1 files changed, 452 insertions, 0 deletions

diff --git a/drivers/net/sfc/tx.c b/drivers/net/sfc/tx.c
new file mode 100644
index 00000000000..fbb866b2185
--- /dev/null
+++ b/drivers/net/sfc/tx.c
@@ -0,0 +1,452 @@
+/****************************************************************************
+ * 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;
+}
+
+