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xenbus_client: Extend interface to support multi-page ring
[karo-tx-linux.git] / drivers / xen / xen-pciback / xenbus.c
1 /*
2  * PCI Backend Xenbus Setup - handles setup with frontend and xend
3  *
4  *   Author: Ryan Wilson <hap9@epoch.ncsc.mil>
5  */
6
7 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
8
9 #include <linux/module.h>
10 #include <linux/init.h>
11 #include <linux/list.h>
12 #include <linux/vmalloc.h>
13 #include <linux/workqueue.h>
14 #include <xen/xenbus.h>
15 #include <xen/events.h>
16 #include <asm/xen/pci.h>
17 #include "pciback.h"
18
19 #define INVALID_EVTCHN_IRQ  (-1)
20 struct workqueue_struct *xen_pcibk_wq;
21
22 static bool __read_mostly passthrough;
23 module_param(passthrough, bool, S_IRUGO);
24 MODULE_PARM_DESC(passthrough,
25         "Option to specify how to export PCI topology to guest:\n"\
26         " 0 - (default) Hide the true PCI topology and makes the frontend\n"\
27         "   there is a single PCI bus with only the exported devices on it.\n"\
28         "   For example, a device at 03:05.0 will be re-assigned to 00:00.0\n"\
29         "   while second device at 02:1a.1 will be re-assigned to 00:01.1.\n"\
30         " 1 - Passthrough provides a real view of the PCI topology to the\n"\
31         "   frontend (for example, a device at 06:01.b will still appear at\n"\
32         "   06:01.b to the frontend). This is similar to how Xen 2.0.x\n"\
33         "   exposed PCI devices to its driver domains. This may be required\n"\
34         "   for drivers which depend on finding their hardward in certain\n"\
35         "   bus/slot locations.");
36
37 static struct xen_pcibk_device *alloc_pdev(struct xenbus_device *xdev)
38 {
39         struct xen_pcibk_device *pdev;
40
41         pdev = kzalloc(sizeof(struct xen_pcibk_device), GFP_KERNEL);
42         if (pdev == NULL)
43                 goto out;
44         dev_dbg(&xdev->dev, "allocated pdev @ 0x%p\n", pdev);
45
46         pdev->xdev = xdev;
47         dev_set_drvdata(&xdev->dev, pdev);
48
49         mutex_init(&pdev->dev_lock);
50
51         pdev->sh_info = NULL;
52         pdev->evtchn_irq = INVALID_EVTCHN_IRQ;
53         pdev->be_watching = 0;
54
55         INIT_WORK(&pdev->op_work, xen_pcibk_do_op);
56
57         if (xen_pcibk_init_devices(pdev)) {
58                 kfree(pdev);
59                 pdev = NULL;
60         }
61 out:
62         return pdev;
63 }
64
65 static void xen_pcibk_disconnect(struct xen_pcibk_device *pdev)
66 {
67         mutex_lock(&pdev->dev_lock);
68         /* Ensure the guest can't trigger our handler before removing devices */
69         if (pdev->evtchn_irq != INVALID_EVTCHN_IRQ) {
70                 unbind_from_irqhandler(pdev->evtchn_irq, pdev);
71                 pdev->evtchn_irq = INVALID_EVTCHN_IRQ;
72         }
73
74         /* If the driver domain started an op, make sure we complete it
75          * before releasing the shared memory */
76
77         /* Note, the workqueue does not use spinlocks at all.*/
78         flush_workqueue(xen_pcibk_wq);
79
80         if (pdev->sh_info != NULL) {
81                 xenbus_unmap_ring_vfree(pdev->xdev, pdev->sh_info);
82                 pdev->sh_info = NULL;
83         }
84         mutex_unlock(&pdev->dev_lock);
85 }
86
87 static void free_pdev(struct xen_pcibk_device *pdev)
88 {
89         if (pdev->be_watching) {
90                 unregister_xenbus_watch(&pdev->be_watch);
91                 pdev->be_watching = 0;
92         }
93
94         xen_pcibk_disconnect(pdev);
95
96         /* N.B. This calls pcistub_put_pci_dev which does the FLR on all
97          * of the PCIe devices. */
98         xen_pcibk_release_devices(pdev);
99
100         dev_set_drvdata(&pdev->xdev->dev, NULL);
101         pdev->xdev = NULL;
102
103         kfree(pdev);
104 }
105
106 static int xen_pcibk_do_attach(struct xen_pcibk_device *pdev, int gnt_ref,
107                              int remote_evtchn)
108 {
109         int err = 0;
110         void *vaddr;
111
112         dev_dbg(&pdev->xdev->dev,
113                 "Attaching to frontend resources - gnt_ref=%d evtchn=%d\n",
114                 gnt_ref, remote_evtchn);
115
116         err = xenbus_map_ring_valloc(pdev->xdev, &gnt_ref, 1, &vaddr);
117         if (err < 0) {
118                 xenbus_dev_fatal(pdev->xdev, err,
119                                 "Error mapping other domain page in ours.");
120                 goto out;
121         }
122
123         pdev->sh_info = vaddr;
124
125         err = bind_interdomain_evtchn_to_irqhandler(
126                 pdev->xdev->otherend_id, remote_evtchn, xen_pcibk_handle_event,
127                 0, DRV_NAME, pdev);
128         if (err < 0) {
129                 xenbus_dev_fatal(pdev->xdev, err,
130                                  "Error binding event channel to IRQ");
131                 goto out;
132         }
133         pdev->evtchn_irq = err;
134         err = 0;
135
136         dev_dbg(&pdev->xdev->dev, "Attached!\n");
137 out:
138         return err;
139 }
140
141 static int xen_pcibk_attach(struct xen_pcibk_device *pdev)
142 {
143         int err = 0;
144         int gnt_ref, remote_evtchn;
145         char *magic = NULL;
146
147
148         mutex_lock(&pdev->dev_lock);
149         /* Make sure we only do this setup once */
150         if (xenbus_read_driver_state(pdev->xdev->nodename) !=
151             XenbusStateInitialised)
152                 goto out;
153
154         /* Wait for frontend to state that it has published the configuration */
155         if (xenbus_read_driver_state(pdev->xdev->otherend) !=
156             XenbusStateInitialised)
157                 goto out;
158
159         dev_dbg(&pdev->xdev->dev, "Reading frontend config\n");
160
161         err = xenbus_gather(XBT_NIL, pdev->xdev->otherend,
162                             "pci-op-ref", "%u", &gnt_ref,
163                             "event-channel", "%u", &remote_evtchn,
164                             "magic", NULL, &magic, NULL);
165         if (err) {
166                 /* If configuration didn't get read correctly, wait longer */
167                 xenbus_dev_fatal(pdev->xdev, err,
168                                  "Error reading configuration from frontend");
169                 goto out;
170         }
171
172         if (magic == NULL || strcmp(magic, XEN_PCI_MAGIC) != 0) {
173                 xenbus_dev_fatal(pdev->xdev, -EFAULT,
174                                  "version mismatch (%s/%s) with pcifront - "
175                                  "halting " DRV_NAME,
176                                  magic, XEN_PCI_MAGIC);
177                 err = -EFAULT;
178                 goto out;
179         }
180
181         err = xen_pcibk_do_attach(pdev, gnt_ref, remote_evtchn);
182         if (err)
183                 goto out;
184
185         dev_dbg(&pdev->xdev->dev, "Connecting...\n");
186
187         err = xenbus_switch_state(pdev->xdev, XenbusStateConnected);
188         if (err)
189                 xenbus_dev_fatal(pdev->xdev, err,
190                                  "Error switching to connected state!");
191
192         dev_dbg(&pdev->xdev->dev, "Connected? %d\n", err);
193 out:
194         mutex_unlock(&pdev->dev_lock);
195
196         kfree(magic);
197
198         return err;
199 }
200
201 static int xen_pcibk_publish_pci_dev(struct xen_pcibk_device *pdev,
202                                    unsigned int domain, unsigned int bus,
203                                    unsigned int devfn, unsigned int devid)
204 {
205         int err;
206         int len;
207         char str[64];
208
209         len = snprintf(str, sizeof(str), "vdev-%d", devid);
210         if (unlikely(len >= (sizeof(str) - 1))) {
211                 err = -ENOMEM;
212                 goto out;
213         }
214
215         /* Note: The PV protocol uses %02x, don't change it */
216         err = xenbus_printf(XBT_NIL, pdev->xdev->nodename, str,
217                             "%04x:%02x:%02x.%02x", domain, bus,
218                             PCI_SLOT(devfn), PCI_FUNC(devfn));
219
220 out:
221         return err;
222 }
223
224 static int xen_pcibk_export_device(struct xen_pcibk_device *pdev,
225                                  int domain, int bus, int slot, int func,
226                                  int devid)
227 {
228         struct pci_dev *dev;
229         int err = 0;
230
231         dev_dbg(&pdev->xdev->dev, "exporting dom %x bus %x slot %x func %x\n",
232                 domain, bus, slot, func);
233
234         dev = pcistub_get_pci_dev_by_slot(pdev, domain, bus, slot, func);
235         if (!dev) {
236                 err = -EINVAL;
237                 xenbus_dev_fatal(pdev->xdev, err,
238                                  "Couldn't locate PCI device "
239                                  "(%04x:%02x:%02x.%d)! "
240                                  "perhaps already in-use?",
241                                  domain, bus, slot, func);
242                 goto out;
243         }
244
245         err = xen_pcibk_add_pci_dev(pdev, dev, devid,
246                                     xen_pcibk_publish_pci_dev);
247         if (err)
248                 goto out;
249
250         dev_info(&dev->dev, "registering for %d\n", pdev->xdev->otherend_id);
251         if (xen_register_device_domain_owner(dev,
252                                              pdev->xdev->otherend_id) != 0) {
253                 dev_err(&dev->dev, "Stealing ownership from dom%d.\n",
254                         xen_find_device_domain_owner(dev));
255                 xen_unregister_device_domain_owner(dev);
256                 xen_register_device_domain_owner(dev, pdev->xdev->otherend_id);
257         }
258
259         /* TODO: It'd be nice to export a bridge and have all of its children
260          * get exported with it. This may be best done in xend (which will
261          * have to calculate resource usage anyway) but we probably want to
262          * put something in here to ensure that if a bridge gets given to a
263          * driver domain, that all devices under that bridge are not given
264          * to other driver domains (as he who controls the bridge can disable
265          * it and stop the other devices from working).
266          */
267 out:
268         return err;
269 }
270
271 static int xen_pcibk_remove_device(struct xen_pcibk_device *pdev,
272                                  int domain, int bus, int slot, int func)
273 {
274         int err = 0;
275         struct pci_dev *dev;
276
277         dev_dbg(&pdev->xdev->dev, "removing dom %x bus %x slot %x func %x\n",
278                 domain, bus, slot, func);
279
280         dev = xen_pcibk_get_pci_dev(pdev, domain, bus, PCI_DEVFN(slot, func));
281         if (!dev) {
282                 err = -EINVAL;
283                 dev_dbg(&pdev->xdev->dev, "Couldn't locate PCI device "
284                         "(%04x:%02x:%02x.%d)! not owned by this domain\n",
285                         domain, bus, slot, func);
286                 goto out;
287         }
288
289         dev_dbg(&dev->dev, "unregistering for %d\n", pdev->xdev->otherend_id);
290         xen_unregister_device_domain_owner(dev);
291
292         /* N.B. This ends up calling pcistub_put_pci_dev which ends up
293          * doing the FLR. */
294         xen_pcibk_release_pci_dev(pdev, dev, true /* use the lock. */);
295
296 out:
297         return err;
298 }
299
300 static int xen_pcibk_publish_pci_root(struct xen_pcibk_device *pdev,
301                                     unsigned int domain, unsigned int bus)
302 {
303         unsigned int d, b;
304         int i, root_num, len, err;
305         char str[64];
306
307         dev_dbg(&pdev->xdev->dev, "Publishing pci roots\n");
308
309         err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename,
310                            "root_num", "%d", &root_num);
311         if (err == 0 || err == -ENOENT)
312                 root_num = 0;
313         else if (err < 0)
314                 goto out;
315
316         /* Verify that we haven't already published this pci root */
317         for (i = 0; i < root_num; i++) {
318                 len = snprintf(str, sizeof(str), "root-%d", i);
319                 if (unlikely(len >= (sizeof(str) - 1))) {
320                         err = -ENOMEM;
321                         goto out;
322                 }
323
324                 err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename,
325                                    str, "%x:%x", &d, &b);
326                 if (err < 0)
327                         goto out;
328                 if (err != 2) {
329                         err = -EINVAL;
330                         goto out;
331                 }
332
333                 if (d == domain && b == bus) {
334                         err = 0;
335                         goto out;
336                 }
337         }
338
339         len = snprintf(str, sizeof(str), "root-%d", root_num);
340         if (unlikely(len >= (sizeof(str) - 1))) {
341                 err = -ENOMEM;
342                 goto out;
343         }
344
345         dev_dbg(&pdev->xdev->dev, "writing root %d at %04x:%02x\n",
346                 root_num, domain, bus);
347
348         err = xenbus_printf(XBT_NIL, pdev->xdev->nodename, str,
349                             "%04x:%02x", domain, bus);
350         if (err)
351                 goto out;
352
353         err = xenbus_printf(XBT_NIL, pdev->xdev->nodename,
354                             "root_num", "%d", (root_num + 1));
355
356 out:
357         return err;
358 }
359
360 static int xen_pcibk_reconfigure(struct xen_pcibk_device *pdev)
361 {
362         int err = 0;
363         int num_devs;
364         int domain, bus, slot, func;
365         int substate;
366         int i, len;
367         char state_str[64];
368         char dev_str[64];
369
370
371         dev_dbg(&pdev->xdev->dev, "Reconfiguring device ...\n");
372
373         mutex_lock(&pdev->dev_lock);
374         /* Make sure we only reconfigure once */
375         if (xenbus_read_driver_state(pdev->xdev->nodename) !=
376             XenbusStateReconfiguring)
377                 goto out;
378
379         err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename, "num_devs", "%d",
380                            &num_devs);
381         if (err != 1) {
382                 if (err >= 0)
383                         err = -EINVAL;
384                 xenbus_dev_fatal(pdev->xdev, err,
385                                  "Error reading number of devices");
386                 goto out;
387         }
388
389         for (i = 0; i < num_devs; i++) {
390                 len = snprintf(state_str, sizeof(state_str), "state-%d", i);
391                 if (unlikely(len >= (sizeof(state_str) - 1))) {
392                         err = -ENOMEM;
393                         xenbus_dev_fatal(pdev->xdev, err,
394                                          "String overflow while reading "
395                                          "configuration");
396                         goto out;
397                 }
398                 err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename, state_str,
399                                    "%d", &substate);
400                 if (err != 1)
401                         substate = XenbusStateUnknown;
402
403                 switch (substate) {
404                 case XenbusStateInitialising:
405                         dev_dbg(&pdev->xdev->dev, "Attaching dev-%d ...\n", i);
406
407                         len = snprintf(dev_str, sizeof(dev_str), "dev-%d", i);
408                         if (unlikely(len >= (sizeof(dev_str) - 1))) {
409                                 err = -ENOMEM;
410                                 xenbus_dev_fatal(pdev->xdev, err,
411                                                  "String overflow while "
412                                                  "reading configuration");
413                                 goto out;
414                         }
415                         err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename,
416                                            dev_str, "%x:%x:%x.%x",
417                                            &domain, &bus, &slot, &func);
418                         if (err < 0) {
419                                 xenbus_dev_fatal(pdev->xdev, err,
420                                                  "Error reading device "
421                                                  "configuration");
422                                 goto out;
423                         }
424                         if (err != 4) {
425                                 err = -EINVAL;
426                                 xenbus_dev_fatal(pdev->xdev, err,
427                                                  "Error parsing pci device "
428                                                  "configuration");
429                                 goto out;
430                         }
431
432                         err = xen_pcibk_export_device(pdev, domain, bus, slot,
433                                                     func, i);
434                         if (err)
435                                 goto out;
436
437                         /* Publish pci roots. */
438                         err = xen_pcibk_publish_pci_roots(pdev,
439                                                 xen_pcibk_publish_pci_root);
440                         if (err) {
441                                 xenbus_dev_fatal(pdev->xdev, err,
442                                                  "Error while publish PCI root"
443                                                  "buses for frontend");
444                                 goto out;
445                         }
446
447                         err = xenbus_printf(XBT_NIL, pdev->xdev->nodename,
448                                             state_str, "%d",
449                                             XenbusStateInitialised);
450                         if (err) {
451                                 xenbus_dev_fatal(pdev->xdev, err,
452                                                  "Error switching substate of "
453                                                  "dev-%d\n", i);
454                                 goto out;
455                         }
456                         break;
457
458                 case XenbusStateClosing:
459                         dev_dbg(&pdev->xdev->dev, "Detaching dev-%d ...\n", i);
460
461                         len = snprintf(dev_str, sizeof(dev_str), "vdev-%d", i);
462                         if (unlikely(len >= (sizeof(dev_str) - 1))) {
463                                 err = -ENOMEM;
464                                 xenbus_dev_fatal(pdev->xdev, err,
465                                                  "String overflow while "
466                                                  "reading configuration");
467                                 goto out;
468                         }
469                         err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename,
470                                            dev_str, "%x:%x:%x.%x",
471                                            &domain, &bus, &slot, &func);
472                         if (err < 0) {
473                                 xenbus_dev_fatal(pdev->xdev, err,
474                                                  "Error reading device "
475                                                  "configuration");
476                                 goto out;
477                         }
478                         if (err != 4) {
479                                 err = -EINVAL;
480                                 xenbus_dev_fatal(pdev->xdev, err,
481                                                  "Error parsing pci device "
482                                                  "configuration");
483                                 goto out;
484                         }
485
486                         err = xen_pcibk_remove_device(pdev, domain, bus, slot,
487                                                     func);
488                         if (err)
489                                 goto out;
490
491                         /* TODO: If at some point we implement support for pci
492                          * root hot-remove on pcifront side, we'll need to
493                          * remove unnecessary xenstore nodes of pci roots here.
494                          */
495
496                         break;
497
498                 default:
499                         break;
500                 }
501         }
502
503         err = xenbus_switch_state(pdev->xdev, XenbusStateReconfigured);
504         if (err) {
505                 xenbus_dev_fatal(pdev->xdev, err,
506                                  "Error switching to reconfigured state!");
507                 goto out;
508         }
509
510 out:
511         mutex_unlock(&pdev->dev_lock);
512         return 0;
513 }
514
515 static void xen_pcibk_frontend_changed(struct xenbus_device *xdev,
516                                      enum xenbus_state fe_state)
517 {
518         struct xen_pcibk_device *pdev = dev_get_drvdata(&xdev->dev);
519
520         dev_dbg(&xdev->dev, "fe state changed %d\n", fe_state);
521
522         switch (fe_state) {
523         case XenbusStateInitialised:
524                 xen_pcibk_attach(pdev);
525                 break;
526
527         case XenbusStateReconfiguring:
528                 xen_pcibk_reconfigure(pdev);
529                 break;
530
531         case XenbusStateConnected:
532                 /* pcifront switched its state from reconfiguring to connected.
533                  * Then switch to connected state.
534                  */
535                 xenbus_switch_state(xdev, XenbusStateConnected);
536                 break;
537
538         case XenbusStateClosing:
539                 xen_pcibk_disconnect(pdev);
540                 xenbus_switch_state(xdev, XenbusStateClosing);
541                 break;
542
543         case XenbusStateClosed:
544                 xen_pcibk_disconnect(pdev);
545                 xenbus_switch_state(xdev, XenbusStateClosed);
546                 if (xenbus_dev_is_online(xdev))
547                         break;
548                 /* fall through if not online */
549         case XenbusStateUnknown:
550                 dev_dbg(&xdev->dev, "frontend is gone! unregister device\n");
551                 device_unregister(&xdev->dev);
552                 break;
553
554         default:
555                 break;
556         }
557 }
558
559 static int xen_pcibk_setup_backend(struct xen_pcibk_device *pdev)
560 {
561         /* Get configuration from xend (if available now) */
562         int domain, bus, slot, func;
563         int err = 0;
564         int i, num_devs;
565         char dev_str[64];
566         char state_str[64];
567
568         mutex_lock(&pdev->dev_lock);
569         /* It's possible we could get the call to setup twice, so make sure
570          * we're not already connected.
571          */
572         if (xenbus_read_driver_state(pdev->xdev->nodename) !=
573             XenbusStateInitWait)
574                 goto out;
575
576         dev_dbg(&pdev->xdev->dev, "getting be setup\n");
577
578         err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename, "num_devs", "%d",
579                            &num_devs);
580         if (err != 1) {
581                 if (err >= 0)
582                         err = -EINVAL;
583                 xenbus_dev_fatal(pdev->xdev, err,
584                                  "Error reading number of devices");
585                 goto out;
586         }
587
588         for (i = 0; i < num_devs; i++) {
589                 int l = snprintf(dev_str, sizeof(dev_str), "dev-%d", i);
590                 if (unlikely(l >= (sizeof(dev_str) - 1))) {
591                         err = -ENOMEM;
592                         xenbus_dev_fatal(pdev->xdev, err,
593                                          "String overflow while reading "
594                                          "configuration");
595                         goto out;
596                 }
597
598                 err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename, dev_str,
599                                    "%x:%x:%x.%x", &domain, &bus, &slot, &func);
600                 if (err < 0) {
601                         xenbus_dev_fatal(pdev->xdev, err,
602                                          "Error reading device configuration");
603                         goto out;
604                 }
605                 if (err != 4) {
606                         err = -EINVAL;
607                         xenbus_dev_fatal(pdev->xdev, err,
608                                          "Error parsing pci device "
609                                          "configuration");
610                         goto out;
611                 }
612
613                 err = xen_pcibk_export_device(pdev, domain, bus, slot, func, i);
614                 if (err)
615                         goto out;
616
617                 /* Switch substate of this device. */
618                 l = snprintf(state_str, sizeof(state_str), "state-%d", i);
619                 if (unlikely(l >= (sizeof(state_str) - 1))) {
620                         err = -ENOMEM;
621                         xenbus_dev_fatal(pdev->xdev, err,
622                                          "String overflow while reading "
623                                          "configuration");
624                         goto out;
625                 }
626                 err = xenbus_printf(XBT_NIL, pdev->xdev->nodename, state_str,
627                                     "%d", XenbusStateInitialised);
628                 if (err) {
629                         xenbus_dev_fatal(pdev->xdev, err, "Error switching "
630                                          "substate of dev-%d\n", i);
631                         goto out;
632                 }
633         }
634
635         err = xen_pcibk_publish_pci_roots(pdev, xen_pcibk_publish_pci_root);
636         if (err) {
637                 xenbus_dev_fatal(pdev->xdev, err,
638                                  "Error while publish PCI root buses "
639                                  "for frontend");
640                 goto out;
641         }
642
643         err = xenbus_switch_state(pdev->xdev, XenbusStateInitialised);
644         if (err)
645                 xenbus_dev_fatal(pdev->xdev, err,
646                                  "Error switching to initialised state!");
647
648 out:
649         mutex_unlock(&pdev->dev_lock);
650         if (!err)
651                 /* see if pcifront is already configured (if not, we'll wait) */
652                 xen_pcibk_attach(pdev);
653         return err;
654 }
655
656 static void xen_pcibk_be_watch(struct xenbus_watch *watch,
657                              const char **vec, unsigned int len)
658 {
659         struct xen_pcibk_device *pdev =
660             container_of(watch, struct xen_pcibk_device, be_watch);
661
662         switch (xenbus_read_driver_state(pdev->xdev->nodename)) {
663         case XenbusStateInitWait:
664                 xen_pcibk_setup_backend(pdev);
665                 break;
666
667         default:
668                 break;
669         }
670 }
671
672 static int xen_pcibk_xenbus_probe(struct xenbus_device *dev,
673                                 const struct xenbus_device_id *id)
674 {
675         int err = 0;
676         struct xen_pcibk_device *pdev = alloc_pdev(dev);
677
678         if (pdev == NULL) {
679                 err = -ENOMEM;
680                 xenbus_dev_fatal(dev, err,
681                                  "Error allocating xen_pcibk_device struct");
682                 goto out;
683         }
684
685         /* wait for xend to configure us */
686         err = xenbus_switch_state(dev, XenbusStateInitWait);
687         if (err)
688                 goto out;
689
690         /* watch the backend node for backend configuration information */
691         err = xenbus_watch_path(dev, dev->nodename, &pdev->be_watch,
692                                 xen_pcibk_be_watch);
693         if (err)
694                 goto out;
695
696         pdev->be_watching = 1;
697
698         /* We need to force a call to our callback here in case
699          * xend already configured us!
700          */
701         xen_pcibk_be_watch(&pdev->be_watch, NULL, 0);
702
703 out:
704         return err;
705 }
706
707 static int xen_pcibk_xenbus_remove(struct xenbus_device *dev)
708 {
709         struct xen_pcibk_device *pdev = dev_get_drvdata(&dev->dev);
710
711         if (pdev != NULL)
712                 free_pdev(pdev);
713
714         return 0;
715 }
716
717 static const struct xenbus_device_id xen_pcibk_ids[] = {
718         {"pci"},
719         {""},
720 };
721
722 static struct xenbus_driver xen_pcibk_driver = {
723         .name                   = DRV_NAME,
724         .ids                    = xen_pcibk_ids,
725         .probe                  = xen_pcibk_xenbus_probe,
726         .remove                 = xen_pcibk_xenbus_remove,
727         .otherend_changed       = xen_pcibk_frontend_changed,
728 };
729
730 const struct xen_pcibk_backend *__read_mostly xen_pcibk_backend;
731
732 int __init xen_pcibk_xenbus_register(void)
733 {
734         xen_pcibk_wq = create_workqueue("xen_pciback_workqueue");
735         if (!xen_pcibk_wq) {
736                 pr_err("%s: create xen_pciback_workqueue failed\n", __func__);
737                 return -EFAULT;
738         }
739         xen_pcibk_backend = &xen_pcibk_vpci_backend;
740         if (passthrough)
741                 xen_pcibk_backend = &xen_pcibk_passthrough_backend;
742         pr_info("backend is %s\n", xen_pcibk_backend->name);
743         return xenbus_register_backend(&xen_pcibk_driver);
744 }
745
746 void __exit xen_pcibk_xenbus_unregister(void)
747 {
748         destroy_workqueue(xen_pcibk_wq);
749         xenbus_unregister_driver(&xen_pcibk_driver);
750 }