ieee802154: add TX power control to wpan_phy

Replace the current u8 transmit_power in wpan_phy with s8 transmit_power.
The u8 field contained the actual tx power and a tolerance field,
which no physical radio every used. Adjust sysfs entries to keep
compatibility with userspace, give tolerances of +-1dB statically there.

This patch only adds support for this in the at86rf230 driver and the
RF212 chip. Configuration calculation for RF212 is also somewhat basic,
but does the job - the RF212 datasheet gives a large table with
suggested values for combinations of TX power and page/channel, if this
does not work well, we might have to copy the whole table.

Signed-off-by: Phoebe Buckheister <phoebe.buckheister@itwm.fraunhofer.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/wpan-phy.h b/include/net/wpan-phy.h
index b52bda8..47fc0c1 100644
--- a/include/net/wpan-phy.h
+++ b/include/net/wpan-phy.h
@@ -37,14 +37,14 @@
 	struct mutex pib_lock;
 
 	/*
-	 * This is a PIB according to 802.15.4-2006.
+	 * This is a PIB according to 802.15.4-2011.
 	 * We do not provide timing-related variables, as they
 	 * aren't used outside of driver
 	 */
 	u8 current_channel;
 	u8 current_page;
 	u32 channels_supported[32];
-	u8 transmit_power;
+	s8 transmit_power;
 	u8 cca_mode;
 
 	struct device dev;
@@ -54,6 +54,8 @@
 					const char *name, int type);
 	void (*del_iface)(struct wpan_phy *phy, struct net_device *dev);
 
+	int (*set_txpower)(struct wpan_phy *phy, int db);
+
 	char priv[0] __attribute__((__aligned__(NETDEV_ALIGN)));
 };