summaryrefslogtreecommitdiff
path: root/drivers/s390/char/sclp.c
blob: 4138564402b8c2ee27b3bf04731bebe1c3caf35e (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
/*
 *  drivers/s390/char/sclp.c
 *     core function to access sclp interface
 *
 *  S390 version
 *    Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
 *    Author(s): Martin Peschke <mpeschke@de.ibm.com>
 *		 Martin Schwidefsky <schwidefsky@de.ibm.com>
 */

#include <linux/module.h>
#include <linux/err.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/timer.h>
#include <linux/reboot.h>
#include <linux/jiffies.h>
#include <asm/types.h>
#include <asm/s390_ext.h>

#include "sclp.h"

#define SCLP_HEADER		"sclp: "

/* Structure for register_early_external_interrupt. */
static ext_int_info_t ext_int_info_hwc;

/* Lock to protect internal data consistency. */
static DEFINE_SPINLOCK(sclp_lock);

/* Mask of events that we can receive from the sclp interface. */
static sccb_mask_t sclp_receive_mask;

/* Mask of events that we can send to the sclp interface. */
static sccb_mask_t sclp_send_mask;

/* List of registered event listeners and senders. */
static struct list_head sclp_reg_list;

/* List of queued requests. */
static struct list_head sclp_req_queue;

/* Data for read and and init requests. */
static struct sclp_req sclp_read_req;
static struct sclp_req sclp_init_req;
static char sclp_read_sccb[PAGE_SIZE] __attribute__((__aligned__(PAGE_SIZE)));
static char sclp_init_sccb[PAGE_SIZE] __attribute__((__aligned__(PAGE_SIZE)));

/* Timer for request retries. */
static struct timer_list sclp_request_timer;

/* Internal state: is the driver initialized? */
static volatile enum sclp_init_state_t {
	sclp_init_state_uninitialized,
	sclp_init_state_initializing,
	sclp_init_state_initialized
} sclp_init_state = sclp_init_state_uninitialized;

/* Internal state: is a request active at the sclp? */
static volatile enum sclp_running_state_t {
	sclp_running_state_idle,
	sclp_running_state_running
} sclp_running_state = sclp_running_state_idle;

/* Internal state: is a read request pending? */
static volatile enum sclp_reading_state_t {
	sclp_reading_state_idle,
	sclp_reading_state_reading
} sclp_reading_state = sclp_reading_state_idle;

/* Internal state: is the driver currently serving requests? */
static volatile enum sclp_activation_state_t {
	sclp_activation_state_active,
	sclp_activation_state_deactivating,
	sclp_activation_state_inactive,
	sclp_activation_state_activating
} sclp_activation_state = sclp_activation_state_active;

/* Internal state: is an init mask request pending? */
static volatile enum sclp_mask_state_t {
	sclp_mask_state_idle,
	sclp_mask_state_initializing
} sclp_mask_state = sclp_mask_state_idle;

/* Maximum retry counts */
#define SCLP_INIT_RETRY		3
#define SCLP_MASK_RETRY		3

/* Timeout intervals in seconds.*/
#define SCLP_BUSY_INTERVAL	10
#define SCLP_RETRY_INTERVAL	15

static void sclp_process_queue(void);
static int sclp_init_mask(int calculate);
static int sclp_init(void);

/* Perform service call. Return 0 on success, non-zero otherwise. */
static int
service_call(sclp_cmdw_t command, void *sccb)
{
	int cc;

	__asm__ __volatile__(
		"   .insn rre,0xb2200000,%1,%2\n"  /* servc %1,%2 */
		"   ipm	  %0\n"
		"   srl	  %0,28"
		: "=&d" (cc)
		: "d" (command), "a" (__pa(sccb))
		: "cc", "memory" );
	if (cc == 3)
		return -EIO;
	if (cc == 2)
		return -EBUSY;
	return 0;
}

/* Request timeout handler. Restart the request queue. If DATA is non-zero,
 * force restart of running request. */
static void
sclp_request_timeout(unsigned long data)
{
	unsigned long flags;

	if (data) {
		spin_lock_irqsave(&sclp_lock, flags);
		sclp_running_state = sclp_running_state_idle;
		spin_unlock_irqrestore(&sclp_lock, flags);
	}
	sclp_process_queue();
}

/* Set up request retry timer. Called while sclp_lock is locked. */
static inline void
__sclp_set_request_timer(unsigned long time, void (*function)(unsigned long),
			 unsigned long data)
{
	del_timer(&sclp_request_timer);
	sclp_request_timer.function = function;
	sclp_request_timer.data = data;
	sclp_request_timer.expires = jiffies + time;
	add_timer(&sclp_request_timer);
}

/* Try to start a request. Return zero if the request was successfully
 * started or if it will be started at a later time. Return non-zero otherwise.
 * Called while sclp_lock is locked. */
static int
__sclp_start_request(struct sclp_req *req)
{
	int rc;

	if (sclp_running_state != sclp_running_state_idle)
		return 0;
	del_timer(&sclp_request_timer);
	rc = service_call(req->command, req->sccb);
	req->start_count++;

	if (rc == 0) {
		/* Sucessfully started request */
		req->status = SCLP_REQ_RUNNING;
		sclp_running_state = sclp_running_state_running;
		__sclp_set_request_timer(SCLP_RETRY_INTERVAL * HZ,
					 sclp_request_timeout, 1);
		return 0;
	} else if (rc == -EBUSY) {
		/* Try again later */
		__sclp_set_request_timer(SCLP_BUSY_INTERVAL * HZ,
					 sclp_request_timeout, 0);
		return 0;
	}
	/* Request failed */
	req->status = SCLP_REQ_FAILED;
	return rc;
}

/* Try to start queued requests. */
static void
sclp_process_queue(void)
{
	struct sclp_req *req;
	int rc;
	unsigned long flags;

	spin_lock_irqsave(&sclp_lock, flags);
	if (sclp_running_state != sclp_running_state_idle) {
		spin_unlock_irqrestore(&sclp_lock, flags);
		return;
	}
	del_timer(&sclp_request_timer);
	while (!list_empty(&sclp_req_queue)) {
		req = list_entry(sclp_req_queue.next, struct sclp_req, list);
		rc = __sclp_start_request(req);
		if (rc == 0)
			break;
		/* Request failed. */
		list_del(&req->list);
		if (req->callback) {
			spin_unlock_irqrestore(&sclp_lock, flags);
			req->callback(req, req->callback_data);
			spin_lock_irqsave(&sclp_lock, flags);
		}
	}
	spin_unlock_irqrestore(&sclp_lock, flags);
}

/* Queue a new request. Return zero on success, non-zero otherwise. */
int
sclp_add_request(struct sclp_req *req)
{
	unsigned long flags;
	int rc;

	spin_lock_irqsave(&sclp_lock, flags);
	if ((sclp_init_state != sclp_init_state_initialized ||
	     sclp_activation_state != sclp_activation_state_active) &&
	    req != &sclp_init_req) {
		spin_unlock_irqrestore(&sclp_lock, flags);
		return -EIO;
	}
	req->status = SCLP_REQ_QUEUED;
	req->start_count = 0;
	list_add_tail(&req->list, &sclp_req_queue);
	rc = 0;
	/* Start if request is first in list */
	if (req->list.prev == &sclp_req_queue) {
		rc = __sclp_start_request(req);
		if (rc)
			list_del(&req->list);
	}
	spin_unlock_irqrestore(&sclp_lock, flags);
	return rc;
}

EXPORT_SYMBOL(sclp_add_request);

/* Dispatch events found in request buffer to registered listeners. Return 0
 * if all events were dispatched, non-zero otherwise. */
static int
sclp_dispatch_evbufs(struct sccb_header *sccb)
{
	unsigned long flags;
	struct evbuf_header *evbuf;
	struct list_head *l;
	struct sclp_register *reg;
	int offset;
	int rc;

	spin_lock_irqsave(&sclp_lock, flags);
	rc = 0;
	for (offset = sizeof(struct sccb_header); offset < sccb->length;
	     offset += evbuf->length) {
		/* Search for event handler */
		evbuf = (struct evbuf_header *) ((addr_t) sccb + offset);
		reg = NULL;
		list_for_each(l, &sclp_reg_list) {
			reg = list_entry(l, struct sclp_register, list);
			if (reg->receive_mask & (1 << (32 - evbuf->type)))
				break;
			else
				reg = NULL;
		}
		if (reg && reg->receiver_fn) {
			spin_unlock_irqrestore(&sclp_lock, flags);
			reg->receiver_fn(evbuf);
			spin_lock_irqsave(&sclp_lock, flags);
		} else if (reg == NULL)
			rc = -ENOSYS;
	}
	spin_unlock_irqrestore(&sclp_lock, flags);
	return rc;
}

/* Read event data request callback. */
static void
sclp_read_cb(struct sclp_req *req, void *data)
{
	unsigned long flags;
	struct sccb_header *sccb;

	sccb = (struct sccb_header *) req->sccb;
	if (req->status == SCLP_REQ_DONE && (sccb->response_code == 0x20 ||
	    sccb->response_code == 0x220))
		sclp_dispatch_evbufs(sccb);
	spin_lock_irqsave(&sclp_lock, flags);
	sclp_reading_state = sclp_reading_state_idle;
	spin_unlock_irqrestore(&sclp_lock, flags);
}

/* Prepare read event data request. Called while sclp_lock is locked. */
static inline void
__sclp_make_read_req(void)
{
	struct sccb_header *sccb;

	sccb = (struct sccb_header *) sclp_read_sccb;
	clear_page(sccb);
	memset(&sclp_read_req, 0, sizeof(struct sclp_req));
	sclp_read_req.command = SCLP_CMDW_READDATA;
	sclp_read_req.status = SCLP_REQ_QUEUED;
	sclp_read_req.start_count = 0;
	sclp_read_req.callback = sclp_read_cb;
	sclp_read_req.sccb = sccb;
	sccb->length = PAGE_SIZE;
	sccb->function_code = 0;
	sccb->control_mask[2] = 0x80;
}

/* Search request list for request with matching sccb. Return request if found,
 * NULL otherwise. Called while sclp_lock is locked. */
static inline struct sclp_req *
__sclp_find_req(u32 sccb)
{
	struct list_head *l;
	struct sclp_req *req;

	list_for_each(l, &sclp_req_queue) {
		req = list_entry(l, struct sclp_req, list);
		if (sccb == (u32) (addr_t) req->sccb)
				return req;
	}
	return NULL;
}

/* Handler for external interruption. Perform request post-processing.
 * Prepare read event data request if necessary. Start processing of next
 * request on queue. */
static void
sclp_interrupt_handler(struct pt_regs *regs, __u16 code)
{
	struct sclp_req *req;
	u32 finished_sccb;
	u32 evbuf_pending;

	spin_lock(&sclp_lock);
	finished_sccb = S390_lowcore.ext_params & 0xfffffff8;
	evbuf_pending = S390_lowcore.ext_params & 0x3;
	if (finished_sccb) {
		req = __sclp_find_req(finished_sccb);
		if (req) {
			/* Request post-processing */
			list_del(&req->list);
			req->status = SCLP_REQ_DONE;
			if (req->callback) {
				spin_unlock(&sclp_lock);
				req->callback(req, req->callback_data);
				spin_lock(&sclp_lock);
			}
		}
		sclp_running_state = sclp_running_state_idle;
	}
	if (evbuf_pending && sclp_receive_mask != 0 &&
	    sclp_reading_state == sclp_reading_state_idle &&
	    sclp_activation_state == sclp_activation_state_active ) {
		sclp_reading_state = sclp_reading_state_reading;
		__sclp_make_read_req();
		/* Add request to head of queue */
		list_add(&sclp_read_req.list, &sclp_req_queue);
	}
	spin_unlock(&sclp_lock);
	sclp_process_queue();
}

/* Return current Time-Of-Day clock. */
static inline u64
sclp_get_clock(void)
{
	u64 result;

	asm volatile ("STCK 0(%1)" : "=m" (result) : "a" (&(result)) : "cc");
	return result;
}

/* Convert interval in jiffies to TOD ticks. */
static inline u64
sclp_tod_from_jiffies(unsigned long jiffies)
{
	return (u64) (jiffies / HZ) << 32;
}

/* Wait until a currently running request finished. Note: while this function
 * is running, no timers are served on the calling CPU. */
void
sclp_sync_wait(void)
{
	unsigned long psw_mask;
	unsigned long cr0, cr0_sync;
	u64 timeout;

	/* We'll be disabling timer interrupts, so we need a custom timeout
	 * mechanism */
	timeout = 0;
	if (timer_pending(&sclp_request_timer)) {
		/* Get timeout TOD value */
		timeout = sclp_get_clock() +
			  sclp_tod_from_jiffies(sclp_request_timer.expires -
						jiffies);
	}
	/* Prevent bottom half from executing once we force interrupts open */
	local_bh_disable();
	/* Enable service-signal interruption, disable timer interrupts */
	__ctl_store(cr0, 0, 0);
	cr0_sync = cr0;
	cr0_sync |= 0x00000200;
	cr0_sync &= 0xFFFFF3AC;
	__ctl_load(cr0_sync, 0, 0);
	asm volatile ("STOSM 0(%1),0x01"
		      : "=m" (psw_mask) : "a" (&psw_mask) : "memory");
	/* Loop until driver state indicates finished request */
	while (sclp_running_state != sclp_running_state_idle) {
		/* Check for expired request timer */
		if (timer_pending(&sclp_request_timer) &&
		    sclp_get_clock() > timeout &&
		    del_timer(&sclp_request_timer))
			sclp_request_timer.function(sclp_request_timer.data);
		barrier();
		cpu_relax();
	}
	/* Restore interrupt settings */
	asm volatile ("SSM 0(%0)"
		      : : "a" (&psw_mask) : "memory");
	__ctl_load(cr0, 0, 0);
	__local_bh_enable();
}

EXPORT_SYMBOL(sclp_sync_wait);

/* Dispatch changes in send and receive mask to registered listeners. */
static inline void
sclp_dispatch_state_change(void)
{
	struct list_head *l;
	struct sclp_register *reg;
	unsigned long flags;
	sccb_mask_t receive_mask;
	sccb_mask_t send_mask;

	do {
		spin_lock_irqsave(&sclp_lock, flags);
		reg = NULL;
		list_for_each(l, &sclp_reg_list) {
			reg = list_entry(l, struct sclp_register, list);
			receive_mask = reg->receive_mask & sclp_receive_mask;
			send_mask = reg->send_mask & sclp_send_mask;
			if (reg->sclp_receive_mask != receive_mask ||
			    reg->sclp_send_mask != send_mask) {
				reg->sclp_receive_mask = receive_mask;
				reg->sclp_send_mask = send_mask;
				break;
			} else
				reg = NULL;
		}
		spin_unlock_irqrestore(&sclp_lock, flags);
		if (reg && reg->state_change_fn)
			reg->state_change_fn(reg);
	} while (reg);
}

struct sclp_statechangebuf {
	struct evbuf_header	header;
	u8		validity_sclp_active_facility_mask : 1;
	u8		validity_sclp_receive_mask : 1;
	u8		validity_sclp_send_mask : 1;
	u8		validity_read_data_function_mask : 1;
	u16		_zeros : 12;
	u16		mask_length;
	u64		sclp_active_facility_mask;
	sccb_mask_t	sclp_receive_mask;
	sccb_mask_t	sclp_send_mask;
	u32		read_data_function_mask;
} __attribute__((packed));


/* State change event callback. Inform listeners of changes. */
static void
sclp_state_change_cb(struct evbuf_header *evbuf)
{
	unsigned long flags;
	struct sclp_statechangebuf *scbuf;

	scbuf = (struct sclp_statechangebuf *) evbuf;
	if (scbuf->mask_length != sizeof(sccb_mask_t))
		return;
	spin_lock_irqsave(&sclp_lock, flags);
	if (scbuf->validity_sclp_receive_mask)
		sclp_receive_mask = scbuf->sclp_receive_mask;
	if (scbuf->validity_sclp_send_mask)
		sclp_send_mask = scbuf->sclp_send_mask;
	spin_unlock_irqrestore(&sclp_lock, flags);
	sclp_dispatch_state_change();
}

static struct sclp_register sclp_state_change_event = {
	.receive_mask = EvTyp_StateChange_Mask,
	.receiver_fn = sclp_state_change_cb
};

/* Calculate receive and send mask of currently registered listeners.
 * Called while sclp_lock is locked. */
static inline void
__sclp_get_mask(sccb_mask_t *receive_mask, sccb_mask_t *send_mask)
{
	struct list_head *l;
	struct sclp_register *t;

	*receive_mask = 0;
	*send_mask = 0;
	list_for_each(l, &sclp_reg_list) {
		t = list_entry(l, struct sclp_register, list);
		*receive_mask |= t->receive_mask;
		*send_mask |= t->send_mask;
	}
}

/* Register event listener. Return 0 on success, non-zero otherwise. */
int
sclp_register(struct sclp_register *reg)
{
	unsigned long flags;
	sccb_mask_t receive_mask;
	sccb_mask_t send_mask;
	int rc;

	rc = sclp_init();
	if (rc)
		return rc;
	spin_lock_irqsave(&sclp_lock, flags);
	/* Check event mask for collisions */
	__sclp_get_mask(&receive_mask, &send_mask);
	if (reg->receive_mask & receive_mask || reg->send_mask & send_mask) {
		spin_unlock_irqrestore(&sclp_lock, flags);
		return -EBUSY;
	}
	/* Trigger initial state change callback */
	reg->sclp_receive_mask = 0;
	reg->sclp_send_mask = 0;
	list_add(&reg->list, &sclp_reg_list);
	spin_unlock_irqrestore(&sclp_lock, flags);
	rc = sclp_init_mask(1);
	if (rc) {
		spin_lock_irqsave(&sclp_lock, flags);
		list_del(&reg->list);
		spin_unlock_irqrestore(&sclp_lock, flags);
	}
	return rc;
}

EXPORT_SYMBOL(sclp_register);

/* Unregister event listener. */
void
sclp_unregister(struct sclp_register *reg)
{
	unsigned long flags;

	spin_lock_irqsave(&sclp_lock, flags);
	list_del(&reg->list);
	spin_unlock_irqrestore(&sclp_lock, flags);
	sclp_init_mask(1);
}

EXPORT_SYMBOL(sclp_unregister);

/* Remove event buffers which are marked processed. Return the number of
 * remaining event buffers. */
int
sclp_remove_processed(struct sccb_header *sccb)
{
	struct evbuf_header *evbuf;
	int unprocessed;
	u16 remaining;

	evbuf = (struct evbuf_header *) (sccb + 1);
	unprocessed = 0;
	remaining = sccb->length - sizeof(struct sccb_header);
	while (remaining > 0) {
		remaining -= evbuf->length;
		if (evbuf->flags & 0x80) {
			sccb->length -= evbuf->length;
			memcpy(evbuf, (void *) ((addr_t) evbuf + evbuf->length),
			       remaining);
		} else {
			unprocessed++;
			evbuf = (struct evbuf_header *)
					((addr_t) evbuf + evbuf->length);
		}
	}
	return unprocessed;
}

EXPORT_SYMBOL(sclp_remove_processed);

struct init_sccb {
	struct sccb_header header;
	u16 _reserved;
	u16 mask_length;
	sccb_mask_t receive_mask;
	sccb_mask_t send_mask;
	sccb_mask_t sclp_send_mask;
	sccb_mask_t sclp_receive_mask;
} __attribute__((packed));

/* Prepare init mask request. Called while sclp_lock is locked. */
static inline void
__sclp_make_init_req(u32 receive_mask, u32 send_mask)
{
	struct init_sccb *sccb;

	sccb = (struct init_sccb *) sclp_init_sccb;
	clear_page(sccb);
	memset(&sclp_init_req, 0, sizeof(struct sclp_req));
	sclp_init_req.command = SCLP_CMDW_WRITEMASK;
	sclp_init_req.status = SCLP_REQ_FILLED;
	sclp_init_req.start_count = 0;
	sclp_init_req.callback = NULL;
	sclp_init_req.callback_data = NULL;
	sclp_init_req.sccb = sccb;
	sccb->header.length = sizeof(struct init_sccb);
	sccb->mask_length = sizeof(sccb_mask_t);
	sccb->receive_mask = receive_mask;
	sccb->send_mask = send_mask;
	sccb->sclp_receive_mask = 0;
	sccb->sclp_send_mask = 0;
}

/* Start init mask request. If calculate is non-zero, calculate the mask as
 * requested by registered listeners. Use zero mask otherwise. Return 0 on
 * success, non-zero otherwise. */
static int
sclp_init_mask(int calculate)
{
	unsigned long flags;
	struct init_sccb *sccb = (struct init_sccb *) sclp_init_sccb;
	sccb_mask_t receive_mask;
	sccb_mask_t send_mask;
	int retry;
	int rc;
	unsigned long wait;

	spin_lock_irqsave(&sclp_lock, flags);
	/* Check if interface is in appropriate state */
	if (sclp_mask_state != sclp_mask_state_idle) {
		spin_unlock_irqrestore(&sclp_lock, flags);
		return -EBUSY;
	}
	if (sclp_activation_state == sclp_activation_state_inactive) {
		spin_unlock_irqrestore(&sclp_lock, flags);
		return -EINVAL;
	}
	sclp_mask_state = sclp_mask_state_initializing;
	/* Determine mask */
	if (calculate)
		__sclp_get_mask(&receive_mask, &send_mask);
	else {
		receive_mask = 0;
		send_mask = 0;
	}
	rc = -EIO;
	for (retry = 0; retry <= SCLP_MASK_RETRY; retry++) {
		/* Prepare request */
		__sclp_make_init_req(receive_mask, send_mask);
		spin_unlock_irqrestore(&sclp_lock, flags);
		if (sclp_add_request(&sclp_init_req)) {
			/* Try again later */
			wait = jiffies + SCLP_BUSY_INTERVAL * HZ;
			while (time_before(jiffies, wait))
				sclp_sync_wait();
			spin_lock_irqsave(&sclp_lock, flags);
			continue;
		}
		while (sclp_init_req.status != SCLP_REQ_DONE &&
		       sclp_init_req.status != SCLP_REQ_FAILED)
			sclp_sync_wait();
		spin_lock_irqsave(&sclp_lock, flags);
		if (sclp_init_req.status == SCLP_REQ_DONE &&
		    sccb->header.response_code == 0x20) {
			/* Successful request */
			if (calculate) {
				sclp_receive_mask = sccb->sclp_receive_mask;
				sclp_send_mask = sccb->sclp_send_mask;
			} else {
				sclp_receive_mask = 0;
				sclp_send_mask = 0;
			}
			spin_unlock_irqrestore(&sclp_lock, flags);
			sclp_dispatch_state_change();
			spin_lock_irqsave(&sclp_lock, flags);
			rc = 0;
			break;
		}
	}
	sclp_mask_state = sclp_mask_state_idle;
	spin_unlock_irqrestore(&sclp_lock, flags);
	return rc;
}

/* Deactivate SCLP interface. On success, new requests will be rejected,
 * events will no longer be dispatched. Return 0 on success, non-zero
 * otherwise. */
int
sclp_deactivate(void)
{
	unsigned long flags;
	int rc;

	spin_lock_irqsave(&sclp_lock, flags);
	/* Deactivate can only be called when active */
	if (sclp_activation_state != sclp_activation_state_active) {
		spin_unlock_irqrestore(&sclp_lock, flags);
		return -EINVAL;
	}
	sclp_activation_state = sclp_activation_state_deactivating;
	spin_unlock_irqrestore(&sclp_lock, flags);
	rc = sclp_init_mask(0);
	spin_lock_irqsave(&sclp_lock, flags);
	if (rc == 0)
		sclp_activation_state = sclp_activation_state_inactive;
	else
		sclp_activation_state = sclp_activation_state_active;
	spin_unlock_irqrestore(&sclp_lock, flags);
	return rc;
}

EXPORT_SYMBOL(sclp_deactivate);

/* Reactivate SCLP interface after sclp_deactivate. On success, new
 * requests will be accepted, events will be dispatched again. Return 0 on
 * success, non-zero otherwise. */
int
sclp_reactivate(void)
{
	unsigned long flags;
	int rc;

	spin_lock_irqsave(&sclp_lock, flags);
	/* Reactivate can only be called when inactive */
	if (sclp_activation_state != sclp_activation_state_inactive) {
		spin_unlock_irqrestore(&sclp_lock, flags);
		return -EINVAL;
	}
	sclp_activation_state = sclp_activation_state_activating;
	spin_unlock_irqrestore(&sclp_lock, flags);
	rc = sclp_init_mask(1);
	spin_lock_irqsave(&sclp_lock, flags);
	if (rc == 0)
		sclp_activation_state = sclp_activation_state_active;
	else
		sclp_activation_state = sclp_activation_state_inactive;
	spin_unlock_irqrestore(&sclp_lock, flags);
	return rc;
}

EXPORT_SYMBOL(sclp_reactivate);

/* Handler for external interruption used during initialization. Modify
 * request state to done. */
static void
sclp_check_handler(struct pt_regs *regs, __u16 code)
{
	u32 finished_sccb;

	finished_sccb = S390_lowcore.ext_params & 0xfffffff8;
	/* Is this the interrupt we are waiting for? */
	if (finished_sccb == 0)
		return;
	if (finished_sccb != (u32) (addr_t) sclp_init_sccb) {
		printk(KERN_WARNING SCLP_HEADER "unsolicited interrupt "
		       "for buffer at 0x%x\n", finished_sccb);
		return;
	}
	spin_lock(&sclp_lock);
	if (sclp_running_state == sclp_running_state_running) {
		sclp_init_req.status = SCLP_REQ_DONE;
		sclp_running_state = sclp_running_state_idle;
	}
	spin_unlock(&sclp_lock);
}

/* Initial init mask request timed out. Modify request state to failed. */
static void
sclp_check_timeout(unsigned long data)
{
	unsigned long flags;

	spin_lock_irqsave(&sclp_lock, flags);
	if (sclp_running_state == sclp_running_state_running) {
		sclp_init_req.status = SCLP_REQ_FAILED;
		sclp_running_state = sclp_running_state_idle;
	}
	spin_unlock_irqrestore(&sclp_lock, flags);
}

/* Perform a check of the SCLP interface. Return zero if the interface is
 * available and there are no pending requests from a previous instance.
 * Return non-zero otherwise. */
static int
sclp_check_interface(void)
{
	struct init_sccb *sccb;
	unsigned long flags;
	int retry;
	int rc;

	spin_lock_irqsave(&sclp_lock, flags);
	/* Prepare init mask command */
	rc = register_early_external_interrupt(0x2401, sclp_check_handler,
					       &ext_int_info_hwc);
	if (rc) {
		spin_unlock_irqrestore(&sclp_lock, flags);
		return rc;
	}
	for (retry = 0; retry <= SCLP_INIT_RETRY; retry++) {
		__sclp_make_init_req(0, 0);
		sccb = (struct init_sccb *) sclp_init_req.sccb;
		rc = service_call(sclp_init_req.command, sccb);
		if (rc == -EIO)
			break;
		sclp_init_req.status = SCLP_REQ_RUNNING;
		sclp_running_state = sclp_running_state_running;
		__sclp_set_request_timer(SCLP_RETRY_INTERVAL * HZ,
					 sclp_check_timeout, 0);
		spin_unlock_irqrestore(&sclp_lock, flags);
		/* Enable service-signal interruption - needs to happen
		 * with IRQs enabled. */
		ctl_set_bit(0, 9);
		/* Wait for signal from interrupt or timeout */
		sclp_sync_wait();
		/* Disable service-signal interruption - needs to happen
		 * with IRQs enabled. */
		ctl_clear_bit(0,9);
		spin_lock_irqsave(&sclp_lock, flags);
		del_timer(&sclp_request_timer);
		if (sclp_init_req.status == SCLP_REQ_DONE &&
		    sccb->header.response_code == 0x20) {
			rc = 0;
			break;
		} else
			rc = -EBUSY;
	}
	unregister_early_external_interrupt(0x2401, sclp_check_handler,
					    &ext_int_info_hwc);
	spin_unlock_irqrestore(&sclp_lock, flags);
	return rc;
}

/* Reboot event handler. Reset send and receive mask to prevent pending SCLP
 * events from interfering with rebooted system. */
static int
sclp_reboot_event(struct notifier_block *this, unsigned long event, void *ptr)
{
	sclp_deactivate();
	return NOTIFY_DONE;
}

static struct notifier_block sclp_reboot_notifier = {
	.notifier_call = sclp_reboot_event
};

/* Initialize SCLP driver. Return zero if driver is operational, non-zero
 * otherwise. */
static int
sclp_init(void)
{
	unsigned long flags;
	int rc;

	if (!MACHINE_HAS_SCLP)
		return -ENODEV;
	spin_lock_irqsave(&sclp_lock, flags);
	/* Check for previous or running initialization */
	if (sclp_init_state != sclp_init_state_uninitialized) {
		spin_unlock_irqrestore(&sclp_lock, flags);
		return 0;
	}
	sclp_init_state = sclp_init_state_initializing;
	/* Set up variables */
	INIT_LIST_HEAD(&sclp_req_queue);
	INIT_LIST_HEAD(&sclp_reg_list);
	list_add(&sclp_state_change_event.list, &sclp_reg_list);
	init_timer(&sclp_request_timer);
	/* Check interface */
	spin_unlock_irqrestore(&sclp_lock, flags);
	rc = sclp_check_interface();
	spin_lock_irqsave(&sclp_lock, flags);
	if (rc) {
		sclp_init_state = sclp_init_state_uninitialized;
		spin_unlock_irqrestore(&sclp_lock, flags);
		return rc;
	}
	/* Register reboot handler */
	rc = register_reboot_notifier(&sclp_reboot_notifier);
	if (rc) {
		sclp_init_state = sclp_init_state_uninitialized;
		spin_unlock_irqrestore(&sclp_lock, flags);
		return rc;
	}
	/* Register interrupt handler */
	rc = register_early_external_interrupt(0x2401, sclp_interrupt_handler,
					       &ext_int_info_hwc);
	if (rc) {
		unregister_reboot_notifier(&sclp_reboot_notifier);
		sclp_init_state = sclp_init_state_uninitialized;
		spin_unlock_irqrestore(&sclp_lock, flags);
		return rc;
	}
	sclp_init_state = sclp_init_state_initialized;
	spin_unlock_irqrestore(&sclp_lock, flags);
	/* Enable service-signal external interruption - needs to happen with
	 * IRQs enabled. */
	ctl_set_bit(0, 9);
	sclp_init_mask(1);
	return 0;
}