Merge branches 'x86/paravirt', 'x86/pat', 'x86/setup-v2', 'x86/subarch', 'x86/uaccess...
[linux-2.6] / drivers / net / sfc / tx.c
1 /****************************************************************************
2  * Driver for Solarflare Solarstorm network controllers and boards
3  * Copyright 2005-2006 Fen Systems Ltd.
4  * Copyright 2005-2008 Solarflare Communications Inc.
5  *
6  * This program is free software; you can redistribute it and/or modify it
7  * under the terms of the GNU General Public License version 2 as published
8  * by the Free Software Foundation, incorporated herein by reference.
9  */
10
11 #include <linux/pci.h>
12 #include <linux/tcp.h>
13 #include <linux/ip.h>
14 #include <linux/in.h>
15 #include <linux/if_ether.h>
16 #include <linux/highmem.h>
17 #include "net_driver.h"
18 #include "tx.h"
19 #include "efx.h"
20 #include "falcon.h"
21 #include "workarounds.h"
22
23 /*
24  * TX descriptor ring full threshold
25  *
26  * The tx_queue descriptor ring fill-level must fall below this value
27  * before we restart the netif queue
28  */
29 #define EFX_NETDEV_TX_THRESHOLD(_tx_queue)      \
30         (_tx_queue->efx->type->txd_ring_mask / 2u)
31
32 /* We want to be able to nest calls to netif_stop_queue(), since each
33  * channel can have an individual stop on the queue.
34  */
35 void efx_stop_queue(struct efx_nic *efx)
36 {
37         spin_lock_bh(&efx->netif_stop_lock);
38         EFX_TRACE(efx, "stop TX queue\n");
39
40         atomic_inc(&efx->netif_stop_count);
41         netif_stop_queue(efx->net_dev);
42
43         spin_unlock_bh(&efx->netif_stop_lock);
44 }
45
46 /* Wake netif's TX queue
47  * We want to be able to nest calls to netif_stop_queue(), since each
48  * channel can have an individual stop on the queue.
49  */
50 void efx_wake_queue(struct efx_nic *efx)
51 {
52         local_bh_disable();
53         if (atomic_dec_and_lock(&efx->netif_stop_count,
54                                 &efx->netif_stop_lock)) {
55                 EFX_TRACE(efx, "waking TX queue\n");
56                 netif_wake_queue(efx->net_dev);
57                 spin_unlock(&efx->netif_stop_lock);
58         }
59         local_bh_enable();
60 }
61
62 static void efx_dequeue_buffer(struct efx_tx_queue *tx_queue,
63                                struct efx_tx_buffer *buffer)
64 {
65         if (buffer->unmap_len) {
66                 struct pci_dev *pci_dev = tx_queue->efx->pci_dev;
67                 dma_addr_t unmap_addr = (buffer->dma_addr + buffer->len -
68                                          buffer->unmap_len);
69                 if (buffer->unmap_single)
70                         pci_unmap_single(pci_dev, unmap_addr, buffer->unmap_len,
71                                          PCI_DMA_TODEVICE);
72                 else
73                         pci_unmap_page(pci_dev, unmap_addr, buffer->unmap_len,
74                                        PCI_DMA_TODEVICE);
75                 buffer->unmap_len = 0;
76                 buffer->unmap_single = false;
77         }
78
79         if (buffer->skb) {
80                 dev_kfree_skb_any((struct sk_buff *) buffer->skb);
81                 buffer->skb = NULL;
82                 EFX_TRACE(tx_queue->efx, "TX queue %d transmission id %x "
83                           "complete\n", tx_queue->queue, read_ptr);
84         }
85 }
86
87 /**
88  * struct efx_tso_header - a DMA mapped buffer for packet headers
89  * @next: Linked list of free ones.
90  *      The list is protected by the TX queue lock.
91  * @dma_unmap_len: Length to unmap for an oversize buffer, or 0.
92  * @dma_addr: The DMA address of the header below.
93  *
94  * This controls the memory used for a TSO header.  Use TSOH_DATA()
95  * to find the packet header data.  Use TSOH_SIZE() to calculate the
96  * total size required for a given packet header length.  TSO headers
97  * in the free list are exactly %TSOH_STD_SIZE bytes in size.
98  */
99 struct efx_tso_header {
100         union {
101                 struct efx_tso_header *next;
102                 size_t unmap_len;
103         };
104         dma_addr_t dma_addr;
105 };
106
107 static int efx_enqueue_skb_tso(struct efx_tx_queue *tx_queue,
108                                struct sk_buff *skb);
109 static void efx_fini_tso(struct efx_tx_queue *tx_queue);
110 static void efx_tsoh_heap_free(struct efx_tx_queue *tx_queue,
111                                struct efx_tso_header *tsoh);
112
113 static void efx_tsoh_free(struct efx_tx_queue *tx_queue,
114                           struct efx_tx_buffer *buffer)
115 {
116         if (buffer->tsoh) {
117                 if (likely(!buffer->tsoh->unmap_len)) {
118                         buffer->tsoh->next = tx_queue->tso_headers_free;
119                         tx_queue->tso_headers_free = buffer->tsoh;
120                 } else {
121                         efx_tsoh_heap_free(tx_queue, buffer->tsoh);
122                 }
123                 buffer->tsoh = NULL;
124         }
125 }
126
127
128 /*
129  * Add a socket buffer to a TX queue
130  *
131  * This maps all fragments of a socket buffer for DMA and adds them to
132  * the TX queue.  The queue's insert pointer will be incremented by
133  * the number of fragments in the socket buffer.
134  *
135  * If any DMA mapping fails, any mapped fragments will be unmapped,
136  * the queue's insert pointer will be restored to its original value.
137  *
138  * Returns NETDEV_TX_OK or NETDEV_TX_BUSY
139  * You must hold netif_tx_lock() to call this function.
140  */
141 static int efx_enqueue_skb(struct efx_tx_queue *tx_queue,
142                            struct sk_buff *skb)
143 {
144         struct efx_nic *efx = tx_queue->efx;
145         struct pci_dev *pci_dev = efx->pci_dev;
146         struct efx_tx_buffer *buffer;
147         skb_frag_t *fragment;
148         struct page *page;
149         int page_offset;
150         unsigned int len, unmap_len = 0, fill_level, insert_ptr, misalign;
151         dma_addr_t dma_addr, unmap_addr = 0;
152         unsigned int dma_len;
153         bool unmap_single;
154         int q_space, i = 0;
155         int rc = NETDEV_TX_OK;
156
157         EFX_BUG_ON_PARANOID(tx_queue->write_count != tx_queue->insert_count);
158
159         if (skb_shinfo((struct sk_buff *)skb)->gso_size)
160                 return efx_enqueue_skb_tso(tx_queue, skb);
161
162         /* Get size of the initial fragment */
163         len = skb_headlen(skb);
164
165         fill_level = tx_queue->insert_count - tx_queue->old_read_count;
166         q_space = efx->type->txd_ring_mask - 1 - fill_level;
167
168         /* Map for DMA.  Use pci_map_single rather than pci_map_page
169          * since this is more efficient on machines with sparse
170          * memory.
171          */
172         unmap_single = true;
173         dma_addr = pci_map_single(pci_dev, skb->data, len, PCI_DMA_TODEVICE);
174
175         /* Process all fragments */
176         while (1) {
177                 if (unlikely(pci_dma_mapping_error(pci_dev, dma_addr)))
178                         goto pci_err;
179
180                 /* Store fields for marking in the per-fragment final
181                  * descriptor */
182                 unmap_len = len;
183                 unmap_addr = dma_addr;
184
185                 /* Add to TX queue, splitting across DMA boundaries */
186                 do {
187                         if (unlikely(q_space-- <= 0)) {
188                                 /* It might be that completions have
189                                  * happened since the xmit path last
190                                  * checked.  Update the xmit path's
191                                  * copy of read_count.
192                                  */
193                                 ++tx_queue->stopped;
194                                 /* This memory barrier protects the
195                                  * change of stopped from the access
196                                  * of read_count. */
197                                 smp_mb();
198                                 tx_queue->old_read_count =
199                                         *(volatile unsigned *)
200                                         &tx_queue->read_count;
201                                 fill_level = (tx_queue->insert_count
202                                               - tx_queue->old_read_count);
203                                 q_space = (efx->type->txd_ring_mask - 1 -
204                                            fill_level);
205                                 if (unlikely(q_space-- <= 0))
206                                         goto stop;
207                                 smp_mb();
208                                 --tx_queue->stopped;
209                         }
210
211                         insert_ptr = (tx_queue->insert_count &
212                                       efx->type->txd_ring_mask);
213                         buffer = &tx_queue->buffer[insert_ptr];
214                         efx_tsoh_free(tx_queue, buffer);
215                         EFX_BUG_ON_PARANOID(buffer->tsoh);
216                         EFX_BUG_ON_PARANOID(buffer->skb);
217                         EFX_BUG_ON_PARANOID(buffer->len);
218                         EFX_BUG_ON_PARANOID(!buffer->continuation);
219                         EFX_BUG_ON_PARANOID(buffer->unmap_len);
220
221                         dma_len = (((~dma_addr) & efx->type->tx_dma_mask) + 1);
222                         if (likely(dma_len > len))
223                                 dma_len = len;
224
225                         misalign = (unsigned)dma_addr & efx->type->bug5391_mask;
226                         if (misalign && dma_len + misalign > 512)
227                                 dma_len = 512 - misalign;
228
229                         /* Fill out per descriptor fields */
230                         buffer->len = dma_len;
231                         buffer->dma_addr = dma_addr;
232                         len -= dma_len;
233                         dma_addr += dma_len;
234                         ++tx_queue->insert_count;
235                 } while (len);
236
237                 /* Transfer ownership of the unmapping to the final buffer */
238                 buffer->unmap_single = unmap_single;
239                 buffer->unmap_len = unmap_len;
240                 unmap_len = 0;
241
242                 /* Get address and size of next fragment */
243                 if (i >= skb_shinfo(skb)->nr_frags)
244                         break;
245                 fragment = &skb_shinfo(skb)->frags[i];
246                 len = fragment->size;
247                 page = fragment->page;
248                 page_offset = fragment->page_offset;
249                 i++;
250                 /* Map for DMA */
251                 unmap_single = false;
252                 dma_addr = pci_map_page(pci_dev, page, page_offset, len,
253                                         PCI_DMA_TODEVICE);
254         }
255
256         /* Transfer ownership of the skb to the final buffer */
257         buffer->skb = skb;
258         buffer->continuation = false;
259
260         /* Pass off to hardware */
261         falcon_push_buffers(tx_queue);
262
263         return NETDEV_TX_OK;
264
265  pci_err:
266         EFX_ERR_RL(efx, " TX queue %d could not map skb with %d bytes %d "
267                    "fragments for DMA\n", tx_queue->queue, skb->len,
268                    skb_shinfo(skb)->nr_frags + 1);
269
270         /* Mark the packet as transmitted, and free the SKB ourselves */
271         dev_kfree_skb_any((struct sk_buff *)skb);
272         goto unwind;
273
274  stop:
275         rc = NETDEV_TX_BUSY;
276
277         if (tx_queue->stopped == 1)
278                 efx_stop_queue(efx);
279
280  unwind:
281         /* Work backwards until we hit the original insert pointer value */
282         while (tx_queue->insert_count != tx_queue->write_count) {
283                 --tx_queue->insert_count;
284                 insert_ptr = tx_queue->insert_count & efx->type->txd_ring_mask;
285                 buffer = &tx_queue->buffer[insert_ptr];
286                 efx_dequeue_buffer(tx_queue, buffer);
287                 buffer->len = 0;
288         }
289
290         /* Free the fragment we were mid-way through pushing */
291         if (unmap_len) {
292                 if (unmap_single)
293                         pci_unmap_single(pci_dev, unmap_addr, unmap_len,
294                                          PCI_DMA_TODEVICE);
295                 else
296                         pci_unmap_page(pci_dev, unmap_addr, unmap_len,
297                                        PCI_DMA_TODEVICE);
298         }
299
300         return rc;
301 }
302
303 /* Remove packets from the TX queue
304  *
305  * This removes packets from the TX queue, up to and including the
306  * specified index.
307  */
308 static void efx_dequeue_buffers(struct efx_tx_queue *tx_queue,
309                                 unsigned int index)
310 {
311         struct efx_nic *efx = tx_queue->efx;
312         unsigned int stop_index, read_ptr;
313         unsigned int mask = tx_queue->efx->type->txd_ring_mask;
314
315         stop_index = (index + 1) & mask;
316         read_ptr = tx_queue->read_count & mask;
317
318         while (read_ptr != stop_index) {
319                 struct efx_tx_buffer *buffer = &tx_queue->buffer[read_ptr];
320                 if (unlikely(buffer->len == 0)) {
321                         EFX_ERR(tx_queue->efx, "TX queue %d spurious TX "
322                                 "completion id %x\n", tx_queue->queue,
323                                 read_ptr);
324                         efx_schedule_reset(efx, RESET_TYPE_TX_SKIP);
325                         return;
326                 }
327
328                 efx_dequeue_buffer(tx_queue, buffer);
329                 buffer->continuation = true;
330                 buffer->len = 0;
331
332                 ++tx_queue->read_count;
333                 read_ptr = tx_queue->read_count & mask;
334         }
335 }
336
337 /* Initiate a packet transmission on the specified TX queue.
338  * Note that returning anything other than NETDEV_TX_OK will cause the
339  * OS to free the skb.
340  *
341  * This function is split out from efx_hard_start_xmit to allow the
342  * loopback test to direct packets via specific TX queues.  It is
343  * therefore a non-static inline, so as not to penalise performance
344  * for non-loopback transmissions.
345  *
346  * Context: netif_tx_lock held
347  */
348 inline int efx_xmit(struct efx_nic *efx,
349                     struct efx_tx_queue *tx_queue, struct sk_buff *skb)
350 {
351         int rc;
352
353         /* Map fragments for DMA and add to TX queue */
354         rc = efx_enqueue_skb(tx_queue, skb);
355         if (unlikely(rc != NETDEV_TX_OK))
356                 goto out;
357
358         /* Update last TX timer */
359         efx->net_dev->trans_start = jiffies;
360
361  out:
362         return rc;
363 }
364
365 /* Initiate a packet transmission.  We use one channel per CPU
366  * (sharing when we have more CPUs than channels).  On Falcon, the TX
367  * completion events will be directed back to the CPU that transmitted
368  * the packet, which should be cache-efficient.
369  *
370  * Context: non-blocking.
371  * Note that returning anything other than NETDEV_TX_OK will cause the
372  * OS to free the skb.
373  */
374 int efx_hard_start_xmit(struct sk_buff *skb, struct net_device *net_dev)
375 {
376         struct efx_nic *efx = netdev_priv(net_dev);
377         struct efx_tx_queue *tx_queue;
378
379         if (likely(skb->ip_summed == CHECKSUM_PARTIAL))
380                 tx_queue = &efx->tx_queue[EFX_TX_QUEUE_OFFLOAD_CSUM];
381         else
382                 tx_queue = &efx->tx_queue[EFX_TX_QUEUE_NO_CSUM];
383
384         return efx_xmit(efx, tx_queue, skb);
385 }
386
387 void efx_xmit_done(struct efx_tx_queue *tx_queue, unsigned int index)
388 {
389         unsigned fill_level;
390         struct efx_nic *efx = tx_queue->efx;
391
392         EFX_BUG_ON_PARANOID(index > efx->type->txd_ring_mask);
393
394         efx_dequeue_buffers(tx_queue, index);
395
396         /* See if we need to restart the netif queue.  This barrier
397          * separates the update of read_count from the test of
398          * stopped. */
399         smp_mb();
400         if (unlikely(tx_queue->stopped)) {
401                 fill_level = tx_queue->insert_count - tx_queue->read_count;
402                 if (fill_level < EFX_NETDEV_TX_THRESHOLD(tx_queue)) {
403                         EFX_BUG_ON_PARANOID(!efx_dev_registered(efx));
404
405                         /* Do this under netif_tx_lock(), to avoid racing
406                          * with efx_xmit(). */
407                         netif_tx_lock(efx->net_dev);
408                         if (tx_queue->stopped) {
409                                 tx_queue->stopped = 0;
410                                 efx_wake_queue(efx);
411                         }
412                         netif_tx_unlock(efx->net_dev);
413                 }
414         }
415 }
416
417 int efx_probe_tx_queue(struct efx_tx_queue *tx_queue)
418 {
419         struct efx_nic *efx = tx_queue->efx;
420         unsigned int txq_size;
421         int i, rc;
422
423         EFX_LOG(efx, "creating TX queue %d\n", tx_queue->queue);
424
425         /* Allocate software ring */
426         txq_size = (efx->type->txd_ring_mask + 1) * sizeof(*tx_queue->buffer);
427         tx_queue->buffer = kzalloc(txq_size, GFP_KERNEL);
428         if (!tx_queue->buffer)
429                 return -ENOMEM;
430         for (i = 0; i <= efx->type->txd_ring_mask; ++i)
431                 tx_queue->buffer[i].continuation = true;
432
433         /* Allocate hardware ring */
434         rc = falcon_probe_tx(tx_queue);
435         if (rc)
436                 goto fail;
437
438         return 0;
439
440  fail:
441         kfree(tx_queue->buffer);
442         tx_queue->buffer = NULL;
443         return rc;
444 }
445
446 void efx_init_tx_queue(struct efx_tx_queue *tx_queue)
447 {
448         EFX_LOG(tx_queue->efx, "initialising TX queue %d\n", tx_queue->queue);
449
450         tx_queue->insert_count = 0;
451         tx_queue->write_count = 0;
452         tx_queue->read_count = 0;
453         tx_queue->old_read_count = 0;
454         BUG_ON(tx_queue->stopped);
455
456         /* Set up TX descriptor ring */
457         falcon_init_tx(tx_queue);
458 }
459
460 void efx_release_tx_buffers(struct efx_tx_queue *tx_queue)
461 {
462         struct efx_tx_buffer *buffer;
463
464         if (!tx_queue->buffer)
465                 return;
466
467         /* Free any buffers left in the ring */
468         while (tx_queue->read_count != tx_queue->write_count) {
469                 buffer = &tx_queue->buffer[tx_queue->read_count &
470                                            tx_queue->efx->type->txd_ring_mask];
471                 efx_dequeue_buffer(tx_queue, buffer);
472                 buffer->continuation = true;
473                 buffer->len = 0;
474
475                 ++tx_queue->read_count;
476         }
477 }
478
479 void efx_fini_tx_queue(struct efx_tx_queue *tx_queue)
480 {
481         EFX_LOG(tx_queue->efx, "shutting down TX queue %d\n", tx_queue->queue);
482
483         /* Flush TX queue, remove descriptor ring */
484         falcon_fini_tx(tx_queue);
485
486         efx_release_tx_buffers(tx_queue);
487
488         /* Free up TSO header cache */
489         efx_fini_tso(tx_queue);
490
491         /* Release queue's stop on port, if any */
492         if (tx_queue->stopped) {
493                 tx_queue->stopped = 0;
494                 efx_wake_queue(tx_queue->efx);
495         }
496 }
497
498 void efx_remove_tx_queue(struct efx_tx_queue *tx_queue)
499 {
500         EFX_LOG(tx_queue->efx, "destroying TX queue %d\n", tx_queue->queue);
501         falcon_remove_tx(tx_queue);
502
503         kfree(tx_queue->buffer);
504         tx_queue->buffer = NULL;
505 }
506
507
508 /* Efx TCP segmentation acceleration.
509  *
510  * Why?  Because by doing it here in the driver we can go significantly
511  * faster than the GSO.
512  *
513  * Requires TX checksum offload support.
514  */
515
516 /* Number of bytes inserted at the start of a TSO header buffer,
517  * similar to NET_IP_ALIGN.
518  */
519 #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
520 #define TSOH_OFFSET     0
521 #else
522 #define TSOH_OFFSET     NET_IP_ALIGN
523 #endif
524
525 #define TSOH_BUFFER(tsoh)       ((u8 *)(tsoh + 1) + TSOH_OFFSET)
526
527 /* Total size of struct efx_tso_header, buffer and padding */
528 #define TSOH_SIZE(hdr_len)                                      \
529         (sizeof(struct efx_tso_header) + TSOH_OFFSET + hdr_len)
530
531 /* Size of blocks on free list.  Larger blocks must be allocated from
532  * the heap.
533  */
534 #define TSOH_STD_SIZE           128
535
536 #define PTR_DIFF(p1, p2)  ((u8 *)(p1) - (u8 *)(p2))
537 #define ETH_HDR_LEN(skb)  (skb_network_header(skb) - (skb)->data)
538 #define SKB_TCP_OFF(skb)  PTR_DIFF(tcp_hdr(skb), (skb)->data)
539 #define SKB_IPV4_OFF(skb) PTR_DIFF(ip_hdr(skb), (skb)->data)
540
541 /**
542  * struct tso_state - TSO state for an SKB
543  * @out_len: Remaining length in current segment
544  * @seqnum: Current sequence number
545  * @ipv4_id: Current IPv4 ID, host endian
546  * @packet_space: Remaining space in current packet
547  * @dma_addr: DMA address of current position
548  * @in_len: Remaining length in current SKB fragment
549  * @unmap_len: Length of SKB fragment
550  * @unmap_addr: DMA address of SKB fragment
551  * @unmap_single: DMA single vs page mapping flag
552  * @header_len: Number of bytes of header
553  * @full_packet_size: Number of bytes to put in each outgoing segment
554  *
555  * The state used during segmentation.  It is put into this data structure
556  * just to make it easy to pass into inline functions.
557  */
558 struct tso_state {
559         /* Output position */
560         unsigned out_len;
561         unsigned seqnum;
562         unsigned ipv4_id;
563         unsigned packet_space;
564
565         /* Input position */
566         dma_addr_t dma_addr;
567         unsigned in_len;
568         unsigned unmap_len;
569         dma_addr_t unmap_addr;
570         bool unmap_single;
571
572         unsigned header_len;
573         int full_packet_size;
574 };
575
576
577 /*
578  * Verify that our various assumptions about sk_buffs and the conditions
579  * under which TSO will be attempted hold true.
580  */
581 static void efx_tso_check_safe(struct sk_buff *skb)
582 {
583         __be16 protocol = skb->protocol;
584
585         EFX_BUG_ON_PARANOID(((struct ethhdr *)skb->data)->h_proto !=
586                             protocol);
587         if (protocol == htons(ETH_P_8021Q)) {
588                 /* Find the encapsulated protocol; reset network header
589                  * and transport header based on that. */
590                 struct vlan_ethhdr *veh = (struct vlan_ethhdr *)skb->data;
591                 protocol = veh->h_vlan_encapsulated_proto;
592                 skb_set_network_header(skb, sizeof(*veh));
593                 if (protocol == htons(ETH_P_IP))
594                         skb_set_transport_header(skb, sizeof(*veh) +
595                                                  4 * ip_hdr(skb)->ihl);
596         }
597
598         EFX_BUG_ON_PARANOID(protocol != htons(ETH_P_IP));
599         EFX_BUG_ON_PARANOID(ip_hdr(skb)->protocol != IPPROTO_TCP);
600         EFX_BUG_ON_PARANOID((PTR_DIFF(tcp_hdr(skb), skb->data)
601                              + (tcp_hdr(skb)->doff << 2u)) >
602                             skb_headlen(skb));
603 }
604
605
606 /*
607  * Allocate a page worth of efx_tso_header structures, and string them
608  * into the tx_queue->tso_headers_free linked list. Return 0 or -ENOMEM.
609  */
610 static int efx_tsoh_block_alloc(struct efx_tx_queue *tx_queue)
611 {
612
613         struct pci_dev *pci_dev = tx_queue->efx->pci_dev;
614         struct efx_tso_header *tsoh;
615         dma_addr_t dma_addr;
616         u8 *base_kva, *kva;
617
618         base_kva = pci_alloc_consistent(pci_dev, PAGE_SIZE, &dma_addr);
619         if (base_kva == NULL) {
620                 EFX_ERR(tx_queue->efx, "Unable to allocate page for TSO"
621                         " headers\n");
622                 return -ENOMEM;
623         }
624
625         /* pci_alloc_consistent() allocates pages. */
626         EFX_BUG_ON_PARANOID(dma_addr & (PAGE_SIZE - 1u));
627
628         for (kva = base_kva; kva < base_kva + PAGE_SIZE; kva += TSOH_STD_SIZE) {
629                 tsoh = (struct efx_tso_header *)kva;
630                 tsoh->dma_addr = dma_addr + (TSOH_BUFFER(tsoh) - base_kva);
631                 tsoh->next = tx_queue->tso_headers_free;
632                 tx_queue->tso_headers_free = tsoh;
633         }
634
635         return 0;
636 }
637
638
639 /* Free up a TSO header, and all others in the same page. */
640 static void efx_tsoh_block_free(struct efx_tx_queue *tx_queue,
641                                 struct efx_tso_header *tsoh,
642                                 struct pci_dev *pci_dev)
643 {
644         struct efx_tso_header **p;
645         unsigned long base_kva;
646         dma_addr_t base_dma;
647
648         base_kva = (unsigned long)tsoh & PAGE_MASK;
649         base_dma = tsoh->dma_addr & PAGE_MASK;
650
651         p = &tx_queue->tso_headers_free;
652         while (*p != NULL) {
653                 if (((unsigned long)*p & PAGE_MASK) == base_kva)
654                         *p = (*p)->next;
655                 else
656                         p = &(*p)->next;
657         }
658
659         pci_free_consistent(pci_dev, PAGE_SIZE, (void *)base_kva, base_dma);
660 }
661
662 static struct efx_tso_header *
663 efx_tsoh_heap_alloc(struct efx_tx_queue *tx_queue, size_t header_len)
664 {
665         struct efx_tso_header *tsoh;
666
667         tsoh = kmalloc(TSOH_SIZE(header_len), GFP_ATOMIC | GFP_DMA);
668         if (unlikely(!tsoh))
669                 return NULL;
670
671         tsoh->dma_addr = pci_map_single(tx_queue->efx->pci_dev,
672                                         TSOH_BUFFER(tsoh), header_len,
673                                         PCI_DMA_TODEVICE);
674         if (unlikely(pci_dma_mapping_error(tx_queue->efx->pci_dev,
675                                            tsoh->dma_addr))) {
676                 kfree(tsoh);
677                 return NULL;
678         }
679
680         tsoh->unmap_len = header_len;
681         return tsoh;
682 }
683
684 static void
685 efx_tsoh_heap_free(struct efx_tx_queue *tx_queue, struct efx_tso_header *tsoh)
686 {
687         pci_unmap_single(tx_queue->efx->pci_dev,
688                          tsoh->dma_addr, tsoh->unmap_len,
689                          PCI_DMA_TODEVICE);
690         kfree(tsoh);
691 }
692
693 /**
694  * efx_tx_queue_insert - push descriptors onto the TX queue
695  * @tx_queue:           Efx TX queue
696  * @dma_addr:           DMA address of fragment
697  * @len:                Length of fragment
698  * @final_buffer:       The final buffer inserted into the queue
699  *
700  * Push descriptors onto the TX queue.  Return 0 on success or 1 if
701  * @tx_queue full.
702  */
703 static int efx_tx_queue_insert(struct efx_tx_queue *tx_queue,
704                                dma_addr_t dma_addr, unsigned len,
705                                struct efx_tx_buffer **final_buffer)
706 {
707         struct efx_tx_buffer *buffer;
708         struct efx_nic *efx = tx_queue->efx;
709         unsigned dma_len, fill_level, insert_ptr, misalign;
710         int q_space;
711
712         EFX_BUG_ON_PARANOID(len <= 0);
713
714         fill_level = tx_queue->insert_count - tx_queue->old_read_count;
715         /* -1 as there is no way to represent all descriptors used */
716         q_space = efx->type->txd_ring_mask - 1 - fill_level;
717
718         while (1) {
719                 if (unlikely(q_space-- <= 0)) {
720                         /* It might be that completions have happened
721                          * since the xmit path last checked.  Update
722                          * the xmit path's copy of read_count.
723                          */
724                         ++tx_queue->stopped;
725                         /* This memory barrier protects the change of
726                          * stopped from the access of read_count. */
727                         smp_mb();
728                         tx_queue->old_read_count =
729                                 *(volatile unsigned *)&tx_queue->read_count;
730                         fill_level = (tx_queue->insert_count
731                                       - tx_queue->old_read_count);
732                         q_space = efx->type->txd_ring_mask - 1 - fill_level;
733                         if (unlikely(q_space-- <= 0)) {
734                                 *final_buffer = NULL;
735                                 return 1;
736                         }
737                         smp_mb();
738                         --tx_queue->stopped;
739                 }
740
741                 insert_ptr = tx_queue->insert_count & efx->type->txd_ring_mask;
742                 buffer = &tx_queue->buffer[insert_ptr];
743                 ++tx_queue->insert_count;
744
745                 EFX_BUG_ON_PARANOID(tx_queue->insert_count -
746                                     tx_queue->read_count >
747                                     efx->type->txd_ring_mask);
748
749                 efx_tsoh_free(tx_queue, buffer);
750                 EFX_BUG_ON_PARANOID(buffer->len);
751                 EFX_BUG_ON_PARANOID(buffer->unmap_len);
752                 EFX_BUG_ON_PARANOID(buffer->skb);
753                 EFX_BUG_ON_PARANOID(!buffer->continuation);
754                 EFX_BUG_ON_PARANOID(buffer->tsoh);
755
756                 buffer->dma_addr = dma_addr;
757
758                 /* Ensure we do not cross a boundary unsupported by H/W */
759                 dma_len = (~dma_addr & efx->type->tx_dma_mask) + 1;
760
761                 misalign = (unsigned)dma_addr & efx->type->bug5391_mask;
762                 if (misalign && dma_len + misalign > 512)
763                         dma_len = 512 - misalign;
764
765                 /* If there is enough space to send then do so */
766                 if (dma_len >= len)
767                         break;
768
769                 buffer->len = dma_len; /* Don't set the other members */
770                 dma_addr += dma_len;
771                 len -= dma_len;
772         }
773
774         EFX_BUG_ON_PARANOID(!len);
775         buffer->len = len;
776         *final_buffer = buffer;
777         return 0;
778 }
779
780
781 /*
782  * Put a TSO header into the TX queue.
783  *
784  * This is special-cased because we know that it is small enough to fit in
785  * a single fragment, and we know it doesn't cross a page boundary.  It
786  * also allows us to not worry about end-of-packet etc.
787  */
788 static void efx_tso_put_header(struct efx_tx_queue *tx_queue,
789                                struct efx_tso_header *tsoh, unsigned len)
790 {
791         struct efx_tx_buffer *buffer;
792
793         buffer = &tx_queue->buffer[tx_queue->insert_count &
794                                    tx_queue->efx->type->txd_ring_mask];
795         efx_tsoh_free(tx_queue, buffer);
796         EFX_BUG_ON_PARANOID(buffer->len);
797         EFX_BUG_ON_PARANOID(buffer->unmap_len);
798         EFX_BUG_ON_PARANOID(buffer->skb);
799         EFX_BUG_ON_PARANOID(!buffer->continuation);
800         EFX_BUG_ON_PARANOID(buffer->tsoh);
801         buffer->len = len;
802         buffer->dma_addr = tsoh->dma_addr;
803         buffer->tsoh = tsoh;
804
805         ++tx_queue->insert_count;
806 }
807
808
809 /* Remove descriptors put into a tx_queue. */
810 static void efx_enqueue_unwind(struct efx_tx_queue *tx_queue)
811 {
812         struct efx_tx_buffer *buffer;
813         dma_addr_t unmap_addr;
814
815         /* Work backwards until we hit the original insert pointer value */
816         while (tx_queue->insert_count != tx_queue->write_count) {
817                 --tx_queue->insert_count;
818                 buffer = &tx_queue->buffer[tx_queue->insert_count &
819                                            tx_queue->efx->type->txd_ring_mask];
820                 efx_tsoh_free(tx_queue, buffer);
821                 EFX_BUG_ON_PARANOID(buffer->skb);
822                 buffer->len = 0;
823                 buffer->continuation = true;
824                 if (buffer->unmap_len) {
825                         unmap_addr = (buffer->dma_addr + buffer->len -
826                                       buffer->unmap_len);
827                         if (buffer->unmap_single)
828                                 pci_unmap_single(tx_queue->efx->pci_dev,
829                                                  unmap_addr, buffer->unmap_len,
830                                                  PCI_DMA_TODEVICE);
831                         else
832                                 pci_unmap_page(tx_queue->efx->pci_dev,
833                                                unmap_addr, buffer->unmap_len,
834                                                PCI_DMA_TODEVICE);
835                         buffer->unmap_len = 0;
836                 }
837         }
838 }
839
840
841 /* Parse the SKB header and initialise state. */
842 static void tso_start(struct tso_state *st, const struct sk_buff *skb)
843 {
844         /* All ethernet/IP/TCP headers combined size is TCP header size
845          * plus offset of TCP header relative to start of packet.
846          */
847         st->header_len = ((tcp_hdr(skb)->doff << 2u)
848                           + PTR_DIFF(tcp_hdr(skb), skb->data));
849         st->full_packet_size = st->header_len + skb_shinfo(skb)->gso_size;
850
851         st->ipv4_id = ntohs(ip_hdr(skb)->id);
852         st->seqnum = ntohl(tcp_hdr(skb)->seq);
853
854         EFX_BUG_ON_PARANOID(tcp_hdr(skb)->urg);
855         EFX_BUG_ON_PARANOID(tcp_hdr(skb)->syn);
856         EFX_BUG_ON_PARANOID(tcp_hdr(skb)->rst);
857
858         st->packet_space = st->full_packet_size;
859         st->out_len = skb->len - st->header_len;
860         st->unmap_len = 0;
861         st->unmap_single = false;
862 }
863
864 static int tso_get_fragment(struct tso_state *st, struct efx_nic *efx,
865                             skb_frag_t *frag)
866 {
867         st->unmap_addr = pci_map_page(efx->pci_dev, frag->page,
868                                       frag->page_offset, frag->size,
869                                       PCI_DMA_TODEVICE);
870         if (likely(!pci_dma_mapping_error(efx->pci_dev, st->unmap_addr))) {
871                 st->unmap_single = false;
872                 st->unmap_len = frag->size;
873                 st->in_len = frag->size;
874                 st->dma_addr = st->unmap_addr;
875                 return 0;
876         }
877         return -ENOMEM;
878 }
879
880 static int tso_get_head_fragment(struct tso_state *st, struct efx_nic *efx,
881                                  const struct sk_buff *skb)
882 {
883         int hl = st->header_len;
884         int len = skb_headlen(skb) - hl;
885
886         st->unmap_addr = pci_map_single(efx->pci_dev, skb->data + hl,
887                                         len, PCI_DMA_TODEVICE);
888         if (likely(!pci_dma_mapping_error(efx->pci_dev, st->unmap_addr))) {
889                 st->unmap_single = true;
890                 st->unmap_len = len;
891                 st->in_len = len;
892                 st->dma_addr = st->unmap_addr;
893                 return 0;
894         }
895         return -ENOMEM;
896 }
897
898
899 /**
900  * tso_fill_packet_with_fragment - form descriptors for the current fragment
901  * @tx_queue:           Efx TX queue
902  * @skb:                Socket buffer
903  * @st:                 TSO state
904  *
905  * Form descriptors for the current fragment, until we reach the end
906  * of fragment or end-of-packet.  Return 0 on success, 1 if not enough
907  * space in @tx_queue.
908  */
909 static int tso_fill_packet_with_fragment(struct efx_tx_queue *tx_queue,
910                                          const struct sk_buff *skb,
911                                          struct tso_state *st)
912 {
913         struct efx_tx_buffer *buffer;
914         int n, end_of_packet, rc;
915
916         if (st->in_len == 0)
917                 return 0;
918         if (st->packet_space == 0)
919                 return 0;
920
921         EFX_BUG_ON_PARANOID(st->in_len <= 0);
922         EFX_BUG_ON_PARANOID(st->packet_space <= 0);
923
924         n = min(st->in_len, st->packet_space);
925
926         st->packet_space -= n;
927         st->out_len -= n;
928         st->in_len -= n;
929
930         rc = efx_tx_queue_insert(tx_queue, st->dma_addr, n, &buffer);
931         if (likely(rc == 0)) {
932                 if (st->out_len == 0)
933                         /* Transfer ownership of the skb */
934                         buffer->skb = skb;
935
936                 end_of_packet = st->out_len == 0 || st->packet_space == 0;
937                 buffer->continuation = !end_of_packet;
938
939                 if (st->in_len == 0) {
940                         /* Transfer ownership of the pci mapping */
941                         buffer->unmap_len = st->unmap_len;
942                         buffer->unmap_single = st->unmap_single;
943                         st->unmap_len = 0;
944                 }
945         }
946
947         st->dma_addr += n;
948         return rc;
949 }
950
951
952 /**
953  * tso_start_new_packet - generate a new header and prepare for the new packet
954  * @tx_queue:           Efx TX queue
955  * @skb:                Socket buffer
956  * @st:                 TSO state
957  *
958  * Generate a new header and prepare for the new packet.  Return 0 on
959  * success, or -1 if failed to alloc header.
960  */
961 static int tso_start_new_packet(struct efx_tx_queue *tx_queue,
962                                 const struct sk_buff *skb,
963                                 struct tso_state *st)
964 {
965         struct efx_tso_header *tsoh;
966         struct iphdr *tsoh_iph;
967         struct tcphdr *tsoh_th;
968         unsigned ip_length;
969         u8 *header;
970
971         /* Allocate a DMA-mapped header buffer. */
972         if (likely(TSOH_SIZE(st->header_len) <= TSOH_STD_SIZE)) {
973                 if (tx_queue->tso_headers_free == NULL) {
974                         if (efx_tsoh_block_alloc(tx_queue))
975                                 return -1;
976                 }
977                 EFX_BUG_ON_PARANOID(!tx_queue->tso_headers_free);
978                 tsoh = tx_queue->tso_headers_free;
979                 tx_queue->tso_headers_free = tsoh->next;
980                 tsoh->unmap_len = 0;
981         } else {
982                 tx_queue->tso_long_headers++;
983                 tsoh = efx_tsoh_heap_alloc(tx_queue, st->header_len);
984                 if (unlikely(!tsoh))
985                         return -1;
986         }
987
988         header = TSOH_BUFFER(tsoh);
989         tsoh_th = (struct tcphdr *)(header + SKB_TCP_OFF(skb));
990         tsoh_iph = (struct iphdr *)(header + SKB_IPV4_OFF(skb));
991
992         /* Copy and update the headers. */
993         memcpy(header, skb->data, st->header_len);
994
995         tsoh_th->seq = htonl(st->seqnum);
996         st->seqnum += skb_shinfo(skb)->gso_size;
997         if (st->out_len > skb_shinfo(skb)->gso_size) {
998                 /* This packet will not finish the TSO burst. */
999                 ip_length = st->full_packet_size - ETH_HDR_LEN(skb);
1000                 tsoh_th->fin = 0;
1001                 tsoh_th->psh = 0;
1002         } else {
1003                 /* This packet will be the last in the TSO burst. */
1004                 ip_length = st->header_len - ETH_HDR_LEN(skb) + st->out_len;
1005                 tsoh_th->fin = tcp_hdr(skb)->fin;
1006                 tsoh_th->psh = tcp_hdr(skb)->psh;
1007         }
1008         tsoh_iph->tot_len = htons(ip_length);
1009
1010         /* Linux leaves suitable gaps in the IP ID space for us to fill. */
1011         tsoh_iph->id = htons(st->ipv4_id);
1012         st->ipv4_id++;
1013
1014         st->packet_space = skb_shinfo(skb)->gso_size;
1015         ++tx_queue->tso_packets;
1016
1017         /* Form a descriptor for this header. */
1018         efx_tso_put_header(tx_queue, tsoh, st->header_len);
1019
1020         return 0;
1021 }
1022
1023
1024 /**
1025  * efx_enqueue_skb_tso - segment and transmit a TSO socket buffer
1026  * @tx_queue:           Efx TX queue
1027  * @skb:                Socket buffer
1028  *
1029  * Context: You must hold netif_tx_lock() to call this function.
1030  *
1031  * Add socket buffer @skb to @tx_queue, doing TSO or return != 0 if
1032  * @skb was not enqueued.  In all cases @skb is consumed.  Return
1033  * %NETDEV_TX_OK or %NETDEV_TX_BUSY.
1034  */
1035 static int efx_enqueue_skb_tso(struct efx_tx_queue *tx_queue,
1036                                struct sk_buff *skb)
1037 {
1038         struct efx_nic *efx = tx_queue->efx;
1039         int frag_i, rc, rc2 = NETDEV_TX_OK;
1040         struct tso_state state;
1041
1042         /* Verify TSO is safe - these checks should never fail. */
1043         efx_tso_check_safe(skb);
1044
1045         EFX_BUG_ON_PARANOID(tx_queue->write_count != tx_queue->insert_count);
1046
1047         tso_start(&state, skb);
1048
1049         /* Assume that skb header area contains exactly the headers, and
1050          * all payload is in the frag list.
1051          */
1052         if (skb_headlen(skb) == state.header_len) {
1053                 /* Grab the first payload fragment. */
1054                 EFX_BUG_ON_PARANOID(skb_shinfo(skb)->nr_frags < 1);
1055                 frag_i = 0;
1056                 rc = tso_get_fragment(&state, efx,
1057                                       skb_shinfo(skb)->frags + frag_i);
1058                 if (rc)
1059                         goto mem_err;
1060         } else {
1061                 rc = tso_get_head_fragment(&state, efx, skb);
1062                 if (rc)
1063                         goto mem_err;
1064                 frag_i = -1;
1065         }
1066
1067         if (tso_start_new_packet(tx_queue, skb, &state) < 0)
1068                 goto mem_err;
1069
1070         while (1) {
1071                 rc = tso_fill_packet_with_fragment(tx_queue, skb, &state);
1072                 if (unlikely(rc))
1073                         goto stop;
1074
1075                 /* Move onto the next fragment? */
1076                 if (state.in_len == 0) {
1077                         if (++frag_i >= skb_shinfo(skb)->nr_frags)
1078                                 /* End of payload reached. */
1079                                 break;
1080                         rc = tso_get_fragment(&state, efx,
1081                                               skb_shinfo(skb)->frags + frag_i);
1082                         if (rc)
1083                                 goto mem_err;
1084                 }
1085
1086                 /* Start at new packet? */
1087                 if (state.packet_space == 0 &&
1088                     tso_start_new_packet(tx_queue, skb, &state) < 0)
1089                         goto mem_err;
1090         }
1091
1092         /* Pass off to hardware */
1093         falcon_push_buffers(tx_queue);
1094
1095         tx_queue->tso_bursts++;
1096         return NETDEV_TX_OK;
1097
1098  mem_err:
1099         EFX_ERR(efx, "Out of memory for TSO headers, or PCI mapping error\n");
1100         dev_kfree_skb_any((struct sk_buff *)skb);
1101         goto unwind;
1102
1103  stop:
1104         rc2 = NETDEV_TX_BUSY;
1105
1106         /* Stop the queue if it wasn't stopped before. */
1107         if (tx_queue->stopped == 1)
1108                 efx_stop_queue(efx);
1109
1110  unwind:
1111         /* Free the DMA mapping we were in the process of writing out */
1112         if (state.unmap_len) {
1113                 if (state.unmap_single)
1114                         pci_unmap_single(efx->pci_dev, state.unmap_addr,
1115                                          state.unmap_len, PCI_DMA_TODEVICE);
1116                 else
1117                         pci_unmap_page(efx->pci_dev, state.unmap_addr,
1118                                        state.unmap_len, PCI_DMA_TODEVICE);
1119         }
1120
1121         efx_enqueue_unwind(tx_queue);
1122         return rc2;
1123 }
1124
1125
1126 /*
1127  * Free up all TSO datastructures associated with tx_queue. This
1128  * routine should be called only once the tx_queue is both empty and
1129  * will no longer be used.
1130  */
1131 static void efx_fini_tso(struct efx_tx_queue *tx_queue)
1132 {
1133         unsigned i;
1134
1135         if (tx_queue->buffer) {
1136                 for (i = 0; i <= tx_queue->efx->type->txd_ring_mask; ++i)
1137                         efx_tsoh_free(tx_queue, &tx_queue->buffer[i]);
1138         }
1139
1140         while (tx_queue->tso_headers_free != NULL)
1141                 efx_tsoh_block_free(tx_queue, tx_queue->tso_headers_free,
1142                                     tx_queue->efx->pci_dev);
1143 }