xref: /openbmc/linux/drivers/dma/moxart-dma.c (revision e79e40c8)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * MOXA ART SoCs DMA Engine support.
4  *
5  * Copyright (C) 2013 Jonas Jensen
6  *
7  * Jonas Jensen <jonas.jensen@gmail.com>
8  */
9 
10 #include <linux/dmaengine.h>
11 #include <linux/dma-mapping.h>
12 #include <linux/err.h>
13 #include <linux/init.h>
14 #include <linux/interrupt.h>
15 #include <linux/list.h>
16 #include <linux/module.h>
17 #include <linux/platform_device.h>
18 #include <linux/slab.h>
19 #include <linux/spinlock.h>
20 #include <linux/of_address.h>
21 #include <linux/of_irq.h>
22 #include <linux/of_dma.h>
23 #include <linux/bitops.h>
24 
25 #include <asm/cacheflush.h>
26 
27 #include "dmaengine.h"
28 #include "virt-dma.h"
29 
30 #define APB_DMA_MAX_CHANNEL			4
31 
32 #define REG_OFF_ADDRESS_SOURCE			0
33 #define REG_OFF_ADDRESS_DEST			4
34 #define REG_OFF_CYCLES				8
35 #define REG_OFF_CTRL				12
36 #define REG_OFF_CHAN_SIZE			16
37 
38 #define APB_DMA_ENABLE				BIT(0)
39 #define APB_DMA_FIN_INT_STS			BIT(1)
40 #define APB_DMA_FIN_INT_EN			BIT(2)
41 #define APB_DMA_BURST_MODE			BIT(3)
42 #define APB_DMA_ERR_INT_STS			BIT(4)
43 #define APB_DMA_ERR_INT_EN			BIT(5)
44 
45 /*
46  * Unset: APB
47  * Set:   AHB
48  */
49 #define APB_DMA_SOURCE_SELECT			0x40
50 #define APB_DMA_DEST_SELECT			0x80
51 
52 #define APB_DMA_SOURCE				0x100
53 #define APB_DMA_DEST				0x1000
54 
55 #define APB_DMA_SOURCE_MASK			0x700
56 #define APB_DMA_DEST_MASK			0x7000
57 
58 /*
59  * 000: No increment
60  * 001: +1 (Burst=0), +4  (Burst=1)
61  * 010: +2 (Burst=0), +8  (Burst=1)
62  * 011: +4 (Burst=0), +16 (Burst=1)
63  * 101: -1 (Burst=0), -4  (Burst=1)
64  * 110: -2 (Burst=0), -8  (Burst=1)
65  * 111: -4 (Burst=0), -16 (Burst=1)
66  */
67 #define APB_DMA_SOURCE_INC_0			0
68 #define APB_DMA_SOURCE_INC_1_4			0x100
69 #define APB_DMA_SOURCE_INC_2_8			0x200
70 #define APB_DMA_SOURCE_INC_4_16			0x300
71 #define APB_DMA_SOURCE_DEC_1_4			0x500
72 #define APB_DMA_SOURCE_DEC_2_8			0x600
73 #define APB_DMA_SOURCE_DEC_4_16			0x700
74 #define APB_DMA_DEST_INC_0			0
75 #define APB_DMA_DEST_INC_1_4			0x1000
76 #define APB_DMA_DEST_INC_2_8			0x2000
77 #define APB_DMA_DEST_INC_4_16			0x3000
78 #define APB_DMA_DEST_DEC_1_4			0x5000
79 #define APB_DMA_DEST_DEC_2_8			0x6000
80 #define APB_DMA_DEST_DEC_4_16			0x7000
81 
82 /*
83  * Request signal select source/destination address for DMA hardware handshake.
84  *
85  * The request line number is a property of the DMA controller itself,
86  * e.g. MMC must always request channels where dma_slave_config->slave_id is 5.
87  *
88  * 0:    No request / Grant signal
89  * 1-15: Request    / Grant signal
90  */
91 #define APB_DMA_SOURCE_REQ_NO			0x1000000
92 #define APB_DMA_SOURCE_REQ_NO_MASK		0xf000000
93 #define APB_DMA_DEST_REQ_NO			0x10000
94 #define APB_DMA_DEST_REQ_NO_MASK		0xf0000
95 
96 #define APB_DMA_DATA_WIDTH			0x100000
97 #define APB_DMA_DATA_WIDTH_MASK			0x300000
98 /*
99  * Data width of transfer:
100  *
101  * 00: Word
102  * 01: Half
103  * 10: Byte
104  */
105 #define APB_DMA_DATA_WIDTH_4			0
106 #define APB_DMA_DATA_WIDTH_2			0x100000
107 #define APB_DMA_DATA_WIDTH_1			0x200000
108 
109 #define APB_DMA_CYCLES_MASK			0x00ffffff
110 
111 #define MOXART_DMA_DATA_TYPE_S8			0x00
112 #define MOXART_DMA_DATA_TYPE_S16		0x01
113 #define MOXART_DMA_DATA_TYPE_S32		0x02
114 
115 struct moxart_sg {
116 	dma_addr_t addr;
117 	uint32_t len;
118 };
119 
120 struct moxart_desc {
121 	enum dma_transfer_direction	dma_dir;
122 	dma_addr_t			dev_addr;
123 	unsigned int			sglen;
124 	unsigned int			dma_cycles;
125 	struct virt_dma_desc		vd;
126 	uint8_t				es;
127 	struct moxart_sg		sg[];
128 };
129 
130 struct moxart_chan {
131 	struct virt_dma_chan		vc;
132 
133 	void __iomem			*base;
134 	struct moxart_desc		*desc;
135 
136 	struct dma_slave_config		cfg;
137 
138 	bool				allocated;
139 	bool				error;
140 	int				ch_num;
141 	unsigned int			line_reqno;
142 	unsigned int			sgidx;
143 };
144 
145 struct moxart_dmadev {
146 	struct dma_device		dma_slave;
147 	struct moxart_chan		slave_chans[APB_DMA_MAX_CHANNEL];
148 	unsigned int			irq;
149 };
150 
151 struct moxart_filter_data {
152 	struct moxart_dmadev		*mdc;
153 	struct of_phandle_args		*dma_spec;
154 };
155 
156 static const unsigned int es_bytes[] = {
157 	[MOXART_DMA_DATA_TYPE_S8] = 1,
158 	[MOXART_DMA_DATA_TYPE_S16] = 2,
159 	[MOXART_DMA_DATA_TYPE_S32] = 4,
160 };
161 
162 static struct device *chan2dev(struct dma_chan *chan)
163 {
164 	return &chan->dev->device;
165 }
166 
167 static inline struct moxart_chan *to_moxart_dma_chan(struct dma_chan *c)
168 {
169 	return container_of(c, struct moxart_chan, vc.chan);
170 }
171 
172 static inline struct moxart_desc *to_moxart_dma_desc(
173 	struct dma_async_tx_descriptor *t)
174 {
175 	return container_of(t, struct moxart_desc, vd.tx);
176 }
177 
178 static void moxart_dma_desc_free(struct virt_dma_desc *vd)
179 {
180 	kfree(container_of(vd, struct moxart_desc, vd));
181 }
182 
183 static int moxart_terminate_all(struct dma_chan *chan)
184 {
185 	struct moxart_chan *ch = to_moxart_dma_chan(chan);
186 	unsigned long flags;
187 	LIST_HEAD(head);
188 	u32 ctrl;
189 
190 	dev_dbg(chan2dev(chan), "%s: ch=%p\n", __func__, ch);
191 
192 	spin_lock_irqsave(&ch->vc.lock, flags);
193 
194 	if (ch->desc) {
195 		moxart_dma_desc_free(&ch->desc->vd);
196 		ch->desc = NULL;
197 	}
198 
199 	ctrl = readl(ch->base + REG_OFF_CTRL);
200 	ctrl &= ~(APB_DMA_ENABLE | APB_DMA_FIN_INT_EN | APB_DMA_ERR_INT_EN);
201 	writel(ctrl, ch->base + REG_OFF_CTRL);
202 
203 	vchan_get_all_descriptors(&ch->vc, &head);
204 	spin_unlock_irqrestore(&ch->vc.lock, flags);
205 	vchan_dma_desc_free_list(&ch->vc, &head);
206 
207 	return 0;
208 }
209 
210 static int moxart_slave_config(struct dma_chan *chan,
211 			       struct dma_slave_config *cfg)
212 {
213 	struct moxart_chan *ch = to_moxart_dma_chan(chan);
214 	u32 ctrl;
215 
216 	ch->cfg = *cfg;
217 
218 	ctrl = readl(ch->base + REG_OFF_CTRL);
219 	ctrl |= APB_DMA_BURST_MODE;
220 	ctrl &= ~(APB_DMA_DEST_MASK | APB_DMA_SOURCE_MASK);
221 	ctrl &= ~(APB_DMA_DEST_REQ_NO_MASK | APB_DMA_SOURCE_REQ_NO_MASK);
222 
223 	switch (ch->cfg.src_addr_width) {
224 	case DMA_SLAVE_BUSWIDTH_1_BYTE:
225 		ctrl |= APB_DMA_DATA_WIDTH_1;
226 		if (ch->cfg.direction != DMA_MEM_TO_DEV)
227 			ctrl |= APB_DMA_DEST_INC_1_4;
228 		else
229 			ctrl |= APB_DMA_SOURCE_INC_1_4;
230 		break;
231 	case DMA_SLAVE_BUSWIDTH_2_BYTES:
232 		ctrl |= APB_DMA_DATA_WIDTH_2;
233 		if (ch->cfg.direction != DMA_MEM_TO_DEV)
234 			ctrl |= APB_DMA_DEST_INC_2_8;
235 		else
236 			ctrl |= APB_DMA_SOURCE_INC_2_8;
237 		break;
238 	case DMA_SLAVE_BUSWIDTH_4_BYTES:
239 		ctrl &= ~APB_DMA_DATA_WIDTH;
240 		if (ch->cfg.direction != DMA_MEM_TO_DEV)
241 			ctrl |= APB_DMA_DEST_INC_4_16;
242 		else
243 			ctrl |= APB_DMA_SOURCE_INC_4_16;
244 		break;
245 	default:
246 		return -EINVAL;
247 	}
248 
249 	if (ch->cfg.direction == DMA_MEM_TO_DEV) {
250 		ctrl &= ~APB_DMA_DEST_SELECT;
251 		ctrl |= APB_DMA_SOURCE_SELECT;
252 		ctrl |= (ch->line_reqno << 16 &
253 			 APB_DMA_DEST_REQ_NO_MASK);
254 	} else {
255 		ctrl |= APB_DMA_DEST_SELECT;
256 		ctrl &= ~APB_DMA_SOURCE_SELECT;
257 		ctrl |= (ch->line_reqno << 24 &
258 			 APB_DMA_SOURCE_REQ_NO_MASK);
259 	}
260 
261 	writel(ctrl, ch->base + REG_OFF_CTRL);
262 
263 	return 0;
264 }
265 
266 static struct dma_async_tx_descriptor *moxart_prep_slave_sg(
267 	struct dma_chan *chan, struct scatterlist *sgl,
268 	unsigned int sg_len, enum dma_transfer_direction dir,
269 	unsigned long tx_flags, void *context)
270 {
271 	struct moxart_chan *ch = to_moxart_dma_chan(chan);
272 	struct moxart_desc *d;
273 	enum dma_slave_buswidth dev_width;
274 	dma_addr_t dev_addr;
275 	struct scatterlist *sgent;
276 	unsigned int es;
277 	unsigned int i;
278 
279 	if (!is_slave_direction(dir)) {
280 		dev_err(chan2dev(chan), "%s: invalid DMA direction\n",
281 			__func__);
282 		return NULL;
283 	}
284 
285 	if (dir == DMA_DEV_TO_MEM) {
286 		dev_addr = ch->cfg.src_addr;
287 		dev_width = ch->cfg.src_addr_width;
288 	} else {
289 		dev_addr = ch->cfg.dst_addr;
290 		dev_width = ch->cfg.dst_addr_width;
291 	}
292 
293 	switch (dev_width) {
294 	case DMA_SLAVE_BUSWIDTH_1_BYTE:
295 		es = MOXART_DMA_DATA_TYPE_S8;
296 		break;
297 	case DMA_SLAVE_BUSWIDTH_2_BYTES:
298 		es = MOXART_DMA_DATA_TYPE_S16;
299 		break;
300 	case DMA_SLAVE_BUSWIDTH_4_BYTES:
301 		es = MOXART_DMA_DATA_TYPE_S32;
302 		break;
303 	default:
304 		dev_err(chan2dev(chan), "%s: unsupported data width (%u)\n",
305 			__func__, dev_width);
306 		return NULL;
307 	}
308 
309 	d = kzalloc(struct_size(d, sg, sg_len), GFP_ATOMIC);
310 	if (!d)
311 		return NULL;
312 
313 	d->dma_dir = dir;
314 	d->dev_addr = dev_addr;
315 	d->es = es;
316 
317 	for_each_sg(sgl, sgent, sg_len, i) {
318 		d->sg[i].addr = sg_dma_address(sgent);
319 		d->sg[i].len = sg_dma_len(sgent);
320 	}
321 
322 	d->sglen = sg_len;
323 
324 	ch->error = 0;
325 
326 	return vchan_tx_prep(&ch->vc, &d->vd, tx_flags);
327 }
328 
329 static struct dma_chan *moxart_of_xlate(struct of_phandle_args *dma_spec,
330 					struct of_dma *ofdma)
331 {
332 	struct moxart_dmadev *mdc = ofdma->of_dma_data;
333 	struct dma_chan *chan;
334 	struct moxart_chan *ch;
335 
336 	chan = dma_get_any_slave_channel(&mdc->dma_slave);
337 	if (!chan)
338 		return NULL;
339 
340 	ch = to_moxart_dma_chan(chan);
341 	ch->line_reqno = dma_spec->args[0];
342 
343 	return chan;
344 }
345 
346 static int moxart_alloc_chan_resources(struct dma_chan *chan)
347 {
348 	struct moxart_chan *ch = to_moxart_dma_chan(chan);
349 
350 	dev_dbg(chan2dev(chan), "%s: allocating channel #%u\n",
351 		__func__, ch->ch_num);
352 	ch->allocated = 1;
353 
354 	return 0;
355 }
356 
357 static void moxart_free_chan_resources(struct dma_chan *chan)
358 {
359 	struct moxart_chan *ch = to_moxart_dma_chan(chan);
360 
361 	vchan_free_chan_resources(&ch->vc);
362 
363 	dev_dbg(chan2dev(chan), "%s: freeing channel #%u\n",
364 		__func__, ch->ch_num);
365 	ch->allocated = 0;
366 }
367 
368 static void moxart_dma_set_params(struct moxart_chan *ch, dma_addr_t src_addr,
369 				  dma_addr_t dst_addr)
370 {
371 	writel(src_addr, ch->base + REG_OFF_ADDRESS_SOURCE);
372 	writel(dst_addr, ch->base + REG_OFF_ADDRESS_DEST);
373 }
374 
375 static void moxart_set_transfer_params(struct moxart_chan *ch, unsigned int len)
376 {
377 	struct moxart_desc *d = ch->desc;
378 	unsigned int sglen_div = es_bytes[d->es];
379 
380 	d->dma_cycles = len >> sglen_div;
381 
382 	/*
383 	 * There are 4 cycles on 64 bytes copied, i.e. one cycle copies 16
384 	 * bytes ( when width is APB_DMAB_DATA_WIDTH_4 ).
385 	 */
386 	writel(d->dma_cycles, ch->base + REG_OFF_CYCLES);
387 
388 	dev_dbg(chan2dev(&ch->vc.chan), "%s: set %u DMA cycles (len=%u)\n",
389 		__func__, d->dma_cycles, len);
390 }
391 
392 static void moxart_start_dma(struct moxart_chan *ch)
393 {
394 	u32 ctrl;
395 
396 	ctrl = readl(ch->base + REG_OFF_CTRL);
397 	ctrl |= (APB_DMA_ENABLE | APB_DMA_FIN_INT_EN | APB_DMA_ERR_INT_EN);
398 	writel(ctrl, ch->base + REG_OFF_CTRL);
399 }
400 
401 static void moxart_dma_start_sg(struct moxart_chan *ch, unsigned int idx)
402 {
403 	struct moxart_desc *d = ch->desc;
404 	struct moxart_sg *sg = ch->desc->sg + idx;
405 
406 	if (ch->desc->dma_dir == DMA_MEM_TO_DEV)
407 		moxart_dma_set_params(ch, sg->addr, d->dev_addr);
408 	else if (ch->desc->dma_dir == DMA_DEV_TO_MEM)
409 		moxart_dma_set_params(ch, d->dev_addr, sg->addr);
410 
411 	moxart_set_transfer_params(ch, sg->len);
412 
413 	moxart_start_dma(ch);
414 }
415 
416 static void moxart_dma_start_desc(struct dma_chan *chan)
417 {
418 	struct moxart_chan *ch = to_moxart_dma_chan(chan);
419 	struct virt_dma_desc *vd;
420 
421 	vd = vchan_next_desc(&ch->vc);
422 
423 	if (!vd) {
424 		ch->desc = NULL;
425 		return;
426 	}
427 
428 	list_del(&vd->node);
429 
430 	ch->desc = to_moxart_dma_desc(&vd->tx);
431 	ch->sgidx = 0;
432 
433 	moxart_dma_start_sg(ch, 0);
434 }
435 
436 static void moxart_issue_pending(struct dma_chan *chan)
437 {
438 	struct moxart_chan *ch = to_moxart_dma_chan(chan);
439 	unsigned long flags;
440 
441 	spin_lock_irqsave(&ch->vc.lock, flags);
442 	if (vchan_issue_pending(&ch->vc) && !ch->desc)
443 		moxart_dma_start_desc(chan);
444 	spin_unlock_irqrestore(&ch->vc.lock, flags);
445 }
446 
447 static size_t moxart_dma_desc_size(struct moxart_desc *d,
448 				   unsigned int completed_sgs)
449 {
450 	unsigned int i;
451 	size_t size;
452 
453 	for (size = i = completed_sgs; i < d->sglen; i++)
454 		size += d->sg[i].len;
455 
456 	return size;
457 }
458 
459 static size_t moxart_dma_desc_size_in_flight(struct moxart_chan *ch)
460 {
461 	size_t size;
462 	unsigned int completed_cycles, cycles;
463 
464 	size = moxart_dma_desc_size(ch->desc, ch->sgidx);
465 	cycles = readl(ch->base + REG_OFF_CYCLES);
466 	completed_cycles = (ch->desc->dma_cycles - cycles);
467 	size -= completed_cycles << es_bytes[ch->desc->es];
468 
469 	dev_dbg(chan2dev(&ch->vc.chan), "%s: size=%zu\n", __func__, size);
470 
471 	return size;
472 }
473 
474 static enum dma_status moxart_tx_status(struct dma_chan *chan,
475 					dma_cookie_t cookie,
476 					struct dma_tx_state *txstate)
477 {
478 	struct moxart_chan *ch = to_moxart_dma_chan(chan);
479 	struct virt_dma_desc *vd;
480 	struct moxart_desc *d;
481 	enum dma_status ret;
482 	unsigned long flags;
483 
484 	/*
485 	 * dma_cookie_status() assigns initial residue value.
486 	 */
487 	ret = dma_cookie_status(chan, cookie, txstate);
488 
489 	spin_lock_irqsave(&ch->vc.lock, flags);
490 	vd = vchan_find_desc(&ch->vc, cookie);
491 	if (vd) {
492 		d = to_moxart_dma_desc(&vd->tx);
493 		txstate->residue = moxart_dma_desc_size(d, 0);
494 	} else if (ch->desc && ch->desc->vd.tx.cookie == cookie) {
495 		txstate->residue = moxart_dma_desc_size_in_flight(ch);
496 	}
497 	spin_unlock_irqrestore(&ch->vc.lock, flags);
498 
499 	if (ch->error)
500 		return DMA_ERROR;
501 
502 	return ret;
503 }
504 
505 static void moxart_dma_init(struct dma_device *dma, struct device *dev)
506 {
507 	dma->device_prep_slave_sg		= moxart_prep_slave_sg;
508 	dma->device_alloc_chan_resources	= moxart_alloc_chan_resources;
509 	dma->device_free_chan_resources		= moxart_free_chan_resources;
510 	dma->device_issue_pending		= moxart_issue_pending;
511 	dma->device_tx_status			= moxart_tx_status;
512 	dma->device_config			= moxart_slave_config;
513 	dma->device_terminate_all		= moxart_terminate_all;
514 	dma->dev				= dev;
515 
516 	INIT_LIST_HEAD(&dma->channels);
517 }
518 
519 static irqreturn_t moxart_dma_interrupt(int irq, void *devid)
520 {
521 	struct moxart_dmadev *mc = devid;
522 	struct moxart_chan *ch = &mc->slave_chans[0];
523 	unsigned int i;
524 	u32 ctrl;
525 
526 	dev_dbg(chan2dev(&ch->vc.chan), "%s\n", __func__);
527 
528 	for (i = 0; i < APB_DMA_MAX_CHANNEL; i++, ch++) {
529 		if (!ch->allocated)
530 			continue;
531 
532 		ctrl = readl(ch->base + REG_OFF_CTRL);
533 
534 		dev_dbg(chan2dev(&ch->vc.chan), "%s: ch=%p ch->base=%p ctrl=%x\n",
535 			__func__, ch, ch->base, ctrl);
536 
537 		if (ctrl & APB_DMA_FIN_INT_STS) {
538 			ctrl &= ~APB_DMA_FIN_INT_STS;
539 			if (ch->desc) {
540 				spin_lock(&ch->vc.lock);
541 				if (++ch->sgidx < ch->desc->sglen) {
542 					moxart_dma_start_sg(ch, ch->sgidx);
543 				} else {
544 					vchan_cookie_complete(&ch->desc->vd);
545 					moxart_dma_start_desc(&ch->vc.chan);
546 				}
547 				spin_unlock(&ch->vc.lock);
548 			}
549 		}
550 
551 		if (ctrl & APB_DMA_ERR_INT_STS) {
552 			ctrl &= ~APB_DMA_ERR_INT_STS;
553 			ch->error = 1;
554 		}
555 
556 		writel(ctrl, ch->base + REG_OFF_CTRL);
557 	}
558 
559 	return IRQ_HANDLED;
560 }
561 
562 static int moxart_probe(struct platform_device *pdev)
563 {
564 	struct device *dev = &pdev->dev;
565 	struct device_node *node = dev->of_node;
566 	struct resource *res;
567 	void __iomem *dma_base_addr;
568 	int ret, i;
569 	unsigned int irq;
570 	struct moxart_chan *ch;
571 	struct moxart_dmadev *mdc;
572 
573 	mdc = devm_kzalloc(dev, sizeof(*mdc), GFP_KERNEL);
574 	if (!mdc)
575 		return -ENOMEM;
576 
577 	irq = irq_of_parse_and_map(node, 0);
578 	if (!irq) {
579 		dev_err(dev, "no IRQ resource\n");
580 		return -EINVAL;
581 	}
582 
583 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
584 	dma_base_addr = devm_ioremap_resource(dev, res);
585 	if (IS_ERR(dma_base_addr))
586 		return PTR_ERR(dma_base_addr);
587 
588 	dma_cap_zero(mdc->dma_slave.cap_mask);
589 	dma_cap_set(DMA_SLAVE, mdc->dma_slave.cap_mask);
590 	dma_cap_set(DMA_PRIVATE, mdc->dma_slave.cap_mask);
591 
592 	moxart_dma_init(&mdc->dma_slave, dev);
593 
594 	ch = &mdc->slave_chans[0];
595 	for (i = 0; i < APB_DMA_MAX_CHANNEL; i++, ch++) {
596 		ch->ch_num = i;
597 		ch->base = dma_base_addr + i * REG_OFF_CHAN_SIZE;
598 		ch->allocated = 0;
599 
600 		ch->vc.desc_free = moxart_dma_desc_free;
601 		vchan_init(&ch->vc, &mdc->dma_slave);
602 
603 		dev_dbg(dev, "%s: chs[%d]: ch->ch_num=%u ch->base=%p\n",
604 			__func__, i, ch->ch_num, ch->base);
605 	}
606 
607 	platform_set_drvdata(pdev, mdc);
608 
609 	ret = devm_request_irq(dev, irq, moxart_dma_interrupt, 0,
610 			       "moxart-dma-engine", mdc);
611 	if (ret) {
612 		dev_err(dev, "devm_request_irq failed\n");
613 		return ret;
614 	}
615 	mdc->irq = irq;
616 
617 	ret = dma_async_device_register(&mdc->dma_slave);
618 	if (ret) {
619 		dev_err(dev, "dma_async_device_register failed\n");
620 		return ret;
621 	}
622 
623 	ret = of_dma_controller_register(node, moxart_of_xlate, mdc);
624 	if (ret) {
625 		dev_err(dev, "of_dma_controller_register failed\n");
626 		dma_async_device_unregister(&mdc->dma_slave);
627 		return ret;
628 	}
629 
630 	dev_dbg(dev, "%s: IRQ=%u\n", __func__, irq);
631 
632 	return 0;
633 }
634 
635 static int moxart_remove(struct platform_device *pdev)
636 {
637 	struct moxart_dmadev *m = platform_get_drvdata(pdev);
638 
639 	devm_free_irq(&pdev->dev, m->irq, m);
640 
641 	dma_async_device_unregister(&m->dma_slave);
642 
643 	if (pdev->dev.of_node)
644 		of_dma_controller_free(pdev->dev.of_node);
645 
646 	return 0;
647 }
648 
649 static const struct of_device_id moxart_dma_match[] = {
650 	{ .compatible = "moxa,moxart-dma" },
651 	{ }
652 };
653 MODULE_DEVICE_TABLE(of, moxart_dma_match);
654 
655 static struct platform_driver moxart_driver = {
656 	.probe	= moxart_probe,
657 	.remove	= moxart_remove,
658 	.driver = {
659 		.name		= "moxart-dma-engine",
660 		.of_match_table	= moxart_dma_match,
661 	},
662 };
663 
664 static int moxart_init(void)
665 {
666 	return platform_driver_register(&moxart_driver);
667 }
668 subsys_initcall(moxart_init);
669 
670 static void __exit moxart_exit(void)
671 {
672 	platform_driver_unregister(&moxart_driver);
673 }
674 module_exit(moxart_exit);
675 
676 MODULE_AUTHOR("Jonas Jensen <jonas.jensen@gmail.com>");
677 MODULE_DESCRIPTION("MOXART DMA engine driver");
678 MODULE_LICENSE("GPL v2");
679