net: phy: Add phy_support_eee() indicating MAC support EEE

In order for EEE to operate, both the MAC and the PHY need to support
it, similar to how pause works. With some exception - a number of PHYs
have SmartEEE or AutoGrEEEn support in order to provide some EEE-like
power savings with non-EEE capable MACs.

Copy the pause concept and add the call phy_support_eee() which the MAC
makes after connecting the PHY to indicate it supports EEE. phylib will
then advertise EEE when auto-neg is performed.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Link: https://lore.kernel.org/r/20240302195306.3207716-6-o.rempel@pengutronix.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: lunn

drivers/net/phy/phy_device.c

@@ -2910,6 +2910,34 @@ void phy_advertise_eee_all(struct phy_device *phydev)
 }
 EXPORT_SYMBOL_GPL(phy_advertise_eee_all);
 
+/**
+ * phy_support_eee - Set initial EEE policy configuration
+ * @phydev: Target phy_device struct
+ *
+ * This function configures the initial policy for Energy Efficient Ethernet
+ * (EEE) on the specified PHY device, influencing that EEE capabilities are
+ * advertised before the link is established. It should be called during PHY
+ * registration by the MAC driver and/or the PHY driver (for SmartEEE PHYs)
+ * if MAC supports LPI or PHY is capable to compensate missing LPI functionality
+ * of the MAC.
+ *
+ * The function sets default EEE policy parameters, including preparing the PHY
+ * to advertise EEE capabilities based on hardware support.
+ *
+ * It also sets the expected configuration for Low Power Idle (LPI) in the MAC
+ * driver. If the PHY framework determines that both local and remote
+ * advertisements support EEE, and the negotiated link mode is compatible with
+ * EEE, it will set enable_tx_lpi = true. The MAC driver is expected to act on
+ * this setting by enabling the LPI timer if enable_tx_lpi is set.
+ */
+void phy_support_eee(struct phy_device *phydev)
+{
+	linkmode_copy(phydev->advertising_eee, phydev->supported_eee);
+	phydev->eee_cfg.tx_lpi_enabled = true;
+	phydev->eee_cfg.eee_enabled = true;
+}
+EXPORT_SYMBOL(phy_support_eee);
+
 /**
  * phy_support_sym_pause - Enable support of symmetrical pause
  * @phydev: target phy_device struct

include/linux/phy.h

@@ -706,7 +706,7 @@ struct phy_device {
 	__ETHTOOL_DECLARE_LINK_MODE_MASK(lp_advertising);
 	/* used with phy_speed_down */
 	__ETHTOOL_DECLARE_LINK_MODE_MASK(adv_old);
-	/* used for eee validation */
+	/* used for eee validation and configuration*/
 	__ETHTOOL_DECLARE_LINK_MODE_MASK(supported_eee);
 	__ETHTOOL_DECLARE_LINK_MODE_MASK(advertising_eee);
 	bool eee_enabled;
@@ -1973,6 +1973,7 @@ void phy_advertise_supported(struct phy_device *phydev);
 void phy_advertise_eee_all(struct phy_device *phydev);
 void phy_support_sym_pause(struct phy_device *phydev);
 void phy_support_asym_pause(struct phy_device *phydev);
+void phy_support_eee(struct phy_device *phydev);
 void phy_set_sym_pause(struct phy_device *phydev, bool rx, bool tx,
 		       bool autoneg);
 void phy_set_asym_pause(struct phy_device *phydev, bool rx, bool tx);