[PATCHv2 1/2] cfg80211: Add support to configure station specific RSSI threshold for AP mode

[Tamizh chelvam <tamizhr@codeaurora.org>]

Add infrastructure to configure station specific RSSI threshold
configuration to monitor station's signal strength variation.
This configuration will be useful for the application like
steering which requires change in the station's current signal
strength.

New NL80211_CMD_STA_MON introduced to configure the RSSI threshold
using NL80211_ATTR_CQM nested attributes. The MAC address of
a station is passed in NL80211_ATTR_MAC. And NL80211_ATTR_STA_MON_FIXED_THOLD
introduced to have this RSSI threshold as a fixed(not modifying the
low and high threshold upon crossing the threshold) or moving(modifying
low and high threshold upon crossing the threshold) thresholds.
Depends on the application's use case user can have either fixed or
moving RSSI range thresholds.

cfg80211_sta_mon_rssi_notify introduced to notify change in the
station's signal stregnth cross event using NL80211_CMD_NOTIFY_STA_MON.
Driver supporting this feature should advertise
NL80211_EXT_FEATURE_STA_MON_RSSI_CONFIG feature flag.

Signed-off-by: Tamizh chelvam <tamizhr@codeaurora.org>
---
 include/net/cfg80211.h       |   39 ++++++++++
 include/uapi/linux/nl80211.h |   21 ++++++
 net/wireless/nl80211.c       |  169 +++++++++++++++++++++++++++++++++++-------
 net/wireless/rdev-ops.h      |   13 ++++
 net/wireless/trace.h         |   22 ++++++
 5 files changed, 237 insertions(+), 27 deletions(-)

diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index 7f2739a..a8838d7 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -3075,6 +3075,20 @@ struct cfg80211_pmsr_request {
 };
 
 /**
+ * struct cfg80211_sta_mon - Configure station monitor parameters
+ * @rssi_tholds - array of RSSI thresholds for the station
+ * @rssi_hyst - RSSI hysterisis
+ * @n_rssi_tholds - Number of RSSI thresholds
+ * @fixed_thold - Fixed thresholds limit used for the station
+ */
+struct cfg80211_sta_mon {
+	s32 *rssi_tholds;
+	u32 rssi_hyst;
+	int n_rssi_tholds;
+	u8 fixed_thold;
+};
+
+/**
  * struct cfg80211_ops - backend description for wireless configuration
  *
  * This struct is registered by fullmac card drivers and/or wireless stacks
@@ -3411,6 +3425,12 @@ struct cfg80211_pmsr_request {
  *	Statistics should be cumulative, currently no way to reset is provided.
  * @start_pmsr: start peer measurement (e.g. FTM)
  * @abort_pmsr: abort peer measurement
+ *
+ * @set_sta_mon_rssi_config: Configure  RSSI threshold for a station.
+ *     After configuration, the driver should (soon) send an event indicating
+ *     the current level of a station is above/below the configured threshold;
+ *     this may need some care when the configuration is changed
+ *     (without first being disabled.)
  */
 struct cfg80211_ops {
 	int	(*suspend)(struct wiphy *wiphy, struct cfg80211_wowlan *wow);
@@ -3725,6 +3745,9 @@ struct cfg80211_ops {
 			      struct cfg80211_pmsr_request *request);
 	void	(*abort_pmsr)(struct wiphy *wiphy, struct wireless_dev *wdev,
 			      struct cfg80211_pmsr_request *request);
+	int	(*set_sta_mon_rssi_config)(struct wiphy *wiphy,
+				struct net_device *dev, const u8 *addr,
+				const struct cfg80211_sta_mon *sta_mon_cfg);
 };
 
 /*
@@ -6322,6 +6345,22 @@ bool cfg80211_rx_control_port(struct net_device *dev,
 			      struct sk_buff *skb, bool unencrypted);
 
 /**
+ * cfg80211_sta_mon_rssi_notify - Station's rssi out of range event
+ * @dev: network device
+ * @peer: Station's mac address
+ * @rssi_event: the triggered RSSI event
+ * @rssi_level: new RSSI level value or 0 if not available
+ * @gfp: context flags
+ *
+ * This function is called when a configured rssi threshold reached event
+ * occurs for a station.
+ */
+void
+cfg80211_sta_mon_rssi_notify(struct net_device *dev, const u8 *peer,
+			     enum nl80211_cqm_rssi_threshold_event rssi_event,
+			     s32 rssi_level, gfp_t gfp);
+
+/**
  * cfg80211_cqm_rssi_notify - connection quality monitoring rssi event
  * @dev: network device
  * @rssi_event: the triggered RSSI event
diff --git a/include/uapi/linux/nl80211.h b/include/uapi/linux/nl80211.h
index dd4f86e..4b0586b 100644
--- a/include/uapi/linux/nl80211.h
+++ b/include/uapi/linux/nl80211.h
@@ -1065,6 +1065,12 @@
  *	indicated by %NL80211_ATTR_WIPHY_FREQ and other attributes
  *	determining the width and type.
  *
+ * @NL80211_CMD_SET_STA_MON: This command is used to configure station's
+ *	connection monitoring notification trigger levels. This uses nested
+ *	attribute %NL80211_ATTR_CQM with %NL80211_ATTR_CQM_* sub-attributes.
+ * @NL80211_CMD_NOTIFY_STA_MON: This is used as an event to notify
+ *	the user space that a trigger level was reached for a station.
+ *
  * @NL80211_CMD_MAX: highest used command number
  * @__NL80211_CMD_AFTER_LAST: internal use
  */
@@ -1285,6 +1291,9 @@ enum nl80211_commands {
 
 	NL80211_CMD_NOTIFY_RADAR,
 
+	NL80211_CMD_SET_STA_MON,
+	NL80211_CMD_NOTIFY_STA_MON,
+
 	/* add new commands above here */
 
 	/* used to define NL80211_CMD_MAX below */
@@ -2308,6 +2317,12 @@ enum nl80211_commands {
  * @NL80211_ATTR_AIRTIME_WEIGHT: Station's weight when scheduled by the airtime
  *	scheduler.
  *
+ * @NL80211_ATTR_STA_MON_FIXED_THOLD: This u8 attribute is used with
+ *	%NL80211_CMD_SET_STA_MON to indicate driver that the monitoring
+ *	threshold is fixed(not modifying the low and high threshold upon
+ *	crossing the threshold) or moving(modifying low and high threshold
+ *	upon crossing the threshold) thresholds.
+ *
  * @NUM_NL80211_ATTR: total number of nl80211_attrs available
  * @NL80211_ATTR_MAX: highest attribute number currently defined
  * @__NL80211_ATTR_AFTER_LAST: internal use
@@ -2759,6 +2774,8 @@ enum nl80211_attrs {
 
 	NL80211_ATTR_AIRTIME_WEIGHT,
 
+	NL80211_ATTR_STA_MON_FIXED_THOLD,
+
 	/* add attributes here, update the policy in nl80211.c */
 
 	__NL80211_ATTR_AFTER_LAST,
@@ -5343,6 +5360,9 @@ enum nl80211_feature_flags {
  * @NL80211_EXT_FEATURE_AP_PMKSA_CACHING: Driver/device supports PMKSA caching
  *	(set/del PMKSA operations) in AP mode.
  *
+ * @NL80211_EXT_FEATURE_STA_MON_RSSI_CONFIG: Driver supports monitoring
+ *	station's RSSI threshold value should adveritise this flag.
+ *
  * @NUM_NL80211_EXT_FEATURES: number of extended features.
  * @MAX_NL80211_EXT_FEATURES: highest extended feature index.
  */
@@ -5384,6 +5404,7 @@ enum nl80211_ext_feature_index {
 	NL80211_EXT_FEATURE_ENABLE_FTM_RESPONDER,
 	NL80211_EXT_FEATURE_AIRTIME_FAIRNESS,
 	NL80211_EXT_FEATURE_AP_PMKSA_CACHING,
+	NL80211_EXT_FEATURE_STA_MON_RSSI_CONFIG,
 
 	/* add new features before the definition below */
 	NUM_NL80211_EXT_FEATURES,
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index a3cc039..73e41c0 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -292,6 +292,17 @@ static int validate_ie_attr(const struct nlattr *attr,
 		NLA_POLICY_NESTED_ARRAY(nl80211_psmr_peer_attr_policy),
 };
 
+static const struct nla_policy
+nl80211_attr_cqm_policy[NL80211_ATTR_CQM_MAX + 1] = {
+	[NL80211_ATTR_CQM_RSSI_THOLD] = { .type = NLA_BINARY },
+	[NL80211_ATTR_CQM_RSSI_HYST] = { .type = NLA_U32 },
+	[NL80211_ATTR_CQM_RSSI_THRESHOLD_EVENT] = { .type = NLA_U32 },
+	[NL80211_ATTR_CQM_TXE_RATE] = { .type = NLA_U32 },
+	[NL80211_ATTR_CQM_TXE_PKTS] = { .type = NLA_U32 },
+	[NL80211_ATTR_CQM_TXE_INTVL] = { .type = NLA_U32 },
+	[NL80211_ATTR_CQM_RSSI_LEVEL] = { .type = NLA_S32 },
+};
+
 const struct nla_policy nl80211_policy[NUM_NL80211_ATTR] = {
 	[NL80211_ATTR_WIPHY] = { .type = NLA_U32 },
 	[NL80211_ATTR_WIPHY_NAME] = { .type = NLA_NUL_STRING,
@@ -402,7 +413,10 @@ static int validate_ie_attr(const struct nlattr *attr,
 	[NL80211_ATTR_PS_STATE] = NLA_POLICY_RANGE(NLA_U32,
 						   NL80211_PS_DISABLED,
 						   NL80211_PS_ENABLED),
-	[NL80211_ATTR_CQM] = { .type = NLA_NESTED, },
+	[NL80211_ATTR_CQM] = {
+		.type = NLA_NESTED,
+		.validation_data = nl80211_attr_cqm_policy,
+	 },
 	[NL80211_ATTR_LOCAL_STATE_CHANGE] = { .type = NLA_FLAG },
 	[NL80211_ATTR_AP_ISOLATE] = { .type = NLA_U8 },
 	[NL80211_ATTR_WIPHY_TX_POWER_SETTING] = { .type = NLA_U32 },
@@ -553,6 +567,7 @@ static int validate_ie_attr(const struct nlattr *attr,
 	[NL80211_ATTR_PEER_MEASUREMENTS] =
 		NLA_POLICY_NESTED(nl80211_pmsr_attr_policy),
 	[NL80211_ATTR_AIRTIME_WEIGHT] = NLA_POLICY_MIN(NLA_U16, 1),
+	[NL80211_ATTR_STA_MON_FIXED_THOLD] = { .type = NLA_U8 },
 };
 
 /* policy for the key attributes */
@@ -10382,17 +10397,6 @@ static int nl80211_get_power_save(struct sk_buff *skb, struct genl_info *info)
 	return err;
 }
 
-static const struct nla_policy
-nl80211_attr_cqm_policy[NL80211_ATTR_CQM_MAX + 1] = {
-	[NL80211_ATTR_CQM_RSSI_THOLD] = { .type = NLA_BINARY },
-	[NL80211_ATTR_CQM_RSSI_HYST] = { .type = NLA_U32 },
-	[NL80211_ATTR_CQM_RSSI_THRESHOLD_EVENT] = { .type = NLA_U32 },
-	[NL80211_ATTR_CQM_TXE_RATE] = { .type = NLA_U32 },
-	[NL80211_ATTR_CQM_TXE_PKTS] = { .type = NLA_U32 },
-	[NL80211_ATTR_CQM_TXE_INTVL] = { .type = NLA_U32 },
-	[NL80211_ATTR_CQM_RSSI_LEVEL] = { .type = NLA_S32 },
-};
-
 static int nl80211_set_cqm_txe(struct genl_info *info,
 			       u32 rate, u32 pkts, u32 intvl)
 {
@@ -10473,23 +10477,33 @@ static int cfg80211_cqm_rssi_update(struct cfg80211_registered_device *rdev,
 	return rdev_set_cqm_rssi_range_config(rdev, dev, low, high);
 }
 
-static int nl80211_set_cqm_rssi(struct genl_info *info,
-				const s32 *thresholds, int n_thresholds,
-				u32 hysteresis)
+static int nl80211_validate_rssi_tholds(const s32 *thresholds, int n_tholds)
 {
-	struct cfg80211_registered_device *rdev = info->user_ptr[0];
-	struct net_device *dev = info->user_ptr[1];
-	struct wireless_dev *wdev = dev->ieee80211_ptr;
-	int i, err;
+	int i;
 	s32 prev = S32_MIN;
 
 	/* Check all values negative and sorted */
-	for (i = 0; i < n_thresholds; i++) {
+	for (i = 0; i < n_tholds; i++) {
 		if (thresholds[i] > 0 || thresholds[i] <= prev)
 			return -EINVAL;
 
 		prev = thresholds[i];
 	}
+	return 0;
+}
+
+static int nl80211_set_cqm_rssi(struct genl_info *info,
+				const s32 *thresholds, int n_thresholds,
+				u32 hysteresis)
+{
+	struct cfg80211_registered_device *rdev = info->user_ptr[0];
+	struct net_device *dev = info->user_ptr[1];
+	struct wireless_dev *wdev = dev->ieee80211_ptr;
+	int err;
+
+	err = nl80211_validate_rssi_tholds(thresholds, n_thresholds);
+	if (err)
+		return err;
 
 	if (wdev->iftype != NL80211_IFTYPE_STATION &&
 	    wdev->iftype != NL80211_IFTYPE_P2P_CLIENT)
@@ -10552,7 +10566,7 @@ static int nl80211_set_cqm(struct sk_buff *skb, struct genl_info *info)
 		return -EINVAL;
 
 	err = nla_parse_nested(attrs, NL80211_ATTR_CQM_MAX, cqm,
-			       nl80211_attr_cqm_policy, info->extack);
+			       NULL, NULL);
 	if (err)
 		return err;
 
@@ -13253,6 +13267,63 @@ static int nl80211_get_ftm_responder_stats(struct sk_buff *skb,
 	return -ENOBUFS;
 }
 
+static int nl80211_set_sta_mon(struct sk_buff *skb, struct genl_info *info)
+{
+	struct cfg80211_registered_device *rdev = info->user_ptr[0];
+	struct net_device *dev = info->user_ptr[1];
+	struct nlattr *attrs[NL80211_ATTR_CQM_MAX + 1];
+	struct cfg80211_sta_mon sta_mon_config = {};
+	struct nlattr *sta_mon;
+	u8 *addr = NULL;
+	int err;
+
+	if (dev->ieee80211_ptr->iftype != NL80211_IFTYPE_AP &&
+	    dev->ieee80211_ptr->iftype != NL80211_IFTYPE_P2P_GO)
+		return -ENOTSUPP;
+
+	sta_mon = info->attrs[NL80211_ATTR_CQM];
+	if (!sta_mon || !info->attrs[NL80211_ATTR_MAC])
+		return -EINVAL;
+
+	err = nla_parse_nested(attrs, NL80211_ATTR_CQM_MAX, sta_mon,
+			       NULL, NULL);
+	if (err)
+		return err;
+
+	addr = nla_data(info->attrs[NL80211_ATTR_MAC]);
+	sta_mon_config.fixed_thold =
+		!!nla_get_u8(info->attrs[NL80211_ATTR_STA_MON_FIXED_THOLD]);
+
+	if (attrs[NL80211_ATTR_CQM_RSSI_THOLD] &&
+	    attrs[NL80211_ATTR_CQM_RSSI_HYST]) {
+		int len = nla_len(attrs[NL80211_ATTR_CQM_RSSI_THOLD]);
+
+		sta_mon_config.rssi_tholds =
+			nla_data(attrs[NL80211_ATTR_CQM_RSSI_THOLD]);
+		sta_mon_config.rssi_hyst =
+			nla_get_u32(attrs[NL80211_ATTR_CQM_RSSI_HYST]);
+
+		if (!rdev->ops->set_sta_mon_rssi_config ||
+		    !wiphy_ext_feature_isset(&rdev->wiphy,
+				     NL80211_EXT_FEATURE_STA_MON_RSSI_CONFIG))
+			return -EOPNOTSUPP;
+
+		if (len % 4)
+			return -EINVAL;
+
+		sta_mon_config.n_rssi_tholds = len / 4;
+		err = nl80211_validate_rssi_tholds(sta_mon_config.rssi_tholds,
+						   sta_mon_config.n_rssi_tholds);
+		if (err)
+			return err;
+
+		return rdev_set_sta_mon_rssi_config(rdev, dev, addr,
+						    &sta_mon_config);
+	}
+
+	return -EINVAL;
+}
+
 #define NL80211_FLAG_NEED_WIPHY		0x01
 #define NL80211_FLAG_NEED_NETDEV	0x02
 #define NL80211_FLAG_NEED_RTNL		0x04
@@ -14187,6 +14258,14 @@ static void nl80211_post_doit(const struct genl_ops *ops, struct sk_buff *skb,
 		.internal_flags = NL80211_FLAG_NEED_NETDEV_UP |
 				  NL80211_FLAG_NEED_RTNL,
 	},
+	{
+		.cmd = NL80211_CMD_SET_STA_MON,
+		.doit = nl80211_set_sta_mon,
+		.policy = nl80211_policy,
+		.flags = GENL_UNS_ADMIN_PERM,
+		.internal_flags = NL80211_FLAG_NEED_NETDEV_UP |
+				  NL80211_FLAG_NEED_RTNL,
+	},
 };
 
 static struct genl_family nl80211_fam __ro_after_init = {
@@ -15381,7 +15460,8 @@ bool cfg80211_rx_control_port(struct net_device *dev,
 EXPORT_SYMBOL(cfg80211_rx_control_port);
 
 static struct sk_buff *cfg80211_prepare_cqm(struct net_device *dev,
-					    const char *mac, gfp_t gfp)
+					    const char *mac, gfp_t gfp,
+					    enum nl80211_commands cmd)
 {
 	struct wireless_dev *wdev = dev->ieee80211_ptr;
 	struct cfg80211_registered_device *rdev = wiphy_to_rdev(wdev->wiphy);
@@ -15393,7 +15473,7 @@ static struct sk_buff *cfg80211_prepare_cqm(struct net_device *dev,
 
 	cb = (void **)msg->cb;
 
-	cb[0] = nl80211hdr_put(msg, 0, 0, 0, NL80211_CMD_NOTIFY_CQM);
+	cb[0] = nl80211hdr_put(msg, 0, 0, 0, cmd);
 	if (!cb[0]) {
 		nlmsg_free(msg);
 		return NULL;
@@ -15455,7 +15535,7 @@ void cfg80211_cqm_rssi_notify(struct net_device *dev,
 			rssi_level = wdev->cqm_config->last_rssi_event_value;
 	}
 
-	msg = cfg80211_prepare_cqm(dev, NULL, gfp);
+	msg = cfg80211_prepare_cqm(dev, NULL, gfp, NL80211_CMD_NOTIFY_CQM);
 	if (!msg)
 		return;
 
@@ -15476,13 +15556,48 @@ void cfg80211_cqm_rssi_notify(struct net_device *dev,
 }
 EXPORT_SYMBOL(cfg80211_cqm_rssi_notify);
 
+void
+cfg80211_sta_mon_rssi_notify(struct net_device *dev, const u8 *peer,
+			     enum nl80211_cqm_rssi_threshold_event rssi_event,
+			     s32 rssi_level, gfp_t gfp)
+{
+	struct sk_buff *msg;
+
+	trace_cfg80211_sta_mon_rssi_notify(dev, peer, rssi_event, rssi_level);
+	if (WARN_ON(!peer))
+		return;
+
+	if (WARN_ON(rssi_event != NL80211_CQM_RSSI_THRESHOLD_EVENT_LOW &&
+		    rssi_event != NL80211_CQM_RSSI_THRESHOLD_EVENT_HIGH))
+		return;
+
+	msg = cfg80211_prepare_cqm(dev, peer, gfp, NL80211_CMD_NOTIFY_STA_MON);
+	if (!msg)
+		return;
+
+	if (nla_put_u32(msg, NL80211_ATTR_CQM_RSSI_THRESHOLD_EVENT,
+			rssi_event))
+		goto nla_put_failure;
+
+	if (rssi_level && nla_put_s32(msg, NL80211_ATTR_CQM_RSSI_LEVEL,
+				      rssi_level))
+		goto nla_put_failure;
+
+	cfg80211_send_cqm(msg, gfp);
+	return;
+
+ nla_put_failure:
+	nlmsg_free(msg);
+}
+EXPORT_SYMBOL(cfg80211_sta_mon_rssi_notify);
+
 void cfg80211_cqm_txe_notify(struct net_device *dev,
 			     const u8 *peer, u32 num_packets,
 			     u32 rate, u32 intvl, gfp_t gfp)
 {
 	struct sk_buff *msg;
 
-	msg = cfg80211_prepare_cqm(dev, peer, gfp);
+	msg = cfg80211_prepare_cqm(dev, peer, gfp, NL80211_CMD_NOTIFY_CQM);
 	if (!msg)
 		return;
 
@@ -15510,7 +15625,7 @@ void cfg80211_cqm_pktloss_notify(struct net_device *dev,
 
 	trace_cfg80211_cqm_pktloss_notify(dev, peer, num_packets);
 
-	msg = cfg80211_prepare_cqm(dev, peer, gfp);
+	msg = cfg80211_prepare_cqm(dev, peer, gfp, NL80211_CMD_NOTIFY_CQM);
 	if (!msg)
 		return;
 
@@ -15529,7 +15644,7 @@ void cfg80211_cqm_beacon_loss_notify(struct net_device *dev, gfp_t gfp)
 {
 	struct sk_buff *msg;
 
-	msg = cfg80211_prepare_cqm(dev, NULL, gfp);
+	msg = cfg80211_prepare_cqm(dev, NULL, gfp, NL80211_CMD_NOTIFY_CQM);
 	if (!msg)
 		return;
 
diff --git a/net/wireless/rdev-ops.h b/net/wireless/rdev-ops.h
index 5cb48d1..aec2811 100644
--- a/net/wireless/rdev-ops.h
+++ b/net/wireless/rdev-ops.h
@@ -1272,4 +1272,17 @@ static inline int rdev_del_pmk(struct cfg80211_registered_device *rdev,
 	trace_rdev_return_void(&rdev->wiphy);
 }
 
+static inline int
+rdev_set_sta_mon_rssi_config(struct cfg80211_registered_device *rdev,
+			     struct net_device *dev, const u8 *addr,
+			     const struct cfg80211_sta_mon *sta_mon_config)
+{
+	int ret = -EOPNOTSUPP;
+
+	ret = rdev->ops->set_sta_mon_rssi_config(&rdev->wiphy, dev,
+						 addr, sta_mon_config);
+	trace_rdev_return_int(&rdev->wiphy, ret);
+	return ret;
+}
+
 #endif /* __CFG80211_RDEV_OPS */
diff --git a/net/wireless/trace.h b/net/wireless/trace.h
index 44b2ce1..48b81e5 100644
--- a/net/wireless/trace.h
+++ b/net/wireless/trace.h
@@ -3362,6 +3362,28 @@
 		  WIPHY_PR_ARG, WDEV_PR_ARG,
 		  (unsigned long long)__entry->cookie)
 );
+
+TRACE_EVENT(cfg80211_sta_mon_rssi_notify,
+	TP_PROTO(struct net_device *netdev, const u8 *addr,
+		 enum nl80211_cqm_rssi_threshold_event rssi_event,
+		 s32 rssi_level),
+	TP_ARGS(netdev, addr, rssi_event, rssi_level),
+	TP_STRUCT__entry(
+		NETDEV_ENTRY
+		MAC_ENTRY(addr)
+		__field(enum nl80211_cqm_rssi_threshold_event, rssi_event)
+		__field(s32, rssi_level)
+	),
+	TP_fast_assign(
+		NETDEV_ASSIGN;
+		MAC_ASSIGN(addr, addr);
+		__entry->rssi_event = rssi_event;
+		__entry->rssi_level = rssi_level;
+	),
+	TP_printk(NETDEV_PR_FMT ", station mac: " MAC_PR_FMT
+		  ", rssi event: %d, level: %d", NETDEV_PR_ARG,
+		  MAC_PR_ARG(addr), __entry->rssi_event, __entry->rssi_level)
+);
 #endif /* !__RDEV_OPS_TRACE || TRACE_HEADER_MULTI_READ */
 
 #undef TRACE_INCLUDE_PATH
-- 
1.7.9.5