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 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 const 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 .fb_mmap = fb_deferred_io_mmap, 340 }; 341 342 static irqreturn_t xenfb_event_handler(int rq, void *dev_id) 343 { 344 /* 345 * No in events recognized, simply ignore them all. 346 * If you need to recognize some, see xen-kbdfront's 347 * input_handler() for how to do that. 348 */ 349 struct xenfb_info *info = dev_id; 350 struct xenfb_page *page = info->page; 351 352 if (page->in_cons != page->in_prod) { 353 info->page->in_cons = info->page->in_prod; 354 notify_remote_via_irq(info->irq); 355 } 356 357 /* Flush dirty rectangle: */ 358 xenfb_refresh(info, INT_MAX, INT_MAX, -INT_MAX, -INT_MAX); 359 360 return IRQ_HANDLED; 361 } 362 363 static int xenfb_probe(struct xenbus_device *dev, 364 const struct xenbus_device_id *id) 365 { 366 struct xenfb_info *info; 367 struct fb_info *fb_info; 368 int fb_size; 369 int val; 370 int ret = 0; 371 372 info = kzalloc(sizeof(*info), GFP_KERNEL); 373 if (info == NULL) { 374 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure"); 375 return -ENOMEM; 376 } 377 378 /* Limit kernel param videoram amount to what is in xenstore */ 379 if (xenbus_scanf(XBT_NIL, dev->otherend, "videoram", "%d", &val) == 1) { 380 if (val < video[KPARAM_MEM]) 381 video[KPARAM_MEM] = val; 382 } 383 384 video[KPARAM_WIDTH] = xenbus_read_unsigned(dev->otherend, "width", 385 video[KPARAM_WIDTH]); 386 video[KPARAM_HEIGHT] = xenbus_read_unsigned(dev->otherend, "height", 387 video[KPARAM_HEIGHT]); 388 389 /* If requested res does not fit in available memory, use default */ 390 fb_size = video[KPARAM_MEM] * 1024 * 1024; 391 if (video[KPARAM_WIDTH] * video[KPARAM_HEIGHT] * XENFB_DEPTH / 8 392 > fb_size) { 393 pr_warn("display parameters %d,%d,%d invalid, use defaults\n", 394 video[KPARAM_MEM], video[KPARAM_WIDTH], 395 video[KPARAM_HEIGHT]); 396 video[KPARAM_WIDTH] = XENFB_WIDTH; 397 video[KPARAM_HEIGHT] = XENFB_HEIGHT; 398 fb_size = XENFB_DEFAULT_FB_LEN; 399 } 400 401 dev_set_drvdata(&dev->dev, info); 402 info->xbdev = dev; 403 info->irq = -1; 404 info->x1 = info->y1 = INT_MAX; 405 spin_lock_init(&info->dirty_lock); 406 spin_lock_init(&info->resize_lock); 407 408 info->fb = vzalloc(fb_size); 409 if (info->fb == NULL) 410 goto error_nomem; 411 412 info->nr_pages = (fb_size + PAGE_SIZE - 1) >> PAGE_SHIFT; 413 414 info->gfns = vmalloc(array_size(sizeof(unsigned long), info->nr_pages)); 415 if (!info->gfns) 416 goto error_nomem; 417 418 /* set up shared page */ 419 info->page = (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO); 420 if (!info->page) 421 goto error_nomem; 422 423 /* abusing framebuffer_alloc() to allocate pseudo_palette */ 424 fb_info = framebuffer_alloc(sizeof(u32) * 256, NULL); 425 if (fb_info == NULL) 426 goto error_nomem; 427 428 /* complete the abuse: */ 429 fb_info->pseudo_palette = fb_info->par; 430 fb_info->par = info; 431 432 fb_info->screen_base = info->fb; 433 434 fb_info->fbops = &xenfb_fb_ops; 435 fb_info->var.xres_virtual = fb_info->var.xres = video[KPARAM_WIDTH]; 436 fb_info->var.yres_virtual = fb_info->var.yres = video[KPARAM_HEIGHT]; 437 fb_info->var.bits_per_pixel = XENFB_DEPTH; 438 439 fb_info->var.red = (struct fb_bitfield){16, 8, 0}; 440 fb_info->var.green = (struct fb_bitfield){8, 8, 0}; 441 fb_info->var.blue = (struct fb_bitfield){0, 8, 0}; 442 443 fb_info->var.activate = FB_ACTIVATE_NOW; 444 fb_info->var.height = -1; 445 fb_info->var.width = -1; 446 fb_info->var.vmode = FB_VMODE_NONINTERLACED; 447 448 fb_info->fix.visual = FB_VISUAL_TRUECOLOR; 449 fb_info->fix.line_length = fb_info->var.xres * XENFB_DEPTH / 8; 450 fb_info->fix.smem_start = 0; 451 fb_info->fix.smem_len = fb_size; 452 strcpy(fb_info->fix.id, "xen"); 453 fb_info->fix.type = FB_TYPE_PACKED_PIXELS; 454 fb_info->fix.accel = FB_ACCEL_NONE; 455 456 fb_info->flags = FBINFO_FLAG_DEFAULT | FBINFO_VIRTFB; 457 458 ret = fb_alloc_cmap(&fb_info->cmap, 256, 0); 459 if (ret < 0) { 460 framebuffer_release(fb_info); 461 xenbus_dev_fatal(dev, ret, "fb_alloc_cmap"); 462 goto error; 463 } 464 465 fb_info->fbdefio = &xenfb_defio; 466 fb_deferred_io_init(fb_info); 467 468 xenfb_init_shared_page(info, fb_info); 469 470 ret = xenfb_connect_backend(dev, info); 471 if (ret < 0) { 472 xenbus_dev_fatal(dev, ret, "xenfb_connect_backend"); 473 goto error_fb; 474 } 475 476 ret = register_framebuffer(fb_info); 477 if (ret) { 478 xenbus_dev_fatal(dev, ret, "register_framebuffer"); 479 goto error_fb; 480 } 481 info->fb_info = fb_info; 482 483 xenfb_make_preferred_console(); 484 return 0; 485 486 error_fb: 487 fb_deferred_io_cleanup(fb_info); 488 fb_dealloc_cmap(&fb_info->cmap); 489 framebuffer_release(fb_info); 490 error_nomem: 491 if (!ret) { 492 ret = -ENOMEM; 493 xenbus_dev_fatal(dev, ret, "allocating device memory"); 494 } 495 error: 496 xenfb_remove(dev); 497 return ret; 498 } 499 500 static void xenfb_make_preferred_console(void) 501 { 502 struct console *c; 503 504 if (console_set_on_cmdline) 505 return; 506 507 console_list_lock(); 508 for_each_console(c) { 509 if (!strcmp(c->name, "tty") && c->index == 0) 510 break; 511 } 512 if (c) 513 console_force_preferred_locked(c); 514 console_list_unlock(); 515 } 516 517 static int xenfb_resume(struct xenbus_device *dev) 518 { 519 struct xenfb_info *info = dev_get_drvdata(&dev->dev); 520 521 xenfb_disconnect_backend(info); 522 xenfb_init_shared_page(info, info->fb_info); 523 return xenfb_connect_backend(dev, info); 524 } 525 526 static void xenfb_remove(struct xenbus_device *dev) 527 { 528 struct xenfb_info *info = dev_get_drvdata(&dev->dev); 529 530 xenfb_disconnect_backend(info); 531 if (info->fb_info) { 532 fb_deferred_io_cleanup(info->fb_info); 533 unregister_framebuffer(info->fb_info); 534 fb_dealloc_cmap(&info->fb_info->cmap); 535 framebuffer_release(info->fb_info); 536 } 537 free_page((unsigned long)info->page); 538 vfree(info->gfns); 539 vfree(info->fb); 540 kfree(info); 541 } 542 543 static unsigned long vmalloc_to_gfn(void *address) 544 { 545 return xen_page_to_gfn(vmalloc_to_page(address)); 546 } 547 548 static void xenfb_init_shared_page(struct xenfb_info *info, 549 struct fb_info *fb_info) 550 { 551 int i; 552 int epd = PAGE_SIZE / sizeof(info->gfns[0]); 553 554 for (i = 0; i < info->nr_pages; i++) 555 info->gfns[i] = vmalloc_to_gfn(info->fb + i * PAGE_SIZE); 556 557 for (i = 0; i * epd < info->nr_pages; i++) 558 info->page->pd[i] = vmalloc_to_gfn(&info->gfns[i * epd]); 559 560 info->page->width = fb_info->var.xres; 561 info->page->height = fb_info->var.yres; 562 info->page->depth = fb_info->var.bits_per_pixel; 563 info->page->line_length = fb_info->fix.line_length; 564 info->page->mem_length = fb_info->fix.smem_len; 565 info->page->in_cons = info->page->in_prod = 0; 566 info->page->out_cons = info->page->out_prod = 0; 567 } 568 569 static int xenfb_connect_backend(struct xenbus_device *dev, 570 struct xenfb_info *info) 571 { 572 int ret, evtchn, irq; 573 struct xenbus_transaction xbt; 574 575 ret = xenbus_alloc_evtchn(dev, &evtchn); 576 if (ret) 577 return ret; 578 irq = bind_evtchn_to_irqhandler(evtchn, xenfb_event_handler, 579 0, dev->devicetype, info); 580 if (irq < 0) { 581 xenbus_free_evtchn(dev, evtchn); 582 xenbus_dev_fatal(dev, ret, "bind_evtchn_to_irqhandler"); 583 return irq; 584 } 585 again: 586 ret = xenbus_transaction_start(&xbt); 587 if (ret) { 588 xenbus_dev_fatal(dev, ret, "starting transaction"); 589 goto unbind_irq; 590 } 591 ret = xenbus_printf(xbt, dev->nodename, "page-ref", "%lu", 592 virt_to_gfn(info->page)); 593 if (ret) 594 goto error_xenbus; 595 ret = xenbus_printf(xbt, dev->nodename, "event-channel", "%u", 596 evtchn); 597 if (ret) 598 goto error_xenbus; 599 ret = xenbus_printf(xbt, dev->nodename, "protocol", "%s", 600 XEN_IO_PROTO_ABI_NATIVE); 601 if (ret) 602 goto error_xenbus; 603 ret = xenbus_printf(xbt, dev->nodename, "feature-update", "1"); 604 if (ret) 605 goto error_xenbus; 606 ret = xenbus_transaction_end(xbt, 0); 607 if (ret) { 608 if (ret == -EAGAIN) 609 goto again; 610 xenbus_dev_fatal(dev, ret, "completing transaction"); 611 goto unbind_irq; 612 } 613 614 xenbus_switch_state(dev, XenbusStateInitialised); 615 info->irq = irq; 616 return 0; 617 618 error_xenbus: 619 xenbus_transaction_end(xbt, 1); 620 xenbus_dev_fatal(dev, ret, "writing xenstore"); 621 unbind_irq: 622 unbind_from_irqhandler(irq, info); 623 return ret; 624 } 625 626 static void xenfb_disconnect_backend(struct xenfb_info *info) 627 { 628 /* Prevent xenfb refresh */ 629 info->update_wanted = 0; 630 if (info->irq >= 0) 631 unbind_from_irqhandler(info->irq, info); 632 info->irq = -1; 633 } 634 635 static void xenfb_backend_changed(struct xenbus_device *dev, 636 enum xenbus_state backend_state) 637 { 638 struct xenfb_info *info = dev_get_drvdata(&dev->dev); 639 640 switch (backend_state) { 641 case XenbusStateInitialising: 642 case XenbusStateInitialised: 643 case XenbusStateReconfiguring: 644 case XenbusStateReconfigured: 645 case XenbusStateUnknown: 646 break; 647 648 case XenbusStateInitWait: 649 xenbus_switch_state(dev, XenbusStateConnected); 650 break; 651 652 case XenbusStateConnected: 653 /* 654 * Work around xenbus race condition: If backend goes 655 * through InitWait to Connected fast enough, we can 656 * get Connected twice here. 657 */ 658 if (dev->state != XenbusStateConnected) 659 /* no InitWait seen yet, fudge it */ 660 xenbus_switch_state(dev, XenbusStateConnected); 661 662 if (xenbus_read_unsigned(info->xbdev->otherend, 663 "request-update", 0)) 664 info->update_wanted = 1; 665 666 info->feature_resize = xenbus_read_unsigned(dev->otherend, 667 "feature-resize", 0); 668 break; 669 670 case XenbusStateClosed: 671 if (dev->state == XenbusStateClosed) 672 break; 673 fallthrough; /* Missed the backend's CLOSING state */ 674 case XenbusStateClosing: 675 xenbus_frontend_closed(dev); 676 break; 677 } 678 } 679 680 static const struct xenbus_device_id xenfb_ids[] = { 681 { "vfb" }, 682 { "" } 683 }; 684 685 static struct xenbus_driver xenfb_driver = { 686 .ids = xenfb_ids, 687 .probe = xenfb_probe, 688 .remove = xenfb_remove, 689 .resume = xenfb_resume, 690 .otherend_changed = xenfb_backend_changed, 691 .not_essential = true, 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