xref: /linux/drivers/net/ipa/gsi_trans.c (revision 621cde16e49b3ecf7d59a8106a20aaebfb4a59a9)
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 */
68 enum gsi_tre_type {
69 	GSI_RE_XFER	= 0x2,
70 	GSI_RE_IMMD_CMD	= 0x3,
71 };
72 
73 /* An entry in a channel ring */
74 struct 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 
gsi_trans_pool_init(struct gsi_trans_pool * pool,size_t size,u32 count,u32 max_alloc)87 int 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(count + max_alloc - 1, size);
108 	alloc_size = kmalloc_size_roundup(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 
gsi_trans_pool_exit(struct gsi_trans_pool * pool)124 void gsi_trans_pool_exit(struct gsi_trans_pool *pool)
125 {
126 	kfree(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  */
gsi_trans_pool_init_dma(struct device * dev,struct gsi_trans_pool * pool,size_t size,u32 count,u32 max_alloc)135 int 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(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(total_size);
160 
161 	virt = dma_alloc_coherent(dev, total_size, &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 
gsi_trans_pool_exit_dma(struct device * dev,struct gsi_trans_pool * pool)175 void 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, total_size, pool->base, pool->addr);
180 	memset(pool, 0, sizeof(*pool));
181 }
182 
183 /* Return the byte offset of the next free entry in the pool */
gsi_trans_pool_alloc_common(struct gsi_trans_pool * pool,u32 count)184 static 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 */
gsi_trans_pool_alloc(struct gsi_trans_pool * pool,u32 count)203 void *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 */
gsi_trans_pool_alloc_dma(struct gsi_trans_pool * pool,dma_addr_t * addr)209 void *gsi_trans_pool_alloc_dma(struct gsi_trans_pool *pool, dma_addr_t *addr)
210 {
211 	u32 offset = gsi_trans_pool_alloc_common(pool, 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 */
gsi_trans_map(struct gsi_trans * trans,u32 index)219 static 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 */
231 struct gsi_trans *
gsi_channel_trans_mapped(struct gsi_channel * channel,u32 index)232 gsi_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) */
gsi_channel_trans_complete(struct gsi_channel * channel)239 struct 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 */
gsi_trans_move_committed(struct gsi_trans * trans)254 static 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 */
gsi_trans_move_pending(struct gsi_trans * trans)264 static 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 */
gsi_trans_move_complete(struct gsi_trans * trans)277 void 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 */
gsi_trans_move_polled(struct gsi_trans * trans)291 void 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 */
301 static bool
gsi_trans_tre_reserve(struct gsi_trans_info * trans_info,u32 tre_count)302 gsi_trans_tre_reserve(struct gsi_trans_info *trans_info, u32 tre_count)
303 {
304 	int avail = atomic_read(&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(&trans_info->tre_avail, &avail, new));
312 
313 	return true;
314 }
315 
316 /* Release previously-reserved TRE entries to a channel */
317 static void
gsi_trans_tre_release(struct gsi_trans_info * trans_info,u32 tre_count)318 gsi_trans_tre_release(struct gsi_trans_info *trans_info, u32 tre_count)
319 {
320 	atomic_add(tre_count, &trans_info->tre_avail);
321 }
322 
323 /* Return true if no transactions are allocated, false otherwise */
gsi_channel_trans_idle(struct gsi * gsi,u32 channel_id)324 bool 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(&trans_info->tre_avail) == tre_max;
332 }
333 
334 /* Allocate a GSI transaction on a channel */
gsi_channel_trans_alloc(struct gsi * gsi,u32 channel_id,u32 tre_count,enum dma_data_direction direction)335 struct 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(&trans->completion);
362 
363 	/* Allocate the scatterlist */
364 	trans->sgl = gsi_trans_pool_alloc(&trans_info->sg_pool, tre_count);
365 	sg_init_marker(trans->sgl, tre_count);
366 
367 	trans->direction = direction;
368 	refcount_set(&trans->refcount, 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 */
gsi_trans_free(struct gsi_trans * trans)377 void gsi_trans_free(struct gsi_trans *trans)
378 {
379 	struct gsi_trans_info *trans_info;
380 
381 	if (!refcount_dec_and_test(&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, trans->rsvd_count);
404 }
405 
406 /* Add an immediate command to a transaction */
gsi_trans_cmd_add(struct gsi_trans * trans,void * buf,u32 size,dma_addr_t addr,enum ipa_cmd_opcode opcode)407 void 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. */
gsi_trans_page_add(struct gsi_trans * trans,struct page * page,u32 size,u32 offset)438 int 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, 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. */
gsi_trans_skb_add(struct gsi_trans * trans,struct sk_buff * skb)460 int 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, 0, 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 */
gsi_tre_len_opcode(enum ipa_cmd_opcode opcode,u32 len)488 static __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 */
gsi_tre_flags(bool last_tre,bool bei,enum ipa_cmd_opcode opcode)495 static __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(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 
gsi_trans_tre_fill(struct gsi_tre * dest_tre,dma_addr_t addr,u32 len,bool last_tre,bool bei,enum ipa_cmd_opcode opcode)517 static 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  */
__gsi_trans_commit(struct gsi_trans * trans,bool ring_db)545 static 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(tre_ring, 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(tre_ring, 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, 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(&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 */
gsi_trans_commit(struct gsi_trans * trans,bool ring_db)604 void 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 */
gsi_trans_commit_wait(struct gsi_trans * trans)613 void gsi_trans_commit_wait(struct gsi_trans *trans)
614 {
615 	if (!trans->used_count)
616 		goto out_trans_free;
617 
618 	refcount_inc(&trans->refcount);
619 
620 	__gsi_trans_commit(trans, true);
621 
622 	wait_for_completion(&trans->completion);
623 
624 out_trans_free:
625 	gsi_trans_free(trans);
626 }
627 
628 /* Process the completion of a transaction; called while polling */
gsi_trans_complete(struct gsi_trans * trans)629 void 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 */
gsi_channel_trans_cancel_pending(struct gsi_channel * channel)644 void 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(&channel->napi);
668 }
669 
670 /* Issue a command to read a single byte from a channel */
gsi_trans_read_byte(struct gsi * gsi,u32 channel_id,dma_addr_t addr)671 int 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, 1))
682 		return -EBUSY;
683 
684 	/* Now fill the reserved TRE and tell the hardware */
685 
686 	dest_tre = gsi_ring_virt(tre_ring, tre_ring->index);
687 	gsi_trans_tre_fill(dest_tre, addr, 1, true, false, 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 */
gsi_trans_read_byte_done(struct gsi * gsi,u32 channel_id)696 void 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(&channel->trans_info, 1);
701 }
702 
703 /* Initialize a channel's GSI transaction info */
gsi_channel_trans_init(struct gsi * gsi,u32 channel_id)704 int 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(channel->gsi, channel_id);
723 	atomic_set(&trans_info->tre_avail, 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(&trans_info->sg_pool,
763 				  sizeof(struct scatterlist),
764 				  tre_max, channel->trans_tre_max);
765 	if (ret)
766 		goto err_map_free;
767 
768 
769 	return 0;
770 
771 err_map_free:
772 	kfree(trans_info->map);
773 err_trans_free:
774 	kfree(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() */
gsi_channel_trans_exit(struct gsi_channel * channel)783 void 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(&trans_info->sg_pool);
788 	kfree(trans_info->trans);
789 	kfree(trans_info->map);
790 }
791