[RFT 0/2] cfg80211: UNII regulatory hints

[RFT 0/2] cfg80211: UNII regulatory hints

[Luis R. Rodriguez]

From: "Luis R. Rodriguez" <mcgrof@do-not-panic.com>

It was hinted to me a while ago that we can enhance
beacon hints a little more by taking advantage of
common regulatory assumptions globally on UNII 1
and UNII 3. This implements that idea.

What this will do is in short enable to lift passive
scan flags off of 5 GHz channels *faster* when cards
are world roaming. This means that we can also initiate
communication on channels on either UNII 1 or UNII 3
faster than before when world roaming.

Credit goes got David Quan for the idea.

Luis R. Rodriguez (2):
  cfg80211: add a helper for processing 5 GHz beacon hints
  cfg80211: add 5 GHz UNII band regulatory hints

 net/wireless/reg.c |  167 +++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 151 insertions(+), 16 deletions(-)

-- 
1.7.10.4

[RFT 1/2] cfg80211: add a helper for processing 5 GHz beacon hints

[Luis R. Rodriguez]

From: "Luis R. Rodriguez" <mcgrof@do-not-panic.com>

Add a helper for doing the work required for processing
a beacon hint. This allows us to re-use the code if
we later want to do the same processing.

This commit has no functional change, it only introduces
a helper.

Signed-off-by: Luis R. Rodriguez <mcgrof@do-not-panic.com>
---
 net/wireless/reg.c |   45 +++++++++++++++++++++++++++++----------------
 1 file changed, 29 insertions(+), 16 deletions(-)

diff --git a/net/wireless/reg.c b/net/wireless/reg.c
index 2ded3c7..8525ece 100644
--- a/net/wireless/reg.c
+++ b/net/wireless/reg.c
@@ -1028,30 +1028,19 @@ static bool ignore_reg_update(struct wiphy *wiphy,
 	return false;
 }
 
-static void handle_reg_beacon(struct wiphy *wiphy,
-			      unsigned int chan_idx,
-			      struct reg_beacon *reg_beacon)
+static bool reg_chan_process_beacon_hint(struct wiphy *wiphy,
+					 struct ieee80211_channel *chan)
 {
-	struct ieee80211_supported_band *sband;
-	struct ieee80211_channel *chan;
-	bool channel_changed = false;
 	struct ieee80211_channel chan_before;
-
-	assert_cfg80211_lock();
-
-	sband = wiphy->bands[reg_beacon->chan.band];
-	chan = &sband->channels[chan_idx];
-
-	if (likely(chan->center_freq != reg_beacon->chan.center_freq))
-		return;
+	bool channel_changed = false;
 
 	if (chan->beacon_found)
-		return;
+		return false;
 
 	chan->beacon_found = true;
 
 	if (wiphy->flags & WIPHY_FLAG_DISABLE_BEACON_HINTS)
-		return;
+		return false;
 
 	chan_before.center_freq = chan->center_freq;
 	chan_before.flags = chan->flags;
@@ -1068,6 +1057,30 @@ static void handle_reg_beacon(struct wiphy *wiphy,
 
 	if (channel_changed)
 		nl80211_send_beacon_hint_event(wiphy, &chan_before, chan);
+
+	return channel_changed;
+}
+
+static void handle_reg_beacon(struct wiphy *wiphy,
+			      unsigned int chan_idx,
+			      struct reg_beacon *reg_beacon)
+{
+	struct ieee80211_supported_band *sband;
+	struct ieee80211_channel *chan;
+	bool channel_changed = false;
+
+	assert_cfg80211_lock();
+
+	sband = wiphy->bands[reg_beacon->chan.band];
+	chan = &sband->channels[chan_idx];
+
+	if (likely(chan->center_freq != reg_beacon->chan.center_freq))
+		return;
+
+	channel_changed = reg_chan_process_beacon_hint(wiphy, chan);
+
+	if (channel_changed)
+		return; /* some band hint could potenially go here */
 }
 
 /*
-- 
1.7.10.4

[RFT 2/2] cfg80211: add 5 GHz UNII band regulatory hints

[Luis R. Rodriguez]

From: "Luis R. Rodriguez" <mcgrof@do-not-panic.com>

It turns out that what is known as UNII 1 (5180 MHz - 5240 MHz)
and UNII 3 (5745 MHz - 5825 MHz) share the same regulatory
permissions globally. This fact can be used to enable enhancing
world roaming quite a bit by taking advantage of beacon hints [0].

If we receive a beacon hint on UNII 1 it means we can not only
take advantage of that beacon hint to lift passive scan flags
on that channel but all other UNII 1 channels. The same applies
to UNII 3.

This implements UNII 1 and UNII 3 beacon hints.

[0] http://wireless.kernel.org/en/developers/Regulatory/processing_rules#Beacon_hints

Signed-off-by: Luis R. Rodriguez <mcgrof@do-not-panic.com>
---
 net/wireless/reg.c |  124 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 123 insertions(+), 1 deletion(-)

diff --git a/net/wireless/reg.c b/net/wireless/reg.c
index 8525ece..2366ea2 100644
--- a/net/wireless/reg.c
+++ b/net/wireless/reg.c
@@ -1061,6 +1061,128 @@ static bool reg_chan_process_beacon_hint(struct wiphy *wiphy,
 	return channel_changed;
 }
 
+enum reg_5ghz_unii_band {
+	REG_5GHZ_UNKNOWN,	/* all others */
+	REG_5GHZ_UNII_1,	/* 5180 MHz - 5240 MHz */
+	REG_5GHZ_UNII_2,	/* 5260 MHz - 5320 MHz */
+	REG_5GHZ_MID_BAND,	/* 5500 MHz - 5700 MHz */
+	REG_5GHZ_UNII_3,	/* 5745 MHz - 5825 MHz */
+};
+
+static bool reg_is_5ghz_unii_1(struct ieee80211_channel *chan)
+{
+	if (chan->center_freq >= 5180 &&
+	    chan->center_freq <= 5240)
+		return true;
+	return false;
+}
+
+static bool reg_is_5ghz_unii_2(struct ieee80211_channel *chan)
+{
+	if (chan->center_freq >= 5260 &&
+	    chan->center_freq <= 5320 )
+		return true;
+	return false;
+}
+
+static bool reg_is_5ghz_mid_band(struct ieee80211_channel *chan)
+{
+	if (chan->center_freq >= 5500 &&
+	    chan->center_freq <= 5700)
+		return true;
+	return false;
+}
+
+static bool reg_is_5ghz_unii_3(struct ieee80211_channel *chan)
+{
+	if (chan->center_freq >= 5745 &&
+	    chan->center_freq <= 5825)
+		return true;
+	return false;
+}
+
+static enum reg_5ghz_unii_band
+reg_get_5ghz_unii_band(struct ieee80211_channel *chan)
+{
+	if (reg_is_5ghz_unii_1(chan))
+		return REG_5GHZ_UNII_1;
+	if (reg_is_5ghz_unii_2(chan))
+		return REG_5GHZ_UNII_2;
+	if (reg_is_5ghz_mid_band(chan))
+		return REG_5GHZ_MID_BAND;
+	if (reg_is_5ghz_mid_band(chan))
+		return REG_5GHZ_UNII_3;
+
+	return REG_5GHZ_UNKNOWN;
+}
+
+static void reg_unii_5ghz_beacon_hint_unii(struct wiphy *wiphy,
+					   struct ieee80211_channel *chan,
+					   enum reg_5ghz_unii_band unii_band)
+{
+	struct ieee80211_supported_band *sband;
+	unsigned int i;
+
+	assert_cfg80211_lock();
+
+	sband = wiphy->bands[chan->band];
+
+	/*
+	 * Only process UNII 1 hints for UNII 1 channels
+	 * Only process UNII 3 hints for UNII 3 channels
+	 */
+	for (i = 0; i < sband->n_channels; i++) {
+		struct ieee80211_channel *c = &sband->channels[i];
+
+		switch (unii_band) {
+		case REG_5GHZ_UNII_1:
+			if (!reg_is_5ghz_unii_1(c))
+				continue;
+			break;
+		case REG_5GHZ_UNII_3:
+			if (!reg_is_5ghz_unii_3(c))
+				continue;
+			break;
+		default:
+			WARN_ONCE(1, "unexpected regulatory unii hint\n");
+			continue;
+		}
+
+		reg_chan_process_beacon_hint(wiphy, chan);
+	}
+
+	REG_DBG_PRINT("Processed 5 GHz UNII %d beacon hint\n",
+		      (unii_band == REG_5GHZ_UNII_1) ? 1 : 3);
+}
+
+static void reg_unii_5ghz_beacon_hint(struct wiphy *wiphy,
+				      struct ieee80211_channel *chan)
+{
+	enum reg_5ghz_unii_band unii_band = reg_get_5ghz_unii_band(chan);
+
+	switch (unii_band) {
+	case REG_5GHZ_UNKNOWN:
+		return;
+	/*
+	 * These should not happen given that typically DFS
+	 * is always enabled on the rest of the 5 GHz frequencies.
+	 * We'll just bail out.
+	 */
+	case REG_5GHZ_UNII_2:
+	case REG_5GHZ_MID_BAND:
+		return;
+	/*
+	 * 5 GHz UNII hints are only enabled for UNII1 and UNII3
+	 */
+	case REG_5GHZ_UNII_1:
+	case REG_5GHZ_UNII_3:
+		reg_unii_5ghz_beacon_hint_unii(wiphy, chan, unii_band);
+		break;
+	default:
+		break;
+	}
+}
+
 static void handle_reg_beacon(struct wiphy *wiphy,
 			      unsigned int chan_idx,
 			      struct reg_beacon *reg_beacon)
@@ -1080,7 +1202,7 @@ static void handle_reg_beacon(struct wiphy *wiphy,
 	channel_changed = reg_chan_process_beacon_hint(wiphy, chan);
 
 	if (channel_changed)
-		return; /* some band hint could potenially go here */
+		reg_unii_5ghz_beacon_hint(wiphy, chan);
 }
 
 /*
-- 
1.7.10.4

Re: [RFT 2/2] cfg80211: add 5 GHz UNII band regulatory hints

[Arend van Spriel]

On 08/11/2012 02:25 AM, Luis R. Rodriguez wrote:
> +static void reg_unii_5ghz_beacon_hint_unii(struct wiphy *wiphy,
> +					   struct ieee80211_channel *chan,
> +					   enum reg_5ghz_unii_band unii_band)
> +{
> +	struct ieee80211_supported_band *sband;
> +	unsigned int i;
> +
> +	assert_cfg80211_lock();
> +
> +	sband = wiphy->bands[chan->band];
> +
> +	/*
> +	 * Only process UNII 1 hints for UNII 1 channels
> +	 * Only process UNII 3 hints for UNII 3 channels
> +	 */
> +	for (i = 0; i < sband->n_channels; i++) {
> +		struct ieee80211_channel *c = &sband->channels[i];
> +
> +		switch (unii_band) {
> +		case REG_5GHZ_UNII_1:
> +			if (!reg_is_5ghz_unii_1(c))
> +				continue;
> +			break;
> +		case REG_5GHZ_UNII_3:
> +			if (!reg_is_5ghz_unii_3(c))
> +				continue;
> +			break;
> +		default:
> +			WARN_ONCE(1, "unexpected regulatory unii hint\n");
> +			continue;
> +		}
> +
> +		reg_chan_process_beacon_hint(wiphy, chan);

Not sure, but reading the description I think variable 'c' should be
passed here instead of 'chan'.

> +	}

Gr. AvS