Merge branch 'topic/oxygen' into for-linus
[linux-2.6] / drivers / video / xen-fbfront.c
1 /*
2  * Xen para-virtual frame buffer device
3  *
4  * Copyright (C) 2005-2006 Anthony Liguori <aliguori@us.ibm.com>
5  * Copyright (C) 2006-2008 Red Hat, Inc., Markus Armbruster <armbru@redhat.com>
6  *
7  *  Based on linux/drivers/video/q40fb.c
8  *
9  *  This file is subject to the terms and conditions of the GNU General Public
10  *  License. See the file COPYING in the main directory of this archive for
11  *  more details.
12  */
13
14 /*
15  * TODO:
16  *
17  * Switch to grant tables when they become capable of dealing with the
18  * frame buffer.
19  */
20
21 #include <linux/console.h>
22 #include <linux/kernel.h>
23 #include <linux/errno.h>
24 #include <linux/fb.h>
25 #include <linux/module.h>
26 #include <linux/vmalloc.h>
27 #include <linux/mm.h>
28 #include <asm/xen/hypervisor.h>
29 #include <xen/events.h>
30 #include <xen/page.h>
31 #include <xen/interface/io/fbif.h>
32 #include <xen/interface/io/protocols.h>
33 #include <xen/xenbus.h>
34
35 struct xenfb_info {
36         unsigned char           *fb;
37         struct fb_info          *fb_info;
38         int                     x1, y1, x2, y2; /* dirty rectangle,
39                                                    protected by dirty_lock */
40         spinlock_t              dirty_lock;
41         int                     nr_pages;
42         int                     irq;
43         struct xenfb_page       *page;
44         unsigned long           *mfns;
45         int                     update_wanted; /* XENFB_TYPE_UPDATE wanted */
46         int                     feature_resize; /* XENFB_TYPE_RESIZE ok */
47         struct xenfb_resize     resize;         /* protected by resize_lock */
48         int                     resize_dpy;     /* ditto */
49         spinlock_t              resize_lock;
50
51         struct xenbus_device    *xbdev;
52 };
53
54 #define XENFB_DEFAULT_FB_LEN (XENFB_WIDTH * XENFB_HEIGHT * XENFB_DEPTH / 8)
55
56 enum { KPARAM_MEM, KPARAM_WIDTH, KPARAM_HEIGHT, KPARAM_CNT };
57 static int video[KPARAM_CNT] = { 2, XENFB_WIDTH, XENFB_HEIGHT };
58 module_param_array(video, int, NULL, 0);
59 MODULE_PARM_DESC(video,
60         "Video memory size in MB, width, height in pixels (default 2,800,600)");
61
62 static void xenfb_make_preferred_console(void);
63 static int xenfb_remove(struct xenbus_device *);
64 static void xenfb_init_shared_page(struct xenfb_info *, struct fb_info *);
65 static int xenfb_connect_backend(struct xenbus_device *, struct xenfb_info *);
66 static void xenfb_disconnect_backend(struct xenfb_info *);
67
68 static void xenfb_send_event(struct xenfb_info *info,
69                              union xenfb_out_event *event)
70 {
71         u32 prod;
72
73         prod = info->page->out_prod;
74         /* caller ensures !xenfb_queue_full() */
75         mb();                   /* ensure ring space available */
76         XENFB_OUT_RING_REF(info->page, prod) = *event;
77         wmb();                  /* ensure ring contents visible */
78         info->page->out_prod = prod + 1;
79
80         notify_remote_via_irq(info->irq);
81 }
82
83 static void xenfb_do_update(struct xenfb_info *info,
84                             int x, int y, int w, int h)
85 {
86         union xenfb_out_event event;
87
88         memset(&event, 0, sizeof(event));
89         event.type = XENFB_TYPE_UPDATE;
90         event.update.x = x;
91         event.update.y = y;
92         event.update.width = w;
93         event.update.height = h;
94
95         /* caller ensures !xenfb_queue_full() */
96         xenfb_send_event(info, &event);
97 }
98
99 static void xenfb_do_resize(struct xenfb_info *info)
100 {
101         union xenfb_out_event event;
102
103         memset(&event, 0, sizeof(event));
104         event.resize = info->resize;
105
106         /* caller ensures !xenfb_queue_full() */
107         xenfb_send_event(info, &event);
108 }
109
110 static int xenfb_queue_full(struct xenfb_info *info)
111 {
112         u32 cons, prod;
113
114         prod = info->page->out_prod;
115         cons = info->page->out_cons;
116         return prod - cons == XENFB_OUT_RING_LEN;
117 }
118
119 static void xenfb_handle_resize_dpy(struct xenfb_info *info)
120 {
121         unsigned long flags;
122
123         spin_lock_irqsave(&info->resize_lock, flags);
124         if (info->resize_dpy) {
125                 if (!xenfb_queue_full(info)) {
126                         info->resize_dpy = 0;
127                         xenfb_do_resize(info);
128                 }
129         }
130         spin_unlock_irqrestore(&info->resize_lock, flags);
131 }
132
133 static void xenfb_refresh(struct xenfb_info *info,
134                           int x1, int y1, int w, int h)
135 {
136         unsigned long flags;
137         int x2 = x1 + w - 1;
138         int y2 = y1 + h - 1;
139
140         xenfb_handle_resize_dpy(info);
141
142         if (!info->update_wanted)
143                 return;
144
145         spin_lock_irqsave(&info->dirty_lock, flags);
146
147         /* Combine with dirty rectangle: */
148         if (info->y1 < y1)
149                 y1 = info->y1;
150         if (info->y2 > y2)
151                 y2 = info->y2;
152         if (info->x1 < x1)
153                 x1 = info->x1;
154         if (info->x2 > x2)
155                 x2 = info->x2;
156
157         if (xenfb_queue_full(info)) {
158                 /* Can't send right now, stash it in the dirty rectangle */
159                 info->x1 = x1;
160                 info->x2 = x2;
161                 info->y1 = y1;
162                 info->y2 = y2;
163                 spin_unlock_irqrestore(&info->dirty_lock, flags);
164                 return;
165         }
166
167         /* Clear dirty rectangle: */
168         info->x1 = info->y1 = INT_MAX;
169         info->x2 = info->y2 = 0;
170
171         spin_unlock_irqrestore(&info->dirty_lock, flags);
172
173         if (x1 <= x2 && y1 <= y2)
174                 xenfb_do_update(info, x1, y1, x2 - x1 + 1, y2 - y1 + 1);
175 }
176
177 static void xenfb_deferred_io(struct fb_info *fb_info,
178                               struct list_head *pagelist)
179 {
180         struct xenfb_info *info = fb_info->par;
181         struct page *page;
182         unsigned long beg, end;
183         int y1, y2, miny, maxy;
184
185         miny = INT_MAX;
186         maxy = 0;
187         list_for_each_entry(page, pagelist, lru) {
188                 beg = page->index << PAGE_SHIFT;
189                 end = beg + PAGE_SIZE - 1;
190                 y1 = beg / fb_info->fix.line_length;
191                 y2 = end / fb_info->fix.line_length;
192                 if (y2 >= fb_info->var.yres)
193                         y2 = fb_info->var.yres - 1;
194                 if (miny > y1)
195                         miny = y1;
196                 if (maxy < y2)
197                         maxy = y2;
198         }
199         xenfb_refresh(info, 0, miny, fb_info->var.xres, maxy - miny + 1);
200 }
201
202 static struct fb_deferred_io xenfb_defio = {
203         .delay          = HZ / 20,
204         .deferred_io    = xenfb_deferred_io,
205 };
206
207 static int xenfb_setcolreg(unsigned regno, unsigned red, unsigned green,
208                            unsigned blue, unsigned transp,
209                            struct fb_info *info)
210 {
211         u32 v;
212
213         if (regno > info->cmap.len)
214                 return 1;
215
216 #define CNVT_TOHW(val, width) ((((val)<<(width))+0x7FFF-(val))>>16)
217         red = CNVT_TOHW(red, info->var.red.length);
218         green = CNVT_TOHW(green, info->var.green.length);
219         blue = CNVT_TOHW(blue, info->var.blue.length);
220         transp = CNVT_TOHW(transp, info->var.transp.length);
221 #undef CNVT_TOHW
222
223         v = (red << info->var.red.offset) |
224             (green << info->var.green.offset) |
225             (blue << info->var.blue.offset);
226
227         switch (info->var.bits_per_pixel) {
228         case 16:
229         case 24:
230         case 32:
231                 ((u32 *)info->pseudo_palette)[regno] = v;
232                 break;
233         }
234
235         return 0;
236 }
237
238 static void xenfb_fillrect(struct fb_info *p, const struct fb_fillrect *rect)
239 {
240         struct xenfb_info *info = p->par;
241
242         sys_fillrect(p, rect);
243         xenfb_refresh(info, rect->dx, rect->dy, rect->width, rect->height);
244 }
245
246 static void xenfb_imageblit(struct fb_info *p, const struct fb_image *image)
247 {
248         struct xenfb_info *info = p->par;
249
250         sys_imageblit(p, image);
251         xenfb_refresh(info, image->dx, image->dy, image->width, image->height);
252 }
253
254 static void xenfb_copyarea(struct fb_info *p, const struct fb_copyarea *area)
255 {
256         struct xenfb_info *info = p->par;
257
258         sys_copyarea(p, area);
259         xenfb_refresh(info, area->dx, area->dy, area->width, area->height);
260 }
261
262 static ssize_t xenfb_write(struct fb_info *p, const char __user *buf,
263                         size_t count, loff_t *ppos)
264 {
265         struct xenfb_info *info = p->par;
266         ssize_t res;
267
268         res = fb_sys_write(p, buf, count, ppos);
269         xenfb_refresh(info, 0, 0, info->page->width, info->page->height);
270         return res;
271 }
272
273 static int
274 xenfb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
275 {
276         struct xenfb_info *xenfb_info;
277         int required_mem_len;
278
279         xenfb_info = info->par;
280
281         if (!xenfb_info->feature_resize) {
282                 if (var->xres == video[KPARAM_WIDTH] &&
283                     var->yres == video[KPARAM_HEIGHT] &&
284                     var->bits_per_pixel == xenfb_info->page->depth) {
285                         return 0;
286                 }
287                 return -EINVAL;
288         }
289
290         /* Can't resize past initial width and height */
291         if (var->xres > video[KPARAM_WIDTH] || var->yres > video[KPARAM_HEIGHT])
292                 return -EINVAL;
293
294         required_mem_len = var->xres * var->yres * xenfb_info->page->depth / 8;
295         if (var->bits_per_pixel == xenfb_info->page->depth &&
296             var->xres <= info->fix.line_length / (XENFB_DEPTH / 8) &&
297             required_mem_len <= info->fix.smem_len) {
298                 var->xres_virtual = var->xres;
299                 var->yres_virtual = var->yres;
300                 return 0;
301         }
302         return -EINVAL;
303 }
304
305 static int xenfb_set_par(struct fb_info *info)
306 {
307         struct xenfb_info *xenfb_info;
308         unsigned long flags;
309
310         xenfb_info = info->par;
311
312         spin_lock_irqsave(&xenfb_info->resize_lock, flags);
313         xenfb_info->resize.type = XENFB_TYPE_RESIZE;
314         xenfb_info->resize.width = info->var.xres;
315         xenfb_info->resize.height = info->var.yres;
316         xenfb_info->resize.stride = info->fix.line_length;
317         xenfb_info->resize.depth = info->var.bits_per_pixel;
318         xenfb_info->resize.offset = 0;
319         xenfb_info->resize_dpy = 1;
320         spin_unlock_irqrestore(&xenfb_info->resize_lock, flags);
321         return 0;
322 }
323
324 static struct fb_ops xenfb_fb_ops = {
325         .owner          = THIS_MODULE,
326         .fb_read        = fb_sys_read,
327         .fb_write       = xenfb_write,
328         .fb_setcolreg   = xenfb_setcolreg,
329         .fb_fillrect    = xenfb_fillrect,
330         .fb_copyarea    = xenfb_copyarea,
331         .fb_imageblit   = xenfb_imageblit,
332         .fb_check_var   = xenfb_check_var,
333         .fb_set_par     = xenfb_set_par,
334 };
335
336 static irqreturn_t xenfb_event_handler(int rq, void *dev_id)
337 {
338         /*
339          * No in events recognized, simply ignore them all.
340          * If you need to recognize some, see xen-kbdfront's
341          * input_handler() for how to do that.
342          */
343         struct xenfb_info *info = dev_id;
344         struct xenfb_page *page = info->page;
345
346         if (page->in_cons != page->in_prod) {
347                 info->page->in_cons = info->page->in_prod;
348                 notify_remote_via_irq(info->irq);
349         }
350
351         /* Flush dirty rectangle: */
352         xenfb_refresh(info, INT_MAX, INT_MAX, -INT_MAX, -INT_MAX);
353
354         return IRQ_HANDLED;
355 }
356
357 static int __devinit xenfb_probe(struct xenbus_device *dev,
358                                  const struct xenbus_device_id *id)
359 {
360         struct xenfb_info *info;
361         struct fb_info *fb_info;
362         int fb_size;
363         int val;
364         int ret;
365
366         info = kzalloc(sizeof(*info), GFP_KERNEL);
367         if (info == NULL) {
368                 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
369                 return -ENOMEM;
370         }
371
372         /* Limit kernel param videoram amount to what is in xenstore */
373         if (xenbus_scanf(XBT_NIL, dev->otherend, "videoram", "%d", &val) == 1) {
374                 if (val < video[KPARAM_MEM])
375                         video[KPARAM_MEM] = val;
376         }
377
378         /* If requested res does not fit in available memory, use default */
379         fb_size = video[KPARAM_MEM] * 1024 * 1024;
380         if (video[KPARAM_WIDTH] * video[KPARAM_HEIGHT] * XENFB_DEPTH / 8
381             > fb_size) {
382                 video[KPARAM_WIDTH] = XENFB_WIDTH;
383                 video[KPARAM_HEIGHT] = XENFB_HEIGHT;
384                 fb_size = XENFB_DEFAULT_FB_LEN;
385         }
386
387         dev->dev.driver_data = info;
388         info->xbdev = dev;
389         info->irq = -1;
390         info->x1 = info->y1 = INT_MAX;
391         spin_lock_init(&info->dirty_lock);
392         spin_lock_init(&info->resize_lock);
393
394         info->fb = vmalloc(fb_size);
395         if (info->fb == NULL)
396                 goto error_nomem;
397         memset(info->fb, 0, fb_size);
398
399         info->nr_pages = (fb_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
400
401         info->mfns = vmalloc(sizeof(unsigned long) * info->nr_pages);
402         if (!info->mfns)
403                 goto error_nomem;
404
405         /* set up shared page */
406         info->page = (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
407         if (!info->page)
408                 goto error_nomem;
409
410         /* abusing framebuffer_alloc() to allocate pseudo_palette */
411         fb_info = framebuffer_alloc(sizeof(u32) * 256, NULL);
412         if (fb_info == NULL)
413                 goto error_nomem;
414
415         /* complete the abuse: */
416         fb_info->pseudo_palette = fb_info->par;
417         fb_info->par = info;
418
419         fb_info->screen_base = info->fb;
420
421         fb_info->fbops = &xenfb_fb_ops;
422         fb_info->var.xres_virtual = fb_info->var.xres = video[KPARAM_WIDTH];
423         fb_info->var.yres_virtual = fb_info->var.yres = video[KPARAM_HEIGHT];
424         fb_info->var.bits_per_pixel = XENFB_DEPTH;
425
426         fb_info->var.red = (struct fb_bitfield){16, 8, 0};
427         fb_info->var.green = (struct fb_bitfield){8, 8, 0};
428         fb_info->var.blue = (struct fb_bitfield){0, 8, 0};
429
430         fb_info->var.activate = FB_ACTIVATE_NOW;
431         fb_info->var.height = -1;
432         fb_info->var.width = -1;
433         fb_info->var.vmode = FB_VMODE_NONINTERLACED;
434
435         fb_info->fix.visual = FB_VISUAL_TRUECOLOR;
436         fb_info->fix.line_length = fb_info->var.xres * XENFB_DEPTH / 8;
437         fb_info->fix.smem_start = 0;
438         fb_info->fix.smem_len = fb_size;
439         strcpy(fb_info->fix.id, "xen");
440         fb_info->fix.type = FB_TYPE_PACKED_PIXELS;
441         fb_info->fix.accel = FB_ACCEL_NONE;
442
443         fb_info->flags = FBINFO_FLAG_DEFAULT;
444
445         ret = fb_alloc_cmap(&fb_info->cmap, 256, 0);
446         if (ret < 0) {
447                 framebuffer_release(fb_info);
448                 xenbus_dev_fatal(dev, ret, "fb_alloc_cmap");
449                 goto error;
450         }
451
452         fb_info->fbdefio = &xenfb_defio;
453         fb_deferred_io_init(fb_info);
454
455         xenfb_init_shared_page(info, fb_info);
456
457         ret = register_framebuffer(fb_info);
458         if (ret) {
459                 fb_deferred_io_cleanup(fb_info);
460                 fb_dealloc_cmap(&fb_info->cmap);
461                 framebuffer_release(fb_info);
462                 xenbus_dev_fatal(dev, ret, "register_framebuffer");
463                 goto error;
464         }
465         info->fb_info = fb_info;
466
467         ret = xenfb_connect_backend(dev, info);
468         if (ret < 0)
469                 goto error;
470
471         xenfb_make_preferred_console();
472         return 0;
473
474  error_nomem:
475         ret = -ENOMEM;
476         xenbus_dev_fatal(dev, ret, "allocating device memory");
477  error:
478         xenfb_remove(dev);
479         return ret;
480 }
481
482 static __devinit void
483 xenfb_make_preferred_console(void)
484 {
485         struct console *c;
486
487         if (console_set_on_cmdline)
488                 return;
489
490         acquire_console_sem();
491         for (c = console_drivers; c; c = c->next) {
492                 if (!strcmp(c->name, "tty") && c->index == 0)
493                         break;
494         }
495         release_console_sem();
496         if (c) {
497                 unregister_console(c);
498                 c->flags |= CON_CONSDEV;
499                 c->flags &= ~CON_PRINTBUFFER; /* don't print again */
500                 register_console(c);
501         }
502 }
503
504 static int xenfb_resume(struct xenbus_device *dev)
505 {
506         struct xenfb_info *info = dev->dev.driver_data;
507
508         xenfb_disconnect_backend(info);
509         xenfb_init_shared_page(info, info->fb_info);
510         return xenfb_connect_backend(dev, info);
511 }
512
513 static int xenfb_remove(struct xenbus_device *dev)
514 {
515         struct xenfb_info *info = dev->dev.driver_data;
516
517         xenfb_disconnect_backend(info);
518         if (info->fb_info) {
519                 fb_deferred_io_cleanup(info->fb_info);
520                 unregister_framebuffer(info->fb_info);
521                 fb_dealloc_cmap(&info->fb_info->cmap);
522                 framebuffer_release(info->fb_info);
523         }
524         free_page((unsigned long)info->page);
525         vfree(info->mfns);
526         vfree(info->fb);
527         kfree(info);
528
529         return 0;
530 }
531
532 static unsigned long vmalloc_to_mfn(void *address)
533 {
534         return pfn_to_mfn(vmalloc_to_pfn(address));
535 }
536
537 static void xenfb_init_shared_page(struct xenfb_info *info,
538                                    struct fb_info *fb_info)
539 {
540         int i;
541         int epd = PAGE_SIZE / sizeof(info->mfns[0]);
542
543         for (i = 0; i < info->nr_pages; i++)
544                 info->mfns[i] = vmalloc_to_mfn(info->fb + i * PAGE_SIZE);
545
546         for (i = 0; i * epd < info->nr_pages; i++)
547                 info->page->pd[i] = vmalloc_to_mfn(&info->mfns[i * epd]);
548
549         info->page->width = fb_info->var.xres;
550         info->page->height = fb_info->var.yres;
551         info->page->depth = fb_info->var.bits_per_pixel;
552         info->page->line_length = fb_info->fix.line_length;
553         info->page->mem_length = fb_info->fix.smem_len;
554         info->page->in_cons = info->page->in_prod = 0;
555         info->page->out_cons = info->page->out_prod = 0;
556 }
557
558 static int xenfb_connect_backend(struct xenbus_device *dev,
559                                  struct xenfb_info *info)
560 {
561         int ret, evtchn;
562         struct xenbus_transaction xbt;
563
564         ret = xenbus_alloc_evtchn(dev, &evtchn);
565         if (ret)
566                 return ret;
567         ret = bind_evtchn_to_irqhandler(evtchn, xenfb_event_handler,
568                                         0, dev->devicetype, info);
569         if (ret < 0) {
570                 xenbus_free_evtchn(dev, evtchn);
571                 xenbus_dev_fatal(dev, ret, "bind_evtchn_to_irqhandler");
572                 return ret;
573         }
574         info->irq = ret;
575
576  again:
577         ret = xenbus_transaction_start(&xbt);
578         if (ret) {
579                 xenbus_dev_fatal(dev, ret, "starting transaction");
580                 return ret;
581         }
582         ret = xenbus_printf(xbt, dev->nodename, "page-ref", "%lu",
583                             virt_to_mfn(info->page));
584         if (ret)
585                 goto error_xenbus;
586         ret = xenbus_printf(xbt, dev->nodename, "event-channel", "%u",
587                             evtchn);
588         if (ret)
589                 goto error_xenbus;
590         ret = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
591                             XEN_IO_PROTO_ABI_NATIVE);
592         if (ret)
593                 goto error_xenbus;
594         ret = xenbus_printf(xbt, dev->nodename, "feature-update", "1");
595         if (ret)
596                 goto error_xenbus;
597         ret = xenbus_transaction_end(xbt, 0);
598         if (ret) {
599                 if (ret == -EAGAIN)
600                         goto again;
601                 xenbus_dev_fatal(dev, ret, "completing transaction");
602                 return ret;
603         }
604
605         xenbus_switch_state(dev, XenbusStateInitialised);
606         return 0;
607
608  error_xenbus:
609         xenbus_transaction_end(xbt, 1);
610         xenbus_dev_fatal(dev, ret, "writing xenstore");
611         return ret;
612 }
613
614 static void xenfb_disconnect_backend(struct xenfb_info *info)
615 {
616         if (info->irq >= 0)
617                 unbind_from_irqhandler(info->irq, info);
618         info->irq = -1;
619 }
620
621 static void xenfb_backend_changed(struct xenbus_device *dev,
622                                   enum xenbus_state backend_state)
623 {
624         struct xenfb_info *info = dev->dev.driver_data;
625         int val;
626
627         switch (backend_state) {
628         case XenbusStateInitialising:
629         case XenbusStateInitialised:
630         case XenbusStateUnknown:
631         case XenbusStateClosed:
632                 break;
633
634         case XenbusStateInitWait:
635 InitWait:
636                 xenbus_switch_state(dev, XenbusStateConnected);
637                 break;
638
639         case XenbusStateConnected:
640                 /*
641                  * Work around xenbus race condition: If backend goes
642                  * through InitWait to Connected fast enough, we can
643                  * get Connected twice here.
644                  */
645                 if (dev->state != XenbusStateConnected)
646                         goto InitWait; /* no InitWait seen yet, fudge it */
647
648                 if (xenbus_scanf(XBT_NIL, info->xbdev->otherend,
649                                  "request-update", "%d", &val) < 0)
650                         val = 0;
651                 if (val)
652                         info->update_wanted = 1;
653
654                 if (xenbus_scanf(XBT_NIL, dev->otherend,
655                                  "feature-resize", "%d", &val) < 0)
656                         val = 0;
657                 info->feature_resize = val;
658                 break;
659
660         case XenbusStateClosing:
661                 xenbus_frontend_closed(dev);
662                 break;
663         }
664 }
665
666 static struct xenbus_device_id xenfb_ids[] = {
667         { "vfb" },
668         { "" }
669 };
670
671 static struct xenbus_driver xenfb_driver = {
672         .name = "vfb",
673         .owner = THIS_MODULE,
674         .ids = xenfb_ids,
675         .probe = xenfb_probe,
676         .remove = xenfb_remove,
677         .resume = xenfb_resume,
678         .otherend_changed = xenfb_backend_changed,
679 };
680
681 static int __init xenfb_init(void)
682 {
683         if (!xen_domain())
684                 return -ENODEV;
685
686         /* Nothing to do if running in dom0. */
687         if (xen_initial_domain())
688                 return -ENODEV;
689
690         return xenbus_register_frontend(&xenfb_driver);
691 }
692
693 static void __exit xenfb_cleanup(void)
694 {
695         xenbus_unregister_driver(&xenfb_driver);
696 }
697
698 module_init(xenfb_init);
699 module_exit(xenfb_cleanup);
700
701 MODULE_DESCRIPTION("Xen virtual framebuffer device frontend");
702 MODULE_LICENSE("GPL");
703 MODULE_ALIAS("xen:vfb");