mac80211: support hw scan while idle

Currently, mac80211 goes to idle-off before starting a scan.
However, some devices that implement hw scan might not
need going idle-off in order to perform a hw scan, and
thus saving some energy and simplifying their state machine.

(Note that this is also the case for sched scan - it
currently doesn't make mac80211 go idle-off)

Add a new flag to indicate support for hw scan while idle.

Signed-off-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/mac80211/debugfs.c b/net/mac80211/debugfs.c
index affe64b..483e96e 100644
--- a/net/mac80211/debugfs.c
+++ b/net/mac80211/debugfs.c
@@ -263,6 +263,8 @@
 		sf += snprintf(buf + sf, mxln - sf, "AP_LINK_PS\n");
 	if (local->hw.flags & IEEE80211_HW_TX_AMPDU_SETUP_IN_HW)
 		sf += snprintf(buf + sf, mxln - sf, "TX_AMPDU_SETUP_IN_HW\n");
+	if (local->hw.flags & IEEE80211_HW_SCAN_WHILE_IDLE)
+		sf += snprintf(buf + sf, mxln - sf, "SCAN_WHILE_IDLE\n");
 
 	rv = simple_read_from_buffer(user_buf, count, ppos, buf, strlen(buf));
 	kfree(buf);
diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index 19f0818..6b3cd65 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -1332,7 +1332,8 @@
 		wk->sdata->vif.bss_conf.idle = false;
 	}
 
-	if (local->scan_sdata) {
+	if (local->scan_sdata &&
+	    !(local->hw.flags & IEEE80211_HW_SCAN_WHILE_IDLE)) {
 		scanning = true;
 		local->scan_sdata->vif.bss_conf.idle = false;
 	}
diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index 362e89d..831a5bd 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -697,6 +697,9 @@
 	    )
 		return -EINVAL;
 
+	if ((hw->flags & IEEE80211_HW_SCAN_WHILE_IDLE) && !local->ops->hw_scan)
+		return -EINVAL;
+
 	if (hw->max_report_rates == 0)
 		hw->max_report_rates = hw->max_rates;