net: add helpers for EEE configuration

Add helpers that phylib and phylink can use to manage EEE configuration
and determine whether the MAC should be permitted to use LPI based on
that configuration.
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Link: https://lore.kernel.org/r/20240302195306.3207716-2-o.rempel@pengutronix.deSigned-off-by: Jakub Kicinski <kuba@kernel.org>

include/net/eee.h

+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef _EEE_H
+#define _EEE_H
+
+#include <linux/types.h>
+
+struct eee_config {
+	u32 tx_lpi_timer;
+	bool tx_lpi_enabled;
+	bool eee_enabled;
+};
+
+static inline bool eeecfg_mac_can_tx_lpi(const struct eee_config *eeecfg)
+{
+	/* eee_enabled is the master on/off */
+	if (!eeecfg->eee_enabled || !eeecfg->tx_lpi_enabled)
+		return false;
+
+	return true;
+}
+
+static inline void eeecfg_to_eee(struct ethtool_keee *eee,
+				 const struct eee_config *eeecfg)
+{
+	eee->tx_lpi_timer = eeecfg->tx_lpi_timer;
+	eee->tx_lpi_enabled = eeecfg->tx_lpi_enabled;
+	eee->eee_enabled = eeecfg->eee_enabled;
+}
+
+static inline void eee_to_eeecfg(struct eee_config *eeecfg,
+				 const struct ethtool_keee *eee)
+{
+	eeecfg->tx_lpi_timer = eee->tx_lpi_timer;
+	eeecfg->tx_lpi_enabled = eee->tx_lpi_enabled;
+	eeecfg->eee_enabled = eee->eee_enabled;
+}
+
+#endif