tx.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/kernel.h>
#include <linux/module.h>

#include "wl1251.h"
#include "reg.h"
#include "tx.h"
#include "ps.h"
#include "io.h"

static bool wl1251_tx_double_buffer_busy(struct wl1251 *wl, u32 data_out_count)
{
    int used, data_in_count;

    data_in_count = wl->data_in_count;

    if (data_in_count < data_out_count)
        /* data_in_count has wrapped */
        data_in_count += TX_STATUS_DATA_OUT_COUNT_MASK + 1;

    used = data_in_count - data_out_count;

    WARN_ON(used < 0);
    WARN_ON(used > DP_TX_PACKET_RING_CHUNK_NUM);

    if (used >= DP_TX_PACKET_RING_CHUNK_NUM)
        return true;
    else
        return false;
}

static int wl1251_tx_path_status(struct wl1251 *wl)
{
    u32 status, addr, data_out_count;
    bool busy;

    addr = wl->data_path->tx_control_addr;
    status = wl1251_mem_read32(wl, addr);
    data_out_count = status & TX_STATUS_DATA_OUT_COUNT_MASK;
    busy = wl1251_tx_double_buffer_busy(wl, data_out_count);

    if (busy)
        return -EBUSY;

    return 0;
}

static int wl1251_tx_id(struct wl1251 *wl, struct sk_buff *skb)
{
    int i;

    for (i = 0; i < FW_TX_CMPLT_BLOCK_SIZE; i++)
        if (wl->tx_frames[i] == NULL) {
            wl->tx_frames[i] = skb;
            return i;
        }

    return -EBUSY;
}

static void wl1251_tx_control(struct tx_double_buffer_desc *tx_hdr,
                  struct ieee80211_tx_info *control, u16 fc)
{
    *(u16 *)&tx_hdr->control = 0;

    tx_hdr->control.rate_policy = 0;

    /* 802.11 packets */
    tx_hdr->control.packet_type = 0;

    if (control->flags & IEEE80211_TX_CTL_NO_ACK)
        tx_hdr->control.ack_policy = 1;

    tx_hdr->control.tx_complete = 1;

    if ((fc & IEEE80211_FTYPE_DATA) &&
        ((fc & IEEE80211_STYPE_QOS_DATA) ||
         (fc & IEEE80211_STYPE_QOS_NULLFUNC)))
        tx_hdr->control.qos = 1;
}

/* RSN + MIC = 8 + 8 = 16 bytes (worst case - AES). */
#define MAX_MSDU_SECURITY_LENGTH      16
#define MAX_MPDU_SECURITY_LENGTH      16
#define WLAN_QOS_HDR_LEN              26
#define MAX_MPDU_HEADER_AND_SECURITY  (MAX_MPDU_SECURITY_LENGTH + \
                       WLAN_QOS_HDR_LEN)
#define HW_BLOCK_SIZE                 252
static void wl1251_tx_frag_block_num(struct tx_double_buffer_desc *tx_hdr)
{
    u16 payload_len, frag_threshold, mem_blocks;
    u16 num_mpdus, mem_blocks_per_frag;

    frag_threshold = IEEE80211_MAX_FRAG_THRESHOLD;
    tx_hdr->frag_threshold = cpu_to_le16(frag_threshold);

    payload_len = le16_to_cpu(tx_hdr->length) + MAX_MSDU_SECURITY_LENGTH;

    if (payload_len > frag_threshold) {
        mem_blocks_per_frag =
            ((frag_threshold + MAX_MPDU_HEADER_AND_SECURITY) /
             HW_BLOCK_SIZE) + 1;
        num_mpdus = payload_len / frag_threshold;
        mem_blocks = num_mpdus * mem_blocks_per_frag;
        payload_len -= num_mpdus * frag_threshold;
        num_mpdus++;

    } else {
        mem_blocks_per_frag = 0;
        mem_blocks = 0;
        num_mpdus = 1;
    }

    mem_blocks += (payload_len / HW_BLOCK_SIZE) + 1;

    if (num_mpdus > 1)
        mem_blocks += min(num_mpdus, mem_blocks_per_frag);

    tx_hdr->num_mem_blocks = mem_blocks;
}

static int wl1251_tx_fill_hdr(struct wl1251 *wl, struct sk_buff *skb,
                  struct ieee80211_tx_info *control)
{
    struct tx_double_buffer_desc *tx_hdr;
    struct ieee80211_rate *rate;
    int id;
    u16 fc;

    if (!skb)
        return -EINVAL;

    id = wl1251_tx_id(wl, skb);
    if (id < 0)
        return id;

    fc = *(u16 *)skb->data;
    tx_hdr = (struct tx_double_buffer_desc *) skb_push(skb,
                               sizeof(*tx_hdr));

    tx_hdr->length = cpu_to_le16(skb->len - sizeof(*tx_hdr));
    rate = ieee80211_get_tx_rate(wl->hw, control);
    tx_hdr->rate = cpu_to_le16(rate->hw_value);
    tx_hdr->expiry_time = cpu_to_le32(1 << 16);
    tx_hdr->id = id;

    tx_hdr->xmit_queue = wl1251_tx_get_queue(skb_get_queue_mapping(skb));

    wl1251_tx_control(tx_hdr, control, fc);
    wl1251_tx_frag_block_num(tx_hdr);

    return 0;
}

/* We copy the packet to the target */
static int wl1251_tx_send_packet(struct wl1251 *wl, struct sk_buff *skb,
                 struct ieee80211_tx_info *control)
{
    struct tx_double_buffer_desc *tx_hdr;
    int len;
    u32 addr;

    if (!skb)
        return -EINVAL;

    tx_hdr = (struct tx_double_buffer_desc *) skb->data;

    if (control->control.hw_key &&
        control->control.hw_key->cipher == WLAN_CIPHER_SUITE_TKIP) {
        int hdrlen;
        __le16 fc;
        u16 length;
        u8 *pos;

        fc = *(__le16 *)(skb->data + sizeof(*tx_hdr));
        length = le16_to_cpu(tx_hdr->length) + WL1251_TKIP_IV_SPACE;
        tx_hdr->length = cpu_to_le16(length);

        hdrlen = ieee80211_hdrlen(fc);

        pos = skb_push(skb, WL1251_TKIP_IV_SPACE);
        memmove(pos, pos + WL1251_TKIP_IV_SPACE,
            sizeof(*tx_hdr) + hdrlen);
    }

    /* Revisit. This is a workaround for getting non-aligned packets.
       This happens at least with EAPOL packets from the user space.
       Our DMA requires packets to be aligned on a 4-byte boundary.
    */
    if (unlikely((long)skb->data & 0x03)) {
        int offset = (4 - (long)skb->data) & 0x03;
        wl1251_debug(DEBUG_TX, "skb offset %d", offset);

        /* check whether the current skb can be used */
        if (skb_cloned(skb) || (skb_tailroom(skb) < offset)) {
            struct sk_buff *newskb = skb_copy_expand(skb, 0, 3,
                                 GFP_KERNEL);

            if (unlikely(newskb == NULL)) {
                wl1251_error("Can't allocate skb!");
                return -EINVAL;
            }

            tx_hdr = (struct tx_double_buffer_desc *) newskb->data;

            dev_kfree_skb_any(skb);
            wl->tx_frames[tx_hdr->id] = skb = newskb;

            offset = (4 - (long)skb->data) & 0x03;
            wl1251_debug(DEBUG_TX, "new skb offset %d", offset);
        }

        /* align the buffer on a 4-byte boundary */
        if (offset) {
            unsigned char *src = skb->data;
            skb_reserve(skb, offset);
            memmove(skb->data, src, skb->len);
            tx_hdr = (struct tx_double_buffer_desc *) skb->data;
        }
    }

    /* Our skb->data at this point includes the HW header */
    len = WL1251_TX_ALIGN(skb->len);

    if (wl->data_in_count & 0x1)
        addr = wl->data_path->tx_packet_ring_addr +
            wl->data_path->tx_packet_ring_chunk_size;
    else
        addr = wl->data_path->tx_packet_ring_addr;

    wl1251_mem_write(wl, addr, skb->data, len);

    wl1251_debug(DEBUG_TX, "tx id %u skb 0x%p payload %u rate 0x%x "
             "queue %d", tx_hdr->id, skb, tx_hdr->length,
             tx_hdr->rate, tx_hdr->xmit_queue);

    return 0;
}

static void wl1251_tx_trigger(struct wl1251 *wl)
{
    u32 data, addr;

    if (wl->data_in_count & 0x1) {
        addr = ACX_REG_INTERRUPT_TRIG_H;
        data = INTR_TRIG_TX_PROC1;
    } else {
        addr = ACX_REG_INTERRUPT_TRIG;
        data = INTR_TRIG_TX_PROC0;
    }

    wl1251_reg_write32(wl, addr, data);

    /* Bumping data in */
    wl->data_in_count = (wl->data_in_count + 1) &
        TX_STATUS_DATA_OUT_COUNT_MASK;
}

/* caller must hold wl->mutex */
static int wl1251_tx_frame(struct wl1251 *wl, struct sk_buff *skb)
{
    struct ieee80211_tx_info *info;
    int ret = 0;
    u8 idx;

    info = IEEE80211_SKB_CB(skb);

    if (info->control.hw_key) {
        idx = info->control.hw_key->hw_key_idx;
        if (unlikely(wl->default_key != idx)) {
            ret = wl1251_acx_default_key(wl, idx);
            if (ret < 0)
                return ret;
        }
    }

    ret = wl1251_tx_path_status(wl);
    if (ret < 0)
        return ret;

    ret = wl1251_tx_fill_hdr(wl, skb, info);
    if (ret < 0)
        return ret;

    ret = wl1251_tx_send_packet(wl, skb, info);
    if (ret < 0)
        return ret;

    wl1251_tx_trigger(wl);

    return ret;
}

void wl1251_tx_work(struct work_struct *work)
{
    struct wl1251 *wl = container_of(work, struct wl1251, tx_work);
    struct sk_buff *skb;
    bool woken_up = false;
    int ret;

    mutex_lock(&wl->mutex);

    if (unlikely(wl->state == WL1251_STATE_OFF))
        goto out;

    while ((skb = skb_dequeue(&wl->tx_queue))) {
        if (!woken_up) {
            ret = wl1251_ps_elp_wakeup(wl);
            if (ret < 0)
                goto out;
            woken_up = true;
        }

        ret = wl1251_tx_frame(wl, skb);
        if (ret == -EBUSY) {
            skb_queue_head(&wl->tx_queue, skb);
            goto out;
        } else if (ret < 0) {
            dev_kfree_skb(skb);
            goto out;
        }
    }

out:
    if (woken_up)
        wl1251_ps_elp_sleep(wl);

    mutex_unlock(&wl->mutex);
}

static const char *wl1251_tx_parse_status(u8 status)
{
    /* 8 bit status field, one character per bit plus null */
    static char buf[9];
    int i = 0;

    memset(buf, 0, sizeof(buf));

    if (status & TX_DMA_ERROR)
        buf[i++] = 'm';
    if (status & TX_DISABLED)
        buf[i++] = 'd';
    if (status & TX_RETRY_EXCEEDED)
        buf[i++] = 'r';
    if (status & TX_TIMEOUT)
        buf[i++] = 't';
    if (status & TX_KEY_NOT_FOUND)
        buf[i++] = 'k';
    if (status & TX_ENCRYPT_FAIL)
        buf[i++] = 'e';
    if (status & TX_UNAVAILABLE_PRIORITY)
        buf[i++] = 'p';

    /* bit 0 is unused apparently */

    return buf;
}

static void wl1251_tx_packet_cb(struct wl1251 *wl,
                struct tx_result *result)
{
    struct ieee80211_tx_info *info;
    struct sk_buff *skb;
    int hdrlen;
    u8 *frame;

    skb = wl->tx_frames[result->id];
    if (skb == NULL) {
        wl1251_error("SKB for packet %d is NULL", result->id);
        return;
    }

    info = IEEE80211_SKB_CB(skb);

    if (!(info->flags & IEEE80211_TX_CTL_NO_ACK) &&
        (result->status == TX_SUCCESS))
        info->flags |= IEEE80211_TX_STAT_ACK;

    info->status.rates[0].count = result->ack_failures + 1;
    wl->stats.retry_count += result->ack_failures;

    /*
     * We have to remove our private TX header before pushing
     * the skb back to mac80211.
     */
    frame = skb_pull(skb, sizeof(struct tx_double_buffer_desc));
    if (info->control.hw_key &&
        info->control.hw_key->cipher == WLAN_CIPHER_SUITE_TKIP) {
        hdrlen = ieee80211_get_hdrlen_from_skb(skb);
        memmove(frame + WL1251_TKIP_IV_SPACE, frame, hdrlen);
        skb_pull(skb, WL1251_TKIP_IV_SPACE);
    }

    wl1251_debug(DEBUG_TX, "tx status id %u skb 0x%p failures %u rate 0x%x"
             " status 0x%x (%s)",
             result->id, skb, result->ack_failures, result->rate,
             result->status, wl1251_tx_parse_status(result->status));


    ieee80211_tx_status(wl->hw, skb);

    wl->tx_frames[result->id] = NULL;
}

/* Called upon reception of a TX complete interrupt */
void wl1251_tx_complete(struct wl1251 *wl)
{
    int i, result_index, num_complete = 0, queue_len;
    struct tx_result result[FW_TX_CMPLT_BLOCK_SIZE], *result_ptr;
    unsigned long flags;

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

    /* First we read the result */
    wl1251_mem_read(wl, wl->data_path->tx_complete_addr,
                result, sizeof(result));

    result_index = wl->next_tx_complete;

    for (i = 0; i < ARRAY_SIZE(result); i++) {
        result_ptr = &result[result_index];

        if (result_ptr->done_1 == 1 &&
            result_ptr->done_2 == 1) {
            wl1251_tx_packet_cb(wl, result_ptr);

            result_ptr->done_1 = 0;
            result_ptr->done_2 = 0;

            result_index = (result_index + 1) &
                (FW_TX_CMPLT_BLOCK_SIZE - 1);
            num_complete++;
        } else {
            break;
        }
    }

    queue_len = skb_queue_len(&wl->tx_queue);

    if ((num_complete > 0) && (queue_len > 0)) {
        /* firmware buffer has space, reschedule tx_work */
        wl1251_debug(DEBUG_TX, "tx_complete: reschedule tx_work");
        ieee80211_queue_work(wl->hw, &wl->tx_work);
    }

    if (wl->tx_queue_stopped &&
        queue_len <= WL1251_TX_QUEUE_LOW_WATERMARK) {
        /* tx_queue has space, restart queues */
        wl1251_debug(DEBUG_TX, "tx_complete: waking queues");
        spin_lock_irqsave(&wl->wl_lock, flags);
        ieee80211_wake_queues(wl->hw);
        wl->tx_queue_stopped = false;
        spin_unlock_irqrestore(&wl->wl_lock, flags);
    }

    /* Every completed frame needs to be acknowledged */
    if (num_complete) {
        /*
         * If we've wrapped, we have to clear
         * the results in 2 steps.
         */
        if (result_index > wl->next_tx_complete) {
            /* Only 1 write is needed */
            wl1251_mem_write(wl,
                     wl->data_path->tx_complete_addr +
                     (wl->next_tx_complete *
                      sizeof(struct tx_result)),
                     &result[wl->next_tx_complete],
                     num_complete *
                     sizeof(struct tx_result));


        } else if (result_index < wl->next_tx_complete) {
            /* 2 writes are needed */
            wl1251_mem_write(wl,
                     wl->data_path->tx_complete_addr +
                     (wl->next_tx_complete *
                      sizeof(struct tx_result)),
                     &result[wl->next_tx_complete],
                     (FW_TX_CMPLT_BLOCK_SIZE -
                      wl->next_tx_complete) *
                     sizeof(struct tx_result));

            wl1251_mem_write(wl,
                     wl->data_path->tx_complete_addr,
                     result,
                     (num_complete -
                      FW_TX_CMPLT_BLOCK_SIZE +
                      wl->next_tx_complete) *
                     sizeof(struct tx_result));

        } else {
            /* We have to write the whole array */
            wl1251_mem_write(wl,
                     wl->data_path->tx_complete_addr,
                     result,
                     FW_TX_CMPLT_BLOCK_SIZE *
                     sizeof(struct tx_result));
        }

    }

    wl->next_tx_complete = result_index;
}

/* caller must hold wl->mutex */
void wl1251_tx_flush(struct wl1251 *wl)
{
    int i;
    struct sk_buff *skb;
    struct ieee80211_tx_info *info;

    /* TX failure */
/*  control->flags = 0; FIXME */

    while ((skb = skb_dequeue(&wl->tx_queue))) {
        info = IEEE80211_SKB_CB(skb);

        wl1251_debug(DEBUG_TX, "flushing skb 0x%p", skb);

        if (!(info->flags & IEEE80211_TX_CTL_REQ_TX_STATUS))
                continue;

        ieee80211_tx_status(wl->hw, skb);
    }

    for (i = 0; i < FW_TX_CMPLT_BLOCK_SIZE; i++)
        if (wl->tx_frames[i] != NULL) {
            skb = wl->tx_frames[i];
            info = IEEE80211_SKB_CB(skb);

            if (!(info->flags & IEEE80211_TX_CTL_REQ_TX_STATUS))
                continue;

            ieee80211_tx_status(wl->hw, skb);
            wl->tx_frames[i] = NULL;
        }
}