drivers/video/fbdev/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 #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
  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
  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
 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
 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
 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
 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
 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
 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
 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
 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
 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
 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
 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
 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
 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
 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
 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
 522 static unsigned long vmalloc_to_gfn(void *address)
 523 {
 524         return xen_page_to_gfn(vmalloc_to_page(address));
 525 }
 526
 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
 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
 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
 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
 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
 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");