linux/drivers/net/sfc/tx.c

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/****************************************************************************
* 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);
}
}
/*
* 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 *pci_dev = efx->pci_dev;
struct efx_tx_buffer *buffer;
skb_frag_t *fragment;
struct page *page;
int page_offset;
unsigned int len, unmap_len = 0, fill_level, insert_ptr, misalign;
dma_addr_t dma_addr, unmap_addr = 0;
unsigned int dma_len;
unsigned unmap_single;
int q_space, i = 0;
int rc = NETDEV_TX_OK;
EFX_BUG_ON_PARANOID(tx_queue->write_count != tx_queue->insert_count);
/* Get size of the initial fragment */
len = skb_headlen(skb);
fill_level = tx_queue->insert_count - tx_queue->old_read_count;
q_space = efx->type->txd_ring_mask - 1 - fill_level;
/* Map for DMA. Use pci_map_single rather than pci_map_page
* since this is more efficient on machines with sparse
* memory.
*/
unmap_single = 1;
dma_addr = pci_map_single(pci_dev, skb->data, len, PCI_DMA_TODEVICE);
/* Process all fragments */
while (1) {
if (unlikely(pci_dma_mapping_error(dma_addr)))
goto pci_err;
/* Store fields for marking in the per-fragment final
* descriptor */
unmap_len = len;
unmap_addr = dma_addr;
/* Add to TX queue, splitting across DMA boundaries */
do {
if (unlikely(q_space-- <= 0)) {
/* It might be that completions have
* happened since the xmit path last
* checked. Update the xmit path's
* copy of read_count.
*/
++tx_queue->stopped;
/* This memory barrier protects the
* change of stopped from the access
* of read_count. */
smp_mb();
tx_queue->old_read_count =
*(volatile unsigned *)
&tx_queue->read_count;
fill_level = (tx_queue->insert_count
- tx_queue->old_read_count);
q_space = (efx->type->txd_ring_mask - 1 -
fill_level);
if (unlikely(q_space-- <= 0))
goto stop;
smp_mb();
--tx_queue->stopped;
}
insert_ptr = (tx_queue->insert_count &
efx->type->txd_ring_mask);
buffer = &tx_queue->buffer[insert_ptr];
EFX_BUG_ON_PARANOID(buffer->skb);
EFX_BUG_ON_PARANOID(buffer->len);
EFX_BUG_ON_PARANOID(buffer->continuation != 1);
EFX_BUG_ON_PARANOID(buffer->unmap_len);
dma_len = (((~dma_addr) & efx->type->tx_dma_mask) + 1);
if (likely(dma_len > len))
dma_len = len;
misalign = (unsigned)dma_addr & efx->type->bug5391_mask;
if (misalign && dma_len + misalign > 512)
dma_len = 512 - misalign;
/* Fill out per descriptor fields */
buffer->len = dma_len;
buffer->dma_addr = dma_addr;
len -= dma_len;
dma_addr += dma_len;
++tx_queue->insert_count;
} while (len);
/* Transfer ownership of the unmapping to the final buffer */
buffer->unmap_addr = unmap_addr;
buffer->unmap_single = unmap_single;
buffer->unmap_len = unmap_len;
unmap_len = 0;
/* Get address and size of next fragment */
if (i >= skb_shinfo(skb)->nr_frags)
break;
fragment = &skb_shinfo(skb)->frags[i];
len = fragment->size;
page = fragment->page;
page_offset = fragment->page_offset;
i++;
/* Map for DMA */
unmap_single = 0;
dma_addr = pci_map_page(pci_dev, page, page_offset, len,
PCI_DMA_TODEVICE);
}
/* Transfer ownership of the skb to the final buffer */
buffer->skb = skb;
buffer->continuation = 0;
/* Pass off to hardware */
falcon_push_buffers(tx_queue);
return NETDEV_TX_OK;
pci_err:
EFX_ERR_RL(efx, " TX queue %d could not map skb with %d bytes %d "
"fragments for DMA\n", tx_queue->queue, skb->len,
skb_shinfo(skb)->nr_frags + 1);
/* Mark the packet as transmitted, and free the SKB ourselves */
dev_kfree_skb_any((struct sk_buff *)skb);
goto unwind;
stop:
rc = NETDEV_TX_BUSY;
if (tx_queue->stopped == 1)
efx_stop_queue(efx);
unwind:
/* Work backwards until we hit the original insert pointer value */
while (tx_queue->insert_count != tx_queue->write_count) {
--tx_queue->insert_count;
insert_ptr = tx_queue->insert_count & efx->type->txd_ring_mask;
buffer = &tx_queue->buffer[insert_ptr];
efx_dequeue_buffer(tx_queue, buffer);
buffer->len = 0;
}
/* Free the fragment we were mid-way through pushing */
if (unmap_len)
pci_unmap_page(pci_dev, unmap_addr, unmap_len,
PCI_DMA_TODEVICE);
return rc;
}
/* Remove packets from the TX queue
*
* This removes packets from the TX queue, up to and including the
* specified index.
*/
static inline void efx_dequeue_buffers(struct efx_tx_queue *tx_queue,
unsigned int index)
{
struct efx_nic *efx = tx_queue->efx;
unsigned int stop_index, read_ptr;
unsigned int mask = tx_queue->efx->type->txd_ring_mask;
stop_index = (index + 1) & mask;
read_ptr = tx_queue->read_count & mask;
while (read_ptr != stop_index) {
struct efx_tx_buffer *buffer = &tx_queue->buffer[read_ptr];
if (unlikely(buffer->len == 0)) {
EFX_ERR(tx_queue->efx, "TX queue %d spurious TX "
"completion id %x\n", tx_queue->queue,
read_ptr);
efx_schedule_reset(efx, RESET_TYPE_TX_SKIP);
return;
}
efx_dequeue_buffer(tx_queue, buffer);
buffer->continuation = 1;
buffer->len = 0;
++tx_queue->read_count;
read_ptr = tx_queue->read_count & mask;
}
}
/* Initiate a packet transmission on the specified TX queue.
* Note that returning anything other than NETDEV_TX_OK will cause the
* OS to free the skb.
*
* This function is split out from efx_hard_start_xmit to allow the
* loopback test to direct packets via specific TX queues. It is
* therefore a non-static inline, so as not to penalise performance
* for non-loopback transmissions.
*
* Context: netif_tx_lock held
*/
inline int efx_xmit(struct efx_nic *efx,
struct efx_tx_queue *tx_queue, struct sk_buff *skb)
{
int rc;
/* Map fragments for DMA and add to TX queue */
rc = efx_enqueue_skb(tx_queue, skb);
if (unlikely(rc != NETDEV_TX_OK))
goto out;
/* Update last TX timer */
efx->net_dev->trans_start = jiffies;
out:
return rc;
}
/* Initiate a packet transmission. We use one channel per CPU
* (sharing when we have more CPUs than channels). On Falcon, the TX
* completion events will be directed back to the CPU that transmitted
* the packet, which should be cache-efficient.
*
* Context: non-blocking.
* Note that returning anything other than NETDEV_TX_OK will cause the
* OS to free the skb.
*/
int efx_hard_start_xmit(struct sk_buff *skb, struct net_device *net_dev)
{
struct efx_nic *efx = net_dev->priv;
return efx_xmit(efx, &efx->tx_queue[0], skb);
}
void efx_xmit_done(struct efx_tx_queue *tx_queue, unsigned int index)
{
unsigned fill_level;
struct efx_nic *efx = tx_queue->efx;
EFX_BUG_ON_PARANOID(index > efx->type->txd_ring_mask);
efx_dequeue_buffers(tx_queue, index);
/* See if we need to restart the netif queue. This barrier
* separates the update of read_count from the test of
* stopped. */
smp_mb();
if (unlikely(tx_queue->stopped)) {
fill_level = tx_queue->insert_count - tx_queue->read_count;
if (fill_level < EFX_NETDEV_TX_THRESHOLD(tx_queue)) {
EFX_BUG_ON_PARANOID(!NET_DEV_REGISTERED(efx));
/* Do this under netif_tx_lock(), to avoid racing
* with efx_xmit(). */
netif_tx_lock(efx->net_dev);
if (tx_queue->stopped) {
tx_queue->stopped = 0;
efx_wake_queue(efx);
}
netif_tx_unlock(efx->net_dev);
}
}
}
int efx_probe_tx_queue(struct efx_tx_queue *tx_queue)
{
struct efx_nic *efx = tx_queue->efx;
unsigned int txq_size;
int i, rc;
EFX_LOG(efx, "creating TX queue %d\n", tx_queue->queue);
/* Allocate software ring */
txq_size = (efx->type->txd_ring_mask + 1) * sizeof(*tx_queue->buffer);
tx_queue->buffer = kzalloc(txq_size, GFP_KERNEL);
if (!tx_queue->buffer) {
rc = -ENOMEM;
goto fail1;
}
for (i = 0; i <= efx->type->txd_ring_mask; ++i)
tx_queue->buffer[i].continuation = 1;
/* Allocate hardware ring */
rc = falcon_probe_tx(tx_queue);
if (rc)
goto fail2;
return 0;
fail2:
kfree(tx_queue->buffer);
tx_queue->buffer = NULL;
fail1:
tx_queue->used = 0;
return rc;
}
int efx_init_tx_queue(struct efx_tx_queue *tx_queue)
{
EFX_LOG(tx_queue->efx, "initialising TX queue %d\n", tx_queue->queue);
tx_queue->insert_count = 0;
tx_queue->write_count = 0;
tx_queue->read_count = 0;
tx_queue->old_read_count = 0;
BUG_ON(tx_queue->stopped);
/* Set up TX descriptor ring */
return falcon_init_tx(tx_queue);
}
void efx_release_tx_buffers(struct efx_tx_queue *tx_queue)
{
struct efx_tx_buffer *buffer;
if (!tx_queue->buffer)
return;
/* Free any buffers left in the ring */
while (tx_queue->read_count != tx_queue->write_count) {
buffer = &tx_queue->buffer[tx_queue->read_count &
tx_queue->efx->type->txd_ring_mask];
efx_dequeue_buffer(tx_queue, buffer);
buffer->continuation = 1;
buffer->len = 0;
++tx_queue->read_count;
}
}
void efx_fini_tx_queue(struct efx_tx_queue *tx_queue)
{
EFX_LOG(tx_queue->efx, "shutting down TX queue %d\n", tx_queue->queue);
/* Flush TX queue, remove descriptor ring */
falcon_fini_tx(tx_queue);
efx_release_tx_buffers(tx_queue);
/* Release queue's stop on port, if any */
if (tx_queue->stopped) {
tx_queue->stopped = 0;
efx_wake_queue(tx_queue->efx);
}
}
void efx_remove_tx_queue(struct efx_tx_queue *tx_queue)
{
EFX_LOG(tx_queue->efx, "destroying TX queue %d\n", tx_queue->queue);
falcon_remove_tx(tx_queue);
kfree(tx_queue->buffer);
tx_queue->buffer = NULL;
tx_queue->used = 0;
}