summaryrefslogtreecommitdiff
path: root/drivers/net/can/spi/hi311x.c
blob: b87dc420428d99b51189412d6613d1d67388e861 (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
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
// SPDX-License-Identifier: GPL-2.0-only
/* CAN bus driver for Holt HI3110 CAN Controller with SPI Interface
 *
 * Copyright(C) Timesys Corporation 2016
 *
 * Based on Microchip 251x CAN Controller (mcp251x) Linux kernel driver
 * Copyright 2009 Christian Pellegrin EVOL S.r.l.
 * Copyright 2007 Raymarine UK, Ltd. All Rights Reserved.
 * Copyright 2006 Arcom Control Systems Ltd.
 *
 * Based on CAN bus driver for the CCAN controller written by
 * - Sascha Hauer, Marc Kleine-Budde, Pengutronix
 * - Simon Kallweit, intefo AG
 * Copyright 2007
 */

#include <linux/can/core.h>
#include <linux/can/dev.h>
#include <linux/clk.h>
#include <linux/completion.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/ethtool.h>
#include <linux/freezer.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/regulator/consumer.h>
#include <linux/slab.h>
#include <linux/spi/spi.h>
#include <linux/uaccess.h>

#define HI3110_MASTER_RESET 0x56
#define HI3110_READ_CTRL0 0xD2
#define HI3110_READ_CTRL1 0xD4
#define HI3110_READ_STATF 0xE2
#define HI3110_WRITE_CTRL0 0x14
#define HI3110_WRITE_CTRL1 0x16
#define HI3110_WRITE_INTE 0x1C
#define HI3110_WRITE_BTR0 0x18
#define HI3110_WRITE_BTR1 0x1A
#define HI3110_READ_BTR0 0xD6
#define HI3110_READ_BTR1 0xD8
#define HI3110_READ_INTF 0xDE
#define HI3110_READ_ERR 0xDC
#define HI3110_READ_FIFO_WOTIME 0x48
#define HI3110_WRITE_FIFO 0x12
#define HI3110_READ_MESSTAT 0xDA
#define HI3110_READ_REC 0xEA
#define HI3110_READ_TEC 0xEC

#define HI3110_CTRL0_MODE_MASK (7 << 5)
#define HI3110_CTRL0_NORMAL_MODE (0 << 5)
#define HI3110_CTRL0_LOOPBACK_MODE (1 << 5)
#define HI3110_CTRL0_MONITOR_MODE (2 << 5)
#define HI3110_CTRL0_SLEEP_MODE (3 << 5)
#define HI3110_CTRL0_INIT_MODE (4 << 5)

#define HI3110_CTRL1_TXEN BIT(7)

#define HI3110_INT_RXTMP BIT(7)
#define HI3110_INT_RXFIFO BIT(6)
#define HI3110_INT_TXCPLT BIT(5)
#define HI3110_INT_BUSERR BIT(4)
#define HI3110_INT_MCHG BIT(3)
#define HI3110_INT_WAKEUP BIT(2)
#define HI3110_INT_F1MESS BIT(1)
#define HI3110_INT_F0MESS BIT(0)

#define HI3110_ERR_BUSOFF BIT(7)
#define HI3110_ERR_TXERRP BIT(6)
#define HI3110_ERR_RXERRP BIT(5)
#define HI3110_ERR_BITERR BIT(4)
#define HI3110_ERR_FRMERR BIT(3)
#define HI3110_ERR_CRCERR BIT(2)
#define HI3110_ERR_ACKERR BIT(1)
#define HI3110_ERR_STUFERR BIT(0)
#define HI3110_ERR_PROTOCOL_MASK (0x1F)
#define HI3110_ERR_PASSIVE_MASK (0x60)

#define HI3110_STAT_RXFMTY BIT(1)
#define HI3110_STAT_BUSOFF BIT(2)
#define HI3110_STAT_ERRP BIT(3)
#define HI3110_STAT_ERRW BIT(4)
#define HI3110_STAT_TXMTY BIT(7)

#define HI3110_BTR0_SJW_SHIFT 6
#define HI3110_BTR0_BRP_SHIFT 0

#define HI3110_BTR1_SAMP_3PERBIT (1 << 7)
#define HI3110_BTR1_SAMP_1PERBIT (0 << 7)
#define HI3110_BTR1_TSEG2_SHIFT 4
#define HI3110_BTR1_TSEG1_SHIFT 0

#define HI3110_FIFO_WOTIME_TAG_OFF 0
#define HI3110_FIFO_WOTIME_ID_OFF 1
#define HI3110_FIFO_WOTIME_DLC_OFF 5
#define HI3110_FIFO_WOTIME_DAT_OFF 6

#define HI3110_FIFO_WOTIME_TAG_IDE BIT(7)
#define HI3110_FIFO_WOTIME_ID_RTR BIT(0)

#define HI3110_FIFO_TAG_OFF 0
#define HI3110_FIFO_ID_OFF 1
#define HI3110_FIFO_STD_DLC_OFF 3
#define HI3110_FIFO_STD_DATA_OFF 4
#define HI3110_FIFO_EXT_DLC_OFF 5
#define HI3110_FIFO_EXT_DATA_OFF 6

#define HI3110_CAN_MAX_DATA_LEN 8
#define HI3110_RX_BUF_LEN 15
#define HI3110_TX_STD_BUF_LEN 12
#define HI3110_TX_EXT_BUF_LEN 14
#define HI3110_CAN_FRAME_MAX_BITS 128
#define HI3110_EFF_FLAGS 0x18 /* IDE + SRR */

#define HI3110_TX_ECHO_SKB_MAX 1

#define HI3110_OST_DELAY_MS (10)

#define DEVICE_NAME "hi3110"

static const struct can_bittiming_const hi3110_bittiming_const = {
	.name = DEVICE_NAME,
	.tseg1_min = 2,
	.tseg1_max = 16,
	.tseg2_min = 2,
	.tseg2_max = 8,
	.sjw_max = 4,
	.brp_min = 1,
	.brp_max = 64,
	.brp_inc = 1,
};

enum hi3110_model {
	CAN_HI3110_HI3110 = 0x3110,
};

struct hi3110_priv {
	struct can_priv can;
	struct net_device *net;
	struct spi_device *spi;
	enum hi3110_model model;

	struct mutex hi3110_lock; /* SPI device lock */

	u8 *spi_tx_buf;
	u8 *spi_rx_buf;

	struct sk_buff *tx_skb;

	struct workqueue_struct *wq;
	struct work_struct tx_work;
	struct work_struct restart_work;

	int force_quit;
	int after_suspend;
#define HI3110_AFTER_SUSPEND_UP 1
#define HI3110_AFTER_SUSPEND_DOWN 2
#define HI3110_AFTER_SUSPEND_POWER 4
#define HI3110_AFTER_SUSPEND_RESTART 8
	int restart_tx;
	bool tx_busy;

	struct regulator *power;
	struct regulator *transceiver;
	struct clk *clk;
};

static void hi3110_clean(struct net_device *net)
{
	struct hi3110_priv *priv = netdev_priv(net);

	if (priv->tx_skb || priv->tx_busy)
		net->stats.tx_errors++;
	dev_kfree_skb(priv->tx_skb);
	if (priv->tx_busy)
		can_free_echo_skb(priv->net, 0, NULL);
	priv->tx_skb = NULL;
	priv->tx_busy = false;
}

/* Note about handling of error return of hi3110_spi_trans: accessing
 * registers via SPI is not really different conceptually than using
 * normal I/O assembler instructions, although it's much more
 * complicated from a practical POV. So it's not advisable to always
 * check the return value of this function. Imagine that every
 * read{b,l}, write{b,l} and friends would be bracketed in "if ( < 0)
 * error();", it would be a great mess (well there are some situation
 * when exception handling C++ like could be useful after all). So we
 * just check that transfers are OK at the beginning of our
 * conversation with the chip and to avoid doing really nasty things
 * (like injecting bogus packets in the network stack).
 */
static int hi3110_spi_trans(struct spi_device *spi, int len)
{
	struct hi3110_priv *priv = spi_get_drvdata(spi);
	struct spi_transfer t = {
		.tx_buf = priv->spi_tx_buf,
		.rx_buf = priv->spi_rx_buf,
		.len = len,
		.cs_change = 0,
	};
	struct spi_message m;
	int ret;

	spi_message_init(&m);
	spi_message_add_tail(&t, &m);

	ret = spi_sync(spi, &m);

	if (ret)
		dev_err(&spi->dev, "spi transfer failed: ret = %d\n", ret);
	return ret;
}

static int hi3110_cmd(struct spi_device *spi, u8 command)
{
	struct hi3110_priv *priv = spi_get_drvdata(spi);

	priv->spi_tx_buf[0] = command;
	dev_dbg(&spi->dev, "hi3110_cmd: %02X\n", command);

	return hi3110_spi_trans(spi, 1);
}

static u8 hi3110_read(struct spi_device *spi, u8 command)
{
	struct hi3110_priv *priv = spi_get_drvdata(spi);
	u8 val = 0;

	priv->spi_tx_buf[0] = command;
	hi3110_spi_trans(spi, 2);
	val = priv->spi_rx_buf[1];

	return val;
}

static void hi3110_write(struct spi_device *spi, u8 reg, u8 val)
{
	struct hi3110_priv *priv = spi_get_drvdata(spi);

	priv->spi_tx_buf[0] = reg;
	priv->spi_tx_buf[1] = val;
	hi3110_spi_trans(spi, 2);
}

static void hi3110_hw_tx_frame(struct spi_device *spi, u8 *buf, int len)
{
	struct hi3110_priv *priv = spi_get_drvdata(spi);

	priv->spi_tx_buf[0] = HI3110_WRITE_FIFO;
	memcpy(priv->spi_tx_buf + 1, buf, len);
	hi3110_spi_trans(spi, len + 1);
}

static void hi3110_hw_tx(struct spi_device *spi, struct can_frame *frame)
{
	u8 buf[HI3110_TX_EXT_BUF_LEN];

	buf[HI3110_FIFO_TAG_OFF] = 0;

	if (frame->can_id & CAN_EFF_FLAG) {
		/* Extended frame */
		buf[HI3110_FIFO_ID_OFF] = (frame->can_id & CAN_EFF_MASK) >> 21;
		buf[HI3110_FIFO_ID_OFF + 1] =
			(((frame->can_id & CAN_EFF_MASK) >> 13) & 0xe0) |
			HI3110_EFF_FLAGS |
			(((frame->can_id & CAN_EFF_MASK) >> 15) & 0x07);
		buf[HI3110_FIFO_ID_OFF + 2] =
			(frame->can_id & CAN_EFF_MASK) >> 7;
		buf[HI3110_FIFO_ID_OFF + 3] =
			((frame->can_id & CAN_EFF_MASK) << 1) |
			((frame->can_id & CAN_RTR_FLAG) ? 1 : 0);

		buf[HI3110_FIFO_EXT_DLC_OFF] = frame->len;

		memcpy(buf + HI3110_FIFO_EXT_DATA_OFF,
		       frame->data, frame->len);

		hi3110_hw_tx_frame(spi, buf, HI3110_TX_EXT_BUF_LEN -
				   (HI3110_CAN_MAX_DATA_LEN - frame->len));
	} else {
		/* Standard frame */
		buf[HI3110_FIFO_ID_OFF] =   (frame->can_id & CAN_SFF_MASK) >> 3;
		buf[HI3110_FIFO_ID_OFF + 1] =
			((frame->can_id & CAN_SFF_MASK) << 5) |
			((frame->can_id & CAN_RTR_FLAG) ? (1 << 4) : 0);

		buf[HI3110_FIFO_STD_DLC_OFF] = frame->len;

		memcpy(buf + HI3110_FIFO_STD_DATA_OFF,
		       frame->data, frame->len);

		hi3110_hw_tx_frame(spi, buf, HI3110_TX_STD_BUF_LEN -
				   (HI3110_CAN_MAX_DATA_LEN - frame->len));
	}
}

static void hi3110_hw_rx_frame(struct spi_device *spi, u8 *buf)
{
	struct hi3110_priv *priv = spi_get_drvdata(spi);

	priv->spi_tx_buf[0] = HI3110_READ_FIFO_WOTIME;
	hi3110_spi_trans(spi, HI3110_RX_BUF_LEN);
	memcpy(buf, priv->spi_rx_buf + 1, HI3110_RX_BUF_LEN - 1);
}

static void hi3110_hw_rx(struct spi_device *spi)
{
	struct hi3110_priv *priv = spi_get_drvdata(spi);
	struct sk_buff *skb;
	struct can_frame *frame;
	u8 buf[HI3110_RX_BUF_LEN - 1];

	skb = alloc_can_skb(priv->net, &frame);
	if (!skb) {
		priv->net->stats.rx_dropped++;
		return;
	}

	hi3110_hw_rx_frame(spi, buf);
	if (buf[HI3110_FIFO_WOTIME_TAG_OFF] & HI3110_FIFO_WOTIME_TAG_IDE) {
		/* IDE is recessive (1), indicating extended 29-bit frame */
		frame->can_id = CAN_EFF_FLAG;
		frame->can_id |=
			(buf[HI3110_FIFO_WOTIME_ID_OFF] << 21) |
			(((buf[HI3110_FIFO_WOTIME_ID_OFF + 1] & 0xE0) >> 5) << 18) |
			((buf[HI3110_FIFO_WOTIME_ID_OFF + 1] & 0x07) << 15) |
			(buf[HI3110_FIFO_WOTIME_ID_OFF + 2] << 7) |
			(buf[HI3110_FIFO_WOTIME_ID_OFF + 3] >> 1);
	} else {
		/* IDE is dominant (0), frame indicating standard 11-bit */
		frame->can_id =
			(buf[HI3110_FIFO_WOTIME_ID_OFF] << 3) |
			((buf[HI3110_FIFO_WOTIME_ID_OFF + 1] & 0xE0) >> 5);
	}

	/* Data length */
	frame->len = can_cc_dlc2len(buf[HI3110_FIFO_WOTIME_DLC_OFF] & 0x0F);

	if (buf[HI3110_FIFO_WOTIME_ID_OFF + 3] & HI3110_FIFO_WOTIME_ID_RTR) {
		frame->can_id |= CAN_RTR_FLAG;
	} else {
		memcpy(frame->data, buf + HI3110_FIFO_WOTIME_DAT_OFF,
		       frame->len);

		priv->net->stats.rx_bytes += frame->len;
	}
	priv->net->stats.rx_packets++;

	netif_rx(skb);
}

static void hi3110_hw_sleep(struct spi_device *spi)
{
	hi3110_write(spi, HI3110_WRITE_CTRL0, HI3110_CTRL0_SLEEP_MODE);
}

static netdev_tx_t hi3110_hard_start_xmit(struct sk_buff *skb,
					  struct net_device *net)
{
	struct hi3110_priv *priv = netdev_priv(net);
	struct spi_device *spi = priv->spi;

	if (priv->tx_skb || priv->tx_busy) {
		dev_err(&spi->dev, "hard_xmit called while tx busy\n");
		return NETDEV_TX_BUSY;
	}

	if (can_dropped_invalid_skb(net, skb))
		return NETDEV_TX_OK;

	netif_stop_queue(net);
	priv->tx_skb = skb;
	queue_work(priv->wq, &priv->tx_work);

	return NETDEV_TX_OK;
}

static int hi3110_do_set_mode(struct net_device *net, enum can_mode mode)
{
	struct hi3110_priv *priv = netdev_priv(net);

	switch (mode) {
	case CAN_MODE_START:
		hi3110_clean(net);
		/* We have to delay work since SPI I/O may sleep */
		priv->can.state = CAN_STATE_ERROR_ACTIVE;
		priv->restart_tx = 1;
		if (priv->can.restart_ms == 0)
			priv->after_suspend = HI3110_AFTER_SUSPEND_RESTART;
		queue_work(priv->wq, &priv->restart_work);
		break;
	default:
		return -EOPNOTSUPP;
	}

	return 0;
}

static int hi3110_get_berr_counter(const struct net_device *net,
				   struct can_berr_counter *bec)
{
	struct hi3110_priv *priv = netdev_priv(net);
	struct spi_device *spi = priv->spi;

	mutex_lock(&priv->hi3110_lock);
	bec->txerr = hi3110_read(spi, HI3110_READ_TEC);
	bec->rxerr = hi3110_read(spi, HI3110_READ_REC);
	mutex_unlock(&priv->hi3110_lock);

	return 0;
}

static int hi3110_set_normal_mode(struct spi_device *spi)
{
	struct hi3110_priv *priv = spi_get_drvdata(spi);
	u8 reg = 0;

	hi3110_write(spi, HI3110_WRITE_INTE, HI3110_INT_BUSERR |
		     HI3110_INT_RXFIFO | HI3110_INT_TXCPLT);

	/* Enable TX */
	hi3110_write(spi, HI3110_WRITE_CTRL1, HI3110_CTRL1_TXEN);

	if (priv->can.ctrlmode & CAN_CTRLMODE_LOOPBACK)
		reg = HI3110_CTRL0_LOOPBACK_MODE;
	else if (priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)
		reg = HI3110_CTRL0_MONITOR_MODE;
	else
		reg = HI3110_CTRL0_NORMAL_MODE;

	hi3110_write(spi, HI3110_WRITE_CTRL0, reg);

	/* Wait for the device to enter the mode */
	mdelay(HI3110_OST_DELAY_MS);
	reg = hi3110_read(spi, HI3110_READ_CTRL0);
	if ((reg & HI3110_CTRL0_MODE_MASK) != reg)
		return -EBUSY;

	priv->can.state = CAN_STATE_ERROR_ACTIVE;
	return 0;
}

static int hi3110_do_set_bittiming(struct net_device *net)
{
	struct hi3110_priv *priv = netdev_priv(net);
	struct can_bittiming *bt = &priv->can.bittiming;
	struct spi_device *spi = priv->spi;

	hi3110_write(spi, HI3110_WRITE_BTR0,
		     ((bt->sjw - 1) << HI3110_BTR0_SJW_SHIFT) |
		     ((bt->brp - 1) << HI3110_BTR0_BRP_SHIFT));

	hi3110_write(spi, HI3110_WRITE_BTR1,
		     (priv->can.ctrlmode &
		      CAN_CTRLMODE_3_SAMPLES ?
		      HI3110_BTR1_SAMP_3PERBIT : HI3110_BTR1_SAMP_1PERBIT) |
		     ((bt->phase_seg1 + bt->prop_seg - 1)
		      << HI3110_BTR1_TSEG1_SHIFT) |
		     ((bt->phase_seg2 - 1) << HI3110_BTR1_TSEG2_SHIFT));

	dev_dbg(&spi->dev, "BT: 0x%02x 0x%02x\n",
		hi3110_read(spi, HI3110_READ_BTR0),
		hi3110_read(spi, HI3110_READ_BTR1));

	return 0;
}

static int hi3110_setup(struct net_device *net)
{
	hi3110_do_set_bittiming(net);
	return 0;
}

static int hi3110_hw_reset(struct spi_device *spi)
{
	u8 reg;
	int ret;

	/* Wait for oscillator startup timer after power up */
	mdelay(HI3110_OST_DELAY_MS);

	ret = hi3110_cmd(spi, HI3110_MASTER_RESET);
	if (ret)
		return ret;

	/* Wait for oscillator startup timer after reset */
	mdelay(HI3110_OST_DELAY_MS);

	reg = hi3110_read(spi, HI3110_READ_CTRL0);
	if ((reg & HI3110_CTRL0_MODE_MASK) != HI3110_CTRL0_INIT_MODE)
		return -ENODEV;

	/* As per the datasheet it appears the error flags are
	 * not cleared on reset. Explicitly clear them by performing a read
	 */
	hi3110_read(spi, HI3110_READ_ERR);

	return 0;
}

static int hi3110_hw_probe(struct spi_device *spi)
{
	u8 statf;

	hi3110_hw_reset(spi);

	/* Confirm correct operation by checking against reset values
	 * in datasheet
	 */
	statf = hi3110_read(spi, HI3110_READ_STATF);

	dev_dbg(&spi->dev, "statf: %02X\n", statf);

	if (statf != 0x82)
		return -ENODEV;

	return 0;
}

static int hi3110_power_enable(struct regulator *reg, int enable)
{
	if (IS_ERR_OR_NULL(reg))
		return 0;

	if (enable)
		return regulator_enable(reg);
	else
		return regulator_disable(reg);
}

static int hi3110_stop(struct net_device *net)
{
	struct hi3110_priv *priv = netdev_priv(net);
	struct spi_device *spi = priv->spi;

	close_candev(net);

	priv->force_quit = 1;
	free_irq(spi->irq, priv);
	destroy_workqueue(priv->wq);
	priv->wq = NULL;

	mutex_lock(&priv->hi3110_lock);

	/* Disable transmit, interrupts and clear flags */
	hi3110_write(spi, HI3110_WRITE_CTRL1, 0x0);
	hi3110_write(spi, HI3110_WRITE_INTE, 0x0);
	hi3110_read(spi, HI3110_READ_INTF);

	hi3110_clean(net);

	hi3110_hw_sleep(spi);

	hi3110_power_enable(priv->transceiver, 0);

	priv->can.state = CAN_STATE_STOPPED;

	mutex_unlock(&priv->hi3110_lock);

	return 0;
}

static void hi3110_tx_work_handler(struct work_struct *ws)
{
	struct hi3110_priv *priv = container_of(ws, struct hi3110_priv,
						tx_work);
	struct spi_device *spi = priv->spi;
	struct net_device *net = priv->net;
	struct can_frame *frame;

	mutex_lock(&priv->hi3110_lock);
	if (priv->tx_skb) {
		if (priv->can.state == CAN_STATE_BUS_OFF) {
			hi3110_clean(net);
		} else {
			frame = (struct can_frame *)priv->tx_skb->data;
			hi3110_hw_tx(spi, frame);
			priv->tx_busy = true;
			can_put_echo_skb(priv->tx_skb, net, 0, 0);
			priv->tx_skb = NULL;
		}
	}
	mutex_unlock(&priv->hi3110_lock);
}

static void hi3110_restart_work_handler(struct work_struct *ws)
{
	struct hi3110_priv *priv = container_of(ws, struct hi3110_priv,
						restart_work);
	struct spi_device *spi = priv->spi;
	struct net_device *net = priv->net;

	mutex_lock(&priv->hi3110_lock);
	if (priv->after_suspend) {
		hi3110_hw_reset(spi);
		hi3110_setup(net);
		if (priv->after_suspend & HI3110_AFTER_SUSPEND_RESTART) {
			hi3110_set_normal_mode(spi);
		} else if (priv->after_suspend & HI3110_AFTER_SUSPEND_UP) {
			netif_device_attach(net);
			hi3110_clean(net);
			hi3110_set_normal_mode(spi);
			netif_wake_queue(net);
		} else {
			hi3110_hw_sleep(spi);
		}
		priv->after_suspend = 0;
		priv->force_quit = 0;
	}

	if (priv->restart_tx) {
		priv->restart_tx = 0;
		hi3110_hw_reset(spi);
		hi3110_setup(net);
		hi3110_clean(net);
		hi3110_set_normal_mode(spi);
		netif_wake_queue(net);
	}
	mutex_unlock(&priv->hi3110_lock);
}

static irqreturn_t hi3110_can_ist(int irq, void *dev_id)
{
	struct hi3110_priv *priv = dev_id;
	struct spi_device *spi = priv->spi;
	struct net_device *net = priv->net;

	mutex_lock(&priv->hi3110_lock);

	while (!priv->force_quit) {
		enum can_state new_state;
		u8 intf, eflag, statf;

		while (!(HI3110_STAT_RXFMTY &
			 (statf = hi3110_read(spi, HI3110_READ_STATF)))) {
			hi3110_hw_rx(spi);
		}

		intf = hi3110_read(spi, HI3110_READ_INTF);
		eflag = hi3110_read(spi, HI3110_READ_ERR);
		/* Update can state */
		if (eflag & HI3110_ERR_BUSOFF)
			new_state = CAN_STATE_BUS_OFF;
		else if (eflag & HI3110_ERR_PASSIVE_MASK)
			new_state = CAN_STATE_ERROR_PASSIVE;
		else if (statf & HI3110_STAT_ERRW)
			new_state = CAN_STATE_ERROR_WARNING;
		else
			new_state = CAN_STATE_ERROR_ACTIVE;

		if (new_state != priv->can.state) {
			struct can_frame *cf;
			struct sk_buff *skb;
			enum can_state rx_state, tx_state;
			u8 rxerr, txerr;

			skb = alloc_can_err_skb(net, &cf);
			if (!skb)
				break;

			txerr = hi3110_read(spi, HI3110_READ_TEC);
			rxerr = hi3110_read(spi, HI3110_READ_REC);
			tx_state = txerr >= rxerr ? new_state : 0;
			rx_state = txerr <= rxerr ? new_state : 0;
			can_change_state(net, cf, tx_state, rx_state);
			netif_rx(skb);

			if (new_state == CAN_STATE_BUS_OFF) {
				can_bus_off(net);
				if (priv->can.restart_ms == 0) {
					priv->force_quit = 1;
					hi3110_hw_sleep(spi);
					break;
				}
			} else {
				cf->can_id |= CAN_ERR_CNT;
				cf->data[6] = txerr;
				cf->data[7] = rxerr;
			}
		}

		/* Update bus errors */
		if ((intf & HI3110_INT_BUSERR) &&
		    (priv->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING)) {
			struct can_frame *cf;
			struct sk_buff *skb;

			/* Check for protocol errors */
			if (eflag & HI3110_ERR_PROTOCOL_MASK) {
				skb = alloc_can_err_skb(net, &cf);
				if (!skb)
					break;

				cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR;
				priv->can.can_stats.bus_error++;
				priv->net->stats.rx_errors++;
				if (eflag & HI3110_ERR_BITERR)
					cf->data[2] |= CAN_ERR_PROT_BIT;
				else if (eflag & HI3110_ERR_FRMERR)
					cf->data[2] |= CAN_ERR_PROT_FORM;
				else if (eflag & HI3110_ERR_STUFERR)
					cf->data[2] |= CAN_ERR_PROT_STUFF;
				else if (eflag & HI3110_ERR_CRCERR)
					cf->data[3] |= CAN_ERR_PROT_LOC_CRC_SEQ;
				else if (eflag & HI3110_ERR_ACKERR)
					cf->data[3] |= CAN_ERR_PROT_LOC_ACK;

				cf->data[6] = hi3110_read(spi, HI3110_READ_TEC);
				cf->data[7] = hi3110_read(spi, HI3110_READ_REC);
				netdev_dbg(priv->net, "Bus Error\n");
				netif_rx(skb);
			}
		}

		if (priv->tx_busy && statf & HI3110_STAT_TXMTY) {
			net->stats.tx_packets++;
			net->stats.tx_bytes += can_get_echo_skb(net, 0, NULL);
			priv->tx_busy = false;
			netif_wake_queue(net);
		}

		if (intf == 0)
			break;
	}
	mutex_unlock(&priv->hi3110_lock);
	return IRQ_HANDLED;
}

static int hi3110_open(struct net_device *net)
{
	struct hi3110_priv *priv = netdev_priv(net);
	struct spi_device *spi = priv->spi;
	unsigned long flags = IRQF_ONESHOT | IRQF_TRIGGER_HIGH;
	int ret;

	ret = open_candev(net);
	if (ret)
		return ret;

	mutex_lock(&priv->hi3110_lock);
	hi3110_power_enable(priv->transceiver, 1);

	priv->force_quit = 0;
	priv->tx_skb = NULL;
	priv->tx_busy = false;

	ret = request_threaded_irq(spi->irq, NULL, hi3110_can_ist,
				   flags, DEVICE_NAME, priv);
	if (ret) {
		dev_err(&spi->dev, "failed to acquire irq %d\n", spi->irq);
		goto out_close;
	}

	priv->wq = alloc_workqueue("hi3110_wq", WQ_FREEZABLE | WQ_MEM_RECLAIM,
				   0);
	if (!priv->wq) {
		ret = -ENOMEM;
		goto out_free_irq;
	}
	INIT_WORK(&priv->tx_work, hi3110_tx_work_handler);
	INIT_WORK(&priv->restart_work, hi3110_restart_work_handler);

	ret = hi3110_hw_reset(spi);
	if (ret)
		goto out_free_wq;

	ret = hi3110_setup(net);
	if (ret)
		goto out_free_wq;

	ret = hi3110_set_normal_mode(spi);
	if (ret)
		goto out_free_wq;

	netif_wake_queue(net);
	mutex_unlock(&priv->hi3110_lock);

	return 0;

 out_free_wq:
	destroy_workqueue(priv->wq);
 out_free_irq:
	free_irq(spi->irq, priv);
	hi3110_hw_sleep(spi);
 out_close:
	hi3110_power_enable(priv->transceiver, 0);
	close_candev(net);
	mutex_unlock(&priv->hi3110_lock);
	return ret;
}

static const struct net_device_ops hi3110_netdev_ops = {
	.ndo_open = hi3110_open,
	.ndo_stop = hi3110_stop,
	.ndo_start_xmit = hi3110_hard_start_xmit,
};

static const struct ethtool_ops hi3110_ethtool_ops = {
	.get_ts_info = ethtool_op_get_ts_info,
};

static const struct of_device_id hi3110_of_match[] = {
	{
		.compatible	= "holt,hi3110",
		.data		= (void *)CAN_HI3110_HI3110,
	},
	{ }
};
MODULE_DEVICE_TABLE(of, hi3110_of_match);

static const struct spi_device_id hi3110_id_table[] = {
	{
		.name		= "hi3110",
		.driver_data	= (kernel_ulong_t)CAN_HI3110_HI3110,
	},
	{ }
};
MODULE_DEVICE_TABLE(spi, hi3110_id_table);

static int hi3110_can_probe(struct spi_device *spi)
{
	struct device *dev = &spi->dev;
	struct net_device *net;
	struct hi3110_priv *priv;
	const void *match;
	struct clk *clk;
	u32 freq;
	int ret;

	clk = devm_clk_get_optional(&spi->dev, NULL);
	if (IS_ERR(clk))
		return dev_err_probe(dev, PTR_ERR(clk), "no CAN clock source defined\n");

	if (clk) {
		freq = clk_get_rate(clk);
	} else {
		ret = device_property_read_u32(dev, "clock-frequency", &freq);
		if (ret)
			return dev_err_probe(dev, ret, "Failed to get clock-frequency!\n");
	}

	/* Sanity check */
	if (freq > 40000000)
		return -ERANGE;

	/* Allocate can/net device */
	net = alloc_candev(sizeof(struct hi3110_priv), HI3110_TX_ECHO_SKB_MAX);
	if (!net)
		return -ENOMEM;

	ret = clk_prepare_enable(clk);
	if (ret)
		goto out_free;

	net->netdev_ops = &hi3110_netdev_ops;
	net->ethtool_ops = &hi3110_ethtool_ops;
	net->flags |= IFF_ECHO;

	priv = netdev_priv(net);
	priv->can.bittiming_const = &hi3110_bittiming_const;
	priv->can.do_set_mode = hi3110_do_set_mode;
	priv->can.do_get_berr_counter = hi3110_get_berr_counter;
	priv->can.clock.freq = freq / 2;
	priv->can.ctrlmode_supported = CAN_CTRLMODE_3_SAMPLES |
		CAN_CTRLMODE_LOOPBACK |
		CAN_CTRLMODE_LISTENONLY |
		CAN_CTRLMODE_BERR_REPORTING;

	match = device_get_match_data(dev);
	if (match)
		priv->model = (enum hi3110_model)(uintptr_t)match;
	else
		priv->model = spi_get_device_id(spi)->driver_data;
	priv->net = net;
	priv->clk = clk;

	spi_set_drvdata(spi, priv);

	/* Configure the SPI bus */
	spi->bits_per_word = 8;
	ret = spi_setup(spi);
	if (ret)
		goto out_clk;

	priv->power = devm_regulator_get_optional(&spi->dev, "vdd");
	priv->transceiver = devm_regulator_get_optional(&spi->dev, "xceiver");
	if ((PTR_ERR(priv->power) == -EPROBE_DEFER) ||
	    (PTR_ERR(priv->transceiver) == -EPROBE_DEFER)) {
		ret = -EPROBE_DEFER;
		goto out_clk;
	}

	ret = hi3110_power_enable(priv->power, 1);
	if (ret)
		goto out_clk;

	priv->spi = spi;
	mutex_init(&priv->hi3110_lock);

	priv->spi_tx_buf = devm_kzalloc(&spi->dev, HI3110_RX_BUF_LEN,
					GFP_KERNEL);
	if (!priv->spi_tx_buf) {
		ret = -ENOMEM;
		goto error_probe;
	}
	priv->spi_rx_buf = devm_kzalloc(&spi->dev, HI3110_RX_BUF_LEN,
					GFP_KERNEL);

	if (!priv->spi_rx_buf) {
		ret = -ENOMEM;
		goto error_probe;
	}

	SET_NETDEV_DEV(net, &spi->dev);

	ret = hi3110_hw_probe(spi);
	if (ret) {
		dev_err_probe(dev, ret, "Cannot initialize %x. Wrong wiring?\n", priv->model);
		goto error_probe;
	}
	hi3110_hw_sleep(spi);

	ret = register_candev(net);
	if (ret)
		goto error_probe;

	netdev_info(net, "%x successfully initialized.\n", priv->model);

	return 0;

 error_probe:
	hi3110_power_enable(priv->power, 0);

 out_clk:
	clk_disable_unprepare(clk);

 out_free:
	free_candev(net);

	return dev_err_probe(dev, ret, "Probe failed\n");
}

static void hi3110_can_remove(struct spi_device *spi)
{
	struct hi3110_priv *priv = spi_get_drvdata(spi);
	struct net_device *net = priv->net;

	unregister_candev(net);

	hi3110_power_enable(priv->power, 0);

	clk_disable_unprepare(priv->clk);

	free_candev(net);
}

static int __maybe_unused hi3110_can_suspend(struct device *dev)
{
	struct spi_device *spi = to_spi_device(dev);
	struct hi3110_priv *priv = spi_get_drvdata(spi);
	struct net_device *net = priv->net;

	priv->force_quit = 1;
	disable_irq(spi->irq);

	/* Note: at this point neither IST nor workqueues are running.
	 * open/stop cannot be called anyway so locking is not needed
	 */
	if (netif_running(net)) {
		netif_device_detach(net);

		hi3110_hw_sleep(spi);
		hi3110_power_enable(priv->transceiver, 0);
		priv->after_suspend = HI3110_AFTER_SUSPEND_UP;
	} else {
		priv->after_suspend = HI3110_AFTER_SUSPEND_DOWN;
	}

	if (!IS_ERR_OR_NULL(priv->power)) {
		regulator_disable(priv->power);
		priv->after_suspend |= HI3110_AFTER_SUSPEND_POWER;
	}

	return 0;
}

static int __maybe_unused hi3110_can_resume(struct device *dev)
{
	struct spi_device *spi = to_spi_device(dev);
	struct hi3110_priv *priv = spi_get_drvdata(spi);

	if (priv->after_suspend & HI3110_AFTER_SUSPEND_POWER)
		hi3110_power_enable(priv->power, 1);

	if (priv->after_suspend & HI3110_AFTER_SUSPEND_UP) {
		hi3110_power_enable(priv->transceiver, 1);
		queue_work(priv->wq, &priv->restart_work);
	} else {
		priv->after_suspend = 0;
	}

	priv->force_quit = 0;
	enable_irq(spi->irq);
	return 0;
}

static SIMPLE_DEV_PM_OPS(hi3110_can_pm_ops, hi3110_can_suspend, hi3110_can_resume);

static struct spi_driver hi3110_can_driver = {
	.driver = {
		.name = DEVICE_NAME,
		.of_match_table = hi3110_of_match,
		.pm = &hi3110_can_pm_ops,
	},
	.id_table = hi3110_id_table,
	.probe = hi3110_can_probe,
	.remove = hi3110_can_remove,
};

module_spi_driver(hi3110_can_driver);

MODULE_AUTHOR("Akshay Bhat <akshay.bhat@timesys.com>");
MODULE_AUTHOR("Casey Fitzpatrick <casey.fitzpatrick@timesys.com>");
MODULE_DESCRIPTION("Holt HI-3110 CAN driver");
MODULE_LICENSE("GPL v2");