aboutsummaryrefslogtreecommitdiff
path: root/drivers/nvdimm/bus.c
blob: 7e2c43f701bc451463c5273ed3a5a1e49f6be15f (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
/*
 * Copyright(c) 2013-2015 Intel Corporation. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/vmalloc.h>
#include <linux/uaccess.h>
#include <linux/module.h>
#include <linux/blkdev.h>
#include <linux/fcntl.h>
#include <linux/async.h>
#include <linux/genhd.h>
#include <linux/ndctl.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/io.h>
#include <linux/mm.h>
#include <linux/nd.h>
#include "nd-core.h"
#include "nd.h"

int nvdimm_major;
static int nvdimm_bus_major;
static struct class *nd_class;

static int to_nd_device_type(struct device *dev)
{
	if (is_nvdimm(dev))
		return ND_DEVICE_DIMM;
	else if (is_nd_pmem(dev))
		return ND_DEVICE_REGION_PMEM;
	else if (is_nd_blk(dev))
		return ND_DEVICE_REGION_BLK;
	else if (is_nd_pmem(dev->parent) || is_nd_blk(dev->parent))
		return nd_region_to_nstype(to_nd_region(dev->parent));

	return 0;
}

static int nvdimm_bus_uevent(struct device *dev, struct kobj_uevent_env *env)
{
	/*
	 * Ensure that region devices always have their numa node set as
	 * early as possible.
	 */
	if (is_nd_pmem(dev) || is_nd_blk(dev))
		set_dev_node(dev, to_nd_region(dev)->numa_node);
	return add_uevent_var(env, "MODALIAS=" ND_DEVICE_MODALIAS_FMT,
			to_nd_device_type(dev));
}

static int nvdimm_bus_match(struct device *dev, struct device_driver *drv)
{
	struct nd_device_driver *nd_drv = to_nd_device_driver(drv);

	return test_bit(to_nd_device_type(dev), &nd_drv->type);
}

static struct module *to_bus_provider(struct device *dev)
{
	/* pin bus providers while regions are enabled */
	if (is_nd_pmem(dev) || is_nd_blk(dev)) {
		struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(dev);

		return nvdimm_bus->module;
	}
	return NULL;
}

static void nvdimm_bus_probe_start(struct nvdimm_bus *nvdimm_bus)
{
	nvdimm_bus_lock(&nvdimm_bus->dev);
	nvdimm_bus->probe_active++;
	nvdimm_bus_unlock(&nvdimm_bus->dev);
}

static void nvdimm_bus_probe_end(struct nvdimm_bus *nvdimm_bus)
{
	nvdimm_bus_lock(&nvdimm_bus->dev);
	if (--nvdimm_bus->probe_active == 0)
		wake_up(&nvdimm_bus->probe_wait);
	nvdimm_bus_unlock(&nvdimm_bus->dev);
}

static int nvdimm_bus_probe(struct device *dev)
{
	struct nd_device_driver *nd_drv = to_nd_device_driver(dev->driver);
	struct module *provider = to_bus_provider(dev);
	struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(dev);
	int rc;

	if (!try_module_get(provider))
		return -ENXIO;

	nvdimm_bus_probe_start(nvdimm_bus);
	rc = nd_drv->probe(dev);
	if (rc == 0)
		nd_region_probe_success(nvdimm_bus, dev);
	else
		nd_region_disable(nvdimm_bus, dev);
	nvdimm_bus_probe_end(nvdimm_bus);

	dev_dbg(&nvdimm_bus->dev, "%s.probe(%s) = %d\n", dev->driver->name,
			dev_name(dev), rc);

	if (rc != 0)
		module_put(provider);
	return rc;
}

static int nvdimm_bus_remove(struct device *dev)
{
	struct nd_device_driver *nd_drv = to_nd_device_driver(dev->driver);
	struct module *provider = to_bus_provider(dev);
	struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(dev);
	int rc;

	rc = nd_drv->remove(dev);
	nd_region_disable(nvdimm_bus, dev);

	dev_dbg(&nvdimm_bus->dev, "%s.remove(%s) = %d\n", dev->driver->name,
			dev_name(dev), rc);
	module_put(provider);
	return rc;
}

static struct bus_type nvdimm_bus_type = {
	.name = "nd",
	.uevent = nvdimm_bus_uevent,
	.match = nvdimm_bus_match,
	.probe = nvdimm_bus_probe,
	.remove = nvdimm_bus_remove,
};

static ASYNC_DOMAIN_EXCLUSIVE(nd_async_domain);

void nd_synchronize(void)
{
	async_synchronize_full_domain(&nd_async_domain);
}
EXPORT_SYMBOL_GPL(nd_synchronize);

static void nd_async_device_register(void *d, async_cookie_t cookie)
{
	struct device *dev = d;

	if (device_add(dev) != 0) {
		dev_err(dev, "%s: failed\n", __func__);
		put_device(dev);
	}
	put_device(dev);
}

static void nd_async_device_unregister(void *d, async_cookie_t cookie)
{
	struct device *dev = d;

	/* flush bus operations before delete */
	nvdimm_bus_lock(dev);
	nvdimm_bus_unlock(dev);

	device_unregister(dev);
	put_device(dev);
}

void __nd_device_register(struct device *dev)
{
	dev->bus = &nvdimm_bus_type;
	get_device(dev);
	async_schedule_domain(nd_async_device_register, dev,
			&nd_async_domain);
}

void nd_device_register(struct device *dev)
{
	device_initialize(dev);
	__nd_device_register(dev);
}
EXPORT_SYMBOL(nd_device_register);

void nd_device_unregister(struct device *dev, enum nd_async_mode mode)
{
	switch (mode) {
	case ND_ASYNC:
		get_device(dev);
		async_schedule_domain(nd_async_device_unregister, dev,
				&nd_async_domain);
		break;
	case ND_SYNC:
		nd_synchronize();
		device_unregister(dev);
		break;
	}
}
EXPORT_SYMBOL(nd_device_unregister);

/**
 * __nd_driver_register() - register a region or a namespace driver
 * @nd_drv: driver to register
 * @owner: automatically set by nd_driver_register() macro
 * @mod_name: automatically set by nd_driver_register() macro
 */
int __nd_driver_register(struct nd_device_driver *nd_drv, struct module *owner,
		const char *mod_name)
{
	struct device_driver *drv = &nd_drv->drv;

	if (!nd_drv->type) {
		pr_debug("driver type bitmask not set (%pf)\n",
				__builtin_return_address(0));
		return -EINVAL;
	}

	if (!nd_drv->probe || !nd_drv->remove) {
		pr_debug("->probe() and ->remove() must be specified\n");
		return -EINVAL;
	}

	drv->bus = &nvdimm_bus_type;
	drv->owner = owner;
	drv->mod_name = mod_name;

	return driver_register(drv);
}
EXPORT_SYMBOL(__nd_driver_register);

int nvdimm_revalidate_disk(struct gendisk *disk)
{
	struct device *dev = disk->driverfs_dev;
	struct nd_region *nd_region = to_nd_region(dev->parent);
	const char *pol = nd_region->ro ? "only" : "write";

	if (nd_region->ro == get_disk_ro(disk))
		return 0;

	dev_info(dev, "%s read-%s, marking %s read-%s\n",
			dev_name(&nd_region->dev), pol, disk->disk_name, pol);
	set_disk_ro(disk, nd_region->ro);

	return 0;

}
EXPORT_SYMBOL(nvdimm_revalidate_disk);

static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
		char *buf)
{
	return sprintf(buf, ND_DEVICE_MODALIAS_FMT "\n",
			to_nd_device_type(dev));
}
static DEVICE_ATTR_RO(modalias);

static ssize_t devtype_show(struct device *dev, struct device_attribute *attr,
		char *buf)
{
	return sprintf(buf, "%s\n", dev->type->name);
}
static DEVICE_ATTR_RO(devtype);

static struct attribute *nd_device_attributes[] = {
	&dev_attr_modalias.attr,
	&dev_attr_devtype.attr,
	NULL,
};

/**
 * nd_device_attribute_group - generic attributes for all devices on an nd bus
 */
struct attribute_group nd_device_attribute_group = {
	.attrs = nd_device_attributes,
};
EXPORT_SYMBOL_GPL(nd_device_attribute_group);

static ssize_t numa_node_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	return sprintf(buf, "%d\n", dev_to_node(dev));
}
static DEVICE_ATTR_RO(numa_node);

static struct attribute *nd_numa_attributes[] = {
	&dev_attr_numa_node.attr,
	NULL,
};

static umode_t nd_numa_attr_visible(struct kobject *kobj, struct attribute *a,
		int n)
{
	if (!IS_ENABLED(CONFIG_NUMA))
		return 0;

	return a->mode;
}

/**
 * nd_numa_attribute_group - NUMA attributes for all devices on an nd bus
 */
struct attribute_group nd_numa_attribute_group = {
	.attrs = nd_numa_attributes,
	.is_visible = nd_numa_attr_visible,
};
EXPORT_SYMBOL_GPL(nd_numa_attribute_group);

int nvdimm_bus_create_ndctl(struct nvdimm_bus *nvdimm_bus)
{
	dev_t devt = MKDEV(nvdimm_bus_major, nvdimm_bus->id);
	struct device *dev;

	dev = device_create(nd_class, &nvdimm_bus->dev, devt, nvdimm_bus,
			"ndctl%d", nvdimm_bus->id);

	if (IS_ERR(dev)) {
		dev_dbg(&nvdimm_bus->dev, "failed to register ndctl%d: %ld\n",
				nvdimm_bus->id, PTR_ERR(dev));
		return PTR_ERR(dev);
	}
	return 0;
}

void nvdimm_bus_destroy_ndctl(struct nvdimm_bus *nvdimm_bus)
{
	device_destroy(nd_class, MKDEV(nvdimm_bus_major, nvdimm_bus->id));
}

static const struct nd_cmd_desc __nd_cmd_dimm_descs[] = {
	[ND_CMD_IMPLEMENTED] = { },
	[ND_CMD_SMART] = {
		.out_num = 2,
		.out_sizes = { 4, 8, },
	},
	[ND_CMD_SMART_THRESHOLD] = {
		.out_num = 2,
		.out_sizes = { 4, 8, },
	},
	[ND_CMD_DIMM_FLAGS] = {
		.out_num = 2,
		.out_sizes = { 4, 4 },
	},
	[ND_CMD_GET_CONFIG_SIZE] = {
		.out_num = 3,
		.out_sizes = { 4, 4, 4, },
	},
	[ND_CMD_GET_CONFIG_DATA] = {
		.in_num = 2,
		.in_sizes = { 4, 4, },
		.out_num = 2,
		.out_sizes = { 4, UINT_MAX, },
	},
	[ND_CMD_SET_CONFIG_DATA] = {
		.in_num = 3,
		.in_sizes = { 4, 4, UINT_MAX, },
		.out_num = 1,
		.out_sizes = { 4, },
	},
	[ND_CMD_VENDOR] = {
		.in_num = 3,
		.in_sizes = { 4, 4, UINT_MAX, },
		.out_num = 3,
		.out_sizes = { 4, 4, UINT_MAX, },
	},
};

const struct nd_cmd_desc *nd_cmd_dimm_desc(int cmd)
{
	if (cmd < ARRAY_SIZE(__nd_cmd_dimm_descs))
		return &__nd_cmd_dimm_descs[cmd];
	return NULL;
}
EXPORT_SYMBOL_GPL(nd_cmd_dimm_desc);

static const struct nd_cmd_desc __nd_cmd_bus_descs[] = {
	[ND_CMD_IMPLEMENTED] = { },
	[ND_CMD_ARS_CAP] = {
		.in_num = 2,
		.in_sizes = { 8, 8, },
		.out_num = 2,
		.out_sizes = { 4, 4, },
	},
	[ND_CMD_ARS_START] = {
		.in_num = 4,
		.in_sizes = { 8, 8, 2, 6, },
		.out_num = 1,
		.out_sizes = { 4, },
	},
	[ND_CMD_ARS_STATUS] = {
		.out_num = 2,
		.out_sizes = { 4, UINT_MAX, },
	},
};

const struct nd_cmd_desc *nd_cmd_bus_desc(int cmd)
{
	if (cmd < ARRAY_SIZE(__nd_cmd_bus_descs))
		return &__nd_cmd_bus_descs[cmd];
	return NULL;
}
EXPORT_SYMBOL_GPL(nd_cmd_bus_desc);

u32 nd_cmd_in_size(struct nvdimm *nvdimm, int cmd,
		const struct nd_cmd_desc *desc, int idx, void *buf)
{
	if (idx >= desc->in_num)
		return UINT_MAX;

	if (desc->in_sizes[idx] < UINT_MAX)
		return desc->in_sizes[idx];

	if (nvdimm && cmd == ND_CMD_SET_CONFIG_DATA && idx == 2) {
		struct nd_cmd_set_config_hdr *hdr = buf;

		return hdr->in_length;
	} else if (nvdimm && cmd == ND_CMD_VENDOR && idx == 2) {
		struct nd_cmd_vendor_hdr *hdr = buf;

		return hdr->in_length;
	}

	return UINT_MAX;
}
EXPORT_SYMBOL_GPL(nd_cmd_in_size);

u32 nd_cmd_out_size(struct nvdimm *nvdimm, int cmd,
		const struct nd_cmd_desc *desc, int idx, const u32 *in_field,
		const u32 *out_field)
{
	if (idx >= desc->out_num)
		return UINT_MAX;

	if (desc->out_sizes[idx] < UINT_MAX)
		return desc->out_sizes[idx];

	if (nvdimm && cmd == ND_CMD_GET_CONFIG_DATA && idx == 1)
		return in_field[1];
	else if (nvdimm && cmd == ND_CMD_VENDOR && idx == 2)
		return out_field[1];
	else if (!nvdimm && cmd == ND_CMD_ARS_STATUS && idx == 1)
		return ND_CMD_ARS_STATUS_MAX;

	return UINT_MAX;
}
EXPORT_SYMBOL_GPL(nd_cmd_out_size);

void wait_nvdimm_bus_probe_idle(struct device *dev)
{
	struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(dev);

	do {
		if (nvdimm_bus->probe_active == 0)
			break;
		nvdimm_bus_unlock(&nvdimm_bus->dev);
		wait_event(nvdimm_bus->probe_wait,
				nvdimm_bus->probe_active == 0);
		nvdimm_bus_lock(&nvdimm_bus->dev);
	} while (true);
}

/* set_config requires an idle interleave set */
static int nd_cmd_clear_to_send(struct nvdimm *nvdimm, unsigned int cmd)
{
	struct nvdimm_bus *nvdimm_bus;

	if (!nvdimm || cmd != ND_CMD_SET_CONFIG_DATA)
		return 0;

	nvdimm_bus = walk_to_nvdimm_bus(&nvdimm->dev);
	wait_nvdimm_bus_probe_idle(&nvdimm_bus->dev);

	if (atomic_read(&nvdimm->busy))
		return -EBUSY;
	return 0;
}

static int __nd_ioctl(struct nvdimm_bus *nvdimm_bus, struct nvdimm *nvdimm,
		int read_only, unsigned int ioctl_cmd, unsigned long arg)
{
	struct nvdimm_bus_descriptor *nd_desc = nvdimm_bus->nd_desc;
	size_t buf_len = 0, in_len = 0, out_len = 0;
	static char out_env[ND_CMD_MAX_ENVELOPE];
	static char in_env[ND_CMD_MAX_ENVELOPE];
	const struct nd_cmd_desc *desc = NULL;
	unsigned int cmd = _IOC_NR(ioctl_cmd);
	void __user *p = (void __user *) arg;
	struct device *dev = &nvdimm_bus->dev;
	const char *cmd_name, *dimm_name;
	unsigned long dsm_mask;
	void *buf;
	int rc, i;

	if (nvdimm) {
		desc = nd_cmd_dimm_desc(cmd);
		cmd_name = nvdimm_cmd_name(cmd);
		dsm_mask = nvdimm->dsm_mask ? *(nvdimm->dsm_mask) : 0;
		dimm_name = dev_name(&nvdimm->dev);
	} else {
		desc = nd_cmd_bus_desc(cmd);
		cmd_name = nvdimm_bus_cmd_name(cmd);
		dsm_mask = nd_desc->dsm_mask;
		dimm_name = "bus";
	}

	if (!desc || (desc->out_num + desc->in_num == 0) ||
			!test_bit(cmd, &dsm_mask))
		return -ENOTTY;

	/* fail write commands (when read-only) */
	if (read_only)
		switch (ioctl_cmd) {
		case ND_IOCTL_VENDOR:
		case ND_IOCTL_SET_CONFIG_DATA:
		case ND_IOCTL_ARS_START:
			dev_dbg(&nvdimm_bus->dev, "'%s' command while read-only.\n",
					nvdimm ? nvdimm_cmd_name(cmd)
					: nvdimm_bus_cmd_name(cmd));
			return -EPERM;
		default:
			break;
		}

	/* process an input envelope */
	for (i = 0; i < desc->in_num; i++) {
		u32 in_size, copy;

		in_size = nd_cmd_in_size(nvdimm, cmd, desc, i, in_env);
		if (in_size == UINT_MAX) {
			dev_err(dev, "%s:%s unknown input size cmd: %s field: %d\n",
					__func__, dimm_name, cmd_name, i);
			return -ENXIO;
		}
		if (in_len < sizeof(in_env))
			copy = min_t(u32, sizeof(in_env) - in_len, in_size);
		else
			copy = 0;
		if (copy && copy_from_user(&in_env[in_len], p + in_len, copy))
			return -EFAULT;
		in_len += in_size;
	}

	/* process an output envelope */
	for (i = 0; i < desc->out_num; i++) {
		u32 out_size = nd_cmd_out_size(nvdimm, cmd, desc, i,
				(u32 *) in_env, (u32 *) out_env);
		u32 copy;

		if (out_size == UINT_MAX) {
			dev_dbg(dev, "%s:%s unknown output size cmd: %s field: %d\n",
					__func__, dimm_name, cmd_name, i);
			return -EFAULT;
		}
		if (out_len < sizeof(out_env))
			copy = min_t(u32, sizeof(out_env) - out_len, out_size);
		else
			copy = 0;
		if (copy && copy_from_user(&out_env[out_len],
					p + in_len + out_len, copy))
			return -EFAULT;
		out_len += out_size;
	}

	buf_len = out_len + in_len;
	if (buf_len > ND_IOCTL_MAX_BUFLEN) {
		dev_dbg(dev, "%s:%s cmd: %s buf_len: %zu > %d\n", __func__,
				dimm_name, cmd_name, buf_len,
				ND_IOCTL_MAX_BUFLEN);
		return -EINVAL;
	}

	buf = vmalloc(buf_len);
	if (!buf)
		return -ENOMEM;

	if (copy_from_user(buf, p, buf_len)) {
		rc = -EFAULT;
		goto out;
	}

	nvdimm_bus_lock(&nvdimm_bus->dev);
	rc = nd_cmd_clear_to_send(nvdimm, cmd);
	if (rc)
		goto out_unlock;

	rc = nd_desc->ndctl(nd_desc, nvdimm, cmd, buf, buf_len);
	if (rc < 0)
		goto out_unlock;
	if (copy_to_user(p, buf, buf_len))
		rc = -EFAULT;
 out_unlock:
	nvdimm_bus_unlock(&nvdimm_bus->dev);
 out:
	vfree(buf);
	return rc;
}

static long nd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
	long id = (long) file->private_data;
	int rc = -ENXIO, read_only;
	struct nvdimm_bus *nvdimm_bus;

	read_only = (O_RDWR != (file->f_flags & O_ACCMODE));
	mutex_lock(&nvdimm_bus_list_mutex);
	list_for_each_entry(nvdimm_bus, &nvdimm_bus_list, list) {
		if (nvdimm_bus->id == id) {
			rc = __nd_ioctl(nvdimm_bus, NULL, read_only, cmd, arg);
			break;
		}
	}
	mutex_unlock(&nvdimm_bus_list_mutex);

	return rc;
}

static int match_dimm(struct device *dev, void *data)
{
	long id = (long) data;

	if (is_nvdimm(dev)) {
		struct nvdimm *nvdimm = to_nvdimm(dev);

		return nvdimm->id == id;
	}

	return 0;
}

static long nvdimm_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
	int rc = -ENXIO, read_only;
	struct nvdimm_bus *nvdimm_bus;

	read_only = (O_RDWR != (file->f_flags & O_ACCMODE));
	mutex_lock(&nvdimm_bus_list_mutex);
	list_for_each_entry(nvdimm_bus, &nvdimm_bus_list, list) {
		struct device *dev = device_find_child(&nvdimm_bus->dev,
				file->private_data, match_dimm);
		struct nvdimm *nvdimm;

		if (!dev)
			continue;

		nvdimm = to_nvdimm(dev);
		rc = __nd_ioctl(nvdimm_bus, nvdimm, read_only, cmd, arg);
		put_device(dev);
		break;
	}
	mutex_unlock(&nvdimm_bus_list_mutex);

	return rc;
}

static int nd_open(struct inode *inode, struct file *file)
{
	long minor = iminor(inode);

	file->private_data = (void *) minor;
	return 0;
}

static const struct file_operations nvdimm_bus_fops = {
	.owner = THIS_MODULE,
	.open = nd_open,
	.unlocked_ioctl = nd_ioctl,
	.compat_ioctl = nd_ioctl,
	.llseek = noop_llseek,
};

static const struct file_operations nvdimm_fops = {
	.owner = THIS_MODULE,
	.open = nd_open,
	.unlocked_ioctl = nvdimm_ioctl,
	.compat_ioctl = nvdimm_ioctl,
	.llseek = noop_llseek,
};

int __init nvdimm_bus_init(void)
{
	int rc;

	rc = bus_register(&nvdimm_bus_type);
	if (rc)
		return rc;

	rc = register_chrdev(0, "ndctl", &nvdimm_bus_fops);
	if (rc < 0)
		goto err_bus_chrdev;
	nvdimm_bus_major = rc;

	rc = register_chrdev(0, "dimmctl", &nvdimm_fops);
	if (rc < 0)
		goto err_dimm_chrdev;
	nvdimm_major = rc;

	nd_class = class_create(THIS_MODULE, "nd");
	if (IS_ERR(nd_class)) {
		rc = PTR_ERR(nd_class);
		goto err_class;
	}

	return 0;

 err_class:
	unregister_chrdev(nvdimm_major, "dimmctl");
 err_dimm_chrdev:
	unregister_chrdev(nvdimm_bus_major, "ndctl");
 err_bus_chrdev:
	bus_unregister(&nvdimm_bus_type);

	return rc;
}

void nvdimm_bus_exit(void)
{
	class_destroy(nd_class);
	unregister_chrdev(nvdimm_bus_major, "ndctl");
	unregister_chrdev(nvdimm_major, "dimmctl");
	bus_unregister(&nvdimm_bus_type);
}