summaryrefslogtreecommitdiffstats
path: root/drivers/fsi/fsi-sbefifo.c
blob: f54df9ebc8b305bc057533a7ebf283ec43f7b6c2 (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
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) IBM Corporation 2017
 *
 * 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
 * MERGCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/device.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/fsi.h>
#include <linux/fsi-sbefifo.h>
#include <linux/kernel.h>
#include <linux/cdev.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/of_platform.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/delay.h>
#include <linux/uio.h>
#include <linux/vmalloc.h>
#include <linux/mm.h>

/*
 * The SBEFIFO is a pipe-like FSI device for communicating with
 * the self boot engine on POWER processors.
 */

#define DEVICE_NAME		"sbefifo"
#define FSI_ENGID_SBE		0x22

/*
 * Register layout
 */

/* Register banks */
#define SBEFIFO_UP		0x00		/* FSI -> Host */
#define SBEFIFO_DOWN		0x40		/* Host -> FSI */

/* Per-bank registers */
#define SBEFIFO_FIFO		0x00		/* The FIFO itself */
#define SBEFIFO_STS		0x04		/* Status register */
#define   SBEFIFO_STS_PARITY_ERR	0x20000000
#define   SBEFIFO_STS_RESET_REQ		0x02000000
#define   SBEFIFO_STS_GOT_EOT		0x00800000
#define   SBEFIFO_STS_MAX_XFER_LIMIT	0x00400000
#define   SBEFIFO_STS_FULL		0x00200000
#define   SBEFIFO_STS_EMPTY		0x00100000
#define   SBEFIFO_STS_ECNT_MASK		0x000f0000
#define   SBEFIFO_STS_ECNT_SHIFT	16
#define   SBEFIFO_STS_VALID_MASK	0x0000ff00
#define   SBEFIFO_STS_VALID_SHIFT	8
#define   SBEFIFO_STS_EOT_MASK		0x000000ff
#define   SBEFIFO_STS_EOT_SHIFT		0
#define SBEFIFO_EOT_RAISE	0x08		/* (Up only) Set End Of Transfer */
#define SBEFIFO_REQ_RESET	0x0C		/* (Up only) Reset Request */
#define SBEFIFO_PERFORM_RESET	0x10		/* (Down only) Perform Reset */
#define SBEFIFO_EOT_ACK		0x14		/* (Down only) Acknowledge EOT */
#define SBEFIFO_DOWN_MAX	0x18		/* (Down only) Max transfer */

/* CFAM GP Mailbox SelfBoot Message register */
#define CFAM_GP_MBOX_SBM_ADDR	0x2824	/* Converted 0x2809 */

#define CFAM_SBM_SBE_BOOTED		0x80000000
#define CFAM_SBM_SBE_ASYNC_FFDC		0x40000000
#define CFAM_SBM_SBE_STATE_MASK		0x00f00000
#define CFAM_SBM_SBE_STATE_SHIFT	20

enum sbe_state
{
	SBE_STATE_UNKNOWN = 0x0, // Unkown, initial state
	SBE_STATE_IPLING  = 0x1, // IPL'ing - autonomous mode (transient)
	SBE_STATE_ISTEP   = 0x2, // ISTEP - Running IPL by steps (transient)
	SBE_STATE_MPIPL   = 0x3, // MPIPL
	SBE_STATE_RUNTIME = 0x4, // SBE Runtime
	SBE_STATE_DMT     = 0x5, // Dead Man Timer State (transient)
	SBE_STATE_DUMP    = 0x6, // Dumping
	SBE_STATE_FAILURE = 0x7, // Internal SBE failure
	SBE_STATE_QUIESCE = 0x8, // Final state - needs SBE reset to get out
};

/* FIFO depth */
#define SBEFIFO_FIFO_DEPTH		8

/* Helpers */
#define sbefifo_empty(sts)	((sts) & SBEFIFO_STS_EMPTY)
#define sbefifo_full(sts)	((sts) & SBEFIFO_STS_FULL)
#define sbefifo_parity_err(sts)	((sts) & SBEFIFO_STS_PARITY_ERR)
#define sbefifo_populated(sts)	(((sts) & SBEFIFO_STS_ECNT_MASK) >> SBEFIFO_STS_ECNT_SHIFT)
#define sbefifo_vacant(sts)	(SBEFIFO_FIFO_DEPTH - sbefifo_populated(sts))
#define sbefifo_eot_set(sts)	(((sts) & SBEFIFO_STS_EOT_MASK) >> SBEFIFO_STS_EOT_SHIFT)

/* Reset request timeout in ms */
#define SBEFIFO_RESET_TIMEOUT		10000

/* Timeouts for commands in ms */
#define SBEFIFO_TIMEOUT_START_CMD	10000
#define SBEFIFO_TIMEOUT_IN_CMD		1000
#define SBEFIFO_TIMEOUT_START_RSP	10000
#define SBEFIFO_TIMEOUT_IN_RSP		1000

/* Other constants */
#define SBEFIFO_MAX_USER_CMD_LEN	(0x100000 + PAGE_SIZE)
#define SBEFIFO_RESET_MAGIC		0x52534554 /* "RSET" */

struct sbefifo {
	uint32_t		magic;
#define SBEFIFO_MAGIC		0x53424546 /* "SBEF" */
	struct fsi_device	*fsi_dev;
	struct device		dev;
	struct cdev		cdev;
	struct mutex		lock;
	bool			broken;
	bool			dead;
	bool			async_ffdc;
};

struct sbefifo_user {
	struct sbefifo		*sbefifo;
	struct mutex		file_lock;
	void			*cmd_page;
	void			*pending_cmd;
	size_t			pending_len;
};

static DEFINE_MUTEX(sbefifo_ffdc_mutex);


static void __sbefifo_dump_ffdc(struct device *dev, const __be32 *ffdc,
				size_t ffdc_sz, bool internal)
{
	int pack = 0;
#define FFDC_LSIZE	60
	static char ffdc_line[FFDC_LSIZE];
	char *p = ffdc_line;

	while (ffdc_sz) {
		u32 w0, w1, w2, i;
		if (ffdc_sz < 3) {
			dev_err(dev, "SBE invalid FFDC package size %zd\n", ffdc_sz);
			return;
		}
		w0 = be32_to_cpu(*(ffdc++));
		w1 = be32_to_cpu(*(ffdc++));
		w2 = be32_to_cpu(*(ffdc++));
		ffdc_sz -= 3;
		if ((w0 >> 16) != 0xFFDC) {
			dev_err(dev, "SBE invalid FFDC package signature %08x %08x %08x\n",
				w0, w1, w2);
			break;
		}
		w0 &= 0xffff;
		if (w0 > ffdc_sz) {
			dev_err(dev, "SBE FFDC package len %d words but only %zd remaining\n",
				w0, ffdc_sz);
			w0 = ffdc_sz;
			break;
		}
		if (internal) {
			dev_warn(dev, "+---- SBE FFDC package %d for async err -----+\n",
				 pack++);
		} else {
			dev_warn(dev, "+---- SBE FFDC package %d for cmd %02x:%02x -----+\n",
				 pack++, (w1 >> 8) & 0xff, w1 & 0xff);
		}
		dev_warn(dev, "| Response code: %08x                   |\n", w2);
		dev_warn(dev, "|-------------------------------------------|\n");
		for (i = 0; i < w0; i++) {
			if ((i & 3) == 0) {
				p = ffdc_line;
				p += sprintf(p, "| %04x:", i << 4);
			}
			p += sprintf(p, " %08x", be32_to_cpu(*(ffdc++)));
			ffdc_sz--;
			if ((i & 3) == 3 || i == (w0 - 1)) {
				while ((i & 3) < 3) {
					p += sprintf(p, "         ");
					i++;
				}
				dev_warn(dev, "%s |\n", ffdc_line);
			}
		}
		dev_warn(dev, "+-------------------------------------------+\n");
	}
}

static void sbefifo_dump_ffdc(struct device *dev, const __be32 *ffdc,
			      size_t ffdc_sz, bool internal)
{
	mutex_lock(&sbefifo_ffdc_mutex);
	__sbefifo_dump_ffdc(dev, ffdc, ffdc_sz, internal);
	mutex_unlock(&sbefifo_ffdc_mutex);
}

int sbefifo_parse_status(struct device *dev, u16 cmd, __be32 *response,
			 size_t resp_len, size_t *data_len)
{
	u32 dh, s0, s1;
	size_t ffdc_sz;

	if (resp_len < 3) {
		pr_debug("sbefifo: cmd %04x, response too small: %zd\n",
			 cmd, resp_len);
		return -ENXIO;
	}
	dh = be32_to_cpu(response[resp_len - 1]);
	if (dh > resp_len || dh < 3) {
		dev_err(dev, "SBE cmd %02x:%02x status offset out of range: %d/%zd\n",
			cmd >> 8, cmd & 0xff, dh, resp_len);
		return -ENXIO;
	}
	s0 = be32_to_cpu(response[resp_len - dh]);
	s1 = be32_to_cpu(response[resp_len - dh + 1]);
	if (((s0 >> 16) != 0xC0DE) || ((s0 & 0xffff) != cmd)) {
		dev_err(dev, "SBE cmd %02x:%02x, status signature invalid: 0x%08x 0x%08x\n",
			cmd >> 8, cmd & 0xff, s0, s1);
		return -ENXIO;
	}
	if (s1 != 0) {
		ffdc_sz = dh - 3;
		dev_warn(dev, "SBE error cmd %02x:%02x status=%04x:%04x\n",
			 cmd >> 8, cmd & 0xff, s1 >> 16, s1 & 0xffff);
		if (ffdc_sz)
			sbefifo_dump_ffdc(dev, &response[resp_len - dh + 2],
					  ffdc_sz, false);
	}
	if (data_len)
		*data_len = resp_len - dh;

	/*
	 * Primary status don't have the top bit set, so can't be confused with
	 * Linux negative error codes, so return the status word whole.
	 */
	return s1;
}
EXPORT_SYMBOL_GPL(sbefifo_parse_status);

static int sbefifo_regr(struct sbefifo *sbefifo, int reg, u32 *word)
{
	__be32 raw_word;
	int rc;

	rc = fsi_device_read(sbefifo->fsi_dev, reg, &raw_word,
			     sizeof(raw_word));
	if (rc)
		return rc;

	*word = be32_to_cpu(raw_word);

	return 0;
}

static int sbefifo_regw(struct sbefifo *sbefifo, int reg, u32 word)
{
	__be32 raw_word = cpu_to_be32(word);

	return fsi_device_write(sbefifo->fsi_dev, reg, &raw_word,
				sizeof(raw_word));
}

static int sbefifo_check_sbe_state(struct sbefifo *sbefifo)
{
	__be32 raw_word;
	u32 sbm;
	int rc;

	rc = fsi_slave_read(sbefifo->fsi_dev->slave, CFAM_GP_MBOX_SBM_ADDR,
			    &raw_word, sizeof(raw_word));
	if (rc)
		return rc;
	sbm = be32_to_cpu(raw_word);

	/* SBE booted at all ? */
	if (!(sbm & CFAM_SBM_SBE_BOOTED))
		return -ESHUTDOWN;

	/* Check its state */
	switch ((sbm & CFAM_SBM_SBE_STATE_MASK) >> CFAM_SBM_SBE_STATE_SHIFT) {
	case SBE_STATE_UNKNOWN:
		return -ESHUTDOWN;
	case SBE_STATE_DMT:
		return -EBUSY;
	case SBE_STATE_IPLING:
	case SBE_STATE_ISTEP:
	case SBE_STATE_MPIPL:
	case SBE_STATE_RUNTIME:
	case SBE_STATE_DUMP: /* Not sure about that one */
		break;
	case SBE_STATE_FAILURE:
	case SBE_STATE_QUIESCE:
		return -ESHUTDOWN;
	}

	/* Is there async FFDC available ? Remember it */
	if (sbm & CFAM_SBM_SBE_ASYNC_FFDC)
		sbefifo->async_ffdc = true;

	return 0;
}

/* Don't flip endianness of data to/from FIFO, just pass through. */
static int sbefifo_down_read(struct sbefifo *sbefifo, __be32 *word)
{
	return fsi_device_read(sbefifo->fsi_dev, SBEFIFO_DOWN, word,
			       sizeof(*word));
}

static int sbefifo_up_write(struct sbefifo *sbefifo, __be32 word)
{
	return fsi_device_write(sbefifo->fsi_dev, SBEFIFO_UP, &word,
				sizeof(word));
}

static int sbefifo_request_reset(struct sbefifo *sbefifo)
{
	struct device *dev = &sbefifo->fsi_dev->dev;
	u32 status, timeout;
	int rc;

	dev_dbg(dev, "Requesting FIFO reset\n");

	/* Mark broken first, will be cleared if reset succeeds */
	sbefifo->broken = true;

	/* Send reset request */
	rc = sbefifo_regw(sbefifo, SBEFIFO_UP | SBEFIFO_REQ_RESET, 1);
	if (rc) {
		dev_err(dev, "Sending reset request failed, rc=%d\n", rc);
		return rc;
	}

	/* Wait for it to complete */
	for (timeout = 0; timeout < SBEFIFO_RESET_TIMEOUT; timeout++) {
		rc = sbefifo_regr(sbefifo, SBEFIFO_UP | SBEFIFO_STS, &status);
		if (rc) {
			dev_err(dev, "Failed to read UP fifo status during reset"
				" , rc=%d\n", rc);
			return rc;
		}

		if (!(status & SBEFIFO_STS_RESET_REQ)) {
			dev_dbg(dev, "FIFO reset done\n");
			sbefifo->broken = false;
			return 0;
		}

		msleep(1);
	}
	dev_err(dev, "FIFO reset timed out\n");

	return -ETIMEDOUT;
}

static int sbefifo_cleanup_hw(struct sbefifo *sbefifo)
{
	struct device *dev = &sbefifo->fsi_dev->dev;
	u32 up_status, down_status;
	bool need_reset = false;
	int rc;

	rc = sbefifo_check_sbe_state(sbefifo);
	if (rc) {
		dev_dbg(dev, "SBE state=%d\n", rc);
		return rc;
	}

	/* If broken, we don't need to look at status, go straight to reset */
	if (sbefifo->broken)
		goto do_reset;

	rc = sbefifo_regr(sbefifo, SBEFIFO_UP | SBEFIFO_STS, &up_status);
	if (rc) {
		dev_err(dev, "Cleanup: Reading UP status failed, rc=%d\n", rc);

		/* Will try reset again on next attempt at using it */
		sbefifo->broken = true;
		return rc;
	}

	rc = sbefifo_regr(sbefifo, SBEFIFO_DOWN | SBEFIFO_STS, &down_status);
	if (rc) {
		dev_err(dev, "Cleanup: Reading DOWN status failed, rc=%d\n", rc);

		/* Will try reset again on next attempt at using it */
		sbefifo->broken = true;
		return rc;
	}

	/* The FIFO already contains a reset request from the SBE ? */
	if (down_status & SBEFIFO_STS_RESET_REQ) {
		dev_info(dev, "Cleanup: FIFO reset request set, resetting\n");
		rc = sbefifo_regw(sbefifo, SBEFIFO_UP, SBEFIFO_PERFORM_RESET);
		if (rc) {
			sbefifo->broken = true;
			dev_err(dev, "Cleanup: Reset reg write failed, rc=%d\n", rc);
			return rc;
		}
		sbefifo->broken = false;
		return 0;
	}

	/* Parity error on either FIFO ? */
	if ((up_status | down_status) & SBEFIFO_STS_PARITY_ERR)
		need_reset = true;

	/* Either FIFO not empty ? */
	if (!((up_status & down_status) & SBEFIFO_STS_EMPTY))
		need_reset = true;

	if (!need_reset)
		return 0;

	dev_info(dev, "Cleanup: FIFO not clean (up=0x%08x down=0x%08x)\n",
		 up_status, down_status);

 do_reset:

	/* Mark broken, will be cleared if/when reset succeeds */
	return sbefifo_request_reset(sbefifo);
}

static int sbefifo_wait(struct sbefifo *sbefifo, bool up,
			u32 *status, unsigned long timeout)
{
	struct device *dev = &sbefifo->fsi_dev->dev;
	unsigned long end_time;
	bool ready = false;
	u32 addr, sts = 0;
	int rc;

	dev_vdbg(dev, "Wait on %s fifo...\n", up ? "up" : "down");

	addr = (up ? SBEFIFO_UP : SBEFIFO_DOWN) | SBEFIFO_STS;

	end_time = jiffies + timeout;
	while (!time_after(jiffies, end_time)) {
		cond_resched();
		rc = sbefifo_regr(sbefifo, addr, &sts);
		if (rc < 0) {
			dev_err(dev, "FSI error %d reading status register\n", rc);
			return rc;
		}
		if (!up && sbefifo_parity_err(sts)) {
			dev_err(dev, "Parity error in DOWN FIFO\n");
			return -ENXIO;
		}
		ready = !(up ? sbefifo_full(sts) : sbefifo_empty(sts));
		if (ready)
			break;
	}
	if (!ready) {
		dev_err(dev, "%s FIFO Timeout ! status=%08x\n", up ? "UP" : "DOWN", sts);
		return -ETIMEDOUT;
	}
	dev_vdbg(dev, "End of wait status: %08x\n", sts);

	*status = sts;

	return 0;
}

static int sbefifo_send_command(struct sbefifo *sbefifo,
				const __be32 *command, size_t cmd_len)
{
	struct device *dev = &sbefifo->fsi_dev->dev;
	size_t len, chunk, vacant = 0, remaining = cmd_len;
	unsigned long timeout;
	u32 status;
	int rc;

	dev_vdbg(dev, "sending command (%zd words, cmd=%04x)\n",
		 cmd_len, be32_to_cpu(command[1]));

	/* As long as there's something to send */
	timeout = msecs_to_jiffies(SBEFIFO_TIMEOUT_START_CMD);
	while (remaining) {
		/* Wait for room in the FIFO */
		rc = sbefifo_wait(sbefifo, true, &status, timeout);
		if (rc < 0)
			return rc;
		timeout = msecs_to_jiffies(SBEFIFO_TIMEOUT_IN_CMD);

		vacant = sbefifo_vacant(status);
		len = chunk = min(vacant, remaining);

		dev_vdbg(dev, "  status=%08x vacant=%zd chunk=%zd\n",
			 status, vacant, chunk);

		/* Write as much as we can */
		while (len--) {
			rc = sbefifo_up_write(sbefifo, *(command++));
			if (rc) {
				dev_err(dev, "FSI error %d writing UP FIFO\n", rc);
				return rc;
			}
		}
		remaining -= chunk;
		vacant -= chunk;
	}

	/* If there's no room left, wait for some to write EOT */
	if (!vacant) {
		rc = sbefifo_wait(sbefifo, true, &status, timeout);
		if (rc)
			return rc;
	}

	/* Send an EOT */
	rc = sbefifo_regw(sbefifo, SBEFIFO_UP | SBEFIFO_EOT_RAISE, 0);
	if (rc)
		dev_err(dev, "FSI error %d writing EOT\n", rc);
	return rc;
}

static int sbefifo_read_response(struct sbefifo *sbefifo, struct iov_iter *response)
{
	struct device *dev = &sbefifo->fsi_dev->dev;
	u32 status, eot_set;
	unsigned long timeout;
	bool overflow = false;
	__be32 data;
	size_t len;
	int rc;

	dev_vdbg(dev, "reading response, buflen = %zd\n", iov_iter_count(response));

	timeout = msecs_to_jiffies(SBEFIFO_TIMEOUT_START_RSP);
	for (;;) {
		/* Grab FIFO status (this will handle parity errors) */
		rc = sbefifo_wait(sbefifo, false, &status, timeout);
		if (rc < 0)
			return rc;
		timeout = msecs_to_jiffies(SBEFIFO_TIMEOUT_IN_RSP);

		/* Decode status */
		len = sbefifo_populated(status);
		eot_set = sbefifo_eot_set(status);

		dev_vdbg(dev, "  chunk size %zd eot_set=0x%x\n", len, eot_set);

		/* Go through the chunk */
		while(len--) {
			/* Read the data */
			rc = sbefifo_down_read(sbefifo, &data);
			if (rc < 0)
				return rc;

			/* Was it an EOT ? */
			if (eot_set & 0x80) {
				/*
				 * There should be nothing else in the FIFO,
				 * if there is, mark broken, this will force
				 * a reset on next use, but don't fail the
				 * command.
				 */
				if (len) {
					dev_warn(dev, "FIFO read hit"
						 " EOT with still %zd data\n",
						 len);
					sbefifo->broken = true;
				}

				/* We are done */
				rc = sbefifo_regw(sbefifo,
						  SBEFIFO_DOWN | SBEFIFO_EOT_ACK, 0);

				/*
				 * If that write fail, still complete the request but mark
				 * the fifo as broken for subsequent reset (not much else
				 * we can do here).
				 */
				if (rc) {
					dev_err(dev, "FSI error %d ack'ing EOT\n", rc);
					sbefifo->broken = true;
				}

				/* Tell whether we overflowed */
				return overflow ? -EOVERFLOW : 0;
			}

			/* Store it if there is room */
			if (iov_iter_count(response) >= sizeof(__be32)) {
				if (copy_to_iter(&data, sizeof(__be32), response) < sizeof(__be32))
					return -EFAULT;
			} else {
				dev_vdbg(dev, "Response overflowed !\n");

				overflow = true;
			}

			/* Next EOT bit */
			eot_set <<= 1;
		}
	}
	/* Shouldn't happen */
	return -EIO;
}

static int sbefifo_do_command(struct sbefifo *sbefifo,
			      const __be32 *command, size_t cmd_len,
			      struct iov_iter *response)
{
	/* Try sending the command */
	int rc = sbefifo_send_command(sbefifo, command, cmd_len);
	if (rc)
		return rc;

	/* Now, get the response */
	return sbefifo_read_response(sbefifo, response);
}

static void sbefifo_collect_async_ffdc(struct sbefifo *sbefifo)
{
	struct device *dev = &sbefifo->fsi_dev->dev;
        struct iov_iter ffdc_iter;
        struct kvec ffdc_iov;
	__be32 *ffdc;
	size_t ffdc_sz;
	__be32 cmd[2];
	int rc;

	sbefifo->async_ffdc = false;
	ffdc = vmalloc(SBEFIFO_MAX_FFDC_SIZE);
	if (!ffdc) {
		dev_err(dev, "Failed to allocate SBE FFDC buffer\n");
		return;
	}
        ffdc_iov.iov_base = ffdc;
	ffdc_iov.iov_len = SBEFIFO_MAX_FFDC_SIZE;
        iov_iter_kvec(&ffdc_iter, WRITE, &ffdc_iov, 1, SBEFIFO_MAX_FFDC_SIZE);
	cmd[0] = cpu_to_be32(2);
	cmd[1] = cpu_to_be32(SBEFIFO_CMD_GET_SBE_FFDC);
	rc = sbefifo_do_command(sbefifo, cmd, 2, &ffdc_iter);
	if (rc != 0) {
		dev_err(dev, "Error %d retrieving SBE FFDC\n", rc);
		goto bail;
	}
	ffdc_sz = SBEFIFO_MAX_FFDC_SIZE - iov_iter_count(&ffdc_iter);
	ffdc_sz /= sizeof(__be32);
	rc = sbefifo_parse_status(dev, SBEFIFO_CMD_GET_SBE_FFDC, ffdc,
				  ffdc_sz, &ffdc_sz);
	if (rc != 0) {
		dev_err(dev, "Error %d decoding SBE FFDC\n", rc);
		goto bail;
	}
	if (ffdc_sz > 0)
		sbefifo_dump_ffdc(dev, ffdc, ffdc_sz, true);
 bail:
	vfree(ffdc);

}

static int __sbefifo_submit(struct sbefifo *sbefifo,
			    const __be32 *command, size_t cmd_len,
			    struct iov_iter *response)
{
	struct device *dev = &sbefifo->fsi_dev->dev;
	int rc;

	if (sbefifo->dead)
		return -ENODEV;

	if (cmd_len < 2 || be32_to_cpu(command[0]) != cmd_len) {
		dev_vdbg(dev, "Invalid command len %zd (header: %d)\n",
			 cmd_len, be32_to_cpu(command[0]));
		return -EINVAL;
	}

	/* First ensure the HW is in a clean state */
	rc = sbefifo_cleanup_hw(sbefifo);
	if (rc)
		return rc;

	/* Look for async FFDC first if any */
	if (sbefifo->async_ffdc)
		sbefifo_collect_async_ffdc(sbefifo);

	rc = sbefifo_do_command(sbefifo, command, cmd_len, response);
	if (rc != 0 && rc != -EOVERFLOW)
		goto fail;
	return rc;
 fail:
	/*
	 * On failure, attempt a reset. Ignore the result, it will mark
	 * the fifo broken if the reset fails
	 */
        sbefifo_request_reset(sbefifo);

	/* Return original error */
	return rc;
}

/**
 * sbefifo_submit() - Submit and SBE fifo command and receive response
 * @dev: The sbefifo device
 * @command: The raw command data
 * @cmd_len: The command size (in 32-bit words)
 * @response: The output response buffer
 * @resp_len: In: Response buffer size, Out: Response size
 *
 * This will perform the entire operation. If the reponse buffer
 * overflows, returns -EOVERFLOW
 */
int sbefifo_submit(struct device *dev, const __be32 *command, size_t cmd_len,
		   __be32 *response, size_t *resp_len)
{
	struct sbefifo *sbefifo;
        struct iov_iter resp_iter;
        struct kvec resp_iov;
	size_t rbytes;
	int rc;

	if (!dev)
		return -ENODEV;
	sbefifo = dev_get_drvdata(dev);
	if (!sbefifo)
		return -ENODEV;
	if (WARN_ON_ONCE(sbefifo->magic != SBEFIFO_MAGIC))
		return -ENODEV;
	if (!resp_len || !command || !response)
		return -EINVAL;

	/* Prepare iov iterator */
	rbytes = (*resp_len) * sizeof(__be32);
	resp_iov.iov_base = response;
	resp_iov.iov_len = rbytes;
        iov_iter_kvec(&resp_iter, WRITE, &resp_iov, 1, rbytes);

	/* Perform the command */
	mutex_lock(&sbefifo->lock);
	rc = __sbefifo_submit(sbefifo, command, cmd_len, &resp_iter);
	mutex_unlock(&sbefifo->lock);

	/* Extract the response length */
	rbytes -= iov_iter_count(&resp_iter);
	*resp_len = rbytes / sizeof(__be32);

	return rc;
}
EXPORT_SYMBOL_GPL(sbefifo_submit);

/*
 * Char device interface
 */

static void sbefifo_release_command(struct sbefifo_user *user)
{
	if (is_vmalloc_addr(user->pending_cmd))
		vfree(user->pending_cmd);
	user->pending_cmd = NULL;
	user->pending_len = 0;
}

static int sbefifo_user_open(struct inode *inode, struct file *file)
{
	struct sbefifo *sbefifo = container_of(inode->i_cdev, struct sbefifo, cdev);
	struct sbefifo_user *user;

	user = kzalloc(sizeof(struct sbefifo_user), GFP_KERNEL);
	if (!user)
		return -ENOMEM;

	file->private_data = user;
	user->sbefifo = sbefifo;
	user->cmd_page = (void *)__get_free_page(GFP_KERNEL);
	if (!user->cmd_page) {
		kfree(user);
		return -ENOMEM;
	}
	mutex_init(&user->file_lock);

	return 0;
}

static ssize_t sbefifo_user_read(struct file *file, char __user *buf,
				 size_t len, loff_t *offset)
{
	struct sbefifo_user *user = file->private_data;
	struct sbefifo *sbefifo;
	struct iov_iter resp_iter;
        struct iovec resp_iov;
	size_t cmd_len;
	int rc;

	if (!user)
		return -EINVAL;
	sbefifo = user->sbefifo;
	if (len & 3)
		return -EINVAL;

	mutex_lock(&user->file_lock);

	/* Cronus relies on -EAGAIN after a short read */
	if (user->pending_len == 0) {
		rc = -EAGAIN;
		goto bail;
	}
	if (user->pending_len < 8) {
		rc = -EINVAL;
		goto bail;
	}
	cmd_len = user->pending_len >> 2;

	/* Prepare iov iterator */
	resp_iov.iov_base = buf;
	resp_iov.iov_len = len;
	iov_iter_init(&resp_iter, WRITE, &resp_iov, 1, len);

	/* Perform the command */
	mutex_lock(&sbefifo->lock);
	rc = __sbefifo_submit(sbefifo, user->pending_cmd, cmd_len, &resp_iter);
	mutex_unlock(&sbefifo->lock);
	if (rc < 0)
		goto bail;

	/* Extract the response length */
	rc = len - iov_iter_count(&resp_iter);
 bail:
	sbefifo_release_command(user);
	mutex_unlock(&user->file_lock);
	return rc;
}

static ssize_t sbefifo_user_write(struct file *file, const char __user *buf,
				  size_t len, loff_t *offset)
{
	struct sbefifo_user *user = file->private_data;
	struct sbefifo *sbefifo;
	int rc = len;

	if (!user)
		return -EINVAL;
	sbefifo = user->sbefifo;
	if (len > SBEFIFO_MAX_USER_CMD_LEN)
		return -EINVAL;
	if (len & 3)
		return -EINVAL;

	mutex_lock(&user->file_lock);

	/* Can we use the pre-allocate buffer ? If not, allocate */
	if (len <= PAGE_SIZE)
		user->pending_cmd = user->cmd_page;
	else
		user->pending_cmd = vmalloc(len);
	if (!user->pending_cmd) {
		rc = -ENOMEM;
		goto bail;
	}

	/* Copy the command into the staging buffer */
	if (copy_from_user(user->pending_cmd, buf, len)) {
		rc = -EFAULT;
		goto bail;
	}

	/* Check for the magic reset command */
	if (len == 4 && be32_to_cpu(*(__be32 *)user->pending_cmd) ==
	    SBEFIFO_RESET_MAGIC)  {

		/* Clear out any pending command */
		user->pending_len = 0;

		/* Trigger reset request */
		mutex_lock(&sbefifo->lock);
		rc = sbefifo_request_reset(user->sbefifo);
		mutex_unlock(&sbefifo->lock);
		if (rc == 0)
			rc = 4;
		goto bail;
	}

	/* Update the staging buffer size */
	user->pending_len = len;
 bail:
	if (!user->pending_len)
		sbefifo_release_command(user);

	mutex_unlock(&user->file_lock);

	/* And that's it, we'll issue the command on a read */
	return rc;
}

static int sbefifo_user_release(struct inode *inode, struct file *file)
{
	struct sbefifo_user *user = file->private_data;

	if (!user)
		return -EINVAL;

	sbefifo_release_command(user);
	free_page((unsigned long)user->cmd_page);
	kfree(user);

	return 0;
}

static const struct file_operations sbefifo_fops = {
	.owner		= THIS_MODULE,
	.open		= sbefifo_user_open,
	.read		= sbefifo_user_read,
	.write		= sbefifo_user_write,
	.release	= sbefifo_user_release,
};

static void sbefifo_free(struct device *dev)
{
	struct sbefifo *sbefifo = container_of(dev, struct sbefifo, dev);

	put_device(&sbefifo->fsi_dev->dev);
	kfree(sbefifo);
}

/*
 * Probe/remove
 */

static int sbefifo_probe(struct device *dev)
{
	struct fsi_device *fsi_dev = to_fsi_dev(dev);
	struct sbefifo *sbefifo;
	struct device_node *np;
	struct platform_device *child;
	char child_name[32];
	int rc, didx, child_idx = 0;

	dev_dbg(dev, "Found sbefifo device\n");

	sbefifo = kzalloc(sizeof(*sbefifo), GFP_KERNEL);
	if (!sbefifo)
		return -ENOMEM;

	/* Grab a reference to the device (parent of our cdev), we'll drop it later */
	if (!get_device(dev)) {
		kfree(sbefifo);
		return -ENODEV;
	}

	sbefifo->magic = SBEFIFO_MAGIC;
	sbefifo->fsi_dev = fsi_dev;
	dev_set_drvdata(dev, sbefifo);
	mutex_init(&sbefifo->lock);

	/*
	 * Try cleaning up the FIFO. If this fails, we still register the
	 * driver and will try cleaning things up again on the next access.
	 */
	rc = sbefifo_cleanup_hw(sbefifo);
	if (rc && rc != -ESHUTDOWN)
		dev_err(dev, "Initial HW cleanup failed, will retry later\n");

	/* Create chardev for userspace access */
	sbefifo->dev.type = &fsi_cdev_type;
	sbefifo->dev.parent = dev;
	sbefifo->dev.release = sbefifo_free;
	device_initialize(&sbefifo->dev);

	/* Allocate a minor in the FSI space */
	rc = fsi_get_new_minor(fsi_dev, fsi_dev_sbefifo, &sbefifo->dev.devt, &didx);
	if (rc)
		goto err;

	dev_set_name(&sbefifo->dev, "sbefifo%d", didx);
	cdev_init(&sbefifo->cdev, &sbefifo_fops);
	rc = cdev_device_add(&sbefifo->cdev, &sbefifo->dev);
	if (rc) {
		dev_err(dev, "Error %d creating char device %s\n",
			rc, dev_name(&sbefifo->dev));
		goto err_free_minor;
	}

	/* Create platform devs for dts child nodes (occ, etc) */
	for_each_available_child_of_node(dev->of_node, np) {
		snprintf(child_name, sizeof(child_name), "%s-dev%d",
			 dev_name(&sbefifo->dev), child_idx++);
		child = of_platform_device_create(np, child_name, dev);
		if (!child)
			dev_warn(dev, "failed to create child %s dev\n",
				 child_name);
	}

	return 0;
 err_free_minor:
	fsi_free_minor(sbefifo->dev.devt);
 err:
	put_device(&sbefifo->dev);
	return rc;
}

static int sbefifo_unregister_child(struct device *dev, void *data)
{
	struct platform_device *child = to_platform_device(dev);

	of_device_unregister(child);
	if (dev->of_node)
		of_node_clear_flag(dev->of_node, OF_POPULATED);

	return 0;
}

static int sbefifo_remove(struct device *dev)
{
	struct sbefifo *sbefifo = dev_get_drvdata(dev);

	dev_dbg(dev, "Removing sbefifo device...\n");

	mutex_lock(&sbefifo->lock);
	sbefifo->dead = true;
	mutex_unlock(&sbefifo->lock);

	cdev_device_del(&sbefifo->cdev, &sbefifo->dev);
	fsi_free_minor(sbefifo->dev.devt);
	device_for_each_child(dev, NULL, sbefifo_unregister_child);
	put_device(&sbefifo->dev);

	return 0;
}

static struct fsi_device_id sbefifo_ids[] = {
	{
		.engine_type = FSI_ENGID_SBE,
		.version = FSI_VERSION_ANY,
	},
	{ 0 }
};

static struct fsi_driver sbefifo_drv = {
	.id_table = sbefifo_ids,
	.drv = {
		.name = DEVICE_NAME,
		.bus = &fsi_bus_type,
		.probe = sbefifo_probe,
		.remove = sbefifo_remove,
	}
};

static int sbefifo_init(void)
{
	return fsi_driver_register(&sbefifo_drv);
}

static void sbefifo_exit(void)
{
	fsi_driver_unregister(&sbefifo_drv);
}

module_init(sbefifo_init);
module_exit(sbefifo_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Brad Bishop <bradleyb@fuzziesquirrel.com>");
MODULE_AUTHOR("Eddie James <eajames@linux.vnet.ibm.com>");
MODULE_AUTHOR("Andrew Jeffery <andrew@aj.id.au>");
MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
MODULE_DESCRIPTION("Linux device interface to the POWER Self Boot Engine");