xref: /openbmc/linux/drivers/dma/mv_xor.c (revision f7777dcc)
1 /*
2  * offload engine driver for the Marvell XOR engine
3  * Copyright (C) 2007, 2008, Marvell International Ltd.
4  *
5  * This program is free software; you can redistribute it and/or modify it
6  * under the terms and conditions of the GNU General Public License,
7  * version 2, as published by the Free Software Foundation.
8  *
9  * This program is distributed in the hope it will be useful, but WITHOUT
10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
12  * more details.
13  *
14  * You should have received a copy of the GNU General Public License along with
15  * this program; if not, write to the Free Software Foundation, Inc.,
16  * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
17  */
18 
19 #include <linux/init.h>
20 #include <linux/module.h>
21 #include <linux/slab.h>
22 #include <linux/delay.h>
23 #include <linux/dma-mapping.h>
24 #include <linux/spinlock.h>
25 #include <linux/interrupt.h>
26 #include <linux/platform_device.h>
27 #include <linux/memory.h>
28 #include <linux/clk.h>
29 #include <linux/of.h>
30 #include <linux/of_irq.h>
31 #include <linux/irqdomain.h>
32 #include <linux/platform_data/dma-mv_xor.h>
33 
34 #include "dmaengine.h"
35 #include "mv_xor.h"
36 
37 static void mv_xor_issue_pending(struct dma_chan *chan);
38 
39 #define to_mv_xor_chan(chan)		\
40 	container_of(chan, struct mv_xor_chan, dmachan)
41 
42 #define to_mv_xor_slot(tx)		\
43 	container_of(tx, struct mv_xor_desc_slot, async_tx)
44 
45 #define mv_chan_to_devp(chan)           \
46 	((chan)->dmadev.dev)
47 
48 static void mv_desc_init(struct mv_xor_desc_slot *desc, unsigned long flags)
49 {
50 	struct mv_xor_desc *hw_desc = desc->hw_desc;
51 
52 	hw_desc->status = (1 << 31);
53 	hw_desc->phy_next_desc = 0;
54 	hw_desc->desc_command = (1 << 31);
55 }
56 
57 static u32 mv_desc_get_dest_addr(struct mv_xor_desc_slot *desc)
58 {
59 	struct mv_xor_desc *hw_desc = desc->hw_desc;
60 	return hw_desc->phy_dest_addr;
61 }
62 
63 static u32 mv_desc_get_src_addr(struct mv_xor_desc_slot *desc,
64 				int src_idx)
65 {
66 	struct mv_xor_desc *hw_desc = desc->hw_desc;
67 	return hw_desc->phy_src_addr[mv_phy_src_idx(src_idx)];
68 }
69 
70 
71 static void mv_desc_set_byte_count(struct mv_xor_desc_slot *desc,
72 				   u32 byte_count)
73 {
74 	struct mv_xor_desc *hw_desc = desc->hw_desc;
75 	hw_desc->byte_count = byte_count;
76 }
77 
78 static void mv_desc_set_next_desc(struct mv_xor_desc_slot *desc,
79 				  u32 next_desc_addr)
80 {
81 	struct mv_xor_desc *hw_desc = desc->hw_desc;
82 	BUG_ON(hw_desc->phy_next_desc);
83 	hw_desc->phy_next_desc = next_desc_addr;
84 }
85 
86 static void mv_desc_clear_next_desc(struct mv_xor_desc_slot *desc)
87 {
88 	struct mv_xor_desc *hw_desc = desc->hw_desc;
89 	hw_desc->phy_next_desc = 0;
90 }
91 
92 static void mv_desc_set_dest_addr(struct mv_xor_desc_slot *desc,
93 				  dma_addr_t addr)
94 {
95 	struct mv_xor_desc *hw_desc = desc->hw_desc;
96 	hw_desc->phy_dest_addr = addr;
97 }
98 
99 static int mv_chan_memset_slot_count(size_t len)
100 {
101 	return 1;
102 }
103 
104 #define mv_chan_memcpy_slot_count(c) mv_chan_memset_slot_count(c)
105 
106 static void mv_desc_set_src_addr(struct mv_xor_desc_slot *desc,
107 				 int index, dma_addr_t addr)
108 {
109 	struct mv_xor_desc *hw_desc = desc->hw_desc;
110 	hw_desc->phy_src_addr[mv_phy_src_idx(index)] = addr;
111 	if (desc->type == DMA_XOR)
112 		hw_desc->desc_command |= (1 << index);
113 }
114 
115 static u32 mv_chan_get_current_desc(struct mv_xor_chan *chan)
116 {
117 	return readl_relaxed(XOR_CURR_DESC(chan));
118 }
119 
120 static void mv_chan_set_next_descriptor(struct mv_xor_chan *chan,
121 					u32 next_desc_addr)
122 {
123 	writel_relaxed(next_desc_addr, XOR_NEXT_DESC(chan));
124 }
125 
126 static void mv_chan_unmask_interrupts(struct mv_xor_chan *chan)
127 {
128 	u32 val = readl_relaxed(XOR_INTR_MASK(chan));
129 	val |= XOR_INTR_MASK_VALUE << (chan->idx * 16);
130 	writel_relaxed(val, XOR_INTR_MASK(chan));
131 }
132 
133 static u32 mv_chan_get_intr_cause(struct mv_xor_chan *chan)
134 {
135 	u32 intr_cause = readl_relaxed(XOR_INTR_CAUSE(chan));
136 	intr_cause = (intr_cause >> (chan->idx * 16)) & 0xFFFF;
137 	return intr_cause;
138 }
139 
140 static int mv_is_err_intr(u32 intr_cause)
141 {
142 	if (intr_cause & ((1<<4)|(1<<5)|(1<<6)|(1<<7)|(1<<8)|(1<<9)))
143 		return 1;
144 
145 	return 0;
146 }
147 
148 static void mv_xor_device_clear_eoc_cause(struct mv_xor_chan *chan)
149 {
150 	u32 val = ~(1 << (chan->idx * 16));
151 	dev_dbg(mv_chan_to_devp(chan), "%s, val 0x%08x\n", __func__, val);
152 	writel_relaxed(val, XOR_INTR_CAUSE(chan));
153 }
154 
155 static void mv_xor_device_clear_err_status(struct mv_xor_chan *chan)
156 {
157 	u32 val = 0xFFFF0000 >> (chan->idx * 16);
158 	writel_relaxed(val, XOR_INTR_CAUSE(chan));
159 }
160 
161 static int mv_can_chain(struct mv_xor_desc_slot *desc)
162 {
163 	struct mv_xor_desc_slot *chain_old_tail = list_entry(
164 		desc->chain_node.prev, struct mv_xor_desc_slot, chain_node);
165 
166 	if (chain_old_tail->type != desc->type)
167 		return 0;
168 
169 	return 1;
170 }
171 
172 static void mv_set_mode(struct mv_xor_chan *chan,
173 			       enum dma_transaction_type type)
174 {
175 	u32 op_mode;
176 	u32 config = readl_relaxed(XOR_CONFIG(chan));
177 
178 	switch (type) {
179 	case DMA_XOR:
180 		op_mode = XOR_OPERATION_MODE_XOR;
181 		break;
182 	case DMA_MEMCPY:
183 		op_mode = XOR_OPERATION_MODE_MEMCPY;
184 		break;
185 	default:
186 		dev_err(mv_chan_to_devp(chan),
187 			"error: unsupported operation %d\n",
188 			type);
189 		BUG();
190 		return;
191 	}
192 
193 	config &= ~0x7;
194 	config |= op_mode;
195 
196 #if defined(__BIG_ENDIAN)
197 	config |= XOR_DESCRIPTOR_SWAP;
198 #else
199 	config &= ~XOR_DESCRIPTOR_SWAP;
200 #endif
201 
202 	writel_relaxed(config, XOR_CONFIG(chan));
203 	chan->current_type = type;
204 }
205 
206 static void mv_chan_activate(struct mv_xor_chan *chan)
207 {
208 	u32 activation;
209 
210 	dev_dbg(mv_chan_to_devp(chan), " activate chan.\n");
211 	activation = readl_relaxed(XOR_ACTIVATION(chan));
212 	activation |= 0x1;
213 	writel_relaxed(activation, XOR_ACTIVATION(chan));
214 }
215 
216 static char mv_chan_is_busy(struct mv_xor_chan *chan)
217 {
218 	u32 state = readl_relaxed(XOR_ACTIVATION(chan));
219 
220 	state = (state >> 4) & 0x3;
221 
222 	return (state == 1) ? 1 : 0;
223 }
224 
225 static int mv_chan_xor_slot_count(size_t len, int src_cnt)
226 {
227 	return 1;
228 }
229 
230 /**
231  * mv_xor_free_slots - flags descriptor slots for reuse
232  * @slot: Slot to free
233  * Caller must hold &mv_chan->lock while calling this function
234  */
235 static void mv_xor_free_slots(struct mv_xor_chan *mv_chan,
236 			      struct mv_xor_desc_slot *slot)
237 {
238 	dev_dbg(mv_chan_to_devp(mv_chan), "%s %d slot %p\n",
239 		__func__, __LINE__, slot);
240 
241 	slot->slots_per_op = 0;
242 
243 }
244 
245 /*
246  * mv_xor_start_new_chain - program the engine to operate on new chain headed by
247  * sw_desc
248  * Caller must hold &mv_chan->lock while calling this function
249  */
250 static void mv_xor_start_new_chain(struct mv_xor_chan *mv_chan,
251 				   struct mv_xor_desc_slot *sw_desc)
252 {
253 	dev_dbg(mv_chan_to_devp(mv_chan), "%s %d: sw_desc %p\n",
254 		__func__, __LINE__, sw_desc);
255 	if (sw_desc->type != mv_chan->current_type)
256 		mv_set_mode(mv_chan, sw_desc->type);
257 
258 	/* set the hardware chain */
259 	mv_chan_set_next_descriptor(mv_chan, sw_desc->async_tx.phys);
260 
261 	mv_chan->pending += sw_desc->slot_cnt;
262 	mv_xor_issue_pending(&mv_chan->dmachan);
263 }
264 
265 static dma_cookie_t
266 mv_xor_run_tx_complete_actions(struct mv_xor_desc_slot *desc,
267 	struct mv_xor_chan *mv_chan, dma_cookie_t cookie)
268 {
269 	BUG_ON(desc->async_tx.cookie < 0);
270 
271 	if (desc->async_tx.cookie > 0) {
272 		cookie = desc->async_tx.cookie;
273 
274 		/* call the callback (must not sleep or submit new
275 		 * operations to this channel)
276 		 */
277 		if (desc->async_tx.callback)
278 			desc->async_tx.callback(
279 				desc->async_tx.callback_param);
280 
281 		/* unmap dma addresses
282 		 * (unmap_single vs unmap_page?)
283 		 */
284 		if (desc->group_head && desc->unmap_len) {
285 			struct mv_xor_desc_slot *unmap = desc->group_head;
286 			struct device *dev = mv_chan_to_devp(mv_chan);
287 			u32 len = unmap->unmap_len;
288 			enum dma_ctrl_flags flags = desc->async_tx.flags;
289 			u32 src_cnt;
290 			dma_addr_t addr;
291 			dma_addr_t dest;
292 
293 			src_cnt = unmap->unmap_src_cnt;
294 			dest = mv_desc_get_dest_addr(unmap);
295 			if (!(flags & DMA_COMPL_SKIP_DEST_UNMAP)) {
296 				enum dma_data_direction dir;
297 
298 				if (src_cnt > 1) /* is xor ? */
299 					dir = DMA_BIDIRECTIONAL;
300 				else
301 					dir = DMA_FROM_DEVICE;
302 				dma_unmap_page(dev, dest, len, dir);
303 			}
304 
305 			if (!(flags & DMA_COMPL_SKIP_SRC_UNMAP)) {
306 				while (src_cnt--) {
307 					addr = mv_desc_get_src_addr(unmap,
308 								    src_cnt);
309 					if (addr == dest)
310 						continue;
311 					dma_unmap_page(dev, addr, len,
312 						       DMA_TO_DEVICE);
313 				}
314 			}
315 			desc->group_head = NULL;
316 		}
317 	}
318 
319 	/* run dependent operations */
320 	dma_run_dependencies(&desc->async_tx);
321 
322 	return cookie;
323 }
324 
325 static int
326 mv_xor_clean_completed_slots(struct mv_xor_chan *mv_chan)
327 {
328 	struct mv_xor_desc_slot *iter, *_iter;
329 
330 	dev_dbg(mv_chan_to_devp(mv_chan), "%s %d\n", __func__, __LINE__);
331 	list_for_each_entry_safe(iter, _iter, &mv_chan->completed_slots,
332 				 completed_node) {
333 
334 		if (async_tx_test_ack(&iter->async_tx)) {
335 			list_del(&iter->completed_node);
336 			mv_xor_free_slots(mv_chan, iter);
337 		}
338 	}
339 	return 0;
340 }
341 
342 static int
343 mv_xor_clean_slot(struct mv_xor_desc_slot *desc,
344 	struct mv_xor_chan *mv_chan)
345 {
346 	dev_dbg(mv_chan_to_devp(mv_chan), "%s %d: desc %p flags %d\n",
347 		__func__, __LINE__, desc, desc->async_tx.flags);
348 	list_del(&desc->chain_node);
349 	/* the client is allowed to attach dependent operations
350 	 * until 'ack' is set
351 	 */
352 	if (!async_tx_test_ack(&desc->async_tx)) {
353 		/* move this slot to the completed_slots */
354 		list_add_tail(&desc->completed_node, &mv_chan->completed_slots);
355 		return 0;
356 	}
357 
358 	mv_xor_free_slots(mv_chan, desc);
359 	return 0;
360 }
361 
362 static void __mv_xor_slot_cleanup(struct mv_xor_chan *mv_chan)
363 {
364 	struct mv_xor_desc_slot *iter, *_iter;
365 	dma_cookie_t cookie = 0;
366 	int busy = mv_chan_is_busy(mv_chan);
367 	u32 current_desc = mv_chan_get_current_desc(mv_chan);
368 	int seen_current = 0;
369 
370 	dev_dbg(mv_chan_to_devp(mv_chan), "%s %d\n", __func__, __LINE__);
371 	dev_dbg(mv_chan_to_devp(mv_chan), "current_desc %x\n", current_desc);
372 	mv_xor_clean_completed_slots(mv_chan);
373 
374 	/* free completed slots from the chain starting with
375 	 * the oldest descriptor
376 	 */
377 
378 	list_for_each_entry_safe(iter, _iter, &mv_chan->chain,
379 					chain_node) {
380 		prefetch(_iter);
381 		prefetch(&_iter->async_tx);
382 
383 		/* do not advance past the current descriptor loaded into the
384 		 * hardware channel, subsequent descriptors are either in
385 		 * process or have not been submitted
386 		 */
387 		if (seen_current)
388 			break;
389 
390 		/* stop the search if we reach the current descriptor and the
391 		 * channel is busy
392 		 */
393 		if (iter->async_tx.phys == current_desc) {
394 			seen_current = 1;
395 			if (busy)
396 				break;
397 		}
398 
399 		cookie = mv_xor_run_tx_complete_actions(iter, mv_chan, cookie);
400 
401 		if (mv_xor_clean_slot(iter, mv_chan))
402 			break;
403 	}
404 
405 	if ((busy == 0) && !list_empty(&mv_chan->chain)) {
406 		struct mv_xor_desc_slot *chain_head;
407 		chain_head = list_entry(mv_chan->chain.next,
408 					struct mv_xor_desc_slot,
409 					chain_node);
410 
411 		mv_xor_start_new_chain(mv_chan, chain_head);
412 	}
413 
414 	if (cookie > 0)
415 		mv_chan->dmachan.completed_cookie = cookie;
416 }
417 
418 static void
419 mv_xor_slot_cleanup(struct mv_xor_chan *mv_chan)
420 {
421 	spin_lock_bh(&mv_chan->lock);
422 	__mv_xor_slot_cleanup(mv_chan);
423 	spin_unlock_bh(&mv_chan->lock);
424 }
425 
426 static void mv_xor_tasklet(unsigned long data)
427 {
428 	struct mv_xor_chan *chan = (struct mv_xor_chan *) data;
429 	mv_xor_slot_cleanup(chan);
430 }
431 
432 static struct mv_xor_desc_slot *
433 mv_xor_alloc_slots(struct mv_xor_chan *mv_chan, int num_slots,
434 		    int slots_per_op)
435 {
436 	struct mv_xor_desc_slot *iter, *_iter, *alloc_start = NULL;
437 	LIST_HEAD(chain);
438 	int slots_found, retry = 0;
439 
440 	/* start search from the last allocated descrtiptor
441 	 * if a contiguous allocation can not be found start searching
442 	 * from the beginning of the list
443 	 */
444 retry:
445 	slots_found = 0;
446 	if (retry == 0)
447 		iter = mv_chan->last_used;
448 	else
449 		iter = list_entry(&mv_chan->all_slots,
450 			struct mv_xor_desc_slot,
451 			slot_node);
452 
453 	list_for_each_entry_safe_continue(
454 		iter, _iter, &mv_chan->all_slots, slot_node) {
455 		prefetch(_iter);
456 		prefetch(&_iter->async_tx);
457 		if (iter->slots_per_op) {
458 			/* give up after finding the first busy slot
459 			 * on the second pass through the list
460 			 */
461 			if (retry)
462 				break;
463 
464 			slots_found = 0;
465 			continue;
466 		}
467 
468 		/* start the allocation if the slot is correctly aligned */
469 		if (!slots_found++)
470 			alloc_start = iter;
471 
472 		if (slots_found == num_slots) {
473 			struct mv_xor_desc_slot *alloc_tail = NULL;
474 			struct mv_xor_desc_slot *last_used = NULL;
475 			iter = alloc_start;
476 			while (num_slots) {
477 				int i;
478 
479 				/* pre-ack all but the last descriptor */
480 				async_tx_ack(&iter->async_tx);
481 
482 				list_add_tail(&iter->chain_node, &chain);
483 				alloc_tail = iter;
484 				iter->async_tx.cookie = 0;
485 				iter->slot_cnt = num_slots;
486 				iter->xor_check_result = NULL;
487 				for (i = 0; i < slots_per_op; i++) {
488 					iter->slots_per_op = slots_per_op - i;
489 					last_used = iter;
490 					iter = list_entry(iter->slot_node.next,
491 						struct mv_xor_desc_slot,
492 						slot_node);
493 				}
494 				num_slots -= slots_per_op;
495 			}
496 			alloc_tail->group_head = alloc_start;
497 			alloc_tail->async_tx.cookie = -EBUSY;
498 			list_splice(&chain, &alloc_tail->tx_list);
499 			mv_chan->last_used = last_used;
500 			mv_desc_clear_next_desc(alloc_start);
501 			mv_desc_clear_next_desc(alloc_tail);
502 			return alloc_tail;
503 		}
504 	}
505 	if (!retry++)
506 		goto retry;
507 
508 	/* try to free some slots if the allocation fails */
509 	tasklet_schedule(&mv_chan->irq_tasklet);
510 
511 	return NULL;
512 }
513 
514 /************************ DMA engine API functions ****************************/
515 static dma_cookie_t
516 mv_xor_tx_submit(struct dma_async_tx_descriptor *tx)
517 {
518 	struct mv_xor_desc_slot *sw_desc = to_mv_xor_slot(tx);
519 	struct mv_xor_chan *mv_chan = to_mv_xor_chan(tx->chan);
520 	struct mv_xor_desc_slot *grp_start, *old_chain_tail;
521 	dma_cookie_t cookie;
522 	int new_hw_chain = 1;
523 
524 	dev_dbg(mv_chan_to_devp(mv_chan),
525 		"%s sw_desc %p: async_tx %p\n",
526 		__func__, sw_desc, &sw_desc->async_tx);
527 
528 	grp_start = sw_desc->group_head;
529 
530 	spin_lock_bh(&mv_chan->lock);
531 	cookie = dma_cookie_assign(tx);
532 
533 	if (list_empty(&mv_chan->chain))
534 		list_splice_init(&sw_desc->tx_list, &mv_chan->chain);
535 	else {
536 		new_hw_chain = 0;
537 
538 		old_chain_tail = list_entry(mv_chan->chain.prev,
539 					    struct mv_xor_desc_slot,
540 					    chain_node);
541 		list_splice_init(&grp_start->tx_list,
542 				 &old_chain_tail->chain_node);
543 
544 		if (!mv_can_chain(grp_start))
545 			goto submit_done;
546 
547 		dev_dbg(mv_chan_to_devp(mv_chan), "Append to last desc %x\n",
548 			old_chain_tail->async_tx.phys);
549 
550 		/* fix up the hardware chain */
551 		mv_desc_set_next_desc(old_chain_tail, grp_start->async_tx.phys);
552 
553 		/* if the channel is not busy */
554 		if (!mv_chan_is_busy(mv_chan)) {
555 			u32 current_desc = mv_chan_get_current_desc(mv_chan);
556 			/*
557 			 * and the curren desc is the end of the chain before
558 			 * the append, then we need to start the channel
559 			 */
560 			if (current_desc == old_chain_tail->async_tx.phys)
561 				new_hw_chain = 1;
562 		}
563 	}
564 
565 	if (new_hw_chain)
566 		mv_xor_start_new_chain(mv_chan, grp_start);
567 
568 submit_done:
569 	spin_unlock_bh(&mv_chan->lock);
570 
571 	return cookie;
572 }
573 
574 /* returns the number of allocated descriptors */
575 static int mv_xor_alloc_chan_resources(struct dma_chan *chan)
576 {
577 	char *hw_desc;
578 	int idx;
579 	struct mv_xor_chan *mv_chan = to_mv_xor_chan(chan);
580 	struct mv_xor_desc_slot *slot = NULL;
581 	int num_descs_in_pool = MV_XOR_POOL_SIZE/MV_XOR_SLOT_SIZE;
582 
583 	/* Allocate descriptor slots */
584 	idx = mv_chan->slots_allocated;
585 	while (idx < num_descs_in_pool) {
586 		slot = kzalloc(sizeof(*slot), GFP_KERNEL);
587 		if (!slot) {
588 			printk(KERN_INFO "MV XOR Channel only initialized"
589 				" %d descriptor slots", idx);
590 			break;
591 		}
592 		hw_desc = (char *) mv_chan->dma_desc_pool_virt;
593 		slot->hw_desc = (void *) &hw_desc[idx * MV_XOR_SLOT_SIZE];
594 
595 		dma_async_tx_descriptor_init(&slot->async_tx, chan);
596 		slot->async_tx.tx_submit = mv_xor_tx_submit;
597 		INIT_LIST_HEAD(&slot->chain_node);
598 		INIT_LIST_HEAD(&slot->slot_node);
599 		INIT_LIST_HEAD(&slot->tx_list);
600 		hw_desc = (char *) mv_chan->dma_desc_pool;
601 		slot->async_tx.phys =
602 			(dma_addr_t) &hw_desc[idx * MV_XOR_SLOT_SIZE];
603 		slot->idx = idx++;
604 
605 		spin_lock_bh(&mv_chan->lock);
606 		mv_chan->slots_allocated = idx;
607 		list_add_tail(&slot->slot_node, &mv_chan->all_slots);
608 		spin_unlock_bh(&mv_chan->lock);
609 	}
610 
611 	if (mv_chan->slots_allocated && !mv_chan->last_used)
612 		mv_chan->last_used = list_entry(mv_chan->all_slots.next,
613 					struct mv_xor_desc_slot,
614 					slot_node);
615 
616 	dev_dbg(mv_chan_to_devp(mv_chan),
617 		"allocated %d descriptor slots last_used: %p\n",
618 		mv_chan->slots_allocated, mv_chan->last_used);
619 
620 	return mv_chan->slots_allocated ? : -ENOMEM;
621 }
622 
623 static struct dma_async_tx_descriptor *
624 mv_xor_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
625 		size_t len, unsigned long flags)
626 {
627 	struct mv_xor_chan *mv_chan = to_mv_xor_chan(chan);
628 	struct mv_xor_desc_slot *sw_desc, *grp_start;
629 	int slot_cnt;
630 
631 	dev_dbg(mv_chan_to_devp(mv_chan),
632 		"%s dest: %x src %x len: %u flags: %ld\n",
633 		__func__, dest, src, len, flags);
634 	if (unlikely(len < MV_XOR_MIN_BYTE_COUNT))
635 		return NULL;
636 
637 	BUG_ON(len > MV_XOR_MAX_BYTE_COUNT);
638 
639 	spin_lock_bh(&mv_chan->lock);
640 	slot_cnt = mv_chan_memcpy_slot_count(len);
641 	sw_desc = mv_xor_alloc_slots(mv_chan, slot_cnt, 1);
642 	if (sw_desc) {
643 		sw_desc->type = DMA_MEMCPY;
644 		sw_desc->async_tx.flags = flags;
645 		grp_start = sw_desc->group_head;
646 		mv_desc_init(grp_start, flags);
647 		mv_desc_set_byte_count(grp_start, len);
648 		mv_desc_set_dest_addr(sw_desc->group_head, dest);
649 		mv_desc_set_src_addr(grp_start, 0, src);
650 		sw_desc->unmap_src_cnt = 1;
651 		sw_desc->unmap_len = len;
652 	}
653 	spin_unlock_bh(&mv_chan->lock);
654 
655 	dev_dbg(mv_chan_to_devp(mv_chan),
656 		"%s sw_desc %p async_tx %p\n",
657 		__func__, sw_desc, sw_desc ? &sw_desc->async_tx : NULL);
658 
659 	return sw_desc ? &sw_desc->async_tx : NULL;
660 }
661 
662 static struct dma_async_tx_descriptor *
663 mv_xor_prep_dma_xor(struct dma_chan *chan, dma_addr_t dest, dma_addr_t *src,
664 		    unsigned int src_cnt, size_t len, unsigned long flags)
665 {
666 	struct mv_xor_chan *mv_chan = to_mv_xor_chan(chan);
667 	struct mv_xor_desc_slot *sw_desc, *grp_start;
668 	int slot_cnt;
669 
670 	if (unlikely(len < MV_XOR_MIN_BYTE_COUNT))
671 		return NULL;
672 
673 	BUG_ON(len > MV_XOR_MAX_BYTE_COUNT);
674 
675 	dev_dbg(mv_chan_to_devp(mv_chan),
676 		"%s src_cnt: %d len: dest %x %u flags: %ld\n",
677 		__func__, src_cnt, len, dest, flags);
678 
679 	spin_lock_bh(&mv_chan->lock);
680 	slot_cnt = mv_chan_xor_slot_count(len, src_cnt);
681 	sw_desc = mv_xor_alloc_slots(mv_chan, slot_cnt, 1);
682 	if (sw_desc) {
683 		sw_desc->type = DMA_XOR;
684 		sw_desc->async_tx.flags = flags;
685 		grp_start = sw_desc->group_head;
686 		mv_desc_init(grp_start, flags);
687 		/* the byte count field is the same as in memcpy desc*/
688 		mv_desc_set_byte_count(grp_start, len);
689 		mv_desc_set_dest_addr(sw_desc->group_head, dest);
690 		sw_desc->unmap_src_cnt = src_cnt;
691 		sw_desc->unmap_len = len;
692 		while (src_cnt--)
693 			mv_desc_set_src_addr(grp_start, src_cnt, src[src_cnt]);
694 	}
695 	spin_unlock_bh(&mv_chan->lock);
696 	dev_dbg(mv_chan_to_devp(mv_chan),
697 		"%s sw_desc %p async_tx %p \n",
698 		__func__, sw_desc, &sw_desc->async_tx);
699 	return sw_desc ? &sw_desc->async_tx : NULL;
700 }
701 
702 static void mv_xor_free_chan_resources(struct dma_chan *chan)
703 {
704 	struct mv_xor_chan *mv_chan = to_mv_xor_chan(chan);
705 	struct mv_xor_desc_slot *iter, *_iter;
706 	int in_use_descs = 0;
707 
708 	mv_xor_slot_cleanup(mv_chan);
709 
710 	spin_lock_bh(&mv_chan->lock);
711 	list_for_each_entry_safe(iter, _iter, &mv_chan->chain,
712 					chain_node) {
713 		in_use_descs++;
714 		list_del(&iter->chain_node);
715 	}
716 	list_for_each_entry_safe(iter, _iter, &mv_chan->completed_slots,
717 				 completed_node) {
718 		in_use_descs++;
719 		list_del(&iter->completed_node);
720 	}
721 	list_for_each_entry_safe_reverse(
722 		iter, _iter, &mv_chan->all_slots, slot_node) {
723 		list_del(&iter->slot_node);
724 		kfree(iter);
725 		mv_chan->slots_allocated--;
726 	}
727 	mv_chan->last_used = NULL;
728 
729 	dev_dbg(mv_chan_to_devp(mv_chan), "%s slots_allocated %d\n",
730 		__func__, mv_chan->slots_allocated);
731 	spin_unlock_bh(&mv_chan->lock);
732 
733 	if (in_use_descs)
734 		dev_err(mv_chan_to_devp(mv_chan),
735 			"freeing %d in use descriptors!\n", in_use_descs);
736 }
737 
738 /**
739  * mv_xor_status - poll the status of an XOR transaction
740  * @chan: XOR channel handle
741  * @cookie: XOR transaction identifier
742  * @txstate: XOR transactions state holder (or NULL)
743  */
744 static enum dma_status mv_xor_status(struct dma_chan *chan,
745 					  dma_cookie_t cookie,
746 					  struct dma_tx_state *txstate)
747 {
748 	struct mv_xor_chan *mv_chan = to_mv_xor_chan(chan);
749 	enum dma_status ret;
750 
751 	ret = dma_cookie_status(chan, cookie, txstate);
752 	if (ret == DMA_SUCCESS) {
753 		mv_xor_clean_completed_slots(mv_chan);
754 		return ret;
755 	}
756 	mv_xor_slot_cleanup(mv_chan);
757 
758 	return dma_cookie_status(chan, cookie, txstate);
759 }
760 
761 static void mv_dump_xor_regs(struct mv_xor_chan *chan)
762 {
763 	u32 val;
764 
765 	val = readl_relaxed(XOR_CONFIG(chan));
766 	dev_err(mv_chan_to_devp(chan), "config       0x%08x\n", val);
767 
768 	val = readl_relaxed(XOR_ACTIVATION(chan));
769 	dev_err(mv_chan_to_devp(chan), "activation   0x%08x\n", val);
770 
771 	val = readl_relaxed(XOR_INTR_CAUSE(chan));
772 	dev_err(mv_chan_to_devp(chan), "intr cause   0x%08x\n", val);
773 
774 	val = readl_relaxed(XOR_INTR_MASK(chan));
775 	dev_err(mv_chan_to_devp(chan), "intr mask    0x%08x\n", val);
776 
777 	val = readl_relaxed(XOR_ERROR_CAUSE(chan));
778 	dev_err(mv_chan_to_devp(chan), "error cause  0x%08x\n", val);
779 
780 	val = readl_relaxed(XOR_ERROR_ADDR(chan));
781 	dev_err(mv_chan_to_devp(chan), "error addr   0x%08x\n", val);
782 }
783 
784 static void mv_xor_err_interrupt_handler(struct mv_xor_chan *chan,
785 					 u32 intr_cause)
786 {
787 	if (intr_cause & (1 << 4)) {
788 	     dev_dbg(mv_chan_to_devp(chan),
789 		     "ignore this error\n");
790 	     return;
791 	}
792 
793 	dev_err(mv_chan_to_devp(chan),
794 		"error on chan %d. intr cause 0x%08x\n",
795 		chan->idx, intr_cause);
796 
797 	mv_dump_xor_regs(chan);
798 	BUG();
799 }
800 
801 static irqreturn_t mv_xor_interrupt_handler(int irq, void *data)
802 {
803 	struct mv_xor_chan *chan = data;
804 	u32 intr_cause = mv_chan_get_intr_cause(chan);
805 
806 	dev_dbg(mv_chan_to_devp(chan), "intr cause %x\n", intr_cause);
807 
808 	if (mv_is_err_intr(intr_cause))
809 		mv_xor_err_interrupt_handler(chan, intr_cause);
810 
811 	tasklet_schedule(&chan->irq_tasklet);
812 
813 	mv_xor_device_clear_eoc_cause(chan);
814 
815 	return IRQ_HANDLED;
816 }
817 
818 static void mv_xor_issue_pending(struct dma_chan *chan)
819 {
820 	struct mv_xor_chan *mv_chan = to_mv_xor_chan(chan);
821 
822 	if (mv_chan->pending >= MV_XOR_THRESHOLD) {
823 		mv_chan->pending = 0;
824 		mv_chan_activate(mv_chan);
825 	}
826 }
827 
828 /*
829  * Perform a transaction to verify the HW works.
830  */
831 #define MV_XOR_TEST_SIZE 2000
832 
833 static int mv_xor_memcpy_self_test(struct mv_xor_chan *mv_chan)
834 {
835 	int i;
836 	void *src, *dest;
837 	dma_addr_t src_dma, dest_dma;
838 	struct dma_chan *dma_chan;
839 	dma_cookie_t cookie;
840 	struct dma_async_tx_descriptor *tx;
841 	int err = 0;
842 
843 	src = kmalloc(sizeof(u8) * MV_XOR_TEST_SIZE, GFP_KERNEL);
844 	if (!src)
845 		return -ENOMEM;
846 
847 	dest = kzalloc(sizeof(u8) * MV_XOR_TEST_SIZE, GFP_KERNEL);
848 	if (!dest) {
849 		kfree(src);
850 		return -ENOMEM;
851 	}
852 
853 	/* Fill in src buffer */
854 	for (i = 0; i < MV_XOR_TEST_SIZE; i++)
855 		((u8 *) src)[i] = (u8)i;
856 
857 	dma_chan = &mv_chan->dmachan;
858 	if (mv_xor_alloc_chan_resources(dma_chan) < 1) {
859 		err = -ENODEV;
860 		goto out;
861 	}
862 
863 	dest_dma = dma_map_single(dma_chan->device->dev, dest,
864 				  MV_XOR_TEST_SIZE, DMA_FROM_DEVICE);
865 
866 	src_dma = dma_map_single(dma_chan->device->dev, src,
867 				 MV_XOR_TEST_SIZE, DMA_TO_DEVICE);
868 
869 	tx = mv_xor_prep_dma_memcpy(dma_chan, dest_dma, src_dma,
870 				    MV_XOR_TEST_SIZE, 0);
871 	cookie = mv_xor_tx_submit(tx);
872 	mv_xor_issue_pending(dma_chan);
873 	async_tx_ack(tx);
874 	msleep(1);
875 
876 	if (mv_xor_status(dma_chan, cookie, NULL) !=
877 	    DMA_SUCCESS) {
878 		dev_err(dma_chan->device->dev,
879 			"Self-test copy timed out, disabling\n");
880 		err = -ENODEV;
881 		goto free_resources;
882 	}
883 
884 	dma_sync_single_for_cpu(dma_chan->device->dev, dest_dma,
885 				MV_XOR_TEST_SIZE, DMA_FROM_DEVICE);
886 	if (memcmp(src, dest, MV_XOR_TEST_SIZE)) {
887 		dev_err(dma_chan->device->dev,
888 			"Self-test copy failed compare, disabling\n");
889 		err = -ENODEV;
890 		goto free_resources;
891 	}
892 
893 free_resources:
894 	mv_xor_free_chan_resources(dma_chan);
895 out:
896 	kfree(src);
897 	kfree(dest);
898 	return err;
899 }
900 
901 #define MV_XOR_NUM_SRC_TEST 4 /* must be <= 15 */
902 static int
903 mv_xor_xor_self_test(struct mv_xor_chan *mv_chan)
904 {
905 	int i, src_idx;
906 	struct page *dest;
907 	struct page *xor_srcs[MV_XOR_NUM_SRC_TEST];
908 	dma_addr_t dma_srcs[MV_XOR_NUM_SRC_TEST];
909 	dma_addr_t dest_dma;
910 	struct dma_async_tx_descriptor *tx;
911 	struct dma_chan *dma_chan;
912 	dma_cookie_t cookie;
913 	u8 cmp_byte = 0;
914 	u32 cmp_word;
915 	int err = 0;
916 
917 	for (src_idx = 0; src_idx < MV_XOR_NUM_SRC_TEST; src_idx++) {
918 		xor_srcs[src_idx] = alloc_page(GFP_KERNEL);
919 		if (!xor_srcs[src_idx]) {
920 			while (src_idx--)
921 				__free_page(xor_srcs[src_idx]);
922 			return -ENOMEM;
923 		}
924 	}
925 
926 	dest = alloc_page(GFP_KERNEL);
927 	if (!dest) {
928 		while (src_idx--)
929 			__free_page(xor_srcs[src_idx]);
930 		return -ENOMEM;
931 	}
932 
933 	/* Fill in src buffers */
934 	for (src_idx = 0; src_idx < MV_XOR_NUM_SRC_TEST; src_idx++) {
935 		u8 *ptr = page_address(xor_srcs[src_idx]);
936 		for (i = 0; i < PAGE_SIZE; i++)
937 			ptr[i] = (1 << src_idx);
938 	}
939 
940 	for (src_idx = 0; src_idx < MV_XOR_NUM_SRC_TEST; src_idx++)
941 		cmp_byte ^= (u8) (1 << src_idx);
942 
943 	cmp_word = (cmp_byte << 24) | (cmp_byte << 16) |
944 		(cmp_byte << 8) | cmp_byte;
945 
946 	memset(page_address(dest), 0, PAGE_SIZE);
947 
948 	dma_chan = &mv_chan->dmachan;
949 	if (mv_xor_alloc_chan_resources(dma_chan) < 1) {
950 		err = -ENODEV;
951 		goto out;
952 	}
953 
954 	/* test xor */
955 	dest_dma = dma_map_page(dma_chan->device->dev, dest, 0, PAGE_SIZE,
956 				DMA_FROM_DEVICE);
957 
958 	for (i = 0; i < MV_XOR_NUM_SRC_TEST; i++)
959 		dma_srcs[i] = dma_map_page(dma_chan->device->dev, xor_srcs[i],
960 					   0, PAGE_SIZE, DMA_TO_DEVICE);
961 
962 	tx = mv_xor_prep_dma_xor(dma_chan, dest_dma, dma_srcs,
963 				 MV_XOR_NUM_SRC_TEST, PAGE_SIZE, 0);
964 
965 	cookie = mv_xor_tx_submit(tx);
966 	mv_xor_issue_pending(dma_chan);
967 	async_tx_ack(tx);
968 	msleep(8);
969 
970 	if (mv_xor_status(dma_chan, cookie, NULL) !=
971 	    DMA_SUCCESS) {
972 		dev_err(dma_chan->device->dev,
973 			"Self-test xor timed out, disabling\n");
974 		err = -ENODEV;
975 		goto free_resources;
976 	}
977 
978 	dma_sync_single_for_cpu(dma_chan->device->dev, dest_dma,
979 				PAGE_SIZE, DMA_FROM_DEVICE);
980 	for (i = 0; i < (PAGE_SIZE / sizeof(u32)); i++) {
981 		u32 *ptr = page_address(dest);
982 		if (ptr[i] != cmp_word) {
983 			dev_err(dma_chan->device->dev,
984 				"Self-test xor failed compare, disabling. index %d, data %x, expected %x\n",
985 				i, ptr[i], cmp_word);
986 			err = -ENODEV;
987 			goto free_resources;
988 		}
989 	}
990 
991 free_resources:
992 	mv_xor_free_chan_resources(dma_chan);
993 out:
994 	src_idx = MV_XOR_NUM_SRC_TEST;
995 	while (src_idx--)
996 		__free_page(xor_srcs[src_idx]);
997 	__free_page(dest);
998 	return err;
999 }
1000 
1001 /* This driver does not implement any of the optional DMA operations. */
1002 static int
1003 mv_xor_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
1004 	       unsigned long arg)
1005 {
1006 	return -ENOSYS;
1007 }
1008 
1009 static int mv_xor_channel_remove(struct mv_xor_chan *mv_chan)
1010 {
1011 	struct dma_chan *chan, *_chan;
1012 	struct device *dev = mv_chan->dmadev.dev;
1013 
1014 	dma_async_device_unregister(&mv_chan->dmadev);
1015 
1016 	dma_free_coherent(dev, MV_XOR_POOL_SIZE,
1017 			  mv_chan->dma_desc_pool_virt, mv_chan->dma_desc_pool);
1018 
1019 	list_for_each_entry_safe(chan, _chan, &mv_chan->dmadev.channels,
1020 				 device_node) {
1021 		list_del(&chan->device_node);
1022 	}
1023 
1024 	free_irq(mv_chan->irq, mv_chan);
1025 
1026 	return 0;
1027 }
1028 
1029 static struct mv_xor_chan *
1030 mv_xor_channel_add(struct mv_xor_device *xordev,
1031 		   struct platform_device *pdev,
1032 		   int idx, dma_cap_mask_t cap_mask, int irq)
1033 {
1034 	int ret = 0;
1035 	struct mv_xor_chan *mv_chan;
1036 	struct dma_device *dma_dev;
1037 
1038 	mv_chan = devm_kzalloc(&pdev->dev, sizeof(*mv_chan), GFP_KERNEL);
1039 	if (!mv_chan)
1040 		return ERR_PTR(-ENOMEM);
1041 
1042 	mv_chan->idx = idx;
1043 	mv_chan->irq = irq;
1044 
1045 	dma_dev = &mv_chan->dmadev;
1046 
1047 	/* allocate coherent memory for hardware descriptors
1048 	 * note: writecombine gives slightly better performance, but
1049 	 * requires that we explicitly flush the writes
1050 	 */
1051 	mv_chan->dma_desc_pool_virt =
1052 	  dma_alloc_writecombine(&pdev->dev, MV_XOR_POOL_SIZE,
1053 				 &mv_chan->dma_desc_pool, GFP_KERNEL);
1054 	if (!mv_chan->dma_desc_pool_virt)
1055 		return ERR_PTR(-ENOMEM);
1056 
1057 	/* discover transaction capabilites from the platform data */
1058 	dma_dev->cap_mask = cap_mask;
1059 
1060 	INIT_LIST_HEAD(&dma_dev->channels);
1061 
1062 	/* set base routines */
1063 	dma_dev->device_alloc_chan_resources = mv_xor_alloc_chan_resources;
1064 	dma_dev->device_free_chan_resources = mv_xor_free_chan_resources;
1065 	dma_dev->device_tx_status = mv_xor_status;
1066 	dma_dev->device_issue_pending = mv_xor_issue_pending;
1067 	dma_dev->device_control = mv_xor_control;
1068 	dma_dev->dev = &pdev->dev;
1069 
1070 	/* set prep routines based on capability */
1071 	if (dma_has_cap(DMA_MEMCPY, dma_dev->cap_mask))
1072 		dma_dev->device_prep_dma_memcpy = mv_xor_prep_dma_memcpy;
1073 	if (dma_has_cap(DMA_XOR, dma_dev->cap_mask)) {
1074 		dma_dev->max_xor = 8;
1075 		dma_dev->device_prep_dma_xor = mv_xor_prep_dma_xor;
1076 	}
1077 
1078 	mv_chan->mmr_base = xordev->xor_base;
1079 	if (!mv_chan->mmr_base) {
1080 		ret = -ENOMEM;
1081 		goto err_free_dma;
1082 	}
1083 	tasklet_init(&mv_chan->irq_tasklet, mv_xor_tasklet, (unsigned long)
1084 		     mv_chan);
1085 
1086 	/* clear errors before enabling interrupts */
1087 	mv_xor_device_clear_err_status(mv_chan);
1088 
1089 	ret = request_irq(mv_chan->irq, mv_xor_interrupt_handler,
1090 			  0, dev_name(&pdev->dev), mv_chan);
1091 	if (ret)
1092 		goto err_free_dma;
1093 
1094 	mv_chan_unmask_interrupts(mv_chan);
1095 
1096 	mv_set_mode(mv_chan, DMA_MEMCPY);
1097 
1098 	spin_lock_init(&mv_chan->lock);
1099 	INIT_LIST_HEAD(&mv_chan->chain);
1100 	INIT_LIST_HEAD(&mv_chan->completed_slots);
1101 	INIT_LIST_HEAD(&mv_chan->all_slots);
1102 	mv_chan->dmachan.device = dma_dev;
1103 	dma_cookie_init(&mv_chan->dmachan);
1104 
1105 	list_add_tail(&mv_chan->dmachan.device_node, &dma_dev->channels);
1106 
1107 	if (dma_has_cap(DMA_MEMCPY, dma_dev->cap_mask)) {
1108 		ret = mv_xor_memcpy_self_test(mv_chan);
1109 		dev_dbg(&pdev->dev, "memcpy self test returned %d\n", ret);
1110 		if (ret)
1111 			goto err_free_irq;
1112 	}
1113 
1114 	if (dma_has_cap(DMA_XOR, dma_dev->cap_mask)) {
1115 		ret = mv_xor_xor_self_test(mv_chan);
1116 		dev_dbg(&pdev->dev, "xor self test returned %d\n", ret);
1117 		if (ret)
1118 			goto err_free_irq;
1119 	}
1120 
1121 	dev_info(&pdev->dev, "Marvell XOR: ( %s%s%s)\n",
1122 		 dma_has_cap(DMA_XOR, dma_dev->cap_mask) ? "xor " : "",
1123 		 dma_has_cap(DMA_MEMCPY, dma_dev->cap_mask) ? "cpy " : "",
1124 		 dma_has_cap(DMA_INTERRUPT, dma_dev->cap_mask) ? "intr " : "");
1125 
1126 	dma_async_device_register(dma_dev);
1127 	return mv_chan;
1128 
1129 err_free_irq:
1130 	free_irq(mv_chan->irq, mv_chan);
1131  err_free_dma:
1132 	dma_free_coherent(&pdev->dev, MV_XOR_POOL_SIZE,
1133 			  mv_chan->dma_desc_pool_virt, mv_chan->dma_desc_pool);
1134 	return ERR_PTR(ret);
1135 }
1136 
1137 static void
1138 mv_xor_conf_mbus_windows(struct mv_xor_device *xordev,
1139 			 const struct mbus_dram_target_info *dram)
1140 {
1141 	void __iomem *base = xordev->xor_base;
1142 	u32 win_enable = 0;
1143 	int i;
1144 
1145 	for (i = 0; i < 8; i++) {
1146 		writel(0, base + WINDOW_BASE(i));
1147 		writel(0, base + WINDOW_SIZE(i));
1148 		if (i < 4)
1149 			writel(0, base + WINDOW_REMAP_HIGH(i));
1150 	}
1151 
1152 	for (i = 0; i < dram->num_cs; i++) {
1153 		const struct mbus_dram_window *cs = dram->cs + i;
1154 
1155 		writel((cs->base & 0xffff0000) |
1156 		       (cs->mbus_attr << 8) |
1157 		       dram->mbus_dram_target_id, base + WINDOW_BASE(i));
1158 		writel((cs->size - 1) & 0xffff0000, base + WINDOW_SIZE(i));
1159 
1160 		win_enable |= (1 << i);
1161 		win_enable |= 3 << (16 + (2 * i));
1162 	}
1163 
1164 	writel(win_enable, base + WINDOW_BAR_ENABLE(0));
1165 	writel(win_enable, base + WINDOW_BAR_ENABLE(1));
1166 	writel(0, base + WINDOW_OVERRIDE_CTRL(0));
1167 	writel(0, base + WINDOW_OVERRIDE_CTRL(1));
1168 }
1169 
1170 static int mv_xor_probe(struct platform_device *pdev)
1171 {
1172 	const struct mbus_dram_target_info *dram;
1173 	struct mv_xor_device *xordev;
1174 	struct mv_xor_platform_data *pdata = dev_get_platdata(&pdev->dev);
1175 	struct resource *res;
1176 	int i, ret;
1177 
1178 	dev_notice(&pdev->dev, "Marvell shared XOR driver\n");
1179 
1180 	xordev = devm_kzalloc(&pdev->dev, sizeof(*xordev), GFP_KERNEL);
1181 	if (!xordev)
1182 		return -ENOMEM;
1183 
1184 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
1185 	if (!res)
1186 		return -ENODEV;
1187 
1188 	xordev->xor_base = devm_ioremap(&pdev->dev, res->start,
1189 					resource_size(res));
1190 	if (!xordev->xor_base)
1191 		return -EBUSY;
1192 
1193 	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
1194 	if (!res)
1195 		return -ENODEV;
1196 
1197 	xordev->xor_high_base = devm_ioremap(&pdev->dev, res->start,
1198 					     resource_size(res));
1199 	if (!xordev->xor_high_base)
1200 		return -EBUSY;
1201 
1202 	platform_set_drvdata(pdev, xordev);
1203 
1204 	/*
1205 	 * (Re-)program MBUS remapping windows if we are asked to.
1206 	 */
1207 	dram = mv_mbus_dram_info();
1208 	if (dram)
1209 		mv_xor_conf_mbus_windows(xordev, dram);
1210 
1211 	/* Not all platforms can gate the clock, so it is not
1212 	 * an error if the clock does not exists.
1213 	 */
1214 	xordev->clk = clk_get(&pdev->dev, NULL);
1215 	if (!IS_ERR(xordev->clk))
1216 		clk_prepare_enable(xordev->clk);
1217 
1218 	if (pdev->dev.of_node) {
1219 		struct device_node *np;
1220 		int i = 0;
1221 
1222 		for_each_child_of_node(pdev->dev.of_node, np) {
1223 			dma_cap_mask_t cap_mask;
1224 			int irq;
1225 
1226 			dma_cap_zero(cap_mask);
1227 			if (of_property_read_bool(np, "dmacap,memcpy"))
1228 				dma_cap_set(DMA_MEMCPY, cap_mask);
1229 			if (of_property_read_bool(np, "dmacap,xor"))
1230 				dma_cap_set(DMA_XOR, cap_mask);
1231 			if (of_property_read_bool(np, "dmacap,interrupt"))
1232 				dma_cap_set(DMA_INTERRUPT, cap_mask);
1233 
1234 			irq = irq_of_parse_and_map(np, 0);
1235 			if (!irq) {
1236 				ret = -ENODEV;
1237 				goto err_channel_add;
1238 			}
1239 
1240 			xordev->channels[i] =
1241 				mv_xor_channel_add(xordev, pdev, i,
1242 						   cap_mask, irq);
1243 			if (IS_ERR(xordev->channels[i])) {
1244 				ret = PTR_ERR(xordev->channels[i]);
1245 				xordev->channels[i] = NULL;
1246 				irq_dispose_mapping(irq);
1247 				goto err_channel_add;
1248 			}
1249 
1250 			i++;
1251 		}
1252 	} else if (pdata && pdata->channels) {
1253 		for (i = 0; i < MV_XOR_MAX_CHANNELS; i++) {
1254 			struct mv_xor_channel_data *cd;
1255 			int irq;
1256 
1257 			cd = &pdata->channels[i];
1258 			if (!cd) {
1259 				ret = -ENODEV;
1260 				goto err_channel_add;
1261 			}
1262 
1263 			irq = platform_get_irq(pdev, i);
1264 			if (irq < 0) {
1265 				ret = irq;
1266 				goto err_channel_add;
1267 			}
1268 
1269 			xordev->channels[i] =
1270 				mv_xor_channel_add(xordev, pdev, i,
1271 						   cd->cap_mask, irq);
1272 			if (IS_ERR(xordev->channels[i])) {
1273 				ret = PTR_ERR(xordev->channels[i]);
1274 				goto err_channel_add;
1275 			}
1276 		}
1277 	}
1278 
1279 	return 0;
1280 
1281 err_channel_add:
1282 	for (i = 0; i < MV_XOR_MAX_CHANNELS; i++)
1283 		if (xordev->channels[i]) {
1284 			mv_xor_channel_remove(xordev->channels[i]);
1285 			if (pdev->dev.of_node)
1286 				irq_dispose_mapping(xordev->channels[i]->irq);
1287 		}
1288 
1289 	if (!IS_ERR(xordev->clk)) {
1290 		clk_disable_unprepare(xordev->clk);
1291 		clk_put(xordev->clk);
1292 	}
1293 
1294 	return ret;
1295 }
1296 
1297 static int mv_xor_remove(struct platform_device *pdev)
1298 {
1299 	struct mv_xor_device *xordev = platform_get_drvdata(pdev);
1300 	int i;
1301 
1302 	for (i = 0; i < MV_XOR_MAX_CHANNELS; i++) {
1303 		if (xordev->channels[i])
1304 			mv_xor_channel_remove(xordev->channels[i]);
1305 	}
1306 
1307 	if (!IS_ERR(xordev->clk)) {
1308 		clk_disable_unprepare(xordev->clk);
1309 		clk_put(xordev->clk);
1310 	}
1311 
1312 	return 0;
1313 }
1314 
1315 #ifdef CONFIG_OF
1316 static struct of_device_id mv_xor_dt_ids[] = {
1317        { .compatible = "marvell,orion-xor", },
1318        {},
1319 };
1320 MODULE_DEVICE_TABLE(of, mv_xor_dt_ids);
1321 #endif
1322 
1323 static struct platform_driver mv_xor_driver = {
1324 	.probe		= mv_xor_probe,
1325 	.remove		= mv_xor_remove,
1326 	.driver		= {
1327 		.owner	        = THIS_MODULE,
1328 		.name	        = MV_XOR_NAME,
1329 		.of_match_table = of_match_ptr(mv_xor_dt_ids),
1330 	},
1331 };
1332 
1333 
1334 static int __init mv_xor_init(void)
1335 {
1336 	return platform_driver_register(&mv_xor_driver);
1337 }
1338 module_init(mv_xor_init);
1339 
1340 /* it's currently unsafe to unload this module */
1341 #if 0
1342 static void __exit mv_xor_exit(void)
1343 {
1344 	platform_driver_unregister(&mv_xor_driver);
1345 	return;
1346 }
1347 
1348 module_exit(mv_xor_exit);
1349 #endif
1350 
1351 MODULE_AUTHOR("Saeed Bishara <saeed@marvell.com>");
1352 MODULE_DESCRIPTION("DMA engine driver for Marvell's XOR engine");
1353 MODULE_LICENSE("GPL");
1354