Linux ieee80211_opsを読む

Linuxのieee80211_opsを読んでみました。

ieee80211_ops は Linux Kernelのmac80211とSoftMAC driver間のインターフェイスです。

ieee80211_opsにもたくさんのメソッドがありますが、最低限必ず必要そうな関数を調べてみました。

ソースコード

• https://github.com/torvalds/linux/blob/master/include/net/mac80211.h

ieee80211_ops

tx

• skbで指定したframeをcontrolの送信設定を使ってhwで送信する。

 * @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.
 *  Must be atomic.

    void (*tx)(struct ieee80211_hw *hw,
           struct ieee80211_tx_control *control,
           struct sk_buff *skb);

start

• hwの動作を開始する。

 * @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.

    int (*start)(struct ieee80211_hw *hw);

stop

• hwの動作を停止する。

 * @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.

    void (*stop)(struct ieee80211_hw *hw);

add_interface

• hwにインターフェイスvifを追加する。

 * @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.

    int (*add_interface)(struct ieee80211_hw *hw,
                 struct ieee80211_vif *vif);

remove_interface

• hwのインターフェイスvifを削除する。

 * @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.

    void (*remove_interface)(struct ieee80211_hw *hw,
                 struct ieee80211_vif *vif);

config

• hwの設定を変更する。　changedのフラグの情報のみ変更する。 変更の情報はhw内にある。
• channelを変更する場合などに使う。

 * @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.

    int (*config)(struct ieee80211_hw *hw, u32 changed);

bss_info_changed

• hwのインターフェイスvifにBSS設定infoの設定変更をする。

 * @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.

    void (*bss_info_changed)(struct ieee80211_hw *hw,
                 struct ieee80211_vif *vif,
                 struct ieee80211_bss_conf *info,
                 u32 changed);

conf_tx

• hw vifの送信キューの設定をする

 * @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.

    int (*conf_tx)(struct ieee80211_hw *hw,
               struct ieee80211_vif *vif, u16 ac,
               const struct ieee80211_tx_queue_params *params);

configure_filter

• 受信filterの設定をする。

 * @configure_filter: Configure the device's RX filter.
 *  See the section "Frame filtering" for more information.
 *  This callback must be implemented and can sleep.

    void (*configure_filter)(struct ieee80211_hw *hw,
                 unsigned int changed_flags,
                 unsigned int *total_flags,
                 u64 multicast);