Phonet: back-end for autoconfigured addresses

In some cases, the network device driver knows what layer-3 address the
device should have. This adds support for the Phonet stack to
automatically request from the driver and add that address to the
network device.
Signed-off-by: NRémi Denis-Courmont <remi.denis-courmont@nokia.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/linux/phonet.h

@@ -170,4 +170,21 @@ static inline __u8 pn_sockaddr_get_resource(const struct sockaddr_pn *spn)
 	return spn->spn_resource;
 }
 
+/* Phonet device ioctl requests */
+#ifdef __KERNEL__
+#define SIOCPNGAUTOCONF		(SIOCDEVPRIVATE + 0)
+
+struct if_phonet_autoconf {
+	uint8_t device;
+};
+
+struct if_phonet_req {
+	char ifr_phonet_name[16];
+	union {
+		struct if_phonet_autoconf ifru_phonet_autoconf;
+	} ifr_ifru;
+};
+#define ifr_phonet_autoconf ifr_ifru.ifru_phonet_autoconf
+#endif /* __KERNEL__ */
+
 #endif

net/phonet/pn_dev.c

@@ -28,6 +28,7 @@
 #include <linux/netdevice.h>
 #include <linux/phonet.h>
 #include <linux/proc_fs.h>
+#include <linux/if_arp.h>
 #include <net/sock.h>
 #include <net/netns/generic.h>
 #include <net/phonet/pn_dev.h>
@@ -195,14 +196,37 @@ int phonet_address_lookup(struct net *net, u8 addr)
 	return err;
 }
 
+/* automatically configure a Phonet device, if supported */
+static int phonet_device_autoconf(struct net_device *dev)
+{
+	struct if_phonet_req req;
+	int ret;
+
+	if (!dev->netdev_ops->ndo_do_ioctl)
+		return -EOPNOTSUPP;
+
+	ret = dev->netdev_ops->ndo_do_ioctl(dev, (struct ifreq *)&req,
+						SIOCPNGAUTOCONF);
+	if (ret < 0)
+		return ret;
+	return phonet_address_add(dev, req.ifr_phonet_autoconf.device);
+}
+
 /* notify Phonet of device events */
 static int phonet_device_notify(struct notifier_block *me, unsigned long what,
 				void *arg)
 {
 	struct net_device *dev = arg;
 
-	if (what == NETDEV_UNREGISTER)
+	switch (what) {
+	case NETDEV_REGISTER:
+		if (dev->type == ARPHRD_PHONET)
+			phonet_device_autoconf(dev);
+		break;
+	case NETDEV_UNREGISTER:
 		phonet_device_destroy(dev);
+		break;
+	}
 	return 0;
 
 }