drivers/staging/brcm80211/brcmutil/wifi.c

   1 /*
   2  * Copyright (c) 2010 Broadcom Corporation
   3  *
   4  * Permission to use, copy, modify, and/or distribute this software for any
   5  * purpose with or without fee is hereby granted, provided that the above
   6  * copyright notice and this permission notice appear in all copies.
   7  *
   8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
  11  * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
  13  * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
  14  * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  15  */
  16 #include <brcmu_wifi.h>
  17
  18 /*
  19  * Verify the chanspec is using a legal set of parameters, i.e. that the
  20  * chanspec specified a band, bw, ctl_sb and channel and that the
  21  * combination could be legal given any set of circumstances.
  22  * RETURNS: true is the chanspec is malformed, false if it looks good.
  23  */
  24 bool brcmu_chspec_malformed(u16 chanspec)
  25 {
  26         /* must be 2G or 5G band */
  27         if (!CHSPEC_IS5G(chanspec) && !CHSPEC_IS2G(chanspec))
  28                 return true;
  29         /* must be 20 or 40 bandwidth */
  30         if (!CHSPEC_IS40(chanspec) && !CHSPEC_IS20(chanspec))
  31                 return true;
  32
  33         /* 20MHZ b/w must have no ctl sb, 40 must have a ctl sb */
  34         if (CHSPEC_IS20(chanspec)) {
  35                 if (!CHSPEC_SB_NONE(chanspec))
  36                         return true;
  37         } else if (!CHSPEC_SB_UPPER(chanspec) && !CHSPEC_SB_LOWER(chanspec)) {
  38                 return true;
  39         }
  40
  41         return false;
  42 }
  43 EXPORT_SYMBOL(brcmu_chspec_malformed);
  44
  45 /*
  46  * This function returns the channel number that control traffic is being sent
  47  * on, for legacy channels this is just the channel number, for 40MHZ channels
  48  * it is the upper or lower 20MHZ sideband depending on the chanspec selected.
  49  */
  50 u8 brcmu_chspec_ctlchan(u16 chspec)
  51 {
  52         u8 ctl_chan;
  53
  54         /* Is there a sideband ? */
  55         if (CHSPEC_CTL_SB(chspec) == WL_CHANSPEC_CTL_SB_NONE) {
  56                 return CHSPEC_CHANNEL(chspec);
  57         } else {
  58                 /*
  59                  * we only support 40MHZ with sidebands. chanspec channel holds
  60                  * the centre frequency, use that and the side band information
  61                  * to reconstruct the control channel number
  62                  */
  63                 if (CHSPEC_CTL_SB(chspec) == WL_CHANSPEC_CTL_SB_UPPER)
  64                         /*
  65                          * control chan is the upper 20 MHZ SB of the
  66                          * 40MHZ channel
  67                          */
  68                         ctl_chan = upper_20_sb(CHSPEC_CHANNEL(chspec));
  69                 else
  70                         /*
  71                          * control chan is the lower 20 MHZ SB of the
  72                          * 40MHZ channel
  73                          */
  74                         ctl_chan = lower_20_sb(CHSPEC_CHANNEL(chspec));
  75         }
  76
  77         return ctl_chan;
  78 }
  79 EXPORT_SYMBOL(brcmu_chspec_ctlchan);
  80
  81 /*
  82  * Return the channel number for a given frequency and base frequency.
  83  * The returned channel number is relative to the given base frequency.
  84  * If the given base frequency is zero, a base frequency of 5 GHz is assumed for
  85  * frequencies from 5 - 6 GHz, and 2.407 GHz is assumed for 2.4 - 2.5 GHz.
  86  *
  87  * Frequency is specified in MHz.
  88  * The base frequency is specified as (start_factor * 500 kHz).
  89  * Constants WF_CHAN_FACTOR_2_4_G, WF_CHAN_FACTOR_5_G are defined for
  90  * 2.4 GHz and 5 GHz bands.
  91  *
  92  * The returned channel will be in the range [1, 14] in the 2.4 GHz band
  93  * and [0, 200] otherwise.
  94  * -1 is returned if the start_factor is WF_CHAN_FACTOR_2_4_G and the
  95  * frequency is not a 2.4 GHz channel, or if the frequency is not and even
  96  * multiple of 5 MHz from the base frequency to the base plus 1 GHz.
  97  *
  98  * Reference 802.11 REVma, section 17.3.8.3, and 802.11B section 18.4.6.2
  99  */
 100 int brcmu_mhz2channel(uint freq, uint start_factor)
 101 {
 102         int ch = -1;
 103         uint base;
 104         int offset;
 105
 106         /* take the default channel start frequency */
 107         if (start_factor == 0) {
 108                 if (freq >= 2400 && freq <= 2500)
 109                         start_factor = WF_CHAN_FACTOR_2_4_G;
 110                 else if (freq >= 5000 && freq <= 6000)
 111                         start_factor = WF_CHAN_FACTOR_5_G;
 112         }
 113
 114         if (freq == 2484 && start_factor == WF_CHAN_FACTOR_2_4_G)
 115                 return 14;
 116
 117         base = start_factor / 2;
 118
 119         /* check that the frequency is in 1GHz range of the base */
 120         if ((freq < base) || (freq > base + 1000))
 121                 return -1;
 122
 123         offset = freq - base;
 124         ch = offset / 5;
 125
 126         /* check that frequency is a 5MHz multiple from the base */
 127         if (offset != (ch * 5))
 128                 return -1;
 129
 130         /* restricted channel range check for 2.4G */
 131         if (start_factor == WF_CHAN_FACTOR_2_4_G && (ch < 1 || ch > 13))
 132                 return -1;
 133
 134         return ch;
 135 }
 136 EXPORT_SYMBOL(brcmu_mhz2channel);