e1000: M88 PHY workaround

M88 rev 2 PHY needs a longer downshift to function properly. This adds
a much longer downshift counter for this specific device.

Signed-off-by: Jesse Brandeburg <jesse.brandeburg@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 941b47d..1908e0d3 100644
--- a/drivers/net/e1000/e1000_hw.h
+++ b/drivers/net/e1000/e1000_hw.h
@@ -2765,6 +2765,17 @@
 #define M88E1000_EPSCR_TX_CLK_25      0x0070 /* 25  MHz TX_CLK */
 #define M88E1000_EPSCR_TX_CLK_0       0x0000 /* NO  TX_CLK */
 
+/* M88EC018 Rev 2 specific DownShift settings */
+#define M88EC018_EPSCR_DOWNSHIFT_COUNTER_MASK  0x0E00
+#define M88EC018_EPSCR_DOWNSHIFT_COUNTER_1X    0x0000
+#define M88EC018_EPSCR_DOWNSHIFT_COUNTER_2X    0x0200
+#define M88EC018_EPSCR_DOWNSHIFT_COUNTER_3X    0x0400
+#define M88EC018_EPSCR_DOWNSHIFT_COUNTER_4X    0x0600
+#define M88EC018_EPSCR_DOWNSHIFT_COUNTER_5X    0x0800
+#define M88EC018_EPSCR_DOWNSHIFT_COUNTER_6X    0x0A00
+#define M88EC018_EPSCR_DOWNSHIFT_COUNTER_7X    0x0C00
+#define M88EC018_EPSCR_DOWNSHIFT_COUNTER_8X    0x0E00
+
 /* IGP01E1000 Specific Port Config Register - R/W */
 #define IGP01E1000_PSCFR_AUTO_MDIX_PAR_DETECT  0x0010
 #define IGP01E1000_PSCFR_PRE_EN                0x0020