e1000: add PCI-E capability detection code

Add code to display the detected PCI-E bus width.

Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Auke Kok <auke-jan.h.kok@intel.com>
diff --git a/drivers/net/e1000/e1000_hw.h b/drivers/net/e1000/e1000_hw.h
index b9364b5..434492c 100644
--- a/drivers/net/e1000/e1000_hw.h
+++ b/drivers/net/e1000/e1000_hw.h
@@ -418,6 +418,7 @@
 void e1000_pci_clear_mwi(struct e1000_hw *hw);
 void e1000_read_pci_cfg(struct e1000_hw *hw, uint32_t reg, uint16_t * value);
 void e1000_write_pci_cfg(struct e1000_hw *hw, uint32_t reg, uint16_t * value);
+int32_t e1000_read_pcie_cap_reg(struct e1000_hw *hw, uint32_t reg, uint16_t *value);
 /* Port I/O is only supported on 82544 and newer */
 void e1000_io_write(struct e1000_hw *hw, unsigned long port, uint32_t value);
 int32_t e1000_disable_pciex_master(struct e1000_hw *hw);
@@ -2220,6 +2221,11 @@
 #define E1000_FACTPS_LAN_FUNC_SEL                   0x40000000
 #define E1000_FACTPS_PM_STATE_CHANGED               0x80000000
 
+/* PCI-Ex Config Space */
+#define PCI_EX_LINK_STATUS           0x12
+#define PCI_EX_LINK_WIDTH_MASK       0x3F0
+#define PCI_EX_LINK_WIDTH_SHIFT      4
+
 /* EEPROM Commands - Microwire */
 #define EEPROM_READ_OPCODE_MICROWIRE  0x6  /* EEPROM read opcode */
 #define EEPROM_WRITE_OPCODE_MICROWIRE 0x5  /* EEPROM write opcode */