// SPDX-License-Identifier: GPL-2.0-or-later
/*

  Broadcom B43 wireless driver

  DMA ringbuffer and descriptor allocation/management

  Copyright (c) 2005, 2006 Michael Buesch <m@bues.ch>

  Some code in this file is derived from the b44.c driver
  Copyright (C) 2002 David S. Miller
  Copyright (C) Pekka Pietikainen


*/

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

#include <linux/dma-mapping.h>
#include <linux/pci.h>
#include <linux/delay.h>
#include <linux/skbuff.h>
#include <linux/etherdevice.h>
#include <linux/slab.h>
#include <asm/div64.h>


/* Required number of TX DMA slots per TX frame.
 * This currently is 2, because we put the header and the ieee80211 frame
 * into separate slots. */
#define TX_SLOTS_PER_FRAME      2

static u32 b43_dma_address(struct b43_dma *dma, dma_addr_t dmaaddr,
                           enum b43_addrtype addrtype)
{
        u32 uninitialized_var(addr);

        switch (addrtype) {
        case B43_DMA_ADDR_LOW:
                addr = lower_32_bits(dmaaddr);
                if (dma->translation_in_low) {
                        addr &= ~SSB_DMA_TRANSLATION_MASK;
                        addr |= dma->translation;
                }
                break;
        case B43_DMA_ADDR_HIGH:
                addr = upper_32_bits(dmaaddr);
                if (!dma->translation_in_low) {
                        addr &= ~SSB_DMA_TRANSLATION_MASK;
                        addr |= dma->translation;
                }
                break;
        case B43_DMA_ADDR_EXT:
                if (dma->translation_in_low)
                        addr = lower_32_bits(dmaaddr);
                else
                        addr = upper_32_bits(dmaaddr);
                addr &= SSB_DMA_TRANSLATION_MASK;
                addr >>= SSB_DMA_TRANSLATION_SHIFT;
                break;
        }

        return addr;
}

/* 32bit DMA ops. */
static
struct b43_dmadesc_generic *op32_idx2desc(struct b43_dmaring *ring,
                                          int slot,
                                          struct b43_dmadesc_meta **meta)
{
        struct b43_dmadesc32 *desc;

        *meta = &(ring->meta[slot]);
        desc = ring->descbase;
        desc = &(desc[slot]);

        return (struct b43_dmadesc_generic *)desc;
}

static void op32_fill_descriptor(struct b43_dmaring *ring,
                                 struct b43_dmadesc_generic *desc,
                                 dma_addr_t dmaaddr, u16 bufsize,
                                 int start, int end, int irq)
{
        struct b43_dmadesc32 *descbase = ring->descbase;
        int slot;
        u32 ctl;
        u32 addr;
        u32 addrext;

        slot = (int)(&(desc->dma32) - descbase);
        B43_WARN_ON(!(slot >= 0 && slot < ring->nr_slots));

        addr = b43_dma_address(&ring->dev->dma, dmaaddr, B43_DMA_ADDR_LOW);
        addrext = b43_dma_address(&ring->dev->dma, dmaaddr, B43_DMA_ADDR_EXT);

        ctl = bufsize & B43_DMA32_DCTL_BYTECNT;
        if (slot == ring->nr_slots - 1)
                ctl |= B43_DMA32_DCTL_DTABLEEND;
        if (start)
                ctl |= B43_DMA32_DCTL_FRAMESTART;
        if (end)
                ctl |= B43_DMA32_DCTL_FRAMEEND;
        if (irq)
                ctl |= B43_DMA32_DCTL_IRQ;
        ctl |= (addrext << B43_DMA32_DCTL_ADDREXT_SHIFT)
            & B43_DMA32_DCTL_ADDREXT_MASK;

        desc->dma32.control = cpu_to_le32(ctl);
        desc->dma32.address = cpu_to_le32(addr);
}

static void op32_poke_tx(struct b43_dmaring *ring, int slot)
{
        b43_dma_write(ring, B43_DMA32_TXINDEX,
                      (u32) (slot * sizeof(struct b43_dmadesc32)));
}

static void op32_tx_suspend(struct b43_dmaring *ring)
{
        b43_dma_write(ring, B43_DMA32_TXCTL, b43_dma_read(ring, B43_DMA32_TXCTL)
                      | B43_DMA32_TXSUSPEND);
}

static void op32_tx_resume(struct b43_dmaring *ring)
{
        b43_dma_write(ring, B43_DMA32_TXCTL, b43_dma_read(ring, B43_DMA32_TXCTL)
                      & ~B43_DMA32_TXSUSPEND);
}

static int op32_get_current_rxslot(struct b43_dmaring *ring)
{
        u32 val;

        val = b43_dma_read(ring, B43_DMA32_RXSTATUS);
        val &= B43_DMA32_RXDPTR;

        return (val / sizeof(struct b43_dmadesc32));
}

static void op32_set_current_rxslot(struct b43_dmaring *ring, int slot)
{
        b43_dma_write(ring, B43_DMA32_RXINDEX,
                      (u32) (slot * sizeof(struct b43_dmadesc32)));
}

static const struct b43_dma_ops dma32_ops = {
        .idx2desc = op32_idx2desc,
        .fill_descriptor = op32_fill_descriptor,
        .poke_tx = op32_poke_tx,
        .tx_suspend = op32_tx_suspend,
        .tx_resume = op32_tx_resume,
        .get_current_rxslot = op32_get_current_rxslot,
        .set_current_rxslot = op32_set_current_rxslot,
};

/* 64bit DMA ops. */
static
struct b43_dmadesc_generic *op64_idx2desc(struct b43_dmaring *ring,
                                          int slot,
                                          struct b43_dmadesc_meta **meta)
{
        struct b43_dmadesc64 *desc;

        *meta = &(ring->meta[slot]);
        desc = ring->descbase;
        desc = &(desc[slot]);

        return (struct b43_dmadesc_generic *)desc;
}

static void op64_fill_descriptor(struct b43_dmaring *ring,
                                 struct b43_dmadesc_generic *desc,
                                 dma_addr_t dmaaddr, u16 bufsize,
                                 int start, int end, int irq)
{
        struct b43_dmadesc64 *descbase = ring->descbase;
        int slot;
        u32 ctl0 = 0, ctl1 = 0;
        u32 addrlo, addrhi;
        u32 addrext;

        slot = (int)(&(desc->dma64) - descbase);
        B43_WARN_ON(!(slot >= 0 && slot < ring->nr_slots));

        addrlo = b43_dma_address(&ring->dev->dma, dmaaddr, B43_DMA_ADDR_LOW);
        addrhi = b43_dma_address(&ring->dev->dma, dmaaddr, B43_DMA_ADDR_HIGH);
        addrext = b43_dma_address(&ring->dev->dma, dmaaddr, B43_DMA_ADDR_EXT);

        if (slot == ring->nr_slots - 1)
                ctl0 |= B43_DMA64_DCTL0_DTABLEEND;
        if (start)
                ctl0 |= B43_DMA64_DCTL0_FRAMESTART;
        if (end)
                ctl0 |= B43_DMA64_DCTL0_FRAMEEND;
        if (irq)
                ctl0 |= B43_DMA64_DCTL0_IRQ;
        ctl1 |= bufsize & B43_DMA64_DCTL1_BYTECNT;
        ctl1 |= (addrext << B43_DMA64_DCTL1_ADDREXT_SHIFT)
            & B43_DMA64_DCTL1_ADDREXT_MASK;

        desc->dma64.control0 = cpu_to_le32(ctl0);
        desc->dma64.control1 = cpu_to_le32(ctl1);
        desc->dma64.address_low = cpu_to_le32(addrlo);
        desc->dma64.address_high = cpu_to_le32(addrhi);
}

static void op64_poke_tx(struct b43_dmaring *ring, int slot)
{
        b43_dma_write(ring, B43_DMA64_TXINDEX,
                      (u32) (slot * sizeof(struct b43_dmadesc64)));
}

static void op64_tx_suspend(struct b43_dmaring *ring)
{
        b43_dma_write(ring, B43_DMA64_TXCTL, b43_dma_read(ring, B43_DMA64_TXCTL)
                      | B43_DMA64_TXSUSPEND);
}

static void op64_tx_resume(struct b43_dmaring *ring)
{
        b43_dma_write(ring, B43_DMA64_TXCTL, b43_dma_read(ring, B43_DMA64_TXCTL)
                      & ~B43_DMA64_TXSUSPEND);
}

static int op64_get_current_rxslot(struct b43_dmaring *ring)
{
        u32 val;

        val = b43_dma_read(ring, B43_DMA64_RXSTATUS);
        val &= B43_DMA64_RXSTATDPTR;

        return (val / sizeof(struct b43_dmadesc64));
}

static void op64_set_current_rxslot(struct b43_dmaring *ring, int slot)
{
        b43_dma_write(ring, B43_DMA64_RXINDEX,
                      (u32) (slot * sizeof(struct b43_dmadesc64)));
}

static const struct b43_dma_ops dma64_ops = {
        .idx2desc = op64_idx2desc,
        .fill_descriptor = op64_fill_descriptor,
        .poke_tx = op64_poke_tx,
        .tx_suspend = op64_tx_suspend,
        .tx_resume = op64_tx_resume,
        .get_current_rxslot = op64_get_current_rxslot,
        .set_current_rxslot = op64_set_current_rxslot,
};

static inline int free_slots(struct b43_dmaring *ring)
{
        return (ring->nr_slots - ring->used_slots);
}

static inline int next_slot(struct b43_dmaring *ring, int slot)
{
        B43_WARN_ON(!(slot >= -1 && slot <= ring->nr_slots - 1));
        if (slot == ring->nr_slots - 1)
                return 0;
        return slot + 1;
}

static inline int prev_slot(struct b43_dmaring *ring, int slot)
{
        B43_WARN_ON(!(slot >= 0 && slot <= ring->nr_slots - 1));
        if (slot == 0)
                return ring->nr_slots - 1;
        return slot - 1;
}

#ifdef CONFIG_B43_DEBUG
static void update_max_used_slots(struct b43_dmaring *ring,
                                  int current_used_slots)
{
        if (current_used_slots <= ring->max_used_slots)
                return;
        ring->max_used_slots = current_used_slots;
        if (b43_debug(ring->dev, B43_DBG_DMAVERBOSE)) {
                b43dbg(ring->dev->wl,
                       "max_used_slots increased to %d on %s ring %d\n",
                       ring->max_used_slots,
                       ring->tx ? "TX" : "RX", ring->index);
        }
}
#else
static inline
    void update_max_used_slots(struct b43_dmaring *ring, int current_used_slots)
{
}
#endif /* DEBUG */

/* Request a slot for usage. */
static inline int request_slot(struct b43_dmaring *ring)
{
        int slot;

        B43_WARN_ON(!ring->tx);
        B43_WARN_ON(ring->stopped);
        B43_WARN_ON(free_slots(ring) == 0);

        slot = next_slot(ring, ring->current_slot);
        ring->current_slot = slot;
        ring->used_slots++;

        update_max_used_slots(ring, ring->used_slots);

        return slot;
}

static u16 b43_dmacontroller_base(enum b43_dmatype type, int controller_idx)
{
        static const u16 map64[] = {
                B43_MMIO_DMA64_BASE0,
                B43_MMIO_DMA64_BASE1,
                B43_MMIO_DMA64_BASE2,
                B43_MMIO_DMA64_BASE3,
                B43_MMIO_DMA64_BASE4,
                B43_MMIO_DMA64_BASE5,
        };
        static const u16 map32[] = {
                B43_MMIO_DMA32_BASE0,
                B43_MMIO_DMA32_BASE1,
                B43_MMIO_DMA32_BASE2,
                B43_MMIO_DMA32_BASE3,
                B43_MMIO_DMA32_BASE4,
                B43_MMIO_DMA32_BASE5,
        };

        if (type == B43_DMA_64BIT) {
                B43_WARN_ON(!(controller_idx >= 0 &&
                              controller_idx < ARRAY_SIZE(map64)));
                return map64[controller_idx];
        }
        B43_WARN_ON(!(controller_idx >= 0 &&
                      controller_idx < ARRAY_SIZE(map32)));
        return map32[controller_idx];
}

static inline
    dma_addr_t map_descbuffer(struct b43_dmaring *ring,
                              unsigned char *buf, size_t len, int tx)
{
        dma_addr_t dmaaddr;

        if (tx) {
                dmaaddr = dma_map_single(ring->dev->dev->dma_dev,
                                         buf, len, DMA_TO_DEVICE);
        } else {
                dmaaddr = dma_map_single(ring->dev->dev->dma_dev,
                                         buf, len, DMA_FROM_DEVICE);
        }

        return dmaaddr;
}

static inline
    void unmap_descbuffer(struct b43_dmaring *ring,
                          dma_addr_t addr, size_t len, int tx)
{
        if (tx) {
                dma_unmap_single(ring->dev->dev->dma_dev,
                                 addr, len, DMA_TO_DEVICE);
        } else {
                dma_unmap_single(ring->dev->dev->dma_dev,
                                 addr, len, DMA_FROM_DEVICE);
        }
}

static inline
    void sync_descbuffer_for_cpu(struct b43_dmaring *ring,
                                 dma_addr_t addr, size_t len)
{
        B43_WARN_ON(ring->tx);
        dma_sync_single_for_cpu(ring->dev->dev->dma_dev,
                                    addr, len, DMA_FROM_DEVICE);
}

static inline
    void sync_descbuffer_for_device(struct b43_dmaring *ring,
                                    dma_addr_t addr, size_t len)
{
        B43_WARN_ON(ring->tx);
        dma_sync_single_for_device(ring->dev->dev->dma_dev,
                                   addr, len, DMA_FROM_DEVICE);
}

static inline
    void free_descriptor_buffer(struct b43_dmaring *ring,
                                struct b43_dmadesc_meta *meta)
{
        if (meta->skb) {
                if (ring->tx)
                        ieee80211_free_txskb(ring->dev->wl->hw, meta->skb);
                else
                        dev_kfree_skb_any(meta->skb);
                meta->skb = NULL;
        }
}

static int alloc_ringmemory(struct b43_dmaring *ring)
{
        /* The specs call for 4K buffers for 30- and 32-bit DMA with 4K
         * alignment and 8K buffers for 64-bit DMA with 8K alignment.
         * In practice we could use smaller buffers for the latter, but the
         * alignment is really important because of the hardware bug. If bit
         * 0x00001000 is used in DMA address, some hardware (like BCM4331)
         * copies that bit into B43_DMA64_RXSTATUS and we get false values from
         * B43_DMA64_RXSTATDPTR. Let's just use 8K buffers even if we don't use
         * more than 256 slots for ring.
         */
        u16 ring_mem_size = (ring->type == B43_DMA_64BIT) ?
                                B43_DMA64_RINGMEMSIZE : B43_DMA32_RINGMEMSIZE;

        ring->descbase = dma_alloc_coherent(ring->dev->dev->dma_dev,
                                            ring_mem_size, &(ring->dmabase),
                                            GFP_KERNEL);
        if (!ring->descbase)
                return -ENOMEM;

        return 0;
}

static void free_ringmemory(struct b43_dmaring *ring)
{
        u16 ring_mem_size = (ring->type == B43_DMA_64BIT) ?
                                B43_DMA64_RINGMEMSIZE : B43_DMA32_RINGMEMSIZE;
        dma_free_coherent(ring->dev->dev->dma_dev, ring_mem_size,
                          ring->descbase, ring->dmabase);
}

/* Reset the RX DMA channel */
static int b43_dmacontroller_rx_reset(struct b43_wldev *dev, u16 mmio_base,
                                      enum b43_dmatype type)
{
        int i;
        u32 value;
        u16 offset;

        might_sleep();

        offset = (type == B43_DMA_64BIT) ? B43_DMA64_RXCTL : B43_DMA32_RXCTL;
        b43_write32(dev, mmio_base + offset, 0);
        for (i = 0; i < 10; i++) {
                offset = (type == B43_DMA_64BIT) ? B43_DMA64_RXSTATUS :
                                                   B43_DMA32_RXSTATUS;
                value = b43_read32(dev, mmio_base + offset);
                if (type == B43_DMA_64BIT) {
                        value &= B43_DMA64_RXSTAT;
                        if (value == B43_DMA64_RXSTAT_DISABLED) {
                                i = -1;
                                break;
                        }
                } else {
                        value &= B43_DMA32_RXSTATE;
                        if (value == B43_DMA32_RXSTAT_DISABLED) {
                                i = -1;
                                break;
                        }
                }
                msleep(1);
        }
        if (i != -1) {
                b43err(dev->wl, "DMA RX reset timed out\n");
                return -ENODEV;
        }

        return 0;
}

/* Reset the TX DMA channel */
static int b43_dmacontroller_tx_reset(struct b43_wldev *dev, u16 mmio_base,
                                      enum b43_dmatype type)
{
        int i;
        u32 value;
        u16 offset;

        might_sleep();

        for (i = 0; i < 10; i++) {
                offset = (type == B43_DMA_64BIT) ? B43_DMA64_TXSTATUS :
                                                   B43_DMA32_TXSTATUS;
                value = b43_read32(dev, mmio_base + offset);
                if (type == B43_DMA_64BIT) {
                        value &= B43_DMA64_TXSTAT;
                        if (value == B43_DMA64_TXSTAT_DISABLED ||
                            value == B43_DMA64_TXSTAT_IDLEWAIT ||
                            value == B43_DMA64_TXSTAT_STOPPED)
                                break;
                } else {
                        value &= B43_DMA32_TXSTATE;
                        if (value == B43_DMA32_TXSTAT_DISABLED ||
                            value == B43_DMA32_TXSTAT_IDLEWAIT ||
                            value == B43_DMA32_TXSTAT_STOPPED)
                                break;
                }
                msleep(1);
        }
        offset = (type == B43_DMA_64BIT) ? B43_DMA64_TXCTL : B43_DMA32_TXCTL;
        b43_write32(dev, mmio_base + offset, 0);
        for (i = 0; i < 10; i++) {
                offset = (type == B43_DMA_64BIT) ? B43_DMA64_TXSTATUS :
                                                   B43_DMA32_TXSTATUS;
                value = b43_read32(dev, mmio_base + offset);
                if (type == B43_DMA_64BIT) {
                        value &= B43_DMA64_TXSTAT;
                        if (value == B43_DMA64_TXSTAT_DISABLED) {
                                i = -1;
                                break;
                        }
                } else {
                        value &= B43_DMA32_TXSTATE;
                        if (value == B43_DMA32_TXSTAT_DISABLED) {
                                i = -1;
                                break;
                        }
                }
                msleep(1);
        }
        if (i != -1) {
                b43err(dev->wl, "DMA TX reset timed out\n");
                return -ENODEV;
        }
        /* ensure the reset is completed. */
        msleep(1);

        return 0;
}

/* Check if a DMA mapping address is invalid. */
static bool b43_dma_mapping_error(struct b43_dmaring *ring,
                                  dma_addr_t addr,
                                  size_t buffersize, bool dma_to_device)
{
        if (unlikely(dma_mapping_error(ring->dev->dev->dma_dev, addr)))
                return true;

        switch (ring->type) {
        case B43_DMA_30BIT:
                if ((u64)addr + buffersize > (1ULL << 30))
                        goto address_error;
                break;
        case B43_DMA_32BIT:
                if ((u64)addr + buffersize > (1ULL << 32))
                        goto address_error;
                break;
        case B43_DMA_64BIT:
                /* Currently we can't have addresses beyond
                 * 64bit in the kernel. */
                break;
        }

        /* The address is OK. */
        return false;

address_error:
        /* We can't support this address. Unmap it again. */
        unmap_descbuffer(ring, addr, buffersize, dma_to_device);

        return true;
}

static bool b43_rx_buffer_is_poisoned(struct b43_dmaring *ring, struct sk_buff *skb)
{
        unsigned char *f = skb->data + ring->frameoffset;

        return ((f[0] & f[1] & f[2] & f[3] & f[4] & f[5] & f[6] & f[7]) == 0xFF);
}

static void b43_poison_rx_buffer(struct b43_dmaring *ring, struct sk_buff *skb)
{
        struct b43_rxhdr_fw4 *rxhdr;
        unsigned char *frame;

        /* This poisons the RX buffer to detect DMA failures. */

        rxhdr = (struct b43_rxhdr_fw4 *)(skb->data);
        rxhdr->frame_len = 0;

        B43_WARN_ON(ring->rx_buffersize < ring->frameoffset + sizeof(struct b43_plcp_hdr6) + 2);
        frame = skb->data + ring->frameoffset;
        memset(frame, 0xFF, sizeof(struct b43_plcp_hdr6) + 2 /* padding */);
}

static int setup_rx_descbuffer(struct b43_dmaring *ring,
                               struct b43_dmadesc_generic *desc,
                               struct b43_dmadesc_meta *meta, gfp_t gfp_flags)
{
        dma_addr_t dmaaddr;
        struct sk_buff *skb;

        B43_WARN_ON(ring->tx);

        skb = __dev_alloc_skb(ring->rx_buffersize, gfp_flags);
        if (unlikely(!skb))
                return -ENOMEM;
        b43_poison_rx_buffer(ring, skb);
        dmaaddr = map_descbuffer(ring, skb->data, ring->rx_buffersize, 0);
        if (b43_dma_mapping_error(ring, dmaaddr, ring->rx_buffersize, 0)) {
                /* ugh. try to realloc in zone_dma */
                gfp_flags |= GFP_DMA;

                dev_kfree_skb_any(skb);

                skb = __dev_alloc_skb(ring->rx_buffersize, gfp_flags);
                if (unlikely(!skb))
                        return -ENOMEM;
                b43_poison_rx_buffer(ring, skb);
                dmaaddr = map_descbuffer(ring, skb->data,
                                         ring->rx_buffersize, 0);
                if (b43_dma_mapping_error(ring, dmaaddr, ring->rx_buffersize, 0)) {
                        b43err(ring->dev->wl, "RX DMA buffer allocation failed\n");
                        dev_kfree_skb_any(skb);
                        return -EIO;
                }
        }

        meta->skb = skb;
        meta->dmaaddr = dmaaddr;
        ring->ops->fill_descriptor(ring, desc, dmaaddr,
                                   ring->rx_buffersize, 0, 0, 0);

        return 0;
}

/* Allocate the initial descbuffers.
 * This is used for an RX ring only.
 */
static int alloc_initial_descbuffers(struct b43_dmaring *ring)
{
        int i, err = -ENOMEM;
        struct b43_dmadesc_generic *desc;
        struct b43_dmadesc_meta *meta;

        for (i = 0; i < ring->nr_slots; i++) {
                desc = ring->ops->idx2desc(ring, i, &meta);

                err = setup_rx_descbuffer(ring, desc, meta, GFP_KERNEL);
                if (err) {
                        b43err(ring->dev->wl,
                               "Failed to allocate initial descbuffers\n");
                        goto err_unwind;
                }
        }
        mb();
        ring->used_slots = ring->nr_slots;
        err = 0;
      out:
        return err;

      err_unwind:
        for (i--; i >= 0; i--) {
                desc = ring->ops->idx2desc(ring, i, &meta);

                unmap_descbuffer(ring, meta->dmaaddr, ring->rx_buffersize, 0);
                dev_kfree_skb(meta->skb);
        }
        goto out;
}

/* Do initial setup of the DMA controller.
 * Reset the controller, write the ring busaddress
 * and switch the "enable" bit on.
 */
static int dmacontroller_setup(struct b43_dmaring *ring)
{
        int err = 0;
        u32 value;
        u32 addrext;
        bool parity = ring->dev->dma.parity;
        u32 addrlo;
        u32 addrhi;

        if (ring->tx) {
                if (ring->type == B43_DMA_64BIT) {
                        u64 ringbase = (u64) (ring->dmabase);
                        addrext = b43_dma_address(&ring->dev->dma, ringbase, B43_DMA_ADDR_EXT);
                        addrlo = b43_dma_address(&ring->dev->dma, ringbase, B43_DMA_ADDR_LOW);
                        addrhi = b43_dma_address(&ring->dev->dma, ringbase, B43_DMA_ADDR_HIGH);

                        value = B43_DMA64_TXENABLE;
                        value |= (addrext << B43_DMA64_TXADDREXT_SHIFT)
                            & B43_DMA64_TXADDREXT_MASK;
                        if (!parity)
                                value |= B43_DMA64_TXPARITYDISABLE;
                        b43_dma_write(ring, B43_DMA64_TXCTL, value);
                        b43_dma_write(ring, B43_DMA64_TXRINGLO, addrlo);
                        b43_dma_write(ring, B43_DMA64_TXRINGHI, addrhi);
                } else {
                        u32 ringbase = (u32) (ring->dmabase);
                        addrext = b43_dma_address(&ring->dev->dma, ringbase, B43_DMA_ADDR_EXT);
                        addrlo = b43_dma_address(&ring->dev->dma, ringbase, B43_DMA_ADDR_LOW);

                        value = B43_DMA32_TXENABLE;
                        value |= (addrext << B43_DMA32_TXADDREXT_SHIFT)
                            & B43_DMA32_TXADDREXT_MASK;
                        if (!parity)
                                value |= B43_DMA32_TXPARITYDISABLE;
                        b43_dma_write(ring, B43_DMA32_TXCTL, value);
                        b43_dma_write(ring, B43_DMA32_TXRING, addrlo);
                }
        } else {
                err = alloc_initial_descbuffers(ring);
                if (err)
                        goto out;
                if (ring->type == B43_DMA_64BIT) {
                        u64 ringbase = (u64) (ring->dmabase);
                        addrext = b43_dma_address(&ring->dev->dma, ringbase, B43_DMA_ADDR_EXT);
                        addrlo = b43_dma_address(&ring->dev->dma, ringbase, B43_DMA_ADDR_LOW);
                        addrhi = b43_dma_address(&ring->dev->dma, ringbase, B43_DMA_ADDR_HIGH);

                        value = (ring->frameoffset << B43_DMA64_RXFROFF_SHIFT);
                        value |= B43_DMA64_RXENABLE;
                        value |= (addrext << B43_DMA64_RXADDREXT_SHIFT)
                            & B43_DMA64_RXADDREXT_MASK;
                        if (!parity)
                                value |= B43_DMA64_RXPARITYDISABLE;
                        b43_dma_write(ring, B43_DMA64_RXCTL, value);
                        b43_dma_write(ring, B43_DMA64_RXRINGLO, addrlo);
                        b43_dma_write(ring, B43_DMA64_RXRINGHI, addrhi);
                        b43_dma_write(ring, B43_DMA64_RXINDEX, ring->nr_slots *
                                      sizeof(struct b43_dmadesc64));
                } else {
                        u32 ringbase = (u32) (ring->dmabase);
                        addrext = b43_dma_address(&ring->dev->dma, ringbase, B43_DMA_ADDR_EXT);
                        addrlo = b43_dma_address(&ring->dev->dma, ringbase, B43_DMA_ADDR_LOW);

                        value = (ring->frameoffset << B43_DMA32_RXFROFF_SHIFT);
                        value |= B43_DMA32_RXENABLE;
                        value |= (addrext << B43_DMA32_RXADDREXT_SHIFT)
                            & B43_DMA32_RXADDREXT_MASK;
                        if (!parity)
                                value |= B43_DMA32_RXPARITYDISABLE;
                        b43_dma_write(ring, B43_DMA32_RXCTL, value);
                        b43_dma_write(ring, B43_DMA32_RXRING, addrlo);
                        b43_dma_write(ring, B43_DMA32_RXINDEX, ring->nr_slots *
                                      sizeof(struct b43_dmadesc32));
                }
        }

out:
        return err;
}

/* Shutdown the DMA controller. */
static void dmacontroller_cleanup(struct b43_dmaring *ring)
{
        if (ring->tx) {
                b43_dmacontroller_tx_reset(ring->dev, ring->mmio_base,
                                           ring->type);
                if (ring->type == B43_DMA_64BIT) {
                        b43_dma_write(ring, B43_DMA64_TXRINGLO, 0);
                        b43_dma_write(ring, B43_DMA64_TXRINGHI, 0);
                } else
                        b43_dma_write(ring, B43_DMA32_TXRING, 0);
        } else {
                b43_dmacontroller_rx_reset(ring->dev, ring->mmio_base,
                                           ring->type);
                if (ring->type == B43_DMA_64BIT) {
                        b43_dma_write(ring, B43_DMA64_RXRINGLO, 0);
                        b43_dma_write(ring, B43_DMA64_RXRINGHI, 0);
                } else
                        b43_dma_write(ring, B43_DMA32_RXRING, 0);
        }
}

static void free_all_descbuffers(struct b43_dmaring *ring)
{
        struct b43_dmadesc_meta *meta;
        int i;

        if (!ring->used_slots)
                return;
        for (i = 0; i < ring->nr_slots; i++) {
                /* get meta - ignore returned value */
                ring->ops->idx2desc(ring, i, &meta);

                if (!meta->skb || b43_dma_ptr_is_poisoned(meta->skb)) {
                        B43_WARN_ON(!ring->tx);
                        continue;
                }
                if (ring->tx) {
                        unmap_descbuffer(ring, meta->dmaaddr,
                                         meta->skb->len, 1);
                } else {
                        unmap_descbuffer(ring, meta->dmaaddr,
                                         ring->rx_buffersize, 0);
                }
                free_descriptor_buffer(ring, meta);
        }
}

static enum b43_dmatype b43_engine_type(struct b43_wldev *dev)
{
        u32 tmp;
        u16 mmio_base;

        switch (dev->dev->bus_type) {
#ifdef CONFIG_B43_BCMA
        case B43_BUS_BCMA:
                tmp = bcma_aread32(dev->dev->bdev, BCMA_IOST);
                if (tmp & BCMA_IOST_DMA64)
                        return B43_DMA_64BIT;
                break;
#endif
#ifdef CONFIG_B43_SSB
        case B43_BUS_SSB:
                tmp = ssb_read32(dev->dev->sdev, SSB_TMSHIGH);
                if (tmp & SSB_TMSHIGH_DMA64)
                        return B43_DMA_64BIT;
                break;
#endif
        }

        mmio_base = b43_dmacontroller_base(0, 0);
        b43_write32(dev, mmio_base + B43_DMA32_TXCTL, B43_DMA32_TXADDREXT_MASK);
        tmp = b43_read32(dev, mmio_base + B43_DMA32_TXCTL);
        if (tmp & B43_DMA32_TXADDREXT_MASK)
                return B43_DMA_32BIT;
        return B43_DMA_30BIT;
}

/* Main initialization function. */
static
struct b43_dmaring *b43_setup_dmaring(struct b43_wldev *dev,
                                      int controller_index,
                                      int for_tx,
                                      enum b43_dmatype type)
{
        struct b43_dmaring *ring;
        int i, err;
        dma_addr_t dma_test;

        ring = kzalloc(sizeof(*ring), GFP_KERNEL);
        if (!ring)
                goto out;

        ring->nr_slots = B43_RXRING_SLOTS;
        if (for_tx)
                ring->nr_slots = B43_TXRING_SLOTS;

        ring->meta = kcalloc(ring->nr_slots, sizeof(struct b43_dmadesc_meta),
                             GFP_KERNEL);
        if (!ring->meta)
                goto err_kfree_ring;
        for (i = 0; i < ring->nr_slots; i++)
                ring->meta->skb = B43_DMA_PTR_POISON;

        ring->type = type;
        ring->dev = dev;
        ring->mmio_base = b43_dmacontroller_base(type, controller_index);
        ring->index = controller_index;
        if (type == B43_DMA_64BIT)
                ring->ops = &dma64_ops;
        else
                ring->ops = &dma32_ops;
        if (for_tx) {
                ring->tx = true;
                ring->current_slot = -1;
        } else {
                if (ring->index == 0) {
                        switch (dev->fw.hdr_format) {
                        case B43_FW_HDR_598:
                                ring->rx_buffersize = B43_DMA0_RX_FW598_BUFSIZE;
                                ring->frameoffset = B43_DMA0_RX_FW598_FO;
                                break;
                        case B43_FW_HDR_410:
                        case B43_FW_HDR_351:
                                ring->rx_buffersize = B43_DMA0_RX_FW351_BUFSIZE;
                                ring->frameoffset = B43_DMA0_RX_FW351_FO;
                                break;
                        }
                } else
                        B43_WARN_ON(1);
        }
#ifdef CONFIG_B43_DEBUG
        ring->last_injected_overflow = jiffies;
#endif

        if (for_tx) {
                /* Assumption: B43_TXRING_SLOTS can be divided by TX_SLOTS_PER_FRAME */
                BUILD_BUG_ON(B43_TXRING_SLOTS % TX_SLOTS_PER_FRAME != 0);

                ring->txhdr_cache = kcalloc(ring->nr_slots / TX_SLOTS_PER_FRAME,
                                            b43_txhdr_size(dev),
                                            GFP_KERNEL);
                if (!ring->txhdr_cache)
                        goto err_kfree_meta;

                /* test for ability to dma to txhdr_cache */
                dma_test = dma_map_single(dev->dev->dma_dev,
                                          ring->txhdr_cache,
                                          b43_txhdr_size(dev),
                                          DMA_TO_DEVICE);

                if (b43_dma_mapping_error(ring, dma_test,
                                          b43_txhdr_size(dev), 1)) {
                        /* ugh realloc */
                        kfree(ring->txhdr_cache);
                        ring->txhdr_cache = kcalloc(ring->nr_slots / TX_SLOTS_PER_FRAME,
                                                    b43_txhdr_size(dev),
                                                    GFP_KERNEL | GFP_DMA);
                        if (!ring->txhdr_cache)
                                goto err_kfree_meta;

                        dma_test = dma_map_single(dev->dev->dma_dev,
                                                  ring->txhdr_cache,
                                                  b43_txhdr_size(dev),
                                                  DMA_TO_DEVICE);

                        if (b43_dma_mapping_error(ring, dma_test,
                                                  b43_txhdr_size(dev), 1)) {

                                b43err(dev->wl,
                                       "TXHDR DMA allocation failed\n");
                                goto err_kfree_txhdr_cache;
                        }
                }

                dma_unmap_single(dev->dev->dma_dev,
                                 dma_test, b43_txhdr_size(dev),
                                 DMA_TO_DEVICE);
        }

        err = alloc_ringmemory(ring);
        if (err)
                goto err_kfree_txhdr_cache;
        err = dmacontroller_setup(ring);
        if (err)
                goto err_free_ringmemory;

      out:
        return ring;

      err_free_ringmemory:
        free_ringmemory(ring);
      err_kfree_txhdr_cache:
        kfree(ring->txhdr_cache);
      err_kfree_meta:
        kfree(ring->meta);
      err_kfree_ring:
        kfree(ring);
        ring = NULL;
        goto out;
}

#define divide(a, b)    ({      \
        typeof(a) __a = a;      \
        do_div(__a, b);         \
        __a;                    \
  })

#define modulo(a, b)    ({      \
        typeof(a) __a = a;      \
        do_div(__a, b);         \
  })

/* Main cleanup function. */
static void b43_destroy_dmaring(struct b43_dmaring *ring,
                                const char *ringname)
{
        if (!ring)
                return;

#ifdef CONFIG_B43_DEBUG
        {
                /* Print some statistics. */
                u64 failed_packets = ring->nr_failed_tx_packets;
                u64 succeed_packets = ring->nr_succeed_tx_packets;
                u64 nr_packets = failed_packets + succeed_packets;
                u64 permille_failed = 0, average_tries = 0;

                if (nr_packets)
                        permille_failed = divide(failed_packets * 1000, nr_packets);
                if (nr_packets)
                        average_tries = divide(ring->nr_total_packet_tries * 100, nr_packets);

                b43dbg(ring->dev->wl, "DMA-%u %s: "
                       "Used slots %d/%d, Failed frames %llu/%llu = %llu.%01llu%%, "
                       "Average tries %llu.%02llu\n",
                       (unsigned int)(ring->type), ringname,
                       ring->max_used_slots,
                       ring->nr_slots,
                       (unsigned long long)failed_packets,
                       (unsigned long long)nr_packets,
                       (unsigned long long)divide(permille_failed, 10),
                       (unsigned long long)modulo(permille_failed, 10),
                       (unsigned long long)divide(average_tries, 100),
                       (unsigned long long)modulo(average_tries, 100));
        }
#endif /* DEBUG */

        /* Device IRQs are disabled prior entering this function,

         * so no need to take care of concurrency with rx handler stuff.
         */
        dmacontroller_cleanup(ring);
        free_all_descbuffers(ring);
        free_ringmemory(ring);

        kfree(ring->txhdr_cache);
        kfree(ring->meta);
        kfree(ring);
}

#define destroy_ring(dma, ring) do {                            \
        b43_destroy_dmaring((dma)->ring, __stringify(ring));    \
        (dma)->ring = NULL;                                     \
    } while (0)

void b43_dma_free(struct b43_wldev *dev)
{
        struct b43_dma *dma;

        if (b43_using_pio_transfers(dev))
                return;
        dma = &dev->dma;

        destroy_ring(dma, rx_ring);
        destroy_ring(dma, tx_ring_AC_BK);
        destroy_ring(dma, tx_ring_AC_BE);
        destroy_ring(dma, tx_ring_AC_VI);
        destroy_ring(dma, tx_ring_AC_VO);
        destroy_ring(dma, tx_ring_mcast);
}

/* Some hardware with 64-bit DMA seems to be bugged and looks for translation
 * bit in low address word instead of high one.
 */
static bool b43_dma_translation_in_low_word(struct b43_wldev *dev,
                                            enum b43_dmatype type)
{
        if (type != B43_DMA_64BIT)
                return true;

#ifdef CONFIG_B43_SSB
        if (dev->dev->bus_type == B43_BUS_SSB &&
            dev->dev->sdev->bus->bustype == SSB_BUSTYPE_PCI &&
            !(pci_is_pcie(dev->dev->sdev->bus->host_pci) &&
              ssb_read32(dev->dev->sdev, SSB_TMSHIGH) & SSB_TMSHIGH_DMA64))
                        return true;
#endif
        return false;
}

int b43_dma_init(struct b43_wldev *dev)
{
        struct b43_dma *dma = &dev->dma;
        enum b43_dmatype type = b43_engine_type(dev);
        int err;

        err = dma_set_mask_and_coherent(dev->dev->dma_dev, DMA_BIT_MASK(type));
        if (err) {
                b43err(dev->wl, "The machine/kernel does not support "
                       "the required %u-bit DMA mask\n", type);
                return err;
        }

        switch (dev->dev->bus_type) {
#ifdef CONFIG_B43_BCMA
        case B43_BUS_BCMA:
                dma->translation = bcma_core_dma_translation(dev->dev->bdev);
                break;
#endif
#ifdef CONFIG_B43_SSB
        case B43_BUS_SSB:
                dma->translation = ssb_dma_translation(dev->dev->sdev);
                break;
#endif
        }
        dma->translation_in_low = b43_dma_translation_in_low_word(dev, type);

        dma->parity = true;
#ifdef CONFIG_B43_BCMA
        /* TODO: find out which SSB devices need disabling parity */
        if (dev->dev->bus_type == B43_BUS_BCMA)
                dma->parity = false;
#endif

        err = -ENOMEM;
        /* setup TX DMA channels. */
        dma->tx_ring_AC_BK = b43_setup_dmaring(dev, 0, 1, type);
        if (!dma->tx_ring_AC_BK)
                goto out;

        dma->tx_ring_AC_BE = b43_setup_dmaring(dev, 1, 1, type);
        if (!dma->tx_ring_AC_BE)
                goto err_destroy_bk;

        dma->tx_ring_AC_VI = b43_setup_dmaring(dev, 2, 1, type);
        if (!dma->tx_ring_AC_VI)
                goto err_destroy_be;

        dma->tx_ring_AC_VO = b43_setup_dmaring(dev, 3, 1, type);
        if (!dma->tx_ring_AC_VO)
                goto err_destroy_vi;

        dma->tx_ring_mcast = b43_setup_dmaring(dev, 4, 1, type);
        if (!dma->tx_ring_mcast)
                goto err_destroy_vo;

        /* setup RX DMA channel. */
        dma->rx_ring = b43_setup_dmaring(dev, 0, 0, type);
        if (!dma->rx_ring)
                goto err_destroy_mcast;

        /* No support for the TX status DMA ring. */
        B43_WARN_ON(dev->dev->core_rev < 5);

        b43dbg(dev->wl, "%u-bit DMA initialized\n",
               (unsigned int)type);
        err = 0;
out:
        return err;

err_destroy_mcast:
        destroy_ring(dma, tx_ring_mcast);
err_destroy_vo:
        destroy_ring(dma, tx_ring_AC_VO);
err_destroy_vi:
        destroy_ring(dma, tx_ring_AC_VI);
err_destroy_be:
        destroy_ring(dma, tx_ring_AC_BE);
err_destroy_bk:
        destroy_ring(dma, tx_ring_AC_BK);
        return err;
}

/* Generate a cookie for the TX header. */
static u16 generate_cookie(struct b43_dmaring *ring, int slot)
{
        u16 cookie;

        /* Use the upper 4 bits of the cookie as
         * DMA controller ID and store the slot 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)ring->index + 1) << 12);
        B43_WARN_ON(slot & ~0x0FFF);
        cookie |= (u16)slot;

        return cookie;
}

/* Inspect a cookie and find out to which controller/slot it belongs. */
static
struct b43_dmaring *parse_cookie(struct b43_wldev *dev, u16 cookie, int *slot)
{
        struct b43_dma *dma = &dev->dma;
        struct b43_dmaring *ring = NULL;

        switch (cookie & 0xF000) {
        case 0x1000:
                ring = dma->tx_ring_AC_BK;
                break;
        case 0x2000:
                ring = dma->tx_ring_AC_BE;
                break;
        case 0x3000:
                ring = dma->tx_ring_AC_VI;
                break;
        case 0x4000:
                ring = dma->tx_ring_AC_VO;
                break;
        case 0x5000:
                ring = dma->tx_ring_mcast;
                break;
        }
        *slot = (cookie & 0x0FFF);
        if (unlikely(!ring || *slot < 0 || *slot >= ring->nr_slots)) {
                b43dbg(dev->wl, "TX-status contains "
                       "invalid cookie: 0x%04X\n", cookie);
                return NULL;
        }

        return ring;
}

static int dma_tx_fragment(struct b43_dmaring *ring,
                           struct sk_buff *skb)
{
        const struct b43_dma_ops *ops = ring->ops;
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
        struct b43_private_tx_info *priv_info = b43_get_priv_tx_info(info);
        u8 *header;
        int slot, old_top_slot, old_used_slots;
        int err;
        struct b43_dmadesc_generic *desc;
        struct b43_dmadesc_meta *meta;
        struct b43_dmadesc_meta *meta_hdr;
        u16 cookie;
        size_t hdrsize = b43_txhdr_size(ring->dev);

        /* Important note: If the number of used DMA slots per TX frame
         * is changed here, the TX_SLOTS_PER_FRAME definition at the top of
         * the file has to be updated, too!
         */

        old_top_slot = ring->current_slot;
        old_used_slots = ring->used_slots;

        /* Get a slot for the header. */
        slot = request_slot(ring);
        desc = ops->idx2desc(ring, slot, &meta_hdr);
        memset(meta_hdr, 0, sizeof(*meta_hdr));

        header = &(ring->txhdr_cache[(slot / TX_SLOTS_PER_FRAME) * hdrsize]);
        cookie = generate_cookie(ring, slot);
        err = b43_generate_txhdr(ring->dev, header,
                                 skb, info, cookie);
        if (unlikely(err)) {
                ring->current_slot = old_top_slot;
                ring->used_slots = old_used_slots;
                return err;
        }

        meta_hdr->dmaaddr = map_descbuffer(ring, (unsigned char *)header,
                                           hdrsize, 1);
        if (b43_dma_mapping_error(ring, meta_hdr->dmaaddr, hdrsize, 1)) {
                ring->current_slot = old_top_slot;
                ring->used_slots = old_used_slots;
                return -EIO;
        }
        ops->fill_descriptor(ring, desc, meta_hdr->dmaaddr,
                             hdrsize, 1, 0, 0);

        /* Get a slot for the payload. */
        slot = request_slot(ring);
        desc = ops->idx2desc(ring, slot, &meta);
        memset(meta, 0, sizeof(*meta));

        meta->skb = skb;
        meta->is_last_fragment = true;
        priv_info->bouncebuffer = NULL;

        meta->dmaaddr = map_descbuffer(ring, skb->data, skb->len, 1);
        /* create a bounce buffer in zone_dma on mapping failure. */
        if (b43_dma_mapping_error(ring, meta->dmaaddr, skb->len, 1)) {
                priv_info->bouncebuffer = kmemdup(skb->data, skb->len,
                                                  GFP_ATOMIC | GFP_DMA);
                if (!priv_info->bouncebuffer) {
                        ring->current_slot = old_top_slot;
                        ring->used_slots = old_used_slots;
                        err = -ENOMEM;
                        goto out_unmap_hdr;
                }

                meta->dmaaddr = map_descbuffer(ring, priv_info->bouncebuffer, skb->len, 1);
                if (b43_dma_mapping_error(ring, meta->dmaaddr, skb->len, 1)) {
                        kfree(priv_info->bouncebuffer);
                        priv_info->bouncebuffer = NULL;
                        ring->current_slot = old_top_slot;
                        ring->used_slots = old_used_slots;
                        err = -EIO;
                        goto out_unmap_hdr;
                }
        }

        ops->fill_descriptor(ring, desc, meta->dmaaddr, skb->len, 0, 1, 1);

        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(ring->dev, B43_SHM_SHARED,
                                B43_SHM_SH_MCASTCOOKIE, cookie);
        }
        /* Now transfer the whole frame. */
        wmb();
        ops->poke_tx(ring, next_slot(ring, slot));
        return 0;

out_unmap_hdr:
        unmap_descbuffer(ring, meta_hdr->dmaaddr,
                         hdrsize, 1);
        return err;
}

static inline int should_inject_overflow(struct b43_dmaring *ring)
{
#ifdef CONFIG_B43_DEBUG
        if (unlikely(b43_debug(ring->dev, B43_DBG_DMAOVERFLOW))) {
                /* Check if we should inject another ringbuffer overflow
                 * to test handling of this situation in the stack. */
                unsigned long next_overflow;

                next_overflow = ring->last_injected_overflow + HZ;
                if (time_after(jiffies, next_overflow)) {
                        ring->last_injected_overflow = jiffies;
                        b43dbg(ring->dev->wl,
                               "Injecting TX ring overflow on "
                               "DMA controller %d\n", ring->index);
                        return 1;
                }
        }
#endif /* CONFIG_B43_DEBUG */
        return 0;
}

/* Static mapping of mac80211's queues (priorities) to b43 DMA rings. */
static struct b43_dmaring *select_ring_by_priority(struct b43_wldev *dev,
                                                   u8 queue_prio)
{
        struct b43_dmaring *ring;

        if (dev->qos_enabled) {
                /* 0 = highest priority */
                switch (queue_prio) {
                default:
                        B43_WARN_ON(1);
                        /* fallthrough */
                case 0:
                        ring = dev->dma.tx_ring_AC_VO;
                        break;
                case 1:
                        ring = dev->dma.tx_ring_AC_VI;
                        break;
                case 2:
                        ring = dev->dma.tx_ring_AC_BE;
                        break;
                case 3:
                        ring = dev->dma.tx_ring_AC_BK;
                        break;
                }
        } else
                ring = dev->dma.tx_ring_AC_BE;

        return ring;
}

int b43_dma_tx(struct b43_wldev *dev, struct sk_buff *skb)
{
        struct b43_dmaring *ring;
        struct ieee80211_hdr *hdr;
        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 ring will be sent after the DTIM */
                ring = dev->dma.tx_ring_mcast;
                /* Set the more-data bit. Ucode will clear it on
                 * the last frame for us. */
                hdr->frame_control |= cpu_to_le16(IEEE80211_FCTL_MOREDATA);
        } else {
                /* Decide by priority where to put this frame. */
                ring = select_ring_by_priority(
                        dev, skb_get_queue_mapping(skb));
        }

        B43_WARN_ON(!ring->tx);

        if (unlikely(ring->stopped)) {
                /* We get here only because of a bug in mac80211.
                 * Because of a race, one packet may be queued after
                 * the queue is stopped, thus we got called when we shouldn't.
                 * For now, just refuse the transmit. */
                if (b43_debug(dev, B43_DBG_DMAVERBOSE))
                        b43err(dev->wl, "Packet after queue stopped\n");
                err = -ENOSPC;
                goto out;
        }

        if (WARN_ON(free_slots(ring) < TX_SLOTS_PER_FRAME)) {
                /* If we get here, we have a real error with the queue
                 * full, but queues not stopped. */
                b43err(dev->wl, "DMA queue overflow\n");
                err = -ENOSPC;
                goto out;
        }

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

        err = dma_tx_fragment(ring, skb);
        if (unlikely(err == -ENOKEY)) {
                /* Drop this packet, as we don't have the encryption key
                 * anymore and must not transmit it unencrypted. */
                ieee80211_free_txskb(dev->wl->hw, skb);
                err = 0;
                goto out;
        }
        if (unlikely(err)) {
                b43err(dev->wl, "DMA tx mapping failure\n");
                goto out;
        }
        if ((free_slots(ring) < TX_SLOTS_PER_FRAME) ||
            should_inject_overflow(ring)) {
                /* This TX ring is full. */
                unsigned int skb_mapping = skb_get_queue_mapping(skb);
                ieee80211_stop_queue(dev->wl->hw, skb_mapping);
                dev->wl->tx_queue_stopped[skb_mapping] = 1;
                ring->stopped = true;
                if (b43_debug(dev, B43_DBG_DMAVERBOSE)) {
                        b43dbg(dev->wl, "Stopped TX ring %d\n", ring->index);
                }
        }
out:

        return err;
}

void b43_dma_handle_txstatus(struct b43_wldev *dev,
                             const struct b43_txstatus *status)
{
        const struct b43_dma_ops *ops;
        struct b43_dmaring *ring;
        struct b43_dmadesc_meta *meta;
        static const struct b43_txstatus fake; /* filled with 0 */
        const struct b43_txstatus *txstat;
        int slot, firstused;
        bool frame_succeed;
        int skip;
        static u8 err_out1;

        ring = parse_cookie(dev, status->cookie, &slot);
        if (unlikely(!ring))
                return;
        B43_WARN_ON(!ring->tx);

        /* Sanity check: TX packets are processed in-order on one ring.
         * Check if the slot deduced from the cookie really is the first
         * used slot. */
        firstused = ring->current_slot - ring->used_slots + 1;
        if (firstused < 0)
                firstused = ring->nr_slots + firstused;

        skip = 0;
        if (unlikely(slot != firstused)) {
                /* This possibly is a firmware bug and will result in
                 * malfunction, memory leaks and/or stall of DMA functionality.
                 */
                if (slot == next_slot(ring, next_slot(ring, firstused))) {
                        /* If a single header/data pair was missed, skip over
                         * the first two slots in an attempt to recover.
                         */
                        slot = firstused;
                        skip = 2;
                        if (!err_out1) {
                                /* Report the error once. */
                                b43dbg(dev->wl,
                                       "Skip on DMA ring %d slot %d.\n",
                                       ring->index, slot);
                                err_out1 = 1;
                        }
                } else {
                        /* More than a single header/data pair were missed.
                         * Report this error. If running with open-source
                         * firmware, then reset the controller to
                         * revive operation.
                         */
                        b43dbg(dev->wl,
                               "Out of order TX status report on DMA ring %d. Expected %d, but got %d\n",
                               ring->index, firstused, slot);
                        if (dev->fw.opensource)
                                b43_controller_restart(dev, "Out of order TX");
                        return;
                }
        }

        ops = ring->ops;
        while (1) {
                B43_WARN_ON(slot < 0 || slot >= ring->nr_slots);
                /* get meta - ignore returned value */
                ops->idx2desc(ring, slot, &meta);

                if (b43_dma_ptr_is_poisoned(meta->skb)) {
                        b43dbg(dev->wl, "Poisoned TX slot %d (first=%d) "
                               "on ring %d\n",
                               slot, firstused, ring->index);
                        break;
                }

                if (meta->skb) {
                        struct b43_private_tx_info *priv_info =
                             b43_get_priv_tx_info(IEEE80211_SKB_CB(meta->skb));

                        unmap_descbuffer(ring, meta->dmaaddr,
                                         meta->skb->len, 1);
                        kfree(priv_info->bouncebuffer);
                        priv_info->bouncebuffer = NULL;
                } else {
                        unmap_descbuffer(ring, meta->dmaaddr,
                                         b43_txhdr_size(dev), 1);
                }

                if (meta->is_last_fragment) {
                        struct ieee80211_tx_info *info;

                        if (unlikely(!meta->skb)) {
                                /* This is a scatter-gather fragment of a frame,
                                 * so the skb pointer must not be NULL.
                                 */
                                b43dbg(dev->wl, "TX status unexpected NULL skb "
                                       "at slot %d (first=%d) on ring %d\n",
                                       slot, firstused, ring->index);
                                break;
                        }

                        info = IEEE80211_SKB_CB(meta->skb);

                        /*
                         * Call back to inform the ieee80211 subsystem about
                         * the status of the transmission. When skipping over
                         * a missed TX status report, use a status structure
                         * filled with zeros to indicate that the frame was not
                         * sent (frame_count 0) and not acknowledged
                         */
                        if (unlikely(skip))
                                txstat = &fake;
                        else
                                txstat = status;

                        frame_succeed = b43_fill_txstatus_report(dev, info,
                                                                 txstat);
#ifdef CONFIG_B43_DEBUG
                        if (frame_succeed)
                                ring->nr_succeed_tx_packets++;
                        else
                                ring->nr_failed_tx_packets++;
                        ring->nr_total_packet_tries += status->frame_count;
#endif /* DEBUG */
                        ieee80211_tx_status(dev->wl->hw, meta->skb);

                        /* skb will be freed by ieee80211_tx_status().
                         * Poison our pointer. */
                        meta->skb = B43_DMA_PTR_POISON;
                } else {
                        /* No need to call free_descriptor_buffer here, as
                         * this is only the txhdr, which is not allocated.
                         */
                        if (unlikely(meta->skb)) {
                                b43dbg(dev->wl, "TX status unexpected non-NULL skb "
                                       "at slot %d (first=%d) on ring %d\n",
                                       slot, firstused, ring->index);
                                break;
                        }
                }

                /* Everything unmapped and free'd. So it's not used anymore. */
                ring->used_slots--;

                if (meta->is_last_fragment && !skip) {
                        /* This is the last scatter-gather
                         * fragment of the frame. We are done. */
                        break;
                }
                slot = next_slot(ring, slot);
                if (skip > 0)
                        --skip;
        }
        if (ring->stopped) {
                B43_WARN_ON(free_slots(ring) < TX_SLOTS_PER_FRAME);
                ring->stopped = false;
        }

        if (dev->wl->tx_queue_stopped[ring->queue_prio]) {
                dev->wl->tx_queue_stopped[ring->queue_prio] = 0;
        } else {
                /* If the driver queue is running wake the corresponding
                 * mac80211 queue. */
                ieee80211_wake_queue(dev->wl->hw, ring->queue_prio);
                if (b43_debug(dev, B43_DBG_DMAVERBOSE)) {
                        b43dbg(dev->wl, "Woke up TX ring %d\n", ring->index);
                }
        }
        /* Add work to the queue. */
        ieee80211_queue_work(dev->wl->hw, &dev->wl->tx_work);
}

static void dma_rx(struct b43_dmaring *ring, int *slot)
{
        const struct b43_dma_ops *ops = ring->ops;
        struct b43_dmadesc_generic *desc;
        struct b43_dmadesc_meta *meta;
        struct b43_rxhdr_fw4 *rxhdr;
        struct sk_buff *skb;
        u16 len;
        int err;
        dma_addr_t dmaaddr;

        desc = ops->idx2desc(ring, *slot, &meta);

        sync_descbuffer_for_cpu(ring, meta->dmaaddr, ring->rx_buffersize);
        skb = meta->skb;

        rxhdr = (struct b43_rxhdr_fw4 *)skb->data;
        len = le16_to_cpu(rxhdr->frame_len);
        if (len == 0) {
                int i = 0;

                do {
                        udelay(2);
                        barrier();
                        len = le16_to_cpu(rxhdr->frame_len);
                } while (len == 0 && i++ < 5);
                if (unlikely(len == 0)) {
                        dmaaddr = meta->dmaaddr;
                        goto drop_recycle_buffer;
                }
        }
        if (unlikely(b43_rx_buffer_is_poisoned(ring, skb))) {
                /* Something went wrong with the DMA.
                 * The device did not touch the buffer and did not overwrite the poison. */
                b43dbg(ring->dev->wl, "DMA RX: Dropping poisoned buffer.\n");
                dmaaddr = meta->dmaaddr;
                goto drop_recycle_buffer;
        }
        if (unlikely(len + ring->frameoffset > ring->rx_buffersize)) {
                /* The data did not fit into one descriptor buffer
                 * and is split over multiple buffers.
                 * This should never happen, as we try to allocate buffers
                 * big enough. So simply ignore this packet.
                 */
                int cnt = 0;
                s32 tmp = len;

                while (1) {
                        desc = ops->idx2desc(ring, *slot, &meta);
                        /* recycle the descriptor buffer. */
                        b43_poison_rx_buffer(ring, meta->skb);
                        sync_descbuffer_for_device(ring, meta->dmaaddr,
                                                   ring->rx_buffersize);
                        *slot = next_slot(ring, *slot);
                        cnt++;
                        tmp -= ring->rx_buffersize;
                        if (tmp <= 0)
                                break;
                }
                b43err(ring->dev->wl, "DMA RX buffer too small "
                       "(len: %u, buffer: %u, nr-dropped: %d)\n",
                       len, ring->rx_buffersize, cnt);
                goto drop;
        }

        dmaaddr = meta->dmaaddr;
        err = setup_rx_descbuffer(ring, desc, meta, GFP_ATOMIC);
        if (unlikely(err)) {
                b43dbg(ring->dev->wl, "DMA RX: setup_rx_descbuffer() failed\n");
                goto drop_recycle_buffer;
        }

        unmap_descbuffer(ring, dmaaddr, ring->rx_buffersize, 0);
        skb_put(skb, len + ring->frameoffset);
        skb_pull(skb, ring->frameoffset);

        b43_rx(ring->dev, skb, rxhdr);
drop:
        return;

drop_recycle_buffer:
        /* Poison and recycle the RX buffer. */
        b43_poison_rx_buffer(ring, skb);
        sync_descbuffer_for_device(ring, dmaaddr, ring->rx_buffersize);
}

void b43_dma_handle_rx_overflow(struct b43_dmaring *ring)
{
        int current_slot, previous_slot;

        B43_WARN_ON(ring->tx);

        /* Device has filled all buffers, drop all packets and let TCP
         * decrease speed.
         * Decrement RX index by one will let the device to see all slots
         * as free again
         */
        /*
        *TODO: How to increase rx_drop in mac80211?
        */
        current_slot = ring->ops->get_current_rxslot(ring);
        previous_slot = prev_slot(ring, current_slot);
        ring->ops->set_current_rxslot(ring, previous_slot);
}

void b43_dma_rx(struct b43_dmaring *ring)
{
        const struct b43_dma_ops *ops = ring->ops;
        int slot, current_slot;
        int used_slots = 0;

        B43_WARN_ON(ring->tx);
        current_slot = ops->get_current_rxslot(ring);
        B43_WARN_ON(!(current_slot >= 0 && current_slot < ring->nr_slots));

        slot = ring->current_slot;
        for (; slot != current_slot; slot = next_slot(ring, slot)) {
                dma_rx(ring, &slot);
                update_max_used_slots(ring, ++used_slots);
        }
        wmb();
        ops->set_current_rxslot(ring, slot);
        ring->current_slot = slot;
}

static void b43_dma_tx_suspend_ring(struct b43_dmaring *ring)
{
        B43_WARN_ON(!ring->tx);
        ring->ops->tx_suspend(ring);
}

static void b43_dma_tx_resume_ring(struct b43_dmaring *ring)
{
        B43_WARN_ON(!ring->tx);
        ring->ops->tx_resume(ring);
}

void b43_dma_tx_suspend(struct b43_wldev *dev)
{
        b43_power_saving_ctl_bits(dev, B43_PS_AWAKE);
        b43_dma_tx_suspend_ring(dev->dma.tx_ring_AC_BK);
        b43_dma_tx_suspend_ring(dev->dma.tx_ring_AC_BE);
        b43_dma_tx_suspend_ring(dev->dma.tx_ring_AC_VI);
        b43_dma_tx_suspend_ring(dev->dma.tx_ring_AC_VO);
        b43_dma_tx_suspend_ring(dev->dma.tx_ring_mcast);
}

void b43_dma_tx_resume(struct b43_wldev *dev)
{
        b43_dma_tx_resume_ring(dev->dma.tx_ring_mcast);
        b43_dma_tx_resume_ring(dev->dma.tx_ring_AC_VO);
        b43_dma_tx_resume_ring(dev->dma.tx_ring_AC_VI);
        b43_dma_tx_resume_ring(dev->dma.tx_ring_AC_BE);
        b43_dma_tx_resume_ring(dev->dma.tx_ring_AC_BK);
        b43_power_saving_ctl_bits(dev, 0);
}

static void direct_fifo_rx(struct b43_wldev *dev, enum b43_dmatype type,
                           u16 mmio_base, bool enable)
{
        u32 ctl;

        if (type == B43_DMA_64BIT) {
                ctl = b43_read32(dev, mmio_base + B43_DMA64_RXCTL);
                ctl &= ~B43_DMA64_RXDIRECTFIFO;
                if (enable)
                        ctl |= B43_DMA64_RXDIRECTFIFO;
                b43_write32(dev, mmio_base + B43_DMA64_RXCTL, ctl);
        } else {
                ctl = b43_read32(dev, mmio_base + B43_DMA32_RXCTL);
                ctl &= ~B43_DMA32_RXDIRECTFIFO;
                if (enable)
                        ctl |= B43_DMA32_RXDIRECTFIFO;
                b43_write32(dev, mmio_base + B43_DMA32_RXCTL, ctl);
        }
}

/* Enable/Disable Direct FIFO Receive Mode (PIO) on a RX engine.
 * This is called from PIO code, so DMA structures are not available. */
void b43_dma_direct_fifo_rx(struct b43_wldev *dev,
                            unsigned int engine_index, bool enable)
{
        enum b43_dmatype type;
        u16 mmio_base;

        type = b43_engine_type(dev);

        mmio_base = b43_dmacontroller_base(type, engine_index);
        direct_fifo_rx(dev, type, mmio_base, enable);
}