September 12, 2006 IEEE80211 9

### NAME

ieee80211_ifattach,ieee80211_ifdetach, ieee80211_mhz2ieee,ieee80211_chan2ieee, ieee80211_ieee2mhz, ieee80211_media_init,ieee80211_media_change, ieee80211_media_status, ieee80211_watchdog, ieee80211_setmode,ieee80211_chan2mode, ieee80211_rate2media,ieee80211_media2rate - core 802.11 network stack functions

### SYNOPSIS

```void` ieee80211_ifattach(```struct ieee80211com *ic`)
```void` ieee80211_ifdetach(```struct ieee80211com *ic`)
```u_int` ieee80211_mhz2ieee(```u_int freq``, u_int flags`)
```u_int` ieee80211_chan2ieee(```struct ieee80211com *ic``, struct ieee80211_channel *c`)
```u_int` ieee80211_ieee2mhz(```u_int chan``, u_int flags`)
```void` ieee80211_media_init(`` ```struct ieee80211com *ic` `ifm_change_cb_t media_change` ```ifm_stat_cb_t media_stat` )
```int` ieee80211_media_change(```struct ifnet *ifp`)
```void` ieee80211_media_status(```struct ifnet *ifp``, struct ifmediareq *imr`)
```void` ieee80211_watchdog(```struct ieee80211com *ic`)
```int` ieee80211_setmode(```struct ieee80211com *ic``, enum ieee80211_phymode mode`)
```enum` `ieee80211_phymode` ieee80211_chan2mode(`` ```struct ieee80211com *ic` `struct ieee80211_channel *chan` )
```int` ieee80211_rate2media(`` ```struct ieee80211com *ic` `int rate` `enum ieee80211_phymode mode` )
```int` ieee80211_media2rate(```int mword`)

### DESCRIPTION

The ieee80211 collection of functions are used to manage wireless network interfaces in the system which use the system's software 802.11 network stack. Most of these functions require that attachment to the stack is performed before calling. Several utility functions are also provided; these are safe to call from any driver without prior initialization.

The ieee80211_ifattach(``) function attaches the wireless network interface ```ic` to the 802.11 network stack layer. This function must be called before using any of the ieee80211 functions which need to store driver state across invocations. This function also performs Ethernet and BPF attachment (by calling ether_ifattach(``) and bpfattach2(``)) on behalf of the caller.

The ieee80211_ifdetach(``) function frees any ieee80211 structures associated with the driver, and performs Ethernet and BPF detachment on behalf of the caller.

The ieee80211_mhz2ieee(``) utility function converts the frequency ```freq` (specified in MHz) to an IEEE 802.11 channel number. The ```flags` argument is a hint which specifies whether the frequency is in the 2GHz ISM band (Vt IEEE80211_CHAN_2GHZ) or the 5GHz band (Vt IEEE80211_CHAN_5GHZ); appropriate clipping of the result is then performed.

The ieee80211_chan2ieee(``) function converts the channel specified in ```*c` to an IEEE channel number for the driver ```ic`. If the conversion would be invalid, an error message is printed to the system console. This function REQUIRES that the driver is hooked up to the ieee80211 subsystem.

The ieee80211_ieee2mhz(``) utility function converts the IEEE channel number
```chan` to a frequency (in MHz). The ```flags` argument is a hint which specifies whether the frequency is in the 2GHz ISM band (Vt IEEE80211_CHAN_2GHZ) or the 5GHz band (Vt IEEE80211_CHAN_5GHZ); appropriate clipping of the result is then performed.

The ieee80211_media_init(``) function initializes media data structures used by the interface for the driver ```ic`. It must be called by the driver after calling ieee80211_ifattach(``) and before calling most ieee80211 functions. The ```media_change` and ```media_stat` arguments specify helper functions which will be invoked by the framework when the user changes or queries media options, using a command such as ifconfig(8).

The ieee80211_media_status(``) and ieee80211_media_change(``) functions are device-independent handlers for commands and are not intended to be called directly.

The ieee80211_watchdog(``) function is intended to be called from a driver's if_watchdog routine. It is used to perform periodic cleanup of state within the software 802.11 stack, as well as timing out scans.

The ieee80211_setmode(``) function is called from within the 802.11 stack to change the mode of the driver's PHY; it is not intended to be called directly.

The ieee80211_chan2mode(``) function returns the PHY mode required for use with the channel ```chan` on the device ```ic`. This is typically used when selecting a rate set, to be advertised in beacons, for example.

The ieee80211_rate2media(``) function converts the bit rate ```rate` (measured in units of 0.5Mbps) to an sub-type, for the device ```ic` running in PHY mode ```mode`. The ieee80211_media2rate(``) performs the reverse of this conversion, returning the bit rate (in 0.5Mbps units) corresponding to an sub-type.

### SEE ALSO

ieee80211_crypto(9), ieee80211_input(9), ieee80211_ioctl(9), ieee80211_node(9), ieee80211_output(9), ieee80211_proto(9), ieee80211_radiotap(9)

### HISTORY

The ieee80211 series of functions first appeared in NetBSD1.5, and were later ported to FreeBSD4.6.

### AUTHORS

This man page was written by Bruce M. Simpson <bms@FreeBSD.org> and Darron Broad <darron@kewl.org>.