dma.c

linux内核源码

	err = 0;
out:
	return err;

err_destroy_rx0:
	b43legacy_destroy_dmaring(dma->rx_ring0);
	dma->rx_ring0 = NULL;
err_destroy_tx5:
	b43legacy_destroy_dmaring(dma->tx_ring5);
	dma->tx_ring5 = NULL;
err_destroy_tx4:
	b43legacy_destroy_dmaring(dma->tx_ring4);
	dma->tx_ring4 = NULL;
err_destroy_tx3:
	b43legacy_destroy_dmaring(dma->tx_ring3);
	dma->tx_ring3 = NULL;
err_destroy_tx2:
	b43legacy_destroy_dmaring(dma->tx_ring2);
	dma->tx_ring2 = NULL;
err_destroy_tx1:
	b43legacy_destroy_dmaring(dma->tx_ring1);
	dma->tx_ring1 = NULL;
err_destroy_tx0:
	b43legacy_destroy_dmaring(dma->tx_ring0);
	dma->tx_ring0 = NULL;
	goto out;
}

/* Generate a cookie for the TX header. */
static u16 generate_cookie(struct b43legacy_dmaring *ring,
			   int slot)
{
	u16 cookie = 0x1000;

	/* 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.
	 */
	switch (ring->index) {
	case 0:
		cookie = 0xA000;
		break;
	case 1:
		cookie = 0xB000;
		break;
	case 2:
		cookie = 0xC000;
		break;
	case 3:
		cookie = 0xD000;
		break;
	case 4:
		cookie = 0xE000;
		break;
	case 5:
		cookie = 0xF000;
		break;
	}
	B43legacy_WARN_ON(!(((u16)slot & 0xF000) == 0x0000));
	cookie |= (u16)slot;

	return cookie;
}

/* Inspect a cookie and find out to which controller/slot it belongs. */
static
struct b43legacy_dmaring *parse_cookie(struct b43legacy_wldev *dev,
				      u16 cookie, int *slot)
{
	struct b43legacy_dma *dma = &dev->dma;
	struct b43legacy_dmaring *ring = NULL;

	switch (cookie & 0xF000) {
	case 0xA000:
		ring = dma->tx_ring0;
		break;
	case 0xB000:
		ring = dma->tx_ring1;
		break;
	case 0xC000:
		ring = dma->tx_ring2;
		break;
	case 0xD000:
		ring = dma->tx_ring3;
		break;
	case 0xE000:
		ring = dma->tx_ring4;
		break;
	case 0xF000:
		ring = dma->tx_ring5;
		break;
	default:
		B43legacy_WARN_ON(1);
	}
	*slot = (cookie & 0x0FFF);
	B43legacy_WARN_ON(!(ring && *slot >= 0 && *slot < ring->nr_slots));

	return ring;
}

static int dma_tx_fragment(struct b43legacy_dmaring *ring,
			    struct sk_buff *skb,
			    struct ieee80211_tx_control *ctl)
{
	const struct b43legacy_dma_ops *ops = ring->ops;
	u8 *header;
	int slot, old_top_slot, old_used_slots;
	int err;
	struct b43legacy_dmadesc_generic *desc;
	struct b43legacy_dmadesc_meta *meta;
	struct b43legacy_dmadesc_meta *meta_hdr;
	struct sk_buff *bounce_skb;

#define SLOTS_PER_PACKET  2
	B43legacy_WARN_ON(skb_shinfo(skb)->nr_frags != 0);

	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 * sizeof(
			       struct b43legacy_txhdr_fw3)]);
	err = b43legacy_generate_txhdr(ring->dev, header,
				 skb->data, skb->len, ctl,
				 generate_cookie(ring, slot));
	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,
				       sizeof(struct b43legacy_txhdr_fw3), 1);
	if (dma_mapping_error(meta_hdr->dmaaddr))
		return -EIO;
	ops->fill_descriptor(ring, desc, meta_hdr->dmaaddr,
			     sizeof(struct b43legacy_txhdr_fw3), 1, 0, 0);

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

	memcpy(&meta->txstat.control, ctl, sizeof(*ctl));
	meta->skb = skb;
	meta->is_last_fragment = 1;

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

		memcpy(skb_put(bounce_skb, skb->len), skb->data, skb->len);
		dev_kfree_skb_any(skb);
		skb = bounce_skb;
		meta->skb = skb;
		meta->dmaaddr = map_descbuffer(ring, skb->data, skb->len, 1);
		if (dma_mapping_error(meta->dmaaddr)) {
			ring->current_slot = old_top_slot;
			ring->used_slots = old_used_slots;
			err = -EIO;
			goto out_free_bounce;
		}
	}

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

	wmb();	/* previous stuff MUST be done */
	/* Now transfer the whole frame. */
	ops->poke_tx(ring, next_slot(ring, slot));
	return 0;

out_free_bounce:
	dev_kfree_skb_any(skb);
out_unmap_hdr:
	unmap_descbuffer(ring, meta_hdr->dmaaddr,
			 sizeof(struct b43legacy_txhdr_fw3), 1);
	return err;
}

static inline
int should_inject_overflow(struct b43legacy_dmaring *ring)
{
#ifdef CONFIG_B43LEGACY_DEBUG
	if (unlikely(b43legacy_debug(ring->dev,
				     B43legacy_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;
			b43legacydbg(ring->dev->wl,
			       "Injecting TX ring overflow on "
			       "DMA controller %d\n", ring->index);
			return 1;
		}
	}
#endif /* CONFIG_B43LEGACY_DEBUG */
	return 0;
}

int b43legacy_dma_tx(struct b43legacy_wldev *dev,
		     struct sk_buff *skb,
		     struct ieee80211_tx_control *ctl)
{
	struct b43legacy_dmaring *ring;
	int err = 0;
	unsigned long flags;

	ring = priority_to_txring(dev, ctl->queue);
	spin_lock_irqsave(&ring->lock, flags);
	B43legacy_WARN_ON(!ring->tx);
	if (unlikely(free_slots(ring) < SLOTS_PER_PACKET)) {
		b43legacywarn(dev->wl, "DMA queue overflow\n");
		err = -ENOSPC;
		goto out_unlock;
	}
	/* Check if the queue was stopped in mac80211,
	 * but we got called nevertheless.
	 * That would be a mac80211 bug. */
	B43legacy_BUG_ON(ring->stopped);

	err = dma_tx_fragment(ring, skb, ctl);
	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_unlock;
	}
	if (unlikely(err)) {
		b43legacyerr(dev->wl, "DMA tx mapping failure\n");
		goto out_unlock;
	}
	ring->nr_tx_packets++;
	if ((free_slots(ring) < SLOTS_PER_PACKET) ||
	    should_inject_overflow(ring)) {
		/* This TX ring is full. */
		ieee80211_stop_queue(dev->wl->hw, txring_to_priority(ring));
		ring->stopped = 1;
		if (b43legacy_debug(dev, B43legacy_DBG_DMAVERBOSE))
			b43legacydbg(dev->wl, "Stopped TX ring %d\n",
			       ring->index);
	}
out_unlock:
	spin_unlock_irqrestore(&ring->lock, flags);

	return err;
}

void b43legacy_dma_handle_txstatus(struct b43legacy_wldev *dev,
				 const struct b43legacy_txstatus *status)
{
	const struct b43legacy_dma_ops *ops;
	struct b43legacy_dmaring *ring;
	struct b43legacy_dmadesc_generic *desc;
	struct b43legacy_dmadesc_meta *meta;
	int slot;

	ring = parse_cookie(dev, status->cookie, &slot);
	if (unlikely(!ring))
		return;
	B43legacy_WARN_ON(!irqs_disabled());
	spin_lock(&ring->lock);

	B43legacy_WARN_ON(!ring->tx);
	ops = ring->ops;
	while (1) {
		B43legacy_WARN_ON(!(slot >= 0 && slot < ring->nr_slots));
		desc = ops->idx2desc(ring, slot, &meta);

		if (meta->skb)
			unmap_descbuffer(ring, meta->dmaaddr,
					 meta->skb->len, 1);
		else
			unmap_descbuffer(ring, meta->dmaaddr,
					 sizeof(struct b43legacy_txhdr_fw3),
					 1);

		if (meta->is_last_fragment) {
			B43legacy_WARN_ON(!meta->skb);
			/* Call back to inform the ieee80211 subsystem about the
			 * status of the transmission.
			 * Some fields of txstat are already filled in dma_tx().
			 */
			if (status->acked) {
				meta->txstat.flags |= IEEE80211_TX_STATUS_ACK;
			} else {
				if (!(meta->txstat.control.flags
				      & IEEE80211_TXCTL_NO_ACK))
					 meta->txstat.excessive_retries = 1;
			}
			if (status->frame_count == 0) {
				/* The frame was not transmitted at all. */
				meta->txstat.retry_count = 0;
			} else
				meta->txstat.retry_count = status->frame_count
							   - 1;
			ieee80211_tx_status_irqsafe(dev->wl->hw, meta->skb,
						    &(meta->txstat));
			/* skb is freed by ieee80211_tx_status_irqsafe() */
			meta->skb = NULL;
		} else {
			/* No need to call free_descriptor_buffer here, as
			 * this is only the txhdr, which is not allocated.
			 */
			B43legacy_WARN_ON(meta->skb != NULL);
		}

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

		if (meta->is_last_fragment)
			break;
		slot = next_slot(ring, slot);
	}
	dev->stats.last_tx = jiffies;
	if (ring->stopped) {
		B43legacy_WARN_ON(free_slots(ring) < SLOTS_PER_PACKET);
		ieee80211_wake_queue(dev->wl->hw, txring_to_priority(ring));
		ring->stopped = 0;
		if (b43legacy_debug(dev, B43legacy_DBG_DMAVERBOSE))
			b43legacydbg(dev->wl, "Woke up TX ring %d\n",
			       ring->index);
	}

	spin_unlock(&ring->lock);
}

void b43legacy_dma_get_tx_stats(struct b43legacy_wldev *dev,
			      struct ieee80211_tx_queue_stats *stats)
{
	const int nr_queues = dev->wl->hw->queues;
	struct b43legacy_dmaring *ring;
	struct ieee80211_tx_queue_stats_data *data;
	unsigned long flags;
	int i;

	for (i = 0; i < nr_queues; i++) {
		data = &(stats->data[i]);
		ring = priority_to_txring(dev, i);

		spin_lock_irqsave(&ring->lock, flags);
		data->len = ring->used_slots / SLOTS_PER_PACKET;
		data->limit = ring->nr_slots / SLOTS_PER_PACKET;
		data->count = ring->nr_tx_packets;
		spin_unlock_irqrestore(&ring->lock, flags);
	}
}

static void dma_rx(struct b43legacy_dmaring *ring,
		   int *slot)
{
	const struct b43legacy_dma_ops *ops = ring->ops;
	struct b43legacy_dmadesc_generic *desc;
	struct b43legacy_dmadesc_meta *meta;
	struct b43legacy_rxhdr_fw3 *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;

	if (ring->index == 3) {
		/* We received an xmit status. */
		struct b43legacy_hwtxstatus *hw =
				(struct b43legacy_hwtxstatus *)skb->data;
		int i = 0;

		while (hw->cookie == 0) {
			if (i > 100)
				break;
			i++;
			udelay(2);
			barrier();
		}
		b43legacy_handle_hwtxstatus(ring->dev, hw);
		/* recycle the descriptor buffer. */
		sync_descbuffer_for_device(ring, meta->dmaaddr,
					   ring->rx_buffersize);

		return;
	}
	rxhdr = (struct b43legacy_rxhdr_fw3 *)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)) {
			/* recycle the descriptor buffer. */
			sync_descbuffer_for_device(ring, meta->dmaaddr,
						   ring->rx_buffersize);
			goto drop;
		}
	}
	if (unlikely(len > 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. */
			sync_descbuffer_for_device(ring, meta->dmaaddr,
						   ring->rx_buffersize);
			*slot = next_slot(ring, *slot);
			cnt++;
			tmp -= ring->rx_buffersize;
			if (tmp <= 0)
				break;
		}
		b43legacyerr(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)) {
		b43legacydbg(ring->dev->wl, "DMA RX: setup_rx_descbuffer()"
			     " failed\n");
		sync_descbuffer_for_device(ring, dmaaddr,
					   ring->rx_buffersize);
		goto drop;
	}

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

	b43legacy_rx(ring->dev, skb, rxhdr);
drop:
	return;
}

void b43legacy_dma_rx(struct b43legacy_dmaring *ring)
{
	const struct b43legacy_dma_ops *ops = ring->ops;
	int slot;
	int current_slot;
	int used_slots = 0;

	B43legacy_WARN_ON(ring->tx);
	current_slot = ops->get_current_rxslot(ring);
	B43legacy_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);
	}
	ops->set_current_rxslot(ring, slot);
	ring->current_slot = slot;
}

static void b43legacy_dma_tx_suspend_ring(struct b43legacy_dmaring *ring)
{
	unsigned long flags;

	spin_lock_irqsave(&ring->lock, flags);
	B43legacy_WARN_ON(!ring->tx);
	ring->ops->tx_suspend(ring);
	spin_unlock_irqrestore(&ring->lock, flags);
}

static void b43legacy_dma_tx_resume_ring(struct b43legacy_dmaring *ring)
{
	unsigned long flags;

	spin_lock_irqsave(&ring->lock, flags);
	B43legacy_WARN_ON(!ring->tx);
	ring->ops->tx_resume(ring);
	spin_unlock_irqrestore(&ring->lock, flags);
}

void b43legacy_dma_tx_suspend(struct b43legacy_wldev *dev)
{
	b43legacy_power_saving_ctl_bits(dev, -1, 1);
	b43legacy_dma_tx_suspend_ring(dev->dma.tx_ring0);
	b43legacy_dma_tx_suspend_ring(dev->dma.tx_ring1);
	b43legacy_dma_tx_suspend_ring(dev->dma.tx_ring2);
	b43legacy_dma_tx_suspend_ring(dev->dma.tx_ring3);
	b43legacy_dma_tx_suspend_ring(dev->dma.tx_ring4);
	b43legacy_dma_tx_suspend_ring(dev->dma.tx_ring5);
}

void b43legacy_dma_tx_resume(struct b43legacy_wldev *dev)
{
	b43legacy_dma_tx_resume_ring(dev->dma.tx_ring5);
	b43legacy_dma_tx_resume_ring(dev->dma.tx_ring4);
	b43legacy_dma_tx_resume_ring(dev->dma.tx_ring3);
	b43legacy_dma_tx_resume_ring(dev->dma.tx_ring2);
	b43legacy_dma_tx_resume_ring(dev->dma.tx_ring1);
	b43legacy_dma_tx_resume_ring(dev->dma.tx_ring0);
	b43legacy_power_saving_ctl_bits(dev, -1, -1);
}