[net-next PATCH v4 04/11] net: phylink: add phylink_release_pcs() to externally release a PCS

[Christian Marangi <ansuelsmth@gmail.com>]

Add phylink_release_pcs() to externally release a PCS from a phylink
instance. This can be used to handle case when a single PCS needs to be
removed and the phylink instance needs to be refreshed.

On calling phylink_release_pcs(), the PCS will be removed from the
phylink internal PCS list and the phylink supported_interfaces value is
reparsed with the remaining PCS interfaces.

Also a phylink resolve is triggered to handle the PCS removal.

A flag to make phylink resolve reconfigure the interface (even if it
didn't change) is also added. This is needed to handle the special
case when the current PCS used by phylink is removed and a major_config
is needed to propagae the configuration change. With this option
enabled we also force mac_config even if the PHY link is not up for
the in-band case.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
---
 drivers/net/phy/phylink.c | 58 ++++++++++++++++++++++++++++++++++++++-
 include/linux/phylink.h   |  2 ++
 2 files changed, 59 insertions(+), 1 deletion(-)

diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index 95d7e06dee56..2f28c4c83062 100644
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -84,6 +84,7 @@ struct phylink {
 	bool link_failed;
 	bool suspend_link_up;
 	bool major_config_failed;
+	bool reconfig_interface;
 	bool mac_supports_eee_ops;
 	bool mac_supports_eee;
 	bool phy_enable_tx_lpi;
@@ -895,6 +896,55 @@ static void phylink_resolve_an_pause(struct phylink_link_state *state)
 	}
 }
 
+/**
+ * phylink_release_pcs - Removes a PCS from the phylink PCS available list
+ * @pcs: a pointer to the phylink_pcs struct to be released
+ *
+ * This function release a PCS from the phylink PCS available list if
+ * actually in use. It also refreshes the supported interfaces of the
+ * phylink instance by copying the supported interfaces from the phylink
+ * conf and merging the supported interfaces of the remaining available PCS
+ * in the list and trigger a resolve.
+ */
+void phylink_release_pcs(struct phylink_pcs *pcs)
+{
+	struct phylink *pl;
+
+	ASSERT_RTNL();
+
+	pl = pcs->phylink;
+	if (!pl)
+		return;
+
+	list_del(&pcs->list);
+	pcs->phylink = NULL;
+
+	/* Check if we are removing the PCS currently
+	 * in use by phylink. If this is the case,
+	 * force phylink resolve to reconfigure the interface
+	 * mode and set the phylink PCS to NULL.
+	 */
+	if (pl->pcs == pcs) {
+		mutex_lock(&pl->state_mutex);
+
+		pl->reconfig_interface = true;
+		pl->pcs = NULL;
+
+		mutex_unlock(&pl->state_mutex);
+	}
+
+	/* Refresh supported interfaces */
+	phy_interface_copy(pl->supported_interfaces,
+			   pl->config->supported_interfaces);
+	list_for_each_entry(pcs, &pl->pcs_list, list)
+		phy_interface_or(pl->supported_interfaces,
+				 pl->supported_interfaces,
+				 pcs->supported_interfaces);
+
+	phylink_run_resolve(pl);
+}
+EXPORT_SYMBOL_GPL(phylink_release_pcs);
+
 static unsigned int phylink_pcs_inband_caps(struct phylink_pcs *pcs,
 				    phy_interface_t interface)
 {
@@ -1688,6 +1738,10 @@ static void phylink_resolve(struct work_struct *w)
 		if (pl->phydev)
 			link_state.link &= pl->phy_state.link;
 
+		/* Force mac_config if we need to reconfig the interface */
+		if (pl->reconfig_interface)
+			mac_config = true;
+
 		/* Only update if the PHY link is up */
 		if (pl->phydev && pl->phy_state.link) {
 			/* If the interface has changed, force a link down
@@ -1722,7 +1776,8 @@ static void phylink_resolve(struct work_struct *w)
 		phylink_apply_manual_flow(pl, &link_state);
 
 	if (mac_config) {
-		if (link_state.interface != pl->link_config.interface) {
+		if (link_state.interface != pl->link_config.interface ||
+		    pl->reconfig_interface) {
 			/* The interface has changed, force the link down and
 			 * then reconfigure.
 			 */
@@ -1732,6 +1787,7 @@ static void phylink_resolve(struct work_struct *w)
 			}
 			phylink_major_config(pl, false, &link_state);
 			pl->link_config.interface = link_state.interface;
+			pl->reconfig_interface = false;
 		}
 	}
 
diff --git a/include/linux/phylink.h b/include/linux/phylink.h
index ef0b5a0729c8..c5496c063b6a 100644
--- a/include/linux/phylink.h
+++ b/include/linux/phylink.h
@@ -717,6 +717,8 @@ void phylink_disconnect_phy(struct phylink *);
 int phylink_set_fixed_link(struct phylink *,
 			   const struct phylink_link_state *);
 
+void phylink_release_pcs(struct phylink_pcs *pcs);
+
 void phylink_mac_change(struct phylink *, bool up);
 void phylink_pcs_change(struct phylink_pcs *, bool up);
 
-- 
2.48.1