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/slab.h>
27#include <linux/vmalloc.h>
28#include <linux/mm.h>
29
30#include <asm/xen/hypervisor.h>
31
32#include <xen/xen.h>
33#include <xen/events.h>
34#include <xen/page.h>
35#include <xen/interface/io/fbif.h>
36#include <xen/interface/io/protocols.h>
37#include <xen/xenbus.h>
38#include <xen/platform_pci.h>
39
40struct xenfb_info {
41	unsigned char		*fb;
42	struct fb_info		*fb_info;
43	int			x1, y1, x2, y2;	/* dirty rectangle,
44						   protected by dirty_lock */
45	spinlock_t		dirty_lock;
46	int			nr_pages;
47	int			irq;
48	struct xenfb_page	*page;
49	unsigned long 		*mfns;
50	int			update_wanted; /* XENFB_TYPE_UPDATE wanted */
51	int			feature_resize; /* XENFB_TYPE_RESIZE ok */
52	struct xenfb_resize	resize;		/* protected by resize_lock */
53	int			resize_dpy;	/* ditto */
54	spinlock_t		resize_lock;
55
56	struct xenbus_device	*xbdev;
57};
58
59#define XENFB_DEFAULT_FB_LEN (XENFB_WIDTH * XENFB_HEIGHT * XENFB_DEPTH / 8)
60
61enum { KPARAM_MEM, KPARAM_WIDTH, KPARAM_HEIGHT, KPARAM_CNT };
62static int video[KPARAM_CNT] = { 2, XENFB_WIDTH, XENFB_HEIGHT };
63module_param_array(video, int, NULL, 0);
64MODULE_PARM_DESC(video,
65	"Video memory size in MB, width, height in pixels (default 2,800,600)");
66
67static void xenfb_make_preferred_console(void);
68static int xenfb_remove(struct xenbus_device *);
69static void xenfb_init_shared_page(struct xenfb_info *, struct fb_info *);
70static int xenfb_connect_backend(struct xenbus_device *, struct xenfb_info *);
71static void xenfb_disconnect_backend(struct xenfb_info *);
72
73static void xenfb_send_event(struct xenfb_info *info,
74			     union xenfb_out_event *event)
75{
76	u32 prod;
77
78	prod = info->page->out_prod;
79	/* caller ensures !xenfb_queue_full() */
80	mb();			/* ensure ring space available */
81	XENFB_OUT_RING_REF(info->page, prod) = *event;
82	wmb();			/* ensure ring contents visible */
83	info->page->out_prod = prod + 1;
84
85	notify_remote_via_irq(info->irq);
86}
87
88static void xenfb_do_update(struct xenfb_info *info,
89			    int x, int y, int w, int h)
90{
91	union xenfb_out_event event;
92
93	memset(&event, 0, sizeof(event));
94	event.type = XENFB_TYPE_UPDATE;
95	event.update.x = x;
96	event.update.y = y;
97	event.update.width = w;
98	event.update.height = h;
99
100	/* caller ensures !xenfb_queue_full() */
101	xenfb_send_event(info, &event);
102}
103
104static void xenfb_do_resize(struct xenfb_info *info)
105{
106	union xenfb_out_event event;
107
108	memset(&event, 0, sizeof(event));
109	event.resize = info->resize;
110
111	/* caller ensures !xenfb_queue_full() */
112	xenfb_send_event(info, &event);
113}
114
115static int xenfb_queue_full(struct xenfb_info *info)
116{
117	u32 cons, prod;
118
119	prod = info->page->out_prod;
120	cons = info->page->out_cons;
121	return prod - cons == XENFB_OUT_RING_LEN;
122}
123
124static void xenfb_handle_resize_dpy(struct xenfb_info *info)
125{
126	unsigned long flags;
127
128	spin_lock_irqsave(&info->resize_lock, flags);
129	if (info->resize_dpy) {
130		if (!xenfb_queue_full(info)) {
131			info->resize_dpy = 0;
132			xenfb_do_resize(info);
133		}
134	}
135	spin_unlock_irqrestore(&info->resize_lock, flags);
136}
137
138static void xenfb_refresh(struct xenfb_info *info,
139			  int x1, int y1, int w, int h)
140{
141	unsigned long flags;
142	int x2 = x1 + w - 1;
143	int y2 = y1 + h - 1;
144
145	xenfb_handle_resize_dpy(info);
146
147	if (!info->update_wanted)
148		return;
149
150	spin_lock_irqsave(&info->dirty_lock, flags);
151
152	/* Combine with dirty rectangle: */
153	if (info->y1 < y1)
154		y1 = info->y1;
155	if (info->y2 > y2)
156		y2 = info->y2;
157	if (info->x1 < x1)
158		x1 = info->x1;
159	if (info->x2 > x2)
160		x2 = info->x2;
161
162	if (xenfb_queue_full(info)) {
163		/* Can't send right now, stash it in the dirty rectangle */
164		info->x1 = x1;
165		info->x2 = x2;
166		info->y1 = y1;
167		info->y2 = y2;
168		spin_unlock_irqrestore(&info->dirty_lock, flags);
169		return;
170	}
171
172	/* Clear dirty rectangle: */
173	info->x1 = info->y1 = INT_MAX;
174	info->x2 = info->y2 = 0;
175
176	spin_unlock_irqrestore(&info->dirty_lock, flags);
177
178	if (x1 <= x2 && y1 <= y2)
179		xenfb_do_update(info, x1, y1, x2 - x1 + 1, y2 - y1 + 1);
180}
181
182static void xenfb_deferred_io(struct fb_info *fb_info,
183			      struct list_head *pagelist)
184{
185	struct xenfb_info *info = fb_info->par;
186	struct page *page;
187	unsigned long beg, end;
188	int y1, y2, miny, maxy;
189
190	miny = INT_MAX;
191	maxy = 0;
192	list_for_each_entry(page, pagelist, lru) {
193		beg = page->index << PAGE_SHIFT;
194		end = beg + PAGE_SIZE - 1;
195		y1 = beg / fb_info->fix.line_length;
196		y2 = end / fb_info->fix.line_length;
197		if (y2 >= fb_info->var.yres)
198			y2 = fb_info->var.yres - 1;
199		if (miny > y1)
200			miny = y1;
201		if (maxy < y2)
202			maxy = y2;
203	}
204	xenfb_refresh(info, 0, miny, fb_info->var.xres, maxy - miny + 1);
205}
206
207static struct fb_deferred_io xenfb_defio = {
208	.delay		= HZ / 20,
209	.deferred_io	= xenfb_deferred_io,
210};
211
212static int xenfb_setcolreg(unsigned regno, unsigned red, unsigned green,
213			   unsigned blue, unsigned transp,
214			   struct fb_info *info)
215{
216	u32 v;
217
218	if (regno > info->cmap.len)
219		return 1;
220
221#define CNVT_TOHW(val, width) ((((val)<<(width))+0x7FFF-(val))>>16)
222	red = CNVT_TOHW(red, info->var.red.length);
223	green = CNVT_TOHW(green, info->var.green.length);
224	blue = CNVT_TOHW(blue, info->var.blue.length);
225	transp = CNVT_TOHW(transp, info->var.transp.length);
226#undef CNVT_TOHW
227
228	v = (red << info->var.red.offset) |
229	    (green << info->var.green.offset) |
230	    (blue << info->var.blue.offset);
231
232	switch (info->var.bits_per_pixel) {
233	case 16:
234	case 24:
235	case 32:
236		((u32 *)info->pseudo_palette)[regno] = v;
237		break;
238	}
239
240	return 0;
241}
242
243static void xenfb_fillrect(struct fb_info *p, const struct fb_fillrect *rect)
244{
245	struct xenfb_info *info = p->par;
246
247	sys_fillrect(p, rect);
248	xenfb_refresh(info, rect->dx, rect->dy, rect->width, rect->height);
249}
250
251static void xenfb_imageblit(struct fb_info *p, const struct fb_image *image)
252{
253	struct xenfb_info *info = p->par;
254
255	sys_imageblit(p, image);
256	xenfb_refresh(info, image->dx, image->dy, image->width, image->height);
257}
258
259static void xenfb_copyarea(struct fb_info *p, const struct fb_copyarea *area)
260{
261	struct xenfb_info *info = p->par;
262
263	sys_copyarea(p, area);
264	xenfb_refresh(info, area->dx, area->dy, area->width, area->height);
265}
266
267static ssize_t xenfb_write(struct fb_info *p, const char __user *buf,
268			size_t count, loff_t *ppos)
269{
270	struct xenfb_info *info = p->par;
271	ssize_t res;
272
273	res = fb_sys_write(p, buf, count, ppos);
274	xenfb_refresh(info, 0, 0, info->page->width, info->page->height);
275	return res;
276}
277
278static int
279xenfb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
280{
281	struct xenfb_info *xenfb_info;
282	int required_mem_len;
283
284	xenfb_info = info->par;
285
286	if (!xenfb_info->feature_resize) {
287		if (var->xres == video[KPARAM_WIDTH] &&
288		    var->yres == video[KPARAM_HEIGHT] &&
289		    var->bits_per_pixel == xenfb_info->page->depth) {
290			return 0;
291		}
292		return -EINVAL;
293	}
294
295	/* Can't resize past initial width and height */
296	if (var->xres > video[KPARAM_WIDTH] || var->yres > video[KPARAM_HEIGHT])
297		return -EINVAL;
298
299	required_mem_len = var->xres * var->yres * xenfb_info->page->depth / 8;
300	if (var->bits_per_pixel == xenfb_info->page->depth &&
301	    var->xres <= info->fix.line_length / (XENFB_DEPTH / 8) &&
302	    required_mem_len <= info->fix.smem_len) {
303		var->xres_virtual = var->xres;
304		var->yres_virtual = var->yres;
305		return 0;
306	}
307	return -EINVAL;
308}
309
310static int xenfb_set_par(struct fb_info *info)
311{
312	struct xenfb_info *xenfb_info;
313	unsigned long flags;
314
315	xenfb_info = info->par;
316
317	spin_lock_irqsave(&xenfb_info->resize_lock, flags);
318	xenfb_info->resize.type = XENFB_TYPE_RESIZE;
319	xenfb_info->resize.width = info->var.xres;
320	xenfb_info->resize.height = info->var.yres;
321	xenfb_info->resize.stride = info->fix.line_length;
322	xenfb_info->resize.depth = info->var.bits_per_pixel;
323	xenfb_info->resize.offset = 0;
324	xenfb_info->resize_dpy = 1;
325	spin_unlock_irqrestore(&xenfb_info->resize_lock, flags);
326	return 0;
327}
328
329static struct fb_ops xenfb_fb_ops = {
330	.owner		= THIS_MODULE,
331	.fb_read	= fb_sys_read,
332	.fb_write	= xenfb_write,
333	.fb_setcolreg	= xenfb_setcolreg,
334	.fb_fillrect	= xenfb_fillrect,
335	.fb_copyarea	= xenfb_copyarea,
336	.fb_imageblit	= xenfb_imageblit,
337	.fb_check_var	= xenfb_check_var,
338	.fb_set_par     = xenfb_set_par,
339};
340
341static irqreturn_t xenfb_event_handler(int rq, void *dev_id)
342{
343	/*
344	 * No in events recognized, simply ignore them all.
345	 * If you need to recognize some, see xen-kbdfront's
346	 * input_handler() for how to do that.
347	 */
348	struct xenfb_info *info = dev_id;
349	struct xenfb_page *page = info->page;
350
351	if (page->in_cons != page->in_prod) {
352		info->page->in_cons = info->page->in_prod;
353		notify_remote_via_irq(info->irq);
354	}
355
356	/* Flush dirty rectangle: */
357	xenfb_refresh(info, INT_MAX, INT_MAX, -INT_MAX, -INT_MAX);
358
359	return IRQ_HANDLED;
360}
361
362static int xenfb_probe(struct xenbus_device *dev,
363		       const struct xenbus_device_id *id)
364{
365	struct xenfb_info *info;
366	struct fb_info *fb_info;
367	int fb_size;
368	int val;
369	int ret = 0;
370
371	info = kzalloc(sizeof(*info), GFP_KERNEL);
372	if (info == NULL) {
373		xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
374		return -ENOMEM;
375	}
376
377	/* Limit kernel param videoram amount to what is in xenstore */
378	if (xenbus_scanf(XBT_NIL, dev->otherend, "videoram", "%d", &val) == 1) {
379		if (val < video[KPARAM_MEM])
380			video[KPARAM_MEM] = val;
381	}
382
383	/* If requested res does not fit in available memory, use default */
384	fb_size = video[KPARAM_MEM] * 1024 * 1024;
385	if (video[KPARAM_WIDTH] * video[KPARAM_HEIGHT] * XENFB_DEPTH / 8
386	    > fb_size) {
387		video[KPARAM_WIDTH] = XENFB_WIDTH;
388		video[KPARAM_HEIGHT] = XENFB_HEIGHT;
389		fb_size = XENFB_DEFAULT_FB_LEN;
390	}
391
392	dev_set_drvdata(&dev->dev, info);
393	info->xbdev = dev;
394	info->irq = -1;
395	info->x1 = info->y1 = INT_MAX;
396	spin_lock_init(&info->dirty_lock);
397	spin_lock_init(&info->resize_lock);
398
399	info->fb = vzalloc(fb_size);
400	if (info->fb == NULL)
401		goto error_nomem;
402
403	info->nr_pages = (fb_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
404
405	info->mfns = vmalloc(sizeof(unsigned long) * info->nr_pages);
406	if (!info->mfns)
407		goto error_nomem;
408
409	/* set up shared page */
410	info->page = (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
411	if (!info->page)
412		goto error_nomem;
413
414	/* abusing framebuffer_alloc() to allocate pseudo_palette */
415	fb_info = framebuffer_alloc(sizeof(u32) * 256, NULL);
416	if (fb_info == NULL)
417		goto error_nomem;
418
419	/* complete the abuse: */
420	fb_info->pseudo_palette = fb_info->par;
421	fb_info->par = info;
422
423	fb_info->screen_base = info->fb;
424
425	fb_info->fbops = &xenfb_fb_ops;
426	fb_info->var.xres_virtual = fb_info->var.xres = video[KPARAM_WIDTH];
427	fb_info->var.yres_virtual = fb_info->var.yres = video[KPARAM_HEIGHT];
428	fb_info->var.bits_per_pixel = XENFB_DEPTH;
429
430	fb_info->var.red = (struct fb_bitfield){16, 8, 0};
431	fb_info->var.green = (struct fb_bitfield){8, 8, 0};
432	fb_info->var.blue = (struct fb_bitfield){0, 8, 0};
433
434	fb_info->var.activate = FB_ACTIVATE_NOW;
435	fb_info->var.height = -1;
436	fb_info->var.width = -1;
437	fb_info->var.vmode = FB_VMODE_NONINTERLACED;
438
439	fb_info->fix.visual = FB_VISUAL_TRUECOLOR;
440	fb_info->fix.line_length = fb_info->var.xres * XENFB_DEPTH / 8;
441	fb_info->fix.smem_start = 0;
442	fb_info->fix.smem_len = fb_size;
443	strcpy(fb_info->fix.id, "xen");
444	fb_info->fix.type = FB_TYPE_PACKED_PIXELS;
445	fb_info->fix.accel = FB_ACCEL_NONE;
446
447	fb_info->flags = FBINFO_FLAG_DEFAULT | FBINFO_VIRTFB;
448
449	ret = fb_alloc_cmap(&fb_info->cmap, 256, 0);
450	if (ret < 0) {
451		framebuffer_release(fb_info);
452		xenbus_dev_fatal(dev, ret, "fb_alloc_cmap");
453		goto error;
454	}
455
456	fb_info->fbdefio = &xenfb_defio;
457	fb_deferred_io_init(fb_info);
458
459	xenfb_init_shared_page(info, fb_info);
460
461	ret = xenfb_connect_backend(dev, info);
462	if (ret < 0) {
463		xenbus_dev_fatal(dev, ret, "xenfb_connect_backend");
464		goto error_fb;
465	}
466
467	ret = register_framebuffer(fb_info);
468	if (ret) {
469		xenbus_dev_fatal(dev, ret, "register_framebuffer");
470		goto error_fb;
471	}
472	info->fb_info = fb_info;
473
474	xenfb_make_preferred_console();
475	return 0;
476
477error_fb:
478	fb_deferred_io_cleanup(fb_info);
479	fb_dealloc_cmap(&fb_info->cmap);
480	framebuffer_release(fb_info);
481error_nomem:
482	if (!ret) {
483		ret = -ENOMEM;
484		xenbus_dev_fatal(dev, ret, "allocating device memory");
485	}
486error:
487	xenfb_remove(dev);
488	return ret;
489}
490
491static void xenfb_make_preferred_console(void)
492{
493	struct console *c;
494
495	if (console_set_on_cmdline)
496		return;
497
498	console_lock();
499	for_each_console(c) {
500		if (!strcmp(c->name, "tty") && c->index == 0)
501			break;
502	}
503	console_unlock();
504	if (c) {
505		unregister_console(c);
506		c->flags |= CON_CONSDEV;
507		c->flags &= ~CON_PRINTBUFFER; /* don't print again */
508		register_console(c);
509	}
510}
511
512static int xenfb_resume(struct xenbus_device *dev)
513{
514	struct xenfb_info *info = dev_get_drvdata(&dev->dev);
515
516	xenfb_disconnect_backend(info);
517	xenfb_init_shared_page(info, info->fb_info);
518	return xenfb_connect_backend(dev, info);
519}
520
521static int xenfb_remove(struct xenbus_device *dev)
522{
523	struct xenfb_info *info = dev_get_drvdata(&dev->dev);
524
525	xenfb_disconnect_backend(info);
526	if (info->fb_info) {
527		fb_deferred_io_cleanup(info->fb_info);
528		unregister_framebuffer(info->fb_info);
529		fb_dealloc_cmap(&info->fb_info->cmap);
530		framebuffer_release(info->fb_info);
531	}
532	free_page((unsigned long)info->page);
533	vfree(info->mfns);
534	vfree(info->fb);
535	kfree(info);
536
537	return 0;
538}
539
540static unsigned long vmalloc_to_mfn(void *address)
541{
542	return pfn_to_mfn(vmalloc_to_pfn(address));
543}
544
545static void xenfb_init_shared_page(struct xenfb_info *info,
546				   struct fb_info *fb_info)
547{
548	int i;
549	int epd = PAGE_SIZE / sizeof(info->mfns[0]);
550
551	for (i = 0; i < info->nr_pages; i++)
552		info->mfns[i] = vmalloc_to_mfn(info->fb + i * PAGE_SIZE);
553
554	for (i = 0; i * epd < info->nr_pages; i++)
555		info->page->pd[i] = vmalloc_to_mfn(&info->mfns[i * epd]);
556
557	info->page->width = fb_info->var.xres;
558	info->page->height = fb_info->var.yres;
559	info->page->depth = fb_info->var.bits_per_pixel;
560	info->page->line_length = fb_info->fix.line_length;
561	info->page->mem_length = fb_info->fix.smem_len;
562	info->page->in_cons = info->page->in_prod = 0;
563	info->page->out_cons = info->page->out_prod = 0;
564}
565
566static int xenfb_connect_backend(struct xenbus_device *dev,
567				 struct xenfb_info *info)
568{
569	int ret, evtchn, irq;
570	struct xenbus_transaction xbt;
571
572	ret = xenbus_alloc_evtchn(dev, &evtchn);
573	if (ret)
574		return ret;
575	irq = bind_evtchn_to_irqhandler(evtchn, xenfb_event_handler,
576					0, dev->devicetype, info);
577	if (irq < 0) {
578		xenbus_free_evtchn(dev, evtchn);
579		xenbus_dev_fatal(dev, ret, "bind_evtchn_to_irqhandler");
580		return irq;
581	}
582 again:
583	ret = xenbus_transaction_start(&xbt);
584	if (ret) {
585		xenbus_dev_fatal(dev, ret, "starting transaction");
586		goto unbind_irq;
587	}
588	ret = xenbus_printf(xbt, dev->nodename, "page-ref", "%lu",
589			    virt_to_mfn(info->page));
590	if (ret)
591		goto error_xenbus;
592	ret = xenbus_printf(xbt, dev->nodename, "event-channel", "%u",
593			    evtchn);
594	if (ret)
595		goto error_xenbus;
596	ret = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
597			    XEN_IO_PROTO_ABI_NATIVE);
598	if (ret)
599		goto error_xenbus;
600	ret = xenbus_printf(xbt, dev->nodename, "feature-update", "1");
601	if (ret)
602		goto error_xenbus;
603	ret = xenbus_transaction_end(xbt, 0);
604	if (ret) {
605		if (ret == -EAGAIN)
606			goto again;
607		xenbus_dev_fatal(dev, ret, "completing transaction");
608		goto unbind_irq;
609	}
610
611	xenbus_switch_state(dev, XenbusStateInitialised);
612	info->irq = irq;
613	return 0;
614
615 error_xenbus:
616	xenbus_transaction_end(xbt, 1);
617	xenbus_dev_fatal(dev, ret, "writing xenstore");
618 unbind_irq:
619	unbind_from_irqhandler(irq, info);
620	return ret;
621}
622
623static void xenfb_disconnect_backend(struct xenfb_info *info)
624{
625	/* Prevent xenfb refresh */
626	info->update_wanted = 0;
627	if (info->irq >= 0)
628		unbind_from_irqhandler(info->irq, info);
629	info->irq = -1;
630}
631
632static void xenfb_backend_changed(struct xenbus_device *dev,
633				  enum xenbus_state backend_state)
634{
635	struct xenfb_info *info = dev_get_drvdata(&dev->dev);
636	int val;
637
638	switch (backend_state) {
639	case XenbusStateInitialising:
640	case XenbusStateInitialised:
641	case XenbusStateReconfiguring:
642	case XenbusStateReconfigured:
643	case XenbusStateUnknown:
644		break;
645
646	case XenbusStateInitWait:
647InitWait:
648		xenbus_switch_state(dev, XenbusStateConnected);
649		break;
650
651	case XenbusStateConnected:
652		/*
653		 * Work around xenbus race condition: If backend goes
654		 * through InitWait to Connected fast enough, we can
655		 * get Connected twice here.
656		 */
657		if (dev->state != XenbusStateConnected)
658			goto InitWait; /* no InitWait seen yet, fudge it */
659
660		if (xenbus_scanf(XBT_NIL, info->xbdev->otherend,
661				 "request-update", "%d", &val) < 0)
662			val = 0;
663		if (val)
664			info->update_wanted = 1;
665
666		if (xenbus_scanf(XBT_NIL, dev->otherend,
667				 "feature-resize", "%d", &val) < 0)
668			val = 0;
669		info->feature_resize = val;
670		break;
671
672	case XenbusStateClosed:
673		if (dev->state == XenbusStateClosed)
674			break;
675		/* Missed the backend's CLOSING state -- fallthrough */
676	case XenbusStateClosing:
677		xenbus_frontend_closed(dev);
678		break;
679	}
680}
681
682static const struct xenbus_device_id xenfb_ids[] = {
683	{ "vfb" },
684	{ "" }
685};
686
687static struct xenbus_driver xenfb_driver = {
688	.ids = xenfb_ids,
689	.probe = xenfb_probe,
690	.remove = xenfb_remove,
691	.resume = xenfb_resume,
692	.otherend_changed = xenfb_backend_changed,
693};
694
695static int __init xenfb_init(void)
696{
697	if (!xen_domain())
698		return -ENODEV;
699
700	/* Nothing to do if running in dom0. */
701	if (xen_initial_domain())
702		return -ENODEV;
703
704	if (!xen_has_pv_devices())
705		return -ENODEV;
706
707	return xenbus_register_frontend(&xenfb_driver);
708}
709
710static void __exit xenfb_cleanup(void)
711{
712	xenbus_unregister_driver(&xenfb_driver);
713}
714
715module_init(xenfb_init);
716module_exit(xenfb_cleanup);
717
718MODULE_DESCRIPTION("Xen virtual framebuffer device frontend");
719MODULE_LICENSE("GPL");
720MODULE_ALIAS("xen:vfb");
721