mac80211: extend/document powersave API

This modifies hardware flags for powersave to support three different
flags:
 * IEEE80211_HW_SUPPORTS_PS - indicates general PS support
 * IEEE80211_HW_PS_NULLFUNC_STACK - indicates nullfunc sending in software
 * IEEE80211_HW_SUPPORTS_DYNAMIC_PS - indicates dynamic PS on the device

It also adds documentation for all this which explains how to set the
various flags.

Additionally, it fixes a few things:
 * a spot where && was used to test flags
 * enable CONF_PS only when associated again

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

Documentation/DocBook/mac80211.tmpl

@@ -17,8 +17,7 @@
     </authorgroup>
 
     <copyright>
-      <year>2007</year>
-      <year>2008</year>
+      <year>2007-2009</year>
       <holder>Johannes Berg</holder>
     </copyright>
 
@@ -223,6 +222,11 @@ usage should require reading the full document.
 !Finclude/net/mac80211.h ieee80211_key_flags
     </chapter>
 
+    <chapter id="powersave">
+      <title>Powersave support</title>
+!Pinclude/net/mac80211.h Powersave support
+    </chapter>
+
     <chapter id="qos">
       <title>Multiple queues and QoS support</title>
       <para>TBD</para>

drivers/net/wireless/iwlwifi/iwl-core.c

@@ -805,7 +805,8 @@ int iwl_setup_mac(struct iwl_priv *priv)
 	/* Tell mac80211 our characteristics */
 	hw->flags = IEEE80211_HW_SIGNAL_DBM |
 		    IEEE80211_HW_NOISE_DBM |
-		    IEEE80211_HW_AMPDU_AGGREGATION;
+		    IEEE80211_HW_AMPDU_AGGREGATION |
+		    IEEE80211_HW_SUPPORTS_PS;
 	hw->wiphy->interface_modes =
 		BIT(NL80211_IFTYPE_STATION) |
 		BIT(NL80211_IFTYPE_ADHOC);

drivers/net/wireless/rt2x00/rt2400pci.c

@@ -1449,7 +1449,9 @@ static int rt2400pci_probe_hw_mode(struct rt2x00_dev *rt2x00dev)
 	 * Initialize all hw fields.
 	 */
 	rt2x00dev->hw->flags = IEEE80211_HW_HOST_BROADCAST_PS_BUFFERING |
-			       IEEE80211_HW_SIGNAL_DBM;
+			       IEEE80211_HW_SIGNAL_DBM |
+			       IEEE80211_HW_SUPPORTS_PS |
+			       IEEE80211_HW_PS_NULLFUNC_STACK;
 	rt2x00dev->hw->extra_tx_headroom = 0;
 
 	SET_IEEE80211_DEV(rt2x00dev->hw, rt2x00dev->dev);

drivers/net/wireless/rt2x00/rt2500pci.c

@@ -1749,7 +1749,9 @@ static int rt2500pci_probe_hw_mode(struct rt2x00_dev *rt2x00dev)
 	 * Initialize all hw fields.
 	 */
 	rt2x00dev->hw->flags = IEEE80211_HW_HOST_BROADCAST_PS_BUFFERING |
-			       IEEE80211_HW_SIGNAL_DBM;
+			       IEEE80211_HW_SIGNAL_DBM |
+			       IEEE80211_HW_SUPPORTS_PS |
+			       IEEE80211_HW_PS_NULLFUNC_STACK;
 
 	rt2x00dev->hw->extra_tx_headroom = 0;
 

drivers/net/wireless/rt2x00/rt2500usb.c

@@ -1801,7 +1801,9 @@ static int rt2500usb_probe_hw_mode(struct rt2x00_dev *rt2x00dev)
 	rt2x00dev->hw->flags =
 	    IEEE80211_HW_RX_INCLUDES_FCS |
 	    IEEE80211_HW_HOST_BROADCAST_PS_BUFFERING |
-	    IEEE80211_HW_SIGNAL_DBM;
+	    IEEE80211_HW_SIGNAL_DBM |
+	    IEEE80211_HW_SUPPORTS_PS |
+	    IEEE80211_HW_PS_NULLFUNC_STACK;
 
 	rt2x00dev->hw->extra_tx_headroom = TXD_DESC_SIZE;
 

drivers/net/wireless/rt2x00/rt61pci.c

@@ -2556,7 +2556,9 @@ static int rt61pci_probe_hw_mode(struct rt2x00_dev *rt2x00dev)
 	 */
 	rt2x00dev->hw->flags =
 	    IEEE80211_HW_HOST_BROADCAST_PS_BUFFERING |
-	    IEEE80211_HW_SIGNAL_DBM;
+	    IEEE80211_HW_SIGNAL_DBM |
+	    IEEE80211_HW_SUPPORTS_PS |
+	    IEEE80211_HW_PS_NULLFUNC_STACK;
 	rt2x00dev->hw->extra_tx_headroom = 0;
 
 	SET_IEEE80211_DEV(rt2x00dev->hw, rt2x00dev->dev);

drivers/net/wireless/rt2x00/rt73usb.c

@@ -2077,7 +2077,9 @@ static int rt73usb_probe_hw_mode(struct rt2x00_dev *rt2x00dev)
 	 */
 	rt2x00dev->hw->flags =
 	    IEEE80211_HW_HOST_BROADCAST_PS_BUFFERING |
-	    IEEE80211_HW_SIGNAL_DBM;
+	    IEEE80211_HW_SIGNAL_DBM |
+	    IEEE80211_HW_SUPPORTS_PS |
+	    IEEE80211_HW_PS_NULLFUNC_STACK;
 	rt2x00dev->hw->extra_tx_headroom = TXD_DESC_SIZE;
 
 	SET_IEEE80211_DEV(rt2x00dev->hw, rt2x00dev->dev);

include/net/mac80211.h

@@ -850,10 +850,15 @@ enum ieee80211_tkip_key_type {
  * @IEEE80211_HW_AMPDU_AGGREGATION:
  *	Hardware supports 11n A-MPDU aggregation.
  *
- * @IEEE80211_HW_NO_STACK_DYNAMIC_PS:
- *	Hardware which has dynamic power save support, meaning
- *	that power save is enabled in idle periods, and don't need support
- *	from stack.
+ * @IEEE80211_HW_SUPPORTS_PS:
+ *	Hardware has power save support (i.e. can go to sleep).
+ *
+ * @IEEE80211_HW_PS_NULLFUNC_STACK:
+ *	Hardware requires nullfunc frame handling in stack, implies
+ *	stack support for dynamic PS.
+ *
+ * @IEEE80211_HW_SUPPORTS_DYNAMIC_PS:
+ *	Hardware has support for dynamic PS.
  */
 enum ieee80211_hw_flags {
 	IEEE80211_HW_RX_INCLUDES_FCS			= 1<<1,
@@ -866,7 +871,9 @@ enum ieee80211_hw_flags {
 	IEEE80211_HW_NOISE_DBM				= 1<<8,
 	IEEE80211_HW_SPECTRUM_MGMT			= 1<<9,
 	IEEE80211_HW_AMPDU_AGGREGATION			= 1<<10,
-	IEEE80211_HW_NO_STACK_DYNAMIC_PS		= 1<<11,
+	IEEE80211_HW_SUPPORTS_PS			= 1<<11,
+	IEEE80211_HW_PS_NULLFUNC_STACK			= 1<<12,
+	IEEE80211_HW_SUPPORTS_DYNAMIC_PS		= 1<<13,
 };
 
 /**
@@ -1052,6 +1059,42 @@ ieee80211_get_alt_retry_rate(const struct ieee80211_hw *hw,
  * handler is software decryption with wrap around of iv16.
  */
 
+/**
+ * DOC: Powersave support
+ *
+ * mac80211 has support for various powersave implementations.
+ *
+ * First, it can support hardware that handles all powersaving by
+ * itself, such hardware should simply set the %IEEE80211_HW_SUPPORTS_PS
+ * hardware flag. In that case, it will be told about the desired
+ * powersave mode depending on the association status, and the driver
+ * must take care of sending nullfunc frames when necessary, i.e. when
+ * entering and leaving powersave mode. The driver is required to look at
+ * the AID in beacons and signal to the AP that it woke up when it finds
+ * traffic directed to it. This mode supports dynamic PS by simply
+ * enabling/disabling PS.
+ *
+ * Additionally, such hardware may set the %IEEE80211_HW_SUPPORTS_DYNAMIC_PS
+ * flag to indicate that it can support dynamic PS mode itself (see below).
+ *
+ * Other hardware designs cannot send nullfunc frames by themselves and also
+ * need software support for parsing the TIM bitmap. This is also supported
+ * by mac80211 by combining the %IEEE80211_HW_SUPPORTS_PS and
+ * %IEEE80211_HW_PS_NULLFUNC_STACK flags. The hardware is of course still
+ * required to pass up beacons. Additionally, in this case, mac80211 will
+ * wake up the hardware when multicast traffic is announced in the beacon.
+ *
+ * FIXME: I don't think we can be fast enough in software when we want to
+ *	  receive multicast traffic?
+ *
+ * Dynamic powersave mode is an extension to normal powersave mode in which
+ * the hardware stays awake for a user-specified period of time after sending
+ * a frame so that reply frames need not be buffered and therefore delayed
+ * to the next wakeup. This can either be supported by hardware, in which case
+ * the driver needs to look at the @dynamic_ps_timeout hardware configuration
+ * value, or by the stack if all nullfunc handling is in the stack.
+ */
+
 /**
  * DOC: Frame filtering
  *

net/mac80211/mlme.c

@@ -775,17 +775,17 @@ static void ieee80211_set_associated(struct ieee80211_sub_if_data *sdata,
 	bss_info_changed |= BSS_CHANGED_BASIC_RATES;
 	ieee80211_bss_info_change_notify(sdata, bss_info_changed);
 
-	if (local->powersave &&
-			!(local->hw.flags & IEEE80211_HW_NO_STACK_DYNAMIC_PS)) {
-		if (local->hw.conf.dynamic_ps_timeout > 0)
+	if (local->powersave) {
+		if (!(local->hw.flags & IEEE80211_HW_SUPPORTS_DYNAMIC_PS) &&
+		    local->hw.conf.dynamic_ps_timeout > 0) {
 			mod_timer(&local->dynamic_ps_timer, jiffies +
 				  msecs_to_jiffies(
 					local->hw.conf.dynamic_ps_timeout));
-		else {
-			ieee80211_send_nullfunc(local, sdata, 1);
+		} else {
+			if (local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK)
+				ieee80211_send_nullfunc(local, sdata, 1);
 			conf->flags |= IEEE80211_CONF_PS;
-			ieee80211_hw_config(local,
-					    IEEE80211_CONF_CHANGE_PS);
+			ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
 		}
 	}
 
@@ -1779,16 +1779,14 @@ static void ieee80211_rx_mgmt_beacon(struct ieee80211_sub_if_data *sdata,
 	ieee80211_sta_wmm_params(local, ifsta, elems.wmm_param,
 				 elems.wmm_param_len);
 
-	if (!(local->hw.flags & IEEE80211_HW_NO_STACK_DYNAMIC_PS)) {
+	if (local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK &&
+	    local->hw.conf.flags & IEEE80211_CONF_PS) {
 		directed_tim = check_tim(&elems, ifsta->aid, &is_mc);
 
 		if (directed_tim || is_mc) {
-			if (local->hw.conf.flags && IEEE80211_CONF_PS) {
-				local->hw.conf.flags &= ~IEEE80211_CONF_PS;
-				ieee80211_hw_config(local,
-						IEEE80211_CONF_CHANGE_PS);
-				ieee80211_send_nullfunc(local, sdata, 0);
-			}
+			local->hw.conf.flags &= ~IEEE80211_CONF_PS;
+			ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
+			ieee80211_send_nullfunc(local, sdata, 0);
 		}
 	}
 
@@ -2694,9 +2692,10 @@ void ieee80211_dynamic_ps_enable_work(struct work_struct *work)
 	if (local->hw.conf.flags & IEEE80211_CONF_PS)
 		return;
 
-	ieee80211_send_nullfunc(local, sdata, 1);
-	local->hw.conf.flags |= IEEE80211_CONF_PS;
+	if (local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK)
+		ieee80211_send_nullfunc(local, sdata, 1);
 
+	local->hw.conf.flags |= IEEE80211_CONF_PS;
 	ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
 }
 

net/mac80211/tx.c

@@ -1295,7 +1295,7 @@ int ieee80211_master_start_xmit(struct sk_buff *skb, struct net_device *dev)
 		return 0;
 	}
 
-	if (!(local->hw.flags & IEEE80211_HW_NO_STACK_DYNAMIC_PS) &&
+	if ((local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK) &&
 	    local->hw.conf.dynamic_ps_timeout > 0) {
 		if (local->hw.conf.flags & IEEE80211_CONF_PS) {
 			ieee80211_stop_queues_by_reason(&local->hw,

net/mac80211/wext.c

@@ -837,6 +837,9 @@ static int ieee80211_ioctl_siwpower(struct net_device *dev,
 	int ret = 0, timeout = 0;
 	bool ps;
 
+	if (!(local->hw.flags & IEEE80211_HW_SUPPORTS_PS))
+		return -EOPNOTSUPP;
+
 	if (sdata->vif.type != NL80211_IFTYPE_STATION)
 		return -EINVAL;
 
@@ -862,32 +865,37 @@ static int ieee80211_ioctl_siwpower(struct net_device *dev,
 	if (wrq->flags & IW_POWER_TIMEOUT)
 		timeout = wrq->value / 1000;
 
-set:
+ set:
 	if (ps == local->powersave && timeout == conf->dynamic_ps_timeout)
 		return ret;
 
 	local->powersave = ps;
 	conf->dynamic_ps_timeout = timeout;
 
-	if (local->hw.flags & IEEE80211_HW_NO_STACK_DYNAMIC_PS) {
+	if (local->hw.flags & IEEE80211_HW_SUPPORTS_DYNAMIC_PS)
 		ret = ieee80211_hw_config(local,
 					  IEEE80211_CONF_CHANGE_DYNPS_TIMEOUT);
-	} else if (sdata->u.sta.flags & IEEE80211_STA_ASSOCIATED) {
-		if (conf->dynamic_ps_timeout > 0)
-			mod_timer(&local->dynamic_ps_timer, jiffies +
-				  msecs_to_jiffies(conf->dynamic_ps_timeout));
-		else {
-			if (local->powersave) {
+
+	if (!(sdata->u.sta.flags & IEEE80211_STA_ASSOCIATED))
+		return ret;
+
+	if (conf->dynamic_ps_timeout > 0 &&
+	    !(local->hw.flags & IEEE80211_HW_SUPPORTS_DYNAMIC_PS)) {
+		mod_timer(&local->dynamic_ps_timer, jiffies +
+			  msecs_to_jiffies(conf->dynamic_ps_timeout));
+	} else {
+		if (local->powersave) {
+			if (local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK)
 				ieee80211_send_nullfunc(local, sdata, 1);
-				conf->flags |= IEEE80211_CONF_PS;
-				ret = ieee80211_hw_config(local,
-						IEEE80211_CONF_CHANGE_PS);
-			} else {
-				conf->flags &= ~IEEE80211_CONF_PS;
-				ret = ieee80211_hw_config(local,
-						IEEE80211_CONF_CHANGE_PS);
+			conf->flags |= IEEE80211_CONF_PS;
+			ret = ieee80211_hw_config(local,
+					IEEE80211_CONF_CHANGE_PS);
+		} else {
+			conf->flags &= ~IEEE80211_CONF_PS;
+			ret = ieee80211_hw_config(local,
+					IEEE80211_CONF_CHANGE_PS);
+			if (local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK)
 				ieee80211_send_nullfunc(local, sdata, 0);
-			}
 		}
 	}