cfg80211: keep track of supported interface modes

It is obviously good for userspace to know up front which
interface modes a given piece of hardware might support (even
if adding such an interface might fail later because of
concurrency issues), so let's make cfg80211 aware of that.
For good measure, disallow adding interfaces in all other
modes so drivers don't forget to announce support for one mode
when they add it.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Stephen Blackheath <tramp.enshrine.stephen@blacksapphire.com>
Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/include/net/wireless.h b/include/net/wireless.h
index 9324f8d..1dc8ec3 100644
--- a/include/net/wireless.h
+++ b/include/net/wireless.h
@@ -185,6 +185,9 @@
 	/* permanent MAC address */
 	u8 perm_addr[ETH_ALEN];
 
+	/* Supported interface modes, OR together BIT(NL80211_IFTYPE_...) */
+	u16 interface_modes;
+
 	/* If multiple wiphys are registered and you're handed e.g.
 	 * a regular netdev with assigned ieee80211_ptr, you won't
 	 * know whether it points to a wiphy your driver has registered