path: root/drivers/net/ethernet/sfc/tx.c

/****************************************************************************
 * Driver for Solarflare Solarstorm network controllers and boards
 * Copyright 2005-2006 Fen Systems Ltd.
 * Copyright 2005-2010 Solarflare Communications Inc.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation, incorporated herein by reference.
 */

#include <linux/pci.h>
#include <linux/tcp.h>
#include <linux/ip.h>
#include <linux/in.h>
#include <linux/ipv6.h>
#include <linux/slab.h>
#include <net/ipv6.h>
#include <linux/if_ether.h>
#include <linux/highmem.h>
#include "net_driver.h"
#include "efx.h"
#include "nic.h"
#include "workarounds.h"

static void efx_dequeue_buffer(struct efx_tx_queue *tx_queue,
			       struct efx_tx_buffer *buffer,
			       unsigned int *pkts_compl,
			       unsigned int *bytes_compl)
{
	if (buffer->unmap_len) {
		struct device *dma_dev = &tx_queue->efx->pci_dev->dev;
		dma_addr_t unmap_addr = (buffer->dma_addr + buffer->len -
					 buffer->unmap_len);
		if (buffer->flags & EFX_TX_BUF_MAP_SINGLE)
			dma_unmap_single(dma_dev, unmap_addr, buffer->unmap_len,
					 DMA_TO_DEVICE);
		else
			dma_unmap_page(dma_dev, unmap_addr, buffer->unmap_len,
				       DMA_TO_DEVICE);
		buffer->unmap_len = 0;
	}

	if (buffer->flags & EFX_TX_BUF_SKB) {
		(*pkts_compl)++;
		(*bytes_compl) += buffer->skb->len;
		dev_kfree_skb_any((struct sk_buff *) buffer->skb);
		netif_vdbg(tx_queue->efx, tx_done, tx_queue->efx->net_dev,
			   "TX queue %d transmission id %x complete\n",
			   tx_queue->queue, tx_queue->read_count);
	} else if (buffer->flags & EFX_TX_BUF_HEAP) {
		kfree(buffer->heap_buf);
	}

	buffer->len = 0;
	buffer->flags = 0;
}

static int efx_enqueue_skb_tso(struct efx_tx_queue *tx_queue,
			       struct sk_buff *skb);

static inline unsigned
efx_max_tx_len(struct efx_nic *efx, dma_addr_t dma_addr)
{
	/* Depending on the NIC revision, we can use descriptor
	 * lengths up to 8K or 8K-1.  However, since PCI Express
	 * devices must split read requests at 4K boundaries, there is
	 * little benefit from using descriptors that cross those
	 * boundaries and we keep things simple by not doing so.
	 */
	unsigned len = (~dma_addr & (EFX_PAGE_SIZE - 1)) + 1;

	/* Work around hardware bug for unaligned buffers. */
	if (EFX_WORKAROUND_5391(efx) && (dma_addr & 0xf))
		len = min_t(unsigned, len, 512 - (dma_addr & 0xf));

	return len;
}

unsigned int efx_tx_max_skb_descs(struct efx_nic *efx)
{
	/* Header and payload descriptor for each output segment, plus
	 * one for every input fragment boundary within a segment
	 */
	unsigned int max_descs = EFX_TSO_MAX_SEGS * 2 + MAX_SKB_FRAGS;

	/* Possibly one more per segment for the alignment workaround */
	if (EFX_WORKAROUND_5391(efx))
		max_descs += EFX_TSO_MAX_SEGS;

	/* Possibly more for PCIe page boundaries within input fragments */
	if (PAGE_SIZE > EFX_PAGE_SIZE)
		max_descs += max_t(unsigned int, MAX_SKB_FRAGS,
				   DIV_ROUND_UP(GSO_MAX_SIZE, EFX_PAGE_SIZE));

	return max_descs;
}

/* Get partner of a TX queue, seen as part of the same net core queue */
static struct efx_tx_queue *efx_tx_queue_partner(struct efx_tx_queue *tx_queue)
{
	if (tx_queue->queue & EFX_TXQ_TYPE_OFFLOAD)
		return tx_queue - EFX_TXQ_TYPE_OFFLOAD;
	else
		return tx_queue + EFX_TXQ_TYPE_OFFLOAD;
}

static void efx_tx_maybe_stop_queue(struct efx_tx_queue *txq1)
{
	/* We need to consider both queues that the net core sees as one */
	struct efx_tx_queue *txq2 = efx_tx_queue_partner(txq1);
	struct efx_nic *efx = txq1->efx;
	unsigned int fill_level;

	fill_level = max(txq1->insert_count - txq1->old_read_count,
			 txq2->insert_count - txq2->old_read_count);
	if (likely(fill_level < efx->txq_stop_thresh))