pio.c

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/*

  Broadcom B43 wireless driver

  PIO data transfer

  Copyright (c) 2005-2008 Michael Buesch <[email protected]>

  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2 of the License, or
  (at your option) any later version.

  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; see the file COPYING.  If not, write to
  the Free Software Foundation, Inc., 51 Franklin Steet, Fifth Floor,
  Boston, MA 02110-1301, USA.

*/

#include "b43.h"
#include "pio.h"
#include "dma.h"
#include "main.h"
#include "xmit.h"

#include <linux/delay.h>
#include <linux/sched.h>
#include <linux/slab.h>


static u16 generate_cookie(struct b43_pio_txqueue *q,
               struct b43_pio_txpacket *pack)
{
    u16 cookie;

    /* Use the upper 4 bits of the cookie as
     * PIO controller ID and store the packet index number
     * in the lower 12 bits.
     * Note that the cookie must never be 0, as this
     * is a special value used in RX path.
     * It can also not be 0xFFFF because that is special
     * for multicast frames.
     */
    cookie = (((u16)q->index + 1) << 12);
    cookie |= pack->index;

    return cookie;
}

static
struct b43_pio_txqueue *parse_cookie(struct b43_wldev *dev,
                     u16 cookie,
                      struct b43_pio_txpacket **pack)
{
    struct b43_pio *pio = &dev->pio;
    struct b43_pio_txqueue *q = NULL;
    unsigned int pack_index;

    switch (cookie & 0xF000) {
    case 0x1000:
        q = pio->tx_queue_AC_BK;
        break;
    case 0x2000:
        q = pio->tx_queue_AC_BE;
        break;
    case 0x3000:
        q = pio->tx_queue_AC_VI;
        break;
    case 0x4000:
        q = pio->tx_queue_AC_VO;
        break;
    case 0x5000:
        q = pio->tx_queue_mcast;
        break;
    }
    if (B43_WARN_ON(!q))
        return NULL;
    pack_index = (cookie & 0x0FFF);
    if (B43_WARN_ON(pack_index >= ARRAY_SIZE(q->packets)))
        return NULL;
    *pack = &q->packets[pack_index];

    return q;
}

static u16 index_to_pioqueue_base(struct b43_wldev *dev,
                  unsigned int index)
{
    static const u16 bases[] = {
        B43_MMIO_PIO_BASE0,
        B43_MMIO_PIO_BASE1,
        B43_MMIO_PIO_BASE2,
        B43_MMIO_PIO_BASE3,
        B43_MMIO_PIO_BASE4,
        B43_MMIO_PIO_BASE5,
        B43_MMIO_PIO_BASE6,
        B43_MMIO_PIO_BASE7,
    };
    static const u16 bases_rev11[] = {
        B43_MMIO_PIO11_BASE0,
        B43_MMIO_PIO11_BASE1,
        B43_MMIO_PIO11_BASE2,
        B43_MMIO_PIO11_BASE3,
        B43_MMIO_PIO11_BASE4,
        B43_MMIO_PIO11_BASE5,
    };

    if (dev->dev->core_rev >= 11) {
        B43_WARN_ON(index >= ARRAY_SIZE(bases_rev11));
        return bases_rev11[index];
    }
    B43_WARN_ON(index >= ARRAY_SIZE(bases));
    return bases[index];
}

static u16 pio_txqueue_offset(struct b43_wldev *dev)
{
    if (dev->dev->core_rev >= 11)
        return 0x18;
    return 0;
}

static u16 pio_rxqueue_offset(struct b43_wldev *dev)
{
    if (dev->dev->core_rev >= 11)
        return 0x38;
    return 8;
}

static struct b43_pio_txqueue *b43_setup_pioqueue_tx(struct b43_wldev *dev,
                             unsigned int index)
{
    struct b43_pio_txqueue *q;
    struct b43_pio_txpacket *p;
    unsigned int i;

    q = kzalloc(sizeof(*q), GFP_KERNEL);
    if (!q)
        return NULL;
    q->dev = dev;
    q->rev = dev->dev->core_rev;
    q->mmio_base = index_to_pioqueue_base(dev, index) +
               pio_txqueue_offset(dev);
    q->index = index;

    q->free_packet_slots = B43_PIO_MAX_NR_TXPACKETS;
    if (q->rev >= 8) {
        q->buffer_size = 1920; //FIXME this constant is wrong.
    } else {
        q->buffer_size = b43_piotx_read16(q, B43_PIO_TXQBUFSIZE);
        q->buffer_size -= 80;
    }

    INIT_LIST_HEAD(&q->packets_list);
    for (i = 0; i < ARRAY_SIZE(q->packets); i++) {
        p = &(q->packets[i]);
        INIT_LIST_HEAD(&p->list);
        p->index = i;
        p->queue = q;
        list_add(&p->list, &q->packets_list);
    }

    return q;
}

static struct b43_pio_rxqueue *b43_setup_pioqueue_rx(struct b43_wldev *dev,
                             unsigned int index)
{
    struct b43_pio_rxqueue *q;

    q = kzalloc(sizeof(*q), GFP_KERNEL);
    if (!q)
        return NULL;
    q->dev = dev;
    q->rev = dev->dev->core_rev;
    q->mmio_base = index_to_pioqueue_base(dev, index) +
               pio_rxqueue_offset(dev);

    /* Enable Direct FIFO RX (PIO) on the engine. */
    b43_dma_direct_fifo_rx(dev, index, 1);

    return q;
}

static void b43_pio_cancel_tx_packets(struct b43_pio_txqueue *q)
{
    struct b43_pio_txpacket *pack;
    unsigned int i;

    for (i = 0; i < ARRAY_SIZE(q->packets); i++) {
        pack = &(q->packets[i]);
        if (pack->skb) {
            dev_kfree_skb_any(pack->skb);
            pack->skb = NULL;
        }
    }
}

static void b43_destroy_pioqueue_tx(struct b43_pio_txqueue *q,
                    const char *name)
{
    if (!q)
        return;
    b43_pio_cancel_tx_packets(q);
    kfree(q);
}

static void b43_destroy_pioqueue_rx(struct b43_pio_rxqueue *q,
                    const char *name)
{
    if (!q)
        return;
    kfree(q);
}

#define destroy_queue_tx(pio, queue) do {               \
    b43_destroy_pioqueue_tx((pio)->queue, __stringify(queue));  \
    (pio)->queue = NULL;                        \
  } while (0)

#define destroy_queue_rx(pio, queue) do {               \
    b43_destroy_pioqueue_rx((pio)->queue, __stringify(queue));  \
    (pio)->queue = NULL;                        \
  } while (0)

void b43_pio_free(struct b43_wldev *dev)
{
    struct b43_pio *pio;

    if (!b43_using_pio_transfers(dev))
        return;
    pio = &dev->pio;

    destroy_queue_rx(pio, rx_queue);
    destroy_queue_tx(pio, tx_queue_mcast);
    destroy_queue_tx(pio, tx_queue_AC_VO);
    destroy_queue_tx(pio, tx_queue_AC_VI);
    destroy_queue_tx(pio, tx_queue_AC_BE);
    destroy_queue_tx(pio, tx_queue_AC_BK);
}

int b43_pio_init(struct b43_wldev *dev)
{
    struct b43_pio *pio = &dev->pio;
    int err = -ENOMEM;

    b43_write32(dev, B43_MMIO_MACCTL, b43_read32(dev, B43_MMIO_MACCTL)
            & ~B43_MACCTL_BE);
    b43_shm_write16(dev, B43_SHM_SHARED, B43_SHM_SH_RXPADOFF, 0);

    pio->tx_queue_AC_BK = b43_setup_pioqueue_tx(dev, 0);
    if (!pio->tx_queue_AC_BK)
        goto out;

    pio->tx_queue_AC_BE = b43_setup_pioqueue_tx(dev, 1);
    if (!pio->tx_queue_AC_BE)
        goto err_destroy_bk;

    pio->tx_queue_AC_VI = b43_setup_pioqueue_tx(dev, 2);
    if (!pio->tx_queue_AC_VI)
        goto err_destroy_be;

    pio->tx_queue_AC_VO = b43_setup_pioqueue_tx(dev, 3);
    if (!pio->tx_queue_AC_VO)
        goto err_destroy_vi;

    pio->tx_queue_mcast = b43_setup_pioqueue_tx(dev, 4);
    if (!pio->tx_queue_mcast)
        goto err_destroy_vo;

    pio->rx_queue = b43_setup_pioqueue_rx(dev, 0);
    if (!pio->rx_queue)
        goto err_destroy_mcast;

    b43dbg(dev->wl, "PIO initialized\n");
    err = 0;
out:
    return err;

err_destroy_mcast:
    destroy_queue_tx(pio, tx_queue_mcast);
err_destroy_vo:
    destroy_queue_tx(pio, tx_queue_AC_VO);
err_destroy_vi:
    destroy_queue_tx(pio, tx_queue_AC_VI);
err_destroy_be:
    destroy_queue_tx(pio, tx_queue_AC_BE);
err_destroy_bk:
    destroy_queue_tx(pio, tx_queue_AC_BK);
    return err;
}

/* Static mapping of mac80211's queues (priorities) to b43 PIO queues. */
static struct b43_pio_txqueue *select_queue_by_priority(struct b43_wldev *dev,
                            u8 queue_prio)
{
    struct b43_pio_txqueue *q;

    if (dev->qos_enabled) {
        /* 0 = highest priority */
        switch (queue_prio) {
        default:
            B43_WARN_ON(1);
            /* fallthrough */
        case 0:
            q = dev->pio.tx_queue_AC_VO;
            break;
        case 1:
            q = dev->pio.tx_queue_AC_VI;
            break;
        case 2:
            q = dev->pio.tx_queue_AC_BE;
            break;
        case 3:
            q = dev->pio.tx_queue_AC_BK;
            break;
        }
    } else
        q = dev->pio.tx_queue_AC_BE;

    return q;
}

static u16 tx_write_2byte_queue(struct b43_pio_txqueue *q,
                u16 ctl,
                const void *_data,
                unsigned int data_len)
{
    struct b43_wldev *dev = q->dev;
    struct b43_wl *wl = dev->wl;
    const u8 *data = _data;

    ctl |= B43_PIO_TXCTL_WRITELO | B43_PIO_TXCTL_WRITEHI;
    b43_piotx_write16(q, B43_PIO_TXCTL, ctl);

    b43_block_write(dev, data, (data_len & ~1),
            q->mmio_base + B43_PIO_TXDATA,
            sizeof(u16));
    if (data_len & 1) {
        u8 *tail = wl->pio_tailspace;
        BUILD_BUG_ON(sizeof(wl->pio_tailspace) < 2);

        /* Write the last byte. */
        ctl &= ~B43_PIO_TXCTL_WRITEHI;
        b43_piotx_write16(q, B43_PIO_TXCTL, ctl);
        tail[0] = data[data_len - 1];
        tail[1] = 0;
        b43_block_write(dev, tail, 2,
                q->mmio_base + B43_PIO_TXDATA,
                sizeof(u16));
    }

    return ctl;
}

static void pio_tx_frame_2byte_queue(struct b43_pio_txpacket *pack,
                     const u8 *hdr, unsigned int hdrlen)
{
    struct b43_pio_txqueue *q = pack->queue;
    const char *frame = pack->skb->data;
    unsigned int frame_len = pack->skb->len;
    u16 ctl;

    ctl = b43_piotx_read16(q, B43_PIO_TXCTL);
    ctl |= B43_PIO_TXCTL_FREADY;
    ctl &= ~B43_PIO_TXCTL_EOF;

    /* Transfer the header data. */
    ctl = tx_write_2byte_queue(q, ctl, hdr, hdrlen);
    /* Transfer the frame data. */
    ctl = tx_write_2byte_queue(q, ctl, frame, frame_len);

    ctl |= B43_PIO_TXCTL_EOF;
    b43_piotx_write16(q, B43_PIO_TXCTL, ctl);
}

static u32 tx_write_4byte_queue(struct b43_pio_txqueue *q,
                u32 ctl,
                const void *_data,
                unsigned int data_len)
{
    struct b43_wldev *dev = q->dev;
    struct b43_wl *wl = dev->wl;
    const u8 *data = _data;

    ctl |= B43_PIO8_TXCTL_0_7 | B43_PIO8_TXCTL_8_15 |
           B43_PIO8_TXCTL_16_23 | B43_PIO8_TXCTL_24_31;
    b43_piotx_write32(q, B43_PIO8_TXCTL, ctl);

    b43_block_write(dev, data, (data_len & ~3),
            q->mmio_base + B43_PIO8_TXDATA,
            sizeof(u32));
    if (data_len & 3) {
        u8 *tail = wl->pio_tailspace;
        BUILD_BUG_ON(sizeof(wl->pio_tailspace) < 4);

        memset(tail, 0, 4);
        /* Write the last few bytes. */
        ctl &= ~(B43_PIO8_TXCTL_8_15 | B43_PIO8_TXCTL_16_23 |
             B43_PIO8_TXCTL_24_31);
        switch (data_len & 3) {
        case 3:
            ctl |= B43_PIO8_TXCTL_16_23 | B43_PIO8_TXCTL_8_15;
            tail[0] = data[data_len - 3];
            tail[1] = data[data_len - 2];
            tail[2] = data[data_len - 1];
            break;
        case 2:
            ctl |= B43_PIO8_TXCTL_8_15;
            tail[0] = data[data_len - 2];
            tail[1] = data[data_len - 1];
            break;
        case 1:
            tail[0] = data[data_len - 1];
            break;
        }
        b43_piotx_write32(q, B43_PIO8_TXCTL, ctl);
        b43_block_write(dev, tail, 4,
                q->mmio_base + B43_PIO8_TXDATA,
                sizeof(u32));
    }

    return ctl;
}

static void pio_tx_frame_4byte_queue(struct b43_pio_txpacket *pack,
                     const u8 *hdr, unsigned int hdrlen)
{
    struct b43_pio_txqueue *q = pack->queue;
    const char *frame = pack->skb->data;
    unsigned int frame_len = pack->skb->len;
    u32 ctl;

    ctl = b43_piotx_read32(q, B43_PIO8_TXCTL);
    ctl |= B43_PIO8_TXCTL_FREADY;
    ctl &= ~B43_PIO8_TXCTL_EOF;

    /* Transfer the header data. */
    ctl = tx_write_4byte_queue(q, ctl, hdr, hdrlen);
    /* Transfer the frame data. */
    ctl = tx_write_4byte_queue(q, ctl, frame, frame_len);

    ctl |= B43_PIO8_TXCTL_EOF;
    b43_piotx_write32(q, B43_PIO_TXCTL, ctl);
}

static int pio_tx_frame(struct b43_pio_txqueue *q,
            struct sk_buff *skb)
{
    struct b43_wldev *dev = q->dev;
    struct b43_wl *wl = dev->wl;
    struct b43_pio_txpacket *pack;
    u16 cookie;
    int err;
    unsigned int hdrlen;
    struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
    struct b43_txhdr *txhdr = (struct b43_txhdr *)wl->pio_scratchspace;

    B43_WARN_ON(list_empty(&q->packets_list));
    pack = list_entry(q->packets_list.next,
              struct b43_pio_txpacket, list);

    cookie = generate_cookie(q, pack);
    hdrlen = b43_txhdr_size(dev);
    BUILD_BUG_ON(sizeof(wl->pio_scratchspace) < sizeof(struct b43_txhdr));
    B43_WARN_ON(sizeof(wl->pio_scratchspace) < hdrlen);
    err = b43_generate_txhdr(dev, (u8 *)txhdr, skb,
                 info, cookie);
    if (err)
        return err;

    if (info->flags & IEEE80211_TX_CTL_SEND_AFTER_DTIM) {
        /* Tell the firmware about the cookie of the last
         * mcast frame, so it can clear the more-data bit in it. */
        b43_shm_write16(dev, B43_SHM_SHARED,
                B43_SHM_SH_MCASTCOOKIE, cookie);
    }

    pack->skb = skb;
    if (q->rev >= 8)
        pio_tx_frame_4byte_queue(pack, (const u8 *)txhdr, hdrlen);
    else
        pio_tx_frame_2byte_queue(pack, (const u8 *)txhdr, hdrlen);

    /* Remove it from the list of available packet slots.
     * It will be put back when we receive the status report. */
    list_del(&pack->list);

    /* Update the queue statistics. */
    q->buffer_used += roundup(skb->len + hdrlen, 4);
    q->free_packet_slots -= 1;

    return 0;
}

int b43_pio_tx(struct b43_wldev *dev, struct sk_buff *skb)
{
    struct b43_pio_txqueue *q;
    struct ieee80211_hdr *hdr;
    unsigned int hdrlen, total_len;
    int err = 0;
    struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);

    hdr = (struct ieee80211_hdr *)skb->data;

    if (info->flags & IEEE80211_TX_CTL_SEND_AFTER_DTIM) {
        /* The multicast queue will be sent after the DTIM. */
        q = dev->pio.tx_queue_mcast;
        /* Set the frame More-Data bit. Ucode will clear it
         * for us on the last frame. */
        hdr->frame_control |= cpu_to_le16(IEEE80211_FCTL_MOREDATA);
    } else {
        /* Decide by priority where to put this frame. */
        q = select_queue_by_priority(dev, skb_get_queue_mapping(skb));
    }

    hdrlen = b43_txhdr_size(dev);
    total_len = roundup(skb->len + hdrlen, 4);

    if (unlikely(total_len > q->buffer_size)) {
        err = -ENOBUFS;
        b43dbg(dev->wl, "PIO: TX packet longer than queue.\n");
        goto out;
    }
    if (unlikely(q->free_packet_slots == 0)) {
        err = -ENOBUFS;
        b43warn(dev->wl, "PIO: TX packet overflow.\n");
        goto out;
    }
    B43_WARN_ON(q->buffer_used > q->buffer_size);

    if (total_len > (q->buffer_size - q->buffer_used)) {
        /* Not enough memory on the queue. */
        err = -EBUSY;
        ieee80211_stop_queue(dev->wl->hw, skb_get_queue_mapping(skb));
        q->stopped = true;
        goto out;
    }

    /* Assign the queue number to the ring (if not already done before)
     * so TX status handling can use it. The mac80211-queue to b43-queue
     * mapping is static, so we don't need to store it per frame. */
    q->queue_prio = skb_get_queue_mapping(skb);

    err = pio_tx_frame(q, skb);
    if (unlikely(err == -ENOKEY)) {
        /* Drop this packet, as we don't have the encryption key
         * anymore and must not transmit it unencrypted. */
        dev_kfree_skb_any(skb);
        err = 0;
        goto out;
    }
    if (unlikely(err)) {
        b43err(dev->wl, "PIO transmission failure\n");
        goto out;
    }

    B43_WARN_ON(q->buffer_used > q->buffer_size);
    if (((q->buffer_size - q->buffer_used) < roundup(2 + 2 + 6, 4)) ||
        (q->free_packet_slots == 0)) {
        /* The queue is full. */
        ieee80211_stop_queue(dev->wl->hw, skb_get_queue_mapping(skb));
        q->stopped = true;
    }

out:
    return err;
}

void b43_pio_handle_txstatus(struct b43_wldev *dev,
                 const struct b43_txstatus *status)
{
    struct b43_pio_txqueue *q;
    struct b43_pio_txpacket *pack = NULL;
    unsigned int total_len;
    struct ieee80211_tx_info *info;

    q = parse_cookie(dev, status->cookie, &pack);
    if (unlikely(!q))
        return;
    B43_WARN_ON(!pack);

    info = IEEE80211_SKB_CB(pack->skb);

    b43_fill_txstatus_report(dev, info, status);

    total_len = pack->skb->len + b43_txhdr_size(dev);
    total_len = roundup(total_len, 4);
    q->buffer_used -= total_len;
    q->free_packet_slots += 1;

    ieee80211_tx_status(dev->wl->hw, pack->skb);
    pack->skb = NULL;
    list_add(&pack->list, &q->packets_list);

    if (q->stopped) {
        ieee80211_wake_queue(dev->wl->hw, q->queue_prio);
        q->stopped = false;
    }
}

/* Returns whether we should fetch another frame. */
static bool pio_rx_frame(struct b43_pio_rxqueue *q)
{
    struct b43_wldev *dev = q->dev;
    struct b43_wl *wl = dev->wl;
    u16 len;
    u32 macstat = 0;
    unsigned int i, padding;
    struct sk_buff *skb;
    const char *err_msg = NULL;
    struct b43_rxhdr_fw4 *rxhdr =
        (struct b43_rxhdr_fw4 *)wl->pio_scratchspace;
    size_t rxhdr_size = sizeof(*rxhdr);

    BUILD_BUG_ON(sizeof(wl->pio_scratchspace) < sizeof(*rxhdr));
    switch (dev->fw.hdr_format) {
    case B43_FW_HDR_410:
    case B43_FW_HDR_351:
        rxhdr_size -= sizeof(rxhdr->format_598) -
            sizeof(rxhdr->format_351);
        break;
    case B43_FW_HDR_598:
        break;
    }
    memset(rxhdr, 0, rxhdr_size);

    /* Check if we have data and wait for it to get ready. */
    if (q->rev >= 8) {
        u32 ctl;

        ctl = b43_piorx_read32(q, B43_PIO8_RXCTL);
        if (!(ctl & B43_PIO8_RXCTL_FRAMERDY))
            return 0;
        b43_piorx_write32(q, B43_PIO8_RXCTL,
                  B43_PIO8_RXCTL_FRAMERDY);
        for (i = 0; i < 10; i++) {
            ctl = b43_piorx_read32(q, B43_PIO8_RXCTL);
            if (ctl & B43_PIO8_RXCTL_DATARDY)
                goto data_ready;
            udelay(10);
        }
    } else {
        u16 ctl;

        ctl = b43_piorx_read16(q, B43_PIO_RXCTL);
        if (!(ctl & B43_PIO_RXCTL_FRAMERDY))
            return 0;
        b43_piorx_write16(q, B43_PIO_RXCTL,
                  B43_PIO_RXCTL_FRAMERDY);
        for (i = 0; i < 10; i++) {
            ctl = b43_piorx_read16(q, B43_PIO_RXCTL);
            if (ctl & B43_PIO_RXCTL_DATARDY)
                goto data_ready;
            udelay(10);
        }
    }
    b43dbg(q->dev->wl, "PIO RX timed out\n");
    return 1;
data_ready:

    /* Get the preamble (RX header) */
    if (q->rev >= 8) {
        b43_block_read(dev, rxhdr, rxhdr_size,
                   q->mmio_base + B43_PIO8_RXDATA,
                   sizeof(u32));
    } else {
        b43_block_read(dev, rxhdr, rxhdr_size,
                   q->mmio_base + B43_PIO_RXDATA,
                   sizeof(u16));
    }
    /* Sanity checks. */
    len = le16_to_cpu(rxhdr->frame_len);
    if (unlikely(len > 0x700)) {
        err_msg = "len > 0x700";
        goto rx_error;
    }
    if (unlikely(len == 0)) {
        err_msg = "len == 0";
        goto rx_error;
    }

    switch (dev->fw.hdr_format) {
    case B43_FW_HDR_598:
        macstat = le32_to_cpu(rxhdr->format_598.mac_status);
        break;
    case B43_FW_HDR_410:
    case B43_FW_HDR_351:
        macstat = le32_to_cpu(rxhdr->format_351.mac_status);
        break;
    }
    if (macstat & B43_RX_MAC_FCSERR) {
        if (!(q->dev->wl->filter_flags & FIF_FCSFAIL)) {
            /* Drop frames with failed FCS. */
            err_msg = "Frame FCS error";
            goto rx_error;
        }
    }

    /* We always pad 2 bytes, as that's what upstream code expects
     * due to the RX-header being 30 bytes. In case the frame is
     * unaligned, we pad another 2 bytes. */
    padding = (macstat & B43_RX_MAC_PADDING) ? 2 : 0;
    skb = dev_alloc_skb(len + padding + 2);
    if (unlikely(!skb)) {
        err_msg = "Out of memory";
        goto rx_error;
    }
    skb_reserve(skb, 2);
    skb_put(skb, len + padding);
    if (q->rev >= 8) {
        b43_block_read(dev, skb->data + padding, (len & ~3),
                   q->mmio_base + B43_PIO8_RXDATA,
                   sizeof(u32));
        if (len & 3) {
            u8 *tail = wl->pio_tailspace;
            BUILD_BUG_ON(sizeof(wl->pio_tailspace) < 4);

            /* Read the last few bytes. */
            b43_block_read(dev, tail, 4,
                       q->mmio_base + B43_PIO8_RXDATA,
                       sizeof(u32));
            switch (len & 3) {
            case 3:
                skb->data[len + padding - 3] = tail[0];
                skb->data[len + padding - 2] = tail[1];
                skb->data[len + padding - 1] = tail[2];
                break;
            case 2:
                skb->data[len + padding - 2] = tail[0];
                skb->data[len + padding - 1] = tail[1];
                break;
            case 1:
                skb->data[len + padding - 1] = tail[0];
                break;
            }
        }
    } else {
        b43_block_read(dev, skb->data + padding, (len & ~1),
                   q->mmio_base + B43_PIO_RXDATA,
                   sizeof(u16));
        if (len & 1) {
            u8 *tail = wl->pio_tailspace;
            BUILD_BUG_ON(sizeof(wl->pio_tailspace) < 2);

            /* Read the last byte. */
            b43_block_read(dev, tail, 2,
                       q->mmio_base + B43_PIO_RXDATA,
                       sizeof(u16));
            skb->data[len + padding - 1] = tail[0];
        }
    }

    b43_rx(q->dev, skb, rxhdr);

    return 1;

rx_error:
    if (err_msg)
        b43dbg(q->dev->wl, "PIO RX error: %s\n", err_msg);
    if (q->rev >= 8)
        b43_piorx_write32(q, B43_PIO8_RXCTL, B43_PIO8_RXCTL_DATARDY);
    else
        b43_piorx_write16(q, B43_PIO_RXCTL, B43_PIO_RXCTL_DATARDY);

    return 1;
}

void b43_pio_rx(struct b43_pio_rxqueue *q)
{
    unsigned int count = 0;
    bool stop;

    while (1) {
        stop = (pio_rx_frame(q) == 0);
        if (stop)
            break;
        cond_resched();
        if (WARN_ON_ONCE(++count > 10000))
            break;
    }
}

static void b43_pio_tx_suspend_queue(struct b43_pio_txqueue *q)
{
    if (q->rev >= 8) {
        b43_piotx_write32(q, B43_PIO8_TXCTL,
                  b43_piotx_read32(q, B43_PIO8_TXCTL)
                  | B43_PIO8_TXCTL_SUSPREQ);
    } else {
        b43_piotx_write16(q, B43_PIO_TXCTL,
                  b43_piotx_read16(q, B43_PIO_TXCTL)
                  | B43_PIO_TXCTL_SUSPREQ);
    }
}

static void b43_pio_tx_resume_queue(struct b43_pio_txqueue *q)
{
    if (q->rev >= 8) {
        b43_piotx_write32(q, B43_PIO8_TXCTL,
                  b43_piotx_read32(q, B43_PIO8_TXCTL)
                  & ~B43_PIO8_TXCTL_SUSPREQ);
    } else {
        b43_piotx_write16(q, B43_PIO_TXCTL,
                  b43_piotx_read16(q, B43_PIO_TXCTL)
                  & ~B43_PIO_TXCTL_SUSPREQ);
    }
}

void b43_pio_tx_suspend(struct b43_wldev *dev)
{
    b43_power_saving_ctl_bits(dev, B43_PS_AWAKE);
    b43_pio_tx_suspend_queue(dev->pio.tx_queue_AC_BK);
    b43_pio_tx_suspend_queue(dev->pio.tx_queue_AC_BE);
    b43_pio_tx_suspend_queue(dev->pio.tx_queue_AC_VI);
    b43_pio_tx_suspend_queue(dev->pio.tx_queue_AC_VO);
    b43_pio_tx_suspend_queue(dev->pio.tx_queue_mcast);
}

void b43_pio_tx_resume(struct b43_wldev *dev)
{
    b43_pio_tx_resume_queue(dev->pio.tx_queue_mcast);
    b43_pio_tx_resume_queue(dev->pio.tx_queue_AC_VO);
    b43_pio_tx_resume_queue(dev->pio.tx_queue_AC_VI);
    b43_pio_tx_resume_queue(dev->pio.tx_queue_AC_BE);
    b43_pio_tx_resume_queue(dev->pio.tx_queue_AC_BK);
    b43_power_saving_ctl_bits(dev, 0);
}