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(chanspec_t 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 {
  38                 if (!CHSPEC_SB_UPPER(chanspec) && !CHSPEC_SB_LOWER(chanspec))
  39                         return true;
  40         }
  41
  42         return false;
  43 }
  44 EXPORT_SYMBOL(brcmu_chspec_malformed);
  45
  46 /*
  47  * This function returns the channel number that control traffic is being sent on, for legacy
  48  * channels this is just the channel number, for 40MHZ channels it is the upper or lowre 20MHZ
  49  * sideband depending on the chanspec selected
  50  */
  51 u8 brcmu_chspec_ctlchan(chanspec_t chspec)
  52 {
  53         u8 ctl_chan;
  54
  55         /* Is there a sideband ? */
  56         if (CHSPEC_CTL_SB(chspec) == WL_CHANSPEC_CTL_SB_NONE) {
  57                 return CHSPEC_CHANNEL(chspec);
  58         } else {
  59                 /* we only support 40MHZ with sidebands */
  60                 /* chanspec channel holds the centre frequency, use that and the
  61                  * side band information to reconstruct the control channel number
  62                  */
  63                 if (CHSPEC_CTL_SB(chspec) == WL_CHANSPEC_CTL_SB_UPPER) {
  64                         /* control chan is the upper 20 MHZ SB of the 40MHZ channel */
  65                         ctl_chan = UPPER_20_SB(CHSPEC_CHANNEL(chspec));
  66                 } else {
  67                         /* control chan is the lower 20 MHZ SB of the 40MHZ channel */
  68                         ctl_chan = LOWER_20_SB(CHSPEC_CHANNEL(chspec));
  69                 }
  70         }
  71
  72         return ctl_chan;
  73 }
  74 EXPORT_SYMBOL(brcmu_chspec_ctlchan);
  75
  76 /*
  77  * Return the channel number for a given frequency and base frequency.
  78  * The returned channel number is relative to the given base frequency.
  79  * If the given base frequency is zero, a base frequency of 5 GHz is assumed for
  80  * frequencies from 5 - 6 GHz, and 2.407 GHz is assumed for 2.4 - 2.5 GHz.
  81  *
  82  * Frequency is specified in MHz.
  83  * The base frequency is specified as (start_factor * 500 kHz).
  84  * Constants WF_CHAN_FACTOR_2_4_G, WF_CHAN_FACTOR_5_G are defined for
  85  * 2.4 GHz and 5 GHz bands.
  86  *
  87  * The returned channel will be in the range [1, 14] in the 2.4 GHz band
  88  * and [0, 200] otherwise.
  89  * -1 is returned if the start_factor is WF_CHAN_FACTOR_2_4_G and the
  90  * frequency is not a 2.4 GHz channel, or if the frequency is not and even
  91  * multiple of 5 MHz from the base frequency to the base plus 1 GHz.
  92  *
  93  * Reference 802.11 REVma, section 17.3.8.3, and 802.11B section 18.4.6.2
  94  */
  95 int brcmu_mhz2channel(uint freq, uint start_factor)
  96 {
  97         int ch = -1;
  98         uint base;
  99         int offset;
 100
 101         /* take the default channel start frequency */
 102         if (start_factor == 0) {
 103                 if (freq >= 2400 && freq <= 2500)
 104                         start_factor = WF_CHAN_FACTOR_2_4_G;
 105                 else if (freq >= 5000 && freq <= 6000)
 106                         start_factor = WF_CHAN_FACTOR_5_G;
 107         }
 108
 109         if (freq == 2484 && start_factor == WF_CHAN_FACTOR_2_4_G)
 110                 return 14;
 111
 112         base = start_factor / 2;
 113
 114         /* check that the frequency is in 1GHz range of the base */
 115         if ((freq < base) || (freq > base + 1000))
 116                 return -1;
 117
 118         offset = freq - base;
 119         ch = offset / 5;
 120
 121         /* check that frequency is a 5MHz multiple from the base */
 122         if (offset != (ch * 5))
 123                 return -1;
 124
 125         /* restricted channel range check for 2.4G */
 126         if (start_factor == WF_CHAN_FACTOR_2_4_G && (ch < 1 || ch > 13))
 127                 return -1;
 128
 129         return ch;
 130 }
 131 EXPORT_SYMBOL(brcmu_mhz2channel);