Break out the current 802.11 software scan methods into an indirect table.

In order for drivers to provide an alternate set of scan methods,
these have to finally use an indirection table and all of the calls
in ieee80211_scan.c need to use said table.

For all existing drivers - this is basically a glorified, KBI-breaking
functional no-op.

This is also not the final form - too much functionality is currently
hiding in ieee80211_scan_sw.c that should be in ieee80211_scan.c.
That'll be the target of some follow-up commits.

Note:

* You have to recompile your kernel/drivers after this - the net80211 KBI has
  changed.
* I'm not yet planning on bumping any versioning - I have a few more things
  to shuffle around.

Tested:

* urtwn(4) - STA mode
* Intel 7260 in local repo - overriding the methods and table at
  attach time has the desired effect (ie, all the methods are called,
  but nothing is ever performed.)

sys/net80211/ieee80211_scan.c

@@ -71,15 +71,14 @@ __FBSDID("$FreeBSD$");
 void
 ieee80211_scan_attach(struct ieee80211com *ic)
 {
-
 	/*
-	 * For now, the swscan module does both the
+	 * If there's no scan method pointer, attach the
-	 * allocation (so it can pad it) and sets up the net80211
+	 * swscan set as a default.
-	 * bits.
-	 *
-	 * I'll split this stuff later.
 	 */
+	if (ic->ic_scan_methods == NULL)
 		ieee80211_swscan_attach(ic);
+	else
+		ic->ic_scan_methods->sc_attach(ic);
 }
 
 void
@@ -88,12 +87,11 @@ ieee80211_scan_detach(struct ieee80211com *ic)
 
 	/*
 	 * Ideally we'd do the ss_ops detach call here;
-	 * but then ieee80211_swscan_detach would need
+	 * but then sc_detach() would need to be split in two.
-	 * to be split in two.
 	 *
 	 * I'll do that later.
 	 */
-	ieee80211_swscan_detach(ic);
+	ic->ic_scan_methods->sc_detach(ic);
 }
 
 static const struct ieee80211_roamparam defroam[IEEE80211_MODE_MAX] = {
@@ -122,6 +120,8 @@ static const struct ieee80211_roamparam defroam[IEEE80211_MODE_MAX] = {
 void
 ieee80211_scan_vattach(struct ieee80211vap *vap)
 {
+	struct ieee80211com *ic = vap->iv_ic;
+
 	vap->iv_bgscanidle = (IEEE80211_BGSCAN_IDLE_DEFAULT*1000)/hz;
 	vap->iv_bgscanintvl = IEEE80211_BGSCAN_INTVAL_DEFAULT*hz;
 	vap->iv_scanvalid = IEEE80211_SCAN_VALID_DEFAULT*hz;
@@ -129,7 +129,7 @@ ieee80211_scan_vattach(struct ieee80211vap *vap)
 	vap->iv_roaming = IEEE80211_ROAMING_AUTO;
 	memcpy(vap->iv_roamparms, defroam, sizeof(defroam));
 
-	ieee80211_swscan_vattach(vap);
+	ic->ic_scan_methods->sc_vattach(vap);
 }
 
 void
@@ -141,7 +141,7 @@ ieee80211_scan_vdetach(struct ieee80211vap *vap)
 	IEEE80211_LOCK(ic);
 	ss = ic->ic_scan;
 
-	ieee80211_swscan_vdetach(vap);
+	ic->ic_scan_methods->sc_vdetach(vap);
 
 	if (ss != NULL && ss->ss_vap == vap) {
 		if (ss->ss_ops != NULL) {
@@ -314,6 +314,7 @@ ieee80211_start_scan(struct ieee80211vap *vap, int flags,
 	u_int nssid, const struct ieee80211_scan_ssid ssids[])
 {
 	const struct ieee80211_scanner *scan;
+	struct ieee80211com *ic = vap->iv_ic;
 
 	scan = ieee80211_scanner_get(vap->iv_opmode);
 	if (scan == NULL) {
@@ -324,8 +325,7 @@ ieee80211_start_scan(struct ieee80211vap *vap, int flags,
 		return 0;
 	}
 
-	/* XXX ops */
+	return ic->ic_scan_methods->sc_start_scan(scan, vap, flags, duration,
-	return ieee80211_swscan_start_scan(scan, vap, flags, duration,
 	    mindwell, maxdwell, nssid, ssids);
 }
 
@@ -376,11 +376,10 @@ ieee80211_check_scan(struct ieee80211vap *vap, int flags,
 
 	/*
 	 * XXX TODO: separate things out a bit better.
-	 * XXX TODO: ops
 	 */
 	ieee80211_scan_update_locked(vap, scan);
 
-	result = ieee80211_swscan_check_scan(scan, vap, flags, duration,
+	result = ic->ic_scan_methods->sc_check_scan(scan, vap, flags, duration,
 	    mindwell, maxdwell, nssid, ssids);
 
 	IEEE80211_UNLOCK(ic);
@@ -408,6 +407,7 @@ ieee80211_check_scan_current(struct ieee80211vap *vap)
 int
 ieee80211_bg_scan(struct ieee80211vap *vap, int flags)
 {
+	struct ieee80211com *ic = vap->iv_ic;
 	const struct ieee80211_scanner *scan;
 
 	// IEEE80211_UNLOCK_ASSERT(sc);
@@ -425,10 +425,8 @@ ieee80211_bg_scan(struct ieee80211vap *vap, int flags)
 	 * XXX TODO: pull apart the bgscan logic into whatever
 	 * belongs here and whatever belongs in the software
 	 * scanner.
-	 *
-	 * XXX TODO: ops
 	 */
-	return (ieee80211_swscan_bg_scan(scan, vap, flags));
+	return (ic->ic_scan_methods->sc_bg_scan(scan, vap, flags));
 }
 
 /*
@@ -437,9 +435,9 @@ ieee80211_bg_scan(struct ieee80211vap *vap, int flags)
 void
 ieee80211_cancel_scan(struct ieee80211vap *vap)
 {
+	struct ieee80211com *ic = vap->iv_ic;
 
-	/* XXX TODO: ops */
+	ic->ic_scan_methods->sc_cancel_scan(vap);
-	ieee80211_swscan_cancel_scan(vap);
 }
 
 /*
@@ -448,9 +446,9 @@ ieee80211_cancel_scan(struct ieee80211vap *vap)
 void
 ieee80211_cancel_anyscan(struct ieee80211vap *vap)
 {
+	struct ieee80211com *ic = vap->iv_ic;
 
-	/* XXX TODO: ops */
+	ic->ic_scan_methods->sc_cancel_anyscan(vap);
-	ieee80211_swscan_cancel_anyscan(vap);
 }
 
 /*
@@ -460,9 +458,9 @@ ieee80211_cancel_anyscan(struct ieee80211vap *vap)
 void
 ieee80211_scan_next(struct ieee80211vap *vap)
 {
+	struct ieee80211com *ic = vap->iv_ic;
 
-	/* XXX TODO: ops */
+	ic->ic_scan_methods->sc_scan_next(vap);
-	ieee80211_swscan_scan_next(vap);
 }
 
 /*
@@ -481,8 +479,7 @@ ieee80211_scan_done(struct ieee80211vap *vap)
 	ss = ic->ic_scan;
 	ss->ss_next = ss->ss_last; /* all channels are complete */
 
-	/* XXX TODO: ops */
+	ic->ic_scan_methods->sc_scan_done(vap);
-	ieee80211_swscan_scan_done(vap);
 
 	IEEE80211_UNLOCK(ic);
 }
@@ -504,8 +501,7 @@ ieee80211_probe_curchan(struct ieee80211vap *vap, int force)
 		return;
 	}
 
-	/* XXX TODO: ops */
+	ic->ic_scan_methods->sc_scan_probe_curchan(vap, force);
-	ieee80211_swscan_probe_curchan(vap, force);
 }
 
 #ifdef IEEE80211_DEBUG
@@ -567,8 +563,9 @@ ieee80211_add_scan(struct ieee80211vap *vap,
 	const struct ieee80211_frame *wh,
 	int subtype, int rssi, int noise)
 {
+	struct ieee80211com *ic = vap->iv_ic;
 
-	return (ieee80211_swscan_add_scan(vap, curchan, sp, wh, subtype,
+	return (ic->ic_scan_methods->sc_add_scan(vap, curchan, sp, wh, subtype,
 	    rssi, noise));
 }
 

sys/net80211/ieee80211_scan.h

@@ -79,6 +79,39 @@ struct ieee80211_scan_ssid {
 };
 #define	IEEE80211_SCAN_MAX_SSID	1		/* max # ssid's to probe */
 
+/*
+ * High-level implementation visible to ieee80211_scan.[ch].
+ *
+ * The default scanner (ieee80211_scan_sw.[ch]) implements a software
+ * driven scanner.  Firmware driven scanning needs a different set of
+ * behaviours.
+ */
+struct ieee80211_scan_methods {
+	void (*sc_attach)(struct ieee80211com *);
+	void (*sc_detach)(struct ieee80211com *);
+	void (*sc_vattach)(struct ieee80211vap *);
+	void (*sc_vdetach)(struct ieee80211vap *);
+	void (*sc_set_scan_duration)(struct ieee80211vap *, u_int);
+	int (*sc_start_scan)(const struct ieee80211_scanner *,
+	    struct ieee80211vap *, int, u_int, u_int, u_int, u_int,
+	    const struct ieee80211_scan_ssid ssids[]);
+	int (*sc_check_scan)(const struct ieee80211_scanner *,
+	    struct ieee80211vap *, int, u_int, u_int, u_int, u_int,
+	    const struct ieee80211_scan_ssid ssids[]);
+	int (*sc_bg_scan)(const struct ieee80211_scanner *,
+	    struct ieee80211vap *, int);
+	void (*sc_cancel_scan)(struct ieee80211vap *);
+	void (*sc_cancel_anyscan)(struct ieee80211vap *);
+	void (*sc_scan_next)(struct ieee80211vap *);
+	void (*sc_scan_done)(struct ieee80211vap *);
+	void (*sc_scan_probe_curchan)(struct ieee80211vap *, int);
+	void (*sc_add_scan)(struct ieee80211vap *,
+	    struct ieee80211_channel *,
+	    const struct ieee80211_scanparams *,
+	    const struct ieee80211_frame *,
+	    int, int, int);
+};
+
 /*
  * Scan state visible to the 802.11 layer.  Scan parameters and
  * results are stored in this data structure.  The ieee80211_scan_state

sys/net80211/ieee80211_scan_sw.c

@@ -102,33 +102,7 @@ static	void scan_task(void *, int);
 
 MALLOC_DEFINE(M_80211_SCAN, "80211scan", "802.11 scan state");
 
-void
+static void
-ieee80211_swscan_attach(struct ieee80211com *ic)
-{
-	struct scan_state *ss;
-
-	ss = (struct scan_state *) IEEE80211_MALLOC(sizeof(struct scan_state),
-		M_80211_SCAN, IEEE80211_M_NOWAIT | IEEE80211_M_ZERO);
-	if (ss == NULL) {
-		ic->ic_scan = NULL;
-		return;
-	}
-	callout_init_mtx(&ss->ss_scan_timer, IEEE80211_LOCK_OBJ(ic), 0);
-	cv_init(&ss->ss_scan_cv, "scan");
-	TASK_INIT(&ss->ss_scan_task, 0, scan_task, ss);
-
-	ic->ic_scan = &ss->base;
-	ss->base.ss_ic = ic;
-
-	ic->ic_scan_curchan = scan_curchan;
-	ic->ic_scan_mindwell = scan_mindwell;
-
-	/*
-	 * TODO: all of the non-vap scan calls should be methods!
-	 */
-}
-
-void
 ieee80211_swscan_detach(struct ieee80211com *ic)
 {
 	struct ieee80211_scan_state *ss = ic->ic_scan;
@@ -159,7 +133,7 @@ ieee80211_swscan_detach(struct ieee80211com *ic)
 	}
 }
 
-void
+static void
 ieee80211_swscan_vattach(struct ieee80211vap *vap)
 {
 	/* nothing to do for now */
@@ -169,7 +143,7 @@ ieee80211_swscan_vattach(struct ieee80211vap *vap)
 
 }
 
-void
+static void
 ieee80211_swscan_vdetach(struct ieee80211vap *vap)
 {
 	struct ieee80211com *ic = vap->iv_ic;
@@ -185,7 +159,7 @@ ieee80211_swscan_vdetach(struct ieee80211vap *vap)
 	}
 }
 
-void
+static void
 ieee80211_swscan_set_scan_duration(struct ieee80211vap *vap, u_int duration)
 {
 	struct ieee80211com *ic = vap->iv_ic;
@@ -278,7 +252,7 @@ ieee80211_swscan_start_scan_locked(const struct ieee80211_scanner *scan,
  *
  * Called without the comlock held; grab the comlock as appropriate.
  */
-int
+static int
 ieee80211_swscan_start_scan(const struct ieee80211_scanner *scan,
     struct ieee80211vap *vap, int flags,
     u_int duration, u_int mindwell, u_int maxdwell,
@@ -305,7 +279,7 @@ ieee80211_swscan_start_scan(const struct ieee80211_scanner *scan,
  *
  * XXX TODO: split out!
  */
-int
+static int
 ieee80211_swscan_check_scan(const struct ieee80211_scanner *scan,
     struct ieee80211vap *vap, int flags,
     u_int duration, u_int mindwell, u_int maxdwell,
@@ -363,7 +337,7 @@ ieee80211_swscan_check_scan(const struct ieee80211_scanner *scan,
  * Restart a previous scan.  If the previous scan completed
  * then we start again using the existing channel list.
  */
-int
+static int
 ieee80211_swscan_bg_scan(const struct ieee80211_scanner *scan,
     struct ieee80211vap *vap, int flags)
 {
@@ -454,7 +428,7 @@ ieee80211_swscan_bg_scan(const struct ieee80211_scanner *scan,
 /*
  * Cancel any scan currently going on for the specified vap.
  */
-void
+static void
 ieee80211_swscan_cancel_scan(struct ieee80211vap *vap)
 {
 	struct ieee80211com *ic = vap->iv_ic;
@@ -488,7 +462,7 @@ ieee80211_swscan_cancel_scan(struct ieee80211vap *vap)
 /*
  * Cancel any scan currently going on.
  */
-void
+static void
 ieee80211_swscan_cancel_anyscan(struct ieee80211vap *vap)
 {
 	struct ieee80211com *ic = vap->iv_ic;
@@ -522,7 +496,7 @@ ieee80211_swscan_cancel_anyscan(struct ieee80211vap *vap)
  * Public access to scan_next for drivers that manage
  * scanning themselves (e.g. for firmware-based devices).
  */
-void
+static void
 ieee80211_swscan_scan_next(struct ieee80211vap *vap)
 {
 	struct ieee80211com *ic = vap->iv_ic;
@@ -540,7 +514,7 @@ ieee80211_swscan_scan_next(struct ieee80211vap *vap)
  * Public access to scan_next for drivers that are not able to scan single
  * channels (e.g. for firmware-based devices).
  */
-void
+static void
 ieee80211_swscan_scan_done(struct ieee80211vap *vap)
 {
 	struct ieee80211com *ic = vap->iv_ic;
@@ -559,7 +533,7 @@ ieee80211_swscan_scan_done(struct ieee80211vap *vap)
  * listen for beacons on the channel; if we receive something
  * then we'll transmit a probe request.
  */
-void
+static void
 ieee80211_swscan_probe_curchan(struct ieee80211vap *vap, int force)
 {
 	struct ieee80211com *ic = vap->iv_ic;
@@ -887,7 +861,7 @@ scan_task(void *arg, int pending)
 /*
  * Process a beacon or probe response frame.
  */
-void
+static void
 ieee80211_swscan_add_scan(struct ieee80211vap *vap,
 	struct ieee80211_channel *curchan,
 	const struct ieee80211_scanparams *sp,
@@ -935,3 +909,50 @@ ieee80211_swscan_add_scan(struct ieee80211vap *vap,
 	}
 }
 
+static struct ieee80211_scan_methods swscan_methods = {
+	.sc_attach = ieee80211_swscan_attach,
+	.sc_detach = ieee80211_swscan_detach,
+	.sc_vattach = ieee80211_swscan_vattach,
+	.sc_vdetach = ieee80211_swscan_vdetach,
+	.sc_set_scan_duration = ieee80211_swscan_set_scan_duration,
+	.sc_start_scan = ieee80211_swscan_start_scan,
+	.sc_check_scan = ieee80211_swscan_check_scan,
+	.sc_bg_scan = ieee80211_swscan_bg_scan,
+	.sc_cancel_scan = ieee80211_swscan_cancel_scan,
+	.sc_cancel_anyscan = ieee80211_swscan_cancel_anyscan,
+	.sc_scan_next = ieee80211_swscan_scan_next,
+	.sc_scan_done = ieee80211_swscan_scan_done,
+	.sc_scan_probe_curchan = ieee80211_swscan_probe_curchan,
+	.sc_add_scan = ieee80211_swscan_add_scan
+};
+
+/*
+ * Default scan attach method.
+ */
+void
+ieee80211_swscan_attach(struct ieee80211com *ic)
+{
+	struct scan_state *ss;
+
+	/*
+	 * Setup the default methods
+	 */
+	ic->ic_scan_methods = &swscan_methods;
+
+	/* Allocate initial scan state */
+	ss = (struct scan_state *) IEEE80211_MALLOC(sizeof(struct scan_state),
+		M_80211_SCAN, IEEE80211_M_NOWAIT | IEEE80211_M_ZERO);
+	if (ss == NULL) {
+		ic->ic_scan = NULL;
+		return;
+	}
+	callout_init_mtx(&ss->ss_scan_timer, IEEE80211_LOCK_OBJ(ic), 0);
+	cv_init(&ss->ss_scan_cv, "scan");
+	TASK_INIT(&ss->ss_scan_task, 0, scan_task, ss);
+
+	ic->ic_scan = &ss->base;
+	ss->base.ss_ic = ic;
+
+	ic->ic_scan_curchan = scan_curchan;
+	ic->ic_scan_mindwell = scan_mindwell;
+}

sys/net80211/ieee80211_scan_sw.h

@@ -28,34 +28,5 @@
 #define	__NET80211_IEEE80211_SCAN_SW_H__
 
 extern	void ieee80211_swscan_attach(struct ieee80211com *ic);
-extern	void ieee80211_swscan_detach(struct ieee80211com *ic);
-
-extern	void ieee80211_swscan_vattach(struct ieee80211vap *vap);
-extern	void ieee80211_swscan_vdetach(struct ieee80211vap *vap);
-
-extern	int ieee80211_swscan_start_scan(const struct ieee80211_scanner *scan,
-	    struct ieee80211vap *vap, int flags,
-	    u_int duration, u_int mindwell, u_int maxdwell,
-	    u_int nssid, const struct ieee80211_scan_ssid ssids[]);
-extern	void ieee80211_swscan_set_scan_duration(struct ieee80211vap *vap,
-	    u_int duration);
-extern	void ieee80211_swscan_run_scan_task(struct ieee80211vap *vap);
-extern	int ieee80211_swscan_check_scan(const struct ieee80211_scanner *scan,
-	    struct ieee80211vap *vap, int flags,
-	    u_int duration, u_int mindwell, u_int maxdwell,
-	    u_int nssid, const struct ieee80211_scan_ssid ssids[]);
-extern	int ieee80211_swscan_bg_scan(const struct ieee80211_scanner *scan,
-	    struct ieee80211vap *vap, int flags);
-extern	void ieee80211_swscan_cancel_scan(struct ieee80211vap *vap);
-extern	void ieee80211_swscan_cancel_anyscan(struct ieee80211vap *vap);
-extern	void ieee80211_swscan_scan_next(struct ieee80211vap *vap);
-extern	void ieee80211_swscan_scan_done(struct ieee80211vap *vap);
-extern	void ieee80211_swscan_probe_curchan(struct ieee80211vap *vap,
-	    int force);
-extern	void ieee80211_swscan_add_scan(struct ieee80211vap *vap,
-	    struct ieee80211_channel *curchan,
-	    const struct ieee80211_scanparams *sp,
-	    const struct ieee80211_frame *wh,
-	    int subtype, int rssi, int noise);
 
 #endif	/* __NET80211_IEEE80211_SCAN_SW_H__ */

sys/net80211/ieee80211_var.h

@@ -197,6 +197,7 @@ struct ieee80211com {
 	struct ieee80211_dfs_state ic_dfs;	/* DFS state */
 
 	struct ieee80211_scan_state *ic_scan;	/* scan state */
+	struct ieee80211_scan_methods *ic_scan_methods;	/* scan methods */
 	int			ic_lastdata;	/* time of last data frame */
 	int			ic_lastscan;	/* time last scan completed */