/*
 * mac80211 <-> driver interface
 *
 * Copyright 2002-2005, Devicescape Software, Inc.
 * Copyright 2006-2007  Jiri Benc <jbenc@suse.cz>
 * Copyright 2007-2008  Johannes Berg <johannes@sipsolutions.net>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#ifndef MAC80211_H
#define MAC80211_H

#include <linux/kernel.h>
#include <linux/if_ether.h>
#include <linux/skbuff.h>
#include <linux/wireless.h>
#include <linux/device.h>
#include <linux/ieee80211.h>
#include <net/cfg80211.h>

/**
 * DOC: Introduction
 *
 * mac80211 is the Linux stack for 802.11 hardware that implements
 * only partial functionality in hard- or firmware. This document
 * defines the interface between mac80211 and low-level hardware
 * drivers.
 */

/**
 * DOC: Calling mac80211 from interrupts
 *
 * Only ieee80211_tx_status_irqsafe() and ieee80211_rx_irqsafe() can be
 * called in hardware interrupt context. The low-level driver must not call any
 * other functions in hardware interrupt context. If there is a need for such
 * call, the low-level driver should first ACK the interrupt and perform the
 * IEEE 802.11 code call after this, e.g. from a scheduled workqueue or even
 * tasklet function.
 *
 * NOTE: If the driver opts to use the _irqsafe() functions, it may not also
 *       use the non-IRQ-safe functions!
 */

/**
 * DOC: Warning
 *
 * If you're reading this document and not the header file itself, it will
 * be incomplete because not all documentation has been converted yet.
 */

/**
 * DOC: Frame format
 *
 * As a general rule, when frames are passed between mac80211 and the driver,
 * they start with the IEEE 802.11 header and include the same octets that are
 * sent over the air except for the FCS which should be calculated by the
 * hardware.
 *
 * There are, however, various exceptions to this rule for advanced features:
 *
 * The first exception is for hardware encryption and decryption offload
 * where the IV/ICV may or may not be generated in hardware.
 *
 * Secondly, when the hardware handles fragmentation, the frame handed to
 * the driver from mac80211 is the MSDU, not the MPDU.
 *
 * Finally, for received frames, the driver is able to indicate that it has
 * filled a radiotap header and put that in front of the frame; if it does
 * not do so then mac80211 may add this under certain circumstances.
 */

/**
 * DOC: mac80211 workqueue
 *
 * mac80211 provides its own workqueue for drivers and internal mac80211 use.
 * The workqueue is a single threaded workqueue and can only be accessed by
 * helpers for sanity checking. Drivers must ensure all work added onto the
 * mac80211 workqueue should be cancelled on the driver stop() callback.
 *
 * mac80211 will flushed the workqueue upon interface removal and during
 * suspend.
 *
 * All work performed on the mac80211 workqueue must not acquire the RTNL lock.
 *
 */

/**
 * enum ieee80211_max_queues - maximum number of queues
 *
 * @IEEE80211_MAX_QUEUES: Maximum number of regular device queues.
 */
enum ieee80211_max_queues {
        IEEE80211_MAX_QUEUES =          4,
};

/**
 * struct ieee80211_tx_queue_params - transmit queue configuration
 *
 * The information provided in this structure is required for QoS
 * transmit queue configuration. Cf. IEEE 802.11 7.3.2.29.
 *
 * @aifs: arbitration interframe space [0..255]
 * @cw_min: minimum contention window [a value of the form
 *      2^n-1 in the range 1..32767]
 * @cw_max: maximum contention window [like @cw_min]
 * @txop: maximum burst time in units of 32 usecs, 0 meaning disabled
 */
struct ieee80211_tx_queue_params {
        u16 txop;
        u16 cw_min;
        u16 cw_max;
        u8 aifs;
};

/**
 * struct ieee80211_tx_queue_stats - transmit queue statistics
 *
 * @len: number of packets in queue
 * @limit: queue length limit
 * @count: number of frames sent
 */
struct ieee80211_tx_queue_stats {
        unsigned int len;
        unsigned int limit;
        unsigned int count;
};

struct ieee80211_low_level_stats {
        unsigned int dot11ACKFailureCount;
        unsigned int dot11RTSFailureCount;
        unsigned int dot11FCSErrorCount;
        unsigned int dot11RTSSuccessCount;
};

/**
 * enum ieee80211_bss_change - BSS change notification flags
 *
 * These flags are used with the bss_info_changed() callback
 * to indicate which BSS parameter changed.
 *
 * @BSS_CHANGED_ASSOC: association status changed (associated/disassociated),
 *      also implies a change in the AID.
 * @BSS_CHANGED_ERP_CTS_PROT: CTS protection changed
 * @BSS_CHANGED_ERP_PREAMBLE: preamble changed
 * @BSS_CHANGED_ERP_SLOT: slot timing changed
 * @BSS_CHANGED_HT: 802.11n parameters changed
 * @BSS_CHANGED_BASIC_RATES: Basic rateset changed
 * @BSS_CHANGED_BEACON_INT: Beacon interval changed
 * @BSS_CHANGED_BSSID: BSSID changed, for whatever
 *      reason (IBSS and managed mode)
 * @BSS_CHANGED_BEACON: Beacon data changed, retrieve
 *      new beacon (beaconing modes)
 * @BSS_CHANGED_BEACON_ENABLED: Beaconing should be
 *      enabled/disabled (beaconing modes)
 */
enum ieee80211_bss_change {
        BSS_CHANGED_ASSOC               = 1<<0,
        BSS_CHANGED_ERP_CTS_PROT        = 1<<1,
        BSS_CHANGED_ERP_PREAMBLE        = 1<<2,
        BSS_CHANGED_ERP_SLOT            = 1<<3,
        BSS_CHANGED_HT                  = 1<<4,
        BSS_CHANGED_BASIC_RATES         = 1<<5,
        BSS_CHANGED_BEACON_INT          = 1<<6,
        BSS_CHANGED_BSSID               = 1<<7,
        BSS_CHANGED_BEACON              = 1<<8,
        BSS_CHANGED_BEACON_ENABLED      = 1<<9,
};

/**
 * struct ieee80211_bss_conf - holds the BSS's changing parameters
 *
 * This structure keeps information about a BSS (and an association
 * to that BSS) that can change during the lifetime of the BSS.
 *
 * @assoc: association status
 * @aid: association ID number, valid only when @assoc is true
 * @use_cts_prot: use CTS protection
 * @use_short_preamble: use 802.11b short preamble;
 *      if the hardware cannot handle this it must set the
 *      IEEE80211_HW_2GHZ_SHORT_PREAMBLE_INCAPABLE hardware flag
 * @use_short_slot: use short slot time (only relevant for ERP);
 *      if the hardware cannot handle this it must set the
 *      IEEE80211_HW_2GHZ_SHORT_SLOT_INCAPABLE hardware flag
 * @dtim_period: num of beacons before the next DTIM, for PSM
 * @timestamp: beacon timestamp
 * @beacon_int: beacon interval
 * @assoc_capability: capabilities taken from assoc resp
 * @basic_rates: bitmap of basic rates, each bit stands for an
 *      index into the rate table configured by the driver in
 *      the current band.
 * @bssid: The BSSID for this BSS
 * @enable_beacon: whether beaconing should be enabled or not
 * @ht_operation_mode: HT operation mode (like in &struct ieee80211_ht_info).
 *      This field is only valid when the channel type is one of the HT types.
 */
struct ieee80211_bss_conf {
        const u8 *bssid;
        /* association related data */
        bool assoc;
        u16 aid;
        /* erp related data */
        bool use_cts_prot;
        bool use_short_preamble;
        bool use_short_slot;
        bool enable_beacon;
        u8 dtim_period;
        u16 beacon_int;
        u16 assoc_capability;
        u64 timestamp;
        u32 basic_rates;
        u16 ht_operation_mode;
};

/**
 * enum mac80211_tx_control_flags - flags to describe transmission information/status
 *
 * These flags are used with the @flags member of &ieee80211_tx_info.
 *
 * @IEEE80211_TX_CTL_REQ_TX_STATUS: request TX status callback for this frame.
 * @IEEE80211_TX_CTL_ASSIGN_SEQ: The driver has to assign a sequence
 *      number to this frame, taking care of not overwriting the fragment
 *      number and increasing the sequence number only when the
 *      IEEE80211_TX_CTL_FIRST_FRAGMENT flag is set. mac80211 will properly
 *      assign sequence numbers to QoS-data frames but cannot do so correctly
 *      for non-QoS-data and management frames because beacons need them from
 *      that counter as well and mac80211 cannot guarantee proper sequencing.
 *      If this flag is set, the driver should instruct the hardware to
 *      assign a sequence number to the frame or assign one itself. Cf. IEEE
 *      802.11-2007 7.1.3.4.1 paragraph 3. This flag will always be set for
 *      beacons and always be clear for frames without a sequence number field.
 * @IEEE80211_TX_CTL_NO_ACK: tell the low level not to wait for an ack
 * @IEEE80211_TX_CTL_CLEAR_PS_FILT: clear powersave filter for destination
 *      station
 * @IEEE80211_TX_CTL_FIRST_FRAGMENT: this is a first fragment of the frame
 * @IEEE80211_TX_CTL_SEND_AFTER_DTIM: send this frame after DTIM beacon
 * @IEEE80211_TX_CTL_AMPDU: this frame should be sent as part of an A-MPDU
 * @IEEE80211_TX_CTL_INJECTED: Frame was injected, internal to mac80211.
 * @IEEE80211_TX_STAT_TX_FILTERED: The frame was not transmitted
 *      because the destination STA was in powersave mode. Note that to
 *      avoid race conditions, the filter must be set by the hardware or
 *      firmware upon receiving a frame that indicates that the station
 *      went to sleep (must be done on device to filter frames already on
 *      the queue) and may only be unset after mac80211 gives the OK for
 *      that by setting the IEEE80211_TX_CTL_CLEAR_PS_FILT (see above),
 *      since only then is it guaranteed that no more frames are in the
 *      hardware queue.
 * @IEEE80211_TX_STAT_ACK: Frame was acknowledged
 * @IEEE80211_TX_STAT_AMPDU: The frame was aggregated, so status
 *      is for the whole aggregation.
 * @IEEE80211_TX_STAT_AMPDU_NO_BACK: no block ack was returned,
 *      so consider using block ack request (BAR).
 * @IEEE80211_TX_CTL_RATE_CTRL_PROBE: internal to mac80211, can be
 *      set by rate control algorithms to indicate probe rate, will
 *      be cleared for fragmented frames (except on the last fragment)
 * @IEEE80211_TX_INTFL_RCALGO: mac80211 internal flag, do not test or
 *      set this flag in the driver; indicates that the rate control
 *      algorithm was used and should be notified of TX status
 * @IEEE80211_TX_INTFL_NEED_TXPROCESSING: completely internal to mac80211,
 *      used to indicate that a pending frame requires TX processing before
 *      it can be sent out.
 * @IEEE80211_TX_INTFL_RETRIED: completely internal to mac80211,
 *      used to indicate that a frame was already retried due to PS
 * @IEEE80211_TX_INTFL_DONT_ENCRYPT: completely internal to mac80211,
 *      used to indicate frame should not be encrypted
 * @IEEE80211_TX_CTL_PSPOLL_RESPONSE: (internal?)
 *      This frame is a response to a PS-poll frame and should be sent
 *      although the station is in powersave mode.
 * @IEEE80211_TX_CTL_MORE_FRAMES: More frames will be passed to the
 *      transmit function after the current frame, this can be used
 *      by drivers to kick the DMA queue only if unset or when the
 *      queue gets full.
 */
enum mac80211_tx_control_flags {
        IEEE80211_TX_CTL_REQ_TX_STATUS          = BIT(0),
        IEEE80211_TX_CTL_ASSIGN_SEQ             = BIT(1),
        IEEE80211_TX_CTL_NO_ACK                 = BIT(2),
        IEEE80211_TX_CTL_CLEAR_PS_FILT          = BIT(3),
        IEEE80211_TX_CTL_FIRST_FRAGMENT         = BIT(4),
        IEEE80211_TX_CTL_SEND_AFTER_DTIM        = BIT(5),
        IEEE80211_TX_CTL_AMPDU                  = BIT(6),
        IEEE80211_TX_CTL_INJECTED               = BIT(7),
        IEEE80211_TX_STAT_TX_FILTERED           = BIT(8),
        IEEE80211_TX_STAT_ACK                   = BIT(9),
        IEEE80211_TX_STAT_AMPDU                 = BIT(10),
        IEEE80211_TX_STAT_AMPDU_NO_BACK         = BIT(11),
        IEEE80211_TX_CTL_RATE_CTRL_PROBE        = BIT(12),
        IEEE80211_TX_INTFL_RCALGO               = BIT(13),
        IEEE80211_TX_INTFL_NEED_TXPROCESSING    = BIT(14),
        IEEE80211_TX_INTFL_RETRIED              = BIT(15),
        IEEE80211_TX_INTFL_DONT_ENCRYPT         = BIT(16),
        IEEE80211_TX_CTL_PSPOLL_RESPONSE        = BIT(17),
        IEEE80211_TX_CTL_MORE_FRAMES            = BIT(18),
};

/**
 * enum mac80211_rate_control_flags - per-rate flags set by the
 *      Rate Control algorithm.
 *
 * These flags are set by the Rate control algorithm for each rate during tx,
 * in the @flags member of struct ieee80211_tx_rate.
 *
 * @IEEE80211_TX_RC_USE_RTS_CTS: Use RTS/CTS exchange for this rate.
 * @IEEE80211_TX_RC_USE_CTS_PROTECT: CTS-to-self protection is required.
 *      This is set if the current BSS requires ERP protection.
 * @IEEE80211_TX_RC_USE_SHORT_PREAMBLE: Use short preamble.
 * @IEEE80211_TX_RC_MCS: HT rate.
 * @IEEE80211_TX_RC_GREEN_FIELD: Indicates whether this rate should be used in
 *      Greenfield mode.
 * @IEEE80211_TX_RC_40_MHZ_WIDTH: Indicates if the Channel Width should be 40 MHz.
 * @IEEE80211_TX_RC_DUP_DATA: The frame should be transmitted on both of the
 *      adjacent 20 MHz channels, if the current channel type is
 *      NL80211_CHAN_HT40MINUS or NL80211_CHAN_HT40PLUS.
 * @IEEE80211_TX_RC_SHORT_GI: Short Guard interval should be used for this rate.
 */
enum mac80211_rate_control_flags {
        IEEE80211_TX_RC_USE_RTS_CTS             = BIT(0),
        IEEE80211_TX_RC_USE_CTS_PROTECT         = BIT(1),
        IEEE80211_TX_RC_USE_SHORT_PREAMBLE      = BIT(2),

        /* rate index is an MCS rate number instead of an index */
        IEEE80211_TX_RC_MCS                     = BIT(3),
        IEEE80211_TX_RC_GREEN_FIELD             = BIT(4),
        IEEE80211_TX_RC_40_MHZ_WIDTH            = BIT(5),
        IEEE80211_TX_RC_DUP_DATA                = BIT(6),
        IEEE80211_TX_RC_SHORT_GI                = BIT(7),
};


/* there are 40 bytes if you don't need the rateset to be kept */
#define IEEE80211_TX_INFO_DRIVER_DATA_SIZE 40

/* if you do need the rateset, then you have less space */
#define IEEE80211_TX_INFO_RATE_DRIVER_DATA_SIZE 24

/* maximum number of rate stages */
#define IEEE80211_TX_MAX_RATES  5

/**
 * struct ieee80211_tx_rate - rate selection/status
 *
 * @idx: rate index to attempt to send with
 * @flags: rate control flags (&enum mac80211_rate_control_flags)
 * @count: number of tries in this rate before going to the next rate
 *
 * A value of -1 for @idx indicates an invalid rate and, if used
 * in an array of retry rates, that no more rates should be tried.
 *
 * When used for transmit status reporting, the driver should
 * always report the rate along with the flags it used.
 *
 * &struct ieee80211_tx_info contains an array of these structs
 * in the control information, and it will be filled by the rate
 * control algorithm according to what should be sent. For example,
 * if this array contains, in the format { <idx>, <count> } the
 * information
 *    { 3, 2 }, { 2, 2 }, { 1, 4 }, { -1, 0 }, { -1, 0 }
 * then this means that the frame should be transmitted
 * up to twice at rate 3, up to twice at rate 2, and up to four
 * times at rate 1 if it doesn't get acknowledged. Say it gets
 * acknowledged by the peer after the fifth attempt, the status
 * information should then contain
 *   { 3, 2 }, { 2, 2 }, { 1, 1 }, { -1, 0 } ...
 * since it was transmitted twice at rate 3, twice at rate 2
 * and once at rate 1 after which we received an acknowledgement.
 */
struct ieee80211_tx_rate {
        s8 idx;
        u8 count;
        u8 flags;
} __attribute__((packed));

/**
 * struct ieee80211_tx_info - skb transmit information
 *
 * This structure is placed in skb->cb for three uses:
 *  (1) mac80211 TX control - mac80211 tells the driver what to do
 *  (2) driver internal use (if applicable)
 *  (3) TX status information - driver tells mac80211 what happened
 *
 * The TX control's sta pointer is only valid during the ->tx call,
 * it may be NULL.
 *
 * @flags: transmit info flags, defined above
 * @band: the band to transmit on (use for checking for races)
 * @antenna_sel_tx: antenna to use, 0 for automatic diversity
 * @pad: padding, ignore
 * @control: union for control data
 * @status: union for status data
 * @driver_data: array of driver_data pointers
 * @ampdu_ack_len: number of aggregated frames.
 *      relevant only if IEEE80211_TX_STATUS_AMPDU was set.
 * @ampdu_ack_map: block ack bit map for the aggregation.
 *      relevant only if IEEE80211_TX_STATUS_AMPDU was set.
 * @ack_signal: signal strength of the ACK frame
 */
struct ieee80211_tx_info {
        /* common information */
        u32 flags;
        u8 band;

        u8 antenna_sel_tx;

        /* 2 byte hole */
        u8 pad[2];

        union {
                struct {
                        union {
                                /* rate control */
                                struct {
                                        struct ieee80211_tx_rate rates[
                                                IEEE80211_TX_MAX_RATES];
                                        s8 rts_cts_rate_idx;
                                };
                                /* only needed before rate control */
                                unsigned long jiffies;
                        };
                        /* NB: vif can be NULL for injected frames */
                        struct ieee80211_vif *vif;
                        struct ieee80211_key_conf *hw_key;
                        struct ieee80211_sta *sta;
                } control;
                struct {
                        struct ieee80211_tx_rate rates[IEEE80211_TX_MAX_RATES];
                        u8 ampdu_ack_len;
                        u64 ampdu_ack_map;
                        int ack_signal;
                        /* 8 bytes free */
                } status;
                struct {
                        struct ieee80211_tx_rate driver_rates[
                                IEEE80211_TX_MAX_RATES];
                        void *rate_driver_data[
                                IEEE80211_TX_INFO_RATE_DRIVER_DATA_SIZE / sizeof(void *)];
                };
                void *driver_data[
                        IEEE80211_TX_INFO_DRIVER_DATA_SIZE / sizeof(void *)];
        };
};

static inline struct ieee80211_tx_info *IEEE80211_SKB_CB(struct sk_buff *skb)
{
        return (struct ieee80211_tx_info *)skb->cb;
}

static inline struct ieee80211_rx_status *IEEE80211_SKB_RXCB(struct sk_buff *skb)
{
        return (struct ieee80211_rx_status *)skb->cb;
}

/**
 * ieee80211_tx_info_clear_status - clear TX status
 *
 * @info: The &struct ieee80211_tx_info to be cleared.
 *
 * When the driver passes an skb back to mac80211, it must report
 * a number of things in TX status. This function clears everything
 * in the TX status but the rate control information (it does clear
 * the count since you need to fill that in anyway).
 *
 * NOTE: You can only use this function if you do NOT use
 *       info->driver_data! Use info->rate_driver_data
 *       instead if you need only the less space that allows.
 */
static inline void
ieee80211_tx_info_clear_status(struct ieee80211_tx_info *info)
{
        int i;

        BUILD_BUG_ON(offsetof(struct ieee80211_tx_info, status.rates) !=
                     offsetof(struct ieee80211_tx_info, control.rates));
        BUILD_BUG_ON(offsetof(struct ieee80211_tx_info, status.rates) !=
                     offsetof(struct ieee80211_tx_info, driver_rates));
        BUILD_BUG_ON(offsetof(struct ieee80211_tx_info, status.rates) != 8);
        /* clear the rate counts */
        for (i = 0; i < IEEE80211_TX_MAX_RATES; i++)
                info->status.rates[i].count = 0;

        BUILD_BUG_ON(
            offsetof(struct ieee80211_tx_info, status.ampdu_ack_len) != 23);
        memset(&info->status.ampdu_ack_len, 0,
               sizeof(struct ieee80211_tx_info) -
               offsetof(struct ieee80211_tx_info, status.ampdu_ack_len));
}


/**
 * enum mac80211_rx_flags - receive flags
 *
 * These flags are used with the @flag member of &struct ieee80211_rx_status.
 * @RX_FLAG_MMIC_ERROR: Michael MIC error was reported on this frame.
 *      Use together with %RX_FLAG_MMIC_STRIPPED.
 * @RX_FLAG_DECRYPTED: This frame was decrypted in hardware.
 * @RX_FLAG_RADIOTAP: This frame starts with a radiotap header.
 * @RX_FLAG_MMIC_STRIPPED: the Michael MIC is stripped off this frame,
 *      verification has been done by the hardware.
 * @RX_FLAG_IV_STRIPPED: The IV/ICV are stripped from this frame.
 *      If this flag is set, the stack cannot do any replay detection
 *      hence the driver or hardware will have to do that.
 * @RX_FLAG_FAILED_FCS_CRC: Set this flag if the FCS check failed on
 *      the frame.
 * @RX_FLAG_FAILED_PLCP_CRC: Set this flag if the PCLP check failed on
 *      the frame.
 * @RX_FLAG_TSFT: The timestamp passed in the RX status (@mactime field)
 *      is valid. This is useful in monitor mode and necessary for beacon frames
 *      to enable IBSS merging.
 * @RX_FLAG_SHORTPRE: Short preamble was used for this frame
 * @RX_FLAG_HT: HT MCS was used and rate_idx is MCS index
 * @RX_FLAG_40MHZ: HT40 (40 MHz) was used
 * @RX_FLAG_SHORT_GI: Short guard interval was used
 */
enum mac80211_rx_flags {
        RX_FLAG_MMIC_ERROR      = 1<<0,
        RX_FLAG_DECRYPTED       = 1<<1,
        RX_FLAG_RADIOTAP        = 1<<2,
        RX_FLAG_MMIC_STRIPPED   = 1<<3,
        RX_FLAG_IV_STRIPPED     = 1<<4,
        RX_FLAG_FAILED_FCS_CRC  = 1<<5,
        RX_FLAG_FAILED_PLCP_CRC = 1<<6,
        RX_FLAG_TSFT            = 1<<7,
        RX_FLAG_SHORTPRE        = 1<<8,
        RX_FLAG_HT              = 1<<9,
        RX_FLAG_40MHZ           = 1<<10,
        RX_FLAG_SHORT_GI        = 1<<11,
};

/**
 * struct ieee80211_rx_status - receive status
 *
 * The low-level driver should provide this information (the subset
 * supported by hardware) to the 802.11 code with each received
 * frame, in the skb's control buffer (cb).
 *
 * @mactime: value in microseconds of the 64-bit Time Synchronization Function
 *      (TSF) timer when the first data symbol (MPDU) arrived at the hardware.
 * @band: the active band when this frame was received
 * @freq: frequency the radio was tuned to when receiving this frame, in MHz
 * @signal: signal strength when receiving this frame, either in dBm, in dB or
 *      unspecified depending on the hardware capabilities flags
 *      @IEEE80211_HW_SIGNAL_*
 * @noise: noise when receiving this frame, in dBm.
 * @qual: overall signal quality indication, in percent (0-100).
 * @antenna: antenna used
 * @rate_idx: index of data rate into band's supported rates or MCS index if
 *      HT rates are use (RX_FLAG_HT)
 * @flag: %RX_FLAG_*
 */
struct ieee80211_rx_status {
        u64 mactime;
        enum ieee80211_band band;
        int freq;
        int signal;
        int noise;
        int qual;
        int antenna;
        int rate_idx;
        int flag;
};

/**
 * enum ieee80211_conf_flags - configuration flags
 *
 * Flags to define PHY configuration options
 *
 * @IEEE80211_CONF_RADIOTAP: add radiotap header at receive time (if supported)
 * @IEEE80211_CONF_PS: Enable 802.11 power save mode (managed mode only)
 * @IEEE80211_CONF_IDLE: The device is running, but idle; if the flag is set
 *      the driver should be prepared to handle configuration requests but
 *      may turn the device off as much as possible. Typically, this flag will
 *      be set when an interface is set UP but not associated or scanning, but
 *      it can also be unset in that case when monitor interfaces are active.
 */
enum ieee80211_conf_flags {
        IEEE80211_CONF_RADIOTAP         = (1<<0),
        IEEE80211_CONF_PS               = (1<<1),
        IEEE80211_CONF_IDLE             = (1<<2),
};


/**
 * enum ieee80211_conf_changed - denotes which configuration changed
 *
 * @IEEE80211_CONF_CHANGE_LISTEN_INTERVAL: the listen interval changed
 * @IEEE80211_CONF_CHANGE_RADIOTAP: the radiotap flag changed
 * @IEEE80211_CONF_CHANGE_PS: the PS flag or dynamic PS timeout changed
 * @IEEE80211_CONF_CHANGE_POWER: the TX power changed
 * @IEEE80211_CONF_CHANGE_CHANNEL: the channel/channel_type changed
 * @IEEE80211_CONF_CHANGE_RETRY_LIMITS: retry limits changed
 * @IEEE80211_CONF_CHANGE_IDLE: Idle flag changed
 */
enum ieee80211_conf_changed {
        IEEE80211_CONF_CHANGE_LISTEN_INTERVAL   = BIT(2),
        IEEE80211_CONF_CHANGE_RADIOTAP          = BIT(3),
        IEEE80211_CONF_CHANGE_PS                = BIT(4),
        IEEE80211_CONF_CHANGE_POWER             = BIT(5),
        IEEE80211_CONF_CHANGE_CHANNEL           = BIT(6),
        IEEE80211_CONF_CHANGE_RETRY_LIMITS      = BIT(7),
        IEEE80211_CONF_CHANGE_IDLE              = BIT(8),
};

/**
 * struct ieee80211_conf - configuration of the device
 *
 * This struct indicates how the driver shall configure the hardware.
 *
 * @flags: configuration flags defined above
 *
 * @listen_interval: listen interval in units of beacon interval
 * @max_sleep_period: the maximum number of beacon intervals to sleep for
 *      before checking the beacon for a TIM bit (managed mode only); this
 *      value will be only achievable between DTIM frames, the hardware
 *      needs to check for the multicast traffic bit in DTIM beacons.
 *      This variable is valid only when the CONF_PS flag is set.
 * @dynamic_ps_timeout: The dynamic powersave timeout (in ms), see the
 *      powersave documentation below. This variable is valid only when
 *      the CONF_PS flag is set.
 *
 * @power_level: requested transmit power (in dBm)
 *
 * @channel: the channel to tune to
 * @channel_type: the channel (HT) type
 *
 * @long_frame_max_tx_count: Maximum number of transmissions for a "long" frame
 *    (a frame not RTS protected), called "dot11LongRetryLimit" in 802.11,
 *    but actually means the number of transmissions not the number of retries
 * @short_frame_max_tx_count: Maximum number of transmissions for a "short"
 *    frame, called "dot11ShortRetryLimit" in 802.11, but actually means the
 *    number of transmissions not the number of retries
 */
struct ieee80211_conf {
        u32 flags;
        int power_level, dynamic_ps_timeout;
        int max_sleep_period;

        u16 listen_interval;

        u8 long_frame_max_tx_count, short_frame_max_tx_count;

        struct ieee80211_channel *channel;
        enum nl80211_channel_type channel_type;
};

/**
 * struct ieee80211_vif - per-interface data
 *
 * Data in this structure is continually present for driver
 * use during the life of a virtual interface.
 *
 * @type: type of this virtual interface
 * @bss_conf: BSS configuration for this interface, either our own
 *      or the BSS we're associated to
 * @drv_priv: data area for driver use, will always be aligned to
 *      sizeof(void *).
 */
struct ieee80211_vif {
        enum nl80211_iftype type;
        struct ieee80211_bss_conf bss_conf;
        /* must be last */
        u8 drv_priv[0] __attribute__((__aligned__(sizeof(void *))));
};

static inline bool ieee80211_vif_is_mesh(struct ieee80211_vif *vif)
{
#ifdef CONFIG_MAC80211_MESH
        return vif->type == NL80211_IFTYPE_MESH_POINT;
#endif
        return false;
}

/**
 * struct ieee80211_if_init_conf - initial configuration of an interface
 *
 * @vif: pointer to a driver-use per-interface structure. The pointer
 *      itself is also used for various functions including
 *      ieee80211_beacon_get() and ieee80211_get_buffered_bc().
 * @type: one of &enum nl80211_iftype constants. Determines the type of
 *      added/removed interface.
 * @mac_addr: pointer to MAC address of the interface. This pointer is valid
 *      until the interface is removed (i.e. it cannot be used after
 *      remove_interface() callback was called for this interface).
 *
 * This structure is used in add_interface() and remove_interface()
 * callbacks of &struct ieee80211_hw.
 *
 * When you allow multiple interfaces to be added to your PHY, take care
 * that the hardware can actually handle multiple MAC addresses. However,
 * also take care that when there's no interface left with mac_addr != %NULL
 * you remove the MAC address from the device to avoid acknowledging packets
 * in pure monitor mode.
 */
struct ieee80211_if_init_conf {
        enum nl80211_iftype type;
        struct ieee80211_vif *vif;
        void *mac_addr;
};

/**
 * enum ieee80211_key_alg - key algorithm
 * @ALG_WEP: WEP40 or WEP104
 * @ALG_TKIP: TKIP
 * @ALG_CCMP: CCMP (AES)
 * @ALG_AES_CMAC: AES-128-CMAC
 */
enum ieee80211_key_alg {
        ALG_WEP,
        ALG_TKIP,
        ALG_CCMP,
        ALG_AES_CMAC,
};

/**
 * enum ieee80211_key_flags - key flags
 *
 * These flags are used for communication about keys between the driver
 * and mac80211, with the @flags parameter of &struct ieee80211_key_conf.
 *
 * @IEEE80211_KEY_FLAG_WMM_STA: Set by mac80211, this flag indicates
 *      that the STA this key will be used with could be using QoS.
 * @IEEE80211_KEY_FLAG_GENERATE_IV: This flag should be set by the
 *      driver to indicate that it requires IV generation for this
 *      particular key.
 * @IEEE80211_KEY_FLAG_GENERATE_MMIC: This flag should be set by
 *      the driver for a TKIP key if it requires Michael MIC
 *      generation in software.
 * @IEEE80211_KEY_FLAG_PAIRWISE: Set by mac80211, this flag indicates
 *      that the key is pairwise rather then a shared key.
 * @IEEE80211_KEY_FLAG_SW_MGMT: This flag should be set by the driver for a
 *      CCMP key if it requires CCMP encryption of management frames (MFP) to
 *      be done in software.
 */
enum ieee80211_key_flags {
        IEEE80211_KEY_FLAG_WMM_STA      = 1<<0,
        IEEE80211_KEY_FLAG_GENERATE_IV  = 1<<1,
        IEEE80211_KEY_FLAG_GENERATE_MMIC= 1<<2,
        IEEE80211_KEY_FLAG_PAIRWISE     = 1<<3,
        IEEE80211_KEY_FLAG_SW_MGMT      = 1<<4,
};

/**
 * struct ieee80211_key_conf - key information
 *
 * This key information is given by mac80211 to the driver by
 * the set_key() callback in &struct ieee80211_ops.
 *
 * @hw_key_idx: To be set by the driver, this is the key index the driver
 *      wants to be given when a frame is transmitted and needs to be
 *      encrypted in hardware.
 * @alg: The key algorithm.
 * @flags: key flags, see &enum ieee80211_key_flags.
 * @keyidx: the key index (0-3)
 * @keylen: key material length
 * @key: key material. For ALG_TKIP the key is encoded as a 256-bit (32 byte)
 *      data block:
 *      - Temporal Encryption Key (128 bits)
 *      - Temporal Authenticator Tx MIC Key (64 bits)
 *      - Temporal Authenticator Rx MIC Key (64 bits)
 * @icv_len: The ICV length for this key type
 * @iv_len: The IV length for this key type
 */
struct ieee80211_key_conf {
        enum ieee80211_key_alg alg;
        u8 icv_len;
        u8 iv_len;
        u8 hw_key_idx;
        u8 flags;
        s8 keyidx;
        u8 keylen;
        u8 key[0];
};

/**
 * enum set_key_cmd - key command
 *
 * Used with the set_key() callback in &struct ieee80211_ops, this
 * indicates whether a key is being removed or added.
 *
 * @SET_KEY: a key is set
 * @DISABLE_KEY: a key must be disabled
 */
enum set_key_cmd {
        SET_KEY, DISABLE_KEY,
};

/**
 * struct ieee80211_sta - station table entry
 *
 * A station table entry represents a station we are possibly
 * communicating with. Since stations are RCU-managed in
 * mac80211, any ieee80211_sta pointer you get access to must
 * either be protected by rcu_read_lock() explicitly or implicitly,
 * or you must take good care to not use such a pointer after a
 * call to your sta_notify callback that removed it.
 *
 * @addr: MAC address
 * @aid: AID we assigned to the station if we're an AP
 * @supp_rates: Bitmap of supported rates (per band)
 * @ht_cap: HT capabilities of this STA; restricted to our own TX capabilities
 * @drv_priv: data area for driver use, will always be aligned to
 *      sizeof(void *), size is determined in hw information.
 */
struct ieee80211_sta {
        u32 supp_rates[IEEE80211_NUM_BANDS];
        u8 addr[ETH_ALEN];
        u16 aid;
        struct ieee80211_sta_ht_cap ht_cap;

        /* must be last */
        u8 drv_priv[0] __attribute__((__aligned__(sizeof(void *))));
};

/**
 * enum sta_notify_cmd - sta notify command
 *
 * Used with the sta_notify() callback in &struct ieee80211_ops, this
 * indicates addition and removal of a station to station table,
 * or if a associated station made a power state transition.
 *
 * @STA_NOTIFY_ADD: a station was added to the station table
 * @STA_NOTIFY_REMOVE: a station being removed from the station table
 * @STA_NOTIFY_SLEEP: a station is now sleeping
 * @STA_NOTIFY_AWAKE: a sleeping station woke up
 */
enum sta_notify_cmd {
        STA_NOTIFY_ADD, STA_NOTIFY_REMOVE,
        STA_NOTIFY_SLEEP, STA_NOTIFY_AWAKE,
};

/**
 * enum ieee80211_tkip_key_type - get tkip key
 *
 * Used by drivers which need to get a tkip key for skb. Some drivers need a
 * phase 1 key, others need a phase 2 key. A single function allows the driver
 * to get the key, this enum indicates what type of key is required.
 *
 * @IEEE80211_TKIP_P1_KEY: the driver needs a phase 1 key
 * @IEEE80211_TKIP_P2_KEY: the driver needs a phase 2 key
 */
enum ieee80211_tkip_key_type {
        IEEE80211_TKIP_P1_KEY,
        IEEE80211_TKIP_P2_KEY,
};

/**
 * enum ieee80211_hw_flags - hardware flags
 *
 * These flags are used to indicate hardware capabilities to
 * the stack. Generally, flags here should have their meaning
 * done in a way that the simplest hardware doesn't need setting
 * any particular flags. There are some exceptions to this rule,
 * however, so you are advised to review these flags carefully.
 *
 * @IEEE80211_HW_RX_INCLUDES_FCS:
 *      Indicates that received frames passed to the stack include
 *      the FCS at the end.
 *
 * @IEEE80211_HW_HOST_BROADCAST_PS_BUFFERING:
 *      Some wireless LAN chipsets buffer broadcast/multicast frames
 *      for power saving stations in the hardware/firmware and others
 *      rely on the host system for such buffering. This option is used
 *      to configure the IEEE 802.11 upper layer to buffer broadcast and
 *      multicast frames when there are power saving stations so that
 *      the driver can fetch them with ieee80211_get_buffered_bc().
 *
 * @IEEE80211_HW_2GHZ_SHORT_SLOT_INCAPABLE:
 *      Hardware is not capable of short slot operation on the 2.4 GHz band.
 *
 * @IEEE80211_HW_2GHZ_SHORT_PREAMBLE_INCAPABLE:
 *      Hardware is not capable of receiving frames with short preamble on
 *      the 2.4 GHz band.
 *
 * @IEEE80211_HW_SIGNAL_UNSPEC:
 *      Hardware can provide signal values but we don't know its units. We
 *      expect values between 0 and @max_signal.
 *      If possible please provide dB or dBm instead.
 *
 * @IEEE80211_HW_SIGNAL_DBM:
 *      Hardware gives signal values in dBm, decibel difference from
 *      one milliwatt. This is the preferred method since it is standardized
 *      between different devices. @max_signal does not need to be set.
 *
 * @IEEE80211_HW_NOISE_DBM:
 *      Hardware can provide noise (radio interference) values in units dBm,
 *      decibel difference from one milliwatt.
 *
 * @IEEE80211_HW_SPECTRUM_MGMT:
 *      Hardware supports spectrum management defined in 802.11h
 *      Measurement, Channel Switch, Quieting, TPC
 *
 * @IEEE80211_HW_AMPDU_AGGREGATION:
 *      Hardware supports 11n A-MPDU aggregation.
 *
 * @IEEE80211_HW_SUPPORTS_PS:
 *      Hardware has power save support (i.e. can go to sleep).
 *
 * @IEEE80211_HW_PS_NULLFUNC_STACK:
 *      Hardware requires nullfunc frame handling in stack, implies
 *      stack support for dynamic PS.
 *
 * @IEEE80211_HW_SUPPORTS_DYNAMIC_PS:
 *      Hardware has support for dynamic PS.
 *
 * @IEEE80211_HW_MFP_CAPABLE:
 *      Hardware supports management frame protection (MFP, IEEE 802.11w).
 *
 * @IEEE80211_HW_BEACON_FILTER:
 *      Hardware supports dropping of irrelevant beacon frames to
 *      avoid waking up cpu.
 */
enum ieee80211_hw_flags {
        IEEE80211_HW_RX_INCLUDES_FCS                    = 1<<1,
        IEEE80211_HW_HOST_BROADCAST_PS_BUFFERING        = 1<<2,
        IEEE80211_HW_2GHZ_SHORT_SLOT_INCAPABLE          = 1<<3,
        IEEE80211_HW_2GHZ_SHORT_PREAMBLE_INCAPABLE      = 1<<4,
        IEEE80211_HW_SIGNAL_UNSPEC                      = 1<<5,
        IEEE80211_HW_SIGNAL_DBM                         = 1<<6,
        IEEE80211_HW_NOISE_DBM                          = 1<<7,
        IEEE80211_HW_SPECTRUM_MGMT                      = 1<<8,
        IEEE80211_HW_AMPDU_AGGREGATION                  = 1<<9,
        IEEE80211_HW_SUPPORTS_PS                        = 1<<10,
        IEEE80211_HW_PS_NULLFUNC_STACK                  = 1<<11,
        IEEE80211_HW_SUPPORTS_DYNAMIC_PS                = 1<<12,
        IEEE80211_HW_MFP_CAPABLE                        = 1<<13,
        IEEE80211_HW_BEACON_FILTER                      = 1<<14,
};

/**
 * struct ieee80211_hw - hardware information and state
 *
 * This structure contains the configuration and hardware
 * information for an 802.11 PHY.
 *
 * @wiphy: This points to the &struct wiphy allocated for this
 *      802.11 PHY. You must fill in the @perm_addr and @dev
 *      members of this structure using SET_IEEE80211_DEV()
 *      and SET_IEEE80211_PERM_ADDR(). Additionally, all supported
 *      bands (with channels, bitrates) are registered here.
 *
 * @conf: &struct ieee80211_conf, device configuration, don't use.
 *
 * @priv: pointer to private area that was allocated for driver use
 *      along with this structure.
 *
 * @flags: hardware flags, see &enum ieee80211_hw_flags.
 *
 * @extra_tx_headroom: headroom to reserve in each transmit skb
 *      for use by the driver (e.g. for transmit headers.)
 *
 * @channel_change_time: time (in microseconds) it takes to change channels.
 *
 * @max_signal: Maximum value for signal (rssi) in RX information, used
 *     only when @IEEE80211_HW_SIGNAL_UNSPEC or @IEEE80211_HW_SIGNAL_DB
 *
 * @max_listen_interval: max listen interval in units of beacon interval
 *     that HW supports
 *
 * @queues: number of available hardware transmit queues for
 *      data packets. WMM/QoS requires at least four, these
 *      queues need to have configurable access parameters.
 *
 * @rate_control_algorithm: rate control algorithm for this hardware.
 *      If unset (NULL), the default algorithm will be used. Must be
 *      set before calling ieee80211_register_hw().
 *
 * @vif_data_size: size (in bytes) of the drv_priv data area
 *      within &struct ieee80211_vif.
 * @sta_data_size: size (in bytes) of the drv_priv data area
 *      within &struct ieee80211_sta.
 *
 * @max_rates: maximum number of alternate rate retry stages
 * @max_rate_tries: maximum number of tries for each stage
 */
struct ieee80211_hw {
        struct ieee80211_conf conf;
        struct wiphy *wiphy;
        const char *rate_control_algorithm;
        void *priv;
        u32 flags;
        unsigned int extra_tx_headroom;
        int channel_change_time;
        int vif_data_size;
        int sta_data_size;
        u16 queues;
        u16 max_listen_interval;
        s8 max_signal;
        u8 max_rates;
        u8 max_rate_tries;
};

/**
 * wiphy_to_ieee80211_hw - return a mac80211 driver hw struct from a wiphy
 *
 * @wiphy: the &struct wiphy which we want to query
 *
 * mac80211 drivers can use this to get to their respective
 * &struct ieee80211_hw. Drivers wishing to get to their own private
 * structure can then access it via hw->priv. Note that mac802111 drivers should
 * not use wiphy_priv() to try to get their private driver structure as this

 * is already used internally by mac80211.
 */
struct ieee80211_hw *wiphy_to_ieee80211_hw(struct wiphy *wiphy);

/**
 * SET_IEEE80211_DEV - set device for 802.11 hardware
 *
 * @hw: the &struct ieee80211_hw to set the device for
 * @dev: the &struct device of this 802.11 device
 */
static inline void SET_IEEE80211_DEV(struct ieee80211_hw *hw, struct device *dev)
{
        set_wiphy_dev(hw->wiphy, dev);
}

/**
 * SET_IEEE80211_PERM_ADDR - set the permanent MAC address for 802.11 hardware
 *
 * @hw: the &struct ieee80211_hw to set the MAC address for
 * @addr: the address to set
 */
static inline void SET_IEEE80211_PERM_ADDR(struct ieee80211_hw *hw, u8 *addr)
{
        memcpy(hw->wiphy->perm_addr, addr, ETH_ALEN);
}

static inline struct ieee80211_rate *
ieee80211_get_tx_rate(const struct ieee80211_hw *hw,
                      const struct ieee80211_tx_info *c)
{
        if (WARN_ON(c->control.rates[0].idx < 0))
                return NULL;
        return &hw->wiphy->bands[c->band]->bitrates[c->control.rates[0].idx];
}

static inline struct ieee80211_rate *
ieee80211_get_rts_cts_rate(const struct ieee80211_hw *hw,
                           const struct ieee80211_tx_info *c)
{
        if (c->control.rts_cts_rate_idx < 0)
                return NULL;
        return &hw->wiphy->bands[c->band]->bitrates[c->control.rts_cts_rate_idx];
}

static inline struct ieee80211_rate *
ieee80211_get_alt_retry_rate(const struct ieee80211_hw *hw,
                             const struct ieee80211_tx_info *c, int idx)
{
        if (c->control.rates[idx + 1].idx < 0)
                return NULL;
        return &hw->wiphy->bands[c->band]->bitrates[c->control.rates[idx + 1].idx];
}

/**
 * DOC: Hardware crypto acceleration
 *
 * mac80211 is capable of taking advantage of many hardware
 * acceleration designs for encryption and decryption operations.
 *
 * The set_key() callback in the &struct ieee80211_ops for a given
 * device is called to enable hardware acceleration of encryption and
 * decryption. The callback takes a @sta parameter that will be NULL
 * for default keys or keys used for transmission only, or point to
 * the station information for the peer for individual keys.
 * Multiple transmission keys with the same key index may be used when
 * VLANs are configured for an access point.
 *
 * When transmitting, the TX control data will use the @hw_key_idx
 * selected by the driver by modifying the &struct ieee80211_key_conf
 * pointed to by the @key parameter to the set_key() function.
 *
 * The set_key() call for the %SET_KEY command should return 0 if
 * the key is now in use, -%EOPNOTSUPP or -%ENOSPC if it couldn't be
 * added; if you return 0 then hw_key_idx must be assigned to the
 * hardware key index, you are free to use the full u8 range.
 *
 * When the cmd is %DISABLE_KEY then it must succeed.
 *
 * Note that it is permissible to not decrypt a frame even if a key
 * for it has been uploaded to hardware, the stack will not make any
 * decision based on whether a key has been uploaded or not but rather
 * based on the receive flags.
 *
 * The &struct ieee80211_key_conf structure pointed to by the @key
 * parameter is guaranteed to be valid until another call to set_key()
 * removes it, but it can only be used as a cookie to differentiate
 * keys.
 *
 * In TKIP some HW need to be provided a phase 1 key, for RX decryption
 * acceleration (i.e. iwlwifi). Those drivers should provide update_tkip_key
 * handler.
 * The update_tkip_key() call updates the driver with the new phase 1 key.
 * This happens everytime the iv16 wraps around (every 65536 packets). The
 * set_key() call will happen only once for each key (unless the AP did
 * rekeying), it will not include a valid phase 1 key. The valid phase 1 key is
 * provided by update_tkip_key only. The trigger that makes mac80211 call this
 * handler is software decryption with wrap around of iv16.
 */

/**
 * DOC: Powersave support
 *
 * mac80211 has support for various powersave implementations.
 *
 * First, it can support hardware that handles all powersaving by
 * itself, such hardware should simply set the %IEEE80211_HW_SUPPORTS_PS
 * hardware flag. In that case, it will be told about the desired
 * powersave mode depending on the association status, and the driver
 * must take care of sending nullfunc frames when necessary, i.e. when
 * entering and leaving powersave mode. The driver is required to look at
 * the AID in beacons and signal to the AP that it woke up when it finds
 * traffic directed to it. This mode supports dynamic PS by simply
 * enabling/disabling PS.
 *
 * Additionally, such hardware may set the %IEEE80211_HW_SUPPORTS_DYNAMIC_PS
 * flag to indicate that it can support dynamic PS mode itself (see below).
 *
 * Other hardware designs cannot send nullfunc frames by themselves and also
 * need software support for parsing the TIM bitmap. This is also supported
 * by mac80211 by combining the %IEEE80211_HW_SUPPORTS_PS and
 * %IEEE80211_HW_PS_NULLFUNC_STACK flags. The hardware is of course still
 * required to pass up beacons. The hardware is still required to handle
 * waking up for multicast traffic; if it cannot the driver must handle that
 * as best as it can, mac80211 is too slow.
 *
 * Dynamic powersave mode is an extension to normal powersave mode in which
 * the hardware stays awake for a user-specified period of time after sending
 * a frame so that reply frames need not be buffered and therefore delayed
 * to the next wakeup. This can either be supported by hardware, in which case
 * the driver needs to look at the @dynamic_ps_timeout hardware configuration
 * value, or by the stack if all nullfunc handling is in the stack.
 */

/**
 * DOC: Beacon filter support
 *
 * Some hardware have beacon filter support to reduce host cpu wakeups
 * which will reduce system power consumption. It usuallly works so that
 * the firmware creates a checksum of the beacon but omits all constantly
 * changing elements (TSF, TIM etc). Whenever the checksum changes the
 * beacon is forwarded to the host, otherwise it will be just dropped. That
 * way the host will only receive beacons where some relevant information
 * (for example ERP protection or WMM settings) have changed.
 *
 * Beacon filter support is advertised with the %IEEE80211_HW_BEACON_FILTER
 * hardware capability. The driver needs to enable beacon filter support
 * whenever power save is enabled, that is %IEEE80211_CONF_PS is set. When
 * power save is enabled, the stack will not check for beacon loss and the
 * driver needs to notify about loss of beacons with ieee80211_beacon_loss().
 *
 * The time (or number of beacons missed) until the firmware notifies the
 * driver of a beacon loss event (which in turn causes the driver to call
 * ieee80211_beacon_loss()) should be configurable and will be controlled
 * by mac80211 and the roaming algorithm in the future.
 *
 * Since there may be constantly changing information elements that nothing
 * in the software stack cares about, we will, in the future, have mac80211
 * tell the driver which information elements are interesting in the sense
 * that we want to see changes in them. This will include
 *  - a list of information element IDs
 *  - a list of OUIs for the vendor information element
 *
 * Ideally, the hardware would filter out any beacons without changes in the
 * requested elements, but if it cannot support that it may, at the expense
 * of some efficiency, filter out only a subset. For example, if the device
 * doesn't support checking for OUIs it should pass up all changes in all
 * vendor information elements.
 *
 * Note that change, for the sake of simplification, also includes information
 * elements appearing or disappearing from the beacon.
 *
 * Some hardware supports an "ignore list" instead, just make sure nothing
 * that was requested is on the ignore list, and include commonly changing
 * information element IDs in the ignore list, for example 11 (BSS load) and
 * the various vendor-assigned IEs with unknown contents (128, 129, 133-136,
 * 149, 150, 155, 156, 173, 176, 178, 179, 219); for forward compatibility
 * it could also include some currently unused IDs.
 *
 *
 * In addition to these capabilities, hardware should support notifying the
 * host of changes in the beacon RSSI. This is relevant to implement roaming
 * when no traffic is flowing (when traffic is flowing we see the RSSI of
 * the received data packets). This can consist in notifying the host when
 * the RSSI changes significantly or when it drops below or rises above
 * configurable thresholds. In the future these thresholds will also be
 * configured by mac80211 (which gets them from userspace) to implement
 * them as the roaming algorithm requires.
 *
 * If the hardware cannot implement this, the driver should ask it to
 * periodically pass beacon frames to the host so that software can do the
 * signal strength threshold checking.
 */

/**
 * DOC: Frame filtering
 *
 * mac80211 requires to see many management frames for proper
 * operation, and users may want to see many more frames when
 * in monitor mode. However, for best CPU usage and power consumption,
 * having as few frames as possible percolate through the stack is
 * desirable. Hence, the hardware should filter as much as possible.
 *
 * To achieve this, mac80211 uses filter flags (see below) to tell
 * the driver's configure_filter() function which frames should be
 * passed to mac80211 and which should be filtered out.
 *
 * Before configure_filter() is invoked, the prepare_multicast()
 * callback is invoked with the parameters @mc_count and @mc_list
 * for the combined multicast address list of all virtual interfaces.
 * It's use is optional, and it returns a u64 that is passed to
 * configure_filter(). Additionally, configure_filter() has the
 * arguments @changed_flags telling which flags were changed and
 * @total_flags with the new flag states.
 *
 * If your device has no multicast address filters your driver will
 * need to check both the %FIF_ALLMULTI flag and the @mc_count
 * parameter to see whether multicast frames should be accepted
 * or dropped.
 *
 * All unsupported flags in @total_flags must be cleared.
 * Hardware does not support a flag if it is incapable of _passing_
 * the frame to the stack. Otherwise the driver must ignore
 * the flag, but not clear it.
 * You must _only_ clear the flag (announce no support for the
 * flag to mac80211) if you are not able to pass the packet type
 * to the stack (so the hardware always filters it).
 * So for example, you should clear @FIF_CONTROL, if your hardware
 * always filters control frames. If your hardware always passes
 * control frames to the kernel and is incapable of filtering them,
 * you do _not_ clear the @FIF_CONTROL flag.
 * This rule applies to all other FIF flags as well.
 */

/**
 * enum ieee80211_filter_flags - hardware filter flags
 *
 * These flags determine what the filter in hardware should be
 * programmed to let through and what should not be passed to the
 * stack. It is always safe to pass more frames than requested,
 * but this has negative impact on power consumption.
 *
 * @FIF_PROMISC_IN_BSS: promiscuous mode within your BSS,
 *      think of the BSS as your network segment and then this corresponds
 *      to the regular ethernet device promiscuous mode.
 *
 * @FIF_ALLMULTI: pass all multicast frames, this is used if requested
 *      by the user or if the hardware is not capable of filtering by
 *      multicast address.
 *
 * @FIF_FCSFAIL: pass frames with failed FCS (but you need to set the
 *      %RX_FLAG_FAILED_FCS_CRC for them)
 *
 * @FIF_PLCPFAIL: pass frames with failed PLCP CRC (but you need to set
 *      the %RX_FLAG_FAILED_PLCP_CRC for them
 *
 * @FIF_BCN_PRBRESP_PROMISC: This flag is set during scanning to indicate
 *      to the hardware that it should not filter beacons or probe responses
 *      by BSSID. Filtering them can greatly reduce the amount of processing
 *      mac80211 needs to do and the amount of CPU wakeups, so you should
 *      honour this flag if possible.
 *
 * @FIF_CONTROL: pass control frames (except for PS Poll), if PROMISC_IN_BSS
 *  is not set then only those addressed to this station.
 *
 * @FIF_OTHER_BSS: pass frames destined to other BSSes
 *
 * @FIF_PSPOLL: pass PS Poll frames, if PROMISC_IN_BSS  is not set then only
 *  those addressed to this station.
 */
enum ieee80211_filter_flags {
        FIF_PROMISC_IN_BSS      = 1<<0,
        FIF_ALLMULTI            = 1<<1,
        FIF_FCSFAIL             = 1<<2,
        FIF_PLCPFAIL            = 1<<3,
        FIF_BCN_PRBRESP_PROMISC = 1<<4,
        FIF_CONTROL             = 1<<5,
        FIF_OTHER_BSS           = 1<<6,
        FIF_PSPOLL              = 1<<7,
};

/**
 * enum ieee80211_ampdu_mlme_action - A-MPDU actions
 *
 * These flags are used with the ampdu_action() callback in
 * &struct ieee80211_ops to indicate which action is needed.
 *
 * Note that drivers MUST be able to deal with a TX aggregation
 * session being stopped even before they OK'ed starting it by
 * calling ieee80211_start_tx_ba_cb(_irqsafe), because the peer
 * might receive the addBA frame and send a delBA right away!
 *
 * @IEEE80211_AMPDU_RX_START: start Rx aggregation
 * @IEEE80211_AMPDU_RX_STOP: stop Rx aggregation
 * @IEEE80211_AMPDU_TX_START: start Tx aggregation
 * @IEEE80211_AMPDU_TX_STOP: stop Tx aggregation
 * @IEEE80211_AMPDU_TX_OPERATIONAL: TX aggregation has become operational
 */
enum ieee80211_ampdu_mlme_action {
        IEEE80211_AMPDU_RX_START,
        IEEE80211_AMPDU_RX_STOP,
        IEEE80211_AMPDU_TX_START,
        IEEE80211_AMPDU_TX_STOP,
        IEEE80211_AMPDU_TX_OPERATIONAL,
};

/**
 * struct ieee80211_ops - callbacks from mac80211 to the driver
 *
 * This structure contains various callbacks that the driver may
 * handle or, in some cases, must handle, for example to configure
 * the hardware to a new channel or to transmit a frame.
 *
 * @tx: Handler that 802.11 module calls for each transmitted frame.
 *      skb contains the buffer starting from the IEEE 802.11 header.
 *      The low-level driver should send the frame out based on
 *      configuration in the TX control data. This handler should,
 *      preferably, never fail and stop queues appropriately, more
 *      importantly, however, it must never fail for A-MPDU-queues.
 *      This function should return NETDEV_TX_OK except in very
 *      limited cases.
 *      Must be implemented and atomic.
 *
 * @start: Called before the first netdevice attached to the hardware
 *      is enabled. This should turn on the hardware and must turn on
 *      frame reception (for possibly enabled monitor interfaces.)
 *      Returns negative error codes, these may be seen in userspace,
 *      or zero.
 *      When the device is started it should not have a MAC address
 *      to avoid acknowledging frames before a non-monitor device
 *      is added.
 *      Must be implemented.
 *
 * @stop: Called after last netdevice attached to the hardware
 *      is disabled. This should turn off the hardware (at least
 *      it must turn off frame reception.)
 *      May be called right after add_interface if that rejects
 *      an interface. If you added any work onto the mac80211 workqueue
 *      you should ensure to cancel it on this callback.
 *      Must be implemented.
 *
 * @add_interface: Called when a netdevice attached to the hardware is
 *      enabled. Because it is not called for monitor mode devices, @start
 *      and @stop must be implemented.
 *      The driver should perform any initialization it needs before
 *      the device can be enabled. The initial configuration for the
 *      interface is given in the conf parameter.
 *      The callback may refuse to add an interface by returning a
 *      negative error code (which will be seen in userspace.)
 *      Must be implemented.
 *
 * @remove_interface: Notifies a driver that an interface is going down.
 *      The @stop callback is called after this if it is the last interface
 *      and no monitor interfaces are present.
 *      When all interfaces are removed, the MAC address in the hardware
 *      must be cleared so the device no longer acknowledges packets,
 *      the mac_addr member of the conf structure is, however, set to the
 *      MAC address of the device going away.
 *      Hence, this callback must be implemented.
 *
 * @config: Handler for configuration requests. IEEE 802.11 code calls this
 *      function to change hardware configuration, e.g., channel.
 *      This function should never fail but returns a negative error code
 *      if it does.
 *
 * @bss_info_changed: Handler for configuration requests related to BSS
 *      parameters that may vary during BSS's lifespan, and may affect low
 *      level driver (e.g. assoc/disassoc status, erp parameters).
 *      This function should not be used if no BSS has been set, unless
 *      for association indication. The @changed parameter indicates which
 *      of the bss parameters has changed when a call is made.
 *
 * @prepare_multicast: Prepare for multicast filter configuration.
 *      This callback is optional, and its return value is passed
 *      to configure_filter(). This callback must be atomic.
 *
 * @configure_filter: Configure the device's RX filter.
 *      See the section "Frame filtering" for more information.
 *      This callback must be implemented.
 *
 * @set_tim: Set TIM bit. mac80211 calls this function when a TIM bit
 *      must be set or cleared for a given STA. Must be atomic.
 *
 * @set_key: See the section "Hardware crypto acceleration"
 *      This callback can sleep, and is only called between add_interface
 *      and remove_interface calls, i.e. while the given virtual interface
 *      is enabled.
 *      Returns a negative error code if the key can't be added.
 *
 * @update_tkip_key: See the section "Hardware crypto acceleration"
 *      This callback will be called in the context of Rx. Called for drivers
 *      which set IEEE80211_KEY_FLAG_TKIP_REQ_RX_P1_KEY.
 *
 * @hw_scan: Ask the hardware to service the scan request, no need to start
 *      the scan state machine in stack. The scan must honour the channel
 *      configuration done by the regulatory agent in the wiphy's
 *      registered bands. The hardware (or the driver) needs to make sure
 *      that power save is disabled.
 *      The @req ie/ie_len members are rewritten by mac80211 to contain the
 *      entire IEs after the SSID, so that drivers need not look at these
 *      at all but just send them after the SSID -- mac80211 includes the
 *      (extended) supported rates and HT information (where applicable).
 *      When the scan finishes, ieee80211_scan_completed() must be called;
 *      note that it also must be called when the scan cannot finish due to
 *      any error unless this callback returned a negative error code.
 *
 * @sw_scan_start: Notifier function that is called just before a software scan
 *      is started. Can be NULL, if the driver doesn't need this notification.
 *
 * @sw_scan_complete: Notifier function that is called just after a software scan
 *      finished. Can be NULL, if the driver doesn't need this notification.
 *
 * @get_stats: Return low-level statistics.
 *      Returns zero if statistics are available.
 *
 * @get_tkip_seq: If your device implements TKIP encryption in hardware this
 *      callback should be provided to read the TKIP transmit IVs (both IV32
 *      and IV16) for the given key from hardware.
 *
 * @set_rts_threshold: Configuration of RTS threshold (if device needs it)
 *
 * @sta_notify: Notifies low level driver about addition, removal or power
 *      state transition of an associated station, AP,  IBSS/WDS/mesh peer etc.
 *      Must be atomic.
 *
 * @conf_tx: Configure TX queue parameters (EDCF (aifs, cw_min, cw_max),
 *      bursting) for a hardware TX queue.
 *      Returns a negative error code on failure.
 *
 * @get_tx_stats: Get statistics of the current TX queue status. This is used
 *      to get number of currently queued packets (queue length), maximum queue
 *      size (limit), and total number of packets sent using each TX queue
 *      (count). The 'stats' pointer points to an array that has hw->queues
 *      items.
 *
 * @get_tsf: Get the current TSF timer value from firmware/hardware. Currently,
 *      this is only used for IBSS mode BSSID merging and debugging. Is not a
 *      required function.
 *
 * @set_tsf: Set the TSF timer to the specified value in the firmware/hardware.
 *      Currently, this is only used for IBSS mode debugging. Is not a
 *      required function.
 *
 * @reset_tsf: Reset the TSF timer and allow firmware/hardware to synchronize
 *      with other STAs in the IBSS. This is only used in IBSS mode. This
 *      function is optional if the firmware/hardware takes full care of
 *      TSF synchronization.
 *
 * @tx_last_beacon: Determine whether the last IBSS beacon was sent by us.
 *      This is needed only for IBSS mode and the result of this function is
 *      used to determine whether to reply to Probe Requests.
 *      Returns non-zero if this device sent the last beacon.
 *
 * @ampdu_action: Perform a certain A-MPDU action
 *      The RA/TID combination determines the destination and TID we want
 *      the ampdu action to be performed for. The action is defined through
 *      ieee80211_ampdu_mlme_action. Starting sequence number (@ssn)
 *      is the first frame we expect to perform the action on. Notice
 *      that TX/RX_STOP can pass NULL for this parameter.
 *      Returns a negative error code on failure.
 *
 * @rfkill_poll: Poll rfkill hardware state. If you need this, you also
 *      need to set wiphy->rfkill_poll to %true before registration,
 *      and need to call wiphy_rfkill_set_hw_state() in the callback.
 *
 * @testmode_cmd: Implement a cfg80211 test mode command.
 */
struct ieee80211_ops {
        int (*tx)(struct ieee80211_hw *hw, struct sk_buff *skb);
        int (*start)(struct ieee80211_hw *hw);
        void (*stop)(struct ieee80211_hw *hw);
        int (*add_interface)(struct ieee80211_hw *hw,
                             struct ieee80211_if_init_conf *conf);
        void (*remove_interface)(struct ieee80211_hw *hw,
                                 struct ieee80211_if_init_conf *conf);
        int (*config)(struct ieee80211_hw *hw, u32 changed);
        void (*bss_info_changed)(struct ieee80211_hw *hw,
                                 struct ieee80211_vif *vif,
                                 struct ieee80211_bss_conf *info,
                                 u32 changed);
        u64 (*prepare_multicast)(struct ieee80211_hw *hw,
                                 int mc_count, struct dev_addr_list *mc_list);
        void (*configure_filter)(struct ieee80211_hw *hw,
                                 unsigned int changed_flags,
                                 unsigned int *total_flags,
                                 u64 multicast);
        int (*set_tim)(struct ieee80211_hw *hw, struct ieee80211_sta *sta,
                       bool set);
        int (*set_key)(struct ieee80211_hw *hw, enum set_key_cmd cmd,
                       struct ieee80211_vif *vif, struct ieee80211_sta *sta,
                       struct ieee80211_key_conf *key);
        void (*update_tkip_key)(struct ieee80211_hw *hw,
                        struct ieee80211_key_conf *conf, const u8 *address,
                        u32 iv32, u16 *phase1key);
        int (*hw_scan)(struct ieee80211_hw *hw,
                       struct cfg80211_scan_request *req);
        void (*sw_scan_start)(struct ieee80211_hw *hw);
        void (*sw_scan_complete)(struct ieee80211_hw *hw);
        int (*get_stats)(struct ieee80211_hw *hw,
                         struct ieee80211_low_level_stats *stats);
        void (*get_tkip_seq)(struct ieee80211_hw *hw, u8 hw_key_idx,
                             u32 *iv32, u16 *iv16);
        int (*set_rts_threshold)(struct ieee80211_hw *hw, u32 value);
        void (*sta_notify)(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
                        enum sta_notify_cmd, struct ieee80211_sta *sta);
        int (*conf_tx)(struct ieee80211_hw *hw, u16 queue,
                       const struct ieee80211_tx_queue_params *params);
        int (*get_tx_stats)(struct ieee80211_hw *hw,
                            struct ieee80211_tx_queue_stats *stats);
        u64 (*get_tsf)(struct ieee80211_hw *hw);
        void (*set_tsf)(struct ieee80211_hw *hw, u64 tsf);
        void (*reset_tsf)(struct ieee80211_hw *hw);
        int (*tx_last_beacon)(struct ieee80211_hw *hw);
        int (*ampdu_action)(struct ieee80211_hw *hw,
                            enum ieee80211_ampdu_mlme_action action,
                            struct ieee80211_sta *sta, u16 tid, u16 *ssn);

        void (*rfkill_poll)(struct ieee80211_hw *hw);
#ifdef CONFIG_NL80211_TESTMODE
        int (*testmode_cmd)(struct ieee80211_hw *hw, void *data, int len);
#endif
};

/**
 * ieee80211_alloc_hw -  Allocate a new hardware device
 *
 * This must be called once for each hardware device. The returned pointer
 * must be used to refer to this device when calling other functions.
 * mac80211 allocates a private data area for the driver pointed to by
 * @priv in &struct ieee80211_hw, the size of this area is given as
 * @priv_data_len.
 *
 * @priv_data_len: length of private data
 * @ops: callbacks for this device
 */
struct ieee80211_hw *ieee80211_alloc_hw(size_t priv_data_len,
                                        const struct ieee80211_ops *ops);

/**
 * ieee80211_register_hw - Register hardware device
 *
 * You must call this function before any other functions in
 * mac80211. Note that before a hardware can be registered, you
 * need to fill the contained wiphy's information.
 *
 * @hw: the device to register as returned by ieee80211_alloc_hw()
 */
int ieee80211_register_hw(struct ieee80211_hw *hw);

#ifdef CONFIG_MAC80211_LEDS
extern char *__ieee80211_get_tx_led_name(struct ieee80211_hw *hw);
extern char *__ieee80211_get_rx_led_name(struct ieee80211_hw *hw);
extern char *__ieee80211_get_assoc_led_name(struct ieee80211_hw *hw);
extern char *__ieee80211_get_radio_led_name(struct ieee80211_hw *hw);
#endif
/**
 * ieee80211_get_tx_led_name - get name of TX LED
 *
 * mac80211 creates a transmit LED trigger for each wireless hardware
 * that can be used to drive LEDs if your driver registers a LED device.
 * This function returns the name (or %NULL if not configured for LEDs)
 * of the trigger so you can automatically link the LED device.
 *
 * @hw: the hardware to get the LED trigger name for
 */
static inline char *ieee80211_get_tx_led_name(struct ieee80211_hw *hw)
{
#ifdef CONFIG_MAC80211_LEDS
        return __ieee80211_get_tx_led_name(hw);
#else
        return NULL;
#endif
}

/**
 * ieee80211_get_rx_led_name - get name of RX LED
 *
 * mac80211 creates a receive LED trigger for each wireless hardware
 * that can be used to drive LEDs if your driver registers a LED device.
 * This function returns the name (or %NULL if not configured for LEDs)
 * of the trigger so you can automatically link the LED device.
 *
 * @hw: the hardware to get the LED trigger name for
 */
static inline char *ieee80211_get_rx_led_name(struct ieee80211_hw *hw)
{
#ifdef CONFIG_MAC80211_LEDS
        return __ieee80211_get_rx_led_name(hw);
#else
        return NULL;
#endif
}

/**
 * ieee80211_get_assoc_led_name - get name of association LED
 *
 * mac80211 creates a association LED trigger for each wireless hardware
 * that can be used to drive LEDs if your driver registers a LED device.
 * This function returns the name (or %NULL if not configured for LEDs)
 * of the trigger so you can automatically link the LED device.
 *
 * @hw: the hardware to get the LED trigger name for
 */
static inline char *ieee80211_get_assoc_led_name(struct ieee80211_hw *hw)
{
#ifdef CONFIG_MAC80211_LEDS
        return __ieee80211_get_assoc_led_name(hw);
#else
        return NULL;
#endif
}

/**
 * ieee80211_get_radio_led_name - get name of radio LED
 *
 * mac80211 creates a radio change LED trigger for each wireless hardware
 * that can be used to drive LEDs if your driver registers a LED device.
 * This function returns the name (or %NULL if not configured for LEDs)
 * of the trigger so you can automatically link the LED device.
 *
 * @hw: the hardware to get the LED trigger name for
 */
static inline char *ieee80211_get_radio_led_name(struct ieee80211_hw *hw)
{
#ifdef CONFIG_MAC80211_LEDS
        return __ieee80211_get_radio_led_name(hw);
#else
        return NULL;
#endif
}

/**
 * ieee80211_unregister_hw - Unregister a hardware device
 *
 * This function instructs mac80211 to free allocated resources
 * and unregister netdevices from the networking subsystem.
 *
 * @hw: the hardware to unregister
 */
void ieee80211_unregister_hw(struct ieee80211_hw *hw);

/**
 * ieee80211_free_hw - free hardware descriptor
 *
 * This function frees everything that was allocated, including the
 * private data for the driver. You must call ieee80211_unregister_hw()
 * before calling this function.
 *
 * @hw: the hardware to free
 */
void ieee80211_free_hw(struct ieee80211_hw *hw);

/**
 * ieee80211_restart_hw - restart hardware completely
 *
 * Call this function when the hardware was restarted for some reason
 * (hardware error, ...) and the driver is unable to restore its state
 * by itself. mac80211 assumes that at this point the driver/hardware
 * is completely uninitialised and stopped, it starts the process by
 * calling the ->start() operation. The driver will need to reset all
 * internal state that it has prior to calling this function.
 *
 * @hw: the hardware to restart
 */
void ieee80211_restart_hw(struct ieee80211_hw *hw);

/**
 * ieee80211_rx - receive frame
 *
 * Use this function to hand received frames to mac80211. The receive
 * buffer in @skb must start with an IEEE 802.11 header or a radiotap
 * header if %RX_FLAG_RADIOTAP is set in the @status flags.
 *
 * This function may not be called in IRQ context. Calls to this function
 * for a single hardware must be synchronized against each other. Calls
 * to this function and ieee80211_rx_irqsafe() may not be mixed for a
 * single hardware.
 *
 * Note that right now, this function must be called with softirqs disabled.
 *
 * @hw: the hardware this frame came in on
 * @skb: the buffer to receive, owned by mac80211 after this call
 */
void ieee80211_rx(struct ieee80211_hw *hw, struct sk_buff *skb);

/**
 * ieee80211_rx_irqsafe - receive frame
 *
 * Like ieee80211_rx() but can be called in IRQ context
 * (internally defers to a tasklet.)
 *
 * Calls to this function and ieee80211_rx() may not be mixed for a
 * single hardware.
 *
 * @hw: the hardware this frame came in on
 * @skb: the buffer to receive, owned by mac80211 after this call
 */
void ieee80211_rx_irqsafe(struct ieee80211_hw *hw, struct sk_buff *skb);

/**
 * ieee80211_tx_status - transmit status callback
 *
 * Call this function for all transmitted frames after they have been
 * transmitted. It is permissible to not call this function for
 * multicast frames but this can affect statistics.
 *
 * This function may not be called in IRQ context. Calls to this function
 * for a single hardware must be synchronized against each other. Calls
 * to this function and ieee80211_tx_status_irqsafe() may not be mixed
 * for a single hardware.
 *
 * @hw: the hardware the frame was transmitted by
 * @skb: the frame that was transmitted, owned by mac80211 after this call
 */
void ieee80211_tx_status(struct ieee80211_hw *hw,
                         struct sk_buff *skb);

/**
 * ieee80211_tx_status_irqsafe - IRQ-safe transmit status callback
 *
 * Like ieee80211_tx_status() but can be called in IRQ context
 * (internally defers to a tasklet.)
 *
 * Calls to this function and ieee80211_tx_status() may not be mixed for a
 * single hardware.
 *
 * @hw: the hardware the frame was transmitted by
 * @skb: the frame that was transmitted, owned by mac80211 after this call
 */
void ieee80211_tx_status_irqsafe(struct ieee80211_hw *hw,
                                 struct sk_buff *skb);

/**
 * ieee80211_beacon_get - beacon generation function
 * @hw: pointer obtained from ieee80211_alloc_hw().
 * @vif: &struct ieee80211_vif pointer from &struct ieee80211_if_init_conf.
 *
 * If the beacon frames are generated by the host system (i.e., not in
 * hardware/firmware), the low-level driver uses this function to receive
 * the next beacon frame from the 802.11 code. The low-level is responsible
 * for calling this function before beacon data is needed (e.g., based on
 * hardware interrupt). Returned skb is used only once and low-level driver
 * is responsible for freeing it.
 */
struct sk_buff *ieee80211_beacon_get(struct ieee80211_hw *hw,
                                     struct ieee80211_vif *vif);

/**
 * ieee80211_rts_get - RTS frame generation function
 * @hw: pointer obtained from ieee80211_alloc_hw().
 * @vif: &struct ieee80211_vif pointer from &struct ieee80211_if_init_conf.
 * @frame: pointer to the frame that is going to be protected by the RTS.
 * @frame_len: the frame length (in octets).
 * @frame_txctl: &struct ieee80211_tx_info of the frame.
 * @rts: The buffer where to store the RTS frame.
 *
 * If the RTS frames are generated by the host system (i.e., not in
 * hardware/firmware), the low-level driver uses this function to receive
 * the next RTS frame from the 802.11 code. The low-level is responsible
 * for calling this function before and RTS frame is needed.
 */
void ieee80211_rts_get(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
                       const void *frame, size_t frame_len,
                       const struct ieee80211_tx_info *frame_txctl,
                       struct ieee80211_rts *rts);

/**
 * ieee80211_rts_duration - Get the duration field for an RTS frame
 * @hw: pointer obtained from ieee80211_alloc_hw().
 * @vif: &struct ieee80211_vif pointer from &struct ieee80211_if_init_conf.
 * @frame_len: the length of the frame that is going to be protected by the RTS.
 * @frame_txctl: &struct ieee80211_tx_info of the frame.
 *
 * If the RTS is generated in firmware, but the host system must provide
 * the duration field, the low-level driver uses this function to receive
 * the duration field value in little-endian byteorder.
 */
__le16 ieee80211_rts_duration(struct ieee80211_hw *hw,
                              struct ieee80211_vif *vif, size_t frame_len,
                              const struct ieee80211_tx_info *frame_txctl);

/**
 * ieee80211_ctstoself_get - CTS-to-self frame generation function
 * @hw: pointer obtained from ieee80211_alloc_hw().
 * @vif: &struct ieee80211_vif pointer from &struct ieee80211_if_init_conf.
 * @frame: pointer to the frame that is going to be protected by the CTS-to-self.
 * @frame_len: the frame length (in octets).
 * @frame_txctl: &struct ieee80211_tx_info of the frame.
 * @cts: The buffer where to store the CTS-to-self frame.
 *
 * If the CTS-to-self frames are generated by the host system (i.e., not in
 * hardware/firmware), the low-level driver uses this function to receive
 * the next CTS-to-self frame from the 802.11 code. The low-level is responsible
 * for calling this function before and CTS-to-self frame is needed.
 */
void ieee80211_ctstoself_get(struct ieee80211_hw *hw,
                             struct ieee80211_vif *vif,
                             const void *frame, size_t frame_len,
                             const struct ieee80211_tx_info *frame_txctl,
                             struct ieee80211_cts *cts);

/**
 * ieee80211_ctstoself_duration - Get the duration field for a CTS-to-self frame
 * @hw: pointer obtained from ieee80211_alloc_hw().
 * @vif: &struct ieee80211_vif pointer from &struct ieee80211_if_init_conf.
 * @frame_len: the length of the frame that is going to be protected by the CTS-to-self.
 * @frame_txctl: &struct ieee80211_tx_info of the frame.
 *
 * If the CTS-to-self is generated in firmware, but the host system must provide
 * the duration field, the low-level driver uses this function to receive
 * the duration field value in little-endian byteorder.
 */
__le16 ieee80211_ctstoself_duration(struct ieee80211_hw *hw,
                                    struct ieee80211_vif *vif,
                                    size_t frame_len,
                                    const struct ieee80211_tx_info *frame_txctl);

/**
 * ieee80211_generic_frame_duration - Calculate the duration field for a frame
 * @hw: pointer obtained from ieee80211_alloc_hw().
 * @vif: &struct ieee80211_vif pointer from &struct ieee80211_if_init_conf.
 * @frame_len: the length of the frame.
 * @rate: the rate at which the frame is going to be transmitted.
 *
 * Calculate the duration field of some generic frame, given its
 * length and transmission rate (in 100kbps).
 */
__le16 ieee80211_generic_frame_duration(struct ieee80211_hw *hw,
                                        struct ieee80211_vif *vif,
                                        size_t frame_len,
                                        struct ieee80211_rate *rate);

/**
 * ieee80211_get_buffered_bc - accessing buffered broadcast and multicast frames
 * @hw: pointer as obtained from ieee80211_alloc_hw().
 * @vif: &struct ieee80211_vif pointer from &struct ieee80211_if_init_conf.
 *
 * Function for accessing buffered broadcast and multicast frames. If
 * hardware/firmware does not implement buffering of broadcast/multicast
 * frames when power saving is used, 802.11 code buffers them in the host
 * memory. The low-level driver uses this function to fetch next buffered
 * frame. In most cases, this is used when generating beacon frame. This
 * function returns a pointer to the next buffered skb or NULL if no more
 * buffered frames are available.
 *
 * Note: buffered frames are returned only after DTIM beacon frame was
 * generated with ieee80211_beacon_get() and the low-level driver must thus
 * call ieee80211_beacon_get() first. ieee80211_get_buffered_bc() returns
 * NULL if the previous generated beacon was not DTIM, so the low-level driver
 * does not need to check for DTIM beacons separately and should be able to
 * use common code for all beacons.
 */
struct sk_buff *
ieee80211_get_buffered_bc(struct ieee80211_hw *hw, struct ieee80211_vif *vif);

/**
 * ieee80211_get_tkip_key - get a TKIP rc4 for skb
 *
 * This function computes a TKIP rc4 key for an skb. It computes
 * a phase 1 key if needed (iv16 wraps around). This function is to
 * be used by drivers which can do HW encryption but need to compute
 * to phase 1/2 key in SW.
 *
 * @keyconf: the parameter passed with the set key
 * @skb: the skb for which the key is needed
 * @type: TBD
 * @key: a buffer to which the key will be written
 */
void ieee80211_get_tkip_key(struct ieee80211_key_conf *keyconf,
                                struct sk_buff *skb,
                                enum ieee80211_tkip_key_type type, u8 *key);
/**
 * ieee80211_wake_queue - wake specific queue
 * @hw: pointer as obtained from ieee80211_alloc_hw().
 * @queue: queue number (counted from zero).
 *
 * Drivers should use this function instead of netif_wake_queue.
 */
void ieee80211_wake_queue(struct ieee80211_hw *hw, int queue);

/**
 * ieee80211_stop_queue - stop specific queue
 * @hw: pointer as obtained from ieee80211_alloc_hw().
 * @queue: queue number (counted from zero).
 *
 * Drivers should use this function instead of netif_stop_queue.
 */
void ieee80211_stop_queue(struct ieee80211_hw *hw, int queue);

/**
 * ieee80211_queue_stopped - test status of the queue
 * @hw: pointer as obtained from ieee80211_alloc_hw().
 * @queue: queue number (counted from zero).
 *
 * Drivers should use this function instead of netif_stop_queue.
 */

int ieee80211_queue_stopped(struct ieee80211_hw *hw, int queue);

/**
 * ieee80211_stop_queues - stop all queues
 * @hw: pointer as obtained from ieee80211_alloc_hw().
 *
 * Drivers should use this function instead of netif_stop_queue.
 */
void ieee80211_stop_queues(struct ieee80211_hw *hw);

/**
 * ieee80211_wake_queues - wake all queues
 * @hw: pointer as obtained from ieee80211_alloc_hw().
 *
 * Drivers should use this function instead of netif_wake_queue.
 */
void ieee80211_wake_queues(struct ieee80211_hw *hw);

/**
 * ieee80211_scan_completed - completed hardware scan
 *
 * When hardware scan offload is used (i.e. the hw_scan() callback is
 * assigned) this function needs to be called by the driver to notify
 * mac80211 that the scan finished.
 *
 * @hw: the hardware that finished the scan
 * @aborted: set to true if scan was aborted
 */
void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted);

/**
 * ieee80211_iterate_active_interfaces - iterate active interfaces
 *
 * This function iterates over the interfaces associated with a given
 * hardware that are currently active and calls the callback for them.
 * This function allows the iterator function to sleep, when the iterator
 * function is atomic @ieee80211_iterate_active_interfaces_atomic can
 * be used.
 *
 * @hw: the hardware struct of which the interfaces should be iterated over
 * @iterator: the iterator function to call
 * @data: first argument of the iterator function
 */
void ieee80211_iterate_active_interfaces(struct ieee80211_hw *hw,
                                         void (*iterator)(void *data, u8 *mac,
                                                struct ieee80211_vif *vif),
                                         void *data);

/**
 * ieee80211_iterate_active_interfaces_atomic - iterate active interfaces
 *
 * This function iterates over the interfaces associated with a given
 * hardware that are currently active and calls the callback for them.
 * This function requires the iterator callback function to be atomic,
 * if that is not desired, use @ieee80211_iterate_active_interfaces instead.
 *
 * @hw: the hardware struct of which the interfaces should be iterated over
 * @iterator: the iterator function to call, cannot sleep
 * @data: first argument of the iterator function
 */
void ieee80211_iterate_active_interfaces_atomic(struct ieee80211_hw *hw,
                                                void (*iterator)(void *data,
                                                    u8 *mac,
                                                    struct ieee80211_vif *vif),
                                                void *data);

/**
 * ieee80211_queue_work - add work onto the mac80211 workqueue
 *
 * Drivers and mac80211 use this to add work onto the mac80211 workqueue.
 * This helper ensures drivers are not queueing work when they should not be.
 *
 * @hw: the hardware struct for the interface we are adding work for
 * @work: the work we want to add onto the mac80211 workqueue
 */
void ieee80211_queue_work(struct ieee80211_hw *hw, struct work_struct *work);

/**
 * ieee80211_queue_delayed_work - add work onto the mac80211 workqueue
 *
 * Drivers and mac80211 use this to queue delayed work onto the mac80211
 * workqueue.
 *
 * @hw: the hardware struct for the interface we are adding work for
 * @dwork: delayable work to queue onto the mac80211 workqueue
 * @delay: number of jiffies to wait before queueing
 */
void ieee80211_queue_delayed_work(struct ieee80211_hw *hw,
                                  struct delayed_work *dwork,
                                  unsigned long delay);

/**
 * ieee80211_start_tx_ba_session - Start a tx Block Ack session.
 * @hw: pointer as obtained from ieee80211_alloc_hw().
 * @ra: receiver address of the BA session recipient
 * @tid: the TID to BA on.
 *
 * Return: success if addBA request was sent, failure otherwise
 *
 * Although mac80211/low level driver/user space application can estimate
 * the need to start aggregation on a certain RA/TID, the session level
 * will be managed by the mac80211.
 */
int ieee80211_start_tx_ba_session(struct ieee80211_hw *hw, u8 *ra, u16 tid);

/**
 * ieee80211_start_tx_ba_cb - low level driver ready to aggregate.
 * @hw: pointer as obtained from ieee80211_alloc_hw().
 * @ra: receiver address of the BA session recipient.
 * @tid: the TID to BA on.
 *
 * This function must be called by low level driver once it has
 * finished with preparations for the BA session.
 */
void ieee80211_start_tx_ba_cb(struct ieee80211_hw *hw, u8 *ra, u16 tid);

/**
 * ieee80211_start_tx_ba_cb_irqsafe - low level driver ready to aggregate.
 * @hw: pointer as obtained from ieee80211_alloc_hw().
 * @ra: receiver address of the BA session recipient.
 * @tid: the TID to BA on.
 *
 * This function must be called by low level driver once it has
 * finished with preparations for the BA session.
 * This version of the function is IRQ-safe.
 */
void ieee80211_start_tx_ba_cb_irqsafe(struct ieee80211_hw *hw, const u8 *ra,
                                      u16 tid);

/**
 * ieee80211_stop_tx_ba_session - Stop a Block Ack session.
 * @hw: pointer as obtained from ieee80211_alloc_hw().
 * @ra: receiver address of the BA session recipient
 * @tid: the TID to stop BA.
 * @initiator: if indicates initiator DELBA frame will be sent.
 *
 * Return: error if no sta with matching da found, success otherwise
 *
 * Although mac80211/low level driver/user space application can estimate
 * the need to stop aggregation on a certain RA/TID, the session level
 * will be managed by the mac80211.
 */
int ieee80211_stop_tx_ba_session(struct ieee80211_hw *hw,
                                 u8 *ra, u16 tid,
                                 enum ieee80211_back_parties initiator);

/**
 * ieee80211_stop_tx_ba_cb - low level driver ready to stop aggregate.
 * @hw: pointer as obtained from ieee80211_alloc_hw().
 * @ra: receiver address of the BA session recipient.
 * @tid: the desired TID to BA on.
 *
 * This function must be called by low level driver once it has
 * finished with preparations for the BA session tear down.
 */
void ieee80211_stop_tx_ba_cb(struct ieee80211_hw *hw, u8 *ra, u8 tid);

/**
 * ieee80211_stop_tx_ba_cb_irqsafe - low level driver ready to stop aggregate.
 * @hw: pointer as obtained from ieee80211_alloc_hw().
 * @ra: receiver address of the BA session recipient.
 * @tid: the desired TID to BA on.
 *
 * This function must be called by low level driver once it has
 * finished with preparations for the BA session tear down.
 * This version of the function is IRQ-safe.
 */
void ieee80211_stop_tx_ba_cb_irqsafe(struct ieee80211_hw *hw, const u8 *ra,
                                     u16 tid);

/**
 * ieee80211_find_sta - find a station
 *
 * @hw: pointer as obtained from ieee80211_alloc_hw()
 * @addr: station's address
 *
 * This function must be called under RCU lock and the
 * resulting pointer is only valid under RCU lock as well.
 */
struct ieee80211_sta *ieee80211_find_sta(struct ieee80211_hw *hw,
                                         const u8 *addr);

/**
 * ieee80211_beacon_loss - inform hardware does not receive beacons
 *
 * @vif: &struct ieee80211_vif pointer from &struct ieee80211_if_init_conf.
 *
 * When beacon filtering is enabled with IEEE80211_HW_BEACON_FILTERING and
 * IEEE80211_CONF_PS is set, the driver needs to inform whenever the
 * hardware is not receiving beacons with this function.
 */
void ieee80211_beacon_loss(struct ieee80211_vif *vif);

/* Rate control API */

/**
 * enum rate_control_changed - flags to indicate which parameter changed
 *
 * @IEEE80211_RC_HT_CHANGED: The HT parameters of the operating channel have
 *      changed, rate control algorithm can update its internal state if needed.
 */
enum rate_control_changed {
        IEEE80211_RC_HT_CHANGED = BIT(0)
};

/**
 * struct ieee80211_tx_rate_control - rate control information for/from RC algo
 *
 * @hw: The hardware the algorithm is invoked for.
 * @sband: The band this frame is being transmitted on.
 * @bss_conf: the current BSS configuration
 * @reported_rate: The rate control algorithm can fill this in to indicate
 *      which rate should be reported to userspace as the current rate and
 *      used for rate calculations in the mesh network.
 * @rts: whether RTS will be used for this frame because it is longer than the
 *      RTS threshold
 * @short_preamble: whether mac80211 will request short-preamble transmission
 *      if the selected rate supports it
 * @max_rate_idx: user-requested maximum rate (not MCS for now)
 * @skb: the skb that will be transmitted, the control information in it needs
 *      to be filled in
 */
struct ieee80211_tx_rate_control {
        struct ieee80211_hw *hw;
        struct ieee80211_supported_band *sband;
        struct ieee80211_bss_conf *bss_conf;
        struct sk_buff *skb;
        struct ieee80211_tx_rate reported_rate;
        bool rts, short_preamble;
        u8 max_rate_idx;
};

struct rate_control_ops {
        struct module *module;
        const char *name;
        void *(*alloc)(struct ieee80211_hw *hw, struct dentry *debugfsdir);
        void (*free)(void *priv);

        void *(*alloc_sta)(void *priv, struct ieee80211_sta *sta, gfp_t gfp);
        void (*rate_init)(void *priv, struct ieee80211_supported_band *sband,
                          struct ieee80211_sta *sta, void *priv_sta);
        void (*rate_update)(void *priv, struct ieee80211_supported_band *sband,
                            struct ieee80211_sta *sta,
                            void *priv_sta, u32 changed);
        void (*free_sta)(void *priv, struct ieee80211_sta *sta,
                         void *priv_sta);

        void (*tx_status)(void *priv, struct ieee80211_supported_band *sband,
                          struct ieee80211_sta *sta, void *priv_sta,
                          struct sk_buff *skb);
        void (*get_rate)(void *priv, struct ieee80211_sta *sta, void *priv_sta,
                         struct ieee80211_tx_rate_control *txrc);

        void (*add_sta_debugfs)(void *priv, void *priv_sta,
                                struct dentry *dir);
        void (*remove_sta_debugfs)(void *priv, void *priv_sta);
};

static inline int rate_supported(struct ieee80211_sta *sta,
                                 enum ieee80211_band band,
                                 int index)
{
        return (sta == NULL || sta->supp_rates[band] & BIT(index));
}

/**
 * rate_control_send_low - helper for drivers for management/no-ack frames
 *
 * Rate control algorithms that agree to use the lowest rate to
 * send management frames and NO_ACK data with the respective hw
 * retries should use this in the beginning of their mac80211 get_rate
 * callback. If true is returned the rate control can simply return.
 * If false is returned we guarantee that sta and sta and priv_sta is
 * not null.
 *
 * Rate control algorithms wishing to do more intelligent selection of
 * rate for multicast/broadcast frames may choose to not use this.
 *
 * @sta: &struct ieee80211_sta pointer to the target destination. Note
 *      that this may be null.
 * @priv_sta: private rate control structure. This may be null.
 * @txrc: rate control information we sholud populate for mac80211.
 */
bool rate_control_send_low(struct ieee80211_sta *sta,
                           void *priv_sta,
                           struct ieee80211_tx_rate_control *txrc);


static inline s8
rate_lowest_index(struct ieee80211_supported_band *sband,
                  struct ieee80211_sta *sta)
{
        int i;

        for (i = 0; i < sband->n_bitrates; i++)
                if (rate_supported(sta, sband->band, i))
                        return i;

        /* warn when we cannot find a rate. */
        WARN_ON(1);

        return 0;
}

static inline
bool rate_usable_index_exists(struct ieee80211_supported_band *sband,
                              struct ieee80211_sta *sta)
{
        unsigned int i;

        for (i = 0; i < sband->n_bitrates; i++)
                if (rate_supported(sta, sband->band, i))
                        return true;
        return false;
}

int ieee80211_rate_control_register(struct rate_control_ops *ops);
void ieee80211_rate_control_unregister(struct rate_control_ops *ops);

static inline bool
conf_is_ht20(struct ieee80211_conf *conf)
{
        return conf->channel_type == NL80211_CHAN_HT20;
}

static inline bool
conf_is_ht40_minus(struct ieee80211_conf *conf)
{
        return conf->channel_type == NL80211_CHAN_HT40MINUS;
}

static inline bool
conf_is_ht40_plus(struct ieee80211_conf *conf)
{
        return conf->channel_type == NL80211_CHAN_HT40PLUS;
}

static inline bool
conf_is_ht40(struct ieee80211_conf *conf)
{
        return conf_is_ht40_minus(conf) || conf_is_ht40_plus(conf);
}

static inline bool
conf_is_ht(struct ieee80211_conf *conf)
{
        return conf->channel_type != NL80211_CHAN_NO_HT;
}

#endif /* MAC80211_H */