ieee802154: add support for listen-before-talk in wpan_phy

Listen-before-talk is an alternative to CSMA in uncoordinated networks
and prescribed by european regulations if one wants to have a device
with radio duty cycles above 10% (or less in some bands). Add a phy
property to enable/disable LBT in the phy, including support in the
at86rf230 driver for RF212 chips.

Signed-off-by: Phoebe Buckheister <phoebe.buckheister@itwm.fraunhofer.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/mac802154/ieee802154_dev.c b/net/mac802154/ieee802154_dev.c
index 9eb49e0..56338c8 100644
--- a/net/mac802154/ieee802154_dev.c
+++ b/net/mac802154/ieee802154_dev.c
@@ -175,6 +175,16 @@
 	return priv->ops->set_txpower(&priv->hw, db);
 }
 
+static int mac802154_set_lbt(struct wpan_phy *phy, bool on)
+{
+	struct mac802154_priv *priv = wpan_phy_priv(phy);
+
+	if (!priv->ops->set_lbt)
+		return -ENOTSUPP;
+
+	return priv->ops->set_lbt(&priv->hw, on);
+}
+
 struct ieee802154_dev *
 ieee802154_alloc_device(size_t priv_data_len, struct ieee802154_ops *ops)
 {
@@ -253,6 +263,7 @@
 	priv->phy->add_iface = mac802154_add_iface;
 	priv->phy->del_iface = mac802154_del_iface;
 	priv->phy->set_txpower = mac802154_set_txpower;
+	priv->phy->set_lbt = mac802154_set_lbt;
 
 	rc = wpan_phy_register(priv->phy);
 	if (rc < 0)