2013-09-26 16:45:54

by Bruno Randolf

Subject: [PATCH] iw: sync frequency to channel mapping with kernel

Use ieee80211_frequency_to_channel() and ieee80211_channel_to_frequency() as in
the current kernel. This is necessary to properly print the channel numbers for
4.9GHz channels which can be used in Japan.

Signed-off-by: Bruno Randolf <[email protected]>
---
iw.h | 2 +-
phy.c | 8 ++++++--
util.c | 54 +++++++++++++++++++++++++++++++++++-------------------
3 files changed, 42 insertions(+), 22 deletions(-)

diff --git a/iw.h b/iw.h
index 854d356..317f0a6 100644
--- a/iw.h
+++ b/iw.h
@@ -148,7 +148,7 @@ void print_vht_info(__u32 capa, const __u8 *mcs);
char *channel_width_name(enum nl80211_chan_width width);
const char *iftype_name(enum nl80211_iftype iftype);
const char *command_name(enum nl80211_commands cmd);
-int ieee80211_channel_to_frequency(int chan);
+int ieee80211_channel_to_frequency(int chan, enum nl80211_band band);
int ieee80211_frequency_to_channel(int freq);

void print_ssid_escaped(const uint8_t len, const uint8_t *data);
diff --git a/phy.c b/phy.c
index 7f8ce26..58636af 100644
--- a/phy.c
+++ b/phy.c
@@ -113,8 +113,12 @@ static int handle_freqchan(struct nl_msg *msg, bool chan,
if (*end)
return 1;

- if (chan)
- freq = ieee80211_channel_to_frequency(freq);
+ if (chan) {
+ enum nl80211_band band;
+ band = freq <= 14 ? NL80211_BAND_2GHZ : NL80211_BAND_5GHZ;
+ freq = ieee80211_channel_to_frequency(freq, band);
+ }
+

NLA_PUT_U32(msg, NL80211_ATTR_WIPHY_FREQ, freq);

diff --git a/util.c b/util.c
index e3d0c27..4542749 100644
--- a/util.c
+++ b/util.c
@@ -260,34 +260,50 @@ const char *command_name(enum nl80211_commands cmd)
return cmdbuf;
}

-int ieee80211_channel_to_frequency(int chan)
+int ieee80211_channel_to_frequency(int chan, enum nl80211_band band)
{
- if (chan < 14)
- return 2407 + chan * 5;
-
- if (chan == 14)
- return 2484;
-
- /* FIXME: dot11ChannelStartingFactor (802.11-2007 17.3.8.3.2) */
- return (chan + 1000) * 5;
+ /* see 802.11 17.3.8.3.2 and Annex J
+ * there are overlapping channel numbers in 5GHz and 2GHz bands */
+ if (chan <= 0)
+ return 0; /* not supported */
+ switch (band) {
+ case NL80211_BAND_2GHZ:
+ if (chan == 14)
+ return 2484;
+ else if (chan < 14)
+ return 2407 + chan * 5;
+ break;
+ case NL80211_BAND_5GHZ:
+ if (chan >= 182 && chan <= 196)
+ return 4000 + chan * 5;
+ else
+ return 5000 + chan * 5;
+ break;
+ case NL80211_BAND_60GHZ:
+ if (chan < 5)
+ return 56160 + chan * 2160;
+ break;
+ default:
+ ;
+ }
+ return 0; /* not supported */
}

int ieee80211_frequency_to_channel(int freq)
{
+ /* see 802.11-2007 17.3.8.3.2 and Annex J */
if (freq == 2484)
return 14;
-
- if (freq < 2484)
+ else if (freq < 2484)
return (freq - 2407) / 5;
-
- /* FIXME: dot11ChannelStartingFactor (802.11-2007 17.3.8.3.2) */
- if (freq < 45000)
- return freq/5 - 1000;
-
- if (freq >= 58320 && freq <= 64800)
+ else if (freq >= 4910 && freq <= 4980)
+ return (freq - 4000) / 5;
+ else if (freq <= 45000) /* DMG band lower limit */
+ return (freq - 5000) / 5;
+ else if (freq >= 58320 && freq <= 64800)
return (freq - 56160) / 2160;
-
- return 0;
+ else
+ return 0;
}

void print_ssid_escaped(const uint8_t len, const uint8_t *data)
--
1.8.1.2

2013-09-30 09:32:37

by Johannes Berg

Subject: Re: [PATCH] iw: sync frequency to channel mapping with kernel

On Thu, 2013-09-26 at 17:45 +0100, Bruno Randolf wrote:
> Use ieee80211_frequency_to_channel() and ieee80211_channel_to_frequency() as in
> the current kernel. This is necessary to properly print the channel numbers for
> 4.9GHz channels which can be used in Japan.

Applied.

johannes