[PATCH net-next v13 06/12] net: phylink: support late PCS provider attach

@@ -69,6 +69,10 @@ fwnode_pcs_add_provider(struct fwnode_handle *fwnode,
 
 	mutex_unlock(&fwnode_pcs_mutex);
 
+	blocking_notifier_call_chain(&fwnode_pcs_notify_list,
+				     FWNODE_PCS_PROVIDER_ADD,
+				     pp);
+
 	pr_debug("Added pcs provider from %pfwf\n", fwnode);
 
 	return pp;

@@ -201,6 +205,24 @@ struct phylink_pcs *fwnode_pcs_get(const struct fwnode_handle *fwnode, unsigned
 }
 EXPORT_SYMBOL_GPL(fwnode_pcs_get);
 
+struct phylink_pcs *fwnode_pcs_get_from_provider(struct fwnode_pcs_provider *provider,
+						 const struct fwnode_handle *fwnode,
+						 int index)
+{
+	struct fwnode_reference_args pcsspec;
+	struct phylink_pcs *pcs;
+	int ret;
+
+	ret = fwnode_parse_pcsspec(fwnode, index, NULL, &pcsspec);
+	if (ret)
+		return ERR_PTR(ret);
+
+	pcs = __fwnode_pcs_get_from_pcsspec_provider(&pcsspec, provider);
+	fwnode_handle_put(pcsspec.fwnode);
+	return pcs;
+}
+EXPORT_SYMBOL_GPL(fwnode_pcs_get_from_provider);
+
 bool fwnode_pcs_matches_provider(struct fwnode_pcs_provider *provider,
 				 const struct fwnode_handle *fwnode,
 				 struct phylink_pcs *pl_pcs)

@@ -1926,6 +1926,27 @@ int phylink_set_fixed_link(struct phylink *pl,
 }
 EXPORT_SYMBOL_GPL(phylink_set_fixed_link);
 
+static void phylink_add_pcs(struct phylink *pl, struct phylink_pcs *pcs)
+{
+	struct phylink_pcs *tmp;
+
+	/*
+	 * Make sure state mutex is locked to protect concurrent
+	 * access to phylink instance PCS list from
+	 * initial fill_available_pcs and late PCS attach
+	 */
+	lockdep_assert_held(&pl->state_mutex);
+
+	list_for_each_entry(tmp, &pl->pcs_list, list)
+		if (tmp == pcs)
+			return;
+
+	list_add_tail(&pcs->list, &pl->pcs_list);
+
+	/* Link PCS to phylink */
+	pcs->phylink = pl;
+}
+
 static int phylink_fill_available_pcs(struct phylink *pl,
 				      struct phylink_config *config)
 {

@@ -1958,7 +1979,7 @@ static int phylink_fill_available_pcs(struct phylink *pl,
 		if (!pcs)
 			continue;
 
-		list_add_tail(&pcs->list, &pl->pcs_list);
+		phylink_add_pcs(pl, pcs);
 	}
 
 	mutex_unlock(&pl->state_mutex);

@@ -2004,27 +2025,57 @@ static int pcs_provider_notify(struct notifier_block *self,
 	struct fwnode_pcs_provider *pp = data;
 	struct phylink_pcs *pcs, *tmp;
 	bool resolve = false;
+	int count, i;
 
-	rtnl_lock();
+	/*
+	 * On PCS provider deletion hold rtnl lock as one of
+	 * PCS can be currently in use by the phylink instance
+	 * and ethtool OPs can reference it.
+	 */
+	if (val == FWNODE_PCS_PROVIDER_DEL)
+		rtnl_lock();
 
 	mutex_lock(&pl->state_mutex);
 
-	/*
-	 * Loop all the PCS for phylink instance and check if
-	 * this notification is relevant for some of them.
-	 */
-	list_for_each_entry_safe(pcs, tmp, &pl->pcs_list, list) {
-		if (!fwnode_pcs_matches_provider(pp, pl->fwnode, pcs))
-			continue;
+	switch (val) {
+	case FWNODE_PCS_PROVIDER_ADD:
+		count = fwnode_phylink_pcs_count(pl->fwnode);
+		for (i = 0; i < count; i++) {
+			pcs = fwnode_pcs_get_from_provider(pp, pl->fwnode, i);
+			if (IS_ERR(pcs))
+				continue;
+
+			phylink_add_pcs(pl, pcs);
+			resolve = true;
+		}
+
+		/* Force an interface reconfig if major config fail */
+		if (resolve && pl->major_config_failed)
+			pl->force_major_config = true;
 
-		phylink_del_pcs(pl, pcs);
-		resolve = true;
+		break;
+	case FWNODE_PCS_PROVIDER_DEL:
+		/*
+		 * Loop all the PCS for phylink instance and check if
+		 * this notification is relevant for some of them.
+		 */
+		list_for_each_entry_safe(pcs, tmp, &pl->pcs_list, list) {
+			if (!fwnode_pcs_matches_provider(pp, pl->fwnode, pcs))
+				continue;
+
+			phylink_del_pcs(pl, pcs);
+			resolve = true;
+		}
+		break;
 	}
 
 	/* Exit early if nothing has changed */
 	if (!resolve) {
 		mutex_unlock(&pl->state_mutex);
-		rtnl_unlock();
+
+		if (val == FWNODE_PCS_PROVIDER_DEL)
+			rtnl_unlock();
+
 		return NOTIFY_DONE;
 	}
 

@@ -2038,7 +2089,8 @@ static int pcs_provider_notify(struct notifier_block *self,
 
 	mutex_unlock(&pl->state_mutex);
 
-	rtnl_unlock();
+	if (val == FWNODE_PCS_PROVIDER_DEL)
+		rtnl_unlock();
 
 	phylink_run_resolve(pl);
 

@@ -2121,10 +2173,6 @@ struct phylink *phylink_create(struct phylink_config *config,
 
 	mutex_lock(&pl->state_mutex);
 
-	/* Link available PCS to phylink */
-	list_for_each_entry(pcs, &pl->pcs_list, list)
-		pcs->phylink = pl;
-
 	phy_interface_copy(pl->supported_interfaces,
 			   pl->config->supported_interfaces);
 

@@ -5,6 +5,7 @@
 #include <linux/phylink.h>
 
 enum fwnode_pcs_notify_event {
+	FWNODE_PCS_PROVIDER_ADD,
 	FWNODE_PCS_PROVIDER_DEL,
 };
 

@@ -50,6 +51,28 @@ int unregister_fwnode_pcs_notifier(struct notifier_block *nb);
 struct phylink_pcs *fwnode_pcs_get(const struct fwnode_handle *fwnode,
 				   unsigned int index);
 
+/**
+ * fwnode_pcs_get_from_provider() - Retrieve a PCS from a specific provider
+ * @provider: PCS provider to use
+ * @fwnode: firmware node
+ * @index: index fwnode PCS handle in firmware node
+ *
+ * Get a PCS from the firmware node at index specifically provided by
+ * passed PCS provider.
+ *
+ * Unlike fwnode_pcs_get(), this function does not search the global list of
+ * PCS providers. The caller must provide the provider responsible for the
+ * referenced PCS.
+ *
+ * Returns: a pointer to the phylink_pcs or a negative error pointer. Can
+ * return -ENODEV if the PCS is not present in global providers list (either
+ * due to driver still needs to be probed or it failed to probe/removed) or
+ * can return -EINVAL if the PCS provider doesn't expose any PCS for the fwnode.
+ */
+struct phylink_pcs *fwnode_pcs_get_from_provider(struct fwnode_pcs_provider *provider,
+						 const struct fwnode_handle *fwnode,
+						 int index);
+
 /**
  * fwnode_pcs_matches_provider() - Check whether a PCS belongs to a provider
  * @provider: PCS provider to check

@@ -120,6 +143,14 @@ static inline struct phylink_pcs *fwnode_pcs_get(const struct fwnode_handle *fwn
 	return ERR_PTR(-ENOENT);
 }
 
+static inline struct phylink_pcs *
+fwnode_pcs_get_from_provider(struct fwnode_pcs_provider *provider,
+			     const struct fwnode_handle *fwnode,
+			     int index)
+{
+	return ERR_PTR(-ENOENT);
+}
+
 static inline bool fwnode_pcs_matches_provider(struct fwnode_pcs_provider *provider,
 					       const struct fwnode_handle *fwnode,
 					       struct phylink_pcs *pl_pcs)