drivers/staging/brcm80211/util/bcmwifi.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 <linux/ctype.h>
  17 #include <linux/kernel.h>
  18 #include <linux/module.h>
  19 #include <bcmdefs.h>
  20 #include <bcmutils.h>
  21 #include <bcmwifi.h>
  22
  23 /*
  24  * Verify the chanspec is using a legal set of parameters, i.e. that the
  25  * chanspec specified a band, bw, ctl_sb and channel and that the
  26  * combination could be legal given any set of circumstances.
  27  * RETURNS: true is the chanspec is malformed, false if it looks good.
  28  */
  29 bool bcm_chspec_malformed(chanspec_t chanspec)
  30 {
  31         /* must be 2G or 5G band */
  32         if (!CHSPEC_IS5G(chanspec) && !CHSPEC_IS2G(chanspec))
  33                 return true;
  34         /* must be 20 or 40 bandwidth */
  35         if (!CHSPEC_IS40(chanspec) && !CHSPEC_IS20(chanspec))
  36                 return true;
  37
  38         /* 20MHZ b/w must have no ctl sb, 40 must have a ctl sb */
  39         if (CHSPEC_IS20(chanspec)) {
  40                 if (!CHSPEC_SB_NONE(chanspec))
  41                         return true;
  42         } else {
  43                 if (!CHSPEC_SB_UPPER(chanspec) && !CHSPEC_SB_LOWER(chanspec))
  44                         return true;
  45         }
  46
  47         return false;
  48 }
  49 EXPORT_SYMBOL(bcm_chspec_malformed);
  50
  51 /*
  52  * This function returns the channel number that control traffic is being sent on, for legacy
  53  * channels this is just the channel number, for 40MHZ channels it is the upper or lowre 20MHZ
  54  * sideband depending on the chanspec selected
  55  */
  56 u8 bcm_chspec_ctlchan(chanspec_t chspec)
  57 {
  58         u8 ctl_chan;
  59
  60         /* Is there a sideband ? */
  61         if (CHSPEC_CTL_SB(chspec) == WL_CHANSPEC_CTL_SB_NONE) {
  62                 return CHSPEC_CHANNEL(chspec);
  63         } else {
  64                 /* we only support 40MHZ with sidebands */
  65                 /* chanspec channel holds the centre frequency, use that and the
  66                  * side band information to reconstruct the control channel number
  67                  */
  68                 if (CHSPEC_CTL_SB(chspec) == WL_CHANSPEC_CTL_SB_UPPER) {
  69                         /* control chan is the upper 20 MHZ SB of the 40MHZ channel */
  70                         ctl_chan = UPPER_20_SB(CHSPEC_CHANNEL(chspec));
  71                 } else {
  72                         /* control chan is the lower 20 MHZ SB of the 40MHZ channel */
  73                         ctl_chan = LOWER_20_SB(CHSPEC_CHANNEL(chspec));
  74                 }
  75         }
  76
  77         return ctl_chan;
  78 }
  79 EXPORT_SYMBOL(bcm_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 bcm_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(bcm_mhz2channel);
 137