drivers/net/wireless/iwlwifi/mvm/rx.c

/******************************************************************************
 *
 * This file is provided under a dual BSD/GPLv2 license.  When using or
 * redistributing this file, you may do so under either license.
 *
 * GPL LICENSE SUMMARY
 *
 * Copyright(c) 2012 - 2013 Intel Corporation. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110,
 * USA
 *
 * The full GNU General Public License is included in this distribution
 * in the file called LICENSE.GPL.
 *
 * Contact Information:
 *  Intel Linux Wireless <ilw@linux.intel.com>
 * Intel Corporation, 5200 N.E. Elam Young Parkway, Hillsboro, OR 97124-6497
 *
 * BSD LICENSE
 *
 * Copyright(c) 2012 - 2013 Intel Corporation. All rights reserved.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *  * Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *  * Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *  * Neither the name Intel Corporation nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *****************************************************************************/
#include "iwl-trans.h"

#include "mvm.h"
#include "fw-api.h"

/*
 * iwl_mvm_rx_rx_phy_cmd - REPLY_RX_PHY_CMD handler
 *
 * Copies the phy information in mvm->last_phy_info, it will be used when the
 * actual data will come from the fw in the next packet.
 */
int iwl_mvm_rx_rx_phy_cmd(struct iwl_mvm *mvm, struct iwl_rx_cmd_buffer *rxb,
			  struct iwl_device_cmd *cmd)
{
	struct iwl_rx_packet *pkt = rxb_addr(rxb);

	memcpy(&mvm->last_phy_info, pkt->data, sizeof(mvm->last_phy_info));
	mvm->ampdu_ref++;
	return 0;
}

/*
 * iwl_mvm_pass_packet_to_mac80211 - builds the packet for mac80211
 *
 * Adds the rxb to a new skb and give it to mac80211
 */
static void iwl_mvm_pass_packet_to_mac80211(struct iwl_mvm *mvm,
					    struct ieee80211_hdr *hdr, u16 len,
					    u32 ampdu_status,
					    struct iwl_rx_cmd_buffer *rxb,
					    struct ieee80211_rx_status *stats)
{
	struct sk_buff *skb;
	unsigned int hdrlen, fraglen;

	/* Dont use dev_alloc_skb(), we'll have enough headroom once
	 * ieee80211_hdr pulled.
	 */
	skb = alloc_skb(128, GFP_ATOMIC);
	if (!skb) {
		IWL_ERR(mvm, "alloc_skb failed\n");
		return;
	}
	/* If frame is small enough to fit in skb->head, pull it completely.
	 * If not, only pull ieee80211_hdr so that splice() or TCP coalesce
	 * are more efficient.
	 */
	hdrlen = (len <= skb_tailroom(skb)) ? len : sizeof(*hdr);

	memcpy(skb_put(skb, hdrlen), hdr, hdrlen);
	fraglen = len - hdrlen;

	if (fraglen) {
		int offset = (void *)hdr + hdrlen -
			     rxb_addr(rxb) + rxb_offset(rxb);

		skb_add_rx_frag(skb, 0, rxb_steal_page(rxb), offset,
				fraglen, rxb->truesize);
	}

	memcpy(IEEE80211_SKB_RXCB(skb), stats, sizeof(*stats));

	ieee80211_rx(mvm->hw, skb);
}

/*
 * iwl_mvm_calc_rssi - calculate the rssi in dBm
 * @phy_info: the phy information for the coming packet
 */
static int iwl_mvm_calc_rssi(struct iwl_mvm *mvm,
			     struct iwl_rx_phy_info *phy_info)
{
	u32 rssi_a, rssi_b, rssi_c, max_rssi, agc_db;
	u32 val;

	/* Find max rssi among 3 possible receivers.
	 * These values are measured by the Digital Signal Processor (DSP).
	 * They should stay fairly constant even as the signal strength varies,
	 * if the radio's Automatic Gain Control (AGC) is working right.
	 * AGC value (see below) will provide the "interesting" info.
	 */
	val = le32_to_cpu(phy_info->non_cfg_phy[IWL_RX_INFO_RSSI_AB_IDX]);
	rssi_a = (val & IWL_OFDM_RSSI_INBAND_A_MSK) >> IWL_OFDM_RSSI_A_POS;
	rssi_b = (val & IWL_OFDM_RSSI_INBAND_B_MSK) >> IWL_OFDM_RSSI_B_POS;
	val = le32_to_cpu(phy_info->non_cfg_phy[IWL_RX_INFO_RSSI_C_IDX]);
	rssi_c = (val & IWL_OFDM_RSSI_INBAND_C_MSK) >> IWL_OFDM_RSSI_C_POS;

	val = le32_to_cpu(phy_info->non_cfg_phy[IWL_RX_INFO_AGC_IDX]);
	agc_db = (val & IWL_OFDM_AGC_DB_MSK) >> IWL_OFDM_AGC_DB_POS;

	max_rssi = max_t(u32, rssi_a, rssi_b);
	max_rssi = max_t(u32, max_rssi, rssi_c);

	IWL_DEBUG_STATS(mvm, "Rssi In A %d B %d C %d Max %d AGC dB %d\n",
			rssi_a, rssi_b, rssi_c, max_rssi, agc_db);

	/* dBm = max_rssi dB - agc dB - constant.
	 * Higher AGC (higher radio gain) means lower signal. */
	return max_rssi - agc_db - IWL_RSSI_OFFSET;
}

/*
 * iwl_mvm_set_mac80211_rx_flag - translate fw status to mac80211 format
 * @mvm: the mvm object
 * @hdr: 80211 header
 * @stats: status in mac80211's format
 * @rx_pkt_status: status coming from fw
 *
 * returns non 0 value if the packet should be dropped
 */
static u32 iwl_mvm_set_mac80211_rx_flag(struct iwl_mvm *mvm,
					struct ieee80211_hdr *hdr,
					struct ieee80211_rx_status *stats,
					u32 rx_pkt_status)
{
	if (!ieee80211_has_protected(hdr->frame_control) ||
	    (rx_pkt_status & RX_MPDU_RES_STATUS_SEC_ENC_MSK) ==
			     RX_MPDU_RES_STATUS_SEC_NO_ENC)
		return 0;

	/* packet was encrypted with unknown alg */
	if ((rx_pkt_status & RX_MPDU_RES_STATUS_SEC_ENC_MSK) ==
					RX_MPDU_RES_STATUS_SEC_ENC_ERR)
		return 0;

	switch (rx_pkt_status & RX_MPDU_RES_STATUS_SEC_ENC_MSK) {
	case RX_MPDU_RES_STATUS_SEC_CCM_ENC:
		/* alg is CCM: check MIC only */
		if (!(rx_pkt_status & RX_MPDU_RES_STATUS_MIC_OK))
			return -1;

		stats->flag |= RX_FLAG_DECRYPTED;
		IWL_DEBUG_WEP(mvm, "hw decrypted CCMP successfully\n");
		return 0;

	case RX_MPDU_RES_STATUS_SEC_TKIP_ENC:
		/* Don't drop the frame and decrypt it in SW */
		if (!(rx_pkt_status & RX_MPDU_RES_STATUS_TTAK_OK))
			return 0;
		/* fall through if TTAK OK */

	case RX_MPDU_RES_STATUS_SEC_WEP_ENC:
		if (!(rx_pkt_status & RX_MPDU_RES_STATUS_ICV_OK))
			return -1;

		stats->flag |= RX_FLAG_DECRYPTED;
		return 0;

	default:
		IWL_ERR(mvm, "Unhandled alg: 0x%x\n", rx_pkt_status);
	}

	return 0;
}

/*
 * iwl_mvm_rx_rx_mpdu - REPLY_RX_MPDU_CMD handler
 *
 * Handles the actual data of the Rx packet from the fw
 */
int iwl_mvm_rx_rx_mpdu(struct iwl_mvm *mvm, struct iwl_rx_cmd_buffer *rxb,
		       struct iwl_device_cmd *cmd)
{
	struct ieee80211_hdr *hdr;
	struct ieee80211_rx_status rx_status = {};
	struct iwl_rx_packet *pkt = rxb_addr(rxb);
	struct iwl_rx_phy_info *phy_info;
	struct iwl_rx_mpdu_res_start *rx_res;
	u32 len;
	u32 ampdu_status;
	u32 rate_n_flags;
	u32 rx_pkt_status;

	phy_info = &mvm->last_phy_info;
	rx_res = (struct iwl_rx_mpdu_res_start *)pkt->data;
	hdr = (struct ieee80211_hdr *)(pkt->data + sizeof(*rx_res));
	len = le16_to_cpu(rx_res->byte_count);
	rx_pkt_status = le32_to_cpup((__le32 *)
		(pkt->data + sizeof(*rx_res) + len));

	memset(&rx_status, 0, sizeof(rx_status));

	/*
	 * drop the packet if it has failed being decrypted by HW
	 */
	if (iwl_mvm_set_mac80211_rx_flag(mvm, hdr, &rx_status, rx_pkt_status)) {
		IWL_DEBUG_DROP(mvm, "Bad decryption results 0x%08x\n",
			       rx_pkt_status);
		return 0;
	}

	if ((unlikely(phy_info->cfg_phy_cnt > 20))) {
		IWL_DEBUG_DROP(mvm, "dsp size out of range [0,20]: %d\n",
			       phy_info->cfg_phy_cnt);
		return 0;
	}

	if (!(rx_pkt_status & RX_MPDU_RES_STATUS_CRC_OK) ||
	    !(rx_pkt_status & RX_MPDU_RES_STATUS_OVERRUN_OK)) {
		IWL_DEBUG_RX(mvm, "Bad CRC or FIFO: 0x%08X.\n", rx_pkt_status);
		return 0;
	}

	/* This will be used in several places later */
	rate_n_flags = le32_to_cpu(phy_info->rate_n_flags);

	/* rx_status carries information about the packet to mac80211 */
	rx_status.mactime = le64_to_cpu(phy_info->timestamp);
	rx_status.band =
		(phy_info->phy_flags & cpu_to_le16(RX_RES_PHY_FLAGS_BAND_24)) ?
				IEEE80211_BAND_2GHZ : IEEE80211_BAND_5GHZ;
	rx_status.freq =
		ieee80211_channel_to_frequency(le16_to_cpu(phy_info->channel),
					       rx_status.band);
	/*
	 * TSF as indicated by the fw is at INA time, but mac80211 expects the
	 * TSF at the beginning of the MPDU.
	 */
	/*rx_status.flag |= RX_FLAG_MACTIME_MPDU;*/

	/* Find max signal strength (dBm) among 3 antenna/receiver chains */
	rx_status.signal = iwl_mvm_calc_rssi(mvm, phy_info);

	IWL_DEBUG_STATS_LIMIT(mvm, "Rssi %d, TSF %llu\n", rx_status.signal,
			      (unsigned long long)rx_status.mactime);

	/*
	 * "antenna number"
	 *
	 * It seems that the antenna field in the phy flags value
	 * is actually a bit field. This is undefined by radiotap,
	 * it wants an actual antenna number but I always get "7"
	 * for most legacy frames I receive indicating that the
	 * same frame was received on all three RX chains.
	 *
	 * I think this field should be removed in favor of a
	 * new 802.11n radiotap field "RX chains" that is defined
	 * as a bitmask.
	 */
	rx_status.antenna = (le16_to_cpu(phy_info->phy_flags) &
				RX_RES_PHY_FLAGS_ANTENNA)
				>> RX_RES_PHY_FLAGS_ANTENNA_POS;

	/* set the preamble flag if appropriate */
	if (phy_info->phy_flags & cpu_to_le16(RX_RES_PHY_FLAGS_SHORT_PREAMBLE))
		rx_status.flag |= RX_FLAG_SHORTPRE;

	if (phy_info->phy_flags & cpu_to_le16(RX_RES_PHY_FLAGS_AGG)) {
		/*
		 * We know which subframes of an A-MPDU belong
		 * together since we get a single PHY response
		 * from the firmware for all of them
		 */
		rx_status.flag |= RX_FLAG_AMPDU_DETAILS;
		rx_status.ampdu_reference = mvm->ampdu_ref;
	}

	/* Set up the HT phy flags */
	switch (rate_n_flags & RATE_MCS_CHAN_WIDTH_MSK) {
	case RATE_MCS_CHAN_WIDTH_20:
		break;
	case RATE_MCS_CHAN_WIDTH_40:
		rx_status.flag |= RX_FLAG_40MHZ;
		break;
	case RATE_MCS_CHAN_WIDTH_80:
		rx_status.flag |= RX_FLAG_80MHZ;
		break;
	case RATE_MCS_CHAN_WIDTH_160:
		rx_status.flag |= RX_FLAG_160MHZ;
		break;
	}
	if (rate_n_flags & RATE_MCS_SGI_MSK)
		rx_status.flag |= RX_FLAG_SHORT_GI;
	if (rate_n_flags & RATE_HT_MCS_GF_MSK)
		rx_status.flag |= RX_FLAG_HT_GF;
	if (rate_n_flags & RATE_MCS_HT_MSK) {
		rx_status.flag |= RX_FLAG_HT;
		rx_status.rate_idx = rate_n_flags & RATE_HT_MCS_INDEX_MSK;
	} else if (rate_n_flags & RATE_MCS_VHT_MSK) {
		rx_status.vht_nss =
			((rate_n_flags & RATE_VHT_MCS_NSS_MSK) >>
						RATE_VHT_MCS_NSS_POS) + 1;
		rx_status.rate_idx = rate_n_flags & RATE_VHT_MCS_RATE_CODE_MSK;
		rx_status.flag |= RX_FLAG_VHT;
	} else {
		rx_status.rate_idx =
			iwl_mvm_legacy_rate_to_mac80211_idx(rate_n_flags,
							    rx_status.band);
	}

	iwl_mvm_pass_packet_to_mac80211(mvm, hdr, len, ampdu_status,
					rxb, &rx_status);
	return 0;
}