summaryrefslogtreecommitdiff
path: root/drivers/spi/spi-rockchip.c
blob: 3912526ead6641067e189a825c9df8ebf8faabfc (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
/*
 * Copyright (c) 2014, Fuzhou Rockchip Electronics Co., Ltd
 * Author: Addy Ke <addy.ke@rock-chips.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 */

#include <linux/clk.h>
#include <linux/dmaengine.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/pinctrl/consumer.h>
#include <linux/platform_device.h>
#include <linux/spi/spi.h>
#include <linux/pm_runtime.h>
#include <linux/scatterlist.h>

#define DRIVER_NAME "rockchip-spi"

#define ROCKCHIP_SPI_CLR_BITS(reg, bits) \
		writel_relaxed(readl_relaxed(reg) & ~(bits), reg)
#define ROCKCHIP_SPI_SET_BITS(reg, bits) \
		writel_relaxed(readl_relaxed(reg) | (bits), reg)

/* SPI register offsets */
#define ROCKCHIP_SPI_CTRLR0			0x0000
#define ROCKCHIP_SPI_CTRLR1			0x0004
#define ROCKCHIP_SPI_SSIENR			0x0008
#define ROCKCHIP_SPI_SER			0x000c
#define ROCKCHIP_SPI_BAUDR			0x0010
#define ROCKCHIP_SPI_TXFTLR			0x0014
#define ROCKCHIP_SPI_RXFTLR			0x0018
#define ROCKCHIP_SPI_TXFLR			0x001c
#define ROCKCHIP_SPI_RXFLR			0x0020
#define ROCKCHIP_SPI_SR				0x0024
#define ROCKCHIP_SPI_IPR			0x0028
#define ROCKCHIP_SPI_IMR			0x002c
#define ROCKCHIP_SPI_ISR			0x0030
#define ROCKCHIP_SPI_RISR			0x0034
#define ROCKCHIP_SPI_ICR			0x0038
#define ROCKCHIP_SPI_DMACR			0x003c
#define ROCKCHIP_SPI_DMATDLR		0x0040
#define ROCKCHIP_SPI_DMARDLR		0x0044
#define ROCKCHIP_SPI_TXDR			0x0400
#define ROCKCHIP_SPI_RXDR			0x0800

/* Bit fields in CTRLR0 */
#define CR0_DFS_OFFSET				0
#define CR0_DFS_4BIT				0x0
#define CR0_DFS_8BIT				0x1
#define CR0_DFS_16BIT				0x2

#define CR0_CFS_OFFSET				2

#define CR0_SCPH_OFFSET				6

#define CR0_SCPOL_OFFSET			7

#define CR0_CSM_OFFSET				8
#define CR0_CSM_KEEP				0x0
/* ss_n be high for half sclk_out cycles */
#define CR0_CSM_HALF				0X1
/* ss_n be high for one sclk_out cycle */
#define CR0_CSM_ONE					0x2

/* ss_n to sclk_out delay */
#define CR0_SSD_OFFSET				10
/*
 * The period between ss_n active and
 * sclk_out active is half sclk_out cycles
 */
#define CR0_SSD_HALF				0x0
/*
 * The period between ss_n active and
 * sclk_out active is one sclk_out cycle
 */
#define CR0_SSD_ONE					0x1

#define CR0_EM_OFFSET				11
#define CR0_EM_LITTLE				0x0
#define CR0_EM_BIG					0x1

#define CR0_FBM_OFFSET				12
#define CR0_FBM_MSB					0x0
#define CR0_FBM_LSB					0x1

#define CR0_BHT_OFFSET				13
#define CR0_BHT_16BIT				0x0
#define CR0_BHT_8BIT				0x1

#define CR0_RSD_OFFSET				14
#define CR0_RSD_MAX				0x3

#define CR0_FRF_OFFSET				16
#define CR0_FRF_SPI					0x0
#define CR0_FRF_SSP					0x1
#define CR0_FRF_MICROWIRE			0x2

#define CR0_XFM_OFFSET				18
#define CR0_XFM_MASK				(0x03 << SPI_XFM_OFFSET)
#define CR0_XFM_TR					0x0
#define CR0_XFM_TO					0x1
#define CR0_XFM_RO					0x2

#define CR0_OPM_OFFSET				20
#define CR0_OPM_MASTER				0x0
#define CR0_OPM_SLAVE				0x1

#define CR0_MTM_OFFSET				0x21

/* Bit fields in SER, 2bit */
#define SER_MASK					0x3

/* Bit fields in BAUDR */
#define BAUDR_SCKDV_MIN				2
#define BAUDR_SCKDV_MAX				65534

/* Bit fields in SR, 5bit */
#define SR_MASK						0x1f
#define SR_BUSY						(1 << 0)
#define SR_TF_FULL					(1 << 1)
#define SR_TF_EMPTY					(1 << 2)
#define SR_RF_EMPTY					(1 << 3)
#define SR_RF_FULL					(1 << 4)

/* Bit fields in ISR, IMR, ISR, RISR, 5bit */
#define INT_MASK					0x1f
#define INT_TF_EMPTY				(1 << 0)
#define INT_TF_OVERFLOW				(1 << 1)
#define INT_RF_UNDERFLOW			(1 << 2)
#define INT_RF_OVERFLOW				(1 << 3)
#define INT_RF_FULL					(1 << 4)

/* Bit fields in ICR, 4bit */
#define ICR_MASK					0x0f
#define ICR_ALL						(1 << 0)
#define ICR_RF_UNDERFLOW			(1 << 1)
#define ICR_RF_OVERFLOW				(1 << 2)
#define ICR_TF_OVERFLOW				(1 << 3)

/* Bit fields in DMACR */
#define RF_DMA_EN					(1 << 0)
#define TF_DMA_EN					(1 << 1)

/* Driver state flags */
#define RXDMA					(1 << 0)
#define TXDMA					(1 << 1)

/* sclk_out: spi master internal logic in rk3x can support 50Mhz */
#define MAX_SCLK_OUT				50000000U

/*
 * SPI_CTRLR1 is 16-bits, so we should support lengths of 0xffff + 1. However,
 * the controller seems to hang when given 0x10000, so stick with this for now.
 */
#define ROCKCHIP_SPI_MAX_TRANLEN		0xffff

#define ROCKCHIP_SPI_MAX_CS_NUM			2

struct rockchip_spi {
	struct device *dev;

	struct clk *spiclk;
	struct clk *apb_pclk;

	void __iomem *regs;
	dma_addr_t dma_addr_rx;
	dma_addr_t dma_addr_tx;

	const void *tx;
	void *rx;
	unsigned int tx_left;
	unsigned int rx_left;

	atomic_t state;

	/*depth of the FIFO buffer */
	u32 fifo_len;
	/* frequency of spiclk */
	u32 freq;

	u8 n_bytes;
	u8 rsd;

	bool cs_asserted[ROCKCHIP_SPI_MAX_CS_NUM];
};

static inline void spi_enable_chip(struct rockchip_spi *rs, bool enable)
{
	writel_relaxed((enable ? 1U : 0U), rs->regs + ROCKCHIP_SPI_SSIENR);
}

static inline void wait_for_idle(struct rockchip_spi *rs)
{
	unsigned long timeout = jiffies + msecs_to_jiffies(5);

	do {
		if (!(readl_relaxed(rs->regs + ROCKCHIP_SPI_SR) & SR_BUSY))
			return;
	} while (!time_after(jiffies, timeout));

	dev_warn(rs->dev, "spi controller is in busy state!\n");
}

static u32 get_fifo_len(struct rockchip_spi *rs)
{
	u32 fifo;

	for (fifo = 2; fifo < 32; fifo++) {
		writel_relaxed(fifo, rs->regs + ROCKCHIP_SPI_TXFTLR);
		if (fifo != readl_relaxed(rs->regs + ROCKCHIP_SPI_TXFTLR))
			break;
	}

	writel_relaxed(0, rs->regs + ROCKCHIP_SPI_TXFTLR);

	return (fifo == 31) ? 0 : fifo;
}

static void rockchip_spi_set_cs(struct spi_device *spi, bool enable)
{
	struct spi_master *master = spi->master;
	struct rockchip_spi *rs = spi_master_get_devdata(master);
	bool cs_asserted = !enable;

	/* Return immediately for no-op */
	if (cs_asserted == rs->cs_asserted[spi->chip_select])
		return;

	if (cs_asserted) {
		/* Keep things powered as long as CS is asserted */
		pm_runtime_get_sync(rs->dev);

		ROCKCHIP_SPI_SET_BITS(rs->regs + ROCKCHIP_SPI_SER,
				      BIT(spi->chip_select));
	} else {
		ROCKCHIP_SPI_CLR_BITS(rs->regs + ROCKCHIP_SPI_SER,
				      BIT(spi->chip_select));

		/* Drop reference from when we first asserted CS */
		pm_runtime_put(rs->dev);
	}

	rs->cs_asserted[spi->chip_select] = cs_asserted;
}

static void rockchip_spi_handle_err(struct spi_master *master,
				    struct spi_message *msg)
{
	struct rockchip_spi *rs = spi_master_get_devdata(master);

	/* stop running spi transfer
	 * this also flushes both rx and tx fifos
	 */
	spi_enable_chip(rs, false);

	/* make sure all interrupts are masked */
	writel_relaxed(0, rs->regs + ROCKCHIP_SPI_IMR);

	if (atomic_read(&rs->state) & TXDMA)
		dmaengine_terminate_async(master->dma_tx);

	if (atomic_read(&rs->state) & RXDMA)
		dmaengine_terminate_async(master->dma_rx);
}

static void rockchip_spi_pio_writer(struct rockchip_spi *rs)
{
	u32 tx_free = rs->fifo_len - readl_relaxed(rs->regs + ROCKCHIP_SPI_TXFLR);
	u32 words = min(rs->tx_left, tx_free);

	rs->tx_left -= words;
	for (; words; words--) {
		u32 txw;

		if (rs->n_bytes == 1)
			txw = *(u8 *)rs->tx;
		else
			txw = *(u16 *)rs->tx;

		writel_relaxed(txw, rs->regs + ROCKCHIP_SPI_TXDR);
		rs->tx += rs->n_bytes;
	}
}

static void rockchip_spi_pio_reader(struct rockchip_spi *rs)
{
	u32 words = readl_relaxed(rs->regs + ROCKCHIP_SPI_RXFLR);
	u32 rx_left = rs->rx_left - words;

	/* the hardware doesn't allow us to change fifo threshold
	 * level while spi is enabled, so instead make sure to leave
	 * enough words in the rx fifo to get the last interrupt
	 * exactly when all words have been received
	 */
	if (rx_left) {
		u32 ftl = readl_relaxed(rs->regs + ROCKCHIP_SPI_RXFTLR) + 1;

		if (rx_left < ftl) {
			rx_left = ftl;
			words = rs->rx_left - rx_left;
		}
	}

	rs->rx_left = rx_left;
	for (; words; words--) {
		u32 rxw = readl_relaxed(rs->regs + ROCKCHIP_SPI_RXDR);

		if (!rs->rx)
			continue;

		if (rs->n_bytes == 1)
			*(u8 *)rs->rx = (u8)rxw;
		else
			*(u16 *)rs->rx = (u16)rxw;
		rs->rx += rs->n_bytes;
	}
}

static irqreturn_t rockchip_spi_isr(int irq, void *dev_id)
{
	struct spi_master *master = dev_id;
	struct rockchip_spi *rs = spi_master_get_devdata(master);

	if (rs->tx_left)
		rockchip_spi_pio_writer(rs);

	rockchip_spi_pio_reader(rs);
	if (!rs->rx_left) {
		spi_enable_chip(rs, false);
		writel_relaxed(0, rs->regs + ROCKCHIP_SPI_IMR);
		spi_finalize_current_transfer(master);
	}

	return IRQ_HANDLED;
}

static int rockchip_spi_prepare_irq(struct rockchip_spi *rs,
		struct spi_transfer *xfer)
{
	rs->tx = xfer->tx_buf;
	rs->rx = xfer->rx_buf;
	rs->tx_left = rs->tx ? xfer->len / rs->n_bytes : 0;
	rs->rx_left = xfer->len / rs->n_bytes;

	writel_relaxed(INT_RF_FULL, rs->regs + ROCKCHIP_SPI_IMR);
	spi_enable_chip(rs, true);

	if (rs->tx_left)
		rockchip_spi_pio_writer(rs);

	/* 1 means the transfer is in progress */
	return 1;
}

static void rockchip_spi_dma_rxcb(void *data)
{
	struct spi_master *master = data;
	struct rockchip_spi *rs = spi_master_get_devdata(master);
	int state = atomic_fetch_andnot(RXDMA, &rs->state);

	if (state & TXDMA)
		return;

	spi_enable_chip(rs, false);
	spi_finalize_current_transfer(master);
}

static void rockchip_spi_dma_txcb(void *data)
{
	struct spi_master *master = data;
	struct rockchip_spi *rs = spi_master_get_devdata(master);
	int state = atomic_fetch_andnot(TXDMA, &rs->state);

	if (state & RXDMA)
		return;

	/* Wait until the FIFO data completely. */
	wait_for_idle(rs);

	spi_enable_chip(rs, false);
	spi_finalize_current_transfer(master);
}

static int rockchip_spi_prepare_dma(struct rockchip_spi *rs,
		struct spi_master *master, struct spi_transfer *xfer)
{
	struct dma_async_tx_descriptor *rxdesc, *txdesc;

	atomic_set(&rs->state, 0);

	rxdesc = NULL;
	if (xfer->rx_buf) {
		struct dma_slave_config rxconf = {
			.direction = DMA_DEV_TO_MEM,
			.src_addr = rs->dma_addr_rx,
			.src_addr_width = rs->n_bytes,
			.src_maxburst = 1,
		};

		dmaengine_slave_config(master->dma_rx, &rxconf);

		rxdesc = dmaengine_prep_slave_sg(
				master->dma_rx,
				xfer->rx_sg.sgl, xfer->rx_sg.nents,
				DMA_DEV_TO_MEM, DMA_PREP_INTERRUPT);
		if (!rxdesc)
			return -EINVAL;

		rxdesc->callback = rockchip_spi_dma_rxcb;
		rxdesc->callback_param = master;
	}

	txdesc = NULL;
	if (xfer->tx_buf) {
		struct dma_slave_config txconf = {
			.direction = DMA_MEM_TO_DEV,
			.dst_addr = rs->dma_addr_tx,
			.dst_addr_width = rs->n_bytes,
			.dst_maxburst = rs->fifo_len / 2,
		};

		dmaengine_slave_config(master->dma_tx, &txconf);

		txdesc = dmaengine_prep_slave_sg(
				master->dma_tx,
				xfer->tx_sg.sgl, xfer->tx_sg.nents,
				DMA_MEM_TO_DEV, DMA_PREP_INTERRUPT);
		if (!txdesc) {
			if (rxdesc)
				dmaengine_terminate_sync(master->dma_rx);
			return -EINVAL;
		}

		txdesc->callback = rockchip_spi_dma_txcb;
		txdesc->callback_param = master;
	}

	/* rx must be started before tx due to spi instinct */
	if (rxdesc) {
		atomic_or(RXDMA, &rs->state);
		dmaengine_submit(rxdesc);
		dma_async_issue_pending(master->dma_rx);
	}

	spi_enable_chip(rs, true);

	if (txdesc) {
		atomic_or(TXDMA, &rs->state);
		dmaengine_submit(txdesc);
		dma_async_issue_pending(master->dma_tx);
	}

	/* 1 means the transfer is in progress */
	return 1;
}

static void rockchip_spi_config(struct rockchip_spi *rs,
		struct spi_device *spi, struct spi_transfer *xfer,
		bool use_dma)
{
	u32 cr0 = CR0_FRF_SPI  << CR0_FRF_OFFSET
	        | CR0_BHT_8BIT << CR0_BHT_OFFSET
	        | CR0_SSD_ONE  << CR0_SSD_OFFSET
	        | CR0_EM_BIG   << CR0_EM_OFFSET;
	u32 cr1;
	u32 dmacr = 0;

	cr0 |= rs->rsd << CR0_RSD_OFFSET;
	cr0 |= (spi->mode & 0x3U) << CR0_SCPH_OFFSET;
	if (spi->mode & SPI_LSB_FIRST)
		cr0 |= CR0_FBM_LSB << CR0_FBM_OFFSET;

	if (xfer->rx_buf && xfer->tx_buf)
		cr0 |= CR0_XFM_TR << CR0_XFM_OFFSET;
	else if (xfer->rx_buf)
		cr0 |= CR0_XFM_RO << CR0_XFM_OFFSET;
	else if (use_dma)
		cr0 |= CR0_XFM_TO << CR0_XFM_OFFSET;

	switch (xfer->bits_per_word) {
	case 4:
		cr0 |= CR0_DFS_4BIT << CR0_DFS_OFFSET;
		cr1 = xfer->len - 1;
		break;
	case 8:
		cr0 |= CR0_DFS_8BIT << CR0_DFS_OFFSET;
		cr1 = xfer->len - 1;
		break;
	case 16:
		cr0 |= CR0_DFS_16BIT << CR0_DFS_OFFSET;
		cr1 = xfer->len / 2 - 1;
		break;
	default:
		/* we only whitelist 4, 8 and 16 bit words in
		 * master->bits_per_word_mask, so this shouldn't
		 * happen
		 */
		unreachable();
	}

	if (use_dma) {
		if (xfer->tx_buf)
			dmacr |= TF_DMA_EN;
		if (xfer->rx_buf)
			dmacr |= RF_DMA_EN;
	}

	writel_relaxed(cr0, rs->regs + ROCKCHIP_SPI_CTRLR0);
	writel_relaxed(cr1, rs->regs + ROCKCHIP_SPI_CTRLR1);

	/* unfortunately setting the fifo threshold level to generate an
	 * interrupt exactly when the fifo is full doesn't seem to work,
	 * so we need the strict inequality here
	 */
	if (xfer->len < rs->fifo_len)
		writel_relaxed(xfer->len - 1, rs->regs + ROCKCHIP_SPI_RXFTLR);
	else
		writel_relaxed(rs->fifo_len / 2 - 1, rs->regs + ROCKCHIP_SPI_RXFTLR);

	writel_relaxed(rs->fifo_len / 2 - 1, rs->regs + ROCKCHIP_SPI_DMATDLR);
	writel_relaxed(0, rs->regs + ROCKCHIP_SPI_DMARDLR);
	writel_relaxed(dmacr, rs->regs + ROCKCHIP_SPI_DMACR);

	/* the hardware only supports an even clock divisor, so
	 * round divisor = spiclk / speed up to nearest even number
	 * so that the resulting speed is <= the requested speed
	 */
	writel_relaxed(2 * DIV_ROUND_UP(rs->freq, 2 * xfer->speed_hz),
			rs->regs + ROCKCHIP_SPI_BAUDR);
}

static size_t rockchip_spi_max_transfer_size(struct spi_device *spi)
{
	return ROCKCHIP_SPI_MAX_TRANLEN;
}

static int rockchip_spi_transfer_one(
		struct spi_master *master,
		struct spi_device *spi,
		struct spi_transfer *xfer)
{
	struct rockchip_spi *rs = spi_master_get_devdata(master);
	bool use_dma;

	WARN_ON(readl_relaxed(rs->regs + ROCKCHIP_SPI_SSIENR) &&
		(readl_relaxed(rs->regs + ROCKCHIP_SPI_SR) & SR_BUSY));

	if (!xfer->tx_buf && !xfer->rx_buf) {
		dev_err(rs->dev, "No buffer for transfer\n");
		return -EINVAL;
	}

	if (xfer->len > ROCKCHIP_SPI_MAX_TRANLEN) {
		dev_err(rs->dev, "Transfer is too long (%d)\n", xfer->len);
		return -EINVAL;
	}

	rs->n_bytes = xfer->bits_per_word <= 8 ? 1 : 2;

	use_dma = master->can_dma ? master->can_dma(master, spi, xfer) : false;

	rockchip_spi_config(rs, spi, xfer, use_dma);

	if (use_dma)
		return rockchip_spi_prepare_dma(rs, master, xfer);

	return rockchip_spi_prepare_irq(rs, xfer);
}

static bool rockchip_spi_can_dma(struct spi_master *master,
				 struct spi_device *spi,
				 struct spi_transfer *xfer)
{
	struct rockchip_spi *rs = spi_master_get_devdata(master);
	unsigned int bytes_per_word = xfer->bits_per_word <= 8 ? 1 : 2;

	/* if the numbor of spi words to transfer is less than the fifo
	 * length we can just fill the fifo and wait for a single irq,
	 * so don't bother setting up dma
	 */
	return xfer->len / bytes_per_word >= rs->fifo_len;
}

static int rockchip_spi_probe(struct platform_device *pdev)
{
	int ret;
	struct rockchip_spi *rs;
	struct spi_master *master;
	struct resource *mem;
	u32 rsd_nsecs;

	master = spi_alloc_master(&pdev->dev, sizeof(struct rockchip_spi));
	if (!master)
		return -ENOMEM;

	platform_set_drvdata(pdev, master);

	rs = spi_master_get_devdata(master);

	/* Get basic io resource and map it */
	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	rs->regs = devm_ioremap_resource(&pdev->dev, mem);
	if (IS_ERR(rs->regs)) {
		ret =  PTR_ERR(rs->regs);
		goto err_put_master;
	}

	rs->apb_pclk = devm_clk_get(&pdev->dev, "apb_pclk");
	if (IS_ERR(rs->apb_pclk)) {
		dev_err(&pdev->dev, "Failed to get apb_pclk\n");
		ret = PTR_ERR(rs->apb_pclk);
		goto err_put_master;
	}

	rs->spiclk = devm_clk_get(&pdev->dev, "spiclk");
	if (IS_ERR(rs->spiclk)) {
		dev_err(&pdev->dev, "Failed to get spi_pclk\n");
		ret = PTR_ERR(rs->spiclk);
		goto err_put_master;
	}

	ret = clk_prepare_enable(rs->apb_pclk);
	if (ret < 0) {
		dev_err(&pdev->dev, "Failed to enable apb_pclk\n");
		goto err_put_master;
	}

	ret = clk_prepare_enable(rs->spiclk);
	if (ret < 0) {
		dev_err(&pdev->dev, "Failed to enable spi_clk\n");
		goto err_disable_apbclk;
	}

	spi_enable_chip(rs, false);

	ret = platform_get_irq(pdev, 0);
	if (ret < 0)
		goto err_disable_spiclk;

	ret = devm_request_threaded_irq(&pdev->dev, ret, rockchip_spi_isr, NULL,
			IRQF_ONESHOT, dev_name(&pdev->dev), master);
	if (ret)
		goto err_disable_spiclk;

	rs->dev = &pdev->dev;
	rs->freq = clk_get_rate(rs->spiclk);

	if (!of_property_read_u32(pdev->dev.of_node, "rx-sample-delay-ns",
				  &rsd_nsecs)) {
		/* rx sample delay is expressed in parent clock cycles (max 3) */
		u32 rsd = DIV_ROUND_CLOSEST(rsd_nsecs * (rs->freq >> 8),
				1000000000 >> 8);
		if (!rsd) {
			dev_warn(rs->dev, "%u Hz are too slow to express %u ns delay\n",
					rs->freq, rsd_nsecs);
		} else if (rsd > CR0_RSD_MAX) {
			rsd = CR0_RSD_MAX;
			dev_warn(rs->dev, "%u Hz are too fast to express %u ns delay, clamping at %u ns\n",
					rs->freq, rsd_nsecs,
					CR0_RSD_MAX * 1000000000U / rs->freq);
		}
		rs->rsd = rsd;
	}

	rs->fifo_len = get_fifo_len(rs);
	if (!rs->fifo_len) {
		dev_err(&pdev->dev, "Failed to get fifo length\n");
		ret = -EINVAL;
		goto err_disable_spiclk;
	}

	pm_runtime_set_active(&pdev->dev);
	pm_runtime_enable(&pdev->dev);

	master->auto_runtime_pm = true;
	master->bus_num = pdev->id;
	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LOOP | SPI_LSB_FIRST;
	master->num_chipselect = ROCKCHIP_SPI_MAX_CS_NUM;
	master->dev.of_node = pdev->dev.of_node;
	master->bits_per_word_mask = SPI_BPW_MASK(16) | SPI_BPW_MASK(8) | SPI_BPW_MASK(4);
	master->min_speed_hz = rs->freq / BAUDR_SCKDV_MAX;
	master->max_speed_hz = min(rs->freq / BAUDR_SCKDV_MIN, MAX_SCLK_OUT);

	master->set_cs = rockchip_spi_set_cs;
	master->transfer_one = rockchip_spi_transfer_one;
	master->max_transfer_size = rockchip_spi_max_transfer_size;
	master->handle_err = rockchip_spi_handle_err;
	master->flags = SPI_MASTER_GPIO_SS;

	master->dma_tx = dma_request_chan(rs->dev, "tx");
	if (IS_ERR(master->dma_tx)) {
		/* Check tx to see if we need defer probing driver */
		if (PTR_ERR(master->dma_tx) == -EPROBE_DEFER) {
			ret = -EPROBE_DEFER;
			goto err_disable_pm_runtime;
		}
		dev_warn(rs->dev, "Failed to request TX DMA channel\n");
		master->dma_tx = NULL;
	}

	master->dma_rx = dma_request_chan(rs->dev, "rx");
	if (IS_ERR(master->dma_rx)) {
		if (PTR_ERR(master->dma_rx) == -EPROBE_DEFER) {
			ret = -EPROBE_DEFER;
			goto err_free_dma_tx;
		}
		dev_warn(rs->dev, "Failed to request RX DMA channel\n");
		master->dma_rx = NULL;
	}

	if (master->dma_tx && master->dma_rx) {
		rs->dma_addr_tx = mem->start + ROCKCHIP_SPI_TXDR;
		rs->dma_addr_rx = mem->start + ROCKCHIP_SPI_RXDR;
		master->can_dma = rockchip_spi_can_dma;
	}

	ret = devm_spi_register_master(&pdev->dev, master);
	if (ret < 0) {
		dev_err(&pdev->dev, "Failed to register master\n");
		goto err_free_dma_rx;
	}

	return 0;

err_free_dma_rx:
	if (master->dma_rx)
		dma_release_channel(master->dma_rx);
err_free_dma_tx:
	if (master->dma_tx)
		dma_release_channel(master->dma_tx);
err_disable_pm_runtime:
	pm_runtime_disable(&pdev->dev);
err_disable_spiclk:
	clk_disable_unprepare(rs->spiclk);
err_disable_apbclk:
	clk_disable_unprepare(rs->apb_pclk);
err_put_master:
	spi_master_put(master);

	return ret;
}

static int rockchip_spi_remove(struct platform_device *pdev)
{
	struct spi_master *master = spi_master_get(platform_get_drvdata(pdev));
	struct rockchip_spi *rs = spi_master_get_devdata(master);

	pm_runtime_get_sync(&pdev->dev);

	clk_disable_unprepare(rs->spiclk);
	clk_disable_unprepare(rs->apb_pclk);

	pm_runtime_put_noidle(&pdev->dev);
	pm_runtime_disable(&pdev->dev);
	pm_runtime_set_suspended(&pdev->dev);

	if (master->dma_tx)
		dma_release_channel(master->dma_tx);
	if (master->dma_rx)
		dma_release_channel(master->dma_rx);

	spi_master_put(master);

	return 0;
}

#ifdef CONFIG_PM_SLEEP
static int rockchip_spi_suspend(struct device *dev)
{
	int ret;
	struct spi_master *master = dev_get_drvdata(dev);

	ret = spi_master_suspend(master);
	if (ret < 0)
		return ret;

	ret = pm_runtime_force_suspend(dev);
	if (ret < 0)
		return ret;

	pinctrl_pm_select_sleep_state(dev);

	return 0;
}

static int rockchip_spi_resume(struct device *dev)
{
	int ret;
	struct spi_master *master = dev_get_drvdata(dev);
	struct rockchip_spi *rs = spi_master_get_devdata(master);

	pinctrl_pm_select_default_state(dev);

	ret = pm_runtime_force_resume(dev);
	if (ret < 0)
		return ret;

	ret = spi_master_resume(master);
	if (ret < 0) {
		clk_disable_unprepare(rs->spiclk);
		clk_disable_unprepare(rs->apb_pclk);
	}

	return 0;
}
#endif /* CONFIG_PM_SLEEP */

#ifdef CONFIG_PM
static int rockchip_spi_runtime_suspend(struct device *dev)
{
	struct spi_master *master = dev_get_drvdata(dev);
	struct rockchip_spi *rs = spi_master_get_devdata(master);

	clk_disable_unprepare(rs->spiclk);
	clk_disable_unprepare(rs->apb_pclk);

	return 0;
}

static int rockchip_spi_runtime_resume(struct device *dev)
{
	int ret;
	struct spi_master *master = dev_get_drvdata(dev);
	struct rockchip_spi *rs = spi_master_get_devdata(master);

	ret = clk_prepare_enable(rs->apb_pclk);
	if (ret < 0)
		return ret;

	ret = clk_prepare_enable(rs->spiclk);
	if (ret < 0)
		clk_disable_unprepare(rs->apb_pclk);

	return 0;
}
#endif /* CONFIG_PM */

static const struct dev_pm_ops rockchip_spi_pm = {
	SET_SYSTEM_SLEEP_PM_OPS(rockchip_spi_suspend, rockchip_spi_resume)
	SET_RUNTIME_PM_OPS(rockchip_spi_runtime_suspend,
			   rockchip_spi_runtime_resume, NULL)
};

static const struct of_device_id rockchip_spi_dt_match[] = {
	{ .compatible = "rockchip,rv1108-spi", },
	{ .compatible = "rockchip,rk3036-spi", },
	{ .compatible = "rockchip,rk3066-spi", },
	{ .compatible = "rockchip,rk3188-spi", },
	{ .compatible = "rockchip,rk3228-spi", },
	{ .compatible = "rockchip,rk3288-spi", },
	{ .compatible = "rockchip,rk3368-spi", },
	{ .compatible = "rockchip,rk3399-spi", },
	{ },
};
MODULE_DEVICE_TABLE(of, rockchip_spi_dt_match);

static struct platform_driver rockchip_spi_driver = {
	.driver = {
		.name	= DRIVER_NAME,
		.pm = &rockchip_spi_pm,
		.of_match_table = of_match_ptr(rockchip_spi_dt_match),
	},
	.probe = rockchip_spi_probe,
	.remove = rockchip_spi_remove,
};

module_platform_driver(rockchip_spi_driver);

MODULE_AUTHOR("Addy Ke <addy.ke@rock-chips.com>");
MODULE_DESCRIPTION("ROCKCHIP SPI Controller Driver");
MODULE_LICENSE("GPL v2");