On Sat December 25 2010 01:46:00 Dave Kilroy wrote:
> On Fri, Dec 24, 2010 at 7:44 AM, Bruno Randolf <br1@xxxxxxxxxxx> wrote:
> > Extend channel to frequency mapping for 802.11j Japan 4.9GHz band,
> > according to IEEE802.11 section 17.3.8.3.2 and Annex J. Because there
> > are now overlapping channel numbers in the 2GHz and 5GHz band we can't
> > map from channel to frequency without knowing the band. This is no
> > problem as in most contexts we know the band. In places where we don't
> > know the band (and WEXT compatibility) we assume the 2GHz band for
> > channels below 14.
> >
> > Signed-off-by: Bruno Randolf <br1@xxxxxxxxxxx>
> > ---
> > -int ieee80211_channel_to_frequency(int chan)
> > +int ieee80211_channel_to_frequency(int chan, enum ieee80211_band band)
> > {
> > - if (chan < 14)
> > - return 2407 + chan * 5;
> > -
> > - if (chan == 14)
> > - return 2484;
> > -
> > - /* FIXME: 802.11j 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 (band == IEEE80211_BAND_5GHZ) {
> > + if (chan >= 182 && chan <= 196)
> > + return 4000 + chan * 5;
> > + else
> > + return 5000 + chan * 5;
> > + } else { /* IEEE80211_BAND_2GHZ */
> > + if (chan == 14)
> > + return 2484;
> > + else if (chan < 14)
> > + return 2407 + chan * 5;
> > + else
> > + return 0; /* not supported */
> > + }
> > }
> > EXPORT_SYMBOL(ieee80211_channel_to_frequency);
> >
> > int ieee80211_frequency_to_channel(int freq)
> > {
> > + /* see 802.11 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: 802.11j 17.3.8.3.2 */
> > - return freq/5 - 1000;
> > + else if (freq >= 4910 && freq <= 4980)
> > + return (freq - 4000) / 5;
> > + else
> > + return (freq - 5000) / 5;
> > }
> > EXPORT_SYMBOL(ieee80211_frequency_to_channel);
>
> You don't have to use them, but there are a few channel/frequency
> conversion routines in include/ieee80211.h which could be reused in
> these functions.
Thanks for that info, I didn't know about those functions. I just checked
them and it seems most of them are not used, AFAICT:
ieee80211_fhss_chan_to_freq - not used
ieee80211_freq_to_fhss_chan - not used
ieee80211_hr_chan_to_freq - not used
ieee80211_freq_to_hr_chan - not used
ieee80211_erp_chan_to_freq - not used
ieee80211_freq_to_erp_chan - not used
ieee80211_ofdm_chan_to_freq - not used
ieee80211_freq_to_ofdm_chan - not used
The only two which are used are for 2GHz channels:
ieee80211_dsss_chan_to_freq - atmel, airo, wl3501_cs, orinoco, rndis_wlan
ieee80211_freq_to_dsss_chan - atmel, airo, orinoco, zd1201
Anyhow i guess it would make sense to have a common channel to frequency
mapping function for mac80211 and other wireless drivers? The problem is now
we have to use enum ieee80211_band which is defined cfg80211.h...
Any opinions?
bruno
--
To unsubscribe from this list: send the line "unsubscribe linux-wireless" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
