summaryrefslogtreecommitdiff
path: root/drivers/tty/vcc.c
blob: 9ffd42e333b83f407b213d407d6f23094711adee (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
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
// SPDX-License-Identifier: GPL-2.0
/* vcc.c: sun4v virtual channel concentrator
 *
 * Copyright (C) 2017 Oracle. All rights reserved.
 */

#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/sysfs.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <asm/vio.h>
#include <asm/ldc.h>

#define DRV_MODULE_NAME		"vcc"
#define DRV_MODULE_VERSION	"1.1"
#define DRV_MODULE_RELDATE	"July 1, 2017"

static char version[] =
	DRV_MODULE_NAME ".c:v" DRV_MODULE_VERSION " (" DRV_MODULE_RELDATE ")";

MODULE_DESCRIPTION("Sun LDOM virtual console concentrator driver");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_MODULE_VERSION);

struct vcc_port {
	struct vio_driver_state vio;

	spinlock_t lock;
	char *domain;
	struct tty_struct *tty;	/* only populated while dev is open */
	unsigned long index;	/* index into the vcc_table */

	u64 refcnt;
	bool excl_locked;

	bool removed;

	/* This buffer is required to support the tty write_room interface
	 * and guarantee that any characters that the driver accepts will
	 * be eventually sent, either immediately or later.
	 */
	int chars_in_buffer;
	struct vio_vcc buffer;

	struct timer_list rx_timer;
	struct timer_list tx_timer;
};

/* Microseconds that thread will delay waiting for a vcc port ref */
#define VCC_REF_DELAY		100

#define VCC_MAX_PORTS		1024
#define VCC_MINOR_START		0	/* must be zero */
#define VCC_BUFF_LEN		VIO_VCC_MTU_SIZE

#define VCC_CTL_BREAK		-1
#define VCC_CTL_HUP		-2

static const char vcc_driver_name[] = "vcc";
static const char vcc_device_node[] = "vcc";
static struct tty_driver *vcc_tty_driver;

static struct vcc_port *vcc_table[VCC_MAX_PORTS];
static DEFINE_SPINLOCK(vcc_table_lock);

int vcc_dbg;
int vcc_dbg_ldc;
int vcc_dbg_vio;

module_param(vcc_dbg, uint, 0664);
module_param(vcc_dbg_ldc, uint, 0664);
module_param(vcc_dbg_vio, uint, 0664);

#define VCC_DBG_DRV	0x1
#define VCC_DBG_LDC	0x2
#define VCC_DBG_PKT	0x4

#define vccdbg(f, a...)						\
	do {							\
		if (vcc_dbg & VCC_DBG_DRV)			\
			pr_info(f, ## a);			\
	} while (0)						\

#define vccdbgl(l)						\
	do {							\
		if (vcc_dbg & VCC_DBG_LDC)			\
			ldc_print(l);				\
	} while (0)						\

#define vccdbgp(pkt)						\
	do {							\
		if (vcc_dbg & VCC_DBG_PKT) {			\
			int i;					\
			for (i = 0; i < pkt.tag.stype; i++)	\
				pr_info("[%c]", pkt.data[i]);	\
		}						\
	} while (0)						\

/* Note: Be careful when adding flags to this line discipline.  Don't
 * add anything that will cause echoing or we'll go into recursive
 * loop echoing chars back and forth with the console drivers.
 */
static const struct ktermios vcc_tty_termios = {
	.c_iflag = IGNBRK | IGNPAR,
	.c_oflag = OPOST,
	.c_cflag = B38400 | CS8 | CREAD | HUPCL,
	.c_cc = INIT_C_CC,
	.c_ispeed = 38400,
	.c_ospeed = 38400
};

/**
 * vcc_table_add() - Add VCC port to the VCC table
 * @port: pointer to the VCC port
 *
 * Return: index of the port in the VCC table on success,
 *	   -1 on failure
 */
static int vcc_table_add(struct vcc_port *port)
{
	unsigned long flags;
	int i;

	spin_lock_irqsave(&vcc_table_lock, flags);
	for (i = VCC_MINOR_START; i < VCC_MAX_PORTS; i++) {
		if (!vcc_table[i]) {
			vcc_table[i] = port;
			break;
		}
	}
	spin_unlock_irqrestore(&vcc_table_lock, flags);

	if (i < VCC_MAX_PORTS)
		return i;
	else
		return -1;
}

/**
 * vcc_table_remove() - Removes a VCC port from the VCC table
 * @index: Index into the VCC table
 */
static void vcc_table_remove(unsigned long index)
{
	unsigned long flags;

	if (WARN_ON(index >= VCC_MAX_PORTS))
		return;

	spin_lock_irqsave(&vcc_table_lock, flags);
	vcc_table[index] = NULL;
	spin_unlock_irqrestore(&vcc_table_lock, flags);
}

/**
 * vcc_get() - Gets a reference to VCC port
 * @index: Index into the VCC table
 * @excl: Indicates if an exclusive access is requested
 *
 * Return: reference to the VCC port, if found
 *	   NULL, if port not found
 */
static struct vcc_port *vcc_get(unsigned long index, bool excl)
{
	struct vcc_port *port;
	unsigned long flags;

try_again:
	spin_lock_irqsave(&vcc_table_lock, flags);

	port = vcc_table[index];
	if (!port) {
		spin_unlock_irqrestore(&vcc_table_lock, flags);
		return NULL;
	}

	if (!excl) {
		if (port->excl_locked) {
			spin_unlock_irqrestore(&vcc_table_lock, flags);
			udelay(VCC_REF_DELAY);
			goto try_again;
		}
		port->refcnt++;
		spin_unlock_irqrestore(&vcc_table_lock, flags);
		return port;
	}

	if (port->refcnt) {
		spin_unlock_irqrestore(&vcc_table_lock, flags);
		/* Threads wanting exclusive access will wait half the time,
		 * probably giving them higher priority in the case of
		 * multiple waiters.
		 */
		udelay(VCC_REF_DELAY/2);
		goto try_again;
	}

	port->refcnt++;
	port->excl_locked = true;
	spin_unlock_irqrestore(&vcc_table_lock, flags);

	return port;
}

/**
 * vcc_put() - Returns a reference to VCC port
 * @port: pointer to VCC port
 * @excl: Indicates if the returned reference is an exclusive reference
 *
 * Note: It's the caller's responsibility to ensure the correct value
 *	 for the excl flag
 */
static void vcc_put(struct vcc_port *port, bool excl)
{
	unsigned long flags;

	if (!port)
		return;

	spin_lock_irqsave(&vcc_table_lock, flags);

	/* check if caller attempted to put with the wrong flags */
	if (WARN_ON((excl && !port->excl_locked) ||
		    (!excl && port->excl_locked)))
		goto done;

	port->refcnt--;

	if (excl)
		port->excl_locked = false;

done:
	spin_unlock_irqrestore(&vcc_table_lock, flags);
}

/**
 * vcc_get_ne() - Get a non-exclusive reference to VCC port
 * @index: Index into the VCC table
 *
 * Gets a non-exclusive reference to VCC port, if it's not removed
 *
 * Return: pointer to the VCC port, if found
 *	   NULL, if port not found
 */
static struct vcc_port *vcc_get_ne(unsigned long index)
{
	struct vcc_port *port;

	port = vcc_get(index, false);

	if (port && port->removed) {
		vcc_put(port, false);
		return NULL;
	}

	return port;
}

static void vcc_kick_rx(struct vcc_port *port)
{
	struct vio_driver_state *vio = &port->vio;

	assert_spin_locked(&port->lock);

	if (!timer_pending(&port->rx_timer) && !port->removed) {
		disable_irq_nosync(vio->vdev->rx_irq);
		port->rx_timer.expires = (jiffies + 1);
		add_timer(&port->rx_timer);
	}
}

static void vcc_kick_tx(struct vcc_port *port)
{
	assert_spin_locked(&port->lock);

	if (!timer_pending(&port->tx_timer) && !port->removed) {
		port->tx_timer.expires = (jiffies + 1);
		add_timer(&port->tx_timer);
	}
}

static int vcc_rx_check(struct tty_struct *tty, int size)
{
	if (WARN_ON(!tty || !tty->port))
		return 1;

	/* tty_buffer_request_room won't sleep because it uses
	 * GFP_ATOMIC flag to allocate buffer
	 */
	if (test_bit(TTY_THROTTLED, &tty->flags) ||
	    (tty_buffer_request_room(tty->port, VCC_BUFF_LEN) < VCC_BUFF_LEN))
		return 0;

	return 1;
}

static int vcc_rx(struct tty_struct *tty, char *buf, int size)
{
	int len = 0;

	if (WARN_ON(!tty || !tty->port))
		return len;

	len = tty_insert_flip_string(tty->port, buf, size);
	if (len)
		tty_flip_buffer_push(tty->port);

	return len;
}

static int vcc_ldc_read(struct vcc_port *port)
{
	struct vio_driver_state *vio = &port->vio;
	struct tty_struct *tty;
	struct vio_vcc pkt;
	int rv = 0;

	tty = port->tty;
	if (!tty) {
		rv = ldc_rx_reset(vio->lp);
		vccdbg("VCC: reset rx q: rv=%d\n", rv);
		goto done;
	}

	/* Read as long as LDC has incoming data. */
	while (1) {
		if (!vcc_rx_check(tty, VIO_VCC_MTU_SIZE)) {
			vcc_kick_rx(port);
			break;
		}

		vccdbgl(vio->lp);

		rv = ldc_read(vio->lp, &pkt, sizeof(pkt));
		if (rv <= 0)
			break;

		vccdbg("VCC: ldc_read()=%d\n", rv);
		vccdbg("TAG [%02x:%02x:%04x:%08x]\n",
		       pkt.tag.type, pkt.tag.stype,
		       pkt.tag.stype_env, pkt.tag.sid);

		if (pkt.tag.type == VIO_TYPE_DATA) {
			vccdbgp(pkt);
			/* vcc_rx_check ensures memory availability */
			vcc_rx(tty, pkt.data, pkt.tag.stype);
		} else {
			pr_err("VCC: unknown msg [%02x:%02x:%04x:%08x]\n",
			       pkt.tag.type, pkt.tag.stype,
			       pkt.tag.stype_env, pkt.tag.sid);
			rv = -ECONNRESET;
			break;
		}

		WARN_ON(rv != LDC_PACKET_SIZE);
	}

done:
	return rv;
}

static void vcc_rx_timer(struct timer_list *t)
{
	struct vcc_port *port = from_timer(port, t, rx_timer);
	struct vio_driver_state *vio;
	unsigned long flags;
	int rv;

	spin_lock_irqsave(&port->lock, flags);
	port->rx_timer.expires = 0;

	vio = &port->vio;

	enable_irq(vio->vdev->rx_irq);

	if (!port->tty || port->removed)
		goto done;

	rv = vcc_ldc_read(port);
	if (rv == -ECONNRESET)
		vio_conn_reset(vio);

done:
	spin_unlock_irqrestore(&port->lock, flags);
	vcc_put(port, false);
}

static void vcc_tx_timer(struct timer_list *t)
{
	struct vcc_port *port = from_timer(port, t, tx_timer);
	struct vio_vcc *pkt;
	unsigned long flags;
	int tosend = 0;
	int rv;

	spin_lock_irqsave(&port->lock, flags);
	port->tx_timer.expires = 0;

	if (!port->tty || port->removed)
		goto done;

	tosend = min(VCC_BUFF_LEN, port->chars_in_buffer);
	if (!tosend)
		goto done;

	pkt = &port->buffer;
	pkt->tag.type = VIO_TYPE_DATA;
	pkt->tag.stype = tosend;
	vccdbgl(port->vio.lp);

	rv = ldc_write(port->vio.lp, pkt, (VIO_TAG_SIZE + tosend));
	WARN_ON(!rv);

	if (rv < 0) {
		vccdbg("VCC: ldc_write()=%d\n", rv);
		vcc_kick_tx(port);
	} else {
		struct tty_struct *tty = port->tty;

		port->chars_in_buffer = 0;
		if (tty)
			tty_wakeup(tty);
	}

done:
	spin_unlock_irqrestore(&port->lock, flags);
	vcc_put(port, false);
}

/**
 * vcc_event() - LDC event processing engine
 * @arg: VCC private data
 * @event: LDC event
 *
 * Handles LDC events for VCC
 */
static void vcc_event(void *arg, int event)
{
	struct vio_driver_state *vio;
	struct vcc_port *port;
	unsigned long flags;
	int rv;

	port = arg;
	vio = &port->vio;

	spin_lock_irqsave(&port->lock, flags);

	switch (event) {
	case LDC_EVENT_RESET:
	case LDC_EVENT_UP:
		vio_link_state_change(vio, event);
		break;

	case LDC_EVENT_DATA_READY:
		rv = vcc_ldc_read(port);
		if (rv == -ECONNRESET)
			vio_conn_reset(vio);
		break;

	default:
		pr_err("VCC: unexpected LDC event(%d)\n", event);
	}

	spin_unlock_irqrestore(&port->lock, flags);
}

static struct ldc_channel_config vcc_ldc_cfg = {
	.event		= vcc_event,
	.mtu		= VIO_VCC_MTU_SIZE,
	.mode		= LDC_MODE_RAW,
	.debug		= 0,
};

/* Ordered from largest major to lowest */
static struct vio_version vcc_versions[] = {
	{ .major = 1, .minor = 0 },
};

static struct tty_port_operations vcc_port_ops = { 0 };

static ssize_t vcc_sysfs_domain_show(struct device *dev,
				     struct device_attribute *attr,
				     char *buf)
{
	struct vcc_port *port;
	int rv;

	port = dev_get_drvdata(dev);
	if (!port)
		return -ENODEV;

	rv = scnprintf(buf, PAGE_SIZE, "%s\n", port->domain);

	return rv;
}

static int vcc_send_ctl(struct vcc_port *port, int ctl)
{
	struct vio_vcc pkt;
	int rv;

	pkt.tag.type = VIO_TYPE_CTRL;
	pkt.tag.sid = ctl;
	pkt.tag.stype = 0;

	rv = ldc_write(port->vio.lp, &pkt, sizeof(pkt.tag));
	WARN_ON(!rv);
	vccdbg("VCC: ldc_write(%ld)=%d\n", sizeof(pkt.tag), rv);

	return rv;
}

static ssize_t vcc_sysfs_break_store(struct device *dev,
				     struct device_attribute *attr,
				     const char *buf, size_t count)
{
	struct vcc_port *port;
	unsigned long flags;
	int rv = count;
	int brk;

	port = dev_get_drvdata(dev);
	if (!port)
		return -ENODEV;

	spin_lock_irqsave(&port->lock, flags);

	if (sscanf(buf, "%ud", &brk) != 1 || brk != 1)
		rv = -EINVAL;
	else if (vcc_send_ctl(port, VCC_CTL_BREAK) < 0)
		vcc_kick_tx(port);

	spin_unlock_irqrestore(&port->lock, flags);

	return rv;
}

static DEVICE_ATTR(domain, 0400, vcc_sysfs_domain_show, NULL);
static DEVICE_ATTR(break, 0200, NULL, vcc_sysfs_break_store);

static struct attribute *vcc_sysfs_entries[] = {
	&dev_attr_domain.attr,
	&dev_attr_break.attr,
	NULL
};

static struct attribute_group vcc_attribute_group = {
	.name = NULL,
	.attrs = vcc_sysfs_entries,
};

/**
 * vcc_probe() - Initialize VCC port
 * @vdev: Pointer to VIO device of the new VCC port
 * @id: VIO device ID
 *
 * Initializes a VCC port to receive serial console data from
 * the guest domain. Sets up a TTY end point on the control
 * domain. Sets up VIO/LDC link between the guest & control
 * domain endpoints.
 *
 * Return: status of the probe
 */
static int vcc_probe(struct vio_dev *vdev, const struct vio_device_id *id)
{
	struct mdesc_handle *hp;
	struct vcc_port *port;
	struct device *dev;
	const char *domain;
	char *name;
	u64 node;
	int rv;

	vccdbg("VCC: name=%s\n", dev_name(&vdev->dev));

	if (!vcc_tty_driver) {
		pr_err("VCC: TTY driver not registered\n");
		return -ENODEV;
	}

	port = kzalloc(sizeof(struct vcc_port), GFP_KERNEL);
	if (!port)
		return -ENOMEM;

	name = kstrdup(dev_name(&vdev->dev), GFP_KERNEL);

	rv = vio_driver_init(&port->vio, vdev, VDEV_CONSOLE_CON, vcc_versions,
			     ARRAY_SIZE(vcc_versions), NULL, name);
	if (rv)
		goto free_port;

	port->vio.debug = vcc_dbg_vio;
	vcc_ldc_cfg.debug = vcc_dbg_ldc;

	rv = vio_ldc_alloc(&port->vio, &vcc_ldc_cfg, port);
	if (rv)
		goto free_port;

	spin_lock_init(&port->lock);

	port->index = vcc_table_add(port);
	if (port->index == -1) {
		pr_err("VCC: no more TTY indices left for allocation\n");
		rv = -ENOMEM;
		goto free_ldc;
	}

	/* Register the device using VCC table index as TTY index */
	dev = tty_register_device(vcc_tty_driver, port->index, &vdev->dev);
	if (IS_ERR(dev)) {
		rv = PTR_ERR(dev);
		goto free_table;
	}

	hp = mdesc_grab();

	node = vio_vdev_node(hp, vdev);
	if (node == MDESC_NODE_NULL) {
		rv = -ENXIO;
		mdesc_release(hp);
		goto unreg_tty;
	}

	domain = mdesc_get_property(hp, node, "vcc-domain-name", NULL);
	if (!domain) {
		rv = -ENXIO;
		mdesc_release(hp);
		goto unreg_tty;
	}
	port->domain = kstrdup(domain, GFP_KERNEL);

	mdesc_release(hp);

	rv = sysfs_create_group(&vdev->dev.kobj, &vcc_attribute_group);
	if (rv)
		goto free_domain;

	timer_setup(&port->rx_timer, vcc_rx_timer, 0);
	timer_setup(&port->tx_timer, vcc_tx_timer, 0);

	dev_set_drvdata(&vdev->dev, port);

	/* It's possible to receive IRQs in the middle of vio_port_up. Disable
	 * IRQs until the port is up.
	 */
	disable_irq_nosync(vdev->rx_irq);
	vio_port_up(&port->vio);
	enable_irq(vdev->rx_irq);

	return 0;

free_domain:
	kfree(port->domain);
unreg_tty:
	tty_unregister_device(vcc_tty_driver, port->index);
free_table:
	vcc_table_remove(port->index);
free_ldc:
	vio_ldc_free(&port->vio);
free_port:
	kfree(name);
	kfree(port);

	return rv;
}

/**
 * vcc_remove() - Terminate a VCC port
 * @vdev: Pointer to VIO device of the VCC port
 *
 * Terminates a VCC port. Sets up the teardown of TTY and
 * VIO/LDC link between guest and primary domains.
 *
 * Return: status of removal
 */
static int vcc_remove(struct vio_dev *vdev)
{
	struct vcc_port *port = dev_get_drvdata(&vdev->dev);

	if (!port)
		return -ENODEV;

	del_timer_sync(&port->rx_timer);
	del_timer_sync(&port->tx_timer);

	/* If there's a process with the device open, do a synchronous
	 * hangup of the TTY. This *may* cause the process to call close
	 * asynchronously, but it's not guaranteed.
	 */
	if (port->tty)
		tty_vhangup(port->tty);

	/* Get exclusive reference to VCC, ensures that there are no other
	 * clients to this port
	 */
	port = vcc_get(port->index, true);

	if (WARN_ON(!port))
		return -ENODEV;

	tty_unregister_device(vcc_tty_driver, port->index);

	del_timer_sync(&port->vio.timer);
	vio_ldc_free(&port->vio);
	sysfs_remove_group(&vdev->dev.kobj, &vcc_attribute_group);
	dev_set_drvdata(&vdev->dev, NULL);
	if (port->tty) {
		port->removed = true;
		vcc_put(port, true);
	} else {
		vcc_table_remove(port->index);

		kfree(port->vio.name);
		kfree(port->domain);
		kfree(port);
	}

	return 0;
}

static const struct vio_device_id vcc_match[] = {
	{
		.type = "vcc-port",
	},
	{},
};
MODULE_DEVICE_TABLE(vio, vcc_match);

static struct vio_driver vcc_driver = {
	.id_table	= vcc_match,
	.probe		= vcc_probe,
	.remove		= vcc_remove,
	.name		= "vcc",
};

static int vcc_open(struct tty_struct *tty, struct file *vcc_file)
{
	struct vcc_port *port;

	if (unlikely(!tty)) {
		pr_err("VCC: open: Invalid TTY handle\n");
		return -ENXIO;
	}

	if (tty->count > 1)
		return -EBUSY;

	port = vcc_get_ne(tty->index);
	if (unlikely(!port)) {
		pr_err("VCC: open: Failed to find VCC port\n");
		return -ENODEV;
	}

	if (unlikely(!port->vio.lp)) {
		pr_err("VCC: open: LDC channel not configured\n");
		vcc_put(port, false);
		return -EPIPE;
	}
	vccdbgl(port->vio.lp);

	vcc_put(port, false);

	if (unlikely(!tty->port)) {
		pr_err("VCC: open: TTY port not found\n");
		return -ENXIO;
	}

	if (unlikely(!tty->port->ops)) {
		pr_err("VCC: open: TTY ops not defined\n");
		return -ENXIO;
	}

	return tty_port_open(tty->port, tty, vcc_file);
}

static void vcc_close(struct tty_struct *tty, struct file *vcc_file)
{
	if (unlikely(!tty)) {
		pr_err("VCC: close: Invalid TTY handle\n");
		return;
	}

	if (unlikely(tty->count > 1))
		return;

	if (unlikely(!tty->port)) {
		pr_err("VCC: close: TTY port not found\n");
		return;
	}

	tty_port_close(tty->port, tty, vcc_file);
}

static void vcc_ldc_hup(struct vcc_port *port)
{
	unsigned long flags;

	spin_lock_irqsave(&port->lock, flags);

	if (vcc_send_ctl(port, VCC_CTL_HUP) < 0)
		vcc_kick_tx(port);

	spin_unlock_irqrestore(&port->lock, flags);
}

static void vcc_hangup(struct tty_struct *tty)
{
	struct vcc_port *port;

	if (unlikely(!tty)) {
		pr_err("VCC: hangup: Invalid TTY handle\n");
		return;
	}

	port = vcc_get_ne(tty->index);
	if (unlikely(!port)) {
		pr_err("VCC: hangup: Failed to find VCC port\n");
		return;
	}

	if (unlikely(!tty->port)) {
		pr_err("VCC: hangup: TTY port not found\n");
		vcc_put(port, false);
		return;
	}

	vcc_ldc_hup(port);

	vcc_put(port, false);

	tty_port_hangup(tty->port);
}

static int vcc_write(struct tty_struct *tty, const unsigned char *buf,
		     int count)
{
	struct vcc_port *port;
	struct vio_vcc *pkt;
	unsigned long flags;
	int total_sent = 0;
	int tosend = 0;
	int rv = -EINVAL;

	if (unlikely(!tty)) {
		pr_err("VCC: write: Invalid TTY handle\n");
		return -ENXIO;
	}

	port = vcc_get_ne(tty->index);
	if (unlikely(!port)) {
		pr_err("VCC: write: Failed to find VCC port");
		return -ENODEV;
	}

	spin_lock_irqsave(&port->lock, flags);

	pkt = &port->buffer;
	pkt->tag.type = VIO_TYPE_DATA;

	while (count > 0) {
		/* Minimum of data to write and space available */
		tosend = min(count, (VCC_BUFF_LEN - port->chars_in_buffer));

		if (!tosend)
			break;

		memcpy(&pkt->data[port->chars_in_buffer], &buf[total_sent],
		       tosend);
		port->chars_in_buffer += tosend;
		pkt->tag.stype = tosend;

		vccdbg("TAG [%02x:%02x:%04x:%08x]\n", pkt->tag.type,
		       pkt->tag.stype, pkt->tag.stype_env, pkt->tag.sid);
		vccdbg("DATA [%s]\n", pkt->data);
		vccdbgl(port->vio.lp);

		/* Since we know we have enough room in VCC buffer for tosend
		 * we record that it was sent regardless of whether the
		 * hypervisor actually took it because we have it buffered.
		 */
		rv = ldc_write(port->vio.lp, pkt, (VIO_TAG_SIZE + tosend));
		vccdbg("VCC: write: ldc_write(%d)=%d\n",
		       (VIO_TAG_SIZE + tosend), rv);

		total_sent += tosend;
		count -= tosend;
		if (rv < 0) {
			vcc_kick_tx(port);
			break;
		}

		port->chars_in_buffer = 0;
	}

	spin_unlock_irqrestore(&port->lock, flags);

	vcc_put(port, false);

	vccdbg("VCC: write: total=%d rv=%d", total_sent, rv);

	return total_sent ? total_sent : rv;
}

static int vcc_write_room(struct tty_struct *tty)
{
	struct vcc_port *port;
	u64 num;

	if (unlikely(!tty)) {
		pr_err("VCC: write_room: Invalid TTY handle\n");
		return -ENXIO;
	}

	port = vcc_get_ne(tty->index);
	if (unlikely(!port)) {
		pr_err("VCC: write_room: Failed to find VCC port\n");
		return -ENODEV;
	}

	num = VCC_BUFF_LEN - port->chars_in_buffer;

	vcc_put(port, false);

	return num;
}

static int vcc_chars_in_buffer(struct tty_struct *tty)
{
	struct vcc_port *port;
	u64 num;

	if (unlikely(!tty)) {
		pr_err("VCC: chars_in_buffer: Invalid TTY handle\n");
		return -ENXIO;
	}

	port = vcc_get_ne(tty->index);
	if (unlikely(!port)) {
		pr_err("VCC: chars_in_buffer: Failed to find VCC port\n");
		return -ENODEV;
	}

	num = port->chars_in_buffer;

	vcc_put(port, false);

	return num;
}

static int vcc_break_ctl(struct tty_struct *tty, int state)
{
	struct vcc_port *port;
	unsigned long flags;

	if (unlikely(!tty)) {
		pr_err("VCC: break_ctl: Invalid TTY handle\n");
		return -ENXIO;
	}

	port = vcc_get_ne(tty->index);
	if (unlikely(!port)) {
		pr_err("VCC: break_ctl: Failed to find VCC port\n");
		return -ENODEV;
	}

	/* Turn off break */
	if (state == 0) {
		vcc_put(port, false);
		return 0;
	}

	spin_lock_irqsave(&port->lock, flags);

	if (vcc_send_ctl(port, VCC_CTL_BREAK) < 0)
		vcc_kick_tx(port);

	spin_unlock_irqrestore(&port->lock, flags);

	vcc_put(port, false);

	return 0;
}

static int vcc_install(struct tty_driver *driver, struct tty_struct *tty)
{
	struct vcc_port *port_vcc;
	struct tty_port *port_tty;
	int ret;

	if (unlikely(!tty)) {
		pr_err("VCC: install: Invalid TTY handle\n");
		return -ENXIO;
	}

	if (tty->index >= VCC_MAX_PORTS)
		return -EINVAL;

	ret = tty_standard_install(driver, tty);
	if (ret)
		return ret;

	port_tty = kzalloc(sizeof(struct tty_port), GFP_KERNEL);
	if (!port_tty)
		return -ENOMEM;

	port_vcc = vcc_get(tty->index, true);
	if (!port_vcc) {
		pr_err("VCC: install: Failed to find VCC port\n");
		tty->port = NULL;
		kfree(port_tty);
		return -ENODEV;
	}

	tty_port_init(port_tty);
	port_tty->ops = &vcc_port_ops;
	tty->port = port_tty;

	port_vcc->tty = tty;

	vcc_put(port_vcc, true);

	return 0;
}

static void vcc_cleanup(struct tty_struct *tty)
{
	struct vcc_port *port;

	if (unlikely(!tty)) {
		pr_err("VCC: cleanup: Invalid TTY handle\n");
		return;
	}

	port = vcc_get(tty->index, true);
	if (port) {
		port->tty = NULL;

		if (port->removed) {
			vcc_table_remove(tty->index);
			kfree(port->vio.name);
			kfree(port->domain);
			kfree(port);
		} else {
			vcc_put(port, true);
		}
	}

	tty_port_destroy(tty->port);
	kfree(tty->port);
	tty->port = NULL;
}

static const struct tty_operations vcc_ops = {
	.open			= vcc_open,
	.close			= vcc_close,
	.hangup			= vcc_hangup,
	.write			= vcc_write,
	.write_room		= vcc_write_room,
	.chars_in_buffer	= vcc_chars_in_buffer,
	.break_ctl		= vcc_break_ctl,
	.install		= vcc_install,
	.cleanup		= vcc_cleanup,
};

#define VCC_TTY_FLAGS   (TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_REAL_RAW)

static int vcc_tty_init(void)
{
	int rv;

	pr_info("VCC: %s\n", version);

	vcc_tty_driver = tty_alloc_driver(VCC_MAX_PORTS, VCC_TTY_FLAGS);
	if (IS_ERR(vcc_tty_driver)) {
		pr_err("VCC: TTY driver alloc failed\n");
		return PTR_ERR(vcc_tty_driver);
	}

	vcc_tty_driver->driver_name = vcc_driver_name;
	vcc_tty_driver->name = vcc_device_node;

	vcc_tty_driver->minor_start = VCC_MINOR_START;
	vcc_tty_driver->type = TTY_DRIVER_TYPE_SYSTEM;
	vcc_tty_driver->init_termios = vcc_tty_termios;

	tty_set_operations(vcc_tty_driver, &vcc_ops);

	rv = tty_register_driver(vcc_tty_driver);
	if (rv) {
		pr_err("VCC: TTY driver registration failed\n");
		put_tty_driver(vcc_tty_driver);
		vcc_tty_driver = NULL;
		return rv;
	}

	vccdbg("VCC: TTY driver registered\n");

	return 0;
}

static void vcc_tty_exit(void)
{
	tty_unregister_driver(vcc_tty_driver);
	put_tty_driver(vcc_tty_driver);
	vccdbg("VCC: TTY driver unregistered\n");

	vcc_tty_driver = NULL;
}

static int __init vcc_init(void)
{
	int rv;

	rv = vcc_tty_init();
	if (rv) {
		pr_err("VCC: TTY init failed\n");
		return rv;
	}

	rv = vio_register_driver(&vcc_driver);
	if (rv) {
		pr_err("VCC: VIO driver registration failed\n");
		vcc_tty_exit();
	} else {
		vccdbg("VCC: VIO driver registered successfully\n");
	}

	return rv;
}

static void __exit vcc_exit(void)
{
	vio_unregister_driver(&vcc_driver);
	vccdbg("VCC: VIO driver unregistered\n");
	vcc_tty_exit();
	vccdbg("VCC: TTY driver unregistered\n");
}

module_init(vcc_init);
module_exit(vcc_exit);