ath5k: Implement mac80211 callback set_coverage_class

The callback sets slot time as specified in IEEE 802.11-2007 section
17.3.8.6 (for 20MHz channels only for now) and raises ACK and CTS
timeouts accordingly. The values are persistent, they are restored after
device reset.

Signed-off-by: Lukas Turek <8an@praha12.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath5k/ath5k.h

@@ -1063,6 +1063,7 @@ struct ath5k_hw {
 	u32			ah_cw_min;
 	u32			ah_cw_max;
 	u32			ah_limit_tx_retries;
+	u8			ah_coverage_class;
 
 	/* Antenna Control */
 	u32			ah_ant_ctl[AR5K_EEPROM_N_MODES][AR5K_ANT_MAX];
@@ -1200,6 +1201,7 @@ extern bool ath5k_eeprom_is_hb63(struct ath5k_hw *ah);
 
 /* Protocol Control Unit Functions */
 extern int ath5k_hw_set_opmode(struct ath5k_hw *ah);
+extern void ath5k_hw_set_coverage_class(struct ath5k_hw *ah, u8 coverage_class);
 /* BSSID Functions */
 extern int ath5k_hw_set_lladdr(struct ath5k_hw *ah, const u8 *mac);
 extern void ath5k_hw_set_associd(struct ath5k_hw *ah);

drivers/net/wireless/ath/ath5k/base.c

@@ -254,6 +254,8 @@ static void ath5k_bss_info_changed(struct ieee80211_hw *hw,
 		u32 changes);
 static void ath5k_sw_scan_start(struct ieee80211_hw *hw);
 static void ath5k_sw_scan_complete(struct ieee80211_hw *hw);
+static void ath5k_set_coverage_class(struct ieee80211_hw *hw,
+		u8 coverage_class);
 
 static const struct ieee80211_ops ath5k_hw_ops = {
 	.tx 		= ath5k_tx,
@@ -274,6 +276,7 @@ static const struct ieee80211_ops ath5k_hw_ops = {
 	.bss_info_changed = ath5k_bss_info_changed,
 	.sw_scan_start	= ath5k_sw_scan_start,
 	.sw_scan_complete = ath5k_sw_scan_complete,
+	.set_coverage_class = ath5k_set_coverage_class,
 };
 
 /*
@@ -3262,3 +3265,22 @@ static void ath5k_sw_scan_complete(struct ieee80211_hw *hw)
 	ath5k_hw_set_ledstate(sc->ah, sc->assoc ?
 		AR5K_LED_ASSOC : AR5K_LED_INIT);
 }
+
+/**
+ * ath5k_set_coverage_class - Set IEEE 802.11 coverage class
+ *
+ * @hw: struct ieee80211_hw pointer
+ * @coverage_class: IEEE 802.11 coverage class number
+ *
+ * Mac80211 callback. Sets slot time, ACK timeout and CTS timeout for given
+ * coverage class. The values are persistent, they are restored after device
+ * reset.
+ */
+static void ath5k_set_coverage_class(struct ieee80211_hw *hw, u8 coverage_class)
+{
+	struct ath5k_softc *sc = hw->priv;
+
+	mutex_lock(&sc->lock);
+	ath5k_hw_set_coverage_class(sc->ah, coverage_class);
+	mutex_unlock(&sc->lock);
+}

drivers/net/wireless/ath/ath5k/pcu.c

@@ -285,6 +285,42 @@ unsigned int ath5k_hw_get_clockrate(struct ath5k_hw *ah)
 	return clock;
 }
 
+/**
+ * ath5k_hw_get_default_slottime - Get the default slot time for current mode
+ *
+ * @ah: The &struct ath5k_hw
+ */
+unsigned int ath5k_hw_get_default_slottime(struct ath5k_hw *ah)
+{
+	struct ieee80211_channel *channel = ah->ah_current_channel;
+
+	if (channel->hw_value & CHANNEL_TURBO)
+		return 6; /* both turbo modes */
+
+	if (channel->hw_value & CHANNEL_CCK)
+		return 20; /* 802.11b */
+
+	return 9; /* 802.11 a/g */
+}
+
+/**
+ * ath5k_hw_get_default_sifs - Get the default SIFS for current mode
+ *
+ * @ah: The &struct ath5k_hw
+ */
+unsigned int ath5k_hw_get_default_sifs(struct ath5k_hw *ah)
+{
+	struct ieee80211_channel *channel = ah->ah_current_channel;
+
+	if (channel->hw_value & CHANNEL_TURBO)
+		return 8; /* both turbo modes */
+
+	if (channel->hw_value & CHANNEL_5GHZ)
+		return 16; /* 802.11a */
+
+	return 10; /* 802.11 b/g */
+}
+
 /**
  * ath5k_hw_set_lladdr - Set station id
  *
@@ -1094,3 +1130,24 @@ int ath5k_hw_set_key_lladdr(struct ath5k_hw *ah, u16 entry, const u8 *mac)
 	return 0;
 }
 
+/**
+ * ath5k_hw_set_coverage_class - Set IEEE 802.11 coverage class
+ *
+ * @ah: The &struct ath5k_hw
+ * @coverage_class: IEEE 802.11 coverage class number
+ *
+ * Sets slot time, ACK timeout and CTS timeout for given coverage class.
+ */
+void ath5k_hw_set_coverage_class(struct ath5k_hw *ah, u8 coverage_class)
+{
+	/* As defined by IEEE 802.11-2007 17.3.8.6 */
+	int slot_time = ath5k_hw_get_default_slottime(ah) + 3 * coverage_class;
+	int ack_timeout = ath5k_hw_get_default_sifs(ah) + slot_time;
+	int cts_timeout = ack_timeout;
+
+	ath5k_hw_set_slot_time(ah, slot_time);
+	ath5k_hw_set_ack_timeout(ah, ack_timeout);
+	ath5k_hw_set_cts_timeout(ah, cts_timeout);
+
+	ah->ah_coverage_class = coverage_class;
+}

drivers/net/wireless/ath/ath5k/reset.c

@@ -1316,6 +1316,10 @@ int ath5k_hw_reset(struct ath5k_hw *ah, enum nl80211_iftype op_mode,
 	/* Restore antenna mode */
 	ath5k_hw_set_antenna_mode(ah, ah->ah_ant_mode);
 
+	/* Restore slot time and ACK timeouts */
+	if (ah->ah_coverage_class > 0)
+		ath5k_hw_set_coverage_class(ah, ah->ah_coverage_class);
+
 	/*
 	 * Configure QCUs/DCUs
 	 */