ieee802154: Internal PAN management

Introduce structures to describe peer devices in a PAN as well as a few
related helpers. We basically care about:
- Our unique parent after associating with a coordinator.
- Peer devices, children, which successfully associated with us.

Signed-off-by: Miquel Raynal <[e-mail]>
Acked-by: Stefan Schmidt <[e-mail]>
Acked-by: Alexander Aring <[e-mail]>
Link: https://lore.kernel.org/linux-wpan/[e-mail]

include/net/cfg802154.h

···
 };
 
 /**
+ * struct ieee802154_pan_device - PAN device information
+ * @pan_id: the PAN ID of this device
+ * @mode: the preferred mode to reach the device
+ * @short_addr: the short address of this device
+ * @extended_addr: the extended address of this device
+ * @node: the list node
+ */
+struct ieee802154_pan_device {
+	__le16 pan_id;
+	u8 mode;
+	__le16 short_addr;
+	__le64 extended_addr;
+	struct list_head node;
+};
+
+/**
  * struct cfg802154_scan_request - Scan request
  *
  * @type: type of scan to be performed
···
 
 	/* fallback for acknowledgment bit setting */
 	bool ackreq;
+
+	/* Associations */
+	struct mutex association_lock;
+	struct ieee802154_pan_device *parent;
+	struct list_head children;
 };
 
 #define to_phy(_dev)	container_of(_dev, struct wpan_phy, dev)
···
 
 void ieee802154_configure_durations(struct wpan_phy *phy,
 				    unsigned int page, unsigned int channel);
+
+/**
+ * cfg802154_device_is_associated - Checks whether we are associated to any device
+ * @wpan_dev: the wpan device
+ * @return: true if we are associated
+ */
+bool cfg802154_device_is_associated(struct wpan_dev *wpan_dev);
+
+/**
+ * cfg802154_device_is_parent - Checks if a device is our coordinator
+ * @wpan_dev: the wpan device
+ * @target: the expected parent
+ * @return: true if @target is our coordinator
+ */
+bool cfg802154_device_is_parent(struct wpan_dev *wpan_dev,
+				struct ieee802154_addr *target);
+
+/**
+ * cfg802154_device_is_child - Checks whether a device is associated to us
+ * @wpan_dev: the wpan device
+ * @target: the expected child
+ * @return: the PAN device
+ */
+struct ieee802154_pan_device *
+cfg802154_device_is_child(struct wpan_dev *wpan_dev,
+			  struct ieee802154_addr *target);
 
 #endif /* __NET_CFG802154_H */

net/ieee802154/Makefile

···
 obj-y += 6lowpan/
 
 ieee802154-y := netlink.o nl-mac.o nl-phy.o nl_policy.o core.o \
-                header_ops.o sysfs.o nl802154.o trace.o
+                header_ops.o sysfs.o nl802154.o trace.o pan.o
 ieee802154_socket-y := socket.o
 
 CFLAGS_trace.o := -I$(src)

net/ieee802154/core.c

···
 		wpan_dev->identifier = ++rdev->wpan_dev_id;
 		list_add_rcu(&wpan_dev->list, &rdev->wpan_dev_list);
 		rdev->devlist_generation++;
+		mutex_init(&wpan_dev->association_lock);
+		INIT_LIST_HEAD(&wpan_dev->children);
 
 		wpan_dev->netdev = dev;
 		break;

net/ieee802154/pan.c

···
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * IEEE 802.15.4 PAN management
+ *
+ * Copyright (C) 2023 Qorvo US, Inc
+ * Authors:
+ *   - David Girault <[e-mail]>
+ *   - Miquel Raynal <[e-mail]>
+ */
+
+#include <linux/kernel.h>
+#include <net/cfg802154.h>
+#include <net/af_ieee802154.h>
+
+/* Checks whether a device address matches one from the PAN list.
+ * This helper is meant to be used only during PAN management, when we expect
+ * extended addresses to be used.
+ */
+static bool cfg802154_pan_device_is_matching(struct ieee802154_pan_device *pan_dev,
+					     struct ieee802154_addr *ext_dev)
+{
+	if (!pan_dev || !ext_dev)
+		return false;
+
+	if (ext_dev->mode == IEEE802154_ADDR_SHORT)
+		return false;
+
+	return pan_dev->extended_addr == ext_dev->extended_addr;
+}
+
+bool cfg802154_device_is_associated(struct wpan_dev *wpan_dev)
+{
+	bool is_assoc;
+
+	mutex_lock(&wpan_dev->association_lock);
+	is_assoc = !list_empty(&wpan_dev->children) || wpan_dev->parent;
+	mutex_unlock(&wpan_dev->association_lock);
+
+	return is_assoc;
+}
+
+bool cfg802154_device_is_parent(struct wpan_dev *wpan_dev,
+				struct ieee802154_addr *target)
+{
+	lockdep_assert_held(&wpan_dev->association_lock);
+
+	return cfg802154_pan_device_is_matching(wpan_dev->parent, target);
+}
+
+struct ieee802154_pan_device *
+cfg802154_device_is_child(struct wpan_dev *wpan_dev,
+			  struct ieee802154_addr *target)
+{
+	struct ieee802154_pan_device *child;
+
+	lockdep_assert_held(&wpan_dev->association_lock);
+
+	list_for_each_entry(child, &wpan_dev->children, node)
+		if (cfg802154_pan_device_is_matching(child, target))
+			return child;
+
+	return NULL;
+}