aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/s390/cio/css.c
blob: 555119cacc279c07c59372892fba6d4983153a13 (plain) (blame)
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
/*
 *  drivers/s390/cio/css.c
 *  driver for channel subsystem
 *   $Revision: 1.85 $
 *
 *    Copyright (C) 2002 IBM Deutschland Entwicklung GmbH,
 *			 IBM Corporation
 *    Author(s): Arnd Bergmann (arndb@de.ibm.com)
 *		 Cornelia Huck (cohuck@de.ibm.com)
 */
#include <linux/module.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/list.h>

#include "css.h"
#include "cio.h"
#include "cio_debug.h"
#include "ioasm.h"
#include "chsc.h"

unsigned int highest_subchannel;
int need_rescan = 0;
int css_init_done = 0;

struct pgid global_pgid;
int css_characteristics_avail = 0;

struct device css_bus_device = {
	.bus_id = "css0",
};

static struct subchannel *
css_alloc_subchannel(int irq)
{
	struct subchannel *sch;
	int ret;

	sch = kmalloc (sizeof (*sch), GFP_KERNEL | GFP_DMA);
	if (sch == NULL)
		return ERR_PTR(-ENOMEM);
	ret = cio_validate_subchannel (sch, irq);
	if (ret < 0) {
		kfree(sch);
		return ERR_PTR(ret);
	}
	if (irq > highest_subchannel)
		highest_subchannel = irq;

	if (sch->st != SUBCHANNEL_TYPE_IO) {
		/* For now we ignore all non-io subchannels. */
		kfree(sch);
		return ERR_PTR(-EINVAL);
	}

	/* 
	 * Set intparm to subchannel address.
	 * This is fine even on 64bit since the subchannel is always located
	 * under 2G.
	 */
	sch->schib.pmcw.intparm = (__u32)(unsigned long)sch;
	ret = cio_modify(sch);
	if (ret) {
		kfree(sch);
		return ERR_PTR(ret);
	}
	return sch;
}

static void
css_free_subchannel(struct subchannel *sch)
{
	if (sch) {
		/* Reset intparm to zeroes. */
		sch->schib.pmcw.intparm = 0;
		cio_modify(sch);
		kfree(sch);
	}
	
}

static void
css_subchannel_release(struct device *dev)
{
	struct subchannel *sch;

	sch = to_subchannel(dev);
	if (!cio_is_console(sch->irq))
		kfree(sch);
}

extern int css_get_ssd_info(struct subchannel *sch);

static int
css_register_subchannel(struct subchannel *sch)
{
	int ret;

	/* Initialize the subchannel structure */
	sch->dev.parent = &css_bus_device;
	sch->dev.bus = &css_bus_type;
	sch->dev.release = &css_subchannel_release;
	
	/* make it known to the system */
	ret = device_register(&sch->dev);
	if (ret)
		printk (KERN_WARNING "%s: could not register %s\n",
			__func__, sch->dev.bus_id);
	else
		css_get_ssd_info(sch);
	return ret;
}

int
css_probe_device(int irq)
{
	int ret;
	struct subchannel *sch;

	sch = css_alloc_subchannel(irq);
	if (IS_ERR(sch))
		return PTR_ERR(sch);
	ret = css_register_subchannel(sch);
	if (ret)
		css_free_subchannel(sch);
	return ret;
}

static int
check_subchannel(struct device * dev, void * data)
{
	struct subchannel *sch;
	int irq = (unsigned long)data;

	sch = to_subchannel(dev);
	return (sch->irq == irq);
}

struct subchannel *
get_subchannel_by_schid(int irq)
{
	struct device *dev;

	dev = bus_find_device(&css_bus_type, NULL,
			      (void *)(unsigned long)irq, check_subchannel);

	return dev ? to_subchannel(dev) : NULL;
}


static inline int
css_get_subchannel_status(struct subchannel *sch, int schid)
{
	struct schib schib;
	int cc;

	cc = stsch(schid, &schib);
	if (cc)
		return CIO_GONE;
	if (!schib.pmcw.dnv)
		return CIO_GONE;
	if (sch && sch->schib.pmcw.dnv &&
	    (schib.pmcw.dev != sch->schib.pmcw.dev))
		return CIO_REVALIDATE;
	if (sch && !sch->lpm)
		return CIO_NO_PATH;
	return CIO_OPER;
}
	
static int
css_evaluate_subchannel(int irq, int slow)
{
	int event, ret, disc;
	struct subchannel *sch;
	unsigned long flags;

	sch = get_subchannel_by_schid(irq);
	disc = sch ? device_is_disconnected(sch) : 0;
	if (disc && slow) {
		if (sch)
			put_device(&sch->dev);
		return 0; /* Already processed. */
	}
	/*
	 * We've got a machine check, so running I/O won't get an interrupt.
	 * Kill any pending timers.
	 */
	if (sch)
		device_kill_pending_timer(sch);
	if (!disc && !slow) {
		if (sch)
			put_device(&sch->dev);
		return -EAGAIN; /* Will be done on the slow path. */
	}
	event = css_get_subchannel_status(sch, irq);
	CIO_MSG_EVENT(4, "Evaluating schid %04x, event %d, %s, %s path.\n",
		      irq, event, sch?(disc?"disconnected":"normal"):"unknown",
		      slow?"slow":"fast");
	switch (event) {
	case CIO_NO_PATH:
	case CIO_GONE:
		if (!sch) {
			/* Never used this subchannel. Ignore. */
			ret = 0;
			break;
		}
		if (disc && (event == CIO_NO_PATH)) {
			/*
			 * Uargh, hack again. Because we don't get a machine
			 * check on configure on, our path bookkeeping can
			 * be out of date here (it's fine while we only do
			 * logical varying or get chsc machine checks). We
			 * need to force reprobing or we might miss devices
			 * coming operational again. It won't do harm in real
			 * no path situations.
			 */
			spin_lock_irqsave(&sch->lock, flags);
			device_trigger_reprobe(sch);
			spin_unlock_irqrestore(&sch->lock, flags);
			ret = 0;
			break;
		}
		if (sch->driver && sch->driver->notify &&
		    sch->driver->notify(&sch->dev, event)) {
			cio_disable_subchannel(sch);
			device_set_disconnected(sch);
			ret = 0;
			break;
		}
		/*
		 * Unregister subchannel.
		 * The device will be killed automatically.
		 */
		cio_disable_subchannel(sch);
		device_unregister(&sch->dev);
		/* Reset intparm to zeroes. */
		sch->schib.pmcw.intparm = 0;
		cio_modify(sch);
		put_device(&sch->dev);
		ret = 0;
		break;
	case CIO_REVALIDATE:
		/* 
		 * Revalidation machine check. Sick.
		 * We don't notify the driver since we have to throw the device
		 * away in any case.
		 */
		if (!disc) {
			device_unregister(&sch->dev);
			/* Reset intparm to zeroes. */
			sch->schib.pmcw.intparm = 0;
			cio_modify(sch);
			put_device(&sch->dev);
			ret = css_probe_device(irq);
		} else {
			/*
			 * We can't immediately deregister the disconnected
			 * device since it might block.
			 */
			spin_lock_irqsave(&sch->lock, flags);
			device_trigger_reprobe(sch);
			spin_unlock_irqrestore(&sch->lock, flags);
			ret = 0;
		}
		break;
	case CIO_OPER:
		if (disc) {
			spin_lock_irqsave(&sch->lock, flags);
			/* Get device operational again. */
			device_trigger_reprobe(sch);
			spin_unlock_irqrestore(&sch->lock, flags);
		}
		ret = sch ? 0 : css_probe_device(irq);
		break;
	default:
		BUG();
		ret = 0;
	}
	return ret;
}

static void
css_rescan_devices(void)
{
	int irq, ret;

	for (irq = 0; irq < __MAX_SUBCHANNELS; irq++) {
		ret = css_evaluate_subchannel(irq, 1);
		/* No more memory. It doesn't make sense to continue. No
		 * panic because this can happen in midflight and just
		 * because we can't use a new device is no reason to crash
		 * the system. */
		if (ret == -ENOMEM)
			break;
		/* -ENXIO indicates that there are no more subchannels. */
		if (ret == -ENXIO)
			break;
	}
}

struct slow_subchannel {
	struct list_head slow_list;
	unsigned long schid;
};

static LIST_HEAD(slow_subchannels_head);
static DEFINE_SPINLOCK(slow_subchannel_lock);

static void
css_trigger_slow_path(void)
{
	CIO_TRACE_EVENT(4, "slowpath");

	if (need_rescan) {
		need_rescan = 0;
		css_rescan_devices();
		return;
	}

	spin_lock_irq(&slow_subchannel_lock);
	while (!list_empty(&slow_subchannels_head)) {
		struct slow_subchannel *slow_sch =
			list_entry(slow_subchannels_head.next,
				   struct slow_subchannel, slow_list);

		list_del_init(slow_subchannels_head.next);
		spin_unlock_irq(&slow_subchannel_lock);
		css_evaluate_subchannel(slow_sch->schid, 1);
		spin_lock_irq(&slow_subchannel_lock);
		kfree(slow_sch);
	}
	spin_unlock_irq(&slow_subchannel_lock);
}

typedef void (*workfunc)(void *);
DECLARE_WORK(slow_path_work, (workfunc)css_trigger_slow_path, NULL);
struct workqueue_struct *slow_path_wq;

/*
 * Rescan for new devices. FIXME: This is slow.
 * This function is called when we have lost CRWs due to overflows and we have
 * to do subchannel housekeeping.
 */
void
css_reiterate_subchannels(void)
{
	css_clear_subchannel_slow_list();
	need_rescan = 1;
}

/*
 * Called from the machine check handler for subchannel report words.
 */
int
css_process_crw(int irq)
{
	int ret;

	CIO_CRW_EVENT(2, "source is subchannel %04X\n", irq);

	if (need_rescan)
		/* We need to iterate all subchannels anyway. */
		return -EAGAIN;
	/* 
	 * Since we are always presented with IPI in the CRW, we have to
	 * use stsch() to find out if the subchannel in question has come
	 * or gone.
	 */
	ret = css_evaluate_subchannel(irq, 0);
	if (ret == -EAGAIN) {
		if (css_enqueue_subchannel_slow(irq)) {
			css_clear_subchannel_slow_list();
			need_rescan = 1;
		}
	}
	return ret;
}

static void __init
css_generate_pgid(void)
{
	/* Let's build our path group ID here. */
	if (css_characteristics_avail && css_general_characteristics.mcss)
		global_pgid.cpu_addr = 0x8000;
	else {
#ifdef CONFIG_SMP
		global_pgid.cpu_addr = hard_smp_processor_id();
#else
		global_pgid.cpu_addr = 0;
#endif
	}
	global_pgid.cpu_id = ((cpuid_t *) __LC_CPUID)->ident;
	global_pgid.cpu_model = ((cpuid_t *) __LC_CPUID)->machine;
	global_pgid.tod_high = (__u32) (get_clock() >> 32);
}

/*
 * Now that the driver core is running, we can setup our channel subsystem.
 * The struct subchannel's are created during probing (except for the
 * static console subchannel).
 */
static int __init
init_channel_subsystem (void)
{
	int ret, irq;

	if (chsc_determine_css_characteristics() == 0)
		css_characteristics_avail = 1;

	css_generate_pgid();

	if ((ret = bus_register(&css_bus_type)))
		goto out;
	if ((ret = device_register (&css_bus_device)))
		goto out_bus;

	css_init_done = 1;

	ctl_set_bit(6, 28);

	for (irq = 0; irq < __MAX_SUBCHANNELS; irq++) {
		struct subchannel *sch;

		if (cio_is_console(irq))
			sch = cio_get_console_subchannel();
		else {
			sch = css_alloc_subchannel(irq);
			if (IS_ERR(sch))
				ret = PTR_ERR(sch);
			else
				ret = 0;
			if (ret == -ENOMEM)
				panic("Out of memory in "
				      "init_channel_subsystem\n");
			/* -ENXIO: no more subchannels. */
			if (ret == -ENXIO)
				break;
			if (ret)
				continue;
		}
		/*
		 * We register ALL valid subchannels in ioinfo, even those
		 * that have been present before init_channel_subsystem.
		 * These subchannels can't have been registered yet (kmalloc
		 * not working) so we do it now. This is true e.g. for the
		 * console subchannel.
		 */
		css_register_subchannel(sch);
	}
	return 0;

out_bus:
	bus_unregister(&css_bus_type);
out:
	return ret;
}

/*
 * find a driver for a subchannel. They identify by the subchannel
 * type with the exception that the console subchannel driver has its own
 * subchannel type although the device is an i/o subchannel
 */
static int
css_bus_match (struct device *dev, struct device_driver *drv)
{
	struct subchannel *sch = container_of (dev, struct subchannel, dev);
	struct css_driver *driver = container_of (drv, struct css_driver, drv);

	if (sch->st == driver->subchannel_type)
		return 1;

	return 0;
}

struct bus_type css_bus_type = {
	.name  = "css",
	.match = &css_bus_match,
};

subsys_initcall(init_channel_subsystem);

/*
 * Register root devices for some drivers. The release function must not be
 * in the device drivers, so we do it here.
 */
static void
s390_root_dev_release(struct device *dev)
{
	kfree(dev);
}

struct device *
s390_root_dev_register(const char *name)
{
	struct device *dev;
	int ret;

	if (!strlen(name))
		return ERR_PTR(-EINVAL);
	dev = kmalloc(sizeof(struct device), GFP_KERNEL);
	if (!dev)
		return ERR_PTR(-ENOMEM);
	memset(dev, 0, sizeof(struct device));
	strncpy(dev->bus_id, name, min(strlen(name), (size_t)BUS_ID_SIZE));
	dev->release = s390_root_dev_release;
	ret = device_register(dev);
	if (ret) {
		kfree(dev);
		return ERR_PTR(ret);
	}
	return dev;
}

void
s390_root_dev_unregister(struct device *dev)
{
	if (dev)
		device_unregister(dev);
}

int
css_enqueue_subchannel_slow(unsigned long schid)
{
	struct slow_subchannel *new_slow_sch;
	unsigned long flags;

	new_slow_sch = kmalloc(sizeof(struct slow_subchannel), GFP_ATOMIC);
	if (!new_slow_sch)
		return -ENOMEM;
	memset(new_slow_sch, 0, sizeof(struct slow_subchannel));
	new_slow_sch->schid = schid;
	spin_lock_irqsave(&slow_subchannel_lock, flags);
	list_add_tail(&new_slow_sch->slow_list, &slow_subchannels_head);
	spin_unlock_irqrestore(&slow_subchannel_lock, flags);
	return 0;
}

void
css_clear_subchannel_slow_list(void)
{
	unsigned long flags;

	spin_lock_irqsave(&slow_subchannel_lock, flags);
	while (!list_empty(&slow_subchannels_head)) {
		struct slow_subchannel *slow_sch =
			list_entry(slow_subchannels_head.next,
				   struct slow_subchannel, slow_list);

		list_del_init(slow_subchannels_head.next);
		kfree(slow_sch);
	}
	spin_unlock_irqrestore(&slow_subchannel_lock, flags);
}



int
css_slow_subchannels_exist(void)
{
	return (!list_empty(&slow_subchannels_head));
}

MODULE_LICENSE("GPL");
EXPORT_SYMBOL(css_bus_type);
EXPORT_SYMBOL(s390_root_dev_register);
EXPORT_SYMBOL(s390_root_dev_unregister);
EXPORT_SYMBOL_GPL(css_characteristics_avail);