summaryrefslogtreecommitdiffstats
path: root/drivers/net/can/sun4i_can.c
blob: b3f2f4fe5ee041e954ec503dcb014fc19896aba1 (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
/*
 * sun4i_can.c - CAN bus controller driver for Allwinner SUN4I&SUN7I based SoCs
 *
 * Copyright (C) 2013 Peter Chen
 * Copyright (C) 2015 Gerhard Bertelsmann
 * All rights reserved.
 *
 * Parts of this software are based on (derived from) the SJA1000 code by:
 *   Copyright (C) 2014 Oliver Hartkopp <oliver.hartkopp@volkswagen.de>
 *   Copyright (C) 2007 Wolfgang Grandegger <wg@grandegger.com>
 *   Copyright (C) 2002-2007 Volkswagen Group Electronic Research
 *   Copyright (C) 2003 Matthias Brukner, Trajet Gmbh, Rebenring 33,
 *   38106 Braunschweig, GERMANY
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of Volkswagen nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * Alternatively, provided that this notice is retained in full, this
 * software may be distributed under the terms of the GNU General
 * Public License ("GPL") version 2, in which case the provisions of the
 * GPL apply INSTEAD OF those given above.
 *
 * The provided data structures and external interfaces from this code
 * are not restricted to be used by modules with a GPL compatible license.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 *
 */

#include <linux/netdevice.h>
#include <linux/can.h>
#include <linux/can/dev.h>
#include <linux/can/error.h>
#include <linux/can/led.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>

#define DRV_NAME "sun4i_can"

/* Registers address (physical base address 0x01C2BC00) */
#define SUN4I_REG_MSEL_ADDR	0x0000	/* CAN Mode Select */
#define SUN4I_REG_CMD_ADDR	0x0004	/* CAN Command */
#define SUN4I_REG_STA_ADDR	0x0008	/* CAN Status */
#define SUN4I_REG_INT_ADDR	0x000c	/* CAN Interrupt Flag */
#define SUN4I_REG_INTEN_ADDR	0x0010	/* CAN Interrupt Enable */
#define SUN4I_REG_BTIME_ADDR	0x0014	/* CAN Bus Timing 0 */
#define SUN4I_REG_TEWL_ADDR	0x0018	/* CAN Tx Error Warning Limit */
#define SUN4I_REG_ERRC_ADDR	0x001c	/* CAN Error Counter */
#define SUN4I_REG_RMCNT_ADDR	0x0020	/* CAN Receive Message Counter */
#define SUN4I_REG_RBUFSA_ADDR	0x0024	/* CAN Receive Buffer Start Address */
#define SUN4I_REG_BUF0_ADDR	0x0040	/* CAN Tx/Rx Buffer 0 */
#define SUN4I_REG_BUF1_ADDR	0x0044	/* CAN Tx/Rx Buffer 1 */
#define SUN4I_REG_BUF2_ADDR	0x0048	/* CAN Tx/Rx Buffer 2 */
#define SUN4I_REG_BUF3_ADDR	0x004c	/* CAN Tx/Rx Buffer 3 */
#define SUN4I_REG_BUF4_ADDR	0x0050	/* CAN Tx/Rx Buffer 4 */
#define SUN4I_REG_BUF5_ADDR	0x0054	/* CAN Tx/Rx Buffer 5 */
#define SUN4I_REG_BUF6_ADDR	0x0058	/* CAN Tx/Rx Buffer 6 */
#define SUN4I_REG_BUF7_ADDR	0x005c	/* CAN Tx/Rx Buffer 7 */
#define SUN4I_REG_BUF8_ADDR	0x0060	/* CAN Tx/Rx Buffer 8 */
#define SUN4I_REG_BUF9_ADDR	0x0064	/* CAN Tx/Rx Buffer 9 */
#define SUN4I_REG_BUF10_ADDR	0x0068	/* CAN Tx/Rx Buffer 10 */
#define SUN4I_REG_BUF11_ADDR	0x006c	/* CAN Tx/Rx Buffer 11 */
#define SUN4I_REG_BUF12_ADDR	0x0070	/* CAN Tx/Rx Buffer 12 */
#define SUN4I_REG_ACPC_ADDR	0x0040	/* CAN Acceptance Code 0 */
#define SUN4I_REG_ACPM_ADDR	0x0044	/* CAN Acceptance Mask 0 */
#define SUN4I_REG_RBUF_RBACK_START_ADDR	0x0180	/* CAN transmit buffer start */
#define SUN4I_REG_RBUF_RBACK_END_ADDR	0x01b0	/* CAN transmit buffer end */

/* Controller Register Description */

/* mode select register (r/w)
 * offset:0x0000 default:0x0000_0001
 */
#define SUN4I_MSEL_SLEEP_MODE		(0x01 << 4) /* write in reset mode */
#define SUN4I_MSEL_WAKE_UP		(0x00 << 4)
#define SUN4I_MSEL_SINGLE_FILTER	(0x01 << 3) /* write in reset mode */
#define SUN4I_MSEL_DUAL_FILTERS		(0x00 << 3)
#define SUN4I_MSEL_LOOPBACK_MODE	BIT(2)
#define SUN4I_MSEL_LISTEN_ONLY_MODE	BIT(1)
#define SUN4I_MSEL_RESET_MODE		BIT(0)

/* command register (w)
 * offset:0x0004 default:0x0000_0000
 */
#define SUN4I_CMD_BUS_OFF_REQ	BIT(5)
#define SUN4I_CMD_SELF_RCV_REQ	BIT(4)
#define SUN4I_CMD_CLEAR_OR_FLAG	BIT(3)
#define SUN4I_CMD_RELEASE_RBUF	BIT(2)
#define SUN4I_CMD_ABORT_REQ	BIT(1)
#define SUN4I_CMD_TRANS_REQ	BIT(0)

/* status register (r)
 * offset:0x0008 default:0x0000_003c
 */
#define SUN4I_STA_BIT_ERR	(0x00 << 22)
#define SUN4I_STA_FORM_ERR	(0x01 << 22)
#define SUN4I_STA_STUFF_ERR	(0x02 << 22)
#define SUN4I_STA_OTHER_ERR	(0x03 << 22)
#define SUN4I_STA_MASK_ERR	(0x03 << 22)
#define SUN4I_STA_ERR_DIR	BIT(21)
#define SUN4I_STA_ERR_SEG_CODE	(0x1f << 16)
#define SUN4I_STA_START		(0x03 << 16)
#define SUN4I_STA_ID28_21	(0x02 << 16)
#define SUN4I_STA_ID20_18	(0x06 << 16)
#define SUN4I_STA_SRTR		(0x04 << 16)
#define SUN4I_STA_IDE		(0x05 << 16)
#define SUN4I_STA_ID17_13	(0x07 << 16)
#define SUN4I_STA_ID12_5	(0x0f << 16)
#define SUN4I_STA_ID4_0		(0x0e << 16)
#define SUN4I_STA_RTR		(0x0c << 16)
#define SUN4I_STA_RB1		(0x0d << 16)
#define SUN4I_STA_RB0		(0x09 << 16)
#define SUN4I_STA_DLEN		(0x0b << 16)
#define SUN4I_STA_DATA_FIELD	(0x0a << 16)
#define SUN4I_STA_CRC_SEQUENCE	(0x08 << 16)
#define SUN4I_STA_CRC_DELIMITER	(0x18 << 16)
#define SUN4I_STA_ACK		(0x19 << 16)
#define SUN4I_STA_ACK_DELIMITER	(0x1b << 16)
#define SUN4I_STA_END		(0x1a << 16)
#define SUN4I_STA_INTERMISSION	(0x12 << 16)
#define SUN4I_STA_ACTIVE_ERROR	(0x11 << 16)
#define SUN4I_STA_PASSIVE_ERROR	(0x16 << 16)
#define SUN4I_STA_TOLERATE_DOMINANT_BITS	(0x13 << 16)
#define SUN4I_STA_ERROR_DELIMITER	(0x17 << 16)
#define SUN4I_STA_OVERLOAD	(0x1c << 16)
#define SUN4I_STA_BUS_OFF	BIT(7)
#define SUN4I_STA_ERR_STA	BIT(6)
#define SUN4I_STA_TRANS_BUSY	BIT(5)
#define SUN4I_STA_RCV_BUSY	BIT(4)
#define SUN4I_STA_TRANS_OVER	BIT(3)
#define SUN4I_STA_TBUF_RDY	BIT(2)
#define SUN4I_STA_DATA_ORUN	BIT(1)
#define SUN4I_STA_RBUF_RDY	BIT(0)

/* interrupt register (r)
 * offset:0x000c default:0x0000_0000
 */
#define SUN4I_INT_BUS_ERR	BIT(7)
#define SUN4I_INT_ARB_LOST	BIT(6)
#define SUN4I_INT_ERR_PASSIVE	BIT(5)
#define SUN4I_INT_WAKEUP	BIT(4)
#define SUN4I_INT_DATA_OR	BIT(3)
#define SUN4I_INT_ERR_WRN	BIT(2)
#define SUN4I_INT_TBUF_VLD	BIT(1)
#define SUN4I_INT_RBUF_VLD	BIT(0)

/* interrupt enable register (r/w)
 * offset:0x0010 default:0x0000_0000
 */
#define SUN4I_INTEN_BERR	BIT(7)
#define SUN4I_INTEN_ARB_LOST	BIT(6)
#define SUN4I_INTEN_ERR_PASSIVE	BIT(5)
#define SUN4I_INTEN_WAKEUP	BIT(4)
#define SUN4I_INTEN_OR		BIT(3)
#define SUN4I_INTEN_ERR_WRN	BIT(2)
#define SUN4I_INTEN_TX		BIT(1)
#define SUN4I_INTEN_RX		BIT(0)

/* error code */
#define SUN4I_ERR_INRCV		(0x1 << 5)
#define SUN4I_ERR_INTRANS	(0x0 << 5)

/* filter mode */
#define SUN4I_FILTER_CLOSE	0
#define SUN4I_SINGLE_FLTER_MODE	1
#define SUN4I_DUAL_FILTER_MODE	2

/* message buffer flags */
#define SUN4I_MSG_EFF_FLAG	BIT(7)
#define SUN4I_MSG_RTR_FLAG	BIT(6)

/* max. number of interrupts handled in ISR */
#define SUN4I_CAN_MAX_IRQ	20
#define SUN4I_MODE_MAX_RETRIES	100

struct sun4ican_priv {
	struct can_priv can;
	void __iomem *base;
	struct clk *clk;
	spinlock_t cmdreg_lock;	/* lock for concurrent cmd register writes */
};

static const struct can_bittiming_const sun4ican_bittiming_const = {
	.name = DRV_NAME,
	.tseg1_min = 1,
	.tseg1_max = 16,
	.tseg2_min = 1,
	.tseg2_max = 8,
	.sjw_max = 4,
	.brp_min = 1,
	.brp_max = 64,
	.brp_inc = 1,
};

static void sun4i_can_write_cmdreg(struct sun4ican_priv *priv, u8 val)
{
	unsigned long flags;

	spin_lock_irqsave(&priv->cmdreg_lock, flags);
	writel(val, priv->base + SUN4I_REG_CMD_ADDR);
	spin_unlock_irqrestore(&priv->cmdreg_lock, flags);
}

static int set_normal_mode(struct net_device *dev)
{
	struct sun4ican_priv *priv = netdev_priv(dev);
	int retry = SUN4I_MODE_MAX_RETRIES;
	u32 mod_reg_val = 0;

	do {
		mod_reg_val = readl(priv->base + SUN4I_REG_MSEL_ADDR);
		mod_reg_val &= ~SUN4I_MSEL_RESET_MODE;
		writel(mod_reg_val, priv->base + SUN4I_REG_MSEL_ADDR);
	} while (retry-- && (mod_reg_val & SUN4I_MSEL_RESET_MODE));

	if (readl(priv->base + SUN4I_REG_MSEL_ADDR) & SUN4I_MSEL_RESET_MODE) {
		netdev_err(dev,
			   "setting controller into normal mode failed!\n");
		return -ETIMEDOUT;
	}

	return 0;
}

static int set_reset_mode(struct net_device *dev)
{
	struct sun4ican_priv *priv = netdev_priv(dev);
	int retry = SUN4I_MODE_MAX_RETRIES;
	u32 mod_reg_val = 0;

	do {
		mod_reg_val = readl(priv->base + SUN4I_REG_MSEL_ADDR);
		mod_reg_val |= SUN4I_MSEL_RESET_MODE;
		writel(mod_reg_val, priv->base + SUN4I_REG_MSEL_ADDR);
	} while (retry-- && !(mod_reg_val & SUN4I_MSEL_RESET_MODE));

	if (!(readl(priv->base + SUN4I_REG_MSEL_ADDR) &
	      SUN4I_MSEL_RESET_MODE)) {
		netdev_err(dev, "setting controller into reset mode failed!\n");
		return -ETIMEDOUT;
	}

	return 0;
}

/* bittiming is called in reset_mode only */
static int sun4ican_set_bittiming(struct net_device *dev)
{
	struct sun4ican_priv *priv = netdev_priv(dev);
	struct can_bittiming *bt = &priv->can.bittiming;
	u32 cfg;

	cfg = ((bt->brp - 1) & 0x3FF) |
	     (((bt->sjw - 1) & 0x3) << 14) |
	     (((bt->prop_seg + bt->phase_seg1 - 1) & 0xf) << 16) |
	     (((bt->phase_seg2 - 1) & 0x7) << 20);
	if (priv->can.ctrlmode & CAN_CTRLMODE_3_SAMPLES)
		cfg |= 0x800000;

	netdev_dbg(dev, "setting BITTIMING=0x%08x\n", cfg);
	writel(cfg, priv->base + SUN4I_REG_BTIME_ADDR);

	return 0;
}

static int sun4ican_get_berr_counter(const struct net_device *dev,
				     struct can_berr_counter *bec)
{
	struct sun4ican_priv *priv = netdev_priv(dev);
	u32 errors;
	int err;

	err = clk_prepare_enable(priv->clk);
	if (err) {
		netdev_err(dev, "could not enable clock\n");
		return err;
	}

	errors = readl(priv->base + SUN4I_REG_ERRC_ADDR);

	bec->txerr = errors & 0xFF;
	bec->rxerr = (errors >> 16) & 0xFF;

	clk_disable_unprepare(priv->clk);

	return 0;
}

static int sun4i_can_start(struct net_device *dev)
{
	struct sun4ican_priv *priv = netdev_priv(dev);
	int err;
	u32 mod_reg_val;

	/* we need to enter the reset mode */
	err = set_reset_mode(dev);
	if (err) {
		netdev_err(dev, "could not enter reset mode\n");
		return err;
	}

	/* set filters - we accept all */
	writel(0x00000000, priv->base + SUN4I_REG_ACPC_ADDR);
	writel(0xFFFFFFFF, priv->base + SUN4I_REG_ACPM_ADDR);

	/* clear error counters and error code capture */
	writel(0, priv->base + SUN4I_REG_ERRC_ADDR);

	/* enable interrupts */
	if (priv->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING)
		writel(0xFF, priv->base + SUN4I_REG_INTEN_ADDR);
	else
		writel(0xFF & ~SUN4I_INTEN_BERR,
		       priv->base + SUN4I_REG_INTEN_ADDR);

	/* enter the selected mode */
	mod_reg_val = readl(priv->base + SUN4I_REG_MSEL_ADDR);
	if (priv->can.ctrlmode & CAN_CTRLMODE_LOOPBACK)
		mod_reg_val |= SUN4I_MSEL_LOOPBACK_MODE;
	else if (priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)
		mod_reg_val |= SUN4I_MSEL_LISTEN_ONLY_MODE;
	writel(mod_reg_val, priv->base + SUN4I_REG_MSEL_ADDR);

	err = sun4ican_set_bittiming(dev);
	if (err)
		return err;

	/* we are ready to enter the normal mode */
	err = set_normal_mode(dev);
	if (err) {
		netdev_err(dev, "could not enter normal mode\n");
		return err;
	}

	priv->can.state = CAN_STATE_ERROR_ACTIVE;

	return 0;
}

static int sun4i_can_stop(struct net_device *dev)
{
	struct sun4ican_priv *priv = netdev_priv(dev);
	int err;

	priv->can.state = CAN_STATE_STOPPED;
	/* we need to enter reset mode */
	err = set_reset_mode(dev);
	if (err) {
		netdev_err(dev, "could not enter reset mode\n");
		return err;
	}

	/* disable all interrupts */
	writel(0, priv->base + SUN4I_REG_INTEN_ADDR);

	return 0;
}

static int sun4ican_set_mode(struct net_device *dev, enum can_mode mode)
{
	int err;

	switch (mode) {
	case CAN_MODE_START:
		err = sun4i_can_start(dev);
		if (err) {
			netdev_err(dev, "starting CAN controller failed!\n");
			return err;
		}
		if (netif_queue_stopped(dev))
			netif_wake_queue(dev);
		break;

	default:
		return -EOPNOTSUPP;
	}
	return 0;
}

/* transmit a CAN message
 * message layout in the sk_buff should be like this:
 * xx xx xx xx         ff         ll 00 11 22 33 44 55 66 77
 * [ can_id ] [flags] [len] [can data (up to 8 bytes]
 */
static netdev_tx_t sun4ican_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
	struct sun4ican_priv *priv = netdev_priv(dev);
	struct can_frame *cf = (struct can_frame *)skb->data;
	u8 dlc;
	u32 dreg, msg_flag_n;
	canid_t id;
	int i;

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

	netif_stop_queue(dev);

	id = cf->can_id;
	dlc = cf->can_dlc;
	msg_flag_n = dlc;

	if (id & CAN_RTR_FLAG)
		msg_flag_n |= SUN4I_MSG_RTR_FLAG;

	if (id & CAN_EFF_FLAG) {
		msg_flag_n |= SUN4I_MSG_EFF_FLAG;
		dreg = SUN4I_REG_BUF5_ADDR;
		writel((id >> 21) & 0xFF, priv->base + SUN4I_REG_BUF1_ADDR);
		writel((id >> 13) & 0xFF, priv->base + SUN4I_REG_BUF2_ADDR);
		writel((id >> 5)  & 0xFF, priv->base + SUN4I_REG_BUF3_ADDR);
		writel((id << 3)  & 0xF8, priv->base + SUN4I_REG_BUF4_ADDR);
	} else {
		dreg = SUN4I_REG_BUF3_ADDR;
		writel((id >> 3) & 0xFF, priv->base + SUN4I_REG_BUF1_ADDR);
		writel((id << 5) & 0xE0, priv->base + SUN4I_REG_BUF2_ADDR);
	}

	for (i = 0; i < dlc; i++)
		writel(cf->data[i], priv->base + (dreg + i * 4));

	writel(msg_flag_n, priv->base + SUN4I_REG_BUF0_ADDR);

	can_put_echo_skb(skb, dev, 0);

	if (priv->can.ctrlmode & CAN_CTRLMODE_LOOPBACK)
		sun4i_can_write_cmdreg(priv, SUN4I_CMD_SELF_RCV_REQ);
	else
		sun4i_can_write_cmdreg(priv, SUN4I_CMD_TRANS_REQ);

	return NETDEV_TX_OK;
}

static void sun4i_can_rx(struct net_device *dev)
{
	struct sun4ican_priv *priv = netdev_priv(dev);
	struct net_device_stats *stats = &dev->stats;
	struct can_frame *cf;
	struct sk_buff *skb;
	u8 fi;
	u32 dreg;
	canid_t id;
	int i;

	/* create zero'ed CAN frame buffer */
	skb = alloc_can_skb(dev, &cf);
	if (!skb)
		return;

	fi = readl(priv->base + SUN4I_REG_BUF0_ADDR);
	cf->can_dlc = get_can_dlc(fi & 0x0F);
	if (fi & SUN4I_MSG_EFF_FLAG) {
		dreg = SUN4I_REG_BUF5_ADDR;
		id = (readl(priv->base + SUN4I_REG_BUF1_ADDR) << 21) |
		     (readl(priv->base + SUN4I_REG_BUF2_ADDR) << 13) |
		     (readl(priv->base + SUN4I_REG_BUF3_ADDR) << 5)  |
		    ((readl(priv->base + SUN4I_REG_BUF4_ADDR) >> 3)  & 0x1f);
		id |= CAN_EFF_FLAG;
	} else {
		dreg = SUN4I_REG_BUF3_ADDR;
		id = (readl(priv->base + SUN4I_REG_BUF1_ADDR) << 3) |
		    ((readl(priv->base + SUN4I_REG_BUF2_ADDR) >> 5) & 0x7);
	}

	/* remote frame ? */
	if (fi & SUN4I_MSG_RTR_FLAG)
		id |= CAN_RTR_FLAG;
	else
		for (i = 0; i < cf->can_dlc; i++)
			cf->data[i] = readl(priv->base + dreg + i * 4);

	cf->can_id = id;

	sun4i_can_write_cmdreg(priv, SUN4I_CMD_RELEASE_RBUF);

	stats->rx_packets++;
	stats->rx_bytes += cf->can_dlc;
	netif_rx(skb);

	can_led_event(dev, CAN_LED_EVENT_RX);
}

static int sun4i_can_err(struct net_device *dev, u8 isrc, u8 status)
{
	struct sun4ican_priv *priv = netdev_priv(dev);
	struct net_device_stats *stats = &dev->stats;
	struct can_frame *cf;
	struct sk_buff *skb;
	enum can_state state = priv->can.state;
	enum can_state rx_state, tx_state;
	unsigned int rxerr, txerr, errc;
	u32 ecc, alc;

	/* we don't skip if alloc fails because we want the stats anyhow */
	skb = alloc_can_err_skb(dev, &cf);

	errc = readl(priv->base + SUN4I_REG_ERRC_ADDR);
	rxerr = (errc >> 16) & 0xFF;
	txerr = errc & 0xFF;

	if (skb) {
		cf->data[6] = txerr;
		cf->data[7] = rxerr;
	}

	if (isrc & SUN4I_INT_DATA_OR) {
		/* data overrun interrupt */
		netdev_dbg(dev, "data overrun interrupt\n");
		if (likely(skb)) {
			cf->can_id |= CAN_ERR_CRTL;
			cf->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
		}
		stats->rx_over_errors++;
		stats->rx_errors++;

		/* reset the CAN IP by entering reset mode
		 * ignoring timeout error
		 */
		set_reset_mode(dev);
		set_normal_mode(dev);

		/* clear bit */
		sun4i_can_write_cmdreg(priv, SUN4I_CMD_CLEAR_OR_FLAG);
	}
	if (isrc & SUN4I_INT_ERR_WRN) {
		/* error warning interrupt */
		netdev_dbg(dev, "error warning interrupt\n");

		if (status & SUN4I_STA_BUS_OFF)
			state = CAN_STATE_BUS_OFF;
		else if (status & SUN4I_STA_ERR_STA)
			state = CAN_STATE_ERROR_WARNING;
		else
			state = CAN_STATE_ERROR_ACTIVE;
	}
	if (isrc & SUN4I_INT_BUS_ERR) {
		/* bus error interrupt */
		netdev_dbg(dev, "bus error interrupt\n");
		priv->can.can_stats.bus_error++;
		stats->rx_errors++;

		if (likely(skb)) {
			ecc = readl(priv->base + SUN4I_REG_STA_ADDR);

			cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR;

			switch (ecc & SUN4I_STA_MASK_ERR) {
			case SUN4I_STA_BIT_ERR:
				cf->data[2] |= CAN_ERR_PROT_BIT;
				break;
			case SUN4I_STA_FORM_ERR:
				cf->data[2] |= CAN_ERR_PROT_FORM;
				break;
			case SUN4I_STA_STUFF_ERR:
				cf->data[2] |= CAN_ERR_PROT_STUFF;
				break;
			default:
				cf->data[3] = (ecc & SUN4I_STA_ERR_SEG_CODE)
					       >> 16;
				break;
			}
			/* error occurred during transmission? */
			if ((ecc & SUN4I_STA_ERR_DIR) == 0)
				cf->data[2] |= CAN_ERR_PROT_TX;
		}
	}
	if (isrc & SUN4I_INT_ERR_PASSIVE) {
		/* error passive interrupt */
		netdev_dbg(dev, "error passive interrupt\n");
		if (state == CAN_STATE_ERROR_PASSIVE)
			state = CAN_STATE_ERROR_WARNING;
		else
			state = CAN_STATE_ERROR_PASSIVE;
	}
	if (isrc & SUN4I_INT_ARB_LOST) {
		/* arbitration lost interrupt */
		netdev_dbg(dev, "arbitration lost interrupt\n");
		alc = readl(priv->base + SUN4I_REG_STA_ADDR);
		priv->can.can_stats.arbitration_lost++;
		if (likely(skb)) {
			cf->can_id |= CAN_ERR_LOSTARB;
			cf->data[0] = (alc >> 8) & 0x1f;
		}
	}

	if (state != priv->can.state) {
		tx_state = txerr >= rxerr ? state : 0;
		rx_state = txerr <= rxerr ? state : 0;

		if (likely(skb))
			can_change_state(dev, cf, tx_state, rx_state);
		else
			priv->can.state = state;
		if (state == CAN_STATE_BUS_OFF)
			can_bus_off(dev);
	}

	if (likely(skb)) {
		stats->rx_packets++;
		stats->rx_bytes += cf->can_dlc;
		netif_rx(skb);
	} else {
		return -ENOMEM;
	}

	return 0;
}

static irqreturn_t sun4i_can_interrupt(int irq, void *dev_id)
{
	struct net_device *dev = (struct net_device *)dev_id;
	struct sun4ican_priv *priv = netdev_priv(dev);
	struct net_device_stats *stats = &dev->stats;
	u8 isrc, status;
	int n = 0;

	while ((isrc = readl(priv->base + SUN4I_REG_INT_ADDR)) &&
	       (n < SUN4I_CAN_MAX_IRQ)) {
		n++;
		status = readl(priv->base + SUN4I_REG_STA_ADDR);

		if (isrc & SUN4I_INT_WAKEUP)
			netdev_warn(dev, "wakeup interrupt\n");

		if (isrc & SUN4I_INT_TBUF_VLD) {
			/* transmission complete interrupt */
			stats->tx_bytes +=
			    readl(priv->base +
				  SUN4I_REG_RBUF_RBACK_START_ADDR) & 0xf;
			stats->tx_packets++;
			can_get_echo_skb(dev, 0);
			netif_wake_queue(dev);
			can_led_event(dev, CAN_LED_EVENT_TX);
		}
		if ((isrc & SUN4I_INT_RBUF_VLD) &&
		    !(isrc & SUN4I_INT_DATA_OR)) {
			/* receive interrupt - don't read if overrun occurred */
			while (status & SUN4I_STA_RBUF_RDY) {
				/* RX buffer is not empty */
				sun4i_can_rx(dev);
				status = readl(priv->base + SUN4I_REG_STA_ADDR);
			}
		}
		if (isrc &
		    (SUN4I_INT_DATA_OR | SUN4I_INT_ERR_WRN | SUN4I_INT_BUS_ERR |
		     SUN4I_INT_ERR_PASSIVE | SUN4I_INT_ARB_LOST)) {
			/* error interrupt */
			if (sun4i_can_err(dev, isrc, status))
				netdev_err(dev, "can't allocate buffer - clearing pending interrupts\n");
		}
		/* clear interrupts */
		writel(isrc, priv->base + SUN4I_REG_INT_ADDR);
		readl(priv->base + SUN4I_REG_INT_ADDR);
	}
	if (n >= SUN4I_CAN_MAX_IRQ)
		netdev_dbg(dev, "%d messages handled in ISR", n);

	return (n) ? IRQ_HANDLED : IRQ_NONE;
}

static int sun4ican_open(struct net_device *dev)
{
	struct sun4ican_priv *priv = netdev_priv(dev);
	int err;

	/* common open */
	err = open_candev(dev);
	if (err)
		return err;

	/* register interrupt handler */
	err = request_irq(dev->irq, sun4i_can_interrupt, 0, dev->name, dev);
	if (err) {
		netdev_err(dev, "request_irq err: %d\n", err);
		goto exit_irq;
	}

	/* turn on clocking for CAN peripheral block */
	err = clk_prepare_enable(priv->clk);
	if (err) {
		netdev_err(dev, "could not enable CAN peripheral clock\n");
		goto exit_clock;
	}

	err = sun4i_can_start(dev);
	if (err) {
		netdev_err(dev, "could not start CAN peripheral\n");
		goto exit_can_start;
	}

	can_led_event(dev, CAN_LED_EVENT_OPEN);
	netif_start_queue(dev);

	return 0;

exit_can_start:
	clk_disable_unprepare(priv->clk);
exit_clock:
	free_irq(dev->irq, dev);
exit_irq:
	close_candev(dev);
	return err;
}

static int sun4ican_close(struct net_device *dev)
{
	struct sun4ican_priv *priv = netdev_priv(dev);

	netif_stop_queue(dev);
	sun4i_can_stop(dev);
	clk_disable_unprepare(priv->clk);

	free_irq(dev->irq, dev);
	close_candev(dev);
	can_led_event(dev, CAN_LED_EVENT_STOP);

	return 0;
}

static const struct net_device_ops sun4ican_netdev_ops = {
	.ndo_open = sun4ican_open,
	.ndo_stop = sun4ican_close,
	.ndo_start_xmit = sun4ican_start_xmit,
};

static const struct of_device_id sun4ican_of_match[] = {
	{.compatible = "allwinner,sun4i-a10-can"},
	{},
};

MODULE_DEVICE_TABLE(of, sun4ican_of_match);

static int sun4ican_remove(struct platform_device *pdev)
{
	struct net_device *dev = platform_get_drvdata(pdev);

	unregister_netdev(dev);
	free_candev(dev);

	return 0;
}

static int sun4ican_probe(struct platform_device *pdev)
{
	struct device_node *np = pdev->dev.of_node;
	struct clk *clk;
	void __iomem *addr;
	int err, irq;
	struct net_device *dev;
	struct sun4ican_priv *priv;

	clk = of_clk_get(np, 0);
	if (IS_ERR(clk)) {
		dev_err(&pdev->dev, "unable to request clock\n");
		err = -ENODEV;
		goto exit;
	}

	irq = platform_get_irq(pdev, 0);
	if (irq < 0) {
		err = -ENODEV;
		goto exit;
	}

	addr = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(addr)) {
		err = PTR_ERR(addr);
		goto exit;
	}

	dev = alloc_candev(sizeof(struct sun4ican_priv), 1);
	if (!dev) {
		dev_err(&pdev->dev,
			"could not allocate memory for CAN device\n");
		err = -ENOMEM;
		goto exit;
	}

	dev->netdev_ops = &sun4ican_netdev_ops;
	dev->irq = irq;
	dev->flags |= IFF_ECHO;

	priv = netdev_priv(dev);
	priv->can.clock.freq = clk_get_rate(clk);
	priv->can.bittiming_const = &sun4ican_bittiming_const;
	priv->can.do_set_mode = sun4ican_set_mode;
	priv->can.do_get_berr_counter = sun4ican_get_berr_counter;
	priv->can.ctrlmode_supported = CAN_CTRLMODE_BERR_REPORTING |
				       CAN_CTRLMODE_LISTENONLY |
				       CAN_CTRLMODE_LOOPBACK |
				       CAN_CTRLMODE_3_SAMPLES;
	priv->base = addr;
	priv->clk = clk;
	spin_lock_init(&priv->cmdreg_lock);

	platform_set_drvdata(pdev, dev);
	SET_NETDEV_DEV(dev, &pdev->dev);

	err = register_candev(dev);
	if (err) {
		dev_err(&pdev->dev, "registering %s failed (err=%d)\n",
			DRV_NAME, err);
		goto exit_free;
	}
	devm_can_led_init(dev);

	dev_info(&pdev->dev, "device registered (base=%p, irq=%d)\n",
		 priv->base, dev->irq);

	return 0;

exit_free:
	free_candev(dev);
exit:
	return err;
}

static struct platform_driver sun4i_can_driver = {
	.driver = {
		.name = DRV_NAME,
		.of_match_table = sun4ican_of_match,
	},
	.probe = sun4ican_probe,
	.remove = sun4ican_remove,
};

module_platform_driver(sun4i_can_driver);

MODULE_AUTHOR("Peter Chen <xingkongcp@gmail.com>");
MODULE_AUTHOR("Gerhard Bertelsmann <info@gerhard-bertelsmann.de>");
MODULE_LICENSE("Dual BSD/GPL");
MODULE_DESCRIPTION("CAN driver for Allwinner SoCs (A10/A20)");