xref: /openbmc/linux/drivers/dma/moxart-dma.c (revision d9fd5a71)
1 /*
2  * MOXA ART SoCs DMA Engine support.
3  *
4  * Copyright (C) 2013 Jonas Jensen
5  *
6  * Jonas Jensen <jonas.jensen@gmail.com>
7  *
8  * This file is licensed under the terms of the GNU General Public
9  * License version 2.  This program is licensed "as is" without any
10  * warranty of any kind, whether express or implied.
11  */
12 
13 #include <linux/dmaengine.h>
14 #include <linux/dma-mapping.h>
15 #include <linux/err.h>
16 #include <linux/init.h>
17 #include <linux/interrupt.h>
18 #include <linux/list.h>
19 #include <linux/module.h>
20 #include <linux/platform_device.h>
21 #include <linux/slab.h>
22 #include <linux/spinlock.h>
23 #include <linux/of_address.h>
24 #include <linux/of_irq.h>
25 #include <linux/of_dma.h>
26 #include <linux/bitops.h>
27 
28 #include <asm/cacheflush.h>
29 
30 #include "dmaengine.h"
31 #include "virt-dma.h"
32 
33 #define APB_DMA_MAX_CHANNEL			4
34 
35 #define REG_OFF_ADDRESS_SOURCE			0
36 #define REG_OFF_ADDRESS_DEST			4
37 #define REG_OFF_CYCLES				8
38 #define REG_OFF_CTRL				12
39 #define REG_OFF_CHAN_SIZE			16
40 
41 #define APB_DMA_ENABLE				BIT(0)
42 #define APB_DMA_FIN_INT_STS			BIT(1)
43 #define APB_DMA_FIN_INT_EN			BIT(2)
44 #define APB_DMA_BURST_MODE			BIT(3)
45 #define APB_DMA_ERR_INT_STS			BIT(4)
46 #define APB_DMA_ERR_INT_EN			BIT(5)
47 
48 /*
49  * Unset: APB
50  * Set:   AHB
51  */
52 #define APB_DMA_SOURCE_SELECT			0x40
53 #define APB_DMA_DEST_SELECT			0x80
54 
55 #define APB_DMA_SOURCE				0x100
56 #define APB_DMA_DEST				0x1000
57 
58 #define APB_DMA_SOURCE_MASK			0x700
59 #define APB_DMA_DEST_MASK			0x7000
60 
61 /*
62  * 000: No increment
63  * 001: +1 (Burst=0), +4  (Burst=1)
64  * 010: +2 (Burst=0), +8  (Burst=1)
65  * 011: +4 (Burst=0), +16 (Burst=1)
66  * 101: -1 (Burst=0), -4  (Burst=1)
67  * 110: -2 (Burst=0), -8  (Burst=1)
68  * 111: -4 (Burst=0), -16 (Burst=1)
69  */
70 #define APB_DMA_SOURCE_INC_0			0
71 #define APB_DMA_SOURCE_INC_1_4			0x100
72 #define APB_DMA_SOURCE_INC_2_8			0x200
73 #define APB_DMA_SOURCE_INC_4_16			0x300
74 #define APB_DMA_SOURCE_DEC_1_4			0x500
75 #define APB_DMA_SOURCE_DEC_2_8			0x600
76 #define APB_DMA_SOURCE_DEC_4_16			0x700
77 #define APB_DMA_DEST_INC_0			0
78 #define APB_DMA_DEST_INC_1_4			0x1000
79 #define APB_DMA_DEST_INC_2_8			0x2000
80 #define APB_DMA_DEST_INC_4_16			0x3000
81 #define APB_DMA_DEST_DEC_1_4			0x5000
82 #define APB_DMA_DEST_DEC_2_8			0x6000
83 #define APB_DMA_DEST_DEC_4_16			0x7000
84 
85 /*
86  * Request signal select source/destination address for DMA hardware handshake.
87  *
88  * The request line number is a property of the DMA controller itself,
89  * e.g. MMC must always request channels where dma_slave_config->slave_id is 5.
90  *
91  * 0:    No request / Grant signal
92  * 1-15: Request    / Grant signal
93  */
94 #define APB_DMA_SOURCE_REQ_NO			0x1000000
95 #define APB_DMA_SOURCE_REQ_NO_MASK		0xf000000
96 #define APB_DMA_DEST_REQ_NO			0x10000
97 #define APB_DMA_DEST_REQ_NO_MASK		0xf0000
98 
99 #define APB_DMA_DATA_WIDTH			0x100000
100 #define APB_DMA_DATA_WIDTH_MASK			0x300000
101 /*
102  * Data width of transfer:
103  *
104  * 00: Word
105  * 01: Half
106  * 10: Byte
107  */
108 #define APB_DMA_DATA_WIDTH_4			0
109 #define APB_DMA_DATA_WIDTH_2			0x100000
110 #define APB_DMA_DATA_WIDTH_1			0x200000
111 
112 #define APB_DMA_CYCLES_MASK			0x00ffffff
113 
114 #define MOXART_DMA_DATA_TYPE_S8			0x00
115 #define MOXART_DMA_DATA_TYPE_S16		0x01
116 #define MOXART_DMA_DATA_TYPE_S32		0x02
117 
118 struct moxart_sg {
119 	dma_addr_t addr;
120 	uint32_t len;
121 };
122 
123 struct moxart_desc {
124 	enum dma_transfer_direction	dma_dir;
125 	dma_addr_t			dev_addr;
126 	unsigned int			sglen;
127 	unsigned int			dma_cycles;
128 	struct virt_dma_desc		vd;
129 	uint8_t				es;
130 	struct moxart_sg		sg[];
131 };
132 
133 struct moxart_chan {
134 	struct virt_dma_chan		vc;
135 
136 	void __iomem			*base;
137 	struct moxart_desc		*desc;
138 
139 	struct dma_slave_config		cfg;
140 
141 	bool				allocated;
142 	bool				error;
143 	int				ch_num;
144 	unsigned int			line_reqno;
145 	unsigned int			sgidx;
146 };
147 
148 struct moxart_dmadev {
149 	struct dma_device		dma_slave;
150 	struct moxart_chan		slave_chans[APB_DMA_MAX_CHANNEL];
151 	unsigned int			irq;
152 };
153 
154 struct moxart_filter_data {
155 	struct moxart_dmadev		*mdc;
156 	struct of_phandle_args		*dma_spec;
157 };
158 
159 static const unsigned int es_bytes[] = {
160 	[MOXART_DMA_DATA_TYPE_S8] = 1,
161 	[MOXART_DMA_DATA_TYPE_S16] = 2,
162 	[MOXART_DMA_DATA_TYPE_S32] = 4,
163 };
164 
165 static struct device *chan2dev(struct dma_chan *chan)
166 {
167 	return &chan->dev->device;
168 }
169 
170 static inline struct moxart_chan *to_moxart_dma_chan(struct dma_chan *c)
171 {
172 	return container_of(c, struct moxart_chan, vc.chan);
173 }
174 
175 static inline struct moxart_desc *to_moxart_dma_desc(
176 	struct dma_async_tx_descriptor *t)
177 {
178 	return container_of(t, struct moxart_desc, vd.tx);
179 }
180 
181 static void moxart_dma_desc_free(struct virt_dma_desc *vd)
182 {
183 	kfree(container_of(vd, struct moxart_desc, vd));
184 }
185 
186 static int moxart_terminate_all(struct dma_chan *chan)
187 {
188 	struct moxart_chan *ch = to_moxart_dma_chan(chan);
189 	unsigned long flags;
190 	LIST_HEAD(head);
191 	u32 ctrl;
192 
193 	dev_dbg(chan2dev(chan), "%s: ch=%p\n", __func__, ch);
194 
195 	spin_lock_irqsave(&ch->vc.lock, flags);
196 
197 	if (ch->desc) {
198 		moxart_dma_desc_free(&ch->desc->vd);
199 		ch->desc = NULL;
200 	}
201 
202 	ctrl = readl(ch->base + REG_OFF_CTRL);
203 	ctrl &= ~(APB_DMA_ENABLE | APB_DMA_FIN_INT_EN | APB_DMA_ERR_INT_EN);
204 	writel(ctrl, ch->base + REG_OFF_CTRL);
205 
206 	vchan_get_all_descriptors(&ch->vc, &head);
207 	spin_unlock_irqrestore(&ch->vc.lock, flags);
208 	vchan_dma_desc_free_list(&ch->vc, &head);
209 
210 	return 0;
211 }
212 
213 static int moxart_slave_config(struct dma_chan *chan,
214 			       struct dma_slave_config *cfg)
215 {
216 	struct moxart_chan *ch = to_moxart_dma_chan(chan);
217 	u32 ctrl;
218 
219 	ch->cfg = *cfg;
220 
221 	ctrl = readl(ch->base + REG_OFF_CTRL);
222 	ctrl |= APB_DMA_BURST_MODE;
223 	ctrl &= ~(APB_DMA_DEST_MASK | APB_DMA_SOURCE_MASK);
224 	ctrl &= ~(APB_DMA_DEST_REQ_NO_MASK | APB_DMA_SOURCE_REQ_NO_MASK);
225 
226 	switch (ch->cfg.src_addr_width) {
227 	case DMA_SLAVE_BUSWIDTH_1_BYTE:
228 		ctrl |= APB_DMA_DATA_WIDTH_1;
229 		if (ch->cfg.direction != DMA_MEM_TO_DEV)
230 			ctrl |= APB_DMA_DEST_INC_1_4;
231 		else
232 			ctrl |= APB_DMA_SOURCE_INC_1_4;
233 		break;
234 	case DMA_SLAVE_BUSWIDTH_2_BYTES:
235 		ctrl |= APB_DMA_DATA_WIDTH_2;
236 		if (ch->cfg.direction != DMA_MEM_TO_DEV)
237 			ctrl |= APB_DMA_DEST_INC_2_8;
238 		else
239 			ctrl |= APB_DMA_SOURCE_INC_2_8;
240 		break;
241 	case DMA_SLAVE_BUSWIDTH_4_BYTES:
242 		ctrl &= ~APB_DMA_DATA_WIDTH;
243 		if (ch->cfg.direction != DMA_MEM_TO_DEV)
244 			ctrl |= APB_DMA_DEST_INC_4_16;
245 		else
246 			ctrl |= APB_DMA_SOURCE_INC_4_16;
247 		break;
248 	default:
249 		return -EINVAL;
250 	}
251 
252 	if (ch->cfg.direction == DMA_MEM_TO_DEV) {
253 		ctrl &= ~APB_DMA_DEST_SELECT;
254 		ctrl |= APB_DMA_SOURCE_SELECT;
255 		ctrl |= (ch->line_reqno << 16 &
256 			 APB_DMA_DEST_REQ_NO_MASK);
257 	} else {
258 		ctrl |= APB_DMA_DEST_SELECT;
259 		ctrl &= ~APB_DMA_SOURCE_SELECT;
260 		ctrl |= (ch->line_reqno << 24 &
261 			 APB_DMA_SOURCE_REQ_NO_MASK);
262 	}
263 
264 	writel(ctrl, ch->base + REG_OFF_CTRL);
265 
266 	return 0;
267 }
268 
269 static struct dma_async_tx_descriptor *moxart_prep_slave_sg(
270 	struct dma_chan *chan, struct scatterlist *sgl,
271 	unsigned int sg_len, enum dma_transfer_direction dir,
272 	unsigned long tx_flags, void *context)
273 {
274 	struct moxart_chan *ch = to_moxart_dma_chan(chan);
275 	struct moxart_desc *d;
276 	enum dma_slave_buswidth dev_width;
277 	dma_addr_t dev_addr;
278 	struct scatterlist *sgent;
279 	unsigned int es;
280 	unsigned int i;
281 
282 	if (!is_slave_direction(dir)) {
283 		dev_err(chan2dev(chan), "%s: invalid DMA direction\n",
284 			__func__);
285 		return NULL;
286 	}
287 
288 	if (dir == DMA_DEV_TO_MEM) {
289 		dev_addr = ch->cfg.src_addr;
290 		dev_width = ch->cfg.src_addr_width;
291 	} else {
292 		dev_addr = ch->cfg.dst_addr;
293 		dev_width = ch->cfg.dst_addr_width;
294 	}
295 
296 	switch (dev_width) {
297 	case DMA_SLAVE_BUSWIDTH_1_BYTE:
298 		es = MOXART_DMA_DATA_TYPE_S8;
299 		break;
300 	case DMA_SLAVE_BUSWIDTH_2_BYTES:
301 		es = MOXART_DMA_DATA_TYPE_S16;
302 		break;
303 	case DMA_SLAVE_BUSWIDTH_4_BYTES:
304 		es = MOXART_DMA_DATA_TYPE_S32;
305 		break;
306 	default:
307 		dev_err(chan2dev(chan), "%s: unsupported data width (%u)\n",
308 			__func__, dev_width);
309 		return NULL;
310 	}
311 
312 	d = kzalloc(struct_size(d, sg, sg_len), GFP_ATOMIC);
313 	if (!d)
314 		return NULL;
315 
316 	d->dma_dir = dir;
317 	d->dev_addr = dev_addr;
318 	d->es = es;
319 
320 	for_each_sg(sgl, sgent, sg_len, i) {
321 		d->sg[i].addr = sg_dma_address(sgent);
322 		d->sg[i].len = sg_dma_len(sgent);
323 	}
324 
325 	d->sglen = sg_len;
326 
327 	ch->error = 0;
328 
329 	return vchan_tx_prep(&ch->vc, &d->vd, tx_flags);
330 }
331 
332 static struct dma_chan *moxart_of_xlate(struct of_phandle_args *dma_spec,
333 					struct of_dma *ofdma)
334 {
335 	struct moxart_dmadev *mdc = ofdma->of_dma_data;
336 	struct dma_chan *chan;
337 	struct moxart_chan *ch;
338 
339 	chan = dma_get_any_slave_channel(&mdc->dma_slave);
340 	if (!chan)
341 		return NULL;
342 
343 	ch = to_moxart_dma_chan(chan);
344 	ch->line_reqno = dma_spec->args[0];
345 
346 	return chan;
347 }
348 
349 static int moxart_alloc_chan_resources(struct dma_chan *chan)
350 {
351 	struct moxart_chan *ch = to_moxart_dma_chan(chan);
352 
353 	dev_dbg(chan2dev(chan), "%s: allocating channel #%u\n",
354 		__func__, ch->ch_num);
355 	ch->allocated = 1;
356 
357 	return 0;
358 }
359 
360 static void moxart_free_chan_resources(struct dma_chan *chan)
361 {
362 	struct moxart_chan *ch = to_moxart_dma_chan(chan);
363 
364 	vchan_free_chan_resources(&ch->vc);
365 
366 	dev_dbg(chan2dev(chan), "%s: freeing channel #%u\n",
367 		__func__, ch->ch_num);
368 	ch->allocated = 0;
369 }
370 
371 static void moxart_dma_set_params(struct moxart_chan *ch, dma_addr_t src_addr,
372 				  dma_addr_t dst_addr)
373 {
374 	writel(src_addr, ch->base + REG_OFF_ADDRESS_SOURCE);
375 	writel(dst_addr, ch->base + REG_OFF_ADDRESS_DEST);
376 }
377 
378 static void moxart_set_transfer_params(struct moxart_chan *ch, unsigned int len)
379 {
380 	struct moxart_desc *d = ch->desc;
381 	unsigned int sglen_div = es_bytes[d->es];
382 
383 	d->dma_cycles = len >> sglen_div;
384 
385 	/*
386 	 * There are 4 cycles on 64 bytes copied, i.e. one cycle copies 16
387 	 * bytes ( when width is APB_DMAB_DATA_WIDTH_4 ).
388 	 */
389 	writel(d->dma_cycles, ch->base + REG_OFF_CYCLES);
390 
391 	dev_dbg(chan2dev(&ch->vc.chan), "%s: set %u DMA cycles (len=%u)\n",
392 		__func__, d->dma_cycles, len);
393 }
394 
395 static void moxart_start_dma(struct moxart_chan *ch)
396 {
397 	u32 ctrl;
398 
399 	ctrl = readl(ch->base + REG_OFF_CTRL);
400 	ctrl |= (APB_DMA_ENABLE | APB_DMA_FIN_INT_EN | APB_DMA_ERR_INT_EN);
401 	writel(ctrl, ch->base + REG_OFF_CTRL);
402 }
403 
404 static void moxart_dma_start_sg(struct moxart_chan *ch, unsigned int idx)
405 {
406 	struct moxart_desc *d = ch->desc;
407 	struct moxart_sg *sg = ch->desc->sg + idx;
408 
409 	if (ch->desc->dma_dir == DMA_MEM_TO_DEV)
410 		moxart_dma_set_params(ch, sg->addr, d->dev_addr);
411 	else if (ch->desc->dma_dir == DMA_DEV_TO_MEM)
412 		moxart_dma_set_params(ch, d->dev_addr, sg->addr);
413 
414 	moxart_set_transfer_params(ch, sg->len);
415 
416 	moxart_start_dma(ch);
417 }
418 
419 static void moxart_dma_start_desc(struct dma_chan *chan)
420 {
421 	struct moxart_chan *ch = to_moxart_dma_chan(chan);
422 	struct virt_dma_desc *vd;
423 
424 	vd = vchan_next_desc(&ch->vc);
425 
426 	if (!vd) {
427 		ch->desc = NULL;
428 		return;
429 	}
430 
431 	list_del(&vd->node);
432 
433 	ch->desc = to_moxart_dma_desc(&vd->tx);
434 	ch->sgidx = 0;
435 
436 	moxart_dma_start_sg(ch, 0);
437 }
438 
439 static void moxart_issue_pending(struct dma_chan *chan)
440 {
441 	struct moxart_chan *ch = to_moxart_dma_chan(chan);
442 	unsigned long flags;
443 
444 	spin_lock_irqsave(&ch->vc.lock, flags);
445 	if (vchan_issue_pending(&ch->vc) && !ch->desc)
446 		moxart_dma_start_desc(chan);
447 	spin_unlock_irqrestore(&ch->vc.lock, flags);
448 }
449 
450 static size_t moxart_dma_desc_size(struct moxart_desc *d,
451 				   unsigned int completed_sgs)
452 {
453 	unsigned int i;
454 	size_t size;
455 
456 	for (size = i = completed_sgs; i < d->sglen; i++)
457 		size += d->sg[i].len;
458 
459 	return size;
460 }
461 
462 static size_t moxart_dma_desc_size_in_flight(struct moxart_chan *ch)
463 {
464 	size_t size;
465 	unsigned int completed_cycles, cycles;
466 
467 	size = moxart_dma_desc_size(ch->desc, ch->sgidx);
468 	cycles = readl(ch->base + REG_OFF_CYCLES);
469 	completed_cycles = (ch->desc->dma_cycles - cycles);
470 	size -= completed_cycles << es_bytes[ch->desc->es];
471 
472 	dev_dbg(chan2dev(&ch->vc.chan), "%s: size=%zu\n", __func__, size);
473 
474 	return size;
475 }
476 
477 static enum dma_status moxart_tx_status(struct dma_chan *chan,
478 					dma_cookie_t cookie,
479 					struct dma_tx_state *txstate)
480 {
481 	struct moxart_chan *ch = to_moxart_dma_chan(chan);
482 	struct virt_dma_desc *vd;
483 	struct moxart_desc *d;
484 	enum dma_status ret;
485 	unsigned long flags;
486 
487 	/*
488 	 * dma_cookie_status() assigns initial residue value.
489 	 */
490 	ret = dma_cookie_status(chan, cookie, txstate);
491 
492 	spin_lock_irqsave(&ch->vc.lock, flags);
493 	vd = vchan_find_desc(&ch->vc, cookie);
494 	if (vd) {
495 		d = to_moxart_dma_desc(&vd->tx);
496 		txstate->residue = moxart_dma_desc_size(d, 0);
497 	} else if (ch->desc && ch->desc->vd.tx.cookie == cookie) {
498 		txstate->residue = moxart_dma_desc_size_in_flight(ch);
499 	}
500 	spin_unlock_irqrestore(&ch->vc.lock, flags);
501 
502 	if (ch->error)
503 		return DMA_ERROR;
504 
505 	return ret;
506 }
507 
508 static void moxart_dma_init(struct dma_device *dma, struct device *dev)
509 {
510 	dma->device_prep_slave_sg		= moxart_prep_slave_sg;
511 	dma->device_alloc_chan_resources	= moxart_alloc_chan_resources;
512 	dma->device_free_chan_resources		= moxart_free_chan_resources;
513 	dma->device_issue_pending		= moxart_issue_pending;
514 	dma->device_tx_status			= moxart_tx_status;
515 	dma->device_config			= moxart_slave_config;
516 	dma->device_terminate_all		= moxart_terminate_all;
517 	dma->dev				= dev;
518 
519 	INIT_LIST_HEAD(&dma->channels);
520 }
521 
522 static irqreturn_t moxart_dma_interrupt(int irq, void *devid)
523 {
524 	struct moxart_dmadev *mc = devid;
525 	struct moxart_chan *ch = &mc->slave_chans[0];
526 	unsigned int i;
527 	u32 ctrl;
528 
529 	dev_dbg(chan2dev(&ch->vc.chan), "%s\n", __func__);
530 
531 	for (i = 0; i < APB_DMA_MAX_CHANNEL; i++, ch++) {
532 		if (!ch->allocated)
533 			continue;
534 
535 		ctrl = readl(ch->base + REG_OFF_CTRL);
536 
537 		dev_dbg(chan2dev(&ch->vc.chan), "%s: ch=%p ch->base=%p ctrl=%x\n",
538 			__func__, ch, ch->base, ctrl);
539 
540 		if (ctrl & APB_DMA_FIN_INT_STS) {
541 			ctrl &= ~APB_DMA_FIN_INT_STS;
542 			if (ch->desc) {
543 				spin_lock(&ch->vc.lock);
544 				if (++ch->sgidx < ch->desc->sglen) {
545 					moxart_dma_start_sg(ch, ch->sgidx);
546 				} else {
547 					vchan_cookie_complete(&ch->desc->vd);
548 					moxart_dma_start_desc(&ch->vc.chan);
549 				}
550 				spin_unlock(&ch->vc.lock);
551 			}
552 		}
553 
554 		if (ctrl & APB_DMA_ERR_INT_STS) {
555 			ctrl &= ~APB_DMA_ERR_INT_STS;
556 			ch->error = 1;
557 		}
558 
559 		writel(ctrl, ch->base + REG_OFF_CTRL);
560 	}
561 
562 	return IRQ_HANDLED;
563 }
564 
565 static int moxart_probe(struct platform_device *pdev)
566 {
567 	struct device *dev = &pdev->dev;
568 	struct device_node *node = dev->of_node;
569 	struct resource *res;
570 	void __iomem *dma_base_addr;
571 	int ret, i;
572 	unsigned int irq;
573 	struct moxart_chan *ch;
574 	struct moxart_dmadev *mdc;
575 
576 	mdc = devm_kzalloc(dev, sizeof(*mdc), GFP_KERNEL);
577 	if (!mdc)
578 		return -ENOMEM;
579 
580 	irq = irq_of_parse_and_map(node, 0);
581 	if (!irq) {
582 		dev_err(dev, "no IRQ resource\n");
583 		return -EINVAL;
584 	}
585 
586 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
587 	dma_base_addr = devm_ioremap_resource(dev, res);
588 	if (IS_ERR(dma_base_addr))
589 		return PTR_ERR(dma_base_addr);
590 
591 	dma_cap_zero(mdc->dma_slave.cap_mask);
592 	dma_cap_set(DMA_SLAVE, mdc->dma_slave.cap_mask);
593 	dma_cap_set(DMA_PRIVATE, mdc->dma_slave.cap_mask);
594 
595 	moxart_dma_init(&mdc->dma_slave, dev);
596 
597 	ch = &mdc->slave_chans[0];
598 	for (i = 0; i < APB_DMA_MAX_CHANNEL; i++, ch++) {
599 		ch->ch_num = i;
600 		ch->base = dma_base_addr + i * REG_OFF_CHAN_SIZE;
601 		ch->allocated = 0;
602 
603 		ch->vc.desc_free = moxart_dma_desc_free;
604 		vchan_init(&ch->vc, &mdc->dma_slave);
605 
606 		dev_dbg(dev, "%s: chs[%d]: ch->ch_num=%u ch->base=%p\n",
607 			__func__, i, ch->ch_num, ch->base);
608 	}
609 
610 	platform_set_drvdata(pdev, mdc);
611 
612 	ret = devm_request_irq(dev, irq, moxart_dma_interrupt, 0,
613 			       "moxart-dma-engine", mdc);
614 	if (ret) {
615 		dev_err(dev, "devm_request_irq failed\n");
616 		return ret;
617 	}
618 	mdc->irq = irq;
619 
620 	ret = dma_async_device_register(&mdc->dma_slave);
621 	if (ret) {
622 		dev_err(dev, "dma_async_device_register failed\n");
623 		return ret;
624 	}
625 
626 	ret = of_dma_controller_register(node, moxart_of_xlate, mdc);
627 	if (ret) {
628 		dev_err(dev, "of_dma_controller_register failed\n");
629 		dma_async_device_unregister(&mdc->dma_slave);
630 		return ret;
631 	}
632 
633 	dev_dbg(dev, "%s: IRQ=%u\n", __func__, irq);
634 
635 	return 0;
636 }
637 
638 static int moxart_remove(struct platform_device *pdev)
639 {
640 	struct moxart_dmadev *m = platform_get_drvdata(pdev);
641 
642 	devm_free_irq(&pdev->dev, m->irq, m);
643 
644 	dma_async_device_unregister(&m->dma_slave);
645 
646 	if (pdev->dev.of_node)
647 		of_dma_controller_free(pdev->dev.of_node);
648 
649 	return 0;
650 }
651 
652 static const struct of_device_id moxart_dma_match[] = {
653 	{ .compatible = "moxa,moxart-dma" },
654 	{ }
655 };
656 MODULE_DEVICE_TABLE(of, moxart_dma_match);
657 
658 static struct platform_driver moxart_driver = {
659 	.probe	= moxart_probe,
660 	.remove	= moxart_remove,
661 	.driver = {
662 		.name		= "moxart-dma-engine",
663 		.of_match_table	= moxart_dma_match,
664 	},
665 };
666 
667 static int moxart_init(void)
668 {
669 	return platform_driver_register(&moxart_driver);
670 }
671 subsys_initcall(moxart_init);
672 
673 static void __exit moxart_exit(void)
674 {
675 	platform_driver_unregister(&moxart_driver);
676 }
677 module_exit(moxart_exit);
678 
679 MODULE_AUTHOR("Jonas Jensen <jonas.jensen@gmail.com>");
680 MODULE_DESCRIPTION("MOXART DMA engine driver");
681 MODULE_LICENSE("GPL v2");
682