netdev - [RFC net-next PATCH 02/13] net: phylink: Support setting PCS link change callbacks

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Message-Id: <20250403181907.1947517-3-sean.anderson@linux.dev>
Date: Thu,  3 Apr 2025 14:18:56 -0400
From: Sean Anderson <sean.anderson@...ux.dev>
To: netdev@...r.kernel.org,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S . Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Russell King <linux@...linux.org.uk>
Cc: linux-kernel@...r.kernel.org,
	Christian Marangi <ansuelsmth@...il.com>,
	upstream@...oha.com,
	Heiner Kallweit <hkallweit1@...il.com>,
	Sean Anderson <sean.anderson@...ux.dev>
Subject: [RFC net-next PATCH 02/13] net: phylink: Support setting PCS link change callbacks

Support changing the link change callback, similar to how PHYs do it.
This will allow the PCS wrapper to forward link changes to the wrapped
PCS.

Signed-off-by: Sean Anderson <sean.anderson@...ux.dev>
---

 drivers/net/phy/phylink.c | 24 +++++++-----------------
 include/linux/phylink.h   | 27 ++++++++++++++++++++++-----
 2 files changed, 29 insertions(+), 22 deletions(-)

diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index 69ca765485db..76ce96315c0c 100644
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -1205,6 +1205,8 @@ static void phylink_pcs_neg_mode(struct phylink *pl, struct phylink_pcs *pcs,
 	pl->act_link_an_mode = mode;
 }
 
+static void pcs_change_callback(void *priv, bool up);
+
 static void phylink_major_config(struct phylink *pl, bool restart,
 				  const struct phylink_link_state *state)
 {
@@ -1260,10 +1262,10 @@ static void phylink_major_config(struct phylink *pl, bool restart,
 		phylink_pcs_disable(pl->pcs);
 
 		if (pl->pcs)
-			pl->pcs->phylink = NULL;
-
-		pcs->phylink = pl;
+			pl->pcs->link_change_priv = NULL;
 
+		pcs->link_change = pcs_change_callback;
+		pcs->link_change_priv = pl;
 		pl->pcs = pcs;
 	}
 
@@ -2333,25 +2335,13 @@ void phylink_mac_change(struct phylink *pl, bool up)
 }
 EXPORT_SYMBOL_GPL(phylink_mac_change);
 
-/**
- * phylink_pcs_change() - notify phylink of a change to PCS link state
- * @pcs: pointer to &struct phylink_pcs
- * @up: indicates whether the link is currently up.
- *
- * The PCS driver should call this when the state of its link changes
- * (e.g. link failure, new negotiation results, etc.) Note: it should
- * not determine "up" by reading the BMSR. If in doubt about the link
- * state at interrupt time, then pass true if pcs_get_state() returns
- * the latched link-down state, otherwise pass false.
- */
-void phylink_pcs_change(struct phylink_pcs *pcs, bool up)
+static void pcs_change_callback(void *priv, bool up)
 {
-	struct phylink *pl = pcs->phylink;
+	struct phylink *pl = priv;
 
 	if (pl)
 		phylink_link_changed(pl, up, "pcs");
 }
-EXPORT_SYMBOL_GPL(phylink_pcs_change);
 
 static irqreturn_t phylink_link_handler(int irq, void *data)
 {
diff --git a/include/linux/phylink.h b/include/linux/phylink.h
index 1f5773ab5660..a16282ae746d 100644
--- a/include/linux/phylink.h
+++ b/include/linux/phylink.h
@@ -441,7 +441,8 @@ struct phylink_pcs_ops;
  * @supported_interfaces: describing which PHY_INTERFACE_MODE_xxx
  *                        are supported by this PCS.
  * @ops: a pointer to the &struct phylink_pcs_ops structure
- * @phylink: pointer to &struct phylink_config
+ * @link_change: callback for when the link changes
+ * @link_change_priv: first argument to @link_change
  * @poll: poll the PCS for link changes
  * @rxc_always_on: The MAC driver requires the reference clock
  *                 to always be on. Standalone PCS drivers which
@@ -451,13 +452,14 @@ struct phylink_pcs_ops;
  * This structure is designed to be embedded within the PCS private data,
  * and will be passed between phylink and the PCS.
  *
- * The @phylink member is private to phylink and must not be touched by
- * the PCS driver.
+ * @link_change, @link_change_priv, and @rxc_always_on will be filled in by
+ * phylink.
  */
 struct phylink_pcs {
 	DECLARE_PHY_INTERFACE_MASK(supported_interfaces);
 	const struct phylink_pcs_ops *ops;
-	struct phylink *phylink;
+	void (*link_change)(void *priv, bool up);
+	void *link_change_priv;
 	bool poll;
 	bool rxc_always_on;
 };
@@ -699,7 +701,22 @@ int phylink_set_fixed_link(struct phylink *,
 			   const struct phylink_link_state *);
 
 void phylink_mac_change(struct phylink *, bool up);
-void phylink_pcs_change(struct phylink_pcs *, bool up);
+/**
+ * phylink_pcs_change() - notify phylink of a change to PCS link state
+ * @pcs: pointer to &struct phylink_pcs
+ * @up: indicates whether the link is currently up.
+ *
+ * The PCS driver should call this when the state of its link changes
+ * (e.g. link failure, new negotiation results, etc.) Note: it should
+ * not determine "up" by reading the BMSR. If in doubt about the link
+ * state at interrupt time, then pass true if pcs_get_state() returns
+ * the latched link-down state, otherwise pass false.
+ */
+static inline void phylink_pcs_change(struct phylink_pcs *pcs, bool up)
+{
+	if (pcs->link_change)
+		pcs->link_change(pcs->link_change_priv, up);
+}
 
 int phylink_pcs_pre_init(struct phylink *pl, struct phylink_pcs *pcs);
 
-- 
2.35.1.1320.gc452695387.dirty