[PATCH wireless-next v4 1/3] wifi: cfg80211: add support to handle incumbent signal detected event from mac80211/driver

[Amith A <amith.a@oss.qualcomm.com>]

From: Hari Chandrakanthan <quic_haric@quicinc.com>

When any incumbent signal is detected by an AP/mesh interface operating
in 6 GHz band, FCC mandates the AP/mesh to vacate the channels affected
by it [1].

Add a new API cfg80211_incumbent_signal_detect_event() that can be used
by mac80211 (or full mac drivers) to notify the higher layers about the
signal interference event with the interference bitmap in which each bit
denotes the affected 20 MHz in the operating channel.

Add support for the new nl80211 event and nl80211 attribute as well to
notify userspace on the details about the interference event. Userspace is
expected to process it and take further action - vacate the channel, or
reduce the bandwidth.

[1] - https://apps.fcc.gov/kdb/GetAttachment.html?id=nXQiRC%2B4mfiA54Zha%2BrW4Q%3D%3D&desc=987594%20D02%20U-NII%206%20GHz%20EMC%20Measurement%20v03&tracking_number=277034

Signed-off-by: Hari Chandrakanthan <quic_haric@quicinc.com>
Signed-off-by: Amith A <amith.a@oss.qualcomm.com>
---
 include/net/cfg80211.h       | 23 +++++++++++++++++++++
 include/uapi/linux/nl80211.h | 19 +++++++++++++++++
 net/wireless/nl80211.c       | 40 ++++++++++++++++++++++++++++++++++++
 net/wireless/trace.h         | 19 +++++++++++++++++
 4 files changed, 101 insertions(+)

diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index 0ae0aa7594a3..91c85a896fd6 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -10423,4 +10423,27 @@ cfg80211_s1g_get_primary_sibling(struct wiphy *wiphy,
 	return ieee80211_get_channel_khz(wiphy, sibling_1mhz_khz);
 }
 
+
+/**
+ * cfg80211_incumbent_signal_notify - Notify userspace of incumbent signal detection
+ * @wiphy: the wiphy to use
+ * @chandef: channel definition in which the interference was detected
+ * @signal_interference_bitmap: bitmap indicating interference across 20 MHz segments
+ * @gfp: allocation context for message creation and multicast; pass GFP_ATOMIC
+ *	if called from atomic context (e.g. firmware event handler), otherwise
+ *	GFP_KERNEL
+ *
+ * Use this function to notify userspace when an incumbent signal is detected on
+ * the operating channel in the 6 GHz band. The notification includes the
+ * current channel definition and a bitmap representing interference across
+ * the operating bandwidth. Each bit in the bitmap corresponds to a 20 MHz
+ * segment, with the lowest bit representing the lowest frequency segment.
+ * Punctured sub-channels are included in the bitmap structure but are always
+ * set to zero since interference detection is not performed on them.
+ */
+void cfg80211_incumbent_signal_notify(struct wiphy *wiphy,
+				      struct cfg80211_chan_def *chandef,
+				      u32 signal_interference_bitmap,
+				      gfp_t gfp);
+
 #endif /* __NET_CFG80211_H */
diff --git a/include/uapi/linux/nl80211.h b/include/uapi/linux/nl80211.h
index 54ddbd9a5459..0bda5c05b47a 100644
--- a/include/uapi/linux/nl80211.h
+++ b/include/uapi/linux/nl80211.h
@@ -1361,6 +1361,12 @@
  *	user space that the NAN new cluster has been joined. The cluster ID is
  *	indicated by %NL80211_ATTR_MAC.
  *
+ * @NL80211_CMD_INCUMBENT_SIGNAL_DETECT: Once any incumbent signal is detected
+ *	on the operating channel in 6 GHz band, userspace is notified with the
+ *	signal interference bitmap using
+ *	%NL80211_ATTR_INCUMBENT_SIGNAL_INTERFERENCE_BITMAP. The current channel
+ *	definition is also sent.
+ *
  * @NL80211_CMD_MAX: highest used command number
  * @__NL80211_CMD_AFTER_LAST: internal use
  */
@@ -1624,6 +1630,8 @@ enum nl80211_commands {
 	NL80211_CMD_NAN_NEXT_DW_NOTIFICATION,
 	NL80211_CMD_NAN_CLUSTER_JOINED,
 
+	NL80211_CMD_INCUMBENT_SIGNAL_DETECT,
+
 	/* add new commands above here */
 
 	/* used to define NL80211_CMD_MAX below */
@@ -2976,6 +2984,15 @@ enum nl80211_commands {
  * @NL80211_ATTR_EPP_PEER: A flag attribute to indicate if the peer is an EPP
  *	STA. Used with %NL80211_CMD_NEW_STA and %NL80211_CMD_ADD_LINK_STA
  *
+ * @NL80211_ATTR_INCUMBENT_SIGNAL_INTERFERENCE_BITMAP: u32 attribute specifying
+ *	the signal interference bitmap detected on the operating bandwidth for
+ *	%NL80211_CMD_INCUMBENT_SIGNAL_DETECT. Each bit represents a 20 MHz
+ *	segment, lowest bit corresponds to the lowest 20 MHz segment, in the
+ *	operating bandwidth where the interference is detected. Punctured
+ *	sub-channels are included in the bitmap structure; however, since
+ *	interference detection is not performed on these sub-channels, their
+ *	corresponding bits are consistently set to zero.
+ *
  * @NUM_NL80211_ATTR: total number of nl80211_attrs available
  * @NL80211_ATTR_MAX: highest attribute number currently defined
  * @__NL80211_ATTR_AFTER_LAST: internal use
@@ -3546,6 +3563,8 @@ enum nl80211_attrs {
 
 	NL80211_ATTR_EPP_PEER,
 
+	NL80211_ATTR_INCUMBENT_SIGNAL_INTERFERENCE_BITMAP,
+
 	/* add attributes here, update the policy in nl80211.c */
 
 	__NL80211_ATTR_AFTER_LAST,
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 85e30fda4c46..2b4a84794f8e 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -21045,6 +21045,46 @@ void cfg80211_ch_switch_notify(struct net_device *dev,
 }
 EXPORT_SYMBOL(cfg80211_ch_switch_notify);
 
+void cfg80211_incumbent_signal_notify(struct wiphy *wiphy,
+				      struct cfg80211_chan_def *chandef,
+				      u32 signal_interference_bitmap,
+				      gfp_t gfp)
+{
+	struct cfg80211_registered_device *rdev = wiphy_to_rdev(wiphy);
+	struct sk_buff *msg;
+	void *hdr;
+
+	trace_cfg80211_incumbent_signal_notify(wiphy, chandef, signal_interference_bitmap);
+
+	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, gfp);
+	if (!msg)
+		return;
+
+	hdr = nl80211hdr_put(msg, 0, 0, 0, NL80211_CMD_INCUMBENT_SIGNAL_DETECT);
+	if (!hdr)
+		goto nla_put_failure;
+
+	if (nla_put_u32(msg, NL80211_ATTR_WIPHY, rdev->wiphy_idx))
+		goto nla_put_failure;
+
+	if (nl80211_send_chandef(msg, chandef))
+		goto nla_put_failure;
+
+	if (nla_put_u32(msg, NL80211_ATTR_INCUMBENT_SIGNAL_INTERFERENCE_BITMAP,
+			signal_interference_bitmap))
+		goto nla_put_failure;
+
+	genlmsg_end(msg, hdr);
+
+	genlmsg_multicast_netns(&nl80211_fam, wiphy_net(&rdev->wiphy), msg, 0,
+				NL80211_MCGRP_MLME, gfp);
+	return;
+
+nla_put_failure:
+	nlmsg_free(msg);
+}
+EXPORT_SYMBOL(cfg80211_incumbent_signal_notify);
+
 void cfg80211_ch_switch_started_notify(struct net_device *dev,
 				       struct cfg80211_chan_def *chandef,
 				       unsigned int link_id, u8 count,
diff --git a/net/wireless/trace.h b/net/wireless/trace.h
index 643ccf4f0227..deb283d9e017 100644
--- a/net/wireless/trace.h
+++ b/net/wireless/trace.h
@@ -4225,6 +4225,25 @@ TRACE_EVENT(cfg80211_nan_cluster_joined,
 		  WDEV_PR_ARG, __entry->cluster_id,
 		  __entry->new_cluster ? " [new]" : "")
 );
+
+TRACE_EVENT(cfg80211_incumbent_signal_notify,
+	TP_PROTO(struct wiphy *wiphy,
+		 struct cfg80211_chan_def *chandef,
+		 u32 signal_interference_bitmap),
+	TP_ARGS(wiphy, chandef, signal_interference_bitmap),
+	TP_STRUCT__entry(
+		WIPHY_ENTRY
+		CHAN_DEF_ENTRY
+		__field(u32, signal_interference_bitmap)
+	),
+	TP_fast_assign(
+		WIPHY_ASSIGN;
+		CHAN_DEF_ASSIGN(chandef);
+		__entry->signal_interference_bitmap = signal_interference_bitmap;
+	),
+	TP_printk(WIPHY_PR_FMT ", " CHAN_DEF_PR_FMT ", signal_interference_bitmap=0x%x",
+		  WIPHY_PR_ARG, CHAN_DEF_PR_ARG, __entry->signal_interference_bitmap)
+);
 #endif /* !__RDEV_OPS_TRACE || TRACE_HEADER_MULTI_READ */
 
 #undef TRACE_INCLUDE_PATH
-- 
2.34.1