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 #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           *gfns;
  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->gfns = vmalloc(sizeof(unsigned long) * info->nr_pages);
 406         if (!info->gfns)
 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->gfns);
 534         vfree(info->fb);
 535         kfree(info);
 536
 537         return 0;
 538 }
 539
 540 static unsigned long vmalloc_to_gfn(void *address)
 541 {
 542         return xen_page_to_gfn(vmalloc_to_page(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->gfns[0]);
 550
 551         for (i = 0; i < info->nr_pages; i++)
 552                 info->gfns[i] = vmalloc_to_gfn(info->fb + i * PAGE_SIZE);
 553
 554         for (i = 0; i * epd < info->nr_pages; i++)
 555                 info->page->pd[i] = vmalloc_to_gfn(&info->gfns[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_gfn(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 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
 695 static 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
 710 static void __exit xenfb_cleanup(void)
 711 {
 712         xenbus_unregister_driver(&xenfb_driver);
 713 }
 714
 715 module_init(xenfb_init);
 716 module_exit(xenfb_cleanup);
 717
 718 MODULE_DESCRIPTION("Xen virtual framebuffer device frontend");
 719 MODULE_LICENSE("GPL");
 720 MODULE_ALIAS("xen:vfb");