There surely are errors and omissions in this list, please help. Also, if you maintain a driver, please look through this list.
set the IEEE80211_HW_2GHZ_SHORT_PREAMBLE_INCAPABLE hw flag if it cannot receive short preamble transmissions
either honour the IEEE80211_TX_RC_USE_RTS_CTS flag or implement the set_rts_threshold call
either honour the IEEE80211_TX_RC_USE_CTS_PROTECT flag or honour bss_conf's use_cts_prot value
honour bss_conf's use_short_slot or set the IEEE80211_HW_2GHZ_SHORT_SLOT_INCAPABLE hw flag
honour bss_conf's basic_rates bitmap to set up the control response frame bitrate (cf. IEEE 802.11-2007 9.6 “Multirate support” paragraph 7)
honour IEEE80211_TX_CTL_NO_ACK unless the hardware does based on the multicast bit
honour IEEE80211_TX_CTL_ASSIGN_SEQ (only if you implement any mode that requires beaconing)
honour IEEE80211_TX_CTL_REQ_TX_STATUS or always report TX status
not change it's operating mode based on IEEE80211_CONF_RADIOTAP
clear/set MAC address filters/control response frame generation based on the interface add/remove callbacks
set up beacon access parameters based on the interface mode (ibss/ap)
use SET_IEEE80211_DEV and SET_IEEE80211_PERM_ADDR
set the wiphy interface modes
… It also should
honour IEEE80211_TX_RC_USE_SHORT_PREAMBLE or honour bss_conf's use_short_preamble
set one of the IEEE80211_HW_SIGNAL_* hw flags, preferably support dBm For QoS/WME, it must
support at least four queues
support configurable access parameters for those queues
not override the sequence numbers on frames that don't have the IEEE80211_TX_CTL_ASSIGN_SEQ flag set
… For AP mode, it must
honour IEEE80211_TX_CTL_SEND_AFTER_DTIM or set IEEE80211_HW_HOST_BROADCAST_PS_BUFFERING and use the ieee80211_get_buffered_bc() function
must honour IEEE80211_TX_RC_USE_SHORT_PREAMBLE or never do short-preamble transmissions
When sending probe response frames, the timestamp must be adjusted by the hardware or firmware. This is important to power saving stations that happen to adjust their TSF from the timestamp in the probe response frame.
implement sequence numbering for frames with the IEEE80211_TX_CTL_ASSIGN_SEQ flag (or ask the hardware to do it for those frames)
react to the set_tim() callback or fetch each beacon from mac80211 For MESH mode, it must
allow beacons to be transmitted for NL80211_IFTYPE_MESH_POINT interfaces. These can be AP or IBSS style beacons.
receive beacons and control frames for NL80211_IFTYPE_MESH_POINT interfaces
set the NL80211_IFTYPE_MESH_POINT bit in the hw→wiphy→interface_modes mask to indicate that MP mode is supported.
support the FIF_OTHER_BSS filter flag For AP/IBSS/MESH modes, it
must support the enable_beacon config to turn on/off beaconing
should support the tx_last_beacon() callback When implementing hardware crypto, it must