/*
 * Copyright (c) 2009-2011 Atheros Communications Inc.
 *
 * 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.
 */

/*
 * Module for common driver code between ath9k and ath9k_htc
 */

#include <linux/export.h>
#include <linux/kernel.h>
#include <linux/module.h>

#include "common.h"

MODULE_AUTHOR("Atheros Communications");
MODULE_DESCRIPTION("Shared library for Atheros wireless 802.11n LAN cards.");
MODULE_LICENSE("Dual BSD/GPL");

/* Assumes you've already done the endian to CPU conversion */
bool ath9k_cmn_rx_accept(struct ath_common *common,
                         struct ieee80211_hdr *hdr,
                         struct ieee80211_rx_status *rxs,
                         struct ath_rx_status *rx_stats,
                         bool *decrypt_error,
                         unsigned int rxfilter)
{
        struct ath_hw *ah = common->ah;
        bool is_mc, is_valid_tkip, strip_mic, mic_error;
        __le16 fc;

        fc = hdr->frame_control;

        is_mc = !!is_multicast_ether_addr(hdr->addr1);
        is_valid_tkip = rx_stats->rs_keyix != ATH9K_RXKEYIX_INVALID &&
                test_bit(rx_stats->rs_keyix, common->tkip_keymap);
        strip_mic = is_valid_tkip && ieee80211_is_data(fc) &&
                ieee80211_has_protected(fc) &&
                !(rx_stats->rs_status &
                (ATH9K_RXERR_DECRYPT | ATH9K_RXERR_CRC | ATH9K_RXERR_MIC |
                 ATH9K_RXERR_KEYMISS));

        /*
         * Key miss events are only relevant for pairwise keys where the
         * descriptor does contain a valid key index. This has been observed
         * mostly with CCMP encryption.
         */
        if (rx_stats->rs_keyix == ATH9K_RXKEYIX_INVALID ||
            !test_bit(rx_stats->rs_keyix, common->ccmp_keymap))
                rx_stats->rs_status &= ~ATH9K_RXERR_KEYMISS;

        mic_error = is_valid_tkip && !ieee80211_is_ctl(fc) &&
                !ieee80211_has_morefrags(fc) &&
                !(le16_to_cpu(hdr->seq_ctrl) & IEEE80211_SCTL_FRAG) &&
                (rx_stats->rs_status & ATH9K_RXERR_MIC);

        /*
         * The rx_stats->rs_status will not be set until the end of the
         * chained descriptors so it can be ignored if rs_more is set. The
         * rs_more will be false at the last element of the chained
         * descriptors.
         */
        if (rx_stats->rs_status != 0) {
                u8 status_mask;

                if (rx_stats->rs_status & ATH9K_RXERR_CRC) {
                        rxs->flag |= RX_FLAG_FAILED_FCS_CRC;
                        mic_error = false;
                }

                if ((rx_stats->rs_status & ATH9K_RXERR_DECRYPT) ||
                    (!is_mc && (rx_stats->rs_status & ATH9K_RXERR_KEYMISS))) {
                        *decrypt_error = true;
                        mic_error = false;
                }


                /*
                 * Reject error frames with the exception of
                 * decryption and MIC failures. For monitor mode,
                 * we also ignore the CRC error.
                 */
                status_mask = ATH9K_RXERR_DECRYPT | ATH9K_RXERR_MIC |
                              ATH9K_RXERR_KEYMISS;

                if (ah->is_monitoring && (rxfilter & FIF_FCSFAIL))
                        status_mask |= ATH9K_RXERR_CRC;

                if (rx_stats->rs_status & ~status_mask)
                        return false;
        }

        /*
         * For unicast frames the MIC error bit can have false positives,
         * so all MIC error reports need to be validated in software.
         * False negatives are not common, so skip software verification
         * if the hardware considers the MIC valid.
         */
        if (strip_mic)
                rxs->flag |= RX_FLAG_MMIC_STRIPPED;
        else if (is_mc && mic_error)
                rxs->flag |= RX_FLAG_MMIC_ERROR;

        return true;
}
EXPORT_SYMBOL(ath9k_cmn_rx_accept);

void ath9k_cmn_rx_skb_postprocess(struct ath_common *common,
                                  struct sk_buff *skb,
                                  struct ath_rx_status *rx_stats,
                                  struct ieee80211_rx_status *rxs,
                                  bool decrypt_error)
{
        struct ath_hw *ah = common->ah;
        struct ieee80211_hdr *hdr;
        int hdrlen, padpos, padsize;
        u8 keyix;
        __le16 fc;

        /* see if any padding is done by the hw and remove it */
        hdr = (struct ieee80211_hdr *) skb->data;
        hdrlen = ieee80211_get_hdrlen_from_skb(skb);
        fc = hdr->frame_control;
        padpos = ieee80211_hdrlen(fc);

        /* The MAC header is padded to have 32-bit boundary if the
         * packet payload is non-zero. The general calculation for
         * padsize would take into account odd header lengths:
         * padsize = (4 - padpos % 4) % 4; However, since only
         * even-length headers are used, padding can only be 0 or 2
         * bytes and we can optimize this a bit. In addition, we must
         * not try to remove padding from short control frames that do
         * not have payload. */
        padsize = padpos & 3;
        if (padsize && skb->len>=padpos+padsize+FCS_LEN) {
                memmove(skb->data + padsize, skb->data, padpos);
                skb_pull(skb, padsize);
        }

        keyix = rx_stats->rs_keyix;

        if (!(keyix == ATH9K_RXKEYIX_INVALID) && !decrypt_error &&
            ieee80211_has_protected(fc)) {
                rxs->flag |= RX_FLAG_DECRYPTED;
        } else if (ieee80211_has_protected(fc)
                   && !decrypt_error && skb->len >= hdrlen + 4) {
                keyix = skb->data[hdrlen + 3] >> 6;

                if (test_bit(keyix, common->keymap))
                        rxs->flag |= RX_FLAG_DECRYPTED;
        }
        if (ah->sw_mgmt_crypto_rx &&
            (rxs->flag & RX_FLAG_DECRYPTED) &&
            ieee80211_is_mgmt(fc))
                /* Use software decrypt for management frames. */
                rxs->flag &= ~RX_FLAG_DECRYPTED;
}
EXPORT_SYMBOL(ath9k_cmn_rx_skb_postprocess);

int ath9k_cmn_process_rate(struct ath_common *common,
                           struct ieee80211_hw *hw,
                           struct ath_rx_status *rx_stats,
                           struct ieee80211_rx_status *rxs)
{
        struct ieee80211_supported_band *sband;
        enum nl80211_band band;
        unsigned int i = 0;
        struct ath_hw *ah = common->ah;

        band = ah->curchan->chan->band;
        sband = hw->wiphy->bands[band];

        if (IS_CHAN_QUARTER_RATE(ah->curchan))
                rxs->bw = RATE_INFO_BW_5;
        else if (IS_CHAN_HALF_RATE(ah->curchan))
                rxs->bw = RATE_INFO_BW_10;

        if (rx_stats->rs_rate & 0x80) {
                /* HT rate */
                rxs->encoding = RX_ENC_HT;
                rxs->enc_flags |= rx_stats->enc_flags;
                rxs->bw = rx_stats->bw;
                rxs->rate_idx = rx_stats->rs_rate & 0x7f;
                return 0;
        }

        for (i = 0; i < sband->n_bitrates; i++) {
                if (sband->bitrates[i].hw_value == rx_stats->rs_rate) {
                        rxs->rate_idx = i;
                        return 0;
                }
                if (sband->bitrates[i].hw_value_short == rx_stats->rs_rate) {
                        rxs->enc_flags |= RX_ENC_FLAG_SHORTPRE;
                        rxs->rate_idx = i;
                        return 0;
                }
        }

        return -EINVAL;
}
EXPORT_SYMBOL(ath9k_cmn_process_rate);

void ath9k_cmn_process_rssi(struct ath_common *common,
                            struct ieee80211_hw *hw,
                            struct ath_rx_status *rx_stats,
                            struct ieee80211_rx_status *rxs)
{
        struct ath_hw *ah = common->ah;
        int last_rssi;
        int rssi = rx_stats->rs_rssi;
        int i, j;

        /*
         * RSSI is not available for subframes in an A-MPDU.
         */
        if (rx_stats->rs_moreaggr) {
                rxs->flag |= RX_FLAG_NO_SIGNAL_VAL;
                return;
        }

        /*
         * Check if the RSSI for the last subframe in an A-MPDU
         * or an unaggregated frame is valid.
         */
        if (rx_stats->rs_rssi == ATH9K_RSSI_BAD) {
                rxs->flag |= RX_FLAG_NO_SIGNAL_VAL;
                return;
        }

        for (i = 0, j = 0; i < ARRAY_SIZE(rx_stats->rs_rssi_ctl); i++) {
                s8 rssi;

                if (!(ah->rxchainmask & BIT(i)))
                        continue;

                rssi = rx_stats->rs_rssi_ctl[i];
                if (rssi != ATH9K_RSSI_BAD) {
                    rxs->chains |= BIT(j);
                    rxs->chain_signal[j] = ah->noise + rssi;
                }
                j++;
        }

        /*
         * Update Beacon RSSI, this is used by ANI.
         */
        if (rx_stats->is_mybeacon &&
            ((ah->opmode == NL80211_IFTYPE_STATION) ||
             (ah->opmode == NL80211_IFTYPE_ADHOC))) {
                ATH_RSSI_LPF(common->last_rssi, rx_stats->rs_rssi);
                last_rssi = common->last_rssi;

                if (likely(last_rssi != ATH_RSSI_DUMMY_MARKER))
                        rssi = ATH_EP_RND(last_rssi, ATH_RSSI_EP_MULTIPLIER);
                if (rssi < 0)
                        rssi = 0;

                ah->stats.avgbrssi = rssi;
        }

        rxs->signal = ah->noise + rx_stats->rs_rssi;
}
EXPORT_SYMBOL(ath9k_cmn_process_rssi);

int ath9k_cmn_get_hw_crypto_keytype(struct sk_buff *skb)
{
        struct ieee80211_tx_info *tx_info = IEEE80211_SKB_CB(skb);

        if (tx_info->control.hw_key) {
                switch (tx_info->control.hw_key->cipher) {
                case WLAN_CIPHER_SUITE_WEP40:
                case WLAN_CIPHER_SUITE_WEP104:
                        return ATH9K_KEY_TYPE_WEP;
                case WLAN_CIPHER_SUITE_TKIP:
                        return ATH9K_KEY_TYPE_TKIP;
                case WLAN_CIPHER_SUITE_CCMP:
                        return ATH9K_KEY_TYPE_AES;
                default:
                        break;
                }
        }

        return ATH9K_KEY_TYPE_CLEAR;
}
EXPORT_SYMBOL(ath9k_cmn_get_hw_crypto_keytype);

/*
 * Update internal channel flags.
 */
static void ath9k_cmn_update_ichannel(struct ath9k_channel *ichan,
                                      struct cfg80211_chan_def *chandef)
{
        struct ieee80211_channel *chan = chandef->chan;
        u16 flags = 0;

        ichan->channel = chan->center_freq;
        ichan->chan = chan;

        if (chan->band == NL80211_BAND_5GHZ)
                flags |= CHANNEL_5GHZ;

        switch (chandef->width) {
        case NL80211_CHAN_WIDTH_5:
                flags |= CHANNEL_QUARTER;
                break;
        case NL80211_CHAN_WIDTH_10:
                flags |= CHANNEL_HALF;
                break;
        case NL80211_CHAN_WIDTH_20_NOHT:
                break;
        case NL80211_CHAN_WIDTH_20:
                flags |= CHANNEL_HT;
                break;
        case NL80211_CHAN_WIDTH_40:
                if (chandef->center_freq1 > chandef->chan->center_freq)
                        flags |= CHANNEL_HT40PLUS | CHANNEL_HT;
                else
                        flags |= CHANNEL_HT40MINUS | CHANNEL_HT;
                break;
        default:
                WARN_ON(1);
        }

        ichan->channelFlags = flags;
}

/*
 * Get the internal channel reference.
 */
struct ath9k_channel *ath9k_cmn_get_channel(struct ieee80211_hw *hw,
                                            struct ath_hw *ah,
                                            struct cfg80211_chan_def *chandef)
{
        struct ieee80211_channel *curchan = chandef->chan;
        struct ath9k_channel *channel;

        channel = &ah->channels[curchan->hw_value];
        ath9k_cmn_update_ichannel(channel, chandef);

        return channel;
}
EXPORT_SYMBOL(ath9k_cmn_get_channel);

int ath9k_cmn_count_streams(unsigned int chainmask, int max)
{
        int streams = 0;

        do {
                if (++streams == max)
                        break;
        } while ((chainmask = chainmask & (chainmask - 1)));

        return streams;
}
EXPORT_SYMBOL(ath9k_cmn_count_streams);

void ath9k_cmn_update_txpow(struct ath_hw *ah, u16 cur_txpow,
                            u16 new_txpow, u16 *txpower)
{
        struct ath_regulatory *reg = ath9k_hw_regulatory(ah);

        if (ah->curchan && reg->power_limit != new_txpow)
                ath9k_hw_set_txpowerlimit(ah, new_txpow, false);

        /* read back in case value is clamped */
        *txpower = reg->max_power_level;
}
EXPORT_SYMBOL(ath9k_cmn_update_txpow);

void ath9k_cmn_init_crypto(struct ath_hw *ah)
{
        struct ath_common *common = ath9k_hw_common(ah);
        int i = 0;

        /* Get the hardware key cache size. */
        common->keymax = AR_KEYTABLE_SIZE;

        /*
         * Check whether the separate key cache entries
         * are required to handle both tx+rx MIC keys.
         * With split mic keys the number of stations is limited
         * to 27 otherwise 59.
         */
        if (ah->misc_mode & AR_PCU_MIC_NEW_LOC_ENA)
                common->crypt_caps |= ATH_CRYPT_CAP_MIC_COMBINED;

        /*
         * Reset the key cache since some parts do not
         * reset the contents on initial power up.
         */
        for (i = 0; i < common->keymax; i++)
                ath_hw_keyreset(common, (u16) i);
}
EXPORT_SYMBOL(ath9k_cmn_init_crypto);