rx.c

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/*
 * This file is part of wl1251
 *
 * Copyright (c) 1998-2007 Texas Instruments Incorporated
 * Copyright (C) 2008 Nokia Corporation
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 *
 */

#include <linux/skbuff.h>
#include <linux/gfp.h>
#include <net/mac80211.h>

#include "wl1251.h"
#include "reg.h"
#include "io.h"
#include "rx.h"
#include "cmd.h"
#include "acx.h"

static void wl1251_rx_header(struct wl1251 *wl,
                 struct wl1251_rx_descriptor *desc)
{
    u32 rx_packet_ring_addr;

    rx_packet_ring_addr = wl->data_path->rx_packet_ring_addr;
    if (wl->rx_current_buffer)
        rx_packet_ring_addr += wl->data_path->rx_packet_ring_chunk_size;

    wl1251_mem_read(wl, rx_packet_ring_addr, desc, sizeof(*desc));
}

static void wl1251_rx_status(struct wl1251 *wl,
                 struct wl1251_rx_descriptor *desc,
                 struct ieee80211_rx_status *status,
                 u8 beacon)
{
    u64 mactime;
    int ret;

    memset(status, 0, sizeof(struct ieee80211_rx_status));

    status->band = IEEE80211_BAND_2GHZ;
    status->mactime = desc->timestamp;

    /*
     * The rx status timestamp is a 32 bits value while the TSF is a
     * 64 bits one.
     * For IBSS merging, TSF is mandatory, so we have to get it
     * somehow, so we ask for ACX_TSF_INFO.
     * That could be moved to the get_tsf() hook, but unfortunately,
     * this one must be atomic, while our SPI routines can sleep.
     */
    if ((wl->bss_type == BSS_TYPE_IBSS) && beacon) {
        ret = wl1251_acx_tsf_info(wl, &mactime);
        if (ret == 0)
            status->mactime = mactime;
    }

    status->signal = desc->rssi;

    /*
     * FIXME: guessing that snr needs to be divided by two, otherwise
     * the values don't make any sense
     */
    wl->noise = desc->rssi - desc->snr / 2;

    status->freq = ieee80211_channel_to_frequency(desc->channel,
                              status->band);

    status->flag |= RX_FLAG_MACTIME_MPDU;

    if (desc->flags & RX_DESC_ENCRYPTION_MASK) {
        status->flag |= RX_FLAG_IV_STRIPPED | RX_FLAG_MMIC_STRIPPED;

        if (likely(!(desc->flags & RX_DESC_DECRYPT_FAIL)))
            status->flag |= RX_FLAG_DECRYPTED;

        if (unlikely(desc->flags & RX_DESC_MIC_FAIL))
            status->flag |= RX_FLAG_MMIC_ERROR;
    }

    if (unlikely(!(desc->flags & RX_DESC_VALID_FCS)))
        status->flag |= RX_FLAG_FAILED_FCS_CRC;

    switch (desc->rate) {
        /* skip 1 and 12 Mbps because they have same value 0x0a */
    case RATE_2MBPS:
        status->rate_idx = 1;
        break;
    case RATE_5_5MBPS:
        status->rate_idx = 2;
        break;
    case RATE_11MBPS:
        status->rate_idx = 3;
        break;
    case RATE_6MBPS:
        status->rate_idx = 4;
        break;
    case RATE_9MBPS:
        status->rate_idx = 5;
        break;
    case RATE_18MBPS:
        status->rate_idx = 7;
        break;
    case RATE_24MBPS:
        status->rate_idx = 8;
        break;
    case RATE_36MBPS:
        status->rate_idx = 9;
        break;
    case RATE_48MBPS:
        status->rate_idx = 10;
        break;
    case RATE_54MBPS:
        status->rate_idx = 11;
        break;
    }

    /* for 1 and 12 Mbps we have to check the modulation */
    if (desc->rate == RATE_1MBPS) {
        if (!(desc->mod_pre & OFDM_RATE_BIT))
            /* CCK -> RATE_1MBPS */
            status->rate_idx = 0;
        else
            /* OFDM -> RATE_12MBPS */
            status->rate_idx = 6;
    }

    if (desc->mod_pre & SHORT_PREAMBLE_BIT)
        status->flag |= RX_FLAG_SHORTPRE;
}

static void wl1251_rx_body(struct wl1251 *wl,
               struct wl1251_rx_descriptor *desc)
{
    struct sk_buff *skb;
    struct ieee80211_rx_status status;
    u8 *rx_buffer, beacon = 0;
    u16 length, *fc;
    u32 curr_id, last_id_inc, rx_packet_ring_addr;

    length = WL1251_RX_ALIGN(desc->length  - PLCP_HEADER_LENGTH);
    curr_id = (desc->flags & RX_DESC_SEQNUM_MASK) >> RX_DESC_PACKETID_SHIFT;
    last_id_inc = (wl->rx_last_id + 1) % (RX_MAX_PACKET_ID + 1);

    if (last_id_inc != curr_id) {
        wl1251_warning("curr ID:%d, last ID inc:%d",
                   curr_id, last_id_inc);
        wl->rx_last_id = curr_id;
    } else {
        wl->rx_last_id = last_id_inc;
    }

    rx_packet_ring_addr = wl->data_path->rx_packet_ring_addr +
        sizeof(struct wl1251_rx_descriptor) + 20;
    if (wl->rx_current_buffer)
        rx_packet_ring_addr += wl->data_path->rx_packet_ring_chunk_size;

    skb = __dev_alloc_skb(length, GFP_KERNEL);
    if (!skb) {
        wl1251_error("Couldn't allocate RX frame");
        return;
    }

    rx_buffer = skb_put(skb, length);
    wl1251_mem_read(wl, rx_packet_ring_addr, rx_buffer, length);

    /* The actual length doesn't include the target's alignment */
    skb->len = desc->length  - PLCP_HEADER_LENGTH;

    fc = (u16 *)skb->data;

    if ((*fc & IEEE80211_FCTL_STYPE) == IEEE80211_STYPE_BEACON)
        beacon = 1;

    wl1251_rx_status(wl, desc, &status, beacon);

    wl1251_debug(DEBUG_RX, "rx skb 0x%p: %d B %s", skb, skb->len,
             beacon ? "beacon" : "");

    memcpy(IEEE80211_SKB_RXCB(skb), &status, sizeof(status));
    ieee80211_rx_ni(wl->hw, skb);
}

static void wl1251_rx_ack(struct wl1251 *wl)
{
    u32 data, addr;

    if (wl->rx_current_buffer) {
        addr = ACX_REG_INTERRUPT_TRIG_H;
        data = INTR_TRIG_RX_PROC1;
    } else {
        addr = ACX_REG_INTERRUPT_TRIG;
        data = INTR_TRIG_RX_PROC0;
    }

    wl1251_reg_write32(wl, addr, data);

    /* Toggle buffer ring */
    wl->rx_current_buffer = !wl->rx_current_buffer;
}


void wl1251_rx(struct wl1251 *wl)
{
    struct wl1251_rx_descriptor *rx_desc;

    if (wl->state != WL1251_STATE_ON)
        return;

    rx_desc = wl->rx_descriptor;

    /* We first read the frame's header */
    wl1251_rx_header(wl, rx_desc);

    /* Now we can read the body */
    wl1251_rx_body(wl, rx_desc);

    /* Finally, we need to ACK the RX */
    wl1251_rx_ack(wl);
}