summaryrefslogtreecommitdiffstats
path: root/drivers/net/sfc/tx.c
blob: fbb866b2185ebdd5e37317f9f18341e23ed684e6 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
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;
}