xref: /linux/drivers/spi/spi-dw-dma.c (revision dbcedec3a31119d7594baacc743300d127c99c56)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Special handling for DW DMA core
4  *
5  * Copyright (c) 2009, 2014 Intel Corporation.
6  */
7 
8 #include <linux/completion.h>
9 #include <linux/dma-mapping.h>
10 #include <linux/dmaengine.h>
11 #include <linux/irqreturn.h>
12 #include <linux/jiffies.h>
13 #include <linux/module.h>
14 #include <linux/pci.h>
15 #include <linux/platform_data/dma-dw.h>
16 #include <linux/spi/spi.h>
17 #include <linux/types.h>
18 
19 #include "spi-dw.h"
20 
21 #define DW_SPI_RX_BUSY		0
22 #define DW_SPI_RX_BURST_LEVEL	16
23 #define DW_SPI_TX_BUSY		1
24 #define DW_SPI_TX_BURST_LEVEL	16
25 
26 static bool dw_spi_dma_chan_filter(struct dma_chan *chan, void *param)
27 {
28 	struct dw_dma_slave *s = param;
29 
30 	if (s->dma_dev != chan->device->dev)
31 		return false;
32 
33 	chan->private = s;
34 	return true;
35 }
36 
37 static void dw_spi_dma_maxburst_init(struct dw_spi *dws)
38 {
39 	struct dma_slave_caps caps;
40 	u32 max_burst, def_burst;
41 	int ret;
42 
43 	def_burst = dws->fifo_len / 2;
44 
45 	ret = dma_get_slave_caps(dws->rxchan, &caps);
46 	if (!ret && caps.max_burst)
47 		max_burst = caps.max_burst;
48 	else
49 		max_burst = DW_SPI_RX_BURST_LEVEL;
50 
51 	dws->rxburst = min(max_burst, def_burst);
52 	dw_writel(dws, DW_SPI_DMARDLR, dws->rxburst - 1);
53 
54 	ret = dma_get_slave_caps(dws->txchan, &caps);
55 	if (!ret && caps.max_burst)
56 		max_burst = caps.max_burst;
57 	else
58 		max_burst = DW_SPI_TX_BURST_LEVEL;
59 
60 	/*
61 	 * Having a Rx DMA channel serviced with higher priority than a Tx DMA
62 	 * channel might not be enough to provide a well balanced DMA-based
63 	 * SPI transfer interface. There might still be moments when the Tx DMA
64 	 * channel is occasionally handled faster than the Rx DMA channel.
65 	 * That in its turn will eventually cause the SPI Rx FIFO overflow if
66 	 * SPI bus speed is high enough to fill the SPI Rx FIFO in before it's
67 	 * cleared by the Rx DMA channel. In order to fix the problem the Tx
68 	 * DMA activity is intentionally slowed down by limiting the SPI Tx
69 	 * FIFO depth with a value twice bigger than the Tx burst length.
70 	 */
71 	dws->txburst = min(max_burst, def_burst);
72 	dw_writel(dws, DW_SPI_DMATDLR, dws->txburst);
73 }
74 
75 static int dw_spi_dma_caps_init(struct dw_spi *dws)
76 {
77 	struct dma_slave_caps tx, rx;
78 	int ret;
79 
80 	ret = dma_get_slave_caps(dws->txchan, &tx);
81 	if (ret)
82 		return ret;
83 
84 	ret = dma_get_slave_caps(dws->rxchan, &rx);
85 	if (ret)
86 		return ret;
87 
88 	if (!(tx.directions & BIT(DMA_MEM_TO_DEV) &&
89 	      rx.directions & BIT(DMA_DEV_TO_MEM)))
90 		return -ENXIO;
91 
92 	if (tx.max_sg_burst > 0 && rx.max_sg_burst > 0)
93 		dws->dma_sg_burst = min(tx.max_sg_burst, rx.max_sg_burst);
94 	else if (tx.max_sg_burst > 0)
95 		dws->dma_sg_burst = tx.max_sg_burst;
96 	else if (rx.max_sg_burst > 0)
97 		dws->dma_sg_burst = rx.max_sg_burst;
98 	else
99 		dws->dma_sg_burst = 0;
100 
101 	/*
102 	 * Assuming both channels belong to the same DMA controller hence the
103 	 * peripheral side address width capabilities most likely would be
104 	 * the same.
105 	 */
106 	dws->dma_addr_widths = tx.dst_addr_widths & rx.src_addr_widths;
107 
108 	return 0;
109 }
110 
111 static int dw_spi_dma_init_mfld(struct device *dev, struct dw_spi *dws)
112 {
113 	struct dw_dma_slave dma_tx = { .dst_id = 1 }, *tx = &dma_tx;
114 	struct dw_dma_slave dma_rx = { .src_id = 0 }, *rx = &dma_rx;
115 	struct pci_dev *dma_dev;
116 	dma_cap_mask_t mask;
117 	int ret = -EBUSY;
118 
119 	/*
120 	 * Get pci device for DMA controller, currently it could only
121 	 * be the DMA controller of Medfield
122 	 */
123 	dma_dev = pci_get_device(PCI_VENDOR_ID_INTEL, 0x0827, NULL);
124 	if (!dma_dev)
125 		return -ENODEV;
126 
127 	dma_cap_zero(mask);
128 	dma_cap_set(DMA_SLAVE, mask);
129 
130 	/* 1. Init rx channel */
131 	rx->dma_dev = &dma_dev->dev;
132 	dws->rxchan = dma_request_channel(mask, dw_spi_dma_chan_filter, rx);
133 	if (!dws->rxchan)
134 		goto err_exit;
135 
136 	/* 2. Init tx channel */
137 	tx->dma_dev = &dma_dev->dev;
138 	dws->txchan = dma_request_channel(mask, dw_spi_dma_chan_filter, tx);
139 	if (!dws->txchan)
140 		goto free_rxchan;
141 
142 	dws->host->dma_rx = dws->rxchan;
143 	dws->host->dma_tx = dws->txchan;
144 
145 	init_completion(&dws->dma_completion);
146 
147 	ret = dw_spi_dma_caps_init(dws);
148 	if (ret)
149 		goto free_txchan;
150 
151 	dw_spi_dma_maxburst_init(dws);
152 
153 	pci_dev_put(dma_dev);
154 
155 	return 0;
156 
157 free_txchan:
158 	dma_release_channel(dws->txchan);
159 	dws->txchan = NULL;
160 free_rxchan:
161 	dma_release_channel(dws->rxchan);
162 	dws->rxchan = NULL;
163 err_exit:
164 	pci_dev_put(dma_dev);
165 	return ret;
166 }
167 
168 static int dw_spi_dma_init_generic(struct device *dev, struct dw_spi *dws)
169 {
170 	int ret;
171 
172 	dws->rxchan = dma_request_chan(dev, "rx");
173 	if (IS_ERR(dws->rxchan)) {
174 		ret = PTR_ERR(dws->rxchan);
175 		dws->rxchan = NULL;
176 		goto err_exit;
177 	}
178 
179 	dws->txchan = dma_request_chan(dev, "tx");
180 	if (IS_ERR(dws->txchan)) {
181 		ret = PTR_ERR(dws->txchan);
182 		dws->txchan = NULL;
183 		goto free_rxchan;
184 	}
185 
186 	dws->host->dma_rx = dws->rxchan;
187 	dws->host->dma_tx = dws->txchan;
188 
189 	init_completion(&dws->dma_completion);
190 
191 	ret = dw_spi_dma_caps_init(dws);
192 	if (ret)
193 		goto free_txchan;
194 
195 	dw_spi_dma_maxburst_init(dws);
196 
197 	return 0;
198 
199 free_txchan:
200 	dma_release_channel(dws->txchan);
201 	dws->txchan = NULL;
202 free_rxchan:
203 	dma_release_channel(dws->rxchan);
204 	dws->rxchan = NULL;
205 err_exit:
206 	return ret;
207 }
208 
209 static void dw_spi_dma_exit(struct dw_spi *dws)
210 {
211 	if (dws->txchan) {
212 		dmaengine_terminate_sync(dws->txchan);
213 		dma_release_channel(dws->txchan);
214 	}
215 
216 	if (dws->rxchan) {
217 		dmaengine_terminate_sync(dws->rxchan);
218 		dma_release_channel(dws->rxchan);
219 	}
220 }
221 
222 static irqreturn_t dw_spi_dma_transfer_handler(struct dw_spi *dws)
223 {
224 	dw_spi_check_status(dws, false);
225 
226 	complete(&dws->dma_completion);
227 
228 	return IRQ_HANDLED;
229 }
230 
231 static enum dma_slave_buswidth dw_spi_dma_convert_width(u8 n_bytes)
232 {
233 	switch (n_bytes) {
234 	case 1:
235 		return DMA_SLAVE_BUSWIDTH_1_BYTE;
236 	case 2:
237 		return DMA_SLAVE_BUSWIDTH_2_BYTES;
238 	case 4:
239 		return DMA_SLAVE_BUSWIDTH_4_BYTES;
240 	default:
241 		return DMA_SLAVE_BUSWIDTH_UNDEFINED;
242 	}
243 }
244 
245 static bool dw_spi_can_dma(struct spi_controller *host,
246 			   struct spi_device *spi, struct spi_transfer *xfer)
247 {
248 	struct dw_spi *dws = spi_controller_get_devdata(host);
249 	enum dma_slave_buswidth dma_bus_width;
250 
251 	if (xfer->len <= dws->fifo_len)
252 		return false;
253 
254 	dma_bus_width = dw_spi_dma_convert_width(dws->n_bytes);
255 
256 	return dws->dma_addr_widths & BIT(dma_bus_width);
257 }
258 
259 static int dw_spi_dma_wait(struct dw_spi *dws, unsigned int len, u32 speed)
260 {
261 	unsigned long long ms;
262 
263 	ms = len * MSEC_PER_SEC * BITS_PER_BYTE;
264 	do_div(ms, speed);
265 	ms += ms + 200;
266 
267 	if (ms > UINT_MAX)
268 		ms = UINT_MAX;
269 
270 	ms = wait_for_completion_timeout(&dws->dma_completion,
271 					 msecs_to_jiffies(ms));
272 
273 	if (ms == 0) {
274 		dev_err(&dws->host->cur_msg->spi->dev,
275 			"DMA transaction timed out\n");
276 		return -ETIMEDOUT;
277 	}
278 
279 	return 0;
280 }
281 
282 static inline bool dw_spi_dma_tx_busy(struct dw_spi *dws)
283 {
284 	return !(dw_readl(dws, DW_SPI_SR) & DW_SPI_SR_TF_EMPT);
285 }
286 
287 static int dw_spi_dma_wait_tx_done(struct dw_spi *dws,
288 				   struct spi_transfer *xfer)
289 {
290 	int retry = DW_SPI_WAIT_RETRIES;
291 	struct spi_delay delay;
292 	u32 nents;
293 
294 	nents = dw_readl(dws, DW_SPI_TXFLR);
295 	delay.unit = SPI_DELAY_UNIT_SCK;
296 	delay.value = nents * dws->n_bytes * BITS_PER_BYTE;
297 
298 	while (dw_spi_dma_tx_busy(dws) && retry--)
299 		spi_delay_exec(&delay, xfer);
300 
301 	if (retry < 0) {
302 		dev_err(&dws->host->dev, "Tx hanged up\n");
303 		return -EIO;
304 	}
305 
306 	return 0;
307 }
308 
309 /*
310  * dws->dma_chan_busy is set before the dma transfer starts, callback for tx
311  * channel will clear a corresponding bit.
312  */
313 static void dw_spi_dma_tx_done(void *arg)
314 {
315 	struct dw_spi *dws = arg;
316 
317 	clear_bit(DW_SPI_TX_BUSY, &dws->dma_chan_busy);
318 	if (test_bit(DW_SPI_RX_BUSY, &dws->dma_chan_busy))
319 		return;
320 
321 	complete(&dws->dma_completion);
322 }
323 
324 static int dw_spi_dma_config_tx(struct dw_spi *dws)
325 {
326 	struct dma_slave_config txconf;
327 
328 	memset(&txconf, 0, sizeof(txconf));
329 	txconf.direction = DMA_MEM_TO_DEV;
330 	txconf.dst_addr = dws->dma_addr;
331 	txconf.dst_maxburst = dws->txburst;
332 	txconf.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
333 	txconf.dst_addr_width = dw_spi_dma_convert_width(dws->n_bytes);
334 	txconf.device_fc = false;
335 
336 	return dmaengine_slave_config(dws->txchan, &txconf);
337 }
338 
339 static int dw_spi_dma_submit_tx(struct dw_spi *dws, struct scatterlist *sgl,
340 				unsigned int nents)
341 {
342 	struct dma_async_tx_descriptor *txdesc;
343 	dma_cookie_t cookie;
344 	int ret;
345 
346 	txdesc = dmaengine_prep_slave_sg(dws->txchan, sgl, nents,
347 					 DMA_MEM_TO_DEV,
348 					 DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
349 	if (!txdesc)
350 		return -ENOMEM;
351 
352 	txdesc->callback = dw_spi_dma_tx_done;
353 	txdesc->callback_param = dws;
354 
355 	cookie = dmaengine_submit(txdesc);
356 	ret = dma_submit_error(cookie);
357 	if (ret) {
358 		dmaengine_terminate_sync(dws->txchan);
359 		return ret;
360 	}
361 
362 	set_bit(DW_SPI_TX_BUSY, &dws->dma_chan_busy);
363 
364 	return 0;
365 }
366 
367 static inline bool dw_spi_dma_rx_busy(struct dw_spi *dws)
368 {
369 	return !!(dw_readl(dws, DW_SPI_SR) & DW_SPI_SR_RF_NOT_EMPT);
370 }
371 
372 static int dw_spi_dma_wait_rx_done(struct dw_spi *dws)
373 {
374 	int retry = DW_SPI_WAIT_RETRIES;
375 	struct spi_delay delay;
376 	unsigned long ns, us;
377 	u32 nents;
378 
379 	/*
380 	 * It's unlikely that DMA engine is still doing the data fetching, but
381 	 * if it's let's give it some reasonable time. The timeout calculation
382 	 * is based on the synchronous APB/SSI reference clock rate, on a
383 	 * number of data entries left in the Rx FIFO, times a number of clock
384 	 * periods normally needed for a single APB read/write transaction
385 	 * without PREADY signal utilized (which is true for the DW APB SSI
386 	 * controller).
387 	 */
388 	nents = dw_readl(dws, DW_SPI_RXFLR);
389 	ns = 4U * NSEC_PER_SEC / dws->max_freq * nents;
390 	if (ns <= NSEC_PER_USEC) {
391 		delay.unit = SPI_DELAY_UNIT_NSECS;
392 		delay.value = ns;
393 	} else {
394 		us = DIV_ROUND_UP(ns, NSEC_PER_USEC);
395 		delay.unit = SPI_DELAY_UNIT_USECS;
396 		delay.value = clamp_val(us, 0, USHRT_MAX);
397 	}
398 
399 	while (dw_spi_dma_rx_busy(dws) && retry--)
400 		spi_delay_exec(&delay, NULL);
401 
402 	if (retry < 0) {
403 		dev_err(&dws->host->dev, "Rx hanged up\n");
404 		return -EIO;
405 	}
406 
407 	return 0;
408 }
409 
410 /*
411  * dws->dma_chan_busy is set before the dma transfer starts, callback for rx
412  * channel will clear a corresponding bit.
413  */
414 static void dw_spi_dma_rx_done(void *arg)
415 {
416 	struct dw_spi *dws = arg;
417 
418 	clear_bit(DW_SPI_RX_BUSY, &dws->dma_chan_busy);
419 	if (test_bit(DW_SPI_TX_BUSY, &dws->dma_chan_busy))
420 		return;
421 
422 	complete(&dws->dma_completion);
423 }
424 
425 static int dw_spi_dma_config_rx(struct dw_spi *dws)
426 {
427 	struct dma_slave_config rxconf;
428 
429 	memset(&rxconf, 0, sizeof(rxconf));
430 	rxconf.direction = DMA_DEV_TO_MEM;
431 	rxconf.src_addr = dws->dma_addr;
432 	rxconf.src_maxburst = dws->rxburst;
433 	rxconf.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
434 	rxconf.src_addr_width = dw_spi_dma_convert_width(dws->n_bytes);
435 	rxconf.device_fc = false;
436 
437 	return dmaengine_slave_config(dws->rxchan, &rxconf);
438 }
439 
440 static int dw_spi_dma_submit_rx(struct dw_spi *dws, struct scatterlist *sgl,
441 				unsigned int nents)
442 {
443 	struct dma_async_tx_descriptor *rxdesc;
444 	dma_cookie_t cookie;
445 	int ret;
446 
447 	rxdesc = dmaengine_prep_slave_sg(dws->rxchan, sgl, nents,
448 					 DMA_DEV_TO_MEM,
449 					 DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
450 	if (!rxdesc)
451 		return -ENOMEM;
452 
453 	rxdesc->callback = dw_spi_dma_rx_done;
454 	rxdesc->callback_param = dws;
455 
456 	cookie = dmaengine_submit(rxdesc);
457 	ret = dma_submit_error(cookie);
458 	if (ret) {
459 		dmaengine_terminate_sync(dws->rxchan);
460 		return ret;
461 	}
462 
463 	set_bit(DW_SPI_RX_BUSY, &dws->dma_chan_busy);
464 
465 	return 0;
466 }
467 
468 static int dw_spi_dma_setup(struct dw_spi *dws, struct spi_transfer *xfer)
469 {
470 	u16 imr, dma_ctrl;
471 	int ret;
472 
473 	if (!xfer->tx_buf)
474 		return -EINVAL;
475 
476 	/* Setup DMA channels */
477 	ret = dw_spi_dma_config_tx(dws);
478 	if (ret)
479 		return ret;
480 
481 	if (xfer->rx_buf) {
482 		ret = dw_spi_dma_config_rx(dws);
483 		if (ret)
484 			return ret;
485 	}
486 
487 	/* Set the DMA handshaking interface */
488 	dma_ctrl = DW_SPI_DMACR_TDMAE;
489 	if (xfer->rx_buf)
490 		dma_ctrl |= DW_SPI_DMACR_RDMAE;
491 	dw_writel(dws, DW_SPI_DMACR, dma_ctrl);
492 
493 	/* Set the interrupt mask */
494 	imr = DW_SPI_INT_TXOI;
495 	if (xfer->rx_buf)
496 		imr |= DW_SPI_INT_RXUI | DW_SPI_INT_RXOI;
497 	dw_spi_umask_intr(dws, imr);
498 
499 	reinit_completion(&dws->dma_completion);
500 
501 	dws->transfer_handler = dw_spi_dma_transfer_handler;
502 
503 	return 0;
504 }
505 
506 static int dw_spi_dma_transfer_all(struct dw_spi *dws,
507 				   struct spi_transfer *xfer)
508 {
509 	int ret;
510 
511 	/* Submit the DMA Tx transfer */
512 	ret = dw_spi_dma_submit_tx(dws, xfer->tx_sg.sgl, xfer->tx_sg.nents);
513 	if (ret)
514 		goto err_clear_dmac;
515 
516 	/* Submit the DMA Rx transfer if required */
517 	if (xfer->rx_buf) {
518 		ret = dw_spi_dma_submit_rx(dws, xfer->rx_sg.sgl,
519 					   xfer->rx_sg.nents);
520 		if (ret)
521 			goto err_clear_dmac;
522 
523 		/* rx must be started before tx due to spi instinct */
524 		dma_async_issue_pending(dws->rxchan);
525 	}
526 
527 	dma_async_issue_pending(dws->txchan);
528 
529 	ret = dw_spi_dma_wait(dws, xfer->len, xfer->effective_speed_hz);
530 
531 err_clear_dmac:
532 	dw_writel(dws, DW_SPI_DMACR, 0);
533 
534 	return ret;
535 }
536 
537 /*
538  * In case if at least one of the requested DMA channels doesn't support the
539  * hardware accelerated SG list entries traverse, the DMA driver will most
540  * likely work that around by performing the IRQ-based SG list entries
541  * resubmission. That might and will cause a problem if the DMA Tx channel is
542  * recharged and re-executed before the Rx DMA channel. Due to
543  * non-deterministic IRQ-handler execution latency the DMA Tx channel will
544  * start pushing data to the SPI bus before the Rx DMA channel is even
545  * reinitialized with the next inbound SG list entry. By doing so the DMA Tx
546  * channel will implicitly start filling the DW APB SSI Rx FIFO up, which while
547  * the DMA Rx channel being recharged and re-executed will eventually be
548  * overflown.
549  *
550  * In order to solve the problem we have to feed the DMA engine with SG list
551  * entries one-by-one. It shall keep the DW APB SSI Tx and Rx FIFOs
552  * synchronized and prevent the Rx FIFO overflow. Since in general the tx_sg
553  * and rx_sg lists may have different number of entries of different lengths
554  * (though total length should match) let's virtually split the SG-lists to the
555  * set of DMA transfers, which length is a minimum of the ordered SG-entries
556  * lengths. An ASCII-sketch of the implemented algo is following:
557  *                  xfer->len
558  *                |___________|
559  * tx_sg list:    |___|____|__|
560  * rx_sg list:    |_|____|____|
561  * DMA transfers: |_|_|__|_|__|
562  *
563  * Note in order to have this workaround solving the denoted problem the DMA
564  * engine driver should properly initialize the max_sg_burst capability and set
565  * the DMA device max segment size parameter with maximum data block size the
566  * DMA engine supports.
567  */
568 
569 static int dw_spi_dma_transfer_one(struct dw_spi *dws,
570 				   struct spi_transfer *xfer)
571 {
572 	struct scatterlist *tx_sg = NULL, *rx_sg = NULL, tx_tmp, rx_tmp;
573 	unsigned int tx_len = 0, rx_len = 0;
574 	unsigned int base, len;
575 	int ret;
576 
577 	sg_init_table(&tx_tmp, 1);
578 	sg_init_table(&rx_tmp, 1);
579 
580 	for (base = 0; base < xfer->len; base += len) {
581 		/* Fetch next Tx DMA data chunk */
582 		if (!tx_len) {
583 			tx_sg = !tx_sg ? &xfer->tx_sg.sgl[0] : sg_next(tx_sg);
584 			sg_dma_address(&tx_tmp) = sg_dma_address(tx_sg);
585 			tx_len = sg_dma_len(tx_sg);
586 		}
587 
588 		/* Fetch next Rx DMA data chunk */
589 		if (!rx_len) {
590 			rx_sg = !rx_sg ? &xfer->rx_sg.sgl[0] : sg_next(rx_sg);
591 			sg_dma_address(&rx_tmp) = sg_dma_address(rx_sg);
592 			rx_len = sg_dma_len(rx_sg);
593 		}
594 
595 		len = min(tx_len, rx_len);
596 
597 		sg_dma_len(&tx_tmp) = len;
598 		sg_dma_len(&rx_tmp) = len;
599 
600 		/* Submit DMA Tx transfer */
601 		ret = dw_spi_dma_submit_tx(dws, &tx_tmp, 1);
602 		if (ret)
603 			break;
604 
605 		/* Submit DMA Rx transfer */
606 		ret = dw_spi_dma_submit_rx(dws, &rx_tmp, 1);
607 		if (ret)
608 			break;
609 
610 		/* Rx must be started before Tx due to SPI instinct */
611 		dma_async_issue_pending(dws->rxchan);
612 
613 		dma_async_issue_pending(dws->txchan);
614 
615 		/*
616 		 * Here we only need to wait for the DMA transfer to be
617 		 * finished since SPI controller is kept enabled during the
618 		 * procedure this loop implements and there is no risk to lose
619 		 * data left in the Tx/Rx FIFOs.
620 		 */
621 		ret = dw_spi_dma_wait(dws, len, xfer->effective_speed_hz);
622 		if (ret)
623 			break;
624 
625 		reinit_completion(&dws->dma_completion);
626 
627 		sg_dma_address(&tx_tmp) += len;
628 		sg_dma_address(&rx_tmp) += len;
629 		tx_len -= len;
630 		rx_len -= len;
631 	}
632 
633 	dw_writel(dws, DW_SPI_DMACR, 0);
634 
635 	return ret;
636 }
637 
638 static int dw_spi_dma_transfer(struct dw_spi *dws, struct spi_transfer *xfer)
639 {
640 	unsigned int nents;
641 	int ret;
642 
643 	nents = max(xfer->tx_sg.nents, xfer->rx_sg.nents);
644 
645 	/*
646 	 * Execute normal DMA-based transfer (which submits the Rx and Tx SG
647 	 * lists directly to the DMA engine at once) if either full hardware
648 	 * accelerated SG list traverse is supported by both channels, or the
649 	 * Tx-only SPI transfer is requested, or the DMA engine is capable to
650 	 * handle both SG lists on hardware accelerated basis.
651 	 */
652 	if (!dws->dma_sg_burst || !xfer->rx_buf || nents <= dws->dma_sg_burst)
653 		ret = dw_spi_dma_transfer_all(dws, xfer);
654 	else
655 		ret = dw_spi_dma_transfer_one(dws, xfer);
656 	if (ret)
657 		return ret;
658 
659 	if (dws->host->cur_msg->status == -EINPROGRESS) {
660 		ret = dw_spi_dma_wait_tx_done(dws, xfer);
661 		if (ret)
662 			return ret;
663 	}
664 
665 	if (xfer->rx_buf && dws->host->cur_msg->status == -EINPROGRESS)
666 		ret = dw_spi_dma_wait_rx_done(dws);
667 
668 	return ret;
669 }
670 
671 static void dw_spi_dma_stop(struct dw_spi *dws)
672 {
673 	if (test_bit(DW_SPI_TX_BUSY, &dws->dma_chan_busy)) {
674 		dmaengine_terminate_sync(dws->txchan);
675 		clear_bit(DW_SPI_TX_BUSY, &dws->dma_chan_busy);
676 	}
677 	if (test_bit(DW_SPI_RX_BUSY, &dws->dma_chan_busy)) {
678 		dmaengine_terminate_sync(dws->rxchan);
679 		clear_bit(DW_SPI_RX_BUSY, &dws->dma_chan_busy);
680 	}
681 }
682 
683 static const struct dw_spi_dma_ops dw_spi_dma_mfld_ops = {
684 	.dma_init	= dw_spi_dma_init_mfld,
685 	.dma_exit	= dw_spi_dma_exit,
686 	.dma_setup	= dw_spi_dma_setup,
687 	.can_dma	= dw_spi_can_dma,
688 	.dma_transfer	= dw_spi_dma_transfer,
689 	.dma_stop	= dw_spi_dma_stop,
690 };
691 
692 void dw_spi_dma_setup_mfld(struct dw_spi *dws)
693 {
694 	dws->dma_ops = &dw_spi_dma_mfld_ops;
695 }
696 EXPORT_SYMBOL_NS_GPL(dw_spi_dma_setup_mfld, SPI_DW_CORE);
697 
698 static const struct dw_spi_dma_ops dw_spi_dma_generic_ops = {
699 	.dma_init	= dw_spi_dma_init_generic,
700 	.dma_exit	= dw_spi_dma_exit,
701 	.dma_setup	= dw_spi_dma_setup,
702 	.can_dma	= dw_spi_can_dma,
703 	.dma_transfer	= dw_spi_dma_transfer,
704 	.dma_stop	= dw_spi_dma_stop,
705 };
706 
707 void dw_spi_dma_setup_generic(struct dw_spi *dws)
708 {
709 	dws->dma_ops = &dw_spi_dma_generic_ops;
710 }
711 EXPORT_SYMBOL_NS_GPL(dw_spi_dma_setup_generic, SPI_DW_CORE);
712