drivers/net/wireless/brcm80211/brcmutil/wifi.c

/*
 * Copyright (c) 2010 Broadcom Corporation
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
#include <brcmu_wifi.h>

/*
 * Verify the chanspec is using a legal set of parameters, i.e. that the
 * chanspec specified a band, bw, ctl_sb and channel and that the
 * combination could be legal given any set of circumstances.
 * RETURNS: true is the chanspec is malformed, false if it looks good.
 */
bool brcmu_chspec_malformed(u16 chanspec)
{
	/* must be 2G or 5G band */
	if (!CHSPEC_IS5G(chanspec) && !CHSPEC_IS2G(chanspec))
		return true;
	/* must be 20 or 40 bandwidth */
	if (!CHSPEC_IS40(chanspec) && !CHSPEC_IS20(chanspec))
		return true;

	/* 20MHZ b/w must have no ctl sb, 40 must have a ctl sb */
	if (CHSPEC_IS20(chanspec)) {
		if (!CHSPEC_SB_NONE(chanspec))
			return true;
	} else if (!CHSPEC_SB_UPPER(chanspec) && !CHSPEC_SB_LOWER(chanspec)) {
		return true;
	}

	return false;
}
EXPORT_SYMBOL(brcmu_chspec_malformed);

/*
 * This function returns the channel number that control traffic is being sent
 * on, for legacy channels this is just the channel number, for 40MHZ channels
 * it is the upper or lower 20MHZ sideband depending on the chanspec selected.
 */
u8 brcmu_chspec_ctlchan(u16 chspec)
{
	u8 ctl_chan;

	/* Is there a sideband ? */
	if (CHSPEC_CTL_SB(chspec) == WL_CHANSPEC_CTL_SB_NONE) {
		return CHSPEC_CHANNEL(chspec);
	} else {
		/*
		 * we only support 40MHZ with sidebands. chanspec channel holds
		 * the centre frequency, use that and the side band information
		 * to reconstruct the control channel number
		 */
		if (CHSPEC_CTL_SB(chspec) == WL_CHANSPEC_CTL_SB_UPPER)
			/*
			 * control chan is the upper 20 MHZ SB of the
			 * 40MHZ channel
			 */
			ctl_chan = upper_20_sb(CHSPEC_CHANNEL(chspec));
		else
			/*
			 * control chan is the lower 20 MHZ SB of the
			 * 40MHZ channel
			 */
			ctl_chan = lower_20_sb(CHSPEC_CHANNEL(chspec));
	}

	return ctl_chan;
}
EXPORT_SYMBOL(brcmu_chspec_ctlchan);

/*
 * Return the channel number for a given frequency and base frequency.
 * The returned channel number is relative to the given base frequency.
 * If the given base frequency is zero, a base frequency of 5 GHz is assumed for
 * frequencies from 5 - 6 GHz, and 2.407 GHz is assumed for 2.4 - 2.5 GHz.
 *
 * Frequency is specified in MHz.
 * The base frequency is specified as (start_factor * 500 kHz).
 * Constants WF_CHAN_FACTOR_2_4_G, WF_CHAN_FACTOR_5_G are defined for
 * 2.4 GHz and 5 GHz bands.
 *
 * The returned channel will be in the range [1, 14] in the 2.4 GHz band
 * and [0, 200] otherwise.
 * -1 is returned if the start_factor is WF_CHAN_FACTOR_2_4_G and the
 * frequency is not a 2.4 GHz channel, or if the frequency is not and even
 * multiple of 5 MHz from the base frequency to the base plus 1 GHz.
 *
 * Reference 802.11 REVma, section 17.3.8.3, and 802.11B section 18.4.6.2
 */
int brcmu_mhz2channel(uint freq, uint start_factor)
{
	int ch = -1;
	uint base;
	int offset;

	/* take the default channel start frequency */
	if (start_factor == 0) {
		if (freq >= 2400 && freq <= 2500)
			start_factor = WF_CHAN_FACTOR_2_4_G;
		else if (freq >= 5000 && freq <= 6000)
			start_factor = WF_CHAN_FACTOR_5_G;
	}

	if (freq == 2484 && start_factor == WF_CHAN_FACTOR_2_4_G)
		return 14;

	base = start_factor / 2;

	/* check that the frequency is in 1GHz range of the base */
	if ((freq < base) || (freq > base + 1000))
		return -1;

	offset = freq - base;
	ch = offset / 5;

	/* check that frequency is a 5MHz multiple from the base */
	if (offset != (ch * 5))
		return -1;

	/* restricted channel range check for 2.4G */
	if (start_factor == WF_CHAN_FACTOR_2_4_G && (ch < 1 || ch > 13))
		return -1;

	return ch;
}
EXPORT_SYMBOL(brcmu_mhz2channel);