path: root/drivers/net/wimax/i2400m/rx.c

/*
 * Intel Wireless WiMAX Connection 2400m
 * Handle incoming traffic and deliver it to the control or data planes
 *
 *
 * Copyright (C) 2007-2008 Intel Corporation. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   * Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *   * Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in
 *     the documentation and/or other materials provided with the
 *     distribution.
 *   * Neither the name of Intel Corporation nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 *
 * Intel Corporation <linux-wimax@intel.com>
 * Yanir Lubetkin <yanirx.lubetkin@intel.com>
 *  - Initial implementation
 * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
 *  - Use skb_clone(), break up processing in chunks
 *  - Split transport/device specific
 *  - Make buffer size dynamic to exert less memory pressure
 *  - RX reorder support
 *
 * This handles the RX path.
 *
 * We receive an RX message from the bus-specific driver, which
 * contains one or more payloads that have potentially different
 * destinataries (data or control paths).
 *
 * So we just take that payload from the transport specific code in
 * the form of an skb, break it up in chunks (a cloned skb each in the
 * case of network packets) and pass it to netdev or to the
 * command/ack handler (and from there to the WiMAX stack).
 *
 * PROTOCOL FORMAT
 *
 * The format of the buffer is:
 *
 * HEADER                      (struct i2400m_msg_hdr)
 * PAYLOAD DESCRIPTOR 0        (struct i2400m_pld)
 * PAYLOAD DESCRIPTOR 1
 * ...
 * PAYLOAD DESCRIPTOR N
 * PAYLOAD 0                   (raw bytes)
 * PAYLOAD 1
 * ...
 * PAYLOAD N
 *
 * See tx.c for a deeper description on alignment requirements and
 * other fun facts of it.
 *
 * DATA PACKETS
 *
 * In firmwares <= v1.3, data packets have no header for RX, but they
 * do for TX (currently unused).
 *
 * In firmware >= 1.4, RX packets have an extended header (16
 * bytes). This header conveys information for management of host
 * reordering of packets (the device offloads storage of the packets
 * for reordering to the host). Read below for more information.
 *
 * The header is used as dummy space to emulate an ethernet header and
 * thus be able to act as an ethernet device without having to reallocate.
 *
 * DATA RX REORDERING
 *
 * Starting in firmware v1.4, the device can deliver packets for
 * delivery with special reordering information; this allows it to
 * more effectively do packet management when some frames were lost in
 * the radio traffic.
 *
 * Thus, for RX packets that come out of order, the device gives the
 * driver enough information to queue them properly and then at some
 * point, the signal to deliver the whole (or part) of the queued
 * packets to the networking stack. There are 16 such queues.
 *
 * This only happens when a packet comes in with the "need reorder"
 * flag set in the RX header. When such bit is set, the following
 * operations might be indicated:
 *
 *  - reset queue: send all queued packets to the OS
 *
 *  - queue: queue a packet
 *
 *  - update ws: update the queue's window start and deliver queued
 *    packets that meet the criteria
 *
 *  - queue & update ws: queue a packet, update the window start and
 *    deliver queued packets that meet the criteria
 *
 * (delivery criteria: the packet's [normalized] sequence number is
 * lower than the new [normalized] window start).
 *
 * See the i2400m_roq_*() functions for details.
 *
 * ROADMAP
 *
 * i2400m_rx
 *   i2400m_rx_msg_hdr_check
 *   i2400m_rx_pl_descr_check
 *   i2400m_rx_payload
 *     i2400m_net_rx
 *     i2400m_rx_edata
 *       i2400m_net_erx
 *       i2400m_roq_reset
 *         i2400m_net_erx