iwlwifi: avoid too frequent recover from statistics

[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / drivers / net / wireless / iwlwifi / iwl-rx.c

/******************************************************************************
 *
 * Copyright(c) 2003 - 2010 Intel Corporation. All rights reserved.
 *
 * Portions of this file are derived from the ipw3945 project, as well
 * as portions of the ieee80211 subsystem header files.
 *
 * 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.
 *
 * Contact Information:
 *  Intel Linux Wireless <ilw@linux.intel.com>
 * Intel Corporation, 5200 N.E. Elam Young Parkway, Hillsboro, OR 97124-6497
 *
 *****************************************************************************/

#include <linux/etherdevice.h>
#include <linux/slab.h>
#include <net/mac80211.h>
#include <asm/unaligned.h>
#include "iwl-eeprom.h"
#include "iwl-dev.h"
#include "iwl-core.h"
#include "iwl-sta.h"
#include "iwl-io.h"
#include "iwl-helpers.h"
#include "iwl-agn-calib.h"
#include "iwl-agn.h"

/******************************************************************************
 *
 * RX path functions
 *
 ******************************************************************************/

/*
 * Rx theory of operation
 *
 * Driver allocates a circular buffer of Receive Buffer Descriptors (RBDs),
 * each of which point to Receive Buffers to be filled by the NIC.  These get
 * used not only for Rx frames, but for any command response or notification
 * from the NIC.  The driver and NIC manage the Rx buffers by means
 * of indexes into the circular buffer.
 *
 * Rx Queue Indexes
 * The host/firmware share two index registers for managing the Rx buffers.
 *
 * The READ index maps to the first position that the firmware may be writing
 * to -- the driver can read up to (but not including) this position and get
 * good data.
 * The READ index is managed by the firmware once the card is enabled.
 *
 * The WRITE index maps to the last position the driver has read from -- the
 * position preceding WRITE is the last slot the firmware can place a packet.
 *
 * The queue is empty (no good data) if WRITE = READ - 1, and is full if
 * WRITE = READ.
 *
 * During initialization, the host sets up the READ queue position to the first
 * INDEX position, and WRITE to the last (READ - 1 wrapped)
 *
 * When the firmware places a packet in a buffer, it will advance the READ index
 * and fire the RX interrupt.  The driver can then query the READ index and
 * process as many packets as possible, moving the WRITE index forward as it
 * resets the Rx queue buffers with new memory.
 *
 * The management in the driver is as follows:
 * + A list of pre-allocated SKBs is stored in iwl->rxq->rx_free.  When
 *   iwl->rxq->free_count drops to or below RX_LOW_WATERMARK, work is scheduled
 *   to replenish the iwl->rxq->rx_free.
 * + In iwl_rx_replenish (scheduled) if 'processed' != 'read' then the
 *   iwl->rxq is replenished and the READ INDEX is updated (updating the
 *   'processed' and 'read' driver indexes as well)
 * + A received packet is processed and handed to the kernel network stack,
 *   detached from the iwl->rxq.  The driver 'processed' index is updated.
 * + The Host/Firmware iwl->rxq is replenished at tasklet time from the rx_free
 *   list. If there are no allocated buffers in iwl->rxq->rx_free, the READ
 *   INDEX is not incremented and iwl->status(RX_STALLED) is set.  If there
 *   were enough free buffers and RX_STALLED is set it is cleared.
 *
 *
 * Driver sequence:
 *
 * iwl_rx_queue_alloc()   Allocates rx_free
 * iwl_rx_replenish()     Replenishes rx_free list from rx_used, and calls
 *                            iwl_rx_queue_restock
 * iwl_rx_queue_restock() Moves available buffers from rx_free into Rx
 *                            queue, updates firmware pointers, and updates
 *                            the WRITE index.  If insufficient rx_free buffers
 *                            are available, schedules iwl_rx_replenish
 *
 * -- enable interrupts --
 * ISR - iwl_rx()         Detach iwl_rx_mem_buffers from pool up to the
 *                            READ INDEX, detaching the SKB from the pool.
 *                            Moves the packet buffer from queue to rx_used.
 *                            Calls iwl_rx_queue_restock to refill any empty
 *                            slots.
 * ...
 *
 */

/**
 * iwl_rx_queue_space - Return number of free slots available in queue.
 */
int iwl_rx_queue_space(const struct iwl_rx_queue *q)
{
        int s = q->read - q->write;
        if (s <= 0)
                s += RX_QUEUE_SIZE;
        /* keep some buffer to not confuse full and empty queue */
        s -= 2;
        if (s < 0)
                s = 0;
        return s;
}

/**
 * iwl_rx_queue_update_write_ptr - Update the write pointer for the RX queue
 */
void iwl_rx_queue_update_write_ptr(struct iwl_priv *priv, struct iwl_rx_queue *q)
{
        unsigned long flags;
        u32 rx_wrt_ptr_reg = priv->hw_params.rx_wrt_ptr_reg;
        u32 reg;

        spin_lock_irqsave(&q->lock, flags);

        if (q->need_update == 0)
                goto exit_unlock;

        if (priv->cfg->base_params->shadow_reg_enable) {
                /* shadow register enabled */
                /* Device expects a multiple of 8 */
                q->write_actual = (q->write & ~0x7);
                iwl_write32(priv, rx_wrt_ptr_reg, q->write_actual);
        } else {
                /* If power-saving is in use, make sure device is awake */
                if (test_bit(STATUS_POWER_PMI, &priv->status)) {
                        reg = iwl_read32(priv, CSR_UCODE_DRV_GP1);

                        if (reg & CSR_UCODE_DRV_GP1_BIT_MAC_SLEEP) {
                                IWL_DEBUG_INFO(priv,
                                        "Rx queue requesting wakeup,"
                                        " GP1 = 0x%x\n", reg);
                                iwl_set_bit(priv, CSR_GP_CNTRL,
                                        CSR_GP_CNTRL_REG_FLAG_MAC_ACCESS_REQ);
                                goto exit_unlock;
                        }

                        q->write_actual = (q->write & ~0x7);
                        iwl_write_direct32(priv, rx_wrt_ptr_reg,
                                        q->write_actual);

                /* Else device is assumed to be awake */
                } else {
                        /* Device expects a multiple of 8 */
                        q->write_actual = (q->write & ~0x7);
                        iwl_write_direct32(priv, rx_wrt_ptr_reg,
                                q->write_actual);
                }
        }
        q->need_update = 0;

 exit_unlock:
        spin_unlock_irqrestore(&q->lock, flags);
}

int iwl_rx_queue_alloc(struct iwl_priv *priv)
{
        struct iwl_rx_queue *rxq = &priv->rxq;
        struct device *dev = &priv->pci_dev->dev;
        int i;

        spin_lock_init(&rxq->lock);
        INIT_LIST_HEAD(&rxq->rx_free);
        INIT_LIST_HEAD(&rxq->rx_used);

        /* Alloc the circular buffer of Read Buffer Descriptors (RBDs) */
        rxq->bd = dma_alloc_coherent(dev, 4 * RX_QUEUE_SIZE, &rxq->bd_dma,
                                     GFP_KERNEL);
        if (!rxq->bd)
                goto err_bd;

        rxq->rb_stts = dma_alloc_coherent(dev, sizeof(struct iwl_rb_status),
                                          &rxq->rb_stts_dma, GFP_KERNEL);
        if (!rxq->rb_stts)
                goto err_rb;

        /* Fill the rx_used queue with _all_ of the Rx buffers */
        for (i = 0; i < RX_FREE_BUFFERS + RX_QUEUE_SIZE; i++)
                list_add_tail(&rxq->pool[i].list, &rxq->rx_used);

        /* Set us so that we have processed and used all buffers, but have
         * not restocked the Rx queue with fresh buffers */
        rxq->read = rxq->write = 0;
        rxq->write_actual = 0;
        rxq->free_count = 0;
        rxq->need_update = 0;
        return 0;

err_rb:
        dma_free_coherent(&priv->pci_dev->dev, 4 * RX_QUEUE_SIZE, rxq->bd,
                          rxq->bd_dma);
err_bd:
        return -ENOMEM;
}

/******************************************************************************
 *
 * Generic RX handler implementations
 *
 ******************************************************************************/

static void iwl_rx_reply_alive(struct iwl_priv *priv,
                               struct iwl_rx_mem_buffer *rxb)
{
        struct iwl_rx_packet *pkt = rxb_addr(rxb);
        struct iwl_alive_resp *palive;
        struct delayed_work *pwork;

        palive = &pkt->u.alive_frame;

        IWL_DEBUG_INFO(priv, "Alive ucode status 0x%08X revision "
                       "0x%01X 0x%01X\n",
                       palive->is_valid, palive->ver_type,
                       palive->ver_subtype);

        if (palive->ver_subtype == INITIALIZE_SUBTYPE) {
                IWL_DEBUG_INFO(priv, "Initialization Alive received.\n");
                memcpy(&priv->card_alive_init,
                       &pkt->u.alive_frame,
                       sizeof(struct iwl_init_alive_resp));
                pwork = &priv->init_alive_start;
        } else {
                IWL_DEBUG_INFO(priv, "Runtime Alive received.\n");
                memcpy(&priv->card_alive, &pkt->u.alive_frame,
                       sizeof(struct iwl_alive_resp));
                pwork = &priv->alive_start;
        }

        /* We delay the ALIVE response by 5ms to
         * give the HW RF Kill time to activate... */
        if (palive->is_valid == UCODE_VALID_OK)
                queue_delayed_work(priv->workqueue, pwork,
                                   msecs_to_jiffies(5));
        else {
                IWL_WARN(priv, "%s uCode did not respond OK.\n",
                        (palive->ver_subtype == INITIALIZE_SUBTYPE) ?
                        "init" : "runtime");
                /*
                 * If fail to load init uCode,
                 * let's try to load the init uCode again.
                 * We should not get into this situation, but if it
                 * does happen, we should not move on and loading "runtime"
                 * without proper calibrate the device.
                 */
                if (palive->ver_subtype == INITIALIZE_SUBTYPE)
                        priv->ucode_type = UCODE_NONE;
                queue_work(priv->workqueue, &priv->restart);
        }
}

static void iwl_rx_reply_error(struct iwl_priv *priv,
                               struct iwl_rx_mem_buffer *rxb)
{
        struct iwl_rx_packet *pkt = rxb_addr(rxb);

        IWL_ERR(priv, "Error Reply type 0x%08X cmd %s (0x%02X) "
                "seq 0x%04X ser 0x%08X\n",
                le32_to_cpu(pkt->u.err_resp.error_type),
                get_cmd_string(pkt->u.err_resp.cmd_id),
                pkt->u.err_resp.cmd_id,
                le16_to_cpu(pkt->u.err_resp.bad_cmd_seq_num),
                le32_to_cpu(pkt->u.err_resp.error_info));
}

static void iwl_rx_csa(struct iwl_priv *priv, struct iwl_rx_mem_buffer *rxb)
{
        struct iwl_rx_packet *pkt = rxb_addr(rxb);
        struct iwl_csa_notification *csa = &(pkt->u.csa_notif);
        /*
         * MULTI-FIXME
         * See iwl_mac_channel_switch.
         */
        struct iwl_rxon_context *ctx = &priv->contexts[IWL_RXON_CTX_BSS];
        struct iwl_rxon_cmd *rxon = (void *)&ctx->active;

        if (priv->switch_rxon.switch_in_progress) {
                if (!le32_to_cpu(csa->status) &&
                    (csa->channel == priv->switch_rxon.channel)) {
                        rxon->channel = csa->channel;
                        ctx->staging.channel = csa->channel;
                        IWL_DEBUG_11H(priv, "CSA notif: channel %d\n",
                              le16_to_cpu(csa->channel));
                        iwl_chswitch_done(priv, true);
                } else {
                        IWL_ERR(priv, "CSA notif (fail) : channel %d\n",
                              le16_to_cpu(csa->channel));
                        iwl_chswitch_done(priv, false);
                }
        }
}


static void iwl_rx_spectrum_measure_notif(struct iwl_priv *priv,
                                          struct iwl_rx_mem_buffer *rxb)
{
        struct iwl_rx_packet *pkt = rxb_addr(rxb);
        struct iwl_spectrum_notification *report = &(pkt->u.spectrum_notif);

        if (!report->state) {
                IWL_DEBUG_11H(priv,
                        "Spectrum Measure Notification: Start\n");
                return;
        }

        memcpy(&priv->measure_report, report, sizeof(*report));
        priv->measurement_status |= MEASUREMENT_READY;
}

static void iwl_rx_pm_sleep_notif(struct iwl_priv *priv,
                                  struct iwl_rx_mem_buffer *rxb)
{
#ifdef CONFIG_IWLWIFI_DEBUG
        struct iwl_rx_packet *pkt = rxb_addr(rxb);
        struct iwl_sleep_notification *sleep = &(pkt->u.sleep_notif);
        IWL_DEBUG_RX(priv, "sleep mode: %d, src: %d\n",
                     sleep->pm_sleep_mode, sleep->pm_wakeup_src);
#endif
}

static void iwl_rx_pm_debug_statistics_notif(struct iwl_priv *priv,
                                             struct iwl_rx_mem_buffer *rxb)
{
        struct iwl_rx_packet *pkt = rxb_addr(rxb);
        u32 len = le32_to_cpu(pkt->len_n_flags) & FH_RSCSR_FRAME_SIZE_MSK;
        IWL_DEBUG_RADIO(priv, "Dumping %d bytes of unhandled "
                        "notification for %s:\n", len,
                        get_cmd_string(pkt->hdr.cmd));
        iwl_print_hex_dump(priv, IWL_DL_RADIO, pkt->u.raw, len);
}

static void iwl_rx_beacon_notif(struct iwl_priv *priv,
                                struct iwl_rx_mem_buffer *rxb)
{
        struct iwl_rx_packet *pkt = rxb_addr(rxb);
        struct iwlagn_beacon_notif *beacon = (void *)pkt->u.raw;
#ifdef CONFIG_IWLWIFI_DEBUG
        u16 status = le16_to_cpu(beacon->beacon_notify_hdr.status.status);
        u8 rate = iwl_hw_get_rate(beacon->beacon_notify_hdr.rate_n_flags);

        IWL_DEBUG_RX(priv, "beacon status %#x, retries:%d ibssmgr:%d "
                "tsf:0x%.8x%.8x rate:%d\n",
                status & TX_STATUS_MSK,
                beacon->beacon_notify_hdr.failure_frame,
                le32_to_cpu(beacon->ibss_mgr_status),
                le32_to_cpu(beacon->high_tsf),
                le32_to_cpu(beacon->low_tsf), rate);
#endif

        priv->ibss_manager = le32_to_cpu(beacon->ibss_mgr_status);

        if (!test_bit(STATUS_EXIT_PENDING, &priv->status))
                queue_work(priv->workqueue, &priv->beacon_update);
}

/* the threshold ratio of actual_ack_cnt to expected_ack_cnt in percent */
#define ACK_CNT_RATIO (50)
#define BA_TIMEOUT_CNT (5)
#define BA_TIMEOUT_MAX (16)

/**
 * iwl_good_ack_health - checks for ACK count ratios, BA timeout retries.
 *
 * When the ACK count ratio is low and aggregated BA timeout retries exceeding
 * the BA_TIMEOUT_MAX, reload firmware and bring system back to normal
 * operation state.
 */
static bool iwl_good_ack_health(struct iwl_priv *priv, struct iwl_rx_packet *pkt)
{
        int actual_delta, expected_delta, ba_timeout_delta;
        struct statistics_tx *cur, *old;

        if (priv->_agn.agg_tids_count)
                return true;

        if (iwl_bt_statistics(priv)) {
                cur = &pkt->u.stats_bt.tx;
                old = &priv->_agn.statistics_bt.tx;
        } else {
                cur = &pkt->u.stats.tx;
                old = &priv->_agn.statistics.tx;
        }

        actual_delta = le32_to_cpu(cur->actual_ack_cnt) -
                       le32_to_cpu(old->actual_ack_cnt);
        expected_delta = le32_to_cpu(cur->expected_ack_cnt) -
                         le32_to_cpu(old->expected_ack_cnt);

        /* Values should not be negative, but we do not trust the firmware */
        if (actual_delta <= 0 || expected_delta <= 0)
                return true;

        ba_timeout_delta = le32_to_cpu(cur->agg.ba_timeout) -
                           le32_to_cpu(old->agg.ba_timeout);

        if ((actual_delta * 100 / expected_delta) < ACK_CNT_RATIO &&
            ba_timeout_delta > BA_TIMEOUT_CNT) {
                IWL_DEBUG_RADIO(priv, "deltas: actual %d expected %d ba_timeout %d\n",
                                actual_delta, expected_delta, ba_timeout_delta);

#ifdef CONFIG_IWLWIFI_DEBUGFS
                /*
                 * This is ifdef'ed on DEBUGFS because otherwise the
                 * statistics aren't available. If DEBUGFS is set but
                 * DEBUG is not, these will just compile out.
                 */
                IWL_DEBUG_RADIO(priv, "rx_detected_cnt delta %d\n",
                                priv->_agn.delta_statistics.tx.rx_detected_cnt);
                IWL_DEBUG_RADIO(priv,
                                "ack_or_ba_timeout_collision delta %d\n",
                                priv->_agn.delta_statistics.tx.ack_or_ba_timeout_collision);
#endif

                if (ba_timeout_delta >= BA_TIMEOUT_MAX)
                        return false;
        }

        return true;
}

/**
 * iwl_good_plcp_health - checks for plcp error.
 *
 * When the plcp error is exceeding the thresholds, reset the radio
 * to improve the throughput.
 */
static bool iwl_good_plcp_health(struct iwl_priv *priv,
                                 struct iwl_rx_packet *pkt, unsigned int msecs)
{
        int delta;
        int threshold = priv->cfg->base_params->plcp_delta_threshold;

        if (threshold == IWL_MAX_PLCP_ERR_THRESHOLD_DISABLE) {
                IWL_DEBUG_RADIO(priv, "plcp_err check disabled\n");
                return true;
        }

        if (iwl_bt_statistics(priv)) {
                struct statistics_rx_bt *cur, *old;

                cur = &pkt->u.stats_bt.rx;
                old = &priv->_agn.statistics_bt.rx;

                delta = le32_to_cpu(cur->ofdm.plcp_err) -
                        le32_to_cpu(old->ofdm.plcp_err) +
                        le32_to_cpu(cur->ofdm_ht.plcp_err) -
                        le32_to_cpu(old->ofdm_ht.plcp_err);
        } else {
                struct statistics_rx *cur, *old;

                cur = &pkt->u.stats.rx;
                old = &priv->_agn.statistics.rx;

                delta = le32_to_cpu(cur->ofdm.plcp_err) -
                        le32_to_cpu(old->ofdm.plcp_err) +
                        le32_to_cpu(cur->ofdm_ht.plcp_err) -
                        le32_to_cpu(old->ofdm_ht.plcp_err);
        }

        /* Can be negative if firmware reseted statistics */
        if (delta <= 0)
                return true;

        if ((delta * 100 / msecs) > threshold) {
                IWL_DEBUG_RADIO(priv,
                                "plcp health threshold %u delta %d msecs %u\n",
                                threshold, delta, msecs);
                return false;
        }

        return true;
}

static void iwl_recover_from_statistics(struct iwl_priv *priv,
                                        struct iwl_rx_packet *pkt)
{
        const struct iwl_mod_params *mod_params = priv->cfg->mod_params;
        unsigned int msecs;
        unsigned long stamp;

        if (test_bit(STATUS_EXIT_PENDING, &priv->status))
                return;

        stamp = jiffies;
        msecs = jiffies_to_msecs(stamp - priv->rx_statistics_jiffies);

        /* Only gather statistics and update time stamp when not associated */
        if (!iwl_is_any_associated(priv))
                goto out;

        /* Do not check/recover when do not have enough statistics data */
        if (msecs < 99)
                return;

        if (mod_params->ack_check && !iwl_good_ack_health(priv, pkt)) {
                IWL_ERR(priv, "low ack count detected, restart firmware\n");
                if (!iwl_force_reset(priv, IWL_FW_RESET, false))
                        return;
        }

        if (mod_params->plcp_check && !iwl_good_plcp_health(priv, pkt, msecs))
                iwl_force_reset(priv, IWL_RF_RESET, false);

out:
        if (iwl_bt_statistics(priv))
                memcpy(&priv->_agn.statistics_bt, &pkt->u.stats_bt,
                        sizeof(priv->_agn.statistics_bt));
        else
                memcpy(&priv->_agn.statistics, &pkt->u.stats,
                        sizeof(priv->_agn.statistics));

        priv->rx_statistics_jiffies = stamp;
}

/* Calculate noise level, based on measurements during network silence just
 *   before arriving beacon.  This measurement can be done only if we know
 *   exactly when to expect beacons, therefore only when we're associated. */
static void iwl_rx_calc_noise(struct iwl_priv *priv)
{
        struct statistics_rx_non_phy *rx_info;
        int num_active_rx = 0;
        int total_silence = 0;
        int bcn_silence_a, bcn_silence_b, bcn_silence_c;
        int last_rx_noise;

        if (iwl_bt_statistics(priv))
                rx_info = &(priv->_agn.statistics_bt.rx.general.common);
        else
                rx_info = &(priv->_agn.statistics.rx.general);
        bcn_silence_a =
                le32_to_cpu(rx_info->beacon_silence_rssi_a) & IN_BAND_FILTER;
        bcn_silence_b =
                le32_to_cpu(rx_info->beacon_silence_rssi_b) & IN_BAND_FILTER;
        bcn_silence_c =
                le32_to_cpu(rx_info->beacon_silence_rssi_c) & IN_BAND_FILTER;

        if (bcn_silence_a) {
                total_silence += bcn_silence_a;
                num_active_rx++;
        }
        if (bcn_silence_b) {
                total_silence += bcn_silence_b;
                num_active_rx++;
        }
        if (bcn_silence_c) {
                total_silence += bcn_silence_c;
                num_active_rx++;
        }

        /* Average among active antennas */
        if (num_active_rx)
                last_rx_noise = (total_silence / num_active_rx) - 107;
        else
                last_rx_noise = IWL_NOISE_MEAS_NOT_AVAILABLE;

        IWL_DEBUG_CALIB(priv, "inband silence a %u, b %u, c %u, dBm %d\n",
                        bcn_silence_a, bcn_silence_b, bcn_silence_c,
                        last_rx_noise);
}

/*
 *  based on the assumption of all statistics counter are in DWORD
 *  FIXME: This function is for debugging, do not deal with
 *  the case of counters roll-over.
 */
static void iwl_accumulative_statistics(struct iwl_priv *priv,
                                        __le32 *stats)
{
#ifdef CONFIG_IWLWIFI_DEBUGFS
        int i, size;
        __le32 *prev_stats;
        u32 *accum_stats;
        u32 *delta, *max_delta;
        struct statistics_general_common *general, *accum_general;
        struct statistics_tx *tx, *accum_tx;

        if (iwl_bt_statistics(priv)) {
                prev_stats = (__le32 *)&priv->_agn.statistics_bt;
                accum_stats = (u32 *)&priv->_agn.accum_statistics_bt;
                size = sizeof(struct iwl_bt_notif_statistics);
                general = &priv->_agn.statistics_bt.general.common;
                accum_general = &priv->_agn.accum_statistics_bt.general.common;
                tx = &priv->_agn.statistics_bt.tx;
                accum_tx = &priv->_agn.accum_statistics_bt.tx;
                delta = (u32 *)&priv->_agn.delta_statistics_bt;
                max_delta = (u32 *)&priv->_agn.max_delta_bt;
        } else {
                prev_stats = (__le32 *)&priv->_agn.statistics;
                accum_stats = (u32 *)&priv->_agn.accum_statistics;
                size = sizeof(struct iwl_notif_statistics);
                general = &priv->_agn.statistics.general.common;
                accum_general = &priv->_agn.accum_statistics.general.common;
                tx = &priv->_agn.statistics.tx;
                accum_tx = &priv->_agn.accum_statistics.tx;
                delta = (u32 *)&priv->_agn.delta_statistics;
                max_delta = (u32 *)&priv->_agn.max_delta;
        }
        for (i = sizeof(__le32); i < size;
             i += sizeof(__le32), stats++, prev_stats++, delta++,
             max_delta++, accum_stats++) {
                if (le32_to_cpu(*stats) > le32_to_cpu(*prev_stats)) {
                        *delta = (le32_to_cpu(*stats) -
                                le32_to_cpu(*prev_stats));
                        *accum_stats += *delta;
                        if (*delta > *max_delta)
                                *max_delta = *delta;
                }
        }

        /* reset accumulative statistics for "no-counter" type statistics */
        accum_general->temperature = general->temperature;
        accum_general->temperature_m = general->temperature_m;
        accum_general->ttl_timestamp = general->ttl_timestamp;
        accum_tx->tx_power.ant_a = tx->tx_power.ant_a;
        accum_tx->tx_power.ant_b = tx->tx_power.ant_b;
        accum_tx->tx_power.ant_c = tx->tx_power.ant_c;
#endif
}

static void iwl_rx_statistics(struct iwl_priv *priv,
                              struct iwl_rx_mem_buffer *rxb)
{
        const int reg_recalib_period = 60;
        int change;
        struct iwl_rx_packet *pkt = rxb_addr(rxb);

        if (iwl_bt_statistics(priv)) {
                IWL_DEBUG_RX(priv,
                             "Statistics notification received (%d vs %d).\n",
                             (int)sizeof(struct iwl_bt_notif_statistics),
                             le32_to_cpu(pkt->len_n_flags) &
                             FH_RSCSR_FRAME_SIZE_MSK);

                change = ((priv->_agn.statistics_bt.general.common.temperature !=
                           pkt->u.stats_bt.general.common.temperature) ||
                           ((priv->_agn.statistics_bt.flag &
                           STATISTICS_REPLY_FLG_HT40_MODE_MSK) !=
                           (pkt->u.stats_bt.flag &
                           STATISTICS_REPLY_FLG_HT40_MODE_MSK)));

                iwl_accumulative_statistics(priv, (__le32 *)&pkt->u.stats_bt);
        } else {
                IWL_DEBUG_RX(priv,
                             "Statistics notification received (%d vs %d).\n",
                             (int)sizeof(struct iwl_notif_statistics),
                             le32_to_cpu(pkt->len_n_flags) &
                             FH_RSCSR_FRAME_SIZE_MSK);

                change = ((priv->_agn.statistics.general.common.temperature !=
                           pkt->u.stats.general.common.temperature) ||
                           ((priv->_agn.statistics.flag &
                           STATISTICS_REPLY_FLG_HT40_MODE_MSK) !=
                           (pkt->u.stats.flag &
                           STATISTICS_REPLY_FLG_HT40_MODE_MSK)));

                iwl_accumulative_statistics(priv, (__le32 *)&pkt->u.stats);
        }

        iwl_recover_from_statistics(priv, pkt);

        set_bit(STATUS_STATISTICS, &priv->status);

        /* Reschedule the statistics timer to occur in
         * reg_recalib_period seconds to ensure we get a
         * thermal update even if the uCode doesn't give
         * us one */
        mod_timer(&priv->statistics_periodic, jiffies +
                  msecs_to_jiffies(reg_recalib_period * 1000));

        if (unlikely(!test_bit(STATUS_SCANNING, &priv->status)) &&
            (pkt->hdr.cmd == STATISTICS_NOTIFICATION)) {
                iwl_rx_calc_noise(priv);
                queue_work(priv->workqueue, &priv->run_time_calib_work);
        }
        if (priv->cfg->ops->lib->temp_ops.temperature && change)
                priv->cfg->ops->lib->temp_ops.temperature(priv);
}

static void iwl_rx_reply_statistics(struct iwl_priv *priv,
                                    struct iwl_rx_mem_buffer *rxb)
{
        struct iwl_rx_packet *pkt = rxb_addr(rxb);

        if (le32_to_cpu(pkt->u.stats.flag) & UCODE_STATISTICS_CLEAR_MSK) {
#ifdef CONFIG_IWLWIFI_DEBUGFS
                memset(&priv->_agn.accum_statistics, 0,
                        sizeof(struct iwl_notif_statistics));
                memset(&priv->_agn.delta_statistics, 0,
                        sizeof(struct iwl_notif_statistics));
                memset(&priv->_agn.max_delta, 0,
                        sizeof(struct iwl_notif_statistics));
                memset(&priv->_agn.accum_statistics_bt, 0,
                        sizeof(struct iwl_bt_notif_statistics));
                memset(&priv->_agn.delta_statistics_bt, 0,
                        sizeof(struct iwl_bt_notif_statistics));
                memset(&priv->_agn.max_delta_bt, 0,
                        sizeof(struct iwl_bt_notif_statistics));
#endif
                IWL_DEBUG_RX(priv, "Statistics have been cleared\n");
        }
        iwl_rx_statistics(priv, rxb);
}

/* Handle notification from uCode that card's power state is changing
 * due to software, hardware, or critical temperature RFKILL */
static void iwl_rx_card_state_notif(struct iwl_priv *priv,
                                    struct iwl_rx_mem_buffer *rxb)
{
        struct iwl_rx_packet *pkt = rxb_addr(rxb);
        u32 flags = le32_to_cpu(pkt->u.card_state_notif.flags);
        unsigned long status = priv->status;

        IWL_DEBUG_RF_KILL(priv, "Card state received: HW:%s SW:%s CT:%s\n",
                          (flags & HW_CARD_DISABLED) ? "Kill" : "On",
                          (flags & SW_CARD_DISABLED) ? "Kill" : "On",
                          (flags & CT_CARD_DISABLED) ?
                          "Reached" : "Not reached");

        if (flags & (SW_CARD_DISABLED | HW_CARD_DISABLED |
                     CT_CARD_DISABLED)) {

                iwl_write32(priv, CSR_UCODE_DRV_GP1_SET,
                            CSR_UCODE_DRV_GP1_BIT_CMD_BLOCKED);

                iwl_write_direct32(priv, HBUS_TARG_MBX_C,
                                        HBUS_TARG_MBX_C_REG_BIT_CMD_BLOCKED);

                if (!(flags & RXON_CARD_DISABLED)) {
                        iwl_write32(priv, CSR_UCODE_DRV_GP1_CLR,
                                    CSR_UCODE_DRV_GP1_BIT_CMD_BLOCKED);
                        iwl_write_direct32(priv, HBUS_TARG_MBX_C,
                                        HBUS_TARG_MBX_C_REG_BIT_CMD_BLOCKED);
                }
                if (flags & CT_CARD_DISABLED)
                        iwl_tt_enter_ct_kill(priv);
        }
        if (!(flags & CT_CARD_DISABLED))
                iwl_tt_exit_ct_kill(priv);

        if (flags & HW_CARD_DISABLED)
                set_bit(STATUS_RF_KILL_HW, &priv->status);
        else
                clear_bit(STATUS_RF_KILL_HW, &priv->status);


        if (!(flags & RXON_CARD_DISABLED))
                iwl_scan_cancel(priv);

        if ((test_bit(STATUS_RF_KILL_HW, &status) !=
             test_bit(STATUS_RF_KILL_HW, &priv->status)))
                wiphy_rfkill_set_hw_state(priv->hw->wiphy,
                        test_bit(STATUS_RF_KILL_HW, &priv->status));
        else
                wake_up_interruptible(&priv->wait_command_queue);
}

static void iwl_rx_missed_beacon_notif(struct iwl_priv *priv,
                                       struct iwl_rx_mem_buffer *rxb)

{
        struct iwl_rx_packet *pkt = rxb_addr(rxb);
        struct iwl_missed_beacon_notif *missed_beacon;

        missed_beacon = &pkt->u.missed_beacon;
        if (le32_to_cpu(missed_beacon->consecutive_missed_beacons) >
            priv->missed_beacon_threshold) {
                IWL_DEBUG_CALIB(priv,
                    "missed bcn cnsq %d totl %d rcd %d expctd %d\n",
                    le32_to_cpu(missed_beacon->consecutive_missed_beacons),
                    le32_to_cpu(missed_beacon->total_missed_becons),
                    le32_to_cpu(missed_beacon->num_recvd_beacons),
                    le32_to_cpu(missed_beacon->num_expected_beacons));
                if (!test_bit(STATUS_SCANNING, &priv->status))
                        iwl_init_sensitivity(priv);
        }
}

/* Cache phy data (Rx signal strength, etc) for HT frame (REPLY_RX_PHY_CMD).
 * This will be used later in iwl_rx_reply_rx() for REPLY_RX_MPDU_CMD. */
static void iwl_rx_reply_rx_phy(struct iwl_priv *priv,
                                struct iwl_rx_mem_buffer *rxb)
{
        struct iwl_rx_packet *pkt = rxb_addr(rxb);

        priv->_agn.last_phy_res_valid = true;
        memcpy(&priv->_agn.last_phy_res, pkt->u.raw,
               sizeof(struct iwl_rx_phy_res));
}

/*
 * returns non-zero if packet should be dropped
 */
static int iwl_set_decrypted_flag(struct iwl_priv *priv,
                                  struct ieee80211_hdr *hdr,
                                  u32 decrypt_res,
                                  struct ieee80211_rx_status *stats)
{
        u16 fc = le16_to_cpu(hdr->frame_control);

        /*
         * All contexts have the same setting here due to it being
         * a module parameter, so OK to check any context.
         */
        if (priv->contexts[IWL_RXON_CTX_BSS].active.filter_flags &
                                                RXON_FILTER_DIS_DECRYPT_MSK)
                return 0;

        if (!(fc & IEEE80211_FCTL_PROTECTED))
                return 0;

        IWL_DEBUG_RX(priv, "decrypt_res:0x%x\n", decrypt_res);
        switch (decrypt_res & RX_RES_STATUS_SEC_TYPE_MSK) {
        case RX_RES_STATUS_SEC_TYPE_TKIP:
                /* The uCode has got a bad phase 1 Key, pushes the packet.
                 * Decryption will be done in SW. */
                if ((decrypt_res & RX_RES_STATUS_DECRYPT_TYPE_MSK) ==
                    RX_RES_STATUS_BAD_KEY_TTAK)
                        break;

        case RX_RES_STATUS_SEC_TYPE_WEP:
                if ((decrypt_res & RX_RES_STATUS_DECRYPT_TYPE_MSK) ==
                    RX_RES_STATUS_BAD_ICV_MIC) {
                        /* bad ICV, the packet is destroyed since the
                         * decryption is inplace, drop it */
                        IWL_DEBUG_RX(priv, "Packet destroyed\n");
                        return -1;
                }
        case RX_RES_STATUS_SEC_TYPE_CCMP:
                if ((decrypt_res & RX_RES_STATUS_DECRYPT_TYPE_MSK) ==
                    RX_RES_STATUS_DECRYPT_OK) {
                        IWL_DEBUG_RX(priv, "hw decrypt successfully!!!\n");
                        stats->flag |= RX_FLAG_DECRYPTED;
                }
                break;

        default:
                break;
        }
        return 0;
}

static void iwl_pass_packet_to_mac80211(struct iwl_priv *priv,
                                        struct ieee80211_hdr *hdr,
                                        u16 len,
                                        u32 ampdu_status,
                                        struct iwl_rx_mem_buffer *rxb,
                                        struct ieee80211_rx_status *stats)
{
        struct sk_buff *skb;
        __le16 fc = hdr->frame_control;

        /* We only process data packets if the interface is open */
        if (unlikely(!priv->is_open)) {
                IWL_DEBUG_DROP_LIMIT(priv,
                    "Dropping packet while interface is not open.\n");
                return;
        }

        /* In case of HW accelerated crypto and bad decryption, drop */
        if (!priv->cfg->mod_params->sw_crypto &&
            iwl_set_decrypted_flag(priv, hdr, ampdu_status, stats))
                return;

        skb = dev_alloc_skb(128);
        if (!skb) {
                IWL_ERR(priv, "dev_alloc_skb failed\n");
                return;
        }

        skb_add_rx_frag(skb, 0, rxb->page, (void *)hdr - rxb_addr(rxb), len);

        iwl_update_stats(priv, false, fc, len);
        memcpy(IEEE80211_SKB_RXCB(skb), stats, sizeof(*stats));

        ieee80211_rx(priv->hw, skb);
        priv->alloc_rxb_page--;
        rxb->page = NULL;
}

static u32 iwl_translate_rx_status(struct iwl_priv *priv, u32 decrypt_in)
{
        u32 decrypt_out = 0;

        if ((decrypt_in & RX_RES_STATUS_STATION_FOUND) ==
                                        RX_RES_STATUS_STATION_FOUND)
                decrypt_out |= (RX_RES_STATUS_STATION_FOUND |
                                RX_RES_STATUS_NO_STATION_INFO_MISMATCH);

        decrypt_out |= (decrypt_in & RX_RES_STATUS_SEC_TYPE_MSK);

        /* packet was not encrypted */
        if ((decrypt_in & RX_RES_STATUS_SEC_TYPE_MSK) ==
                                        RX_RES_STATUS_SEC_TYPE_NONE)
                return decrypt_out;

        /* packet was encrypted with unknown alg */
        if ((decrypt_in & RX_RES_STATUS_SEC_TYPE_MSK) ==
                                        RX_RES_STATUS_SEC_TYPE_ERR)
                return decrypt_out;

        /* decryption was not done in HW */
        if ((decrypt_in & RX_MPDU_RES_STATUS_DEC_DONE_MSK) !=
                                        RX_MPDU_RES_STATUS_DEC_DONE_MSK)
                return decrypt_out;

        switch (decrypt_in & RX_RES_STATUS_SEC_TYPE_MSK) {

        case RX_RES_STATUS_SEC_TYPE_CCMP:
                /* alg is CCM: check MIC only */
                if (!(decrypt_in & RX_MPDU_RES_STATUS_MIC_OK))
                        /* Bad MIC */
                        decrypt_out |= RX_RES_STATUS_BAD_ICV_MIC;
                else
                        decrypt_out |= RX_RES_STATUS_DECRYPT_OK;

                break;

        case RX_RES_STATUS_SEC_TYPE_TKIP:
                if (!(decrypt_in & RX_MPDU_RES_STATUS_TTAK_OK)) {
                        /* Bad TTAK */
                        decrypt_out |= RX_RES_STATUS_BAD_KEY_TTAK;
                        break;
                }
                /* fall through if TTAK OK */
        default:
                if (!(decrypt_in & RX_MPDU_RES_STATUS_ICV_OK))
                        decrypt_out |= RX_RES_STATUS_BAD_ICV_MIC;
                else
                        decrypt_out |= RX_RES_STATUS_DECRYPT_OK;
                break;
        }

        IWL_DEBUG_RX(priv, "decrypt_in:0x%x  decrypt_out = 0x%x\n",
                                        decrypt_in, decrypt_out);

        return decrypt_out;
}

/* Called for REPLY_RX (legacy ABG frames), or
 * REPLY_RX_MPDU_CMD (HT high-throughput N frames). */
static void iwl_rx_reply_rx(struct iwl_priv *priv,
                            struct iwl_rx_mem_buffer *rxb)
{
        struct ieee80211_hdr *header;
        struct ieee80211_rx_status rx_status;
        struct iwl_rx_packet *pkt = rxb_addr(rxb);
        struct iwl_rx_phy_res *phy_res;
        __le32 rx_pkt_status;
        struct iwl_rx_mpdu_res_start *amsdu;
        u32 len;
        u32 ampdu_status;
        u32 rate_n_flags;

        /**
         * REPLY_RX and REPLY_RX_MPDU_CMD are handled differently.
         *      REPLY_RX: physical layer info is in this buffer
         *      REPLY_RX_MPDU_CMD: physical layer info was sent in separate
         *              command and cached in priv->last_phy_res
         *
         * Here we set up local variables depending on which command is
         * received.
         */
        if (pkt->hdr.cmd == REPLY_RX) {
                phy_res = (struct iwl_rx_phy_res *)pkt->u.raw;
                header = (struct ieee80211_hdr *)(pkt->u.raw + sizeof(*phy_res)
                                + phy_res->cfg_phy_cnt);

                len = le16_to_cpu(phy_res->byte_count);
                rx_pkt_status = *(__le32 *)(pkt->u.raw + sizeof(*phy_res) +
                                phy_res->cfg_phy_cnt + len);
                ampdu_status = le32_to_cpu(rx_pkt_status);
        } else {
                if (!priv->_agn.last_phy_res_valid) {
                        IWL_ERR(priv, "MPDU frame without cached PHY data\n");
                        return;
                }
                phy_res = &priv->_agn.last_phy_res;
                amsdu = (struct iwl_rx_mpdu_res_start *)pkt->u.raw;
                header = (struct ieee80211_hdr *)(pkt->u.raw + sizeof(*amsdu));
                len = le16_to_cpu(amsdu->byte_count);
                rx_pkt_status = *(__le32 *)(pkt->u.raw + sizeof(*amsdu) + len);
                ampdu_status = iwl_translate_rx_status(priv,
                                                le32_to_cpu(rx_pkt_status));
        }

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

        if (!(rx_pkt_status & RX_RES_STATUS_NO_CRC32_ERROR) ||
            !(rx_pkt_status & RX_RES_STATUS_NO_RXE_OVERFLOW)) {
                IWL_DEBUG_RX(priv, "Bad CRC or FIFO: 0x%08X.\n",
                                le32_to_cpu(rx_pkt_status));
                return;
        }

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

        /* rx_status carries information about the packet to mac80211 */
        rx_status.mactime = le64_to_cpu(phy_res->timestamp);
        rx_status.band = (phy_res->phy_flags & RX_RES_PHY_FLAGS_BAND_24_MSK) ?
                                IEEE80211_BAND_2GHZ : IEEE80211_BAND_5GHZ;
        rx_status.freq =
                ieee80211_channel_to_frequency(le16_to_cpu(phy_res->channel),
                                               rx_status.band);
        rx_status.rate_idx =
                iwlagn_hwrate_to_mac80211_idx(rate_n_flags, rx_status.band);
        rx_status.flag = 0;

        /* TSF isn't reliable. In order to allow smooth user experience,
         * this W/A doesn't propagate it to the mac80211 */
        /*rx_status.flag |= RX_FLAG_MACTIME_MPDU;*/

        priv->ucode_beacon_time = le32_to_cpu(phy_res->beacon_time_stamp);

        /* Find max signal strength (dBm) among 3 antenna/receiver chains */
        rx_status.signal = priv->cfg->ops->utils->calc_rssi(priv, phy_res);

        iwl_dbg_log_rx_data_frame(priv, len, header);
        IWL_DEBUG_STATS_LIMIT(priv, "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_res->phy_flags) & RX_RES_PHY_FLAGS_ANTENNA_MSK)
                >> RX_RES_PHY_FLAGS_ANTENNA_POS;

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

        /* Set up the HT phy flags */
        if (rate_n_flags & RATE_MCS_HT_MSK)
                rx_status.flag |= RX_FLAG_HT;
        if (rate_n_flags & RATE_MCS_HT40_MSK)
                rx_status.flag |= RX_FLAG_40MHZ;
        if (rate_n_flags & RATE_MCS_SGI_MSK)
                rx_status.flag |= RX_FLAG_SHORT_GI;

        iwl_pass_packet_to_mac80211(priv, header, len, ampdu_status,
                                    rxb, &rx_status);
}

/**
 * iwl_setup_rx_handlers - Initialize Rx handler callbacks
 *
 * Setup the RX handlers for each of the reply types sent from the uCode
 * to the host.
 */
void iwl_setup_rx_handlers(struct iwl_priv *priv)
{
        void (**handlers)(struct iwl_priv *priv, struct iwl_rx_mem_buffer *rxb);

        handlers = priv->rx_handlers;

        handlers[REPLY_ALIVE]                   = iwl_rx_reply_alive;
        handlers[REPLY_ERROR]                   = iwl_rx_reply_error;
        handlers[CHANNEL_SWITCH_NOTIFICATION]   = iwl_rx_csa;
        handlers[SPECTRUM_MEASURE_NOTIFICATION] = iwl_rx_spectrum_measure_notif;
        handlers[PM_SLEEP_NOTIFICATION]         = iwl_rx_pm_sleep_notif;
        handlers[PM_DEBUG_STATISTIC_NOTIFIC]    = iwl_rx_pm_debug_statistics_notif;
        handlers[BEACON_NOTIFICATION]           = iwl_rx_beacon_notif;

        /*
         * The same handler is used for both the REPLY to a discrete
         * statistics request from the host as well as for the periodic
         * statistics notifications (after received beacons) from the uCode.
         */
        handlers[REPLY_STATISTICS_CMD]          = iwl_rx_reply_statistics;
        handlers[STATISTICS_NOTIFICATION]       = iwl_rx_statistics;

        iwl_setup_rx_scan_handlers(priv);

        handlers[CARD_STATE_NOTIFICATION]       = iwl_rx_card_state_notif;
        handlers[MISSED_BEACONS_NOTIFICATION]   = iwl_rx_missed_beacon_notif;

        /* Rx handlers */
        handlers[REPLY_RX_PHY_CMD]              = iwl_rx_reply_rx_phy;
        handlers[REPLY_RX_MPDU_CMD]             = iwl_rx_reply_rx;

        /* block ack */
        handlers[REPLY_COMPRESSED_BA]           = iwlagn_rx_reply_compressed_ba;

        /* Set up hardware specific Rx handlers */
        priv->cfg->ops->lib->rx_handler_setup(priv);
}