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+/*
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+ * Copyright (c) 2009 Atheros Communications Inc.
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+ *
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+ * Permission to use, copy, modify, and/or distribute this software for any
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+ * purpose with or without fee is hereby granted, provided that the above
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+ * copyright notice and this permission notice appear in all copies.
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+ *
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+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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+ */
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+
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+/*
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+ * Module for common driver code between ath9k and ath9k_htc
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+ */
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+
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+#include <linux/kernel.h>
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+#include <linux/module.h>
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+
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+#include "common.h"
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+
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+MODULE_AUTHOR("Atheros Communications");
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+MODULE_DESCRIPTION("Shared library for Atheros wireless 802.11n LAN cards.");
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+MODULE_LICENSE("Dual BSD/GPL");
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+
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+/* Common RX processing */
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+
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+/* Assumes you've already done the endian to CPU conversion */
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+static bool ath9k_rx_accept(struct ath_common *common,
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+ struct sk_buff *skb,
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+ struct ieee80211_rx_status *rxs,
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+ struct ath_rx_status *rx_stats,
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+ bool *decrypt_error)
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+{
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+ struct ath_hw *ah = common->ah;
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+ struct ieee80211_hdr *hdr;
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+ __le16 fc;
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+
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+ hdr = (struct ieee80211_hdr *) skb->data;
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+ fc = hdr->frame_control;
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+
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+ if (!rx_stats->rs_datalen)
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+ return false;
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+ /*
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+ * rs_status follows rs_datalen so if rs_datalen is too large
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+ * we can take a hint that hardware corrupted it, so ignore
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+ * those frames.
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+ */
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+ if (rx_stats->rs_datalen > common->rx_bufsize)
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+ return false;
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+
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+ if (rx_stats->rs_more) {
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+ /*
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+ * Frame spans multiple descriptors; this cannot happen yet
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+ * as we don't support jumbograms. If not in monitor mode,
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+ * discard the frame. Enable this if you want to see
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+ * error frames in Monitor mode.
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+ */
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+ if (ah->opmode != NL80211_IFTYPE_MONITOR)
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+ return false;
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+ } else if (rx_stats->rs_status != 0) {
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+ if (rx_stats->rs_status & ATH9K_RXERR_CRC)
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+ rxs->flag |= RX_FLAG_FAILED_FCS_CRC;
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+ if (rx_stats->rs_status & ATH9K_RXERR_PHY)
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+ return false;
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+
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+ if (rx_stats->rs_status & ATH9K_RXERR_DECRYPT) {
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+ *decrypt_error = true;
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+ } else if (rx_stats->rs_status & ATH9K_RXERR_MIC) {
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+ if (ieee80211_is_ctl(fc))
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+ /*
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+ * Sometimes, we get invalid
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+ * MIC failures on valid control frames.
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+ * Remove these mic errors.
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+ */
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+ rx_stats->rs_status &= ~ATH9K_RXERR_MIC;
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+ else
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+ rxs->flag |= RX_FLAG_MMIC_ERROR;
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+ }
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+ /*
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+ * Reject error frames with the exception of
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+ * decryption and MIC failures. For monitor mode,
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+ * we also ignore the CRC error.
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+ */
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+ if (ah->opmode == NL80211_IFTYPE_MONITOR) {
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+ if (rx_stats->rs_status &
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+ ~(ATH9K_RXERR_DECRYPT | ATH9K_RXERR_MIC |
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+ ATH9K_RXERR_CRC))
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+ return false;
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+ } else {
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+ if (rx_stats->rs_status &
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+ ~(ATH9K_RXERR_DECRYPT | ATH9K_RXERR_MIC)) {
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+ return false;
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+ }
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+ }
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+ }
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+ return true;
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+}
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+
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+static u8 ath9k_process_rate(struct ath_common *common,
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+ struct ieee80211_hw *hw,
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+ struct ath_rx_status *rx_stats,
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+ struct ieee80211_rx_status *rxs,
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+ struct sk_buff *skb)
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+{
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+ struct ieee80211_supported_band *sband;
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+ enum ieee80211_band band;
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+ unsigned int i = 0;
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+
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+ band = hw->conf.channel->band;
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+ sband = hw->wiphy->bands[band];
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+
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+ if (rx_stats->rs_rate & 0x80) {
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+ /* HT rate */
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+ rxs->flag |= RX_FLAG_HT;
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+ if (rx_stats->rs_flags & ATH9K_RX_2040)
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+ rxs->flag |= RX_FLAG_40MHZ;
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+ if (rx_stats->rs_flags & ATH9K_RX_GI)
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+ rxs->flag |= RX_FLAG_SHORT_GI;
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+ return rx_stats->rs_rate & 0x7f;
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+ }
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+
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+ for (i = 0; i < sband->n_bitrates; i++) {
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+ if (sband->bitrates[i].hw_value == rx_stats->rs_rate)
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+ return i;
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+ if (sband->bitrates[i].hw_value_short == rx_stats->rs_rate) {
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+ rxs->flag |= RX_FLAG_SHORTPRE;
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+ return i;
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+ }
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+ }
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+
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+ /* No valid hardware bitrate found -- we should not get here */
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+ ath_print(common, ATH_DBG_XMIT, "unsupported hw bitrate detected "
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+ "0x%02x using 1 Mbit\n", rx_stats->rs_rate);
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+ if ((common->debug_mask & ATH_DBG_XMIT))
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+ print_hex_dump_bytes("", DUMP_PREFIX_NONE, skb->data, skb->len);
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+
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+ return 0;
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+}
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+
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+/*
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+ * Theory for reporting quality:
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+ *
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+ * At a hardware RSSI of 45 you will be able to use MCS 7 reliably.
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+ * At a hardware RSSI of 45 you will be able to use MCS 15 reliably.
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+ * At a hardware RSSI of 35 you should be able use 54 Mbps reliably.
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+ *
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+ * MCS 7 is the highets MCS index usable by a 1-stream device.
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+ * MCS 15 is the highest MCS index usable by a 2-stream device.
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+ *
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+ * All ath9k devices are either 1-stream or 2-stream.
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+ *
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+ * How many bars you see is derived from the qual reporting.
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+ *
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+ * A more elaborate scheme can be used here but it requires tables
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+ * of SNR/throughput for each possible mode used. For the MCS table
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+ * you can refer to the wireless wiki:
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+ *
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+ * http://wireless.kernel.org/en/developers/Documentation/ieee80211/802.11n
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+ *
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+ */
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+static int ath9k_compute_qual(struct ieee80211_hw *hw,
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+ struct ath_rx_status *rx_stats)
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+{
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+ int qual;
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+
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+ if (conf_is_ht(&hw->conf))
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+ qual = rx_stats->rs_rssi * 100 / 45;
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+ else
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+ qual = rx_stats->rs_rssi * 100 / 35;
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+
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+ /*
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+ * rssi can be more than 45 though, anything above that
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+ * should be considered at 100%
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+ */
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+ if (qual > 100)
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+ qual = 100;
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+
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+ return qual;
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+}
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+
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+static void ath9k_process_rssi(struct ath_common *common,
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+ struct ieee80211_hw *hw,
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+ struct sk_buff *skb,
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+ struct ath_rx_status *rx_stats)
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+{
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+ struct ath_hw *ah = common->ah;
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+ struct ieee80211_sta *sta;
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+ struct ieee80211_hdr *hdr;
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+ struct ath_node *an;
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+ int last_rssi = ATH_RSSI_DUMMY_MARKER;
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+ __le16 fc;
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+
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+ hdr = (struct ieee80211_hdr *)skb->data;
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+ fc = hdr->frame_control;
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+
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+ rcu_read_lock();
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+ /*
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+ * XXX: use ieee80211_find_sta! This requires quite a bit of work
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+ * under the current ath9k virtual wiphy implementation as we have
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+ * no way of tying a vif to wiphy. Typically vifs are attached to
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+ * at least one sdata of a wiphy on mac80211 but with ath9k virtual
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+ * wiphy you'd have to iterate over every wiphy and each sdata.
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+ */
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+ sta = ieee80211_find_sta_by_hw(hw, hdr->addr2);
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+ if (sta) {
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+ an = (struct ath_node *) sta->drv_priv;
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+ if (rx_stats->rs_rssi != ATH9K_RSSI_BAD &&
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+ !rx_stats->rs_moreaggr)
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+ ATH_RSSI_LPF(an->last_rssi, rx_stats->rs_rssi);
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+ last_rssi = an->last_rssi;
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+ }
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+ rcu_read_unlock();
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+
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+ if (likely(last_rssi != ATH_RSSI_DUMMY_MARKER))
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+ rx_stats->rs_rssi = ATH_EP_RND(last_rssi,
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+ ATH_RSSI_EP_MULTIPLIER);
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+ if (rx_stats->rs_rssi < 0)
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+ rx_stats->rs_rssi = 0;
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+ else if (rx_stats->rs_rssi > 127)
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+ rx_stats->rs_rssi = 127;
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+
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+ /* Update Beacon RSSI, this is used by ANI. */
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+ if (ieee80211_is_beacon(fc))
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+ ah->stats.avgbrssi = rx_stats->rs_rssi;
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+}
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+
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+/*
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+ * For Decrypt or Demic errors, we only mark packet status here and always push
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+ * up the frame up to let mac80211 handle the actual error case, be it no
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+ * decryption key or real decryption error. This let us keep statistics there.
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+ */
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+int ath9k_cmn_rx_skb_preprocess(struct ath_common *common,
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+ struct ieee80211_hw *hw,
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+ struct sk_buff *skb,
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+ struct ath_rx_status *rx_stats,
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+ struct ieee80211_rx_status *rx_status,
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+ bool *decrypt_error)
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+{
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+ struct ath_hw *ah = common->ah;
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+
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+ if (!ath9k_rx_accept(common, skb, rx_status, rx_stats, decrypt_error))
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+ return -EINVAL;
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+
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+ ath9k_process_rssi(common, hw, skb, rx_stats);
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+
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+ rx_status->rate_idx = ath9k_process_rate(common, hw,
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+ rx_stats, rx_status, skb);
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+ rx_status->mactime = ath9k_hw_extend_tsf(ah, rx_stats->rs_tstamp);
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+ rx_status->band = hw->conf.channel->band;
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+ rx_status->freq = hw->conf.channel->center_freq;
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+ rx_status->noise = common->ani.noise_floor;
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+ rx_status->signal = ATH_DEFAULT_NOISE_FLOOR + rx_stats->rs_rssi;
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+ rx_status->antenna = rx_stats->rs_antenna;
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+ rx_status->qual = ath9k_compute_qual(hw, rx_stats);
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+ rx_status->flag |= RX_FLAG_TSFT;
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+
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+ return 0;
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+}
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+EXPORT_SYMBOL(ath9k_cmn_rx_skb_preprocess);
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+
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+void ath9k_cmn_rx_skb_postprocess(struct ath_common *common,
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+ struct sk_buff *skb,
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+ struct ath_rx_status *rx_stats,
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+ struct ieee80211_rx_status *rxs,
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+ bool decrypt_error)
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+{
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+ struct ath_hw *ah = common->ah;
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+ struct ieee80211_hdr *hdr;
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+ int hdrlen, padsize;
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+ u8 keyix;
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+ __le16 fc;
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+
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+ /* see if any padding is done by the hw and remove it */
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+ hdr = (struct ieee80211_hdr *) skb->data;
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+ hdrlen = ieee80211_get_hdrlen_from_skb(skb);
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+ fc = hdr->frame_control;
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+
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+ /* The MAC header is padded to have 32-bit boundary if the
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+ * packet payload is non-zero. The general calculation for
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+ * padsize would take into account odd header lengths:
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+ * padsize = (4 - hdrlen % 4) % 4; However, since only
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+ * even-length headers are used, padding can only be 0 or 2
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+ * bytes and we can optimize this a bit. In addition, we must
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+ * not try to remove padding from short control frames that do
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+ * not have payload. */
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+ padsize = hdrlen & 3;
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+ if (padsize && hdrlen >= 24) {
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+ memmove(skb->data + padsize, skb->data, hdrlen);
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+ skb_pull(skb, padsize);
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+ }
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+
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+ keyix = rx_stats->rs_keyix;
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+
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+ if (!(keyix == ATH9K_RXKEYIX_INVALID) && !decrypt_error) {
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+ rxs->flag |= RX_FLAG_DECRYPTED;
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+ } else if (ieee80211_has_protected(fc)
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+ && !decrypt_error && skb->len >= hdrlen + 4) {
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+ keyix = skb->data[hdrlen + 3] >> 6;
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+
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+ if (test_bit(keyix, common->keymap))
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+ rxs->flag |= RX_FLAG_DECRYPTED;
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+ }
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+ if (ah->sw_mgmt_crypto &&
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+ (rxs->flag & RX_FLAG_DECRYPTED) &&
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+ ieee80211_is_mgmt(fc))
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+ /* Use software decrypt for management frames. */
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+ rxs->flag &= ~RX_FLAG_DECRYPTED;
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+}
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+EXPORT_SYMBOL(ath9k_cmn_rx_skb_postprocess);
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+
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+static int __init ath9k_cmn_init(void)
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+{
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+ return 0;
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+}
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+module_init(ath9k_cmn_init);
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+
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+static void __exit ath9k_cmn_exit(void)
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+{
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+ return;
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+}
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+module_exit(ath9k_cmn_exit);
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Luis R. Rodriguez