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STRUCT IEEE80211_OPS(9) The basic mac80211 driver inte STRUCT IEEE80211_OPS(9)

NAME

struct_ieee80211_ops - callbacks from mac80211 to the driver

SYNOPSIS

struct ieee80211_ops {
  void (* tx) (struct ieee80211_hw *hw, struct sk_buff *skb);
  int (* start) (struct ieee80211_hw *hw);
  void (* stop) (struct ieee80211_hw *hw);
#ifdef CONFIG_PM
  int (* suspend) (struct ieee80211_hw *hw, struct cfg80211_wowlan *wowlan);
  int (* resume) (struct ieee80211_hw *hw);
#endif
  int (* add_interface) (struct ieee80211_hw *hw,struct ieee80211_vif *vif);
  int (* change_interface) (struct ieee80211_hw *hw,struct ieee80211_vif *vif,enum nl80211_iftype new_type, bool p2p);
  void (* remove_interface) (struct ieee80211_hw *hw,struct ieee80211_vif *vif);
  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);
  int (* tx_sync) (struct ieee80211_hw *hw, struct ieee80211_vif *vif,const u8 *bssid, enum ieee80211_tx_sync_type type);
  void (* finish_tx_sync) (struct ieee80211_hw *hw,struct ieee80211_vif *vif,const u8 *bssid,enum ieee80211_tx_sync_type type);
  u64 (* prepare_multicast) (struct ieee80211_hw *hw,struct netdev_hw_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_vif *vif,struct ieee80211_key_conf *conf,struct ieee80211_sta *sta,u32 iv32, u16 *phase1key);
  void (* set_rekey_data) (struct ieee80211_hw *hw,struct ieee80211_vif *vif,struct cfg80211_gtk_rekey_data *data);
  int (* hw_scan) (struct ieee80211_hw *hw, struct ieee80211_vif *vif,struct cfg80211_scan_request *req);
  void (* cancel_hw_scan) (struct ieee80211_hw *hw,struct ieee80211_vif *vif);
  int (* sched_scan_start) (struct ieee80211_hw *hw,struct ieee80211_vif *vif,struct cfg80211_sched_scan_request *req,struct ieee80211_sched_scan_ies *ies);
  void (* sched_scan_stop) (struct ieee80211_hw *hw,struct ieee80211_vif *vif);
  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_frag_threshold) (struct ieee80211_hw *hw, u32 value);
  int (* set_rts_threshold) (struct ieee80211_hw *hw, u32 value);
  int (* sta_add) (struct ieee80211_hw *hw, struct ieee80211_vif *vif,struct ieee80211_sta *sta);
  int (* sta_remove) (struct ieee80211_hw *hw, struct ieee80211_vif *vif,struct ieee80211_sta *sta);
  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,struct ieee80211_vif *vif, u16 queue,const struct ieee80211_tx_queue_params *params);
  u64 (* get_tsf) (struct ieee80211_hw *hw, struct ieee80211_vif *vif);
  void (* set_tsf) (struct ieee80211_hw *hw, struct ieee80211_vif *vif,u64 tsf);
  void (* reset_tsf) (struct ieee80211_hw *hw, struct ieee80211_vif *vif);
  int (* tx_last_beacon) (struct ieee80211_hw *hw);
  int (* ampdu_action) (struct ieee80211_hw *hw,struct ieee80211_vif *vif,enum ieee80211_ampdu_mlme_action action,struct ieee80211_sta *sta, u16 tid, u16 *ssn,u8 buf_size);
  int (* get_survey) (struct ieee80211_hw *hw, int idx,struct survey_info *survey);
  void (* rfkill_poll) (struct ieee80211_hw *hw);
  void (* set_coverage_class) (struct ieee80211_hw *hw, u8 coverage_class);
#ifdef CONFIG_NL80211_TESTMODE
  int (* testmode_cmd) (struct ieee80211_hw *hw, void *data, int len);
  int (* testmode_dump) (struct ieee80211_hw *hw, struct sk_buff *skb,struct netlink_callback *cb,void *data, int len);
#endif
  void (* flush) (struct ieee80211_hw *hw, bool drop);
  void (* channel_switch) (struct ieee80211_hw *hw,struct ieee80211_channel_switch *ch_switch);
  int (* napi_poll) (struct ieee80211_hw *hw, int budget);
  int (* set_antenna) (struct ieee80211_hw *hw, u32 tx_ant, u32 rx_ant);
  int (* get_antenna) (struct ieee80211_hw *hw, u32 *tx_ant, u32 *rx_ant);
  int (* remain_on_channel) (struct ieee80211_hw *hw,struct ieee80211_channel *chan,enum nl80211_channel_type channel_type,int duration);
  int (* cancel_remain_on_channel) (struct ieee80211_hw *hw);
  int (* set_ringparam) (struct ieee80211_hw *hw, u32 tx, u32 rx);
  void (* get_ringparam) (struct ieee80211_hw *hw,u32 *tx, u32 *tx_max, u32 *rx, u32 *rx_max);
  bool (* tx_frames_pending) (struct ieee80211_hw *hw);
  int (* set_bitrate_mask) (struct ieee80211_hw *hw, struct ieee80211_vif *vif,const struct cfg80211_bitrate_mask *mask);
  void (* rssi_callback) (struct ieee80211_hw *hw,enum ieee80211_rssi_event rssi_event);
  void (* allow_buffered_frames) (struct ieee80211_hw *hw,struct ieee80211_sta *sta,u16 tids, int num_frames,enum ieee80211_frame_release_type reason,bool more_data);
  void (* release_buffered_frames) (struct ieee80211_hw *hw,struct ieee80211_sta *sta,u16 tids, int num_frames,enum ieee80211_frame_release_type reason,bool more_data);
};

MEMBERS

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 and can sleep.
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 and can sleep.
suspend
Suspend the device; mac80211 itself will quiesce before and stop transmitting and doing any other configuration, and then ask the device to suspend. This is only invoked when WoWLAN is configured, otherwise the device is deconfigured completely and reconfigured at resume time. The driver may also impose special conditions under which it wants to use the “normal” suspend (deconfigure), say if it only supports WoWLAN when the device is associated. In this case, it must return 1 from this function.
resume
If WoWLAN was configured, this indicates that mac80211 is now resuming its operation, after this the device must be fully functional again. If this returns an error, the only way out is to also unregister the device. If it returns 1, then mac80211 will also go through the regular complete restart on resume.
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 and can sleep.
change_interface
Called when a netdevice changes type. This callback is optional, but only if it is supported can interface types be switched while the interface is UP. The callback may sleep. Note that while an interface is being switched, it will not be found by the interface iteration callbacks.
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. It can sleep.
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. The callback can sleep.
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. The callback can sleep.
tx_sync
Called before a frame is sent to an AP/GO. In the GO case, the driver should sync with the GO's powersaving so the device doesn't transmit the frame while the GO is asleep. In the regular AP case it may be used by drivers for devices implementing other restrictions on talking to APs, e.g. due to regulatory enforcement or just HW restrictions. This function is called for every authentication, association and action frame separately since applications might attempt to auth with multiple APs before chosing one to associate to. If it returns an error, the corresponding authentication, association or frame transmission is aborted and reported as having failed. It is always called after tuning to the correct channel. The callback might be called multiple times before finish_tx_sync (but finish_tx_sync will be called once for each) but in practice this is unlikely to happen. It can also refuse in that case if the driver cannot handle that situation. This callback can sleep.
finish_tx_sync
Called as a counterpart to tx_sync, unless that returned an error. This callback can sleep.
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 and can sleep.
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 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. The callback can sleep.
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. The callback must be atomic.
set_rekey_data
If the device supports GTK rekeying, for example while the host is suspended, it can assign this callback to retrieve the data necessary to do GTK rekeying, this is the KEK, KCK and replay counter. After rekeying was done it should (for example during resume) notify userspace of the new replay counter using ieee80211_gtk_rekey_notify.
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. The callback can sleep.
cancel_hw_scan
Ask the low-level tp cancel the active hw scan. The driver should ask the hardware to cancel the scan (if possible), but the scan will be completed only after the driver will call ieee80211_scan_completed. This callback is needed for wowlan, to prevent enqueueing a new scan_work after the low-level driver was already suspended. The callback can sleep.
sched_scan_start
Ask the hardware to start scanning repeatedly at specific intervals. The driver must call the ieee80211_sched_scan_results function whenever it finds results. This process will continue until sched_scan_stop is called.
sched_scan_stop
Tell the hardware to stop an ongoing scheduled scan.
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. The callback can sleep.
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. The callback can sleep.
get_stats
Return low-level statistics. Returns zero if statistics are available. The callback can sleep.
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. The callback must be atomic.
set_frag_threshold
Configuration of fragmentation threshold. Assign this if the device does fragmentation by itself; if this callback is implemented then the stack will not do fragmentation. The callback can sleep.
set_rts_threshold
Configuration of RTS threshold (if device needs it) The callback can sleep.
sta_add
Notifies low level driver about addition of an associated station, AP, IBSS/WDS/mesh peer etc. This callback can sleep.
sta_remove
Notifies low level driver about removal of an associated station, AP, IBSS/WDS/mesh peer etc. This callback can sleep.
sta_notify
Notifies low level driver about power state transition of an associated station, AP, IBSS/WDS/mesh peer etc. For a VIF operating in AP mode, this callback will not be called when the flag IEEE80211_HW_AP_LINK_PS is set. 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. The callback can sleep.
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. The callback can sleep.
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. The callback can sleep.
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. The callback can sleep.
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. The callback can sleep.
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. The buf_size parameter is only valid when the action is set to IEEE80211_AMPDU_TX_OPERATIONAL and indicates the peer's reorder buffer size (number of subframes) for this session -- the driver may neither send aggregates containing more subframes than this nor send aggregates in a way that lost frames would exceed the buffer size. If just limiting the aggregate size, this would be
get_survey
Return per-channel survey information
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. The callback can sleep.
set_coverage_class
Set slot time for given coverage class as specified in IEEE 802.11-2007 section 17.3.8.6 and modify ACK timeout accordingly. This callback is not required and may sleep.
testmode_cmd
Implement a cfg80211 test mode command. The callback can sleep.
testmode_dump
Implement a cfg80211 test mode dump. The callback can sleep.
flush
Flush all pending frames from the hardware queue, making sure that the hardware queues are empty. If the parameter drop is set to true, pending frames may be dropped. The callback can sleep.
channel_switch
Drivers that need (or want) to offload the channel switch operation for CSAs received from the AP may implement this callback. They must then call ieee80211_chswitch_done to indicate completion of the channel switch.
napi_poll
Poll Rx queue for incoming data frames.
set_antenna
Set antenna configuration (tx_ant, rx_ant) on the device. Parameters are bitmaps of allowed antennas to use for TX/RX. Drivers may reject TX/RX mask combinations they cannot support by returning -EINVAL (also see nl80211.h NL80211_ATTR_WIPHY_ANTENNA_TX).
get_antenna
Get current antenna configuration from device (tx_ant, rx_ant).
remain_on_channel
Starts an off-channel period on the given channel, must call back to ieee80211_ready_on_channel when on that channel. Note that normal channel traffic is not stopped as this is intended for hw offload. Frames to transmit on the off-channel channel are transmitted normally except for the IEEE80211_TX_CTL_TX_OFFCHAN flag. When the duration (which will always be non-zero) expires, the driver must call ieee80211_remain_on_channel_expired. This callback may sleep.
cancel_remain_on_channel
Requests that an ongoing off-channel period is aborted before it expires. This callback may sleep.
set_ringparam
Set tx and rx ring sizes.
get_ringparam
Get tx and rx ring current and maximum sizes.
tx_frames_pending
Check if there is any pending frame in the hardware queues before entering power save.
set_bitrate_mask
Set a mask of rates to be used for rate control selection when transmitting a frame. Currently only legacy rates are handled. The callback can sleep.
rssi_callback
Notify driver when the average RSSI goes above/below thresholds that were registered previously. The callback can sleep.
allow_buffered_frames
Prepare device to allow the given number of frames to go out to the given station. The frames will be sent by mac80211 via the usual TX path after this call. The TX information for frames released will also have the IEEE80211_TX_CTL_POLL_RESPONSE flag set and the last one will also have IEEE80211_TX_STATUS_EOSP set. In case frames from multiple TIDs are released and the driver might reorder them between the TIDs, it must set the IEEE80211_TX_STATUS_EOSP flag on the last frame and clear it on all others and also handle the EOSP bit in the QoS header correctly. Alternatively, it can also call the ieee80211_sta_eosp_irqsafe function. The tids parameter is a bitmap and tells the driver which TIDs the frames will be on; it will at most have two bits set. This callback must be atomic.
release_buffered_frames
Release buffered frames according to the given parameters. In the case where the driver buffers some frames for sleeping stations mac80211 will use this callback to tell the driver to release some frames, either for PS-poll or uAPSD. Note that if the more_data paramter is false the driver must check if there are more frames on the given TIDs, and if there are more than the frames being released then it must still set the more-data bit in the frame. If the more_data parameter is true, then of course the more-data bit must always be set. The tids parameter tells the driver which TIDs to release frames from, for PS-poll it will always have only a single bit set. In the case this is used for a PS-poll initiated release, the num_frames parameter will always be 1 so code can be shared. In this case the driver must also set IEEE80211_TX_STATUS_EOSP flag on the TX status (and must report TX status) so that the PS-poll period is properly ended. This is used to avoid sending multiple responses for a retried PS-poll frame. In the case this is used for uAPSD, the num_frames parameter may be bigger than one, but the driver may send fewer frames (it must send at least one, however). In this case it is also responsible for setting the EOSP flag in the QoS header of the frames. Also, when the service period ends, the driver must set IEEE80211_TX_STATUS_EOSP on the last frame in the SP. Alternatively, it may call the function ieee80211_sta_eosp_irqsafe to inform mac80211 of the end of the SP. This callback must be atomic.

DESCRIPTION

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.

POSSIBLE WITH A BUF_SIZE OF 8

- TX: 1.....7 - RX: 2....7 (lost frame #1) - TX: 8..1... which is invalid since #1 was now re-transmitted well past the buffer size of 8. Correct ways to retransmit #1 would be: - TX: 1 or 18 or 81 Even “189” would be wrong since 1 could be lost again.
Returns a negative error code on failure. The callback can sleep.

AUTHOR

Johannes Berg <johannes@sipsolutions.net>
Author.

COPYRIGHT

March 2016 Kernel Hackers Manual 3.2.