From 90ef0a7b0622c62758b2638604927867775479ea Mon Sep 17 00:00:00 2001
From: "Russell King (Oracle)" <rmk+kernel@armlinux.org.uk>
Date: Thu, 13 Jul 2023 09:42:07 +0100
Subject: [PATCH] net: phylink: add pcs_enable()/pcs_disable() methods

Add phylink PCS enable/disable callbacks that will allow us to place
IEEE 802.3 register compliant PCS in power-down mode while not being
used.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 drivers/net/phy/phylink.c | 48 +++++++++++++++++++++++++++++++--------
 include/linux/phylink.h   | 16 +++++++++++++
 2 files changed, 55 insertions(+), 9 deletions(-)

--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -34,6 +34,10 @@ enum {
 	PHYLINK_DISABLE_STOPPED,
 	PHYLINK_DISABLE_LINK,
 	PHYLINK_DISABLE_MAC_WOL,
+
+	PCS_STATE_DOWN = 0,
+	PCS_STATE_STARTING,
+	PCS_STATE_STARTED,
 };
 
 /**
@@ -72,6 +76,7 @@ struct phylink {
 	struct phylink_link_state phy_state;
 	struct work_struct resolve;
 	unsigned int pcs_neg_mode;
+	unsigned int pcs_state;
 
 	bool mac_link_dropped;
 	bool using_mac_select_pcs;
@@ -992,6 +997,22 @@ static void phylink_resolve_an_pause(str
 	}
 }
 
+static void phylink_pcs_disable(struct phylink_pcs *pcs)
+{
+	if (pcs && pcs->ops->pcs_disable)
+		pcs->ops->pcs_disable(pcs);
+}
+
+static int phylink_pcs_enable(struct phylink_pcs *pcs)
+{
+	int err = 0;
+
+	if (pcs && pcs->ops->pcs_enable)
+		err = pcs->ops->pcs_enable(pcs);
+
+	return err;
+}
+
 static int phylink_pcs_config(struct phylink_pcs *pcs, unsigned int neg_mode,
 			      const struct phylink_link_state *state,
 			      bool permit_pause_to_mac)
@@ -1094,11 +1115,17 @@ static void phylink_major_config(struct
 	/* If we have a new PCS, switch to the new PCS after preparing the MAC
 	 * for the change.
 	 */
-	if (pcs_changed)
+	if (pcs_changed) {
+		phylink_pcs_disable(pl->pcs);
+
 		pl->pcs = pcs;
+	}
 
 	phylink_mac_config(pl, state);
 
+	if (pl->pcs_state == PCS_STATE_STARTING || pcs_changed)
+		phylink_pcs_enable(pl->pcs);
+
 	neg_mode = pl->cur_link_an_mode;
 	if (pl->pcs && pl->pcs->neg_mode)
 		neg_mode = pl->pcs_neg_mode;
@@ -1586,6 +1613,7 @@ struct phylink *phylink_create(struct ph
 	pl->link_config.pause = MLO_PAUSE_AN;
 	pl->link_config.speed = SPEED_UNKNOWN;
 	pl->link_config.duplex = DUPLEX_UNKNOWN;
+	pl->pcs_state = PCS_STATE_DOWN;
 	pl->mac_ops = mac_ops;
 	__set_bit(PHYLINK_DISABLE_STOPPED, &pl->phylink_disable_state);
 	timer_setup(&pl->link_poll, phylink_fixed_poll, 0);
@@ -1987,6 +2015,8 @@ void phylink_start(struct phylink *pl)
 	if (pl->netdev)
 		netif_carrier_off(pl->netdev);
 
+	pl->pcs_state = PCS_STATE_STARTING;
+
 	/* Apply the link configuration to the MAC when starting. This allows
 	 * a fixed-link to start with the correct parameters, and also
 	 * ensures that we set the appropriate advertisement for Serdes links.
@@ -1997,6 +2027,8 @@ void phylink_start(struct phylink *pl)
 	 */
 	phylink_mac_initial_config(pl, true);
 
+	pl->pcs_state = PCS_STATE_STARTED;
+
 	phylink_enable_and_run_resolve(pl, PHYLINK_DISABLE_STOPPED);
 
 	if (pl->cfg_link_an_mode == MLO_AN_FIXED && pl->link_gpio) {
@@ -2015,15 +2047,9 @@ void phylink_start(struct phylink *pl)
 			poll = true;
 	}
 
-	switch (pl->cfg_link_an_mode) {
-	case MLO_AN_FIXED:
+	if (pl->cfg_link_an_mode == MLO_AN_FIXED)
 		poll |= pl->config->poll_fixed_state;
-		break;
-	case MLO_AN_INBAND:
-		if (pl->pcs)
-			poll |= pl->pcs->poll;
-		break;
-	}
+
 	if (poll)
 		mod_timer(&pl->link_poll, jiffies + HZ);
 	if (pl->phydev)
@@ -2060,6 +2086,10 @@ void phylink_stop(struct phylink *pl)
 	}
 
 	phylink_run_resolve_and_disable(pl, PHYLINK_DISABLE_STOPPED);
+
+	pl->pcs_state = PCS_STATE_DOWN;
+
+	phylink_pcs_disable(pl->pcs);
 }
 EXPORT_SYMBOL_GPL(phylink_stop);
 
--- a/include/linux/phylink.h
+++ b/include/linux/phylink.h
@@ -533,6 +533,8 @@ struct phylink_pcs {
 /**
  * struct phylink_pcs_ops - MAC PCS operations structure.
  * @pcs_validate: validate the link configuration.
+ * @pcs_enable: enable the PCS.
+ * @pcs_disable: disable the PCS.
  * @pcs_get_state: read the current MAC PCS link state from the hardware.
  * @pcs_config: configure the MAC PCS for the selected mode and state.
  * @pcs_an_restart: restart 802.3z BaseX autonegotiation.
@@ -542,6 +544,8 @@ struct phylink_pcs {
 struct phylink_pcs_ops {
 	int (*pcs_validate)(struct phylink_pcs *pcs, unsigned long *supported,
 			    const struct phylink_link_state *state);
+	int (*pcs_enable)(struct phylink_pcs *pcs);
+	void (*pcs_disable)(struct phylink_pcs *pcs);
 	void (*pcs_get_state)(struct phylink_pcs *pcs,
 			      struct phylink_link_state *state);
 	int (*pcs_config)(struct phylink_pcs *pcs, unsigned int neg_mode,
@@ -572,6 +576,18 @@ int pcs_validate(struct phylink_pcs *pcs
 		 const struct phylink_link_state *state);
 
 /**
+ * pcs_enable() - enable the PCS.
+ * @pcs: a pointer to a &struct phylink_pcs.
+ */
+int pcs_enable(struct phylink_pcs *pcs);
+
+/**
+ * pcs_disable() - disable the PCS.
+ * @pcs: a pointer to a &struct phylink_pcs.
+ */
+void pcs_disable(struct phylink_pcs *pcs);
+
+/**
  * pcs_get_state() - Read the current inband link state from the hardware
  * @pcs: a pointer to a &struct phylink_pcs.
  * @state: a pointer to a &struct phylink_link_state.
