mac80211: allow mac80211 drivers to get to struct ieee80211_hw from wiphy

If a driver is given a wiphy and it wants to get to its private
mac80211 driver area it can use wiphy_to_ieee80211_hw() to get first
to its ieee80211_hw and then access the private structure via hw->priv. The
wiphy_priv() is already being used internally by mac80211 and drivers
should not use this. This can be helpful in a drivers reg_notifier().

Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

include/net/mac80211.h

@@ -989,6 +989,19 @@ struct ieee80211_hw {
 	u8 max_rate_tries;
 };
 
+/**
+ * wiphy_to_ieee80211_hw - return a mac80211 driver hw struct from a wiphy
+ *
+ * @wiphy: the &struct wiphy which we want to query
+ *
+ * mac80211 drivers can use this to get to their respective
+ * &struct ieee80211_hw. Drivers wishing to get to their own private
+ * structure can then access it via hw->priv. Note that mac802111 drivers should
+ * not use wiphy_priv() to try to get their private driver structure as this
+ * is already used internally by mac80211.
+ */
+struct ieee80211_hw *wiphy_to_ieee80211_hw(struct wiphy *wiphy);
+
 /**
  * SET_IEEE80211_DEV - set device for 802.11 hardware
  *

net/mac80211/util.c

@@ -41,6 +41,15 @@ const unsigned char rfc1042_header[] __aligned(2) =
 const unsigned char bridge_tunnel_header[] __aligned(2) =
 	{ 0xaa, 0xaa, 0x03, 0x00, 0x00, 0xf8 };
 
+struct ieee80211_hw *wiphy_to_ieee80211_hw(struct wiphy *wiphy)
+{
+	struct ieee80211_local *local;
+	BUG_ON(!wiphy);
+
+	local = wiphy_priv(wiphy);
+	return &local->hw;
+}
+EXPORT_SYMBOL(wiphy_to_ieee80211_hw);
 
 u8 *ieee80211_get_bssid(struct ieee80211_hdr *hdr, size_t len,
 			enum nl80211_iftype type)