summaryrefslogtreecommitdiffstats
path: root/drivers/hv/vmbus_drv.c
blob: f40dd57bbec1cc037e6fc13f92a41521e3f8971f (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
/*
 * Copyright (c) 2009, Microsoft Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope 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.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
 * Place - Suite 330, Boston, MA 02111-1307 USA.
 *
 * Authors:
 *   Haiyang Zhang <haiyangz@microsoft.com>
 *   Hank Janssen  <hjanssen@microsoft.com>
 *   K. Y. Srinivasan <kys@microsoft.com>
 *
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/init.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/irq.h>
#include <linux/interrupt.h>
#include <linux/sysctl.h>
#include <linux/slab.h>
#include <linux/acpi.h>
#include <acpi/acpi_bus.h>
#include <linux/completion.h>
#include <linux/hyperv.h>
#include <asm/hyperv.h>
#include "hyperv_vmbus.h"


static struct acpi_device  *hv_acpi_dev;

static struct tasklet_struct msg_dpc;
static struct tasklet_struct event_dpc;
static struct completion probe_event;
static int irq;

struct hv_device_info {
	u32 chn_id;
	u32 chn_state;
	uuid_le chn_type;
	uuid_le chn_instance;

	u32 monitor_id;
	u32 server_monitor_pending;
	u32 server_monitor_latency;
	u32 server_monitor_conn_id;
	u32 client_monitor_pending;
	u32 client_monitor_latency;
	u32 client_monitor_conn_id;

	struct hv_dev_port_info inbound;
	struct hv_dev_port_info outbound;
};

static int vmbus_exists(void)
{
	if (hv_acpi_dev == NULL)
		return -ENODEV;

	return 0;
}


static void get_channel_info(struct hv_device *device,
			     struct hv_device_info *info)
{
	struct vmbus_channel_debug_info debug_info;

	if (!device->channel)
		return;

	vmbus_get_debug_info(device->channel, &debug_info);

	info->chn_id = debug_info.relid;
	info->chn_state = debug_info.state;
	memcpy(&info->chn_type, &debug_info.interfacetype,
	       sizeof(uuid_le));
	memcpy(&info->chn_instance, &debug_info.interface_instance,
	       sizeof(uuid_le));

	info->monitor_id = debug_info.monitorid;

	info->server_monitor_pending = debug_info.servermonitor_pending;
	info->server_monitor_latency = debug_info.servermonitor_latency;
	info->server_monitor_conn_id = debug_info.servermonitor_connectionid;

	info->client_monitor_pending = debug_info.clientmonitor_pending;
	info->client_monitor_latency = debug_info.clientmonitor_latency;
	info->client_monitor_conn_id = debug_info.clientmonitor_connectionid;

	info->inbound.int_mask = debug_info.inbound.current_interrupt_mask;
	info->inbound.read_idx = debug_info.inbound.current_read_index;
	info->inbound.write_idx = debug_info.inbound.current_write_index;
	info->inbound.bytes_avail_toread =
		debug_info.inbound.bytes_avail_toread;
	info->inbound.bytes_avail_towrite =
		debug_info.inbound.bytes_avail_towrite;

	info->outbound.int_mask =
		debug_info.outbound.current_interrupt_mask;
	info->outbound.read_idx = debug_info.outbound.current_read_index;
	info->outbound.write_idx = debug_info.outbound.current_write_index;
	info->outbound.bytes_avail_toread =
		debug_info.outbound.bytes_avail_toread;
	info->outbound.bytes_avail_towrite =
		debug_info.outbound.bytes_avail_towrite;
}

#define VMBUS_ALIAS_LEN ((sizeof((struct hv_vmbus_device_id *)0)->guid) * 2)
static void print_alias_name(struct hv_device *hv_dev, char *alias_name)
{
	int i;
	for (i = 0; i < VMBUS_ALIAS_LEN; i += 2)
		sprintf(&alias_name[i], "%02x", hv_dev->dev_type.b[i/2]);
}

/*
 * vmbus_show_device_attr - Show the device attribute in sysfs.
 *
 * This is invoked when user does a
 * "cat /sys/bus/vmbus/devices/<busdevice>/<attr name>"
 */
static ssize_t vmbus_show_device_attr(struct device *dev,
				      struct device_attribute *dev_attr,
				      char *buf)
{
	struct hv_device *hv_dev = device_to_hv_device(dev);
	struct hv_device_info *device_info;
	char alias_name[VMBUS_ALIAS_LEN + 1];
	int ret = 0;

	device_info = kzalloc(sizeof(struct hv_device_info), GFP_KERNEL);
	if (!device_info)
		return ret;

	get_channel_info(hv_dev, device_info);

	if (!strcmp(dev_attr->attr.name, "class_id")) {
		ret = sprintf(buf, "{%pUl}\n", device_info->chn_type.b);
	} else if (!strcmp(dev_attr->attr.name, "device_id")) {
		ret = sprintf(buf, "{%pUl}\n", device_info->chn_instance.b);
	} else if (!strcmp(dev_attr->attr.name, "modalias")) {
		print_alias_name(hv_dev, alias_name);
		ret = sprintf(buf, "vmbus:%s\n", alias_name);
	} else if (!strcmp(dev_attr->attr.name, "state")) {
		ret = sprintf(buf, "%d\n", device_info->chn_state);
	} else if (!strcmp(dev_attr->attr.name, "id")) {
		ret = sprintf(buf, "%d\n", device_info->chn_id);
	} else if (!strcmp(dev_attr->attr.name, "out_intr_mask")) {
		ret = sprintf(buf, "%d\n", device_info->outbound.int_mask);
	} else if (!strcmp(dev_attr->attr.name, "out_read_index")) {
		ret = sprintf(buf, "%d\n", device_info->outbound.read_idx);
	} else if (!strcmp(dev_attr->attr.name, "out_write_index")) {
		ret = sprintf(buf, "%d\n", device_info->outbound.write_idx);
	} else if (!strcmp(dev_attr->attr.name, "out_read_bytes_avail")) {
		ret = sprintf(buf, "%d\n",
			       device_info->outbound.bytes_avail_toread);
	} else if (!strcmp(dev_attr->attr.name, "out_write_bytes_avail")) {
		ret = sprintf(buf, "%d\n",
			       device_info->outbound.bytes_avail_towrite);
	} else if (!strcmp(dev_attr->attr.name, "in_intr_mask")) {
		ret = sprintf(buf, "%d\n", device_info->inbound.int_mask);
	} else if (!strcmp(dev_attr->attr.name, "in_read_index")) {
		ret = sprintf(buf, "%d\n", device_info->inbound.read_idx);
	} else if (!strcmp(dev_attr->attr.name, "in_write_index")) {
		ret = sprintf(buf, "%d\n", device_info->inbound.write_idx);
	} else if (!strcmp(dev_attr->attr.name, "in_read_bytes_avail")) {
		ret = sprintf(buf, "%d\n",
			       device_info->inbound.bytes_avail_toread);
	} else if (!strcmp(dev_attr->attr.name, "in_write_bytes_avail")) {
		ret = sprintf(buf, "%d\n",
			       device_info->inbound.bytes_avail_towrite);
	} else if (!strcmp(dev_attr->attr.name, "monitor_id")) {
		ret = sprintf(buf, "%d\n", device_info->monitor_id);
	} else if (!strcmp(dev_attr->attr.name, "server_monitor_pending")) {
		ret = sprintf(buf, "%d\n", device_info->server_monitor_pending);
	} else if (!strcmp(dev_attr->attr.name, "server_monitor_latency")) {
		ret = sprintf(buf, "%d\n", device_info->server_monitor_latency);
	} else if (!strcmp(dev_attr->attr.name, "server_monitor_conn_id")) {
		ret = sprintf(buf, "%d\n",
			       device_info->server_monitor_conn_id);
	} else if (!strcmp(dev_attr->attr.name, "client_monitor_pending")) {
		ret = sprintf(buf, "%d\n", device_info->client_monitor_pending);
	} else if (!strcmp(dev_attr->attr.name, "client_monitor_latency")) {
		ret = sprintf(buf, "%d\n", device_info->client_monitor_latency);
	} else if (!strcmp(dev_attr->attr.name, "client_monitor_conn_id")) {
		ret = sprintf(buf, "%d\n",
			       device_info->client_monitor_conn_id);
	}

	kfree(device_info);
	return ret;
}

/* Set up per device attributes in /sys/bus/vmbus/devices/<bus device> */
static struct device_attribute vmbus_device_attrs[] = {
	__ATTR(id, S_IRUGO, vmbus_show_device_attr, NULL),
	__ATTR(state, S_IRUGO, vmbus_show_device_attr, NULL),
	__ATTR(class_id, S_IRUGO, vmbus_show_device_attr, NULL),
	__ATTR(device_id, S_IRUGO, vmbus_show_device_attr, NULL),
	__ATTR(monitor_id, S_IRUGO, vmbus_show_device_attr, NULL),
	__ATTR(modalias, S_IRUGO, vmbus_show_device_attr, NULL),

	__ATTR(server_monitor_pending, S_IRUGO, vmbus_show_device_attr, NULL),
	__ATTR(server_monitor_latency, S_IRUGO, vmbus_show_device_attr, NULL),
	__ATTR(server_monitor_conn_id, S_IRUGO, vmbus_show_device_attr, NULL),

	__ATTR(client_monitor_pending, S_IRUGO, vmbus_show_device_attr, NULL),
	__ATTR(client_monitor_latency, S_IRUGO, vmbus_show_device_attr, NULL),
	__ATTR(client_monitor_conn_id, S_IRUGO, vmbus_show_device_attr, NULL),

	__ATTR(out_intr_mask, S_IRUGO, vmbus_show_device_attr, NULL),
	__ATTR(out_read_index, S_IRUGO, vmbus_show_device_attr, NULL),
	__ATTR(out_write_index, S_IRUGO, vmbus_show_device_attr, NULL),
	__ATTR(out_read_bytes_avail, S_IRUGO, vmbus_show_device_attr, NULL),
	__ATTR(out_write_bytes_avail, S_IRUGO, vmbus_show_device_attr, NULL),

	__ATTR(in_intr_mask, S_IRUGO, vmbus_show_device_attr, NULL),
	__ATTR(in_read_index, S_IRUGO, vmbus_show_device_attr, NULL),
	__ATTR(in_write_index, S_IRUGO, vmbus_show_device_attr, NULL),
	__ATTR(in_read_bytes_avail, S_IRUGO, vmbus_show_device_attr, NULL),
	__ATTR(in_write_bytes_avail, S_IRUGO, vmbus_show_device_attr, NULL),
	__ATTR_NULL
};


/*
 * vmbus_uevent - add uevent for our device
 *
 * This routine is invoked when a device is added or removed on the vmbus to
 * generate a uevent to udev in the userspace. The udev will then look at its
 * rule and the uevent generated here to load the appropriate driver
 *
 * The alias string will be of the form vmbus:guid where guid is the string
 * representation of the device guid (each byte of the guid will be
 * represented with two hex characters.
 */
static int vmbus_uevent(struct device *device, struct kobj_uevent_env *env)
{
	struct hv_device *dev = device_to_hv_device(device);
	int ret;
	char alias_name[VMBUS_ALIAS_LEN + 1];

	print_alias_name(dev, alias_name);
	ret = add_uevent_var(env, "MODALIAS=vmbus:%s", alias_name);
	return ret;
}

static uuid_le null_guid;

static inline bool is_null_guid(const __u8 *guid)
{
	if (memcmp(guid, &null_guid, sizeof(uuid_le)))
		return false;
	return true;
}

/*
 * Return a matching hv_vmbus_device_id pointer.
 * If there is no match, return NULL.
 */
static const struct hv_vmbus_device_id *hv_vmbus_get_id(
					const struct hv_vmbus_device_id *id,
					__u8 *guid)
{
	for (; !is_null_guid(id->guid); id++)
		if (!memcmp(&id->guid, guid, sizeof(uuid_le)))
			return id;

	return NULL;
}



/*
 * vmbus_match - Attempt to match the specified device to the specified driver
 */
static int vmbus_match(struct device *device, struct device_driver *driver)
{
	struct hv_driver *drv = drv_to_hv_drv(driver);
	struct hv_device *hv_dev = device_to_hv_device(device);

	if (hv_vmbus_get_id(drv->id_table, hv_dev->dev_type.b))
		return 1;

	return 0;
}

/*
 * vmbus_probe - Add the new vmbus's child device
 */
static int vmbus_probe(struct device *child_device)
{
	int ret = 0;
	struct hv_driver *drv =
			drv_to_hv_drv(child_device->driver);
	struct hv_device *dev = device_to_hv_device(child_device);
	const struct hv_vmbus_device_id *dev_id;

	dev_id = hv_vmbus_get_id(drv->id_table, dev->dev_type.b);
	if (drv->probe) {
		ret = drv->probe(dev, dev_id);
		if (ret != 0)
			pr_err("probe failed for device %s (%d)\n",
			       dev_name(child_device), ret);

	} else {
		pr_err("probe not set for driver %s\n",
		       dev_name(child_device));
		ret = -ENODEV;
	}
	return ret;
}

/*
 * vmbus_remove - Remove a vmbus device
 */
static int vmbus_remove(struct device *child_device)
{
	struct hv_driver *drv = drv_to_hv_drv(child_device->driver);
	struct hv_device *dev = device_to_hv_device(child_device);

	if (drv->remove)
		drv->remove(dev);
	else
		pr_err("remove not set for driver %s\n",
			dev_name(child_device));

	return 0;
}


/*
 * vmbus_shutdown - Shutdown a vmbus device
 */
static void vmbus_shutdown(struct device *child_device)
{
	struct hv_driver *drv;
	struct hv_device *dev = device_to_hv_device(child_device);


	/* The device may not be attached yet */
	if (!child_device->driver)
		return;

	drv = drv_to_hv_drv(child_device->driver);

	if (drv->shutdown)
		drv->shutdown(dev);

	return;
}


/*
 * vmbus_device_release - Final callback release of the vmbus child device
 */
static void vmbus_device_release(struct device *device)
{
	struct hv_device *hv_dev = device_to_hv_device(device);

	kfree(hv_dev);

}

/* The one and only one */
static struct bus_type  hv_bus = {
	.name =		"vmbus",
	.match =		vmbus_match,
	.shutdown =		vmbus_shutdown,
	.remove =		vmbus_remove,
	.probe =		vmbus_probe,
	.uevent =		vmbus_uevent,
	.dev_attrs =	vmbus_device_attrs,
};

static const char *driver_name = "hyperv";


struct onmessage_work_context {
	struct work_struct work;
	struct hv_message msg;
};

static void vmbus_onmessage_work(struct work_struct *work)
{
	struct onmessage_work_context *ctx;

	ctx = container_of(work, struct onmessage_work_context,
			   work);
	vmbus_onmessage(&ctx->msg);
	kfree(ctx);
}

static void vmbus_on_msg_dpc(unsigned long data)
{
	int cpu = smp_processor_id();
	void *page_addr = hv_context.synic_message_page[cpu];
	struct hv_message *msg = (struct hv_message *)page_addr +
				  VMBUS_MESSAGE_SINT;
	struct onmessage_work_context *ctx;

	while (1) {
		if (msg->header.message_type == HVMSG_NONE) {
			/* no msg */
			break;
		} else {
			ctx = kmalloc(sizeof(*ctx), GFP_ATOMIC);
			if (ctx == NULL)
				continue;
			INIT_WORK(&ctx->work, vmbus_onmessage_work);
			memcpy(&ctx->msg, msg, sizeof(*msg));
			queue_work(vmbus_connection.work_queue, &ctx->work);
		}

		msg->header.message_type = HVMSG_NONE;

		/*
		 * Make sure the write to MessageType (ie set to
		 * HVMSG_NONE) happens before we read the
		 * MessagePending and EOMing. Otherwise, the EOMing
		 * will not deliver any more messages since there is
		 * no empty slot
		 */
		smp_mb();

		if (msg->header.message_flags.msg_pending) {
			/*
			 * This will cause message queue rescan to
			 * possibly deliver another msg from the
			 * hypervisor
			 */
			wrmsrl(HV_X64_MSR_EOM, 0);
		}
	}
}

static irqreturn_t vmbus_isr(int irq, void *dev_id)
{
	int cpu = smp_processor_id();
	void *page_addr;
	struct hv_message *msg;
	union hv_synic_event_flags *event;
	bool handled = false;

	/*
	 * Check for events before checking for messages. This is the order
	 * in which events and messages are checked in Windows guests on
	 * Hyper-V, and the Windows team suggested we do the same.
	 */

	page_addr = hv_context.synic_event_page[cpu];
	event = (union hv_synic_event_flags *)page_addr + VMBUS_MESSAGE_SINT;

	/* Since we are a child, we only need to check bit 0 */
	if (sync_test_and_clear_bit(0, (unsigned long *) &event->flags32[0])) {
		handled = true;
		tasklet_schedule(&event_dpc);
	}

	page_addr = hv_context.synic_message_page[cpu];
	msg = (struct hv_message *)page_addr + VMBUS_MESSAGE_SINT;

	/* Check if there are actual msgs to be processed */
	if (msg->header.message_type != HVMSG_NONE) {
		handled = true;
		tasklet_schedule(&msg_dpc);
	}

	if (handled)
		return IRQ_HANDLED;
	else
		return IRQ_NONE;
}

/*
 * vmbus_bus_init -Main vmbus driver initialization routine.
 *
 * Here, we
 *	- initialize the vmbus driver context
 *	- invoke the vmbus hv main init routine
 *	- get the irq resource
 *	- retrieve the channel offers
 */
static int vmbus_bus_init(int irq)
{
	int ret;
	unsigned int vector;

	/* Hypervisor initialization...setup hypercall page..etc */
	ret = hv_init();
	if (ret != 0) {
		pr_err("Unable to initialize the hypervisor - 0x%x\n", ret);
		return ret;
	}

	tasklet_init(&msg_dpc, vmbus_on_msg_dpc, 0);
	tasklet_init(&event_dpc, vmbus_on_event, 0);

	ret = bus_register(&hv_bus);
	if (ret)
		goto err_cleanup;

	ret = request_irq(irq, vmbus_isr, 0, driver_name, hv_acpi_dev);

	if (ret != 0) {
		pr_err("Unable to request IRQ %d\n",
			   irq);
		goto err_unregister;
	}

	vector = IRQ0_VECTOR + irq;

	/*
	 * Notify the hypervisor of our irq and
	 * connect to the host.
	 */
	on_each_cpu(hv_synic_init, (void *)&vector, 1);
	ret = vmbus_connect();
	if (ret)
		goto err_irq;

	vmbus_request_offers();

	return 0;

err_irq:
	free_irq(irq, hv_acpi_dev);

err_unregister:
	bus_unregister(&hv_bus);

err_cleanup:
	hv_cleanup();

	return ret;
}

/**
 * __vmbus_child_driver_register - Register a vmbus's driver
 * @drv: Pointer to driver structure you want to register
 * @owner: owner module of the drv
 * @mod_name: module name string
 *
 * Registers the given driver with Linux through the 'driver_register()' call
 * and sets up the hyper-v vmbus handling for this driver.
 * It will return the state of the 'driver_register()' call.
 *
 */
int __vmbus_driver_register(struct hv_driver *hv_driver, struct module *owner, const char *mod_name)
{
	int ret;

	pr_info("registering driver %s\n", hv_driver->name);

	ret = vmbus_exists();
	if (ret < 0)
		return ret;

	hv_driver->driver.name = hv_driver->name;
	hv_driver->driver.owner = owner;
	hv_driver->driver.mod_name = mod_name;
	hv_driver->driver.bus = &hv_bus;

	ret = driver_register(&hv_driver->driver);

	vmbus_request_offers();

	return ret;
}
EXPORT_SYMBOL_GPL(__vmbus_driver_register);

/**
 * vmbus_driver_unregister() - Unregister a vmbus's driver
 * @drv: Pointer to driver structure you want to un-register
 *
 * Un-register the given driver that was previous registered with a call to
 * vmbus_driver_register()
 */
void vmbus_driver_unregister(struct hv_driver *hv_driver)
{
	pr_info("unregistering driver %s\n", hv_driver->name);

	if (!vmbus_exists())
		driver_unregister(&hv_driver->driver);
}
EXPORT_SYMBOL_GPL(vmbus_driver_unregister);

/*
 * vmbus_device_create - Creates and registers a new child device
 * on the vmbus.
 */
struct hv_device *vmbus_device_create(uuid_le *type,
					    uuid_le *instance,
					    struct vmbus_channel *channel)
{
	struct hv_device *child_device_obj;

	child_device_obj = kzalloc(sizeof(struct hv_device), GFP_KERNEL);
	if (!child_device_obj) {
		pr_err("Unable to allocate device object for child device\n");
		return NULL;
	}

	child_device_obj->channel = channel;
	memcpy(&child_device_obj->dev_type, type, sizeof(uuid_le));
	memcpy(&child_device_obj->dev_instance, instance,
	       sizeof(uuid_le));


	return child_device_obj;
}

/*
 * vmbus_device_register - Register the child device
 */
int vmbus_device_register(struct hv_device *child_device_obj)
{
	int ret = 0;

	static atomic_t device_num = ATOMIC_INIT(0);

	dev_set_name(&child_device_obj->device, "vmbus_0_%d",
		     atomic_inc_return(&device_num));

	child_device_obj->device.bus = &hv_bus;
	child_device_obj->device.parent = &hv_acpi_dev->dev;
	child_device_obj->device.release = vmbus_device_release;

	/*
	 * Register with the LDM. This will kick off the driver/device
	 * binding...which will eventually call vmbus_match() and vmbus_probe()
	 */
	ret = device_register(&child_device_obj->device);

	if (ret)
		pr_err("Unable to register child device\n");
	else
		pr_info("child device %s registered\n",
			dev_name(&child_device_obj->device));

	return ret;
}

/*
 * vmbus_device_unregister - Remove the specified child device
 * from the vmbus.
 */
void vmbus_device_unregister(struct hv_device *device_obj)
{
	/*
	 * Kick off the process of unregistering the device.
	 * This will call vmbus_remove() and eventually vmbus_device_release()
	 */
	device_unregister(&device_obj->device);

	pr_info("child device %s unregistered\n",
		dev_name(&device_obj->device));
}


/*
 * VMBUS is an acpi enumerated device. Get the the IRQ information
 * from DSDT.
 */

static acpi_status vmbus_walk_resources(struct acpi_resource *res, void *irq)
{

	if (res->type == ACPI_RESOURCE_TYPE_IRQ) {
		struct acpi_resource_irq *irqp;
		irqp = &res->data.irq;

		*((unsigned int *)irq) = irqp->interrupts[0];
	}

	return AE_OK;
}

static int vmbus_acpi_add(struct acpi_device *device)
{
	acpi_status result;

	hv_acpi_dev = device;

	result = acpi_walk_resources(device->handle, METHOD_NAME__CRS,
					vmbus_walk_resources, &irq);

	if (ACPI_FAILURE(result)) {
		complete(&probe_event);
		return -ENODEV;
	}
	complete(&probe_event);
	return 0;
}

static const struct acpi_device_id vmbus_acpi_device_ids[] = {
	{"VMBUS", 0},
	{"VMBus", 0},
	{"", 0},
};
MODULE_DEVICE_TABLE(acpi, vmbus_acpi_device_ids);

static struct acpi_driver vmbus_acpi_driver = {
	.name = "vmbus",
	.ids = vmbus_acpi_device_ids,
	.ops = {
		.add = vmbus_acpi_add,
	},
};

/*
 * query_hypervisor_presence
 * - Query the cpuid for presence of windows hypervisor
 */
static int query_hypervisor_presence(void)
{
	unsigned int eax;
	unsigned int ebx;
	unsigned int ecx;
	unsigned int edx;
	unsigned int op;

	eax = 0;
	ebx = 0;
	ecx = 0;
	edx = 0;
	op = HVCPUID_VERSION_FEATURES;
	cpuid(op, &eax, &ebx, &ecx, &edx);

	return ecx & HV_PRESENT_BIT;
}

static int __init hv_acpi_init(void)
{
	int ret, t;

	if (!query_hypervisor_presence())
		return -ENODEV;

	init_completion(&probe_event);

	/*
	 * Get irq resources first.
	 */

	ret = acpi_bus_register_driver(&vmbus_acpi_driver);

	if (ret)
		return ret;

	t = wait_for_completion_timeout(&probe_event, 5*HZ);
	if (t == 0) {
		ret = -ETIMEDOUT;
		goto cleanup;
	}

	if (irq <= 0) {
		ret = -ENODEV;
		goto cleanup;
	}

	ret = vmbus_bus_init(irq);
	if (ret)
		goto cleanup;

	return 0;

cleanup:
	acpi_bus_unregister_driver(&vmbus_acpi_driver);
	hv_acpi_dev = NULL;
	return ret;
}

static void __exit vmbus_exit(void)
{

	free_irq(irq, hv_acpi_dev);
	vmbus_free_channels();
	bus_unregister(&hv_bus);
	hv_cleanup();
	acpi_bus_unregister_driver(&vmbus_acpi_driver);
}


MODULE_LICENSE("GPL");
MODULE_VERSION(HV_DRV_VERSION);

subsys_initcall(hv_acpi_init);
module_exit(vmbus_exit);