net: Refactor full duplex flow control resolution

These 4 drivers have identical full duplex flow control resolution
functions.  This patch changes them all to use one common function.

The function in question decides whether a device should enable TX and
RX flow control in a standard way (IEEE 802.3-2005 table 28B-3), so this
should also be useful for other drivers.

Signed-off-by: Steve Glendinning <steve.glendinning@smsc.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 29 insertions, 0 deletions

diff --git a/include/linux/mii.h b/include/linux/mii.h
index 4a376e0816fd..ad748588faf1 100644
--- a/include/linux/mii.h
+++ b/include/linux/mii.h
@@ -239,5 +239,34 @@ static inline unsigned int mii_duplex (unsigned int duplex_lock,
         return 0;
 }
 
+/**
+ * mii_resolve_flowctrl_fdx
+ * @lcladv: value of MII ADVERTISE register
+ * @rmtadv: value of MII LPA register
+ *
+ * Resolve full duplex flow control as per IEEE 802.3-2005 table 28B-3
+ */
+static inline u8 mii_resolve_flowctrl_fdx(u16 lcladv, u16 rmtadv)
+{
+        u8 cap = 0;
+
+        if (lcladv & ADVERTISE_PAUSE_CAP) {
+                if (lcladv & ADVERTISE_PAUSE_ASYM) {
+                        if (rmtadv & LPA_PAUSE_CAP)
+                                cap = FLOW_CTRL_TX | FLOW_CTRL_RX;
+                        else if (rmtadv & LPA_PAUSE_ASYM)
+                                cap = FLOW_CTRL_RX;
+                } else {
+                        if (rmtadv & LPA_PAUSE_CAP)
+                                cap = FLOW_CTRL_TX | FLOW_CTRL_RX;
+                }
+        } else if (lcladv & ADVERTISE_PAUSE_ASYM) {
+                if ((rmtadv & LPA_PAUSE_CAP) && (rmtadv & LPA_PAUSE_ASYM))
+                        cap = FLOW_CTRL_TX;
+        }
+
+        return cap;
+}
+
 #endif /* __KERNEL__ */
 #endif /* __LINUX_MII_H__ */