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In-Reply-To: <20110107052600.18730.98168.stgit@localhost6.localdomain6>
References: <20110107052600.18730.98168.stgit@localhost6.localdomain6>
Date: Fri, 7 Jan 2011 07:45:00 -0500
Message-ID: <AANLkTikfUb+-Phy4nwdr-Vsf2Sg8dxO7-YepbqnfwyYt@mail.gmail.com>
Subject: Re: [PATCH] cfg80211: Extend channel to frequency mapping for 802.11j
From: Brian Prodoehl <bprodoehl@gmail.com>
To: Bruno Randolf <br1@einfach.org>
Cc: johannes@sipsolutions.net, linville@tuxdriver.com,
	linux-wireless@vger.kernel.org
Content-Type: text/plain; charset=ISO-8859-1
Sender: linux-wireless-owner@vger.kernel.org

On Fri, Jan 7, 2011 at 12:26 AM, Bruno Randolf <br1@einfach.org> 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.
>
> This patch does not implement all channel to frequency mappings defined in
> 802.11, it's just an extension for 802.11j 20MHz channels. 5MHz and 10MHz
> channels as well as 802.11y channels have been omitted.
>
> Signed-off-by: Bruno Randolf <br1@einfach.org>
> ---
> ?include/net/cfg80211.h ? ? | ? ?3 ++-
> ?net/mac80211/ibss.c ? ? ? ?| ? ?3 ++-
> ?net/mac80211/mesh.c ? ? ? ?| ? ?2 +-
> ?net/mac80211/mlme.c ? ? ? ?| ? ?8 +++++---
> ?net/mac80211/scan.c ? ? ? ?| ? ?3 ++-
> ?net/wireless/reg.c ? ? ? ? | ? ?6 +++---
> ?net/wireless/util.c ? ? ? ?| ? 36 ++++++++++++++++++++++--------------
> ?net/wireless/wext-compat.c | ? ?5 ++++-
> ?8 files changed, 41 insertions(+), 25 deletions(-)
>
> diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
> index bcc9f44..cfaac36 100644
> --- a/include/net/cfg80211.h
> +++ b/include/net/cfg80211.h
> @@ -1788,8 +1788,9 @@ static inline void *wdev_priv(struct wireless_dev *wdev)
> ?/**
> ?* ieee80211_channel_to_frequency - convert channel number to frequency
> ?* @chan: channel number
> + * @band: band, necessary due to channel number overlap
> ?*/
> -extern int ieee80211_channel_to_frequency(int chan);
> +extern int ieee80211_channel_to_frequency(int chan, enum ieee80211_band band);
>
> ?/**
> ?* ieee80211_frequency_to_channel - convert frequency to channel number
> diff --git a/net/mac80211/ibss.c b/net/mac80211/ibss.c
> index 53c7077..775fb63 100644
> --- a/net/mac80211/ibss.c
> +++ b/net/mac80211/ibss.c
> @@ -270,7 +270,8 @@ static void ieee80211_rx_bss_info(struct ieee80211_sub_if_data *sdata,
> ? ? ? ?enum ieee80211_band band = rx_status->band;
>
> ? ? ? ?if (elems->ds_params && elems->ds_params_len == 1)
> - ? ? ? ? ? ? ? freq = ieee80211_channel_to_frequency(elems->ds_params[0]);
> + ? ? ? ? ? ? ? freq = ieee80211_channel_to_frequency(elems->ds_params[0],
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? band);
> ? ? ? ?else
> ? ? ? ? ? ? ? ?freq = rx_status->freq;
>
> diff --git a/net/mac80211/mesh.c b/net/mac80211/mesh.c
> index ca3af46..1430cdc 100644
> --- a/net/mac80211/mesh.c
> +++ b/net/mac80211/mesh.c
> @@ -574,7 +574,7 @@ static void ieee80211_mesh_rx_bcn_presp(struct ieee80211_sub_if_data *sdata,
> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? &elems);
>
> ? ? ? ?if (elems.ds_params && elems.ds_params_len == 1)
> - ? ? ? ? ? ? ? freq = ieee80211_channel_to_frequency(elems.ds_params[0]);
> + ? ? ? ? ? ? ? freq = ieee80211_channel_to_frequency(elems.ds_params[0], band);
> ? ? ? ?else
> ? ? ? ? ? ? ? ?freq = rx_status->freq;
>
> diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
> index 45fbb9e..33bd6d4 100644
> --- a/net/mac80211/mlme.c
> +++ b/net/mac80211/mlme.c
> @@ -176,7 +176,7 @@ static u32 ieee80211_enable_ht(struct ieee80211_sub_if_data *sdata,
>
> ? ? ? ?/* check that channel matches the right operating channel */
> ? ? ? ?if (local->hw.conf.channel->center_freq !=
> - ? ? ? ? ? ieee80211_channel_to_frequency(hti->control_chan))
> + ? ? ? ? ? ieee80211_channel_to_frequency(hti->control_chan, sband->band))
> ? ? ? ? ? ? ? ?enable_ht = false;
>
> ? ? ? ?if (enable_ht) {
> @@ -429,7 +429,8 @@ void ieee80211_sta_process_chanswitch(struct ieee80211_sub_if_data *sdata,
> ? ? ? ? ? ? ? ?container_of((void *)bss, struct cfg80211_bss, priv);
> ? ? ? ?struct ieee80211_channel *new_ch;
> ? ? ? ?struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
> - ? ? ? int new_freq = ieee80211_channel_to_frequency(sw_elem->new_ch_num);
> + ? ? ? int new_freq = ieee80211_channel_to_frequency(sw_elem->new_ch_num,
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? cbss->channel->band);
>
> ? ? ? ?ASSERT_MGD_MTX(ifmgd);
>
> @@ -1519,7 +1520,8 @@ static void ieee80211_rx_bss_info(struct ieee80211_sub_if_data *sdata,
> ? ? ? ?}
>
> ? ? ? ?if (elems->ds_params && elems->ds_params_len == 1)
> - ? ? ? ? ? ? ? freq = ieee80211_channel_to_frequency(elems->ds_params[0]);
> + ? ? ? ? ? ? ? freq = ieee80211_channel_to_frequency(elems->ds_params[0],
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? rx_status->band);
> ? ? ? ?else
> ? ? ? ? ? ? ? ?freq = rx_status->freq;
>
> diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c
> index fb274db..1ef73be 100644
> --- a/net/mac80211/scan.c
> +++ b/net/mac80211/scan.c
> @@ -196,7 +196,8 @@ ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
> ? ? ? ?ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
>
> ? ? ? ?if (elems.ds_params && elems.ds_params_len == 1)
> - ? ? ? ? ? ? ? freq = ieee80211_channel_to_frequency(elems.ds_params[0]);
> + ? ? ? ? ? ? ? freq = ieee80211_channel_to_frequency(elems.ds_params[0],
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? rx_status->band);
> ? ? ? ?else
> ? ? ? ? ? ? ? ?freq = rx_status->freq;
>
> diff --git a/net/wireless/reg.c b/net/wireless/reg.c
> index 37693b6..c565689 100644
> --- a/net/wireless/reg.c
> +++ b/net/wireless/reg.c
> @@ -1801,9 +1801,9 @@ void regulatory_hint_disconnect(void)
>
> ?static bool freq_is_chan_12_13_14(u16 freq)
> ?{
> - ? ? ? if (freq == ieee80211_channel_to_frequency(12) ||
> - ? ? ? ? ? freq == ieee80211_channel_to_frequency(13) ||
> - ? ? ? ? ? freq == ieee80211_channel_to_frequency(14))
> + ? ? ? if (freq == ieee80211_channel_to_frequency(12, IEEE80211_BAND_2GHZ) ||
> + ? ? ? ? ? freq == ieee80211_channel_to_frequency(13, IEEE80211_BAND_2GHZ) ||
> + ? ? ? ? ? freq == ieee80211_channel_to_frequency(14, IEEE80211_BAND_2GHZ))
> ? ? ? ? ? ? ? ?return true;
> ? ? ? ?return false;
> ?}
> diff --git a/net/wireless/util.c b/net/wireless/util.c
> index 7620ae2..4ed065d 100644
> --- a/net/wireless/util.c
> +++ b/net/wireless/util.c
> @@ -29,29 +29,37 @@ ieee80211_get_response_rate(struct ieee80211_supported_band *sband,
> ?}
> ?EXPORT_SYMBOL(ieee80211_get_response_rate);
>
> -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);
>
> diff --git a/net/wireless/wext-compat.c b/net/wireless/wext-compat.c
> index 3e5dbd4..7f1f4ec 100644
> --- a/net/wireless/wext-compat.c
> +++ b/net/wireless/wext-compat.c
> @@ -267,9 +267,12 @@ int cfg80211_wext_freq(struct wiphy *wiphy, struct iw_freq *freq)
> ? ? ? ? * -EINVAL for impossible things.
> ? ? ? ? */
> ? ? ? ?if (freq->e == 0) {
> + ? ? ? ? ? ? ? enum ieee80211_band band = IEEE80211_BAND_2GHZ;
> ? ? ? ? ? ? ? ?if (freq->m < 0)
> ? ? ? ? ? ? ? ? ? ? ? ?return 0;
> - ? ? ? ? ? ? ? return ieee80211_channel_to_frequency(freq->m);
> + ? ? ? ? ? ? ? if (freq->m > 14)
> + ? ? ? ? ? ? ? ? ? ? ? band = IEEE80211_BAND_5GHZ;
> + ? ? ? ? ? ? ? return ieee80211_channel_to_frequency(freq->m, band);
> ? ? ? ?} else {
> ? ? ? ? ? ? ? ?int i, div = 1000000;
> ? ? ? ? ? ? ? ?for (i = 0; i < freq->e; i++)


Do all drivers still build with this patch?  I applied the previous
RFC version of this patch to a late-December cut of compat-wireless,
and had to touch the receive-handling code in a half-dozen or so
drivers due to the API changes.

-Brian