wl12xx: implement cancel_hw_scan() callback

After implementing cancel_hw_scan(), there is no more need to
flush scan_complete_work on suspend.

scan_complete_work enqueues a new scan_work, that might lead
to the following warning (if the device was already suspended):

WARNING: at drivers/mmc/core/core.c:169 mmc_wait_for_req+0x1ac/0x2c8()
Backtrace:
[<c004b50c>] (dump_backtrace+0x0/0x110)
[<c04fda50>] (dump_stack+0x0/0x1c)
[<c008f700>] (warn_slowpath_common+0x0/0x6c)
[<c008f76c>] (warn_slowpath_null+0x0/0x2c)
[<c034b058>] (mmc_wait_for_req+0x0/0x2c8)
[<c034f804>] (mmc_io_rw_extended+0x0/0x1e4)
[<c0350b5c>] (sdio_io_rw_ext_helper+0x0/0x1ac)
[<c0350e00>] (sdio_memcpy_fromio+0x0/0x2c)
[<bf194464>] (wl1271_sdio_raw_read+0x0/0x1bc [wl12xx_sdio])
[<bf15ac14>] (wl1271_cmd_wait_for_event_or_timeout+0x0/0x19c [wl12xx])
[<bf15adb0>] (wl1271_cmd_wait_for_event+0x0/0x30 [wl12xx])
[<bf15b7dc>] (wl1271_cmd_disconnect+0x0/0x14c [wl12xx])
[<bf158fd0>] (wl1271_unjoin+0x0/0x48 [wl12xx])
[<bf159070>] (wl1271_op_config+0x0/0x490 [wl12xx])
[<bf105084>] (ieee80211_hw_config+0x0/0x14c [mac80211])
[<bf113120>] (ieee80211_recalc_idle+0x0/0x4c [mac80211])
[<bf109a70>] (__ieee80211_scan_completed+0x0/0x1ac [mac80211])
[<bf109fd4>] (ieee80211_scan_work+0x0/0x484 [mac80211])
[<c00a197c>] (worker_thread+0x0/0x1e8)
[<c00a5874>] (kthread+0x0/0x90)

Signed-off-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>

drivers/net/wireless/wl12xx/main.c

@@ -1735,7 +1735,6 @@ static int wl1271_op_suspend(struct ieee80211_hw *hw,
 	}
 	/* flush any remaining work */
 	wl1271_debug(DEBUG_MAC80211, "flushing remaining works");
-	flush_delayed_work(&wl->scan_complete_work);
 
 	/*
 	 * disable and re-enable interrupts in order to flush
@@ -2786,6 +2785,44 @@ out:
 	return ret;
 }
 
+static void wl1271_op_cancel_hw_scan(struct ieee80211_hw *hw,
+				     struct ieee80211_vif *vif)
+{
+	struct wl1271 *wl = hw->priv;
+	int ret;
+
+	wl1271_debug(DEBUG_MAC80211, "mac80211 cancel hw scan");
+
+	mutex_lock(&wl->mutex);
+
+	if (wl->state == WL1271_STATE_OFF)
+		goto out;
+
+	if (wl->scan.state == WL1271_SCAN_STATE_IDLE)
+		goto out;
+
+	ret = wl1271_ps_elp_wakeup(wl);
+	if (ret < 0)
+		goto out;
+
+	if (wl->scan.state != WL1271_SCAN_STATE_DONE) {
+		ret = wl1271_scan_stop(wl);
+		if (ret < 0)
+			goto out_sleep;
+	}
+	wl->scan.state = WL1271_SCAN_STATE_IDLE;
+	memset(wl->scan.scanned_ch, 0, sizeof(wl->scan.scanned_ch));
+	wl->scan.req = NULL;
+	ieee80211_scan_completed(wl->hw, true);
+
+out_sleep:
+	wl1271_ps_elp_sleep(wl);
+out:
+	mutex_unlock(&wl->mutex);
+
+	cancel_delayed_work_sync(&wl->scan_complete_work);
+}
+
 static int wl1271_op_sched_scan_start(struct ieee80211_hw *hw,
 				      struct ieee80211_vif *vif,
 				      struct cfg80211_sched_scan_request *req,
@@ -3969,6 +4006,7 @@ static const struct ieee80211_ops wl1271_ops = {
 	.tx = wl1271_op_tx,
 	.set_key = wl1271_op_set_key,
 	.hw_scan = wl1271_op_hw_scan,
+	.cancel_hw_scan = wl1271_op_cancel_hw_scan,
 	.sched_scan_start = wl1271_op_sched_scan_start,
 	.sched_scan_stop = wl1271_op_sched_scan_stop,
 	.bss_info_changed = wl1271_op_bss_info_changed,