Section: The basic mac80211 driver inte (9)
Updated: February 2011
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struct_ieee80211_ops - callbacks from mac80211 to the driver  


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_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);
  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);
  int (* hw_scan) (struct ieee80211_hw *hw, struct ieee80211_vif *vif,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);
  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, u16 queue,const struct ieee80211_tx_queue_params *params);
  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,struct ieee80211_vif *vif,enum ieee80211_ampdu_mlme_action action,struct ieee80211_sta *sta, u16 tid, u16 *ssn);
  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);
  int (* testmode_cmd) (struct ieee80211_hw *hw, void *data, int len);
  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);



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.


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.


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.


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.


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.


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.


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.


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.


Prepare for multicast filter configuration. This callback is optional, and its return value is passed to configure_filter. This callback must be atomic.


Configure the device's RX filter. See the section lqFrame filteringrq for more information. This callback must be implemented and can sleep.


Set TIM bit. mac80211 calls this function when a TIM bit must be set or cleared for a given STA. Must be atomic.


See the section lqHardware crypto accelerationrq 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.


See the section lqHardware crypto accelerationrq 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.


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.


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.


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.


Return low-level statistics. Returns zero if statistics are available. The callback can sleep.


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.


Configuration of RTS threshold (if device needs it) The callback can sleep.


Notifies low level driver about addition of an associated station, AP, IBSS/WDS/mesh peer etc. This callback can sleep.


Notifies low level driver about removal of an associated station, AP, IBSS/WDS/mesh peer etc. This callback can sleep.


Notifies low level driver about power state transition of an associated station, AP, IBSS/WDS/mesh peer etc. Must be atomic.


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 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 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 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.


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.


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. The callback can sleep.


Return per-channel survey information


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 slot time for given coverage class as specified in IEEE 802.11-2007 section and modify ACK timeout accordingly. This callback is not required and may sleep.


Implement a cfg80211 test mode command. The callback can sleep.


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.


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.


Poll Rx queue for incoming data frames.


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.  


Johannes Berg <>