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 
40 struct 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 
61 enum { KPARAM_MEM, KPARAM_WIDTH, KPARAM_HEIGHT, KPARAM_CNT };
62 static int video[KPARAM_CNT] = { 2, XENFB_WIDTH, XENFB_HEIGHT };
63 module_param_array(video, int, NULL, 0);
64 MODULE_PARM_DESC(video,
65 	"Video memory size in MB, width, height in pixels (default 2,800,600)");
66 
67 static void xenfb_make_preferred_console(void);
68 static int xenfb_remove(struct xenbus_device *);
69 static void xenfb_init_shared_page(struct xenfb_info *, struct fb_info *);
70 static int xenfb_connect_backend(struct xenbus_device *, struct xenfb_info *);
71 static void xenfb_disconnect_backend(struct xenfb_info *);
72 
73 static 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 
88 static 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 
104 static 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 
115 static 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 
124 static 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 
138 static 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 
182 static 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 
207 static struct fb_deferred_io xenfb_defio = {
208 	.delay		= HZ / 20,
209 	.deferred_io	= xenfb_deferred_io,
210 };
211 
212 static 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 
243 static 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 
251 static 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 
259 static 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 
267 static 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 
278 static int
279 xenfb_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 
310 static 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 
329 static 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 
341 static 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 
362 static 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 
477 error_fb:
478 	fb_deferred_io_cleanup(fb_info);
479 	fb_dealloc_cmap(&fb_info->cmap);
480 	framebuffer_release(fb_info);
481 error_nomem:
482 	if (!ret) {
483 		ret = -ENOMEM;
484 		xenbus_dev_fatal(dev, ret, "allocating device memory");
485 	}
486 error:
487 	xenfb_remove(dev);
488 	return ret;
489 }
490 
491 static 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 
512 static 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 
521 static 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 
540 static unsigned long vmalloc_to_mfn(void *address)
541 {
542 	return pfn_to_mfn(vmalloc_to_pfn(address));
543 }
544 
545 static 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 
566 static 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 
623 static 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 
632 static 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:
647 InitWait:
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 
682 static const struct xenbus_device_id xenfb_ids[] = {
683 	{ "vfb" },
684 	{ "" }
685 };
686 
687 static DEFINE_XENBUS_DRIVER(xenfb, ,
688 	.probe = xenfb_probe,
689 	.remove = xenfb_remove,
690 	.resume = xenfb_resume,
691 	.otherend_changed = xenfb_backend_changed,
692 );
693 
694 static int __init xenfb_init(void)
695 {
696 	if (!xen_domain())
697 		return -ENODEV;
698 
699 	/* Nothing to do if running in dom0. */
700 	if (xen_initial_domain())
701 		return -ENODEV;
702 
703 	if (!xen_has_pv_devices())
704 		return -ENODEV;
705 
706 	return xenbus_register_frontend(&xenfb_driver);
707 }
708 
709 static void __exit xenfb_cleanup(void)
710 {
711 	xenbus_unregister_driver(&xenfb_driver);
712 }
713 
714 module_init(xenfb_init);
715 module_exit(xenfb_cleanup);
716 
717 MODULE_DESCRIPTION("Xen virtual framebuffer device frontend");
718 MODULE_LICENSE("GPL");
719 MODULE_ALIAS("xen:vfb");
720