cfg80211: express channels with a KHz component

Some bands (S1G) define channels centered on a non-integer
MHz. Give ieee80211_channel and cfg80211_chan_def a
freq_offset component where the final frequency can be
expressed as:

MHZ_TO_KHZ(chan->center_freq) + chan->freq_offset;

Also provide some helper functions to do the frequency
conversion and test for equality.

Retain the existing interface to frequency and channel
conversion helpers, and expose new ones which handle
frequencies in units of KHz.

Some internal functions (net/wireless/chan.c) pass around
a frequency value. Convert these to units of KHz.

mesh, ibss, wext, etc. are currently ignored.

Signed-off-by: Thomas Pedersen <thomas@adapt-ip.com>
Link: https://lore.kernel.org/r/20200402011810.22947-3-thomas@adapt-ip.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

5 files changed, 96 insertions, 69 deletions

diff --git a/net/wireless/chan.c b/net/wireless/chan.c
index fcac5c6366e1..d60e50a3b910 100644
--- a/net/wireless/chan.c
+++ b/net/wireless/chan.c
@@ -27,6 +27,7 @@ void cfg80211_chandef_create(struct cfg80211_chan_def *chandef,
 		return;
 
 	chandef->chan = chan;
+	chandef->freq1_offset = chan->freq_offset;
 	chandef->center_freq2 = 0;
 	chandef->edmg.bw_config = 0;
 	chandef->edmg.channels = 0;
@@ -153,7 +154,8 @@ bool cfg80211_chandef_valid(const struct cfg80211_chan_def *chandef)
 	case NL80211_CHAN_WIDTH_10:
 	case NL80211_CHAN_WIDTH_20:
 	case NL80211_CHAN_WIDTH_20_NOHT:
-		if (chandef->center_freq1 != control_freq)
+		if (ieee80211_chandef_to_khz(chandef) !=
+		    ieee80211_channel_to_khz(chandef->chan))
 			return false;
 		if (chandef->center_freq2)
 			return false;
@@ -386,10 +388,11 @@ static u32 cfg80211_get_start_freq(u32 center_freq,
 {
 	u32 start_freq;
 
-	if (bandwidth <= 20)
+	bandwidth = MHZ_TO_KHZ(bandwidth);
+	if (bandwidth <= MHZ_TO_KHZ(20))
 		start_freq = center_freq;
 	else
-		start_freq = center_freq - bandwidth/2 + 10;
+		start_freq = center_freq - bandwidth / 2 + MHZ_TO_KHZ(10);
 
 	return start_freq;
 }
@@ -399,10 +402,11 @@ static u32 cfg80211_get_end_freq(u32 center_freq,
 {
 	u32 end_freq;
 
-	if (bandwidth <= 20)
+	bandwidth = MHZ_TO_KHZ(bandwidth);
+	if (bandwidth <= MHZ_TO_KHZ(20))
 		end_freq = center_freq;
 	else
-		end_freq = center_freq + bandwidth/2 - 10;
+		end_freq = center_freq + bandwidth / 2 - MHZ_TO_KHZ(10);
 
 	return end_freq;
 }
@@ -417,8 +421,8 @@ static int cfg80211_get_chans_dfs_required(struct wiphy *wiphy,
 	start_freq = cfg80211_get_start_freq(center_freq, bandwidth);
 	end_freq = cfg80211_get_end_freq(center_freq, bandwidth);
 
-	for (freq = start_freq; freq <= end_freq; freq += 20) {
-		c = ieee80211_get_channel(wiphy, freq);
+	for (freq = start_freq; freq <= end_freq; freq += MHZ_TO_KHZ(20)) {
+		c = ieee80211_get_channel_khz(wiphy, freq);
 		if (!c)
 			return -EINVAL;
 
@@ -449,8 +453,8 @@ int cfg80211_chandef_dfs_required(struct wiphy *wiphy,
 			return -EINVAL;
 
 		ret = cfg80211_get_chans_dfs_required(wiphy,
-						      chandef->center_freq1,
-						      width);
+					ieee80211_chandef_to_khz(chandef),
+					width);
 		if (ret < 0)
 			return ret;
 		else if (ret > 0)
@@ -460,8 +464,8 @@ int cfg80211_chandef_dfs_required(struct wiphy *wiphy,
 			return 0;
 
 		ret = cfg80211_get_chans_dfs_required(wiphy,
-						      chandef->center_freq2,
-						      width);
+					MHZ_TO_KHZ(chandef->center_freq2),
+					width);
 		if (ret < 0)
 			return ret;
 		else if (ret > 0)
@@ -503,8 +507,8 @@ static int cfg80211_get_chans_dfs_usable(struct wiphy *wiphy,
 	 * DFS_AVAILABLE). Return number of usable channels
 	 * (require CAC). Allow DFS and non-DFS channel mix.
 	 */
-	for (freq = start_freq; freq <= end_freq; freq += 20) {
-		c = ieee80211_get_channel(wiphy, freq);
+	for (freq = start_freq; freq <= end_freq; freq += MHZ_TO_KHZ(20)) {
+		c = ieee80211_get_channel_khz(wiphy, freq);
 		if (!c)
 			return -EINVAL;
 
@@ -536,8 +540,9 @@ bool cfg80211_chandef_dfs_usable(struct wiphy *wiphy,
 	if (width < 0)
 		return false;
 
-	r1 = cfg80211_get_chans_dfs_usable(wiphy, chandef->center_freq1,
-					  width);
+	r1 = cfg80211_get_chans_dfs_usable(wiphy,
+					   MHZ_TO_KHZ(chandef->center_freq1),
+					   width);
 
 	if (r1 < 0)
 		return false;
@@ -546,8 +551,8 @@ bool cfg80211_chandef_dfs_usable(struct wiphy *wiphy,
 	case NL80211_CHAN_WIDTH_80P80:
 		WARN_ON(!chandef->center_freq2);
 		r2 = cfg80211_get_chans_dfs_usable(wiphy,
-						   chandef->center_freq2,
-						   width);
+					MHZ_TO_KHZ(chandef->center_freq2),
+					width);
 		if (r2 < 0)
 			return false;
 		break;
@@ -694,8 +699,8 @@ static bool cfg80211_get_chans_dfs_available(struct wiphy *wiphy,
 	 * If any channel in between is disabled or has not
 	 * had gone through CAC return false
 	 */
-	for (freq = start_freq; freq <= end_freq; freq += 20) {
-		c = ieee80211_get_channel(wiphy, freq);
+	for (freq = start_freq; freq <= end_freq; freq += MHZ_TO_KHZ(20)) {
+		c = ieee80211_get_channel_khz(wiphy, freq);
 		if (!c)
 			return false;
 
@@ -724,7 +729,8 @@ static bool cfg80211_chandef_dfs_available(struct wiphy *wiphy,
 	if (width < 0)
 		return false;
 
-	r = cfg80211_get_chans_dfs_available(wiphy, chandef->center_freq1,
+	r = cfg80211_get_chans_dfs_available(wiphy,
+					     MHZ_TO_KHZ(chandef->center_freq1),
 					     width);
 
 	/* If any of channels unavailable for cf1 just return */
@@ -735,8 +741,8 @@ static bool cfg80211_chandef_dfs_available(struct wiphy *wiphy,
 	case NL80211_CHAN_WIDTH_80P80:
 		WARN_ON(!chandef->center_freq2);
 		r = cfg80211_get_chans_dfs_available(wiphy,
-						     chandef->center_freq2,
-						     width);
+					MHZ_TO_KHZ(chandef->center_freq2),
+					width);
 		break;
 	default:
 		WARN_ON(chandef->center_freq2);
@@ -757,8 +763,8 @@ static unsigned int cfg80211_get_chans_dfs_cac_time(struct wiphy *wiphy,
 	start_freq = cfg80211_get_start_freq(center_freq, bandwidth);
 	end_freq = cfg80211_get_end_freq(center_freq, bandwidth);
 
-	for (freq = start_freq; freq <= end_freq; freq += 20) {
-		c = ieee80211_get_channel(wiphy, freq);
+	for (freq = start_freq; freq <= end_freq; freq += MHZ_TO_KHZ(20)) {
+		c = ieee80211_get_channel_khz(wiphy, freq);
 		if (!c)
 			return 0;
 
@@ -790,14 +796,14 @@ cfg80211_chandef_dfs_cac_time(struct wiphy *wiphy,
 		return 0;
 
 	t1 = cfg80211_get_chans_dfs_cac_time(wiphy,
-					     chandef->center_freq1,
+					     MHZ_TO_KHZ(chandef->center_freq1),
 					     width);
 
 	if (!chandef->center_freq2)
 		return t1;
 
 	t2 = cfg80211_get_chans_dfs_cac_time(wiphy,
-					     chandef->center_freq2,
+					     MHZ_TO_KHZ(chandef->center_freq2),
 					     width);
 
 	return max(t1, t2);
@@ -813,8 +819,8 @@ static bool cfg80211_secondary_chans_ok(struct wiphy *wiphy,
 	start_freq = cfg80211_get_start_freq(center_freq, bandwidth);
 	end_freq = cfg80211_get_end_freq(center_freq, bandwidth);
 
-	for (freq = start_freq; freq <= end_freq; freq += 20) {
-		c = ieee80211_get_channel(wiphy, freq);
+	for (freq = start_freq; freq <= end_freq; freq += MHZ_TO_KHZ(20)) {
+		c = ieee80211_get_channel_khz(wiphy, freq);
 		if (!c || c->flags & prohibited_flags)
 			return false;
 	}
@@ -976,13 +982,15 @@ bool cfg80211_chandef_usable(struct wiphy *wiphy,
 		prohibited_flags |= IEEE80211_CHAN_NO_OFDM;
 
 
-	if (!cfg80211_secondary_chans_ok(wiphy, chandef->center_freq1,
+	if (!cfg80211_secondary_chans_ok(wiphy,
+					 ieee80211_chandef_to_khz(chandef),
 					 width, prohibited_flags))
 		return false;
 
 	if (!chandef->center_freq2)
 		return true;
-	return cfg80211_secondary_chans_ok(wiphy, chandef->center_freq2,
+	return cfg80211_secondary_chans_ok(wiphy,
+					   MHZ_TO_KHZ(chandef->center_freq2),
 					   width, prohibited_flags);
 }
 EXPORT_SYMBOL(cfg80211_chandef_usable);
diff --git a/net/wireless/reg.c b/net/wireless/reg.c
index d476d4da0d09..0d74a31ef0ab 100644
--- a/net/wireless/reg.c
+++ b/net/wireless/reg.c
@@ -1658,22 +1658,23 @@ static uint32_t reg_rule_to_chan_bw_flags(const struct ieee80211_regdomain *regd
 					  const struct ieee80211_channel *chan)
 {
 	const struct ieee80211_freq_range *freq_range = NULL;
-	u32 max_bandwidth_khz, bw_flags = 0;
+	u32 max_bandwidth_khz, center_freq_khz, bw_flags = 0;
 
 	freq_range = &reg_rule->freq_range;
 
 	max_bandwidth_khz = freq_range->max_bandwidth_khz;
+	center_freq_khz = ieee80211_channel_to_khz(chan);
 	/* Check if auto calculation requested */
 	if (reg_rule->flags & NL80211_RRF_AUTO_BW)
 		max_bandwidth_khz = reg_get_max_bandwidth(regd, reg_rule);
 
 	/* If we get a reg_rule we can assume that at least 5Mhz fit */
 	if (!cfg80211_does_bw_fit_range(freq_range,
-					MHZ_TO_KHZ(chan->center_freq),
+					center_freq_khz,
 					MHZ_TO_KHZ(10)))
 		bw_flags |= IEEE80211_CHAN_NO_10MHZ;
 	if (!cfg80211_does_bw_fit_range(freq_range,
-					MHZ_TO_KHZ(chan->center_freq),
+					center_freq_khz,
 					MHZ_TO_KHZ(20)))
 		bw_flags |= IEEE80211_CHAN_NO_20MHZ;
 
@@ -1710,7 +1711,7 @@ static void handle_channel(struct wiphy *wiphy,
 
 	flags = chan->orig_flags;
 
-	reg_rule = freq_reg_info(wiphy, MHZ_TO_KHZ(chan->center_freq));
+	reg_rule = freq_reg_info(wiphy, ieee80211_channel_to_khz(chan));
 	if (IS_ERR(reg_rule)) {
 		/*
 		 * We will disable all channels that do not match our
@@ -1729,13 +1730,13 @@ static void handle_channel(struct wiphy *wiphy,
 		if (lr->initiator == NL80211_REGDOM_SET_BY_DRIVER &&
 		    request_wiphy && request_wiphy == wiphy &&
 		    request_wiphy->regulatory_flags & REGULATORY_STRICT_REG) {
-			pr_debug("Disabling freq %d MHz for good\n",
-				 chan->center_freq);
+			pr_debug("Disabling freq %d.%03d MHz for good\n",
+				 chan->center_freq, chan->freq_offset);
 			chan->orig_flags |= IEEE80211_CHAN_DISABLED;
 			chan->flags = chan->orig_flags;
 		} else {
-			pr_debug("Disabling freq %d MHz\n",
-				 chan->center_freq);
+			pr_debug("Disabling freq %d.%03d MHz\n",
+				 chan->center_freq, chan->freq_offset);
 			chan->flags |= IEEE80211_CHAN_DISABLED;
 		}
 		return;
@@ -1936,7 +1937,7 @@ static void handle_reg_beacon(struct wiphy *wiphy, unsigned int chan_idx,
 	sband = wiphy->bands[reg_beacon->chan.band];
 	chan = &sband->channels[chan_idx];
 
-	if (likely(chan->center_freq != reg_beacon->chan.center_freq))
+	if (likely(!ieee80211_channel_equal(chan, &reg_beacon->chan)))
 		return;
 
 	if (chan->beacon_found)
@@ -2269,18 +2270,18 @@ static void handle_channel_custom(struct wiphy *wiphy,
 	u32 bw_flags = 0;
 	const struct ieee80211_reg_rule *reg_rule = NULL;
 	const struct ieee80211_power_rule *power_rule = NULL;
-	u32 bw;
+	u32 bw, center_freq_khz;
 
+	center_freq_khz = ieee80211_channel_to_khz(chan);
 	for (bw = MHZ_TO_KHZ(20); bw >= min_bw; bw = bw / 2) {
-		reg_rule = freq_reg_info_regd(MHZ_TO_KHZ(chan->center_freq),
-					      regd, bw);
+		reg_rule = freq_reg_info_regd(center_freq_khz, regd, bw);
 		if (!IS_ERR(reg_rule))
 			break;
 	}
 
 	if (IS_ERR_OR_NULL(reg_rule)) {
-		pr_debug("Disabling freq %d MHz as custom regd has no rule that fits it\n",
-			 chan->center_freq);
+		pr_debug("Disabling freq %d.%03d MHz as custom regd has no rule that fits it\n",
+			 chan->center_freq, chan->freq_offset);
 		if (wiphy->regulatory_flags & REGULATORY_WIPHY_SELF_MANAGED) {
 			chan->flags |= IEEE80211_CHAN_DISABLED;
 		} else {
@@ -3337,8 +3338,8 @@ static bool pending_reg_beacon(struct ieee80211_channel *beacon_chan)
 	struct reg_beacon *pending_beacon;
 
 	list_for_each_entry(pending_beacon, &reg_pending_beacons, list)
-		if (beacon_chan->center_freq ==
-		    pending_beacon->chan.center_freq)
+		if (ieee80211_channel_equal(beacon_chan,
+					    &pending_beacon->chan))
 			return true;
 	return false;
 }
@@ -3367,9 +3368,10 @@ int regulatory_hint_found_beacon(struct wiphy *wiphy,
 	if (!reg_beacon)
 		return -ENOMEM;
 
-	pr_debug("Found new beacon on frequency: %d MHz (Ch %d) on %s\n",
-		 beacon_chan->center_freq,
-		 ieee80211_frequency_to_channel(beacon_chan->center_freq),
+	pr_debug("Found new beacon on frequency: %d.%03d MHz (Ch %d) on %s\n",
+		 beacon_chan->center_freq, beacon_chan->freq_offset,
+		 ieee80211_freq_khz_to_channel(
+			 ieee80211_channel_to_khz(beacon_chan)),
 		 wiphy_name(wiphy));
 
 	memcpy(&reg_beacon->chan, beacon_chan,
diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index 4000382aef48..74ea4cfb39fb 100644
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -1322,8 +1322,8 @@ cfg80211_get_bss_channel(struct wiphy *wiphy, const u8 *ie, size_t ielen,
 		return channel;
 	}
 
-	freq = ieee80211_channel_to_frequency(channel_number, channel->band);
-	alt_channel = ieee80211_get_channel(wiphy, freq);
+	freq = ieee80211_channel_to_freq_khz(channel_number, channel->band);
+	alt_channel = ieee80211_get_channel_khz(wiphy, freq);
 	if (!alt_channel) {
 		if (channel->band == NL80211_BAND_2GHZ) {
 			/*
diff --git a/net/wireless/trace.h b/net/wireless/trace.h
index ee736620f1e3..53c887ea67c7 100644
--- a/net/wireless/trace.h
+++ b/net/wireless/trace.h
@@ -112,24 +112,29 @@
 	} while (0)
 
 #define CHAN_ENTRY __field(enum nl80211_band, band) \
-		   __field(u32, center_freq)
+		   __field(u32, center_freq)		\
+		   __field(u16, freq_offset)
 #define CHAN_ASSIGN(chan)					  \
 	do {							  \
 		if (chan) {					  \
 			__entry->band = chan->band;		  \
 			__entry->center_freq = chan->center_freq; \
+			__entry->freq_offset = chan->freq_offset; \
 		} else {					  \
 			__entry->band = 0;			  \
 			__entry->center_freq = 0;		  \
+			__entry->freq_offset = 0;		  \
 		}						  \
 	} while (0)
-#define CHAN_PR_FMT "band: %d, freq: %u"
-#define CHAN_PR_ARG __entry->band, __entry->center_freq
+#define CHAN_PR_FMT "band: %d, freq: %u.%03u"
+#define CHAN_PR_ARG __entry->band, __entry->center_freq, __entry->freq_offset
 
 #define CHAN_DEF_ENTRY __field(enum nl80211_band, band)		\
 		       __field(u32, control_freq)			\
+		       __field(u32, freq_offset)			\
 		       __field(u32, width)				\
 		       __field(u32, center_freq1)			\
+		       __field(u32, freq1_offset)			\
 		       __field(u32, center_freq2)
 #define CHAN_DEF_ASSIGN(chandef)					\
 	do {								\
@@ -137,21 +142,27 @@
 			__entry->band = (chandef)->chan->band;		\
 			__entry->control_freq =				\
 				(chandef)->chan->center_freq;		\
+			__entry->freq_offset =				\
+				(chandef)->chan->freq_offset;		\
 			__entry->width = (chandef)->width;		\
 			__entry->center_freq1 = (chandef)->center_freq1;\
+			__entry->freq1_offset = (chandef)->freq1_offset;\
 			__entry->center_freq2 = (chandef)->center_freq2;\
 		} else {						\
 			__entry->band = 0;				\
 			__entry->control_freq = 0;			\
+			__entry->freq_offset = 0;			\
 			__entry->width = 0;				\
 			__entry->center_freq1 = 0;			\
+			__entry->freq1_offset = 0;			\
 			__entry->center_freq2 = 0;			\
 		}							\
 	} while (0)
 #define CHAN_DEF_PR_FMT							\
-	"band: %d, control freq: %u, width: %d, cf1: %u, cf2: %u"
+	"band: %d, control freq: %u.%03u, width: %d, cf1: %u.%03u, cf2: %u"
 #define CHAN_DEF_PR_ARG __entry->band, __entry->control_freq,		\
-			__entry->width, __entry->center_freq1,		\
+			__entry->freq_offset, __entry->width,		\
+			__entry->center_freq1, __entry->freq1_offset,	\
 			__entry->center_freq2
 
 #define SINFO_ENTRY __field(int, generation)	    \
diff --git a/net/wireless/util.c b/net/wireless/util.c
index 123d6ce79b8e..df75e58eca5d 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -72,7 +72,7 @@ u32 ieee80211_mandatory_rates(struct ieee80211_supported_band *sband,
 }
 EXPORT_SYMBOL(ieee80211_mandatory_rates);
 
-int ieee80211_channel_to_frequency(int chan, enum nl80211_band band)
+u32 ieee80211_channel_to_freq_khz(int chan, enum nl80211_band band)
 {
 	/* see 802.11 17.3.8.3.2 and Annex J
 	 * there are overlapping channel numbers in 5GHz and 2GHz bands */
@@ -81,15 +81,15 @@ int ieee80211_channel_to_frequency(int chan, enum nl80211_band band)
 	switch (band) {
 	case NL80211_BAND_2GHZ:
 		if (chan == 14)
-			return 2484;
+			return MHZ_TO_KHZ(2484);
 		else if (chan < 14)
-			return 2407 + chan * 5;
+			return MHZ_TO_KHZ(2407 + chan * 5);
 		break;
 	case NL80211_BAND_5GHZ:
 		if (chan >= 182 && chan <= 196)
-			return 4000 + chan * 5;
+			return MHZ_TO_KHZ(4000 + chan * 5);
 		else
-			return 5000 + chan * 5;
+			return MHZ_TO_KHZ(5000 + chan * 5);
 		break;
 	case NL80211_BAND_6GHZ:
 		/* see 802.11ax D4.1 27.3.22.2 */
@@ -98,17 +98,20 @@ int ieee80211_channel_to_frequency(int chan, enum nl80211_band band)
 		break;
 	case NL80211_BAND_60GHZ:
 		if (chan < 7)
-			return 56160 + chan * 2160;
+			return MHZ_TO_KHZ(56160 + chan * 2160);
 		break;
 	default:
 		;
 	}
 	return 0; /* not supported */
 }
-EXPORT_SYMBOL(ieee80211_channel_to_frequency);
+EXPORT_SYMBOL(ieee80211_channel_to_freq_khz);
 
-int ieee80211_frequency_to_channel(int freq)
+int ieee80211_freq_khz_to_channel(u32 freq)
 {
+	/* TODO: just handle MHz for now */
+	freq = KHZ_TO_MHZ(freq);
+
 	/* see 802.11 17.3.8.3.2 and Annex J */
 	if (freq == 2484)
 		return 14;
@@ -126,9 +129,10 @@ int ieee80211_frequency_to_channel(int freq)
 	else
 		return 0;
 }
-EXPORT_SYMBOL(ieee80211_frequency_to_channel);
+EXPORT_SYMBOL(ieee80211_freq_khz_to_channel);
 
-struct ieee80211_channel *ieee80211_get_channel(struct wiphy *wiphy, int freq)
+struct ieee80211_channel *ieee80211_get_channel_khz(struct wiphy *wiphy,
+						    u32 freq)
 {
 	enum nl80211_band band;
 	struct ieee80211_supported_band *sband;
@@ -141,14 +145,16 @@ struct ieee80211_channel *ieee80211_get_channel(struct wiphy *wiphy, int freq)
 			continue;
 
 		for (i = 0; i < sband->n_channels; i++) {
-			if (sband->channels[i].center_freq == freq)
-				return &sband->channels[i];
+			struct ieee80211_channel *chan = &sband->channels[i];
+
+			if (ieee80211_channel_to_khz(chan) == freq)
+				return chan;
 		}
 	}
 
 	return NULL;
 }
-EXPORT_SYMBOL(ieee80211_get_channel);
+EXPORT_SYMBOL(ieee80211_get_channel_khz);
 
 static void set_mandatory_flags_band(struct ieee80211_supported_band *sband)
 {