net: phy: add support for Micrel's KSZ9021

Add the gigabit phy KSZ9021.
Also, add function ksz9021_phy_extended_write
/_read for access to the phys extended registers.
The environment variable "disable_giga"
can be used to disable 1000baseTx.

Signed-off-by: Troy Kisky <troy.kisky@boundarydevices.com>
Acked-by: Dirk Behme <dirk.behme@de.bosch.com>
diff --git a/include/micrel.h b/include/micrel.h
new file mode 100644
index 0000000..25e8a46
--- /dev/null
+++ b/include/micrel.h
@@ -0,0 +1,16 @@
+#ifndef _MICREL_H
+
+#define MII_KSZ9021_EXT_COMMON_CTRL		0x100
+#define MII_KSZ9021_EXT_STRAP_STATUS		0x101
+#define MII_KSZ9021_EXT_OP_STRAP_OVERRIDE	0x102
+#define MII_KSZ9021_EXT_OP_STRAP_STATUS		0x103
+#define MII_KSZ9021_EXT_RGMII_CLOCK_SKEW	0x104
+#define MII_KSZ9021_EXT_RGMII_RX_DATA_SKEW	0x105
+#define MII_KSZ9021_EXT_RGMII_TX_DATA_SKEW	0x106
+#define MII_KSZ9021_EXT_ANALOG_TEST		0x107
+
+struct phy_device;
+int ksz9021_phy_extended_write(struct phy_device *phydev, int regnum, u16 val);
+int ksz9021_phy_extended_read(struct phy_device *phydev, int regnum);
+
+#endif