mac80211: enable spatial multiplexing powersave

Enable spatial multiplexing in mac80211 by telling the
driver what to do and, where necessary, sending action
frames to the AP to update the requested SMPS mode.

Also includes a trivial implementation for hwsim that
just logs the requested mode.

For now, the userspace interface is in debugfs only,
and let you toggle the requested mode at any time.

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

drivers/net/wireless/mac80211_hwsim.c

@@ -618,12 +618,26 @@ static int mac80211_hwsim_config(struct ieee80211_hw *hw, u32 changed)
 {
 	struct mac80211_hwsim_data *data = hw->priv;
 	struct ieee80211_conf *conf = &hw->conf;
-
-	printk(KERN_DEBUG "%s:%s (freq=%d idle=%d ps=%d)\n",
+	static const char *chantypes[4] = {
+		[NL80211_CHAN_NO_HT] = "noht",
+		[NL80211_CHAN_HT20] = "ht20",
+		[NL80211_CHAN_HT40MINUS] = "ht40-",
+		[NL80211_CHAN_HT40PLUS] = "ht40+",
+	};
+	static const char *smps_modes[IEEE80211_SMPS_NUM_MODES] = {
+		[IEEE80211_SMPS_AUTOMATIC] = "auto",
+		[IEEE80211_SMPS_OFF] = "off",
+		[IEEE80211_SMPS_STATIC] = "static",
+		[IEEE80211_SMPS_DYNAMIC] = "dynamic",
+	};
+
+	printk(KERN_DEBUG "%s:%s (freq=%d/%s idle=%d ps=%d smps=%s)\n",
 	       wiphy_name(hw->wiphy), __func__,
 	       conf->channel->center_freq,
+	       chantypes[conf->channel_type],
 	       !!(conf->flags & IEEE80211_CONF_IDLE),
-	       !!(conf->flags & IEEE80211_CONF_PS));
+	       !!(conf->flags & IEEE80211_CONF_PS),
+	       smps_modes[conf->smps_mode]);
 
 	data->idle = !!(conf->flags & IEEE80211_CONF_IDLE);
 
@@ -1082,7 +1096,9 @@ static int __init init_mac80211_hwsim(void)
 			BIT(NL80211_IFTYPE_MESH_POINT);
 
 		hw->flags = IEEE80211_HW_MFP_CAPABLE |
-			    IEEE80211_HW_SIGNAL_DBM;
+			    IEEE80211_HW_SIGNAL_DBM |
+			    IEEE80211_HW_SUPPORTS_STATIC_SMPS |
+			    IEEE80211_HW_SUPPORTS_DYNAMIC_SMPS;
 
 		/* ask mac80211 to reserve space for magic */
 		hw->vif_data_size = sizeof(struct hwsim_vif_priv);

include/linux/ieee80211.h

@@ -707,6 +707,10 @@ struct ieee80211_mgmt {
 					u8 action;
 					u8 trans_id[WLAN_SA_QUERY_TR_ID_LEN];
 				} __attribute__ ((packed)) sa_query;
+				struct {
+					u8 action;
+					u8 smps_control;
+				} __attribute__ ((packed)) ht_smps;
 			} u;
 		} __attribute__ ((packed)) action;
 	} u;
@@ -824,6 +828,7 @@ struct ieee80211_ht_cap {
 #define IEEE80211_HT_CAP_LDPC_CODING		0x0001
 #define IEEE80211_HT_CAP_SUP_WIDTH_20_40	0x0002
 #define IEEE80211_HT_CAP_SM_PS			0x000C
+#define		IEEE80211_HT_CAP_SM_PS_SHIFT	2
 #define IEEE80211_HT_CAP_GRN_FLD		0x0010
 #define IEEE80211_HT_CAP_SGI_20			0x0020
 #define IEEE80211_HT_CAP_SGI_40			0x0040
@@ -839,6 +844,7 @@ struct ieee80211_ht_cap {
 /* 802.11n HT capability AMPDU settings (for ampdu_params_info) */
 #define IEEE80211_HT_AMPDU_PARM_FACTOR		0x03
 #define IEEE80211_HT_AMPDU_PARM_DENSITY		0x1C
+#define		IEEE80211_HT_AMPDU_PARM_DENSITY_SHIFT	2
 
 /*
  * Maximum length of AMPDU that the STA can receive.
@@ -922,12 +928,17 @@ struct ieee80211_ht_info {
 #define IEEE80211_MAX_AMPDU_BUF 0x40
 
 
-/* Spatial Multiplexing Power Save Modes */
+/* Spatial Multiplexing Power Save Modes (for capability) */
 #define WLAN_HT_CAP_SM_PS_STATIC	0
 #define WLAN_HT_CAP_SM_PS_DYNAMIC	1
 #define WLAN_HT_CAP_SM_PS_INVALID	2
 #define WLAN_HT_CAP_SM_PS_DISABLED	3
 
+/* for SM power control field lower two bits */
+#define WLAN_HT_SMPS_CONTROL_DISABLED	0
+#define WLAN_HT_SMPS_CONTROL_STATIC	1
+#define WLAN_HT_SMPS_CONTROL_DYNAMIC	3
+
 /* Authentication algorithms */
 #define WLAN_AUTH_OPEN 0
 #define WLAN_AUTH_SHARED_KEY 1
@@ -1150,6 +1161,18 @@ enum ieee80211_spectrum_mgmt_actioncode {
 	WLAN_ACTION_SPCT_CHL_SWITCH = 4,
 };
 
+/* HT action codes */
+enum ieee80211_ht_actioncode {
+	WLAN_HT_ACTION_NOTIFY_CHANWIDTH = 0,
+	WLAN_HT_ACTION_SMPS = 1,
+	WLAN_HT_ACTION_PSMP = 2,
+	WLAN_HT_ACTION_PCO_PHASE = 3,
+	WLAN_HT_ACTION_CSI = 4,
+	WLAN_HT_ACTION_NONCOMPRESSED_BF = 5,
+	WLAN_HT_ACTION_COMPRESSED_BF = 6,
+	WLAN_HT_ACTION_ASEL_IDX_FEEDBACK = 7,
+};
+
 /* Security key length */
 enum ieee80211_key_len {
 	WLAN_KEY_LEN_WEP40 = 5,

include/net/mac80211.h

@@ -597,8 +597,10 @@ enum ieee80211_conf_flags {
  * @IEEE80211_CONF_CHANGE_CHANNEL: the channel/channel_type changed
  * @IEEE80211_CONF_CHANGE_RETRY_LIMITS: retry limits changed
  * @IEEE80211_CONF_CHANGE_IDLE: Idle flag changed
+ * @IEEE80211_CONF_CHANGE_SMPS: Spatial multiplexing powersave mode changed
  */
 enum ieee80211_conf_changed {
+	IEEE80211_CONF_CHANGE_SMPS		= BIT(1),
 	IEEE80211_CONF_CHANGE_LISTEN_INTERVAL	= BIT(2),
 	IEEE80211_CONF_CHANGE_MONITOR		= BIT(3),
 	IEEE80211_CONF_CHANGE_PS		= BIT(4),
@@ -608,6 +610,21 @@ enum ieee80211_conf_changed {
 	IEEE80211_CONF_CHANGE_IDLE		= BIT(8),
 };
 
+/**
+ * enum ieee80211_smps_mode - spatial multiplexing power save mode
+ *
+ * @
+ */
+enum ieee80211_smps_mode {
+	IEEE80211_SMPS_AUTOMATIC,
+	IEEE80211_SMPS_OFF,
+	IEEE80211_SMPS_STATIC,
+	IEEE80211_SMPS_DYNAMIC,
+
+	/* keep last */
+	IEEE80211_SMPS_NUM_MODES,
+};
+
 /**
  * struct ieee80211_conf - configuration of the device
  *
@@ -636,6 +653,10 @@ enum ieee80211_conf_changed {
  * @short_frame_max_tx_count: Maximum number of transmissions for a "short"
  *    frame, called "dot11ShortRetryLimit" in 802.11, but actually means the
  *    number of transmissions not the number of retries
+ *
+ * @smps_mode: spatial multiplexing powersave mode; note that
+ *	%IEEE80211_SMPS_STATIC is used when the device is not
+ *	configured for an HT channel
  */
 struct ieee80211_conf {
 	u32 flags;
@@ -648,6 +669,7 @@ struct ieee80211_conf {
 
 	struct ieee80211_channel *channel;
 	enum nl80211_channel_type channel_type;
+	enum ieee80211_smps_mode smps_mode;
 };
 
 /**
@@ -930,6 +952,16 @@ enum ieee80211_tkip_key_type {
  * @IEEE80211_HW_BEACON_FILTER:
  *	Hardware supports dropping of irrelevant beacon frames to
  *	avoid waking up cpu.
+ *
+ * @IEEE80211_HW_SUPPORTS_STATIC_SMPS:
+ *	Hardware supports static spatial multiplexing powersave,
+ *	ie. can turn off all but one chain even on HT connections
+ *	that should be using more chains.
+ *
+ * @IEEE80211_HW_SUPPORTS_DYNAMIC_SMPS:
+ *	Hardware supports dynamic spatial multiplexing powersave,
+ *	ie. can turn off all but one chain and then wake the rest
+ *	up as required after, for example, rts/cts handshake.
  */
 enum ieee80211_hw_flags {
 	IEEE80211_HW_HAS_RATE_CONTROL			= 1<<0,
@@ -947,6 +979,8 @@ enum ieee80211_hw_flags {
 	IEEE80211_HW_SUPPORTS_DYNAMIC_PS		= 1<<12,
 	IEEE80211_HW_MFP_CAPABLE			= 1<<13,
 	IEEE80211_HW_BEACON_FILTER			= 1<<14,
+	IEEE80211_HW_SUPPORTS_STATIC_SMPS		= 1<<15,
+	IEEE80211_HW_SUPPORTS_DYNAMIC_SMPS		= 1<<16,
 };
 
 /**
@@ -1214,6 +1248,31 @@ ieee80211_get_alt_retry_rate(const struct ieee80211_hw *hw,
  * signal strength threshold checking.
  */
 
+/**
+ * DOC: Spatial multiplexing power save
+ *
+ * SMPS (Spatial multiplexing power save) is a mechanism to conserve
+ * power in an 802.11n implementation. For details on the mechanism
+ * and rationale, please refer to 802.11 (as amended by 802.11n-2009)
+ * "11.2.3 SM power save".
+ *
+ * The mac80211 implementation is capable of sending action frames
+ * to update the AP about the station's SMPS mode, and will instruct
+ * the driver to enter the specific mode. It will also announce the
+ * requested SMPS mode during the association handshake. Hardware
+ * support for this feature is required, and can be indicated by
+ * hardware flags.
+ *
+ * The default mode will be "automatic", which nl80211/cfg80211
+ * defines to be dynamic SMPS in (regular) powersave, and SMPS
+ * turned off otherwise.
+ *
+ * To support this feature, the driver must set the appropriate
+ * hardware support flags, and handle the SMPS flag to the config()
+ * operation. It will then with this mechanism be instructed to
+ * enter the requested SMPS mode while associated to an HT AP.
+ */
+
 /**
  * DOC: Frame filtering
  *

net/mac80211/cfg.c

@@ -1318,6 +1318,50 @@ static int ieee80211_testmode_cmd(struct wiphy *wiphy, void *data, int len)
 }
 #endif
 
+int __ieee80211_request_smps(struct ieee80211_sub_if_data *sdata,
+			     enum ieee80211_smps_mode smps_mode)
+{
+	const u8 *ap;
+	enum ieee80211_smps_mode old_req;
+	int err;
+
+	old_req = sdata->u.mgd.req_smps;
+	sdata->u.mgd.req_smps = smps_mode;
+
+	if (old_req == smps_mode &&
+	    smps_mode != IEEE80211_SMPS_AUTOMATIC)
+		return 0;
+
+	/*
+	 * If not associated, or current association is not an HT
+	 * association, there's no need to send an action frame.
+	 */
+	if (!sdata->u.mgd.associated ||
+	    sdata->local->oper_channel_type == NL80211_CHAN_NO_HT) {
+		mutex_lock(&sdata->local->iflist_mtx);
+		ieee80211_recalc_smps(sdata->local, sdata);
+		mutex_unlock(&sdata->local->iflist_mtx);
+		return 0;
+	}
+
+	ap = sdata->u.mgd.associated->cbss.bssid;
+
+	if (smps_mode == IEEE80211_SMPS_AUTOMATIC) {
+		if (sdata->u.mgd.powersave)
+			smps_mode = IEEE80211_SMPS_DYNAMIC;
+		else
+			smps_mode = IEEE80211_SMPS_OFF;
+	}
+
+	/* send SM PS frame to AP */
+	err = ieee80211_send_smps_action(sdata, smps_mode,
+					 ap, ap);
+	if (err)
+		sdata->u.mgd.req_smps = old_req;
+
+	return err;
+}
+
 static int ieee80211_set_power_mgmt(struct wiphy *wiphy, struct net_device *dev,
 				    bool enabled, int timeout)
 {
@@ -1335,6 +1379,11 @@ static int ieee80211_set_power_mgmt(struct wiphy *wiphy, struct net_device *dev,
 	sdata->u.mgd.powersave = enabled;
 	conf->dynamic_ps_timeout = timeout;
 
+	/* no change, but if automatic follow powersave */
+	mutex_lock(&sdata->u.mgd.mtx);
+	__ieee80211_request_smps(sdata, sdata->u.mgd.req_smps);
+	mutex_unlock(&sdata->u.mgd.mtx);
+
 	if (local->hw.flags & IEEE80211_HW_SUPPORTS_DYNAMIC_PS)
 		ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);