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"

/*
 * TX descriptor ring full threshold
 *
 * The tx_queue descriptor ring fill-level must fall below this value
 * before we restart the netif queue
 */
#define EFX_TXQ_THRESHOLD(_efx) ((_efx)->txq_entries / 2u)

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->unmap_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;
		buffer->unmap_single = false;
	}

	if (buffer->skb) {
		(*pkts_compl)++;
		(*bytes_compl) += buffer->skb->len;
		dev_kfree_skb_any((struct sk_buff *) buffer->skb);
		buffer->skb = NULL;
		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);
	}
}

/**
 * struct efx_tso_header - a DMA mapped buffer for packet headers
 * @next: Linked list of free ones.
 *	The list is protected by the TX queue lock.
 * @dma_unmap_len: Length to unmap for an oversize buffer, or 0.
 * @dma_addr: The DMA address of the header below.
 *
 * This controls the memory used for a TSO header.  Use TSOH_DATA()
 * to find the packet header data.  Use TSOH_SIZE() to calculate the
 * total size required for a given packet header length.  TSO headers
 * in the free list are exactly %TSOH_STD_SIZE bytes in size.
 */
struct efx_tso_header {
	union {
		struct efx_tso_header *next;
		size_t unmap_len;
	};
	dma_addr_t dma_addr;
};

static int efx_enqueue_skb_tso(struct efx_tx_queue *tx_queue,
			       struct sk_buff *skb);
static void efx_fini_tso(struct efx_tx_queue *tx_queue);
static void efx_tsoh_heap_free(struct efx_tx_queue *tx_queue,
			       struct efx_tso_header *tsoh);

static void efx_tsoh_free(struct efx_tx_queue *tx_queue,
			  struct efx_tx_buffer *buffer)
{
	if (buffer->tsoh) {
		if (likely(!buffer->tsoh->unmap_len)) {
			buffer->tsoh->next = tx_queue->tso_headers_free;
			tx_queue->tso_headers_free = buffer->tsoh;
		} else {
			efx_tsoh_heap_free(tx_queue, buffer->tsoh);