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