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

/****************************************************************************
 * Driver for Solarflare Solarstorm network controllers and boards
 * Copyright 2005-2006 Fen Systems Ltd.
 * Copyright 2005-2008 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/if_ether.h>
#include <linux/highmem.h>
#include "net_driver.h"
#include "tx.h"
#include "efx.h"
#include "falcon.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_NETDEV_TX_THRESHOLD(_tx_queue)	\
	(_tx_queue->efx->type->txd_ring_mask / 2u)

/* We want to be able to nest calls to netif_stop_queue(), since each
 * channel can have an individual stop on the queue.
 */
void efx_stop_queue(struct efx_nic *efx)
{
	spin_lock_bh(&efx->netif_stop_lock);
	EFX_TRACE(efx, "stop TX queue\n");

	atomic_inc(&efx->netif_stop_count);
	netif_stop_queue(efx->net_dev);

	spin_unlock_bh(&efx->netif_stop_lock);
}

/* Wake netif's TX queue
 * We want to be able to nest calls to netif_stop_queue(), since each
 * channel can have an individual stop on the queue.
 */
inline void efx_wake_queue(struct efx_nic *efx)
{
	local_bh_disable();
	if (atomic_dec_and_lock(&efx->netif_stop_count,
				&efx->netif_stop_lock)) {
		EFX_TRACE(efx, "waking TX queue\n");
		netif_wake_queue(efx->net_dev);
		spin_unlock(&efx->netif_stop_lock);
	}
	local_bh_enable();
}

static inline void efx_dequeue_buffer(struct efx_tx_queue *tx_queue,
				      struct efx_tx_buffer *buffer)
{
	if (buffer->unmap_len) {
		struct pci_dev *pci_dev = tx_queue->efx->pci_dev;
		if (buffer->unmap_single)
			pci_unmap_single(pci_dev, buffer->unmap_addr,
					 buffer->unmap_len, PCI_DMA_TODEVICE);
		else
			pci_unmap_page(pci_dev, buffer->unmap_addr,
				       buffer->unmap_len, PCI_DMA_TODEVICE);
		buffer->unmap_len = 0;
		buffer->unmap_single = 0;
	}

	if (buffer->skb) {
		dev_kfree_skb_any((struct sk_buff *) buffer->skb);
		buffer->skb = NULL;
		EFX_TRACE(tx_queue->efx, "TX queue %d transmission id %x "
			  "complete\n", tx_queue->queue, read_ptr);
	}
}

/**
 * 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,
			       const 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 inline 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);
		}
		buffer->tsoh = NULL;
	}
}


/*
 * Add a socket buffer to a TX queue
 *
 * This maps all fragments of a socket buffer for DMA and adds them to
 * the TX queue.  The queue's insert pointer will be incremented by
 * the number of fragments in the socket buffer.
 *
 * If any DMA mapping fails, any mapped fragments will be unmapped,
 * the queue's insert pointer will be restored to its original value.
 *
 * Returns NETDEV_TX_OK or NETDEV_TX_BUSY
 * You must hold netif_tx_lock() to call this function.
 */
static inline int efx_enqueue_skb(struct efx_tx_queue *tx_queue,
				  const struct sk_buff *skb)
{
	struct efx_nic *efx = tx_queue->efx;
	struct pci_dev *