net: phy: improve generic EEE ethtool functions

So far the two functions consider neither member eee_enabled nor
eee_active. Therefore network drivers have to do this in some kind
of glue code. I think this can be avoided.

Getting EEE parameters:
When not advertising any EEE mode, we can't consider EEE to be enabled.
Therefore interpret "EEE enabled" as "we advertise at least one EEE
mode". It's similar with "EEE active": interpret it as "EEE modes
advertised by both link partner have at least one mode in common".

Setting EEE parameters:
If eee_enabled isn't set, don't advertise any EEE mode and restart
aneg if needed to switch off EEE. If eee_enabled is set and
data->advertised is empty (e.g. because EEE was disabled), advertise
everything we support as default. This way EEE can easily switched
on/off by doing ethtool --set-eee <if> eee on/off, w/o any additional
parameters.

The changes to both functions shouldn't break any existing user.
Once the changes have been applied, at least some users can be
simplified.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/phy.c

@@ -1144,6 +1144,7 @@ int phy_ethtool_get_eee(struct phy_device *phydev, struct ethtool_eee *data)
 	if (val < 0)
 		return val;
 	data->advertised = mmd_eee_adv_to_ethtool_adv_t(val);
+	data->eee_enabled = !!data->advertised;
 
 	/* Get LP advertisement EEE */
 	val = phy_read_mmd(phydev, MDIO_MMD_AN, MDIO_AN_EEE_LPABLE);
@@ -1151,6 +1152,8 @@ int phy_ethtool_get_eee(struct phy_device *phydev, struct ethtool_eee *data)
 		return val;
 	data->lp_advertised = mmd_eee_adv_to_ethtool_adv_t(val);
 
+	data->eee_active = !!(data->advertised & data->lp_advertised);
+
 	return 0;
 }
 EXPORT_SYMBOL(phy_ethtool_get_eee);
@@ -1164,7 +1167,7 @@ EXPORT_SYMBOL(phy_ethtool_get_eee);
  */
 int phy_ethtool_set_eee(struct phy_device *phydev, struct ethtool_eee *data)
 {
-	int cap, old_adv, adv, ret;
+	int cap, old_adv, adv = 0, ret;
 
 	if (!phydev->drv)
 		return -EIO;
@@ -1178,10 +1181,12 @@ int phy_ethtool_set_eee(struct phy_device *phydev, struct ethtool_eee *data)
 	if (old_adv < 0)
 		return old_adv;
 
-	adv = ethtool_adv_to_mmd_eee_adv_t(data->advertised) & cap;
-
-	/* Mask prohibited EEE modes */
-	adv &= ~phydev->eee_broken_modes;
+	if (data->eee_enabled) {
+		adv = !data->advertised ? cap :
+		      ethtool_adv_to_mmd_eee_adv_t(data->advertised) & cap;
+		/* Mask prohibited EEE modes */
+		adv &= ~phydev->eee_broken_modes;
+	}
 
 	if (old_adv != adv) {
 		ret = phy_write_mmd(phydev, MDIO_MMD_AN, MDIO_AN_EEE_ADV, adv);