igb: Add i2c interface to igb.

Some of our adapters have sensors on them accessible via i2c and a private
interface.  This patch implements the kernel interface for i2c to those sensors.
Subsequent patches will provide functions to export that data.

Signed-off-by: Carolyn Wyborny <carolyn.wyborny@intel.com>
Tested-by: Jeff Pieper <jeffrey.e.pieper@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
diff --git a/drivers/net/ethernet/intel/igb/e1000_regs.h b/drivers/net/ethernet/intel/igb/e1000_regs.h
index e5db485..31c3e2f 100644
--- a/drivers/net/ethernet/intel/igb/e1000_regs.h
+++ b/drivers/net/ethernet/intel/igb/e1000_regs.h
@@ -75,6 +75,14 @@
 #define E1000_FCRTL    0x02160  /* Flow Control Receive Threshold Low - RW */
 #define E1000_FCRTH    0x02168  /* Flow Control Receive Threshold High - RW */
 #define E1000_FCRTV    0x02460  /* Flow Control Refresh Timer Value - RW */
+#define E1000_I2CPARAMS        0x0102C /* SFPI2C Parameters Register - RW */
+#define E1000_I2CBB_EN      0x00000100  /* I2C - Bit Bang Enable */
+#define E1000_I2C_CLK_OUT   0x00000200  /* I2C- Clock */
+#define E1000_I2C_DATA_OUT  0x00000400  /* I2C- Data Out */
+#define E1000_I2C_DATA_OE_N 0x00000800  /* I2C- Data Output Enable */
+#define E1000_I2C_DATA_IN   0x00001000  /* I2C- Data In */
+#define E1000_I2C_CLK_OE_N  0x00002000  /* I2C- Clock Output Enable */
+#define E1000_I2C_CLK_IN    0x00004000  /* I2C- Clock In */
 
 /* IEEE 1588 TIMESYNCH */
 #define E1000_TSYNCRXCTL 0x0B620 /* Rx Time Sync Control register - RW */