wifi: mac80211: use wiphy_hrtimer_work for csa.switch_work

The work item may be scheduled relatively far in the future. As the
event happens at a specific point in time, the normal timer accuracy is
not sufficient in that case.

Switch to use wiphy_hrtimer_work so that the accuracy is sufficient. To
make this work, use the same clock to store the timestamp.

CC: [e-mail]
Fixes: ec3252bff7b6 ("wifi: mac80211: use wiphy work for channel switch")
Signed-off-by: Benjamin Berg <[e-mail]>
Reviewed-by: Johannes Berg <[e-mail]>
Signed-off-by: Miri Korenblit <[e-mail]>
Link: https://patch.msgid.link/20251028125710.68258c7e4ac4.I4ff2b2cdffbbf858bf5f08baccc7a88c4f9efe6f@changeid
Signed-off-by: Johannes Berg <[e-mail]>

net/mac80211/chan.c

···
 				 &link->csa.finalize_work);
 		break;
 	case NL80211_IFTYPE_STATION:
-		wiphy_delayed_work_queue(sdata->local->hw.wiphy,
+		wiphy_hrtimer_work_queue(sdata->local->hw.wiphy,
 					 &link->u.mgd.csa.switch_work, 0);
 		break;
 	case NL80211_IFTYPE_UNSPECIFIED:

net/mac80211/ieee80211_i.h

···
 	bool operating_11g_mode;
 
 	struct {
-		struct wiphy_delayed_work switch_work;
+		struct wiphy_hrtimer_work switch_work;
 		struct cfg80211_chan_def ap_chandef;
 		struct ieee80211_parsed_tpe tpe;
-		unsigned long time;
+		ktime_t time;
 		bool waiting_bcn;
 		bool ignored_same_chan;
 		bool blocked_tx;

net/mac80211/link.c

···
 		 * from there.
 		 */
 		if (link->conf->csa_active)
-			wiphy_delayed_work_queue(local->hw.wiphy,
+			wiphy_hrtimer_work_queue(local->hw.wiphy,
 						 &link->u.mgd.csa.switch_work,
 						 link->u.mgd.csa.time -
-						 jiffies);
+						 ktime_get_boottime());
 	}
 
 	for_each_set_bit(link_id, &add, IEEE80211_MLD_MAX_NUM_LINKS) {

net/mac80211/mlme.c

···
 			return;
 		}
 
-		wiphy_delayed_work_queue(sdata->local->hw.wiphy,
+		wiphy_hrtimer_work_queue(sdata->local->hw.wiphy,
 					 &link->u.mgd.csa.switch_work, 0);
 	}
 
···
 		.timestamp = timestamp,
 		.device_timestamp = device_timestamp,
 	};
-	unsigned long now;
+	u32 csa_time_tu;
+	ktime_t now;
 	int res;
 
 	lockdep_assert_wiphy(local->hw.wiphy);
···
 					  csa_ie.mode);
 
 	/* we may have to handle timeout for deactivated link in software */
-	now = jiffies;
-	link->u.mgd.csa.time = now +
-			       TU_TO_JIFFIES((max_t(int, csa_ie.count, 1) - 1) *
-					     link->conf->beacon_int);
+	now = ktime_get_boottime();
+	csa_time_tu = (max_t(int, csa_ie.count, 1) - 1) * link->conf->beacon_int;
+	link->u.mgd.csa.time = now + us_to_ktime(ieee80211_tu_to_usec(csa_time_tu));
 
 	if (ieee80211_vif_link_active(&sdata->vif, link->link_id) &&
 	    local->ops->channel_switch) {
···
 	}
 
 	/* channel switch handled in software */
-	wiphy_delayed_work_queue(local->hw.wiphy,
+	wiphy_hrtimer_work_queue(local->hw.wiphy,
 				 &link->u.mgd.csa.switch_work,
 				 link->u.mgd.csa.time - now);
 	return;
···
 	else
 		link->u.mgd.req_smps = IEEE80211_SMPS_OFF;
 
-	wiphy_delayed_work_init(&link->u.mgd.csa.switch_work,
+	wiphy_hrtimer_work_init(&link->u.mgd.csa.switch_work,
 				ieee80211_csa_switch_work);
 
 	ieee80211_clear_tpe(&link->conf->tpe);
···
 			  &link->u.mgd.request_smps_work);
 	wiphy_work_cancel(link->sdata->local->hw.wiphy,
 			  &link->u.mgd.recalc_smps);
-	wiphy_delayed_work_cancel(link->sdata->local->hw.wiphy,
+	wiphy_hrtimer_work_cancel(link->sdata->local->hw.wiphy,
 				  &link->u.mgd.csa.switch_work);
 }