summaryrefslogtreecommitdiffstats
path: root/drivers/misc/mic/vop/vop_main.c
blob: a341938c7e2c6738027dd4df53cdf4da0f8b6bd1 (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
/*
 * Intel MIC Platform Software Stack (MPSS)
 *
 * Copyright(c) 2016 Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License, version 2, 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.
 *
 * The full GNU General Public License is included in this distribution in
 * the file called "COPYING".
 *
 * Adapted from:
 *
 * virtio for kvm on s390
 *
 * Copyright IBM Corp. 2008
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License (version 2 only)
 * as published by the Free Software Foundation.
 *
 *    Author(s): Christian Borntraeger <borntraeger@de.ibm.com>
 *
 * Intel Virtio Over PCIe (VOP) driver.
 *
 */
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/dma-mapping.h>

#include "vop_main.h"

#define VOP_MAX_VRINGS 4

/*
 * _vop_vdev - Allocated per virtio device instance injected by the peer.
 *
 * @vdev: Virtio device
 * @desc: Virtio device page descriptor
 * @dc: Virtio device control
 * @vpdev: VOP device which is the parent for this virtio device
 * @vr: Buffer for accessing the VRING
 * @used: Buffer for used
 * @used_size: Size of the used buffer
 * @reset_done: Track whether VOP reset is complete
 * @virtio_cookie: Cookie returned upon requesting a interrupt
 * @c2h_vdev_db: The doorbell used by the guest to interrupt the host
 * @h2c_vdev_db: The doorbell used by the host to interrupt the guest
 * @dnode: The destination node
 */
struct _vop_vdev {
	struct virtio_device vdev;
	struct mic_device_desc __iomem *desc;
	struct mic_device_ctrl __iomem *dc;
	struct vop_device *vpdev;
	void __iomem *vr[VOP_MAX_VRINGS];
	dma_addr_t used[VOP_MAX_VRINGS];
	int used_size[VOP_MAX_VRINGS];
	struct completion reset_done;
	struct mic_irq *virtio_cookie;
	int c2h_vdev_db;
	int h2c_vdev_db;
	int dnode;
};

#define to_vopvdev(vd) container_of(vd, struct _vop_vdev, vdev)

#define _vop_aligned_desc_size(d) __mic_align(_vop_desc_size(d), 8)

/* Helper API to obtain the parent of the virtio device */
static inline struct device *_vop_dev(struct _vop_vdev *vdev)
{
	return vdev->vdev.dev.parent;
}

static inline unsigned _vop_desc_size(struct mic_device_desc __iomem *desc)
{
	return sizeof(*desc)
		+ ioread8(&desc->num_vq) * sizeof(struct mic_vqconfig)
		+ ioread8(&desc->feature_len) * 2
		+ ioread8(&desc->config_len);
}

static inline struct mic_vqconfig __iomem *
_vop_vq_config(struct mic_device_desc __iomem *desc)
{
	return (struct mic_vqconfig __iomem *)(desc + 1);
}

static inline u8 __iomem *
_vop_vq_features(struct mic_device_desc __iomem *desc)
{
	return (u8 __iomem *)(_vop_vq_config(desc) + ioread8(&desc->num_vq));
}

static inline u8 __iomem *
_vop_vq_configspace(struct mic_device_desc __iomem *desc)
{
	return _vop_vq_features(desc) + ioread8(&desc->feature_len) * 2;
}

static inline unsigned
_vop_total_desc_size(struct mic_device_desc __iomem *desc)
{
	return _vop_aligned_desc_size(desc) + sizeof(struct mic_device_ctrl);
}

/* This gets the device's feature bits. */
static u64 vop_get_features(struct virtio_device *vdev)
{
	unsigned int i, bits;
	u32 features = 0;
	struct mic_device_desc __iomem *desc = to_vopvdev(vdev)->desc;
	u8 __iomem *in_features = _vop_vq_features(desc);
	int feature_len = ioread8(&desc->feature_len);

	bits = min_t(unsigned, feature_len, sizeof(vdev->features)) * 8;
	for (i = 0; i < bits; i++)
		if (ioread8(&in_features[i / 8]) & (BIT(i % 8)))
			features |= BIT(i);

	return features;
}

static int vop_finalize_features(struct virtio_device *vdev)
{
	unsigned int i, bits;
	struct mic_device_desc __iomem *desc = to_vopvdev(vdev)->desc;
	u8 feature_len = ioread8(&desc->feature_len);
	/* Second half of bitmap is features we accept. */
	u8 __iomem *out_features =
		_vop_vq_features(desc) + feature_len;

	/* Give virtio_ring a chance to accept features. */
	vring_transport_features(vdev);

	memset_io(out_features, 0, feature_len);
	bits = min_t(unsigned, feature_len,
		     sizeof(vdev->features)) * 8;
	for (i = 0; i < bits; i++) {
		if (__virtio_test_bit(vdev, i))
			iowrite8(ioread8(&out_features[i / 8]) | (1 << (i % 8)),
				 &out_features[i / 8]);
	}
	return 0;
}

/*
 * Reading and writing elements in config space
 */
static void vop_get(struct virtio_device *vdev, unsigned int offset,
		    void *buf, unsigned len)
{
	struct mic_device_desc __iomem *desc = to_vopvdev(vdev)->desc;

	if (offset + len > ioread8(&desc->config_len))
		return;
	memcpy_fromio(buf, _vop_vq_configspace(desc) + offset, len);
}

static void vop_set(struct virtio_device *vdev, unsigned int offset,
		    const void *buf, unsigned len)
{
	struct mic_device_desc __iomem *desc = to_vopvdev(vdev)->desc;

	if (offset + len > ioread8(&desc->config_len))
		return;
	memcpy_toio(_vop_vq_configspace(desc) + offset, buf, len);
}

/*
 * The operations to get and set the status word just access the status
 * field of the device descriptor. set_status also interrupts the host
 * to tell about status changes.
 */
static u8 vop_get_status(struct virtio_device *vdev)
{
	return ioread8(&to_vopvdev(vdev)->desc->status);
}

static void vop_set_status(struct virtio_device *dev, u8 status)
{
	struct _vop_vdev *vdev = to_vopvdev(dev);
	struct vop_device *vpdev = vdev->vpdev;

	if (!status)
		return;
	iowrite8(status, &vdev->desc->status);
	vpdev->hw_ops->send_intr(vpdev, vdev->c2h_vdev_db);
}

/* Inform host on a virtio device reset and wait for ack from host */
static void vop_reset_inform_host(struct virtio_device *dev)
{
	struct _vop_vdev *vdev = to_vopvdev(dev);
	struct mic_device_ctrl __iomem *dc = vdev->dc;
	struct vop_device *vpdev = vdev->vpdev;
	int retry;

	iowrite8(0, &dc->host_ack);
	iowrite8(1, &dc->vdev_reset);
	vpdev->hw_ops->send_intr(vpdev, vdev->c2h_vdev_db);

	/* Wait till host completes all card accesses and acks the reset */
	for (retry = 100; retry--;) {
		if (ioread8(&dc->host_ack))
			break;
		msleep(100);
	};

	dev_dbg(_vop_dev(vdev), "%s: retry: %d\n", __func__, retry);

	/* Reset status to 0 in case we timed out */
	iowrite8(0, &vdev->desc->status);
}

static void vop_reset(struct virtio_device *dev)
{
	struct _vop_vdev *vdev = to_vopvdev(dev);

	dev_dbg(_vop_dev(vdev), "%s: virtio id %d\n",
		__func__, dev->id.device);

	vop_reset_inform_host(dev);
	complete_all(&vdev->reset_done);
}

/*
 * The virtio_ring code calls this API when it wants to notify the Host.
 */
static bool vop_notify(struct virtqueue *vq)
{
	struct _vop_vdev *vdev = vq->priv;
	struct vop_device *vpdev = vdev->vpdev;

	vpdev->hw_ops->send_intr(vpdev, vdev->c2h_vdev_db);
	return true;
}

static void vop_del_vq(struct virtqueue *vq, int n)
{
	struct _vop_vdev *vdev = to_vopvdev(vq->vdev);
	struct vring *vr = (struct vring *)(vq + 1);
	struct vop_device *vpdev = vdev->vpdev;

	dma_unmap_single(&vpdev->dev, vdev->used[n],
			 vdev->used_size[n], DMA_BIDIRECTIONAL);
	free_pages((unsigned long)vr->used, get_order(vdev->used_size[n]));
	vring_del_virtqueue(vq);
	vpdev->hw_ops->iounmap(vpdev, vdev->vr[n]);
	vdev->vr[n] = NULL;
}

static void vop_del_vqs(struct virtio_device *dev)
{
	struct _vop_vdev *vdev = to_vopvdev(dev);
	struct virtqueue *vq, *n;
	int idx = 0;

	dev_dbg(_vop_dev(vdev), "%s\n", __func__);

	list_for_each_entry_safe(vq, n, &dev->vqs, list)
		vop_del_vq(vq, idx++);
}

/*
 * This routine will assign vring's allocated in host/io memory. Code in
 * virtio_ring.c however continues to access this io memory as if it were local
 * memory without io accessors.
 */
static struct virtqueue *vop_find_vq(struct virtio_device *dev,
				     unsigned index,
				     void (*callback)(struct virtqueue *vq),
				     const char *name, bool ctx)
{
	struct _vop_vdev *vdev = to_vopvdev(dev);
	struct vop_device *vpdev = vdev->vpdev;
	struct mic_vqconfig __iomem *vqconfig;
	struct mic_vqconfig config;
	struct virtqueue *vq;
	void __iomem *va;
	struct _mic_vring_info __iomem *info;
	void *used;
	int vr_size, _vr_size, err, magic;
	struct vring *vr;
	u8 type = ioread8(&vdev->desc->type);

	if (index >= ioread8(&vdev->desc->num_vq))
		return ERR_PTR(-ENOENT);

	if (!name)
		return ERR_PTR(-ENOENT);

	/* First assign the vring's allocated in host memory */
	vqconfig = _vop_vq_config(vdev->desc) + index;
	memcpy_fromio(&config, vqconfig, sizeof(config));
	_vr_size = vring_size(le16_to_cpu(config.num), MIC_VIRTIO_RING_ALIGN);
	vr_size = PAGE_ALIGN(_vr_size + sizeof(struct _mic_vring_info));
	va = vpdev->hw_ops->ioremap(vpdev, le64_to_cpu(config.address),
			vr_size);
	if (!va)
		return ERR_PTR(-ENOMEM);
	vdev->vr[index] = va;
	memset_io(va, 0x0, _vr_size);
	vq = vring_new_virtqueue(
				index,
				le16_to_cpu(config.num), MIC_VIRTIO_RING_ALIGN,
				dev,
				false,
				ctx,
				(void __force *)va, vop_notify, callback, name);
	if (!vq) {
		err = -ENOMEM;
		goto unmap;
	}
	info = va + _vr_size;
	magic = ioread32(&info->magic);

	if (WARN(magic != MIC_MAGIC + type + index, "magic mismatch")) {
		err = -EIO;
		goto unmap;
	}

	/* Allocate and reassign used ring now */
	vdev->used_size[index] = PAGE_ALIGN(sizeof(__u16) * 3 +
					     sizeof(struct vring_used_elem) *
					     le16_to_cpu(config.num));
	used = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
					get_order(vdev->used_size[index]));
	if (!used) {
		err = -ENOMEM;
		dev_err(_vop_dev(vdev), "%s %d err %d\n",
			__func__, __LINE__, err);
		goto del_vq;
	}
	vdev->used[index] = dma_map_single(&vpdev->dev, used,
					    vdev->used_size[index],
					    DMA_BIDIRECTIONAL);
	if (dma_mapping_error(&vpdev->dev, vdev->used[index])) {
		err = -ENOMEM;
		dev_err(_vop_dev(vdev), "%s %d err %d\n",
			__func__, __LINE__, err);
		goto free_used;
	}
	writeq(vdev->used[index], &vqconfig->used_address);
	/*
	 * To reassign the used ring here we are directly accessing
	 * struct vring_virtqueue which is a private data structure
	 * in virtio_ring.c. At the minimum, a BUILD_BUG_ON() in
	 * vring_new_virtqueue() would ensure that
	 *  (&vq->vring == (struct vring *) (&vq->vq + 1));
	 */
	vr = (struct vring *)(vq + 1);
	vr->used = used;

	vq->priv = vdev;
	return vq;
free_used:
	free_pages((unsigned long)used,
		   get_order(vdev->used_size[index]));
del_vq:
	vring_del_virtqueue(vq);
unmap:
	vpdev->hw_ops->iounmap(vpdev, vdev->vr[index]);
	return ERR_PTR(err);
}

static int vop_find_vqs(struct virtio_device *dev, unsigned nvqs,
			struct virtqueue *vqs[],
			vq_callback_t *callbacks[],
			const char * const names[], const bool *ctx,
			struct irq_affinity *desc)
{
	struct _vop_vdev *vdev = to_vopvdev(dev);
	struct vop_device *vpdev = vdev->vpdev;
	struct mic_device_ctrl __iomem *dc = vdev->dc;
	int i, err, retry;

	/* We must have this many virtqueues. */
	if (nvqs > ioread8(&vdev->desc->num_vq))
		return -ENOENT;

	for (i = 0; i < nvqs; ++i) {
		dev_dbg(_vop_dev(vdev), "%s: %d: %s\n",
			__func__, i, names[i]);
		vqs[i] = vop_find_vq(dev, i, callbacks[i], names[i],
				     ctx ? ctx[i] : false);
		if (IS_ERR(vqs[i])) {
			err = PTR_ERR(vqs[i]);
			goto error;
		}
	}

	iowrite8(1, &dc->used_address_updated);
	/*
	 * Send an interrupt to the host to inform it that used
	 * rings have been re-assigned.
	 */
	vpdev->hw_ops->send_intr(vpdev, vdev->c2h_vdev_db);
	for (retry = 100; --retry;) {
		if (!ioread8(&dc->used_address_updated))
			break;
		msleep(100);
	};

	dev_dbg(_vop_dev(vdev), "%s: retry: %d\n", __func__, retry);
	if (!retry) {
		err = -ENODEV;
		goto error;
	}

	return 0;
error:
	vop_del_vqs(dev);
	return err;
}

/*
 * The config ops structure as defined by virtio config
 */
static struct virtio_config_ops vop_vq_config_ops = {
	.get_features = vop_get_features,
	.finalize_features = vop_finalize_features,
	.get = vop_get,
	.set = vop_set,
	.get_status = vop_get_status,
	.set_status = vop_set_status,
	.reset = vop_reset,
	.find_vqs = vop_find_vqs,
	.del_vqs = vop_del_vqs,
};

static irqreturn_t vop_virtio_intr_handler(int irq, void *data)
{
	struct _vop_vdev *vdev = data;
	struct vop_device *vpdev = vdev->vpdev;
	struct virtqueue *vq;

	vpdev->hw_ops->ack_interrupt(vpdev, vdev->h2c_vdev_db);
	list_for_each_entry(vq, &vdev->vdev.vqs, list)
		vring_interrupt(0, vq);

	return IRQ_HANDLED;
}

static void vop_virtio_release_dev(struct device *_d)
{
	/*
	 * No need for a release method similar to virtio PCI.
	 * Provide an empty one to avoid getting a warning from core.
	 */
}

/*
 * adds a new device and register it with virtio
 * appropriate drivers are loaded by the device model
 */
static int _vop_add_device(struct mic_device_desc __iomem *d,
			   unsigned int offset, struct vop_device *vpdev,
			   int dnode)
{
	struct _vop_vdev *vdev;
	int ret;
	u8 type = ioread8(&d->type);

	vdev = kzalloc(sizeof(*vdev), GFP_KERNEL);
	if (!vdev)
		return -ENOMEM;

	vdev->vpdev = vpdev;
	vdev->vdev.dev.parent = &vpdev->dev;
	vdev->vdev.dev.release = vop_virtio_release_dev;
	vdev->vdev.id.device = type;
	vdev->vdev.config = &vop_vq_config_ops;
	vdev->desc = d;
	vdev->dc = (void __iomem *)d + _vop_aligned_desc_size(d);
	vdev->dnode = dnode;
	vdev->vdev.priv = (void *)(u64)dnode;
	init_completion(&vdev->reset_done);

	vdev->h2c_vdev_db = vpdev->hw_ops->next_db(vpdev);
	vdev->virtio_cookie = vpdev->hw_ops->request_irq(vpdev,
			vop_virtio_intr_handler, "virtio intr",
			vdev, vdev->h2c_vdev_db);
	if (IS_ERR(vdev->virtio_cookie)) {
		ret = PTR_ERR(vdev->virtio_cookie);
		goto kfree;
	}
	iowrite8((u8)vdev->h2c_vdev_db, &vdev->dc->h2c_vdev_db);
	vdev->c2h_vdev_db = ioread8(&vdev->dc->c2h_vdev_db);

	ret = register_virtio_device(&vdev->vdev);
	if (ret) {
		dev_err(_vop_dev(vdev),
			"Failed to register vop device %u type %u\n",
			offset, type);
		goto free_irq;
	}
	writeq((u64)vdev, &vdev->dc->vdev);
	dev_dbg(_vop_dev(vdev), "%s: registered vop device %u type %u vdev %p\n",
		__func__, offset, type, vdev);

	return 0;

free_irq:
	vpdev->hw_ops->free_irq(vpdev, vdev->virtio_cookie, vdev);
kfree:
	kfree(vdev);
	return ret;
}

/*
 * match for a vop device with a specific desc pointer
 */
static int vop_match_desc(struct device *dev, void *data)
{
	struct virtio_device *_dev = dev_to_virtio(dev);
	struct _vop_vdev *vdev = to_vopvdev(_dev);

	return vdev->desc == (void __iomem *)data;
}

static void _vop_handle_config_change(struct mic_device_desc __iomem *d,
				      unsigned int offset,
				      struct vop_device *vpdev)
{
	struct mic_device_ctrl __iomem *dc
		= (void __iomem *)d + _vop_aligned_desc_size(d);
	struct _vop_vdev *vdev = (struct _vop_vdev *)readq(&dc->vdev);

	if (ioread8(&dc->config_change) != MIC_VIRTIO_PARAM_CONFIG_CHANGED)
		return;

	dev_dbg(&vpdev->dev, "%s %d\n", __func__, __LINE__);
	virtio_config_changed(&vdev->vdev);
	iowrite8(1, &dc->guest_ack);
}

/*
 * removes a virtio device if a hot remove event has been
 * requested by the host.
 */
static int _vop_remove_device(struct mic_device_desc __iomem *d,
			      unsigned int offset, struct vop_device *vpdev)
{
	struct mic_device_ctrl __iomem *dc
		= (void __iomem *)d + _vop_aligned_desc_size(d);
	struct _vop_vdev *vdev = (struct _vop_vdev *)readq(&dc->vdev);
	u8 status;
	int ret = -1;

	if (ioread8(&dc->config_change) == MIC_VIRTIO_PARAM_DEV_REMOVE) {
		dev_dbg(&vpdev->dev,
			"%s %d config_change %d type %d vdev %p\n",
			__func__, __LINE__,
			ioread8(&dc->config_change), ioread8(&d->type), vdev);
		status = ioread8(&d->status);
		reinit_completion(&vdev->reset_done);
		unregister_virtio_device(&vdev->vdev);
		vpdev->hw_ops->free_irq(vpdev, vdev->virtio_cookie, vdev);
		iowrite8(-1, &dc->h2c_vdev_db);
		if (status & VIRTIO_CONFIG_S_DRIVER_OK)
			wait_for_completion(&vdev->reset_done);
		kfree(vdev);
		iowrite8(1, &dc->guest_ack);
		dev_dbg(&vpdev->dev, "%s %d guest_ack %d\n",
			__func__, __LINE__, ioread8(&dc->guest_ack));
		iowrite8(-1, &d->type);
		ret = 0;
	}
	return ret;
}

#define REMOVE_DEVICES true

static void _vop_scan_devices(void __iomem *dp, struct vop_device *vpdev,
			      bool remove, int dnode)
{
	s8 type;
	unsigned int i;
	struct mic_device_desc __iomem *d;
	struct mic_device_ctrl __iomem *dc;
	struct device *dev;
	int ret;

	for (i = sizeof(struct mic_bootparam);
			i < MIC_DP_SIZE; i += _vop_total_desc_size(d)) {
		d = dp + i;
		dc = (void __iomem *)d + _vop_aligned_desc_size(d);
		/*
		 * This read barrier is paired with the corresponding write
		 * barrier on the host which is inserted before adding or
		 * removing a virtio device descriptor, by updating the type.
		 */
		rmb();
		type = ioread8(&d->type);

		/* end of list */
		if (type == 0)
			break;

		if (type == -1)
			continue;

		/* device already exists */
		dev = device_find_child(&vpdev->dev, (void __force *)d,
					vop_match_desc);
		if (dev) {
			if (remove)
				iowrite8(MIC_VIRTIO_PARAM_DEV_REMOVE,
					 &dc->config_change);
			put_device(dev);
			_vop_handle_config_change(d, i, vpdev);
			ret = _vop_remove_device(d, i, vpdev);
			if (remove) {
				iowrite8(0, &dc->config_change);
				iowrite8(0, &dc->guest_ack);
			}
			continue;
		}

		/* new device */
		dev_dbg(&vpdev->dev, "%s %d Adding new virtio device %p\n",
			__func__, __LINE__, d);
		if (!remove)
			_vop_add_device(d, i, vpdev, dnode);
	}
}

static void vop_scan_devices(struct vop_info *vi,
			     struct vop_device *vpdev, bool remove)
{
	void __iomem *dp = vpdev->hw_ops->get_remote_dp(vpdev);

	if (!dp)
		return;
	mutex_lock(&vi->vop_mutex);
	_vop_scan_devices(dp, vpdev, remove, vpdev->dnode);
	mutex_unlock(&vi->vop_mutex);
}

/*
 * vop_hotplug_device tries to find changes in the device page.
 */
static void vop_hotplug_devices(struct work_struct *work)
{
	struct vop_info *vi = container_of(work, struct vop_info,
					     hotplug_work);

	vop_scan_devices(vi, vi->vpdev, !REMOVE_DEVICES);
}

/*
 * Interrupt handler for hot plug/config changes etc.
 */
static irqreturn_t vop_extint_handler(int irq, void *data)
{
	struct vop_info *vi = data;
	struct mic_bootparam __iomem *bp;
	struct vop_device *vpdev = vi->vpdev;

	bp = vpdev->hw_ops->get_remote_dp(vpdev);
	dev_dbg(&vpdev->dev, "%s %d hotplug work\n",
		__func__, __LINE__);
	vpdev->hw_ops->ack_interrupt(vpdev, ioread8(&bp->h2c_config_db));
	schedule_work(&vi->hotplug_work);
	return IRQ_HANDLED;
}

static int vop_driver_probe(struct vop_device *vpdev)
{
	struct vop_info *vi;
	int rc;

	vi = kzalloc(sizeof(*vi), GFP_KERNEL);
	if (!vi) {
		rc = -ENOMEM;
		goto exit;
	}
	dev_set_drvdata(&vpdev->dev, vi);
	vi->vpdev = vpdev;

	mutex_init(&vi->vop_mutex);
	INIT_WORK(&vi->hotplug_work, vop_hotplug_devices);
	if (vpdev->dnode) {
		rc = vop_host_init(vi);
		if (rc < 0)
			goto free;
	} else {
		struct mic_bootparam __iomem *bootparam;

		vop_scan_devices(vi, vpdev, !REMOVE_DEVICES);

		vi->h2c_config_db = vpdev->hw_ops->next_db(vpdev);
		vi->cookie = vpdev->hw_ops->request_irq(vpdev,
							vop_extint_handler,
							"virtio_config_intr",
							vi, vi->h2c_config_db);
		if (IS_ERR(vi->cookie)) {
			rc = PTR_ERR(vi->cookie);
			goto free;
		}
		bootparam = vpdev->hw_ops->get_remote_dp(vpdev);
		iowrite8(vi->h2c_config_db, &bootparam->h2c_config_db);
	}
	vop_init_debugfs(vi);
	return 0;
free:
	kfree(vi);
exit:
	return rc;
}

static void vop_driver_remove(struct vop_device *vpdev)
{
	struct vop_info *vi = dev_get_drvdata(&vpdev->dev);

	if (vpdev->dnode) {
		vop_host_uninit(vi);
	} else {
		struct mic_bootparam __iomem *bootparam =
			vpdev->hw_ops->get_remote_dp(vpdev);
		if (bootparam)
			iowrite8(-1, &bootparam->h2c_config_db);
		vpdev->hw_ops->free_irq(vpdev, vi->cookie, vi);
		flush_work(&vi->hotplug_work);
		vop_scan_devices(vi, vpdev, REMOVE_DEVICES);
	}
	vop_exit_debugfs(vi);
	kfree(vi);
}

static struct vop_device_id id_table[] = {
	{ VOP_DEV_TRNSP, VOP_DEV_ANY_ID },
	{ 0 },
};

static struct vop_driver vop_driver = {
	.driver.name =	KBUILD_MODNAME,
	.driver.owner =	THIS_MODULE,
	.id_table = id_table,
	.probe = vop_driver_probe,
	.remove = vop_driver_remove,
};

module_vop_driver(vop_driver);

MODULE_DEVICE_TABLE(mbus, id_table);
MODULE_AUTHOR("Intel Corporation");
MODULE_DESCRIPTION("Intel(R) Virtio Over PCIe (VOP) driver");
MODULE_LICENSE("GPL v2");