Merge tags 'cris-for-4.16' and 'cris-for-4.16-urgent' of git://git.kernel.org/pub...
[muen/linux.git] / drivers / misc / mic / vop / vop_main.c
1 /*
2  * Intel MIC Platform Software Stack (MPSS)
3  *
4  * Copyright(c) 2016 Intel Corporation.
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License, version 2, as
8  * published by the Free Software Foundation.
9  *
10  * This program is distributed in the hope that it will be useful, but
11  * WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13  * General Public License for more details.
14  *
15  * The full GNU General Public License is included in this distribution in
16  * the file called "COPYING".
17  *
18  * Adapted from:
19  *
20  * virtio for kvm on s390
21  *
22  * Copyright IBM Corp. 2008
23  *
24  * This program is free software; you can redistribute it and/or modify
25  * it under the terms of the GNU General Public License (version 2 only)
26  * as published by the Free Software Foundation.
27  *
28  *    Author(s): Christian Borntraeger <borntraeger@de.ibm.com>
29  *
30  * Intel Virtio Over PCIe (VOP) driver.
31  *
32  */
33 #include <linux/delay.h>
34 #include <linux/module.h>
35 #include <linux/sched.h>
36 #include <linux/dma-mapping.h>
37
38 #include "vop_main.h"
39
40 #define VOP_MAX_VRINGS 4
41
42 /*
43  * _vop_vdev - Allocated per virtio device instance injected by the peer.
44  *
45  * @vdev: Virtio device
46  * @desc: Virtio device page descriptor
47  * @dc: Virtio device control
48  * @vpdev: VOP device which is the parent for this virtio device
49  * @vr: Buffer for accessing the VRING
50  * @used: Buffer for used
51  * @used_size: Size of the used buffer
52  * @reset_done: Track whether VOP reset is complete
53  * @virtio_cookie: Cookie returned upon requesting a interrupt
54  * @c2h_vdev_db: The doorbell used by the guest to interrupt the host
55  * @h2c_vdev_db: The doorbell used by the host to interrupt the guest
56  * @dnode: The destination node
57  */
58 struct _vop_vdev {
59         struct virtio_device vdev;
60         struct mic_device_desc __iomem *desc;
61         struct mic_device_ctrl __iomem *dc;
62         struct vop_device *vpdev;
63         void __iomem *vr[VOP_MAX_VRINGS];
64         dma_addr_t used[VOP_MAX_VRINGS];
65         int used_size[VOP_MAX_VRINGS];
66         struct completion reset_done;
67         struct mic_irq *virtio_cookie;
68         int c2h_vdev_db;
69         int h2c_vdev_db;
70         int dnode;
71 };
72
73 #define to_vopvdev(vd) container_of(vd, struct _vop_vdev, vdev)
74
75 #define _vop_aligned_desc_size(d) __mic_align(_vop_desc_size(d), 8)
76
77 /* Helper API to obtain the parent of the virtio device */
78 static inline struct device *_vop_dev(struct _vop_vdev *vdev)
79 {
80         return vdev->vdev.dev.parent;
81 }
82
83 static inline unsigned _vop_desc_size(struct mic_device_desc __iomem *desc)
84 {
85         return sizeof(*desc)
86                 + ioread8(&desc->num_vq) * sizeof(struct mic_vqconfig)
87                 + ioread8(&desc->feature_len) * 2
88                 + ioread8(&desc->config_len);
89 }
90
91 static inline struct mic_vqconfig __iomem *
92 _vop_vq_config(struct mic_device_desc __iomem *desc)
93 {
94         return (struct mic_vqconfig __iomem *)(desc + 1);
95 }
96
97 static inline u8 __iomem *
98 _vop_vq_features(struct mic_device_desc __iomem *desc)
99 {
100         return (u8 __iomem *)(_vop_vq_config(desc) + ioread8(&desc->num_vq));
101 }
102
103 static inline u8 __iomem *
104 _vop_vq_configspace(struct mic_device_desc __iomem *desc)
105 {
106         return _vop_vq_features(desc) + ioread8(&desc->feature_len) * 2;
107 }
108
109 static inline unsigned
110 _vop_total_desc_size(struct mic_device_desc __iomem *desc)
111 {
112         return _vop_aligned_desc_size(desc) + sizeof(struct mic_device_ctrl);
113 }
114
115 /* This gets the device's feature bits. */
116 static u64 vop_get_features(struct virtio_device *vdev)
117 {
118         unsigned int i, bits;
119         u32 features = 0;
120         struct mic_device_desc __iomem *desc = to_vopvdev(vdev)->desc;
121         u8 __iomem *in_features = _vop_vq_features(desc);
122         int feature_len = ioread8(&desc->feature_len);
123
124         bits = min_t(unsigned, feature_len, sizeof(vdev->features)) * 8;
125         for (i = 0; i < bits; i++)
126                 if (ioread8(&in_features[i / 8]) & (BIT(i % 8)))
127                         features |= BIT(i);
128
129         return features;
130 }
131
132 static int vop_finalize_features(struct virtio_device *vdev)
133 {
134         unsigned int i, bits;
135         struct mic_device_desc __iomem *desc = to_vopvdev(vdev)->desc;
136         u8 feature_len = ioread8(&desc->feature_len);
137         /* Second half of bitmap is features we accept. */
138         u8 __iomem *out_features =
139                 _vop_vq_features(desc) + feature_len;
140
141         /* Give virtio_ring a chance to accept features. */
142         vring_transport_features(vdev);
143
144         memset_io(out_features, 0, feature_len);
145         bits = min_t(unsigned, feature_len,
146                      sizeof(vdev->features)) * 8;
147         for (i = 0; i < bits; i++) {
148                 if (__virtio_test_bit(vdev, i))
149                         iowrite8(ioread8(&out_features[i / 8]) | (1 << (i % 8)),
150                                  &out_features[i / 8]);
151         }
152         return 0;
153 }
154
155 /*
156  * Reading and writing elements in config space
157  */
158 static void vop_get(struct virtio_device *vdev, unsigned int offset,
159                     void *buf, unsigned len)
160 {
161         struct mic_device_desc __iomem *desc = to_vopvdev(vdev)->desc;
162
163         if (offset + len > ioread8(&desc->config_len))
164                 return;
165         memcpy_fromio(buf, _vop_vq_configspace(desc) + offset, len);
166 }
167
168 static void vop_set(struct virtio_device *vdev, unsigned int offset,
169                     const void *buf, unsigned len)
170 {
171         struct mic_device_desc __iomem *desc = to_vopvdev(vdev)->desc;
172
173         if (offset + len > ioread8(&desc->config_len))
174                 return;
175         memcpy_toio(_vop_vq_configspace(desc) + offset, buf, len);
176 }
177
178 /*
179  * The operations to get and set the status word just access the status
180  * field of the device descriptor. set_status also interrupts the host
181  * to tell about status changes.
182  */
183 static u8 vop_get_status(struct virtio_device *vdev)
184 {
185         return ioread8(&to_vopvdev(vdev)->desc->status);
186 }
187
188 static void vop_set_status(struct virtio_device *dev, u8 status)
189 {
190         struct _vop_vdev *vdev = to_vopvdev(dev);
191         struct vop_device *vpdev = vdev->vpdev;
192
193         if (!status)
194                 return;
195         iowrite8(status, &vdev->desc->status);
196         vpdev->hw_ops->send_intr(vpdev, vdev->c2h_vdev_db);
197 }
198
199 /* Inform host on a virtio device reset and wait for ack from host */
200 static void vop_reset_inform_host(struct virtio_device *dev)
201 {
202         struct _vop_vdev *vdev = to_vopvdev(dev);
203         struct mic_device_ctrl __iomem *dc = vdev->dc;
204         struct vop_device *vpdev = vdev->vpdev;
205         int retry;
206
207         iowrite8(0, &dc->host_ack);
208         iowrite8(1, &dc->vdev_reset);
209         vpdev->hw_ops->send_intr(vpdev, vdev->c2h_vdev_db);
210
211         /* Wait till host completes all card accesses and acks the reset */
212         for (retry = 100; retry--;) {
213                 if (ioread8(&dc->host_ack))
214                         break;
215                 msleep(100);
216         };
217
218         dev_dbg(_vop_dev(vdev), "%s: retry: %d\n", __func__, retry);
219
220         /* Reset status to 0 in case we timed out */
221         iowrite8(0, &vdev->desc->status);
222 }
223
224 static void vop_reset(struct virtio_device *dev)
225 {
226         struct _vop_vdev *vdev = to_vopvdev(dev);
227
228         dev_dbg(_vop_dev(vdev), "%s: virtio id %d\n",
229                 __func__, dev->id.device);
230
231         vop_reset_inform_host(dev);
232         complete_all(&vdev->reset_done);
233 }
234
235 /*
236  * The virtio_ring code calls this API when it wants to notify the Host.
237  */
238 static bool vop_notify(struct virtqueue *vq)
239 {
240         struct _vop_vdev *vdev = vq->priv;
241         struct vop_device *vpdev = vdev->vpdev;
242
243         vpdev->hw_ops->send_intr(vpdev, vdev->c2h_vdev_db);
244         return true;
245 }
246
247 static void vop_del_vq(struct virtqueue *vq, int n)
248 {
249         struct _vop_vdev *vdev = to_vopvdev(vq->vdev);
250         struct vring *vr = (struct vring *)(vq + 1);
251         struct vop_device *vpdev = vdev->vpdev;
252
253         dma_unmap_single(&vpdev->dev, vdev->used[n],
254                          vdev->used_size[n], DMA_BIDIRECTIONAL);
255         free_pages((unsigned long)vr->used, get_order(vdev->used_size[n]));
256         vring_del_virtqueue(vq);
257         vpdev->hw_ops->iounmap(vpdev, vdev->vr[n]);
258         vdev->vr[n] = NULL;
259 }
260
261 static void vop_del_vqs(struct virtio_device *dev)
262 {
263         struct _vop_vdev *vdev = to_vopvdev(dev);
264         struct virtqueue *vq, *n;
265         int idx = 0;
266
267         dev_dbg(_vop_dev(vdev), "%s\n", __func__);
268
269         list_for_each_entry_safe(vq, n, &dev->vqs, list)
270                 vop_del_vq(vq, idx++);
271 }
272
273 /*
274  * This routine will assign vring's allocated in host/io memory. Code in
275  * virtio_ring.c however continues to access this io memory as if it were local
276  * memory without io accessors.
277  */
278 static struct virtqueue *vop_find_vq(struct virtio_device *dev,
279                                      unsigned index,
280                                      void (*callback)(struct virtqueue *vq),
281                                      const char *name, bool ctx)
282 {
283         struct _vop_vdev *vdev = to_vopvdev(dev);
284         struct vop_device *vpdev = vdev->vpdev;
285         struct mic_vqconfig __iomem *vqconfig;
286         struct mic_vqconfig config;
287         struct virtqueue *vq;
288         void __iomem *va;
289         struct _mic_vring_info __iomem *info;
290         void *used;
291         int vr_size, _vr_size, err, magic;
292         struct vring *vr;
293         u8 type = ioread8(&vdev->desc->type);
294
295         if (index >= ioread8(&vdev->desc->num_vq))
296                 return ERR_PTR(-ENOENT);
297
298         if (!name)
299                 return ERR_PTR(-ENOENT);
300
301         /* First assign the vring's allocated in host memory */
302         vqconfig = _vop_vq_config(vdev->desc) + index;
303         memcpy_fromio(&config, vqconfig, sizeof(config));
304         _vr_size = vring_size(le16_to_cpu(config.num), MIC_VIRTIO_RING_ALIGN);
305         vr_size = PAGE_ALIGN(_vr_size + sizeof(struct _mic_vring_info));
306         va = vpdev->hw_ops->ioremap(vpdev, le64_to_cpu(config.address),
307                         vr_size);
308         if (!va)
309                 return ERR_PTR(-ENOMEM);
310         vdev->vr[index] = va;
311         memset_io(va, 0x0, _vr_size);
312         vq = vring_new_virtqueue(
313                                 index,
314                                 le16_to_cpu(config.num), MIC_VIRTIO_RING_ALIGN,
315                                 dev,
316                                 false,
317                                 ctx,
318                                 (void __force *)va, vop_notify, callback, name);
319         if (!vq) {
320                 err = -ENOMEM;
321                 goto unmap;
322         }
323         info = va + _vr_size;
324         magic = ioread32(&info->magic);
325
326         if (WARN(magic != MIC_MAGIC + type + index, "magic mismatch")) {
327                 err = -EIO;
328                 goto unmap;
329         }
330
331         /* Allocate and reassign used ring now */
332         vdev->used_size[index] = PAGE_ALIGN(sizeof(__u16) * 3 +
333                                              sizeof(struct vring_used_elem) *
334                                              le16_to_cpu(config.num));
335         used = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
336                                         get_order(vdev->used_size[index]));
337         if (!used) {
338                 err = -ENOMEM;
339                 dev_err(_vop_dev(vdev), "%s %d err %d\n",
340                         __func__, __LINE__, err);
341                 goto del_vq;
342         }
343         vdev->used[index] = dma_map_single(&vpdev->dev, used,
344                                             vdev->used_size[index],
345                                             DMA_BIDIRECTIONAL);
346         if (dma_mapping_error(&vpdev->dev, vdev->used[index])) {
347                 err = -ENOMEM;
348                 dev_err(_vop_dev(vdev), "%s %d err %d\n",
349                         __func__, __LINE__, err);
350                 goto free_used;
351         }
352         writeq(vdev->used[index], &vqconfig->used_address);
353         /*
354          * To reassign the used ring here we are directly accessing
355          * struct vring_virtqueue which is a private data structure
356          * in virtio_ring.c. At the minimum, a BUILD_BUG_ON() in
357          * vring_new_virtqueue() would ensure that
358          *  (&vq->vring == (struct vring *) (&vq->vq + 1));
359          */
360         vr = (struct vring *)(vq + 1);
361         vr->used = used;
362
363         vq->priv = vdev;
364         return vq;
365 free_used:
366         free_pages((unsigned long)used,
367                    get_order(vdev->used_size[index]));
368 del_vq:
369         vring_del_virtqueue(vq);
370 unmap:
371         vpdev->hw_ops->iounmap(vpdev, vdev->vr[index]);
372         return ERR_PTR(err);
373 }
374
375 static int vop_find_vqs(struct virtio_device *dev, unsigned nvqs,
376                         struct virtqueue *vqs[],
377                         vq_callback_t *callbacks[],
378                         const char * const names[], const bool *ctx,
379                         struct irq_affinity *desc)
380 {
381         struct _vop_vdev *vdev = to_vopvdev(dev);
382         struct vop_device *vpdev = vdev->vpdev;
383         struct mic_device_ctrl __iomem *dc = vdev->dc;
384         int i, err, retry;
385
386         /* We must have this many virtqueues. */
387         if (nvqs > ioread8(&vdev->desc->num_vq))
388                 return -ENOENT;
389
390         for (i = 0; i < nvqs; ++i) {
391                 dev_dbg(_vop_dev(vdev), "%s: %d: %s\n",
392                         __func__, i, names[i]);
393                 vqs[i] = vop_find_vq(dev, i, callbacks[i], names[i],
394                                      ctx ? ctx[i] : false);
395                 if (IS_ERR(vqs[i])) {
396                         err = PTR_ERR(vqs[i]);
397                         goto error;
398                 }
399         }
400
401         iowrite8(1, &dc->used_address_updated);
402         /*
403          * Send an interrupt to the host to inform it that used
404          * rings have been re-assigned.
405          */
406         vpdev->hw_ops->send_intr(vpdev, vdev->c2h_vdev_db);
407         for (retry = 100; --retry;) {
408                 if (!ioread8(&dc->used_address_updated))
409                         break;
410                 msleep(100);
411         };
412
413         dev_dbg(_vop_dev(vdev), "%s: retry: %d\n", __func__, retry);
414         if (!retry) {
415                 err = -ENODEV;
416                 goto error;
417         }
418
419         return 0;
420 error:
421         vop_del_vqs(dev);
422         return err;
423 }
424
425 /*
426  * The config ops structure as defined by virtio config
427  */
428 static struct virtio_config_ops vop_vq_config_ops = {
429         .get_features = vop_get_features,
430         .finalize_features = vop_finalize_features,
431         .get = vop_get,
432         .set = vop_set,
433         .get_status = vop_get_status,
434         .set_status = vop_set_status,
435         .reset = vop_reset,
436         .find_vqs = vop_find_vqs,
437         .del_vqs = vop_del_vqs,
438 };
439
440 static irqreturn_t vop_virtio_intr_handler(int irq, void *data)
441 {
442         struct _vop_vdev *vdev = data;
443         struct vop_device *vpdev = vdev->vpdev;
444         struct virtqueue *vq;
445
446         vpdev->hw_ops->ack_interrupt(vpdev, vdev->h2c_vdev_db);
447         list_for_each_entry(vq, &vdev->vdev.vqs, list)
448                 vring_interrupt(0, vq);
449
450         return IRQ_HANDLED;
451 }
452
453 static void vop_virtio_release_dev(struct device *_d)
454 {
455         /*
456          * No need for a release method similar to virtio PCI.
457          * Provide an empty one to avoid getting a warning from core.
458          */
459 }
460
461 /*
462  * adds a new device and register it with virtio
463  * appropriate drivers are loaded by the device model
464  */
465 static int _vop_add_device(struct mic_device_desc __iomem *d,
466                            unsigned int offset, struct vop_device *vpdev,
467                            int dnode)
468 {
469         struct _vop_vdev *vdev;
470         int ret;
471         u8 type = ioread8(&d->type);
472
473         vdev = kzalloc(sizeof(*vdev), GFP_KERNEL);
474         if (!vdev)
475                 return -ENOMEM;
476
477         vdev->vpdev = vpdev;
478         vdev->vdev.dev.parent = &vpdev->dev;
479         vdev->vdev.dev.release = vop_virtio_release_dev;
480         vdev->vdev.id.device = type;
481         vdev->vdev.config = &vop_vq_config_ops;
482         vdev->desc = d;
483         vdev->dc = (void __iomem *)d + _vop_aligned_desc_size(d);
484         vdev->dnode = dnode;
485         vdev->vdev.priv = (void *)(u64)dnode;
486         init_completion(&vdev->reset_done);
487
488         vdev->h2c_vdev_db = vpdev->hw_ops->next_db(vpdev);
489         vdev->virtio_cookie = vpdev->hw_ops->request_irq(vpdev,
490                         vop_virtio_intr_handler, "virtio intr",
491                         vdev, vdev->h2c_vdev_db);
492         if (IS_ERR(vdev->virtio_cookie)) {
493                 ret = PTR_ERR(vdev->virtio_cookie);
494                 goto kfree;
495         }
496         iowrite8((u8)vdev->h2c_vdev_db, &vdev->dc->h2c_vdev_db);
497         vdev->c2h_vdev_db = ioread8(&vdev->dc->c2h_vdev_db);
498
499         ret = register_virtio_device(&vdev->vdev);
500         if (ret) {
501                 dev_err(_vop_dev(vdev),
502                         "Failed to register vop device %u type %u\n",
503                         offset, type);
504                 goto free_irq;
505         }
506         writeq((u64)vdev, &vdev->dc->vdev);
507         dev_dbg(_vop_dev(vdev), "%s: registered vop device %u type %u vdev %p\n",
508                 __func__, offset, type, vdev);
509
510         return 0;
511
512 free_irq:
513         vpdev->hw_ops->free_irq(vpdev, vdev->virtio_cookie, vdev);
514 kfree:
515         kfree(vdev);
516         return ret;
517 }
518
519 /*
520  * match for a vop device with a specific desc pointer
521  */
522 static int vop_match_desc(struct device *dev, void *data)
523 {
524         struct virtio_device *_dev = dev_to_virtio(dev);
525         struct _vop_vdev *vdev = to_vopvdev(_dev);
526
527         return vdev->desc == (void __iomem *)data;
528 }
529
530 static void _vop_handle_config_change(struct mic_device_desc __iomem *d,
531                                       unsigned int offset,
532                                       struct vop_device *vpdev)
533 {
534         struct mic_device_ctrl __iomem *dc
535                 = (void __iomem *)d + _vop_aligned_desc_size(d);
536         struct _vop_vdev *vdev = (struct _vop_vdev *)readq(&dc->vdev);
537
538         if (ioread8(&dc->config_change) != MIC_VIRTIO_PARAM_CONFIG_CHANGED)
539                 return;
540
541         dev_dbg(&vpdev->dev, "%s %d\n", __func__, __LINE__);
542         virtio_config_changed(&vdev->vdev);
543         iowrite8(1, &dc->guest_ack);
544 }
545
546 /*
547  * removes a virtio device if a hot remove event has been
548  * requested by the host.
549  */
550 static int _vop_remove_device(struct mic_device_desc __iomem *d,
551                               unsigned int offset, struct vop_device *vpdev)
552 {
553         struct mic_device_ctrl __iomem *dc
554                 = (void __iomem *)d + _vop_aligned_desc_size(d);
555         struct _vop_vdev *vdev = (struct _vop_vdev *)readq(&dc->vdev);
556         u8 status;
557         int ret = -1;
558
559         if (ioread8(&dc->config_change) == MIC_VIRTIO_PARAM_DEV_REMOVE) {
560                 dev_dbg(&vpdev->dev,
561                         "%s %d config_change %d type %d vdev %p\n",
562                         __func__, __LINE__,
563                         ioread8(&dc->config_change), ioread8(&d->type), vdev);
564                 status = ioread8(&d->status);
565                 reinit_completion(&vdev->reset_done);
566                 unregister_virtio_device(&vdev->vdev);
567                 vpdev->hw_ops->free_irq(vpdev, vdev->virtio_cookie, vdev);
568                 iowrite8(-1, &dc->h2c_vdev_db);
569                 if (status & VIRTIO_CONFIG_S_DRIVER_OK)
570                         wait_for_completion(&vdev->reset_done);
571                 kfree(vdev);
572                 iowrite8(1, &dc->guest_ack);
573                 dev_dbg(&vpdev->dev, "%s %d guest_ack %d\n",
574                         __func__, __LINE__, ioread8(&dc->guest_ack));
575                 iowrite8(-1, &d->type);
576                 ret = 0;
577         }
578         return ret;
579 }
580
581 #define REMOVE_DEVICES true
582
583 static void _vop_scan_devices(void __iomem *dp, struct vop_device *vpdev,
584                               bool remove, int dnode)
585 {
586         s8 type;
587         unsigned int i;
588         struct mic_device_desc __iomem *d;
589         struct mic_device_ctrl __iomem *dc;
590         struct device *dev;
591         int ret;
592
593         for (i = sizeof(struct mic_bootparam);
594                         i < MIC_DP_SIZE; i += _vop_total_desc_size(d)) {
595                 d = dp + i;
596                 dc = (void __iomem *)d + _vop_aligned_desc_size(d);
597                 /*
598                  * This read barrier is paired with the corresponding write
599                  * barrier on the host which is inserted before adding or
600                  * removing a virtio device descriptor, by updating the type.
601                  */
602                 rmb();
603                 type = ioread8(&d->type);
604
605                 /* end of list */
606                 if (type == 0)
607                         break;
608
609                 if (type == -1)
610                         continue;
611
612                 /* device already exists */
613                 dev = device_find_child(&vpdev->dev, (void __force *)d,
614                                         vop_match_desc);
615                 if (dev) {
616                         if (remove)
617                                 iowrite8(MIC_VIRTIO_PARAM_DEV_REMOVE,
618                                          &dc->config_change);
619                         put_device(dev);
620                         _vop_handle_config_change(d, i, vpdev);
621                         ret = _vop_remove_device(d, i, vpdev);
622                         if (remove) {
623                                 iowrite8(0, &dc->config_change);
624                                 iowrite8(0, &dc->guest_ack);
625                         }
626                         continue;
627                 }
628
629                 /* new device */
630                 dev_dbg(&vpdev->dev, "%s %d Adding new virtio device %p\n",
631                         __func__, __LINE__, d);
632                 if (!remove)
633                         _vop_add_device(d, i, vpdev, dnode);
634         }
635 }
636
637 static void vop_scan_devices(struct vop_info *vi,
638                              struct vop_device *vpdev, bool remove)
639 {
640         void __iomem *dp = vpdev->hw_ops->get_remote_dp(vpdev);
641
642         if (!dp)
643                 return;
644         mutex_lock(&vi->vop_mutex);
645         _vop_scan_devices(dp, vpdev, remove, vpdev->dnode);
646         mutex_unlock(&vi->vop_mutex);
647 }
648
649 /*
650  * vop_hotplug_device tries to find changes in the device page.
651  */
652 static void vop_hotplug_devices(struct work_struct *work)
653 {
654         struct vop_info *vi = container_of(work, struct vop_info,
655                                              hotplug_work);
656
657         vop_scan_devices(vi, vi->vpdev, !REMOVE_DEVICES);
658 }
659
660 /*
661  * Interrupt handler for hot plug/config changes etc.
662  */
663 static irqreturn_t vop_extint_handler(int irq, void *data)
664 {
665         struct vop_info *vi = data;
666         struct mic_bootparam __iomem *bp;
667         struct vop_device *vpdev = vi->vpdev;
668
669         bp = vpdev->hw_ops->get_remote_dp(vpdev);
670         dev_dbg(&vpdev->dev, "%s %d hotplug work\n",
671                 __func__, __LINE__);
672         vpdev->hw_ops->ack_interrupt(vpdev, ioread8(&bp->h2c_config_db));
673         schedule_work(&vi->hotplug_work);
674         return IRQ_HANDLED;
675 }
676
677 static int vop_driver_probe(struct vop_device *vpdev)
678 {
679         struct vop_info *vi;
680         int rc;
681
682         vi = kzalloc(sizeof(*vi), GFP_KERNEL);
683         if (!vi) {
684                 rc = -ENOMEM;
685                 goto exit;
686         }
687         dev_set_drvdata(&vpdev->dev, vi);
688         vi->vpdev = vpdev;
689
690         mutex_init(&vi->vop_mutex);
691         INIT_WORK(&vi->hotplug_work, vop_hotplug_devices);
692         if (vpdev->dnode) {
693                 rc = vop_host_init(vi);
694                 if (rc < 0)
695                         goto free;
696         } else {
697                 struct mic_bootparam __iomem *bootparam;
698
699                 vop_scan_devices(vi, vpdev, !REMOVE_DEVICES);
700
701                 vi->h2c_config_db = vpdev->hw_ops->next_db(vpdev);
702                 vi->cookie = vpdev->hw_ops->request_irq(vpdev,
703                                                         vop_extint_handler,
704                                                         "virtio_config_intr",
705                                                         vi, vi->h2c_config_db);
706                 if (IS_ERR(vi->cookie)) {
707                         rc = PTR_ERR(vi->cookie);
708                         goto free;
709                 }
710                 bootparam = vpdev->hw_ops->get_remote_dp(vpdev);
711                 iowrite8(vi->h2c_config_db, &bootparam->h2c_config_db);
712         }
713         vop_init_debugfs(vi);
714         return 0;
715 free:
716         kfree(vi);
717 exit:
718         return rc;
719 }
720
721 static void vop_driver_remove(struct vop_device *vpdev)
722 {
723         struct vop_info *vi = dev_get_drvdata(&vpdev->dev);
724
725         if (vpdev->dnode) {
726                 vop_host_uninit(vi);
727         } else {
728                 struct mic_bootparam __iomem *bootparam =
729                         vpdev->hw_ops->get_remote_dp(vpdev);
730                 if (bootparam)
731                         iowrite8(-1, &bootparam->h2c_config_db);
732                 vpdev->hw_ops->free_irq(vpdev, vi->cookie, vi);
733                 flush_work(&vi->hotplug_work);
734                 vop_scan_devices(vi, vpdev, REMOVE_DEVICES);
735         }
736         vop_exit_debugfs(vi);
737         kfree(vi);
738 }
739
740 static struct vop_device_id id_table[] = {
741         { VOP_DEV_TRNSP, VOP_DEV_ANY_ID },
742         { 0 },
743 };
744
745 static struct vop_driver vop_driver = {
746         .driver.name =  KBUILD_MODNAME,
747         .driver.owner = THIS_MODULE,
748         .id_table = id_table,
749         .probe = vop_driver_probe,
750         .remove = vop_driver_remove,
751 };
752
753 module_vop_driver(vop_driver);
754
755 MODULE_DEVICE_TABLE(mbus, id_table);
756 MODULE_AUTHOR("Intel Corporation");
757 MODULE_DESCRIPTION("Intel(R) Virtio Over PCIe (VOP) driver");
758 MODULE_LICENSE("GPL v2");