1.\" 2.\" Copyright (c) 2004 Bruce M. Simpson <bms@spc.org> 3.\" Copyright (c) 2004 Darron Broad <darron@kewl.org> 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 15.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25.\" SUCH DAMAGE. 26.\" 27.\" $FreeBSD: src/share/man/man9/ieee80211_input.9,v 1.5 2009/09/18 00:33:47 brueffer Exp $ 28.\" 29.Dd April 28, 2010 30.Dt IEEE80211_INPUT 9 31.Os 32.Sh NAME 33.Nm ieee80211_input 34.Nd software 802.11 stack input functions 35.Sh SYNOPSIS 36.In netproto/802_11/ieee80211_var.h 37.Ft void 38.Fo ieee80211_input 39.Fa "struct ieee80211_node *" 40.Fa "struct mbuf *" 41.Fa "int rssi" 42.Fa "int noise" 43.Fc 44.Ft void 45.Fo ieee80211_input_all 46.Fa "struct ieee80211com *" 47.Fa "struct mbuf *" 48.Fa "int rssi" 49.Fa "int noise" 50.Fc 51.Sh DESCRIPTION 52The 53.Nm net80211 54layer that supports 802.11 device drivers requires that 55receive processing be single-threaded. 56Typically this is done using a dedicated driver 57.Xr taskqueue 9 58thread. 59.Fn ieee80211_input 60and 61.Fn ieee80211_input_all 62process received 802.11 frames and are designed 63for use in that context; e.g. no driver locks may be held. 64.Pp 65The frame passed up in the 66.Vt mbuf 67must have the 802.11 protocol header at the front; all device-specific 68information and/or PLCP must be removed. 69Any CRC must be stripped from the end of the frame. 70The 802.11 protocol header should be 32-bit aligned for 71optimal performance but receive processing does not require it. 72If the frame holds a payload and that is not aligned to a 32-bit 73boundary then the payload will be re-aligned so that it is suitable 74for processing by protocols such as 75.Xr ip 4 . 76.Pp 77If a device (such as 78.Xr ath 4 ) 79inserts padding after the 802.11 header to align 80the payload to a 32-bit boundary the 81.Dv IEEE80211_C_DATAPAD 82capability must be set. 83Otherwise header and payload are assumed contiguous in the mbuf chain. 84.Pp 85If a received frame must pass 86through the A-MPDU receive reorder buffer then the mbuf 87must be marked with the 88.Dv M_AMPDU 89flag. 90Note that for the moment this is required of all frames received from 91a station and TID where a Block ACK stream is active, not just A-MPDU 92aggregates. 93It is sufficient to check for 94.Dv IEEE80211_NODE_HT 95in the 96.Vt ni_flags 97of the station's node table entry, any frames that do not require reorder 98processing will be dispatched with only minimal overhead. 99.Pp 100The 101.Vt rssi 102parameter is the Receive Signal Strength Indication of the frame 103measured in 0.5dBm units relative to the noise floor. 104The 105.Vt noise 106parameter is the best approximation of the noise floor in 107dBm units at the time the frame was received. 108RSSI and noise are used by the 109.Nm net80211 110layer to make scanning and roaming decisions in station mode 111and to do auto channel selection for hostap and similar modes. 112Otherwise the values are made available to user applications 113(with the rssi presented as a filtered average over the last ten values 114and the noise floor the last reported value). 115.Sh SEE ALSO 116.Xr ieee80211 9 117