeprom_write_location(pd, eeprom->offset, *data);
diff --git a/drivers/net/smsc9420.h b/drivers/net/smsc9420.h
index 69c351f93f86..e441402f77a2 100644
--- a/drivers/net/smsc9420.h
+++ b/drivers/net/smsc9420.h
@@ -44,6 +44,7 @@
 #define LAN_REGISTER_EXTENT             (0x400)
 
 #define SMSC9420_EEPROM_SIZE            ((u32)11)
+#define SMSC9420_EEPROM_MAGIC           (0x9420)
 
 #define PKT_BUF_SZ                      (VLAN_ETH_FRAME_LEN + NET_IP_ALIGN + 4)