1// SPDX-License-Identifier: GPL-2.0
2
3/* Copyright (c) 2012-2018, The Linux Foundation. All rights reserved.
4 * Copyright (C) 2019-2024 Linaro Ltd.
5 */
6
7#include <linux/bitfield.h>
8#include <linux/bits.h>
9#include <linux/dma-direction.h>
10#include <linux/refcount.h>
11#include <linux/scatterlist.h>
12#include <linux/types.h>
13
14#include "gsi.h"
15#include "gsi_private.h"
16#include "gsi_trans.h"
17#include "ipa_cmd.h"
18#include "ipa_data.h"
19#include "ipa_gsi.h"
20
21/**
22 * DOC: GSI Transactions
23 *
24 * A GSI transaction abstracts the behavior of a GSI channel by representing
25 * everything about a related group of IPA operations in a single structure.
26 * (A "operation" in this sense is either a data transfer or an IPA immediate
27 * command.) Most details of interaction with the GSI hardware are managed
28 * by the GSI transaction core, allowing users to simply describe operations
29 * to be performed. When a transaction has completed a callback function
30 * (dependent on the type of endpoint associated with the channel) allows
31 * cleanup of resources associated with the transaction.
32 *
33 * To perform an operation (or set of them), a user of the GSI transaction
34 * interface allocates a transaction, indicating the number of TREs required
35 * (one per operation). If sufficient TREs are available, they are reserved
36 * for use in the transaction and the allocation succeeds. This way
37 * exhaustion of the available TREs in a channel ring is detected as early
38 * as possible. Any other resources that might be needed to complete a
39 * transaction are also allocated when the transaction is allocated.
40 *
41 * Operations performed as part of a transaction are represented in an array
42 * of Linux scatterlist structures, allocated with the transaction. These
43 * scatterlist structures are initialized by "adding" operations to the
44 * transaction. If a buffer in an operation must be mapped for DMA, this is
45 * done at the time it is added to the transaction. It is possible for a
46 * mapping error to occur when an operation is added. In this case the
47 * transaction should simply be freed; this correctly releases resources
48 * associated with the transaction.
49 *
50 * Once all operations have been successfully added to a transaction, the
51 * transaction is committed. Committing transfers ownership of the entire
52 * transaction to the GSI transaction core. The GSI transaction code
53 * formats the content of the scatterlist array into the channel ring
54 * buffer and informs the hardware that new TREs are available to process.
55 *
56 * The last TRE in each transaction is marked to interrupt the AP when the
57 * GSI hardware has completed it. Because transfers described by TREs are
58 * performed strictly in order, signaling the completion of just the last
59 * TRE in the transaction is sufficient to indicate the full transaction
60 * is complete.
61 *
62 * When a transaction is complete, ipa_gsi_trans_complete() is called by the
63 * GSI code into the IPA layer, allowing it to perform any final cleanup
64 * required before the transaction is freed.
65 */
66
67/* Hardware values representing a transfer element type */
68enum gsi_tre_type {
69 GSI_RE_XFER = 0x2,
70 GSI_RE_IMMD_CMD = 0x3,
71};
72
73/* An entry in a channel ring */
74struct gsi_tre {
75 __le64 addr; /* DMA address */
76 __le16 len_opcode; /* length in bytes or enum IPA_CMD_* */
77 __le16 reserved;
78 __le32 flags; /* TRE_FLAGS_* */
79};
80
81/* gsi_tre->flags mask values (in CPU byte order) */
82#define TRE_FLAGS_CHAIN_FMASK GENMASK(0, 0)
83#define TRE_FLAGS_IEOT_FMASK GENMASK(9, 9)
84#define TRE_FLAGS_BEI_FMASK GENMASK(10, 10)
85#define TRE_FLAGS_TYPE_FMASK GENMASK(23, 16)
86
87int gsi_trans_pool_init(struct gsi_trans_pool *pool, size_t size, u32 count,
88 u32 max_alloc)
89{
90 size_t alloc_size;
91 void *virt;
92
93 if (!size)
94 return -EINVAL;
95 if (count < max_alloc)
96 return -EINVAL;
97 if (!max_alloc)
98 return -EINVAL;
99
100 /* By allocating a few extra entries in our pool (one less
101 * than the maximum number that will be requested in a
102 * single allocation), we can always satisfy requests without
103 * ever worrying about straddling the end of the pool array.
104 * If there aren't enough entries starting at the free index,
105 * we just allocate free entries from the beginning of the pool.
106 */
107 alloc_size = size_mul(factor1: count + max_alloc - 1, factor2: size);
108 alloc_size = kmalloc_size_roundup(size: alloc_size);
109 virt = kzalloc(alloc_size, GFP_KERNEL);
110 if (!virt)
111 return -ENOMEM;
112
113 pool->base = virt;
114 /* If the allocator gave us any extra memory, use it */
115 pool->count = alloc_size / size;
116 pool->free = 0;
117 pool->max_alloc = max_alloc;
118 pool->size = size;
119 pool->addr = 0; /* Only used for DMA pools */
120
121 return 0;
122}
123
124void gsi_trans_pool_exit(struct gsi_trans_pool *pool)
125{
126 kfree(objp: pool->base);
127 memset(pool, 0, sizeof(*pool));
128}
129
130/* Home-grown DMA pool. This way we can preallocate the pool, and guarantee
131 * allocations will succeed. The immediate commands in a transaction can
132 * require up to max_alloc elements from the pool. But we only allow
133 * allocation of a single element from a DMA pool at a time.
134 */
135int gsi_trans_pool_init_dma(struct device *dev, struct gsi_trans_pool *pool,
136 size_t size, u32 count, u32 max_alloc)
137{
138 size_t total_size;
139 dma_addr_t addr;
140 void *virt;
141
142 if (!size)
143 return -EINVAL;
144 if (count < max_alloc)
145 return -EINVAL;
146 if (!max_alloc)
147 return -EINVAL;
148
149 /* Don't let allocations cross a power-of-two boundary */
150 size = __roundup_pow_of_two(n: size);
151 total_size = (count + max_alloc - 1) * size;
152
153 /* The allocator will give us a power-of-2 number of pages
154 * sufficient to satisfy our request. Round up our requested
155 * size to avoid any unused space in the allocation. This way
156 * gsi_trans_pool_exit_dma() can assume the total allocated
157 * size is exactly (count * size).
158 */
159 total_size = PAGE_SIZE << get_order(size: total_size);
160
161 virt = dma_alloc_coherent(dev, size: total_size, dma_handle: &addr, GFP_KERNEL);
162 if (!virt)
163 return -ENOMEM;
164
165 pool->base = virt;
166 pool->count = total_size / size;
167 pool->free = 0;
168 pool->size = size;
169 pool->max_alloc = max_alloc;
170 pool->addr = addr;
171
172 return 0;
173}
174
175void gsi_trans_pool_exit_dma(struct device *dev, struct gsi_trans_pool *pool)
176{
177 size_t total_size = pool->count * pool->size;
178
179 dma_free_coherent(dev, size: total_size, cpu_addr: pool->base, dma_handle: pool->addr);
180 memset(pool, 0, sizeof(*pool));
181}
182
183/* Return the byte offset of the next free entry in the pool */
184static u32 gsi_trans_pool_alloc_common(struct gsi_trans_pool *pool, u32 count)
185{
186 u32 offset;
187
188 WARN_ON(!count);
189 WARN_ON(count > pool->max_alloc);
190
191 /* Allocate from beginning if wrap would occur */
192 if (count > pool->count - pool->free)
193 pool->free = 0;
194
195 offset = pool->free * pool->size;
196 pool->free += count;
197 memset(pool->base + offset, 0, count * pool->size);
198
199 return offset;
200}
201
202/* Allocate a contiguous block of zeroed entries from a pool */
203void *gsi_trans_pool_alloc(struct gsi_trans_pool *pool, u32 count)
204{
205 return pool->base + gsi_trans_pool_alloc_common(pool, count);
206}
207
208/* Allocate a single zeroed entry from a DMA pool */
209void *gsi_trans_pool_alloc_dma(struct gsi_trans_pool *pool, dma_addr_t *addr)
210{
211 u32 offset = gsi_trans_pool_alloc_common(pool, count: 1);
212
213 *addr = pool->addr + offset;
214
215 return pool->base + offset;
216}
217
218/* Map a TRE ring entry index to the transaction it is associated with */
219static void gsi_trans_map(struct gsi_trans *trans, u32 index)
220{
221 struct gsi_channel *channel = &trans->gsi->channel[trans->channel_id];
222
223 /* The completion event will indicate the last TRE used */
224 index += trans->used_count - 1;
225
226 /* Note: index *must* be used modulo the ring count here */
227 channel->trans_info.map[index % channel->tre_ring.count] = trans;
228}
229
230/* Return the transaction mapped to a given ring entry */
231struct gsi_trans *
232gsi_channel_trans_mapped(struct gsi_channel *channel, u32 index)
233{
234 /* Note: index *must* be used modulo the ring count here */
235 return channel->trans_info.map[index % channel->tre_ring.count];
236}
237
238/* Return the oldest completed transaction for a channel (or null) */
239struct gsi_trans *gsi_channel_trans_complete(struct gsi_channel *channel)
240{
241 struct gsi_trans_info *trans_info = &channel->trans_info;
242 u16 trans_id = trans_info->completed_id;
243
244 if (trans_id == trans_info->pending_id) {
245 gsi_channel_update(channel);
246 if (trans_id == trans_info->pending_id)
247 return NULL;
248 }
249
250 return &trans_info->trans[trans_id %= channel->tre_count];
251}
252
253/* Move a transaction from allocated to committed state */
254static void gsi_trans_move_committed(struct gsi_trans *trans)
255{
256 struct gsi_channel *channel = &trans->gsi->channel[trans->channel_id];
257 struct gsi_trans_info *trans_info = &channel->trans_info;
258
259 /* This allocated transaction is now committed */
260 trans_info->allocated_id++;
261}
262
263/* Move committed transactions to pending state */
264static void gsi_trans_move_pending(struct gsi_trans *trans)
265{
266 struct gsi_channel *channel = &trans->gsi->channel[trans->channel_id];
267 struct gsi_trans_info *trans_info = &channel->trans_info;
268 u16 trans_index = trans - &trans_info->trans[0];
269 u16 delta;
270
271 /* These committed transactions are now pending */
272 delta = trans_index - trans_info->committed_id + 1;
273 trans_info->committed_id += delta % channel->tre_count;
274}
275
276/* Move pending transactions to completed state */
277void gsi_trans_move_complete(struct gsi_trans *trans)
278{
279 struct gsi_channel *channel = &trans->gsi->channel[trans->channel_id];
280 struct gsi_trans_info *trans_info = &channel->trans_info;
281 u16 trans_index = trans - trans_info->trans;
282 u16 delta;
283
284 /* These pending transactions are now completed */
285 delta = trans_index - trans_info->pending_id + 1;
286 delta %= channel->tre_count;
287 trans_info->pending_id += delta;
288}
289
290/* Move a transaction from completed to polled state */
291void gsi_trans_move_polled(struct gsi_trans *trans)
292{
293 struct gsi_channel *channel = &trans->gsi->channel[trans->channel_id];
294 struct gsi_trans_info *trans_info = &channel->trans_info;
295
296 /* This completed transaction is now polled */
297 trans_info->completed_id++;
298}
299
300/* Reserve some number of TREs on a channel. Returns true if successful */
301static bool
302gsi_trans_tre_reserve(struct gsi_trans_info *trans_info, u32 tre_count)
303{
304 int avail = atomic_read(v: &trans_info->tre_avail);
305 int new;
306
307 do {
308 new = avail - (int)tre_count;
309 if (unlikely(new < 0))
310 return false;
311 } while (!atomic_try_cmpxchg(v: &trans_info->tre_avail, old: &avail, new));
312
313 return true;
314}
315
316/* Release previously-reserved TRE entries to a channel */
317static void
318gsi_trans_tre_release(struct gsi_trans_info *trans_info, u32 tre_count)
319{
320 atomic_add(i: tre_count, v: &trans_info->tre_avail);
321}
322
323/* Return true if no transactions are allocated, false otherwise */
324bool gsi_channel_trans_idle(struct gsi *gsi, u32 channel_id)
325{
326 u32 tre_max = gsi_channel_tre_max(gsi, channel_id);
327 struct gsi_trans_info *trans_info;
328
329 trans_info = &gsi->channel[channel_id].trans_info;
330
331 return atomic_read(v: &trans_info->tre_avail) == tre_max;
332}
333
334/* Allocate a GSI transaction on a channel */
335struct gsi_trans *gsi_channel_trans_alloc(struct gsi *gsi, u32 channel_id,
336 u32 tre_count,
337 enum dma_data_direction direction)
338{
339 struct gsi_channel *channel = &gsi->channel[channel_id];
340 struct gsi_trans_info *trans_info;
341 struct gsi_trans *trans;
342 u16 trans_index;
343
344 if (WARN_ON(tre_count > channel->trans_tre_max))
345 return NULL;
346
347 trans_info = &channel->trans_info;
348
349 /* If we can't reserve the TREs for the transaction, we're done */
350 if (!gsi_trans_tre_reserve(trans_info, tre_count))
351 return NULL;
352
353 trans_index = trans_info->free_id % channel->tre_count;
354 trans = &trans_info->trans[trans_index];
355 memset(trans, 0, sizeof(*trans));
356
357 /* Initialize non-zero fields in the transaction */
358 trans->gsi = gsi;
359 trans->channel_id = channel_id;
360 trans->rsvd_count = tre_count;
361 init_completion(x: &trans->completion);
362
363 /* Allocate the scatterlist */
364 trans->sgl = gsi_trans_pool_alloc(pool: &trans_info->sg_pool, count: tre_count);
365 sg_init_marker(sgl: trans->sgl, nents: tre_count);
366
367 trans->direction = direction;
368 refcount_set(r: &trans->refcount, n: 1);
369
370 /* This free transaction is now allocated */
371 trans_info->free_id++;
372
373 return trans;
374}
375
376/* Free a previously-allocated transaction */
377void gsi_trans_free(struct gsi_trans *trans)
378{
379 struct gsi_trans_info *trans_info;
380
381 if (!refcount_dec_and_test(r: &trans->refcount))
382 return;
383
384 /* Unused transactions are allocated but never committed, pending,
385 * completed, or polled.
386 */
387 trans_info = &trans->gsi->channel[trans->channel_id].trans_info;
388 if (!trans->used_count) {
389 trans_info->allocated_id++;
390 trans_info->committed_id++;
391 trans_info->pending_id++;
392 trans_info->completed_id++;
393 } else {
394 ipa_gsi_trans_release(trans);
395 }
396
397 /* This transaction is now free */
398 trans_info->polled_id++;
399
400 /* Releasing the reserved TREs implicitly frees the sgl[] and
401 * (if present) info[] arrays, plus the transaction itself.
402 */
403 gsi_trans_tre_release(trans_info, tre_count: trans->rsvd_count);
404}
405
406/* Add an immediate command to a transaction */
407void gsi_trans_cmd_add(struct gsi_trans *trans, void *buf, u32 size,
408 dma_addr_t addr, enum ipa_cmd_opcode opcode)
409{
410 u32 which = trans->used_count++;
411 struct scatterlist *sg;
412
413 WARN_ON(which >= trans->rsvd_count);
414
415 /* Commands are quite different from data transfer requests.
416 * Their payloads come from a pool whose memory is allocated
417 * using dma_alloc_coherent(). We therefore do *not* map them
418 * for DMA (unlike what we do for pages and skbs).
419 *
420 * When a transaction completes, the SGL is normally unmapped.
421 * A command transaction has direction DMA_NONE, which tells
422 * gsi_trans_complete() to skip the unmapping step.
423 *
424 * The only things we use directly in a command scatter/gather
425 * entry are the DMA address and length. We still need the SG
426 * table flags to be maintained though, so assign a NULL page
427 * pointer for that purpose.
428 */
429 sg = &trans->sgl[which];
430 sg_assign_page(sg, NULL);
431 sg_dma_address(sg) = addr;
432 sg_dma_len(sg) = size;
433
434 trans->cmd_opcode[which] = opcode;
435}
436
437/* Add a page transfer to a transaction. It will fill the only TRE. */
438int gsi_trans_page_add(struct gsi_trans *trans, struct page *page, u32 size,
439 u32 offset)
440{
441 struct scatterlist *sg = &trans->sgl[0];
442 int ret;
443
444 if (WARN_ON(trans->rsvd_count != 1))
445 return -EINVAL;
446 if (WARN_ON(trans->used_count))
447 return -EINVAL;
448
449 sg_set_page(sg, page, len: size, offset);
450 ret = dma_map_sg(trans->gsi->dev, sg, 1, trans->direction);
451 if (!ret)
452 return -ENOMEM;
453
454 trans->used_count++; /* Transaction now owns the (DMA mapped) page */
455
456 return 0;
457}
458
459/* Add an SKB transfer to a transaction. No other TREs will be used. */
460int gsi_trans_skb_add(struct gsi_trans *trans, struct sk_buff *skb)
461{
462 struct scatterlist *sg = &trans->sgl[0];
463 u32 used_count;
464 int ret;
465
466 if (WARN_ON(trans->rsvd_count != 1))
467 return -EINVAL;
468 if (WARN_ON(trans->used_count))
469 return -EINVAL;
470
471 /* skb->len will not be 0 (checked early) */
472 ret = skb_to_sgvec(skb, sg, offset: 0, len: skb->len);
473 if (ret < 0)
474 return ret;
475 used_count = ret;
476
477 ret = dma_map_sg(trans->gsi->dev, sg, used_count, trans->direction);
478 if (!ret)
479 return -ENOMEM;
480
481 /* Transaction now owns the (DMA mapped) skb */
482 trans->used_count += used_count;
483
484 return 0;
485}
486
487/* Compute the length/opcode value to use for a TRE */
488static __le16 gsi_tre_len_opcode(enum ipa_cmd_opcode opcode, u32 len)
489{
490 return opcode == IPA_CMD_NONE ? cpu_to_le16((u16)len)
491 : cpu_to_le16((u16)opcode);
492}
493
494/* Compute the flags value to use for a given TRE */
495static __le32 gsi_tre_flags(bool last_tre, bool bei, enum ipa_cmd_opcode opcode)
496{
497 enum gsi_tre_type tre_type;
498 u32 tre_flags;
499
500 tre_type = opcode == IPA_CMD_NONE ? GSI_RE_XFER : GSI_RE_IMMD_CMD;
501 tre_flags = u32_encode_bits(v: tre_type, TRE_FLAGS_TYPE_FMASK);
502
503 /* Last TRE contains interrupt flags */
504 if (last_tre) {
505 /* All transactions end in a transfer completion interrupt */
506 tre_flags |= TRE_FLAGS_IEOT_FMASK;
507 /* Don't interrupt when outbound commands are acknowledged */
508 if (bei)
509 tre_flags |= TRE_FLAGS_BEI_FMASK;
510 } else { /* All others indicate there's more to come */
511 tre_flags |= TRE_FLAGS_CHAIN_FMASK;
512 }
513
514 return cpu_to_le32(tre_flags);
515}
516
517static void gsi_trans_tre_fill(struct gsi_tre *dest_tre, dma_addr_t addr,
518 u32 len, bool last_tre, bool bei,
519 enum ipa_cmd_opcode opcode)
520{
521 struct gsi_tre tre;
522
523 tre.addr = cpu_to_le64(addr);
524 tre.len_opcode = gsi_tre_len_opcode(opcode, len);
525 tre.reserved = 0;
526 tre.flags = gsi_tre_flags(last_tre, bei, opcode);
527
528 /* ARM64 can write 16 bytes as a unit with a single instruction.
529 * Doing the assignment this way is an attempt to make that happen.
530 */
531 *dest_tre = tre;
532}
533
534/**
535 * __gsi_trans_commit() - Common GSI transaction commit code
536 * @trans: Transaction to commit
537 * @ring_db: Whether to tell the hardware about these queued transfers
538 *
539 * Formats channel ring TRE entries based on the content of the scatterlist.
540 * Maps a transaction pointer to the last ring entry used for the transaction,
541 * so it can be recovered when it completes. Moves the transaction to
542 * pending state. Finally, updates the channel ring pointer and optionally
543 * rings the doorbell.
544 */
545static void __gsi_trans_commit(struct gsi_trans *trans, bool ring_db)
546{
547 struct gsi_channel *channel = &trans->gsi->channel[trans->channel_id];
548 struct gsi_ring *tre_ring = &channel->tre_ring;
549 enum ipa_cmd_opcode opcode = IPA_CMD_NONE;
550 bool bei = channel->toward_ipa;
551 struct gsi_tre *dest_tre;
552 struct scatterlist *sg;
553 u32 byte_count = 0;
554 u8 *cmd_opcode;
555 u32 avail;
556 u32 i;
557
558 WARN_ON(!trans->used_count);
559
560 /* Consume the entries. If we cross the end of the ring while
561 * filling them we'll switch to the beginning to finish.
562 * If there is no info array we're doing a simple data
563 * transfer request, whose opcode is IPA_CMD_NONE.
564 */
565 cmd_opcode = channel->command ? &trans->cmd_opcode[0] : NULL;
566 avail = tre_ring->count - tre_ring->index % tre_ring->count;
567 dest_tre = gsi_ring_virt(ring: tre_ring, index: tre_ring->index);
568 for_each_sg(trans->sgl, sg, trans->used_count, i) {
569 bool last_tre = i == trans->used_count - 1;
570 dma_addr_t addr = sg_dma_address(sg);
571 u32 len = sg_dma_len(sg);
572
573 byte_count += len;
574 if (!avail--)
575 dest_tre = gsi_ring_virt(ring: tre_ring, index: 0);
576 if (cmd_opcode)
577 opcode = *cmd_opcode++;
578
579 gsi_trans_tre_fill(dest_tre, addr, len, last_tre, bei, opcode);
580 dest_tre++;
581 }
582 /* Associate the TRE with the transaction */
583 gsi_trans_map(trans, index: tre_ring->index);
584
585 tre_ring->index += trans->used_count;
586
587 trans->len = byte_count;
588 if (channel->toward_ipa)
589 gsi_trans_tx_committed(trans);
590
591 gsi_trans_move_committed(trans);
592
593 /* Ring doorbell if requested, or if all TREs are allocated */
594 if (ring_db || !atomic_read(v: &channel->trans_info.tre_avail)) {
595 /* Report what we're handing off to hardware for TX channels */
596 if (channel->toward_ipa)
597 gsi_trans_tx_queued(trans);
598 gsi_trans_move_pending(trans);
599 gsi_channel_doorbell(channel);
600 }
601}
602
603/* Commit a GSI transaction */
604void gsi_trans_commit(struct gsi_trans *trans, bool ring_db)
605{
606 if (trans->used_count)
607 __gsi_trans_commit(trans, ring_db);
608 else
609 gsi_trans_free(trans);
610}
611
612/* Commit a GSI transaction and wait for it to complete */
613void gsi_trans_commit_wait(struct gsi_trans *trans)
614{
615 if (!trans->used_count)
616 goto out_trans_free;
617
618 refcount_inc(r: &trans->refcount);
619
620 __gsi_trans_commit(trans, ring_db: true);
621
622 wait_for_completion(&trans->completion);
623
624out_trans_free:
625 gsi_trans_free(trans);
626}
627
628/* Process the completion of a transaction; called while polling */
629void gsi_trans_complete(struct gsi_trans *trans)
630{
631 /* If the entire SGL was mapped when added, unmap it now */
632 if (trans->direction != DMA_NONE)
633 dma_unmap_sg(trans->gsi->dev, trans->sgl, trans->used_count,
634 trans->direction);
635
636 ipa_gsi_trans_complete(trans);
637
638 complete(&trans->completion);
639
640 gsi_trans_free(trans);
641}
642
643/* Cancel a channel's pending transactions */
644void gsi_channel_trans_cancel_pending(struct gsi_channel *channel)
645{
646 struct gsi_trans_info *trans_info = &channel->trans_info;
647 u16 trans_id = trans_info->pending_id;
648
649 /* channel->gsi->mutex is held by caller */
650
651 /* If there are no pending transactions, we're done */
652 if (trans_id == trans_info->committed_id)
653 return;
654
655 /* Mark all pending transactions cancelled */
656 do {
657 struct gsi_trans *trans;
658
659 trans = &trans_info->trans[trans_id % channel->tre_count];
660 trans->cancelled = true;
661 } while (++trans_id != trans_info->committed_id);
662
663 /* All pending transactions are now completed */
664 trans_info->pending_id = trans_info->committed_id;
665
666 /* Schedule NAPI polling to complete the cancelled transactions */
667 napi_schedule(n: &channel->napi);
668}
669
670/* Issue a command to read a single byte from a channel */
671int gsi_trans_read_byte(struct gsi *gsi, u32 channel_id, dma_addr_t addr)
672{
673 struct gsi_channel *channel = &gsi->channel[channel_id];
674 struct gsi_ring *tre_ring = &channel->tre_ring;
675 struct gsi_trans_info *trans_info;
676 struct gsi_tre *dest_tre;
677
678 trans_info = &channel->trans_info;
679
680 /* First reserve the TRE, if possible */
681 if (!gsi_trans_tre_reserve(trans_info, tre_count: 1))
682 return -EBUSY;
683
684 /* Now fill the reserved TRE and tell the hardware */
685
686 dest_tre = gsi_ring_virt(ring: tre_ring, index: tre_ring->index);
687 gsi_trans_tre_fill(dest_tre, addr, len: 1, last_tre: true, bei: false, opcode: IPA_CMD_NONE);
688
689 tre_ring->index++;
690 gsi_channel_doorbell(channel);
691
692 return 0;
693}
694
695/* Mark a gsi_trans_read_byte() request done */
696void gsi_trans_read_byte_done(struct gsi *gsi, u32 channel_id)
697{
698 struct gsi_channel *channel = &gsi->channel[channel_id];
699
700 gsi_trans_tre_release(trans_info: &channel->trans_info, tre_count: 1);
701}
702
703/* Initialize a channel's GSI transaction info */
704int gsi_channel_trans_init(struct gsi *gsi, u32 channel_id)
705{
706 struct gsi_channel *channel = &gsi->channel[channel_id];
707 u32 tre_count = channel->tre_count;
708 struct gsi_trans_info *trans_info;
709 u32 tre_max;
710 int ret;
711
712 /* Ensure the size of a channel element is what's expected */
713 BUILD_BUG_ON(sizeof(struct gsi_tre) != GSI_RING_ELEMENT_SIZE);
714
715 trans_info = &channel->trans_info;
716
717 /* The tre_avail field is what ultimately limits the number of
718 * outstanding transactions and their resources. A transaction
719 * allocation succeeds only if the TREs available are sufficient
720 * for what the transaction might need.
721 */
722 tre_max = gsi_channel_tre_max(gsi: channel->gsi, channel_id);
723 atomic_set(v: &trans_info->tre_avail, i: tre_max);
724
725 /* We can't use more TREs than the number available in the ring.
726 * This limits the number of transactions that can be outstanding.
727 * Worst case is one TRE per transaction (but we actually limit
728 * it to something a little less than that). By allocating a
729 * power-of-two number of transactions we can use an index
730 * modulo that number to determine the next one that's free.
731 * Transactions are allocated one at a time.
732 */
733 trans_info->trans = kcalloc(tre_count, sizeof(*trans_info->trans),
734 GFP_KERNEL);
735 if (!trans_info->trans)
736 return -ENOMEM;
737 trans_info->free_id = 0; /* all modulo channel->tre_count */
738 trans_info->allocated_id = 0;
739 trans_info->committed_id = 0;
740 trans_info->pending_id = 0;
741 trans_info->completed_id = 0;
742 trans_info->polled_id = 0;
743
744 /* A completion event contains a pointer to the TRE that caused
745 * the event (which will be the last one used by the transaction).
746 * Each entry in this map records the transaction associated
747 * with a corresponding completed TRE.
748 */
749 trans_info->map = kcalloc(tre_count, sizeof(*trans_info->map),
750 GFP_KERNEL);
751 if (!trans_info->map) {
752 ret = -ENOMEM;
753 goto err_trans_free;
754 }
755
756 /* A transaction uses a scatterlist array to represent the data
757 * transfers implemented by the transaction. Each scatterlist
758 * element is used to fill a single TRE when the transaction is
759 * committed. So we need as many scatterlist elements as the
760 * maximum number of TREs that can be outstanding.
761 */
762 ret = gsi_trans_pool_init(pool: &trans_info->sg_pool,
763 size: sizeof(struct scatterlist),
764 count: tre_max, max_alloc: channel->trans_tre_max);
765 if (ret)
766 goto err_map_free;
767
768
769 return 0;
770
771err_map_free:
772 kfree(objp: trans_info->map);
773err_trans_free:
774 kfree(objp: trans_info->trans);
775
776 dev_err(gsi->dev, "error %d initializing channel %u transactions\n",
777 ret, channel_id);
778
779 return ret;
780}
781
782/* Inverse of gsi_channel_trans_init() */
783void gsi_channel_trans_exit(struct gsi_channel *channel)
784{
785 struct gsi_trans_info *trans_info = &channel->trans_info;
786
787 gsi_trans_pool_exit(pool: &trans_info->sg_pool);
788 kfree(objp: trans_info->trans);
789 kfree(objp: trans_info->map);
790}
791

source code of linux/drivers/net/ipa/gsi_trans.c