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>

1 files changed, 19 insertions, 13 deletions

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)
 {