summaryrefslogtreecommitdiff
path: root/drivers/fsi/fsi-core.c
blob: e318bf8c623c66e33201d1592dba5a9b86f762c7 (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
/*
 * FSI core driver
 *
 * Copyright (C) IBM Corporation 2016
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that 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/crc4.h>
#include <linux/device.h>
#include <linux/fsi.h>
#include <linux/idr.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/bitops.h>

#include "fsi-master.h"

#define CREATE_TRACE_POINTS
#include <trace/events/fsi.h>

#define FSI_SLAVE_CONF_NEXT_MASK	GENMASK(31, 31)
#define FSI_SLAVE_CONF_SLOTS_MASK	GENMASK(23, 16)
#define FSI_SLAVE_CONF_SLOTS_SHIFT	16
#define FSI_SLAVE_CONF_VERSION_MASK	GENMASK(15, 12)
#define FSI_SLAVE_CONF_VERSION_SHIFT	12
#define FSI_SLAVE_CONF_TYPE_MASK	GENMASK(11, 4)
#define FSI_SLAVE_CONF_TYPE_SHIFT	4
#define FSI_SLAVE_CONF_CRC_SHIFT	4
#define FSI_SLAVE_CONF_CRC_MASK		GENMASK(3, 0)
#define FSI_SLAVE_CONF_DATA_BITS	28

#define FSI_PEEK_BASE			0x410

static const int engine_page_size = 0x400;

#define FSI_SLAVE_BASE			0x800

/*
 * FSI slave engine control register offsets
 */
#define FSI_SMODE		0x0	/* R/W: Mode register */
#define FSI_SISC		0x8	/* R/W: Interrupt condition */
#define FSI_SSTAT		0x14	/* R  : Slave status */
#define FSI_LLMODE		0x100	/* R/W: Link layer mode register */

/*
 * SMODE fields
 */
#define FSI_SMODE_WSC		0x80000000	/* Warm start done */
#define FSI_SMODE_ECRC		0x20000000	/* Hw CRC check */
#define FSI_SMODE_SID_SHIFT	24		/* ID shift */
#define FSI_SMODE_SID_MASK	3		/* ID Mask */
#define FSI_SMODE_ED_SHIFT	20		/* Echo delay shift */
#define FSI_SMODE_ED_MASK	0xf		/* Echo delay mask */
#define FSI_SMODE_SD_SHIFT	16		/* Send delay shift */
#define FSI_SMODE_SD_MASK	0xf		/* Send delay mask */
#define FSI_SMODE_LBCRR_SHIFT	8		/* Clk ratio shift */
#define FSI_SMODE_LBCRR_MASK	0xf		/* Clk ratio mask */

/*
 * LLMODE fields
 */
#define FSI_LLMODE_ASYNC	0x1

#define FSI_SLAVE_SIZE_23b		0x800000

static DEFINE_IDA(master_ida);

struct fsi_slave {
	struct device		dev;
	struct fsi_master	*master;
	int			id;
	int			link;
	uint32_t		size;	/* size of slave address space */
};

#define to_fsi_master(d) container_of(d, struct fsi_master, dev)
#define to_fsi_slave(d) container_of(d, struct fsi_slave, dev)

static const int slave_retries = 2;
static int discard_errors;

static int fsi_master_read(struct fsi_master *master, int link,
		uint8_t slave_id, uint32_t addr, void *val, size_t size);
static int fsi_master_write(struct fsi_master *master, int link,
		uint8_t slave_id, uint32_t addr, const void *val, size_t size);
static int fsi_master_break(struct fsi_master *master, int link);

/*
 * fsi_device_read() / fsi_device_write() / fsi_device_peek()
 *
 * FSI endpoint-device support
 *
 * Read / write / peek accessors for a client
 *
 * Parameters:
 * dev:  Structure passed to FSI client device drivers on probe().
 * addr: FSI address of given device.  Client should pass in its base address
 *       plus desired offset to access its register space.
 * val:  For read/peek this is the value read at the specified address. For
 *       write this is value to write to the specified address.
 *       The data in val must be FSI bus endian (big endian).
 * size: Size in bytes of the operation.  Sizes supported are 1, 2 and 4 bytes.
 *       Addresses must be aligned on size boundaries or an error will result.
 */
int fsi_device_read(struct fsi_device *dev, uint32_t addr, void *val,
		size_t size)
{
	if (addr > dev->size || size > dev->size || addr > dev->size - size)
		return -EINVAL;

	return fsi_slave_read(dev->slave, dev->addr + addr, val, size);
}
EXPORT_SYMBOL_GPL(fsi_device_read);

int fsi_device_write(struct fsi_device *dev, uint32_t addr, const void *val,
		size_t size)
{
	if (addr > dev->size || size > dev->size || addr > dev->size - size)
		return -EINVAL;

	return fsi_slave_write(dev->slave, dev->addr + addr, val, size);
}
EXPORT_SYMBOL_GPL(fsi_device_write);

int fsi_device_peek(struct fsi_device *dev, void *val)
{
	uint32_t addr = FSI_PEEK_BASE + ((dev->unit - 2) * sizeof(uint32_t));

	return fsi_slave_read(dev->slave, addr, val, sizeof(uint32_t));
}

static void fsi_device_release(struct device *_device)
{
	struct fsi_device *device = to_fsi_dev(_device);

	kfree(device);
}

static struct fsi_device *fsi_create_device(struct fsi_slave *slave)
{
	struct fsi_device *dev;

	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
	if (!dev)
		return NULL;

	dev->dev.parent = &slave->dev;
	dev->dev.bus = &fsi_bus_type;
	dev->dev.release = fsi_device_release;

	return dev;
}

/* FSI slave support */
static int fsi_slave_calc_addr(struct fsi_slave *slave, uint32_t *addrp,
		uint8_t *idp)
{
	uint32_t addr = *addrp;
	uint8_t id = *idp;

	if (addr > slave->size)
		return -EINVAL;

	/* For 23 bit addressing, we encode the extra two bits in the slave
	 * id (and the slave's actual ID needs to be 0).
	 */
	if (addr > 0x1fffff) {
		if (slave->id != 0)
			return -EINVAL;
		id = (addr >> 21) & 0x3;
		addr &= 0x1fffff;
	}

	*addrp = addr;
	*idp = id;
	return 0;
}

static int fsi_slave_report_and_clear_errors(struct fsi_slave *slave)
{
	struct fsi_master *master = slave->master;
	uint32_t irq, stat;
	int rc, link;
	uint8_t id;

	link = slave->link;
	id = slave->id;

	rc = fsi_master_read(master, link, id, FSI_SLAVE_BASE + FSI_SISC,
			&irq, sizeof(irq));
	if (rc)
		return rc;

	rc =  fsi_master_read(master, link, id, FSI_SLAVE_BASE + FSI_SSTAT,
			&stat, sizeof(stat));
	if (rc)
		return rc;

	dev_info(&slave->dev, "status: 0x%08x, sisc: 0x%08x\n",
			be32_to_cpu(stat), be32_to_cpu(irq));

	/* clear interrupts */
	return fsi_master_write(master, link, id, FSI_SLAVE_BASE + FSI_SISC,
			&irq, sizeof(irq));
}

static int fsi_slave_set_smode(struct fsi_master *master, int link, int id);

static int fsi_slave_handle_error(struct fsi_slave *slave, bool write,
				  uint32_t addr, size_t size)
{
	struct fsi_master *master = slave->master;
	int rc, link;
	uint32_t reg;
	uint8_t id;

	if (discard_errors)
		return -1;

	link = slave->link;
	id = slave->id;

	dev_dbg(&slave->dev, "handling error on %s to 0x%08x[%zd]",
			write ? "write" : "read", addr, size);

	/* try a simple clear of error conditions, which may fail if we've lost
	 * communication with the slave
	 */
	rc = fsi_slave_report_and_clear_errors(slave);
	if (!rc)
		return 0;

	/* send a TERM and retry */
	if (master->term) {
		rc = master->term(master, link, id);
		if (!rc) {
			rc = fsi_master_read(master, link, id, 0,
					&reg, sizeof(reg));
			if (!rc)
				rc = fsi_slave_report_and_clear_errors(slave);
			if (!rc)
				return 0;
		}
	}

	/* getting serious, reset the slave via BREAK */
	rc = fsi_master_break(master, link);
	if (rc)
		return rc;

	rc = fsi_slave_set_smode(master, link, id);
	if (rc)
		return rc;

	return fsi_slave_report_and_clear_errors(slave);
}

int fsi_slave_read(struct fsi_slave *slave, uint32_t addr,
			void *val, size_t size)
{
	uint8_t id = slave->id;
	int rc, err_rc, i;

	rc = fsi_slave_calc_addr(slave, &addr, &id);
	if (rc)
		return rc;

	for (i = 0; i < slave_retries; i++) {
		rc = fsi_master_read(slave->master, slave->link,
				id, addr, val, size);
		if (!rc)
			break;

		err_rc = fsi_slave_handle_error(slave, false, addr, size);
		if (err_rc)
			break;
	}

	return rc;
}
EXPORT_SYMBOL_GPL(fsi_slave_read);

int fsi_slave_write(struct fsi_slave *slave, uint32_t addr,
			const void *val, size_t size)
{
	uint8_t id = slave->id;
	int rc, err_rc, i;

	rc = fsi_slave_calc_addr(slave, &addr, &id);
	if (rc)
		return rc;

	for (i = 0; i < slave_retries; i++) {
		rc = fsi_master_write(slave->master, slave->link,
				id, addr, val, size);
		if (!rc)
			break;

		err_rc = fsi_slave_handle_error(slave, true, addr, size);
		if (err_rc)
			break;
	}

	return rc;
}
EXPORT_SYMBOL_GPL(fsi_slave_write);

extern int fsi_slave_claim_range(struct fsi_slave *slave,
		uint32_t addr, uint32_t size)
{
	if (addr + size < addr)
		return -EINVAL;

	if (addr + size > slave->size)
		return -EINVAL;

	/* todo: check for overlapping claims */
	return 0;
}
EXPORT_SYMBOL_GPL(fsi_slave_claim_range);

extern void fsi_slave_release_range(struct fsi_slave *slave,
		uint32_t addr, uint32_t size)
{
}
EXPORT_SYMBOL_GPL(fsi_slave_release_range);

static int fsi_slave_scan(struct fsi_slave *slave)
{
	uint32_t engine_addr;
	uint32_t conf;
	int rc, i;

	/*
	 * scan engines
	 *
	 * We keep the peek mode and slave engines for the core; so start
	 * at the third slot in the configuration table. We also need to
	 * skip the chip ID entry at the start of the address space.
	 */
	engine_addr = engine_page_size * 3;
	for (i = 2; i < engine_page_size / sizeof(uint32_t); i++) {
		uint8_t slots, version, type, crc;
		struct fsi_device *dev;

		rc = fsi_slave_read(slave, (i + 1) * sizeof(conf),
				&conf, sizeof(conf));
		if (rc) {
			dev_warn(&slave->dev,
				"error reading slave registers\n");
			return -1;
		}
		conf = be32_to_cpu(conf);

		crc = crc4(0, conf, 32);
		if (crc) {
			dev_warn(&slave->dev,
				"crc error in slave register at 0x%04x\n",
				i);
			return -1;
		}

		slots = (conf & FSI_SLAVE_CONF_SLOTS_MASK)
			>> FSI_SLAVE_CONF_SLOTS_SHIFT;
		version = (conf & FSI_SLAVE_CONF_VERSION_MASK)
			>> FSI_SLAVE_CONF_VERSION_SHIFT;
		type = (conf & FSI_SLAVE_CONF_TYPE_MASK)
			>> FSI_SLAVE_CONF_TYPE_SHIFT;

		/*
		 * Unused address areas are marked by a zero type value; this
		 * skips the defined address areas
		 */
		if (type != 0 && slots != 0) {

			/* create device */
			dev = fsi_create_device(slave);
			if (!dev)
				return -ENOMEM;

			dev->slave = slave;
			dev->engine_type = type;
			dev->version = version;
			dev->unit = i;
			dev->addr = engine_addr;
			dev->size = slots * engine_page_size;

			dev_dbg(&slave->dev,
			"engine[%i]: type %x, version %x, addr %x size %x\n",
					dev->unit, dev->engine_type, version,
					dev->addr, dev->size);

			dev_set_name(&dev->dev, "%02x:%02x:%02x:%02x",
					slave->master->idx, slave->link,
					slave->id, i - 2);

			rc = device_register(&dev->dev);
			if (rc) {
				dev_warn(&slave->dev, "add failed: %d\n", rc);
				put_device(&dev->dev);
			}
		}

		engine_addr += slots * engine_page_size;

		if (!(conf & FSI_SLAVE_CONF_NEXT_MASK))
			break;
	}

	return 0;
}

static ssize_t fsi_slave_sysfs_raw_read(struct file *file,
		struct kobject *kobj, struct bin_attribute *attr, char *buf,
		loff_t off, size_t count)
{
	struct fsi_slave *slave = to_fsi_slave(kobj_to_dev(kobj));
	size_t total_len, read_len;
	int rc;

	if (off < 0)
		return -EINVAL;

	if (off > 0xffffffff || count > 0xffffffff || off + count > 0xffffffff)
		return -EINVAL;

	for (total_len = 0; total_len < count; total_len += read_len) {
		read_len = min_t(size_t, count, 4);
		read_len -= off & 0x3;

		rc = fsi_slave_read(slave, off, buf + total_len, read_len);
		if (rc)
			return rc;

		off += read_len;
	}

	return count;
}

static ssize_t fsi_slave_sysfs_raw_write(struct file *file,
		struct kobject *kobj, struct bin_attribute *attr,
		char *buf, loff_t off, size_t count)
{
	struct fsi_slave *slave = to_fsi_slave(kobj_to_dev(kobj));
	size_t total_len, write_len;
	int rc;

	if (off < 0)
		return -EINVAL;

	if (off > 0xffffffff || count > 0xffffffff || off + count > 0xffffffff)
		return -EINVAL;

	for (total_len = 0; total_len < count; total_len += write_len) {
		write_len = min_t(size_t, count, 4);
		write_len -= off & 0x3;

		rc = fsi_slave_write(slave, off, buf + total_len, write_len);
		if (rc)
			return rc;

		off += write_len;
	}

	return count;
}

static const struct bin_attribute fsi_slave_raw_attr = {
	.attr = {
		.name = "raw",
		.mode = 0600,
	},
	.size = 0,
	.read = fsi_slave_sysfs_raw_read,
	.write = fsi_slave_sysfs_raw_write,
};

static ssize_t fsi_slave_sysfs_term_write(struct file *file,
		struct kobject *kobj, struct bin_attribute *attr,
		char *buf, loff_t off, size_t count)
{
	struct fsi_slave *slave = to_fsi_slave(kobj_to_dev(kobj));
	struct fsi_master *master = slave->master;

	if (!master->term)
		return -ENODEV;

	master->term(master, slave->link, slave->id);
	return count;
}

static const struct bin_attribute fsi_slave_term_attr = {
	.attr = {
		.name = "term",
		.mode = 0200,
	},
	.size = 0,
	.write = fsi_slave_sysfs_term_write,
};

/* Encode slave local bus echo delay */
static inline uint32_t fsi_smode_echodly(int x)
{
	return (x & FSI_SMODE_ED_MASK) << FSI_SMODE_ED_SHIFT;
}

/* Encode slave local bus send delay */
static inline uint32_t fsi_smode_senddly(int x)
{
	return (x & FSI_SMODE_SD_MASK) << FSI_SMODE_SD_SHIFT;
}

/* Encode slave local bus clock rate ratio */
static inline uint32_t fsi_smode_lbcrr(int x)
{
	return (x & FSI_SMODE_LBCRR_MASK) << FSI_SMODE_LBCRR_SHIFT;
}

/* Encode slave ID */
static inline uint32_t fsi_smode_sid(int x)
{
	return (x & FSI_SMODE_SID_MASK) << FSI_SMODE_SID_SHIFT;
}

static uint32_t fsi_slave_smode(int id)
{
	return FSI_SMODE_WSC | FSI_SMODE_ECRC
		| fsi_smode_sid(id)
		| fsi_smode_echodly(0xf) | fsi_smode_senddly(0xf)
		| fsi_smode_lbcrr(0x8);
}

static int fsi_slave_set_smode(struct fsi_master *master, int link, int id)
{
	uint32_t smode;

	/* set our smode register with the slave ID field to 0; this enables
	 * extended slave addressing
	 */
	smode = fsi_slave_smode(id);
	smode = cpu_to_be32(smode);

	return fsi_master_write(master, link, id, FSI_SLAVE_BASE + FSI_SMODE,
			&smode, sizeof(smode));
}

static void fsi_slave_release(struct device *dev)
{
	struct fsi_slave *slave = to_fsi_slave(dev);

	kfree(slave);
}

static int fsi_slave_init(struct fsi_master *master, int link, uint8_t id)
{
	uint32_t chip_id, llmode;
	struct fsi_slave *slave;
	uint8_t crc;
	int rc;

	/* Currently, we only support single slaves on a link, and use the
	 * full 23-bit address range
	 */
	if (id != 0)
		return -EINVAL;

	rc = fsi_master_read(master, link, id, 0, &chip_id, sizeof(chip_id));
	if (rc) {
		dev_dbg(&master->dev, "can't read slave %02x:%02x %d\n",
				link, id, rc);
		return -ENODEV;
	}
	chip_id = be32_to_cpu(chip_id);

	crc = crc4(0, chip_id, 32);
	if (crc) {
		dev_warn(&master->dev, "slave %02x:%02x invalid chip id CRC!\n",
				link, id);
		return -EIO;
	}

	dev_info(&master->dev, "fsi: found chip %08x at %02x:%02x:%02x\n",
			chip_id, master->idx, link, id);

	rc = fsi_slave_set_smode(master, link, id);
	if (rc) {
		dev_warn(&master->dev,
				"can't set smode on slave:%02x:%02x %d\n",
				link, id, rc);
		return -ENODEV;
	}

	/* If we're behind a master that doesn't provide a self-running bus
	 * clock, put the slave into async mode
	 */
	if (master->flags & FSI_MASTER_FLAG_SWCLOCK) {
		llmode = cpu_to_be32(FSI_LLMODE_ASYNC);
		rc = fsi_master_write(master, link, id,
				FSI_SLAVE_BASE + FSI_LLMODE,
				&llmode, sizeof(llmode));
		if (rc)
			dev_warn(&master->dev,
				"can't set llmode on slave:%02x:%02x %d\n",
				link, id, rc);
	}

	/* We can communicate with a slave; create the slave device and
	 * register.
	 */
	slave = kzalloc(sizeof(*slave), GFP_KERNEL);
	if (!slave)
		return -ENOMEM;

	slave->master = master;
	slave->dev.parent = &master->dev;
	slave->dev.release = fsi_slave_release;
	slave->link = link;
	slave->id = id;
	slave->size = FSI_SLAVE_SIZE_23b;

	dev_set_name(&slave->dev, "slave@%02x:%02x", link, id);
	rc = device_register(&slave->dev);
	if (rc < 0) {
		dev_warn(&master->dev, "failed to create slave device: %d\n",
				rc);
		put_device(&slave->dev);
		return rc;
	}

	rc = device_create_bin_file(&slave->dev, &fsi_slave_raw_attr);
	if (rc)
		dev_warn(&slave->dev, "failed to create raw attr: %d\n", rc);

	rc = device_create_bin_file(&slave->dev, &fsi_slave_term_attr);
	if (rc)
		dev_warn(&slave->dev, "failed to create term attr: %d\n", rc);

	rc = fsi_slave_scan(slave);
	if (rc)
		dev_dbg(&master->dev, "failed during slave scan with: %d\n",
				rc);

	return rc;
}

/* FSI master support */
static int fsi_check_access(uint32_t addr, size_t size)
{
	if (size != 1 && size != 2 && size != 4)
		return -EINVAL;

	if ((addr & 0x3) != (size & 0x3))
		return -EINVAL;

	return 0;
}

static int fsi_master_read(struct fsi_master *master, int link,
		uint8_t slave_id, uint32_t addr, void *val, size_t size)
{
	int rc;

	trace_fsi_master_read(master, link, slave_id, addr, size);

	rc = fsi_check_access(addr, size);
	if (!rc)
		rc = master->read(master, link, slave_id, addr, val, size);

	trace_fsi_master_rw_result(master, link, slave_id, addr, size,
			false, val, rc);

	return rc;
}

static int fsi_master_write(struct fsi_master *master, int link,
		uint8_t slave_id, uint32_t addr, const void *val, size_t size)
{
	int rc;

	trace_fsi_master_write(master, link, slave_id, addr, size, val);

	rc = fsi_check_access(addr, size);
	if (!rc)
		rc = master->write(master, link, slave_id, addr, val, size);

	trace_fsi_master_rw_result(master, link, slave_id, addr, size,
			true, val, rc);

	return rc;
}

static int fsi_master_link_enable(struct fsi_master *master, int link)
{
	if (master->link_enable)
		return master->link_enable(master, link);

	return 0;
}

/*
 * Issue a break command on this link
 */
static int fsi_master_break(struct fsi_master *master, int link)
{
	trace_fsi_master_break(master, link);

	if (master->send_break)
		return master->send_break(master, link);

	return 0;
}

static int fsi_master_scan(struct fsi_master *master)
{
	int link, rc;

	for (link = 0; link < master->n_links; link++) {
		rc = fsi_master_link_enable(master, link);
		if (rc) {
			dev_dbg(&master->dev,
				"enable link %d failed: %d\n", link, rc);
			continue;
		}
		rc = fsi_master_break(master, link);
		if (rc) {
			dev_dbg(&master->dev,
				"break to link %d failed: %d\n", link, rc);
			continue;
		}

		fsi_slave_init(master, link, 0);
	}

	return 0;
}

static int fsi_slave_remove_device(struct device *dev, void *arg)
{
	device_unregister(dev);
	return 0;
}

static int fsi_master_remove_slave(struct device *dev, void *arg)
{
	device_for_each_child(dev, NULL, fsi_slave_remove_device);
	device_unregister(dev);
	return 0;
}

static void fsi_master_unscan(struct fsi_master *master)
{
	device_for_each_child(&master->dev, NULL, fsi_master_remove_slave);
}

static ssize_t master_rescan_store(struct device *dev,
		struct device_attribute *attr, const char *buf, size_t count)
{
	struct fsi_master *master = to_fsi_master(dev);
	int rc;

	fsi_master_unscan(master);
	rc = fsi_master_scan(master);
	if (rc < 0)
		return rc;

	return count;
}

static DEVICE_ATTR(rescan, 0200, NULL, master_rescan_store);

static ssize_t master_break_store(struct device *dev,
		struct device_attribute *attr, const char *buf, size_t count)
{
	struct fsi_master *master = to_fsi_master(dev);

	fsi_master_break(master, 0);

	return count;
}

static DEVICE_ATTR(break, 0200, NULL, master_break_store);

int fsi_master_register(struct fsi_master *master)
{
	int rc;

	if (!master)
		return -EINVAL;

	master->idx = ida_simple_get(&master_ida, 0, INT_MAX, GFP_KERNEL);
	dev_set_name(&master->dev, "fsi%d", master->idx);

	rc = device_register(&master->dev);
	if (rc) {
		ida_simple_remove(&master_ida, master->idx);
		return rc;
	}

	rc = device_create_file(&master->dev, &dev_attr_rescan);
	if (rc) {
		device_unregister(&master->dev);
		ida_simple_remove(&master_ida, master->idx);
		return rc;
	}

	rc = device_create_file(&master->dev, &dev_attr_break);
	if (rc) {
		device_unregister(&master->dev);
		ida_simple_remove(&master_ida, master->idx);
		return rc;
	}

	fsi_master_scan(master);

	return 0;
}
EXPORT_SYMBOL_GPL(fsi_master_register);

void fsi_master_unregister(struct fsi_master *master)
{
	if (master->idx >= 0) {
		ida_simple_remove(&master_ida, master->idx);
		master->idx = -1;
	}

	fsi_master_unscan(master);
	device_unregister(&master->dev);
}
EXPORT_SYMBOL_GPL(fsi_master_unregister);

/* FSI core & Linux bus type definitions */

static int fsi_bus_match(struct device *dev, struct device_driver *drv)
{
	struct fsi_device *fsi_dev = to_fsi_dev(dev);
	struct fsi_driver *fsi_drv = to_fsi_drv(drv);
	const struct fsi_device_id *id;

	if (!fsi_drv->id_table)
		return 0;

	for (id = fsi_drv->id_table; id->engine_type; id++) {
		if (id->engine_type != fsi_dev->engine_type)
			continue;
		if (id->version == FSI_VERSION_ANY ||
				id->version == fsi_dev->version)
			return 1;
	}

	return 0;
}

int fsi_driver_register(struct fsi_driver *fsi_drv)
{
	if (!fsi_drv)
		return -EINVAL;
	if (!fsi_drv->id_table)
		return -EINVAL;

	return driver_register(&fsi_drv->drv);
}
EXPORT_SYMBOL_GPL(fsi_driver_register);

void fsi_driver_unregister(struct fsi_driver *fsi_drv)
{
	driver_unregister(&fsi_drv->drv);
}
EXPORT_SYMBOL_GPL(fsi_driver_unregister);

struct bus_type fsi_bus_type = {
	.name		= "fsi",
	.match		= fsi_bus_match,
};
EXPORT_SYMBOL_GPL(fsi_bus_type);

static int __init fsi_init(void)
{
	return bus_register(&fsi_bus_type);
}
postcore_initcall(fsi_init);

static void fsi_exit(void)
{
	bus_unregister(&fsi_bus_type);
}
module_exit(fsi_exit);
module_param(discard_errors, int, 0664);
MODULE_LICENSE("GPL");
MODULE_PARM_DESC(discard_errors, "Don't invoke error handling on bus accesses");