[e1000] Use the alternate MAC in NVRAM when available

The 82571 supports an alternate MAC address location in NVRAM.
When this is set, use this for the MAC rather than the default
physical MAC address.

Ported from linux-2.6.git 93ca161027

Signed-off-by: Alex Williamson <alex.williamson@hp.com>
Tested-by: Thomas Miletich <thomas.miletich@gmail.com>
Signed-off-by: Marty Connor <mdc@etherboot.org>

src/drivers/net/e1000/e1000_hw.c

     /* Clear any pending interrupt events. */
     icr = E1000_READ_REG(hw, ICR);
 
+    if (hw->mac_type == e1000_82571 && hw->laa_is_present == TRUE) {
+        /*
+         * Hold a copy of the LAA in RAR[14] This is done so that
+         * between the time RAR[0] gets clobbered and the time it
+         * gets fixed, the actual LAA is in one of the RARs and no
+         * incoming packets directed to this port are dropped.
+         * Eventually the LAA will be in RAR[0] and RAR[14].
+         */
+        e1000_rar_set(hw, hw->mac_addr, E1000_RAR_ENTRIES - 1);
+    }
+
     /* If MWI was previously enabled, reenable it. */
     if (hw->mac_type == e1000_82542_rev2_0) {
         if (hw->pci_cmd_word & PCI_COMMAND_INVALIDATE)
 int32_t
 e1000_read_mac_addr(struct e1000_hw * hw)
 {
-    uint16_t offset;
+    uint16_t offset, mac_addr_offset = 0;
     uint16_t eeprom_data, i;
+    int32_t ret_val;
 
     DEBUGFUNC("e1000_read_mac_addr");
 
+    if (hw->mac_type == e1000_82571) {
+        /* Check for an alternate MAC address.  An alternate MAC
+         * address can be setup by pre-boot software and must be
+         * treated like a permanent address and must override the
+         * actual permanent MAC address.*/
+        ret_val = e1000_read_eeprom(hw, EEPROM_ALT_MAC_ADDR_PTR, 1,
+                                    &mac_addr_offset);
+        if (ret_val) {
+            DEBUGOUT("EEPROM Read Error\n");
+            return -E1000_ERR_EEPROM;
+        }
+        if (mac_addr_offset == 0xFFFF)
+            mac_addr_offset = 0;
+
+        if (mac_addr_offset) {
+            if (E1000_READ_REG(hw, STATUS) & E1000_STATUS_FUNC_1)
+                mac_addr_offset += NODE_ADDRESS_SIZE/sizeof(u16);
+
+                /* make sure we have a valid mac address here
+                 * before using it */
+               ret_val = e1000_read_eeprom(hw, mac_addr_offset, 1,
+                                           &eeprom_data);
+               if (ret_val) {
+                   DEBUGOUT("EEPROM Read Error\n");
+                   return -E1000_ERR_EEPROM;
+               }
+               if (eeprom_data & 0x0001)
+                   mac_addr_offset = 0;
+        }
+
+        if (mac_addr_offset)
+            hw->laa_is_present = TRUE;
+    }
+
     for (i = 0; i < NODE_ADDRESS_SIZE; i += 2) {
-        offset = i >> 1;
+        offset = mac_addr_offset + (i >> 1);
         if (e1000_read_eeprom(hw, offset, 1, &eeprom_data) < 0) {
             DEBUGOUT("EEPROM Read Error\n");
             return -E1000_ERR_EEPROM;
     case e1000_82571:
     case e1000_82576:
     case e1000_80003es2lan:
-        if (E1000_READ_REG(hw, STATUS) & E1000_STATUS_FUNC_1)
+        if (!mac_addr_offset &&
+            E1000_READ_REG(hw, STATUS) & E1000_STATUS_FUNC_1)
             hw->perm_mac_addr[5] ^= 0x01;
         break;
     }

src/drivers/net/e1000/e1000_hw.h

 #define EEPROM_INIT_CONTROL3_PORT_A   0x0024
 #define EEPROM_CFG                    0x0012
 #define EEPROM_FLASH_VERSION          0x0032
+#define EEPROM_ALT_MAC_ADDR_PTR       0x0037
 #define EEPROM_CHECKSUM_REG           0x003F
 
 #define E1000_EEPROM_CFG_DONE         0x00040000   /* MNG config cycle done */