drivers/gpu/drm/xen/xen_drm_front.c

   1 // SPDX-License-Identifier: GPL-2.0 OR MIT
   2
   3 /*
   4  *  Xen para-virtual DRM device
   5  *
   6  * Copyright (C) 2016-2018 EPAM Systems Inc.
   7  *
   8  * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
   9  */
  10
  11 #include <linux/delay.h>
  12 #include <linux/dma-mapping.h>
  13 #include <linux/module.h>
  14 #include <linux/of_device.h>
  15
  16 #include <drm/drm_atomic_helper.h>
  17 #include <drm/drm_drv.h>
  18 #include <drm/drm_ioctl.h>
  19 #include <drm/drm_probe_helper.h>
  20 #include <drm/drm_file.h>
  21 #include <drm/drm_gem.h>
  22
  23 #include <xen/platform_pci.h>
  24 #include <xen/xen.h>
  25 #include <xen/xenbus.h>
  26
  27 #include <xen/xen-front-pgdir-shbuf.h>
  28 #include <xen/interface/io/displif.h>
  29
  30 #include "xen_drm_front.h"
  31 #include "xen_drm_front_cfg.h"
  32 #include "xen_drm_front_evtchnl.h"
  33 #include "xen_drm_front_gem.h"
  34 #include "xen_drm_front_kms.h"
  35
  36 struct xen_drm_front_dbuf {
  37         struct list_head list;
  38         u64 dbuf_cookie;
  39         u64 fb_cookie;
  40
  41         struct xen_front_pgdir_shbuf shbuf;
  42 };
  43
  44 static void dbuf_add_to_list(struct xen_drm_front_info *front_info,
  45                              struct xen_drm_front_dbuf *dbuf, u64 dbuf_cookie)
  46 {
  47         dbuf->dbuf_cookie = dbuf_cookie;
  48         list_add(&dbuf->list, &front_info->dbuf_list);
  49 }
  50
  51 static struct xen_drm_front_dbuf *dbuf_get(struct list_head *dbuf_list,
  52                                            u64 dbuf_cookie)
  53 {
  54         struct xen_drm_front_dbuf *buf, *q;
  55
  56         list_for_each_entry_safe(buf, q, dbuf_list, list)
  57                 if (buf->dbuf_cookie == dbuf_cookie)
  58                         return buf;
  59
  60         return NULL;
  61 }
  62
  63 static void dbuf_free(struct list_head *dbuf_list, u64 dbuf_cookie)
  64 {
  65         struct xen_drm_front_dbuf *buf, *q;
  66
  67         list_for_each_entry_safe(buf, q, dbuf_list, list)
  68                 if (buf->dbuf_cookie == dbuf_cookie) {
  69                         list_del(&buf->list);
  70                         xen_front_pgdir_shbuf_unmap(&buf->shbuf);
  71                         xen_front_pgdir_shbuf_free(&buf->shbuf);
  72                         kfree(buf);
  73                         break;
  74                 }
  75 }
  76
  77 static void dbuf_free_all(struct list_head *dbuf_list)
  78 {
  79         struct xen_drm_front_dbuf *buf, *q;
  80
  81         list_for_each_entry_safe(buf, q, dbuf_list, list) {
  82                 list_del(&buf->list);
  83                 xen_front_pgdir_shbuf_unmap(&buf->shbuf);
  84                 xen_front_pgdir_shbuf_free(&buf->shbuf);
  85                 kfree(buf);
  86         }
  87 }
  88
  89 static struct xendispl_req *
  90 be_prepare_req(struct xen_drm_front_evtchnl *evtchnl, u8 operation)
  91 {
  92         struct xendispl_req *req;
  93
  94         req = RING_GET_REQUEST(&evtchnl->u.req.ring,
  95                                evtchnl->u.req.ring.req_prod_pvt);
  96         req->operation = operation;
  97         req->id = evtchnl->evt_next_id++;
  98         evtchnl->evt_id = req->id;
  99         return req;
 100 }
 101
 102 static int be_stream_do_io(struct xen_drm_front_evtchnl *evtchnl,
 103                            struct xendispl_req *req)
 104 {
 105         reinit_completion(&evtchnl->u.req.completion);
 106         if (unlikely(evtchnl->state != EVTCHNL_STATE_CONNECTED))
 107                 return -EIO;
 108
 109         xen_drm_front_evtchnl_flush(evtchnl);
 110         return 0;
 111 }
 112
 113 static int be_stream_wait_io(struct xen_drm_front_evtchnl *evtchnl)
 114 {
 115         if (wait_for_completion_timeout(&evtchnl->u.req.completion,
 116                         msecs_to_jiffies(XEN_DRM_FRONT_WAIT_BACK_MS)) <= 0)
 117                 return -ETIMEDOUT;
 118
 119         return evtchnl->u.req.resp_status;
 120 }
 121
 122 int xen_drm_front_mode_set(struct xen_drm_front_drm_pipeline *pipeline,
 123                            u32 x, u32 y, u32 width, u32 height,
 124                            u32 bpp, u64 fb_cookie)
 125 {
 126         struct xen_drm_front_evtchnl *evtchnl;
 127         struct xen_drm_front_info *front_info;
 128         struct xendispl_req *req;
 129         unsigned long flags;
 130         int ret;
 131
 132         front_info = pipeline->drm_info->front_info;
 133         evtchnl = &front_info->evt_pairs[pipeline->index].req;
 134         if (unlikely(!evtchnl))
 135                 return -EIO;
 136
 137         mutex_lock(&evtchnl->u.req.req_io_lock);
 138
 139         spin_lock_irqsave(&front_info->io_lock, flags);
 140         req = be_prepare_req(evtchnl, XENDISPL_OP_SET_CONFIG);
 141         req->op.set_config.x = x;
 142         req->op.set_config.y = y;
 143         req->op.set_config.width = width;
 144         req->op.set_config.height = height;
 145         req->op.set_config.bpp = bpp;
 146         req->op.set_config.fb_cookie = fb_cookie;
 147
 148         ret = be_stream_do_io(evtchnl, req);
 149         spin_unlock_irqrestore(&front_info->io_lock, flags);
 150
 151         if (ret == 0)
 152                 ret = be_stream_wait_io(evtchnl);
 153
 154         mutex_unlock(&evtchnl->u.req.req_io_lock);
 155         return ret;
 156 }
 157
 158 int xen_drm_front_dbuf_create(struct xen_drm_front_info *front_info,
 159                               u64 dbuf_cookie, u32 width, u32 height,
 160                               u32 bpp, u64 size, struct page **pages)
 161 {
 162         struct xen_drm_front_evtchnl *evtchnl;
 163         struct xen_drm_front_dbuf *dbuf;
 164         struct xendispl_req *req;
 165         struct xen_front_pgdir_shbuf_cfg buf_cfg;
 166         unsigned long flags;
 167         int ret;
 168
 169         evtchnl = &front_info->evt_pairs[GENERIC_OP_EVT_CHNL].req;
 170         if (unlikely(!evtchnl))
 171                 return -EIO;
 172
 173         dbuf = kzalloc(sizeof(*dbuf), GFP_KERNEL);
 174         if (!dbuf)
 175                 return -ENOMEM;
 176
 177         dbuf_add_to_list(front_info, dbuf, dbuf_cookie);
 178
 179         memset(&buf_cfg, 0, sizeof(buf_cfg));
 180         buf_cfg.xb_dev = front_info->xb_dev;
 181         buf_cfg.num_pages = DIV_ROUND_UP(size, PAGE_SIZE);
 182         buf_cfg.pages = pages;
 183         buf_cfg.pgdir = &dbuf->shbuf;
 184         buf_cfg.be_alloc = front_info->cfg.be_alloc;
 185
 186         ret = xen_front_pgdir_shbuf_alloc(&buf_cfg);
 187         if (ret < 0)
 188                 goto fail_shbuf_alloc;
 189
 190         mutex_lock(&evtchnl->u.req.req_io_lock);
 191
 192         spin_lock_irqsave(&front_info->io_lock, flags);
 193         req = be_prepare_req(evtchnl, XENDISPL_OP_DBUF_CREATE);
 194         req->op.dbuf_create.gref_directory =
 195                         xen_front_pgdir_shbuf_get_dir_start(&dbuf->shbuf);
 196         req->op.dbuf_create.buffer_sz = size;
 197         req->op.dbuf_create.dbuf_cookie = dbuf_cookie;
 198         req->op.dbuf_create.width = width;
 199         req->op.dbuf_create.height = height;
 200         req->op.dbuf_create.bpp = bpp;
 201         if (buf_cfg.be_alloc)
 202                 req->op.dbuf_create.flags |= XENDISPL_DBUF_FLG_REQ_ALLOC;
 203
 204         ret = be_stream_do_io(evtchnl, req);
 205         spin_unlock_irqrestore(&front_info->io_lock, flags);
 206
 207         if (ret < 0)
 208                 goto fail;
 209
 210         ret = be_stream_wait_io(evtchnl);
 211         if (ret < 0)
 212                 goto fail;
 213
 214         ret = xen_front_pgdir_shbuf_map(&dbuf->shbuf);
 215         if (ret < 0)
 216                 goto fail;
 217
 218         mutex_unlock(&evtchnl->u.req.req_io_lock);
 219         return 0;
 220
 221 fail:
 222         mutex_unlock(&evtchnl->u.req.req_io_lock);
 223 fail_shbuf_alloc:
 224         dbuf_free(&front_info->dbuf_list, dbuf_cookie);
 225         return ret;
 226 }
 227
 228 static int xen_drm_front_dbuf_destroy(struct xen_drm_front_info *front_info,
 229                                       u64 dbuf_cookie)
 230 {
 231         struct xen_drm_front_evtchnl *evtchnl;
 232         struct xendispl_req *req;
 233         unsigned long flags;
 234         bool be_alloc;
 235         int ret;
 236
 237         evtchnl = &front_info->evt_pairs[GENERIC_OP_EVT_CHNL].req;
 238         if (unlikely(!evtchnl))
 239                 return -EIO;
 240
 241         be_alloc = front_info->cfg.be_alloc;
 242
 243         /*
 244          * For the backend allocated buffer release references now, so backend
 245          * can free the buffer.
 246          */
 247         if (be_alloc)
 248                 dbuf_free(&front_info->dbuf_list, dbuf_cookie);
 249
 250         mutex_lock(&evtchnl->u.req.req_io_lock);
 251
 252         spin_lock_irqsave(&front_info->io_lock, flags);
 253         req = be_prepare_req(evtchnl, XENDISPL_OP_DBUF_DESTROY);
 254         req->op.dbuf_destroy.dbuf_cookie = dbuf_cookie;
 255
 256         ret = be_stream_do_io(evtchnl, req);
 257         spin_unlock_irqrestore(&front_info->io_lock, flags);
 258
 259         if (ret == 0)
 260                 ret = be_stream_wait_io(evtchnl);
 261
 262         /*
 263          * Do this regardless of communication status with the backend:
 264          * if we cannot remove remote resources remove what we can locally.
 265          */
 266         if (!be_alloc)
 267                 dbuf_free(&front_info->dbuf_list, dbuf_cookie);
 268
 269         mutex_unlock(&evtchnl->u.req.req_io_lock);
 270         return ret;
 271 }
 272
 273 int xen_drm_front_fb_attach(struct xen_drm_front_info *front_info,
 274                             u64 dbuf_cookie, u64 fb_cookie, u32 width,
 275                             u32 height, u32 pixel_format)
 276 {
 277         struct xen_drm_front_evtchnl *evtchnl;
 278         struct xen_drm_front_dbuf *buf;
 279         struct xendispl_req *req;
 280         unsigned long flags;
 281         int ret;
 282
 283         evtchnl = &front_info->evt_pairs[GENERIC_OP_EVT_CHNL].req;
 284         if (unlikely(!evtchnl))
 285                 return -EIO;
 286
 287         buf = dbuf_get(&front_info->dbuf_list, dbuf_cookie);
 288         if (!buf)
 289                 return -EINVAL;
 290
 291         buf->fb_cookie = fb_cookie;
 292
 293         mutex_lock(&evtchnl->u.req.req_io_lock);
 294
 295         spin_lock_irqsave(&front_info->io_lock, flags);
 296         req = be_prepare_req(evtchnl, XENDISPL_OP_FB_ATTACH);
 297         req->op.fb_attach.dbuf_cookie = dbuf_cookie;
 298         req->op.fb_attach.fb_cookie = fb_cookie;
 299         req->op.fb_attach.width = width;
 300         req->op.fb_attach.height = height;
 301         req->op.fb_attach.pixel_format = pixel_format;
 302
 303         ret = be_stream_do_io(evtchnl, req);
 304         spin_unlock_irqrestore(&front_info->io_lock, flags);
 305
 306         if (ret == 0)
 307                 ret = be_stream_wait_io(evtchnl);
 308
 309         mutex_unlock(&evtchnl->u.req.req_io_lock);
 310         return ret;
 311 }
 312
 313 int xen_drm_front_fb_detach(struct xen_drm_front_info *front_info,
 314                             u64 fb_cookie)
 315 {
 316         struct xen_drm_front_evtchnl *evtchnl;
 317         struct xendispl_req *req;
 318         unsigned long flags;
 319         int ret;
 320
 321         evtchnl = &front_info->evt_pairs[GENERIC_OP_EVT_CHNL].req;
 322         if (unlikely(!evtchnl))
 323                 return -EIO;
 324
 325         mutex_lock(&evtchnl->u.req.req_io_lock);
 326
 327         spin_lock_irqsave(&front_info->io_lock, flags);
 328         req = be_prepare_req(evtchnl, XENDISPL_OP_FB_DETACH);
 329         req->op.fb_detach.fb_cookie = fb_cookie;
 330
 331         ret = be_stream_do_io(evtchnl, req);
 332         spin_unlock_irqrestore(&front_info->io_lock, flags);
 333
 334         if (ret == 0)
 335                 ret = be_stream_wait_io(evtchnl);
 336
 337         mutex_unlock(&evtchnl->u.req.req_io_lock);
 338         return ret;
 339 }
 340
 341 int xen_drm_front_page_flip(struct xen_drm_front_info *front_info,
 342                             int conn_idx, u64 fb_cookie)
 343 {
 344         struct xen_drm_front_evtchnl *evtchnl;
 345         struct xendispl_req *req;
 346         unsigned long flags;
 347         int ret;
 348
 349         if (unlikely(conn_idx >= front_info->num_evt_pairs))
 350                 return -EINVAL;
 351
 352         evtchnl = &front_info->evt_pairs[conn_idx].req;
 353
 354         mutex_lock(&evtchnl->u.req.req_io_lock);
 355
 356         spin_lock_irqsave(&front_info->io_lock, flags);
 357         req = be_prepare_req(evtchnl, XENDISPL_OP_PG_FLIP);
 358         req->op.pg_flip.fb_cookie = fb_cookie;
 359
 360         ret = be_stream_do_io(evtchnl, req);
 361         spin_unlock_irqrestore(&front_info->io_lock, flags);
 362
 363         if (ret == 0)
 364                 ret = be_stream_wait_io(evtchnl);
 365
 366         mutex_unlock(&evtchnl->u.req.req_io_lock);
 367         return ret;
 368 }
 369
 370 void xen_drm_front_on_frame_done(struct xen_drm_front_info *front_info,
 371                                  int conn_idx, u64 fb_cookie)
 372 {
 373         struct xen_drm_front_drm_info *drm_info = front_info->drm_info;
 374
 375         if (unlikely(conn_idx >= front_info->cfg.num_connectors))
 376                 return;
 377
 378         xen_drm_front_kms_on_frame_done(&drm_info->pipeline[conn_idx],
 379                                         fb_cookie);
 380 }
 381
 382 static int xen_drm_drv_dumb_create(struct drm_file *filp,
 383                                    struct drm_device *dev,
 384                                    struct drm_mode_create_dumb *args)
 385 {
 386         struct xen_drm_front_drm_info *drm_info = dev->dev_private;
 387         struct drm_gem_object *obj;
 388         int ret;
 389
 390         /*
 391          * Dumb creation is a two stage process: first we create a fully
 392          * constructed GEM object which is communicated to the backend, and
 393          * only after that we can create GEM's handle. This is done so,
 394          * because of the possible races: once you create a handle it becomes
 395          * immediately visible to user-space, so the latter can try accessing
 396          * object without pages etc.
 397          * For details also see drm_gem_handle_create
 398          */
 399         args->pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
 400         args->size = args->pitch * args->height;
 401
 402         obj = xen_drm_front_gem_create(dev, args->size);
 403         if (IS_ERR_OR_NULL(obj)) {
 404                 ret = PTR_ERR(obj);
 405                 goto fail;
 406         }
 407
 408         ret = xen_drm_front_dbuf_create(drm_info->front_info,
 409                                         xen_drm_front_dbuf_to_cookie(obj),
 410                                         args->width, args->height, args->bpp,
 411                                         args->size,
 412                                         xen_drm_front_gem_get_pages(obj));
 413         if (ret)
 414                 goto fail_backend;
 415
 416         /* This is the tail of GEM object creation */
 417         ret = drm_gem_handle_create(filp, obj, &args->handle);
 418         if (ret)
 419                 goto fail_handle;
 420
 421         /* Drop reference from allocate - handle holds it now */
 422         drm_gem_object_put_unlocked(obj);
 423         return 0;
 424
 425 fail_handle:
 426         xen_drm_front_dbuf_destroy(drm_info->front_info,
 427                                    xen_drm_front_dbuf_to_cookie(obj));
 428 fail_backend:
 429         /* drop reference from allocate */
 430         drm_gem_object_put_unlocked(obj);
 431 fail:
 432         DRM_ERROR("Failed to create dumb buffer: %d\n", ret);
 433         return ret;
 434 }
 435
 436 static void xen_drm_drv_free_object_unlocked(struct drm_gem_object *obj)
 437 {
 438         struct xen_drm_front_drm_info *drm_info = obj->dev->dev_private;
 439         int idx;
 440
 441         if (drm_dev_enter(obj->dev, &idx)) {
 442                 xen_drm_front_dbuf_destroy(drm_info->front_info,
 443                                            xen_drm_front_dbuf_to_cookie(obj));
 444                 drm_dev_exit(idx);
 445         } else {
 446                 dbuf_free(&drm_info->front_info->dbuf_list,
 447                           xen_drm_front_dbuf_to_cookie(obj));
 448         }
 449
 450         xen_drm_front_gem_free_object_unlocked(obj);
 451 }
 452
 453 static void xen_drm_drv_release(struct drm_device *dev)
 454 {
 455         struct xen_drm_front_drm_info *drm_info = dev->dev_private;
 456         struct xen_drm_front_info *front_info = drm_info->front_info;
 457
 458         xen_drm_front_kms_fini(drm_info);
 459
 460         drm_atomic_helper_shutdown(dev);
 461         drm_mode_config_cleanup(dev);
 462
 463         drm_dev_fini(dev);
 464         kfree(dev);
 465
 466         if (front_info->cfg.be_alloc)
 467                 xenbus_switch_state(front_info->xb_dev,
 468                                     XenbusStateInitialising);
 469
 470         kfree(drm_info);
 471 }
 472
 473 static const struct file_operations xen_drm_dev_fops = {
 474         .owner          = THIS_MODULE,
 475         .open           = drm_open,
 476         .release        = drm_release,
 477         .unlocked_ioctl = drm_ioctl,
 478 #ifdef CONFIG_COMPAT
 479         .compat_ioctl   = drm_compat_ioctl,
 480 #endif
 481         .poll           = drm_poll,
 482         .read           = drm_read,
 483         .llseek         = no_llseek,
 484         .mmap           = xen_drm_front_gem_mmap,
 485 };
 486
 487 static const struct vm_operations_struct xen_drm_drv_vm_ops = {
 488         .open           = drm_gem_vm_open,
 489         .close          = drm_gem_vm_close,
 490 };
 491
 492 static struct drm_driver xen_drm_driver = {
 493         .driver_features           = DRIVER_GEM | DRIVER_MODESET | DRIVER_ATOMIC,
 494         .release                   = xen_drm_drv_release,
 495         .gem_vm_ops                = &xen_drm_drv_vm_ops,
 496         .gem_free_object_unlocked  = xen_drm_drv_free_object_unlocked,
 497         .prime_handle_to_fd        = drm_gem_prime_handle_to_fd,
 498         .prime_fd_to_handle        = drm_gem_prime_fd_to_handle,
 499         .gem_prime_import_sg_table = xen_drm_front_gem_import_sg_table,
 500         .gem_prime_get_sg_table    = xen_drm_front_gem_get_sg_table,
 501         .gem_prime_vmap            = xen_drm_front_gem_prime_vmap,
 502         .gem_prime_vunmap          = xen_drm_front_gem_prime_vunmap,
 503         .gem_prime_mmap            = xen_drm_front_gem_prime_mmap,
 504         .dumb_create               = xen_drm_drv_dumb_create,
 505         .fops                      = &xen_drm_dev_fops,
 506         .name                      = "xendrm-du",
 507         .desc                      = "Xen PV DRM Display Unit",
 508         .date                      = "20180221",
 509         .major                     = 1,
 510         .minor                     = 0,
 511
 512 };
 513
 514 static int xen_drm_drv_init(struct xen_drm_front_info *front_info)
 515 {
 516         struct device *dev = &front_info->xb_dev->dev;
 517         struct xen_drm_front_drm_info *drm_info;
 518         struct drm_device *drm_dev;
 519         int ret;
 520
 521         DRM_INFO("Creating %s\n", xen_drm_driver.desc);
 522
 523         drm_info = kzalloc(sizeof(*drm_info), GFP_KERNEL);
 524         if (!drm_info) {
 525                 ret = -ENOMEM;
 526                 goto fail;
 527         }
 528
 529         drm_info->front_info = front_info;
 530         front_info->drm_info = drm_info;
 531
 532         drm_dev = drm_dev_alloc(&xen_drm_driver, dev);
 533         if (IS_ERR(drm_dev)) {
 534                 ret = PTR_ERR(drm_dev);
 535                 goto fail;
 536         }
 537
 538         drm_info->drm_dev = drm_dev;
 539
 540         drm_dev->dev_private = drm_info;
 541
 542         ret = xen_drm_front_kms_init(drm_info);
 543         if (ret) {
 544                 DRM_ERROR("Failed to initialize DRM/KMS, ret %d\n", ret);
 545                 goto fail_modeset;
 546         }
 547
 548         ret = drm_dev_register(drm_dev, 0);
 549         if (ret)
 550                 goto fail_register;
 551
 552         DRM_INFO("Initialized %s %d.%d.%d %s on minor %d\n",
 553                  xen_drm_driver.name, xen_drm_driver.major,
 554                  xen_drm_driver.minor, xen_drm_driver.patchlevel,
 555                  xen_drm_driver.date, drm_dev->primary->index);
 556
 557         return 0;
 558
 559 fail_register:
 560         drm_dev_unregister(drm_dev);
 561 fail_modeset:
 562         drm_kms_helper_poll_fini(drm_dev);
 563         drm_mode_config_cleanup(drm_dev);
 564 fail:
 565         kfree(drm_info);
 566         return ret;
 567 }
 568
 569 static void xen_drm_drv_fini(struct xen_drm_front_info *front_info)
 570 {
 571         struct xen_drm_front_drm_info *drm_info = front_info->drm_info;
 572         struct drm_device *dev;
 573
 574         if (!drm_info)
 575                 return;
 576
 577         dev = drm_info->drm_dev;
 578         if (!dev)
 579                 return;
 580
 581         /* Nothing to do if device is already unplugged */
 582         if (drm_dev_is_unplugged(dev))
 583                 return;
 584
 585         drm_kms_helper_poll_fini(dev);
 586         drm_dev_unplug(dev);
 587         drm_dev_put(dev);
 588
 589         front_info->drm_info = NULL;
 590
 591         xen_drm_front_evtchnl_free_all(front_info);
 592         dbuf_free_all(&front_info->dbuf_list);
 593
 594         /*
 595          * If we are not using backend allocated buffers, then tell the
 596          * backend we are ready to (re)initialize. Otherwise, wait for
 597          * drm_driver.release.
 598          */
 599         if (!front_info->cfg.be_alloc)
 600                 xenbus_switch_state(front_info->xb_dev,
 601                                     XenbusStateInitialising);
 602 }
 603
 604 static int displback_initwait(struct xen_drm_front_info *front_info)
 605 {
 606         struct xen_drm_front_cfg *cfg = &front_info->cfg;
 607         int ret;
 608
 609         cfg->front_info = front_info;
 610         ret = xen_drm_front_cfg_card(front_info, cfg);
 611         if (ret < 0)
 612                 return ret;
 613
 614         DRM_INFO("Have %d connector(s)\n", cfg->num_connectors);
 615         /* Create event channels for all connectors and publish */
 616         ret = xen_drm_front_evtchnl_create_all(front_info);
 617         if (ret < 0)
 618                 return ret;
 619
 620         return xen_drm_front_evtchnl_publish_all(front_info);
 621 }
 622
 623 static int displback_connect(struct xen_drm_front_info *front_info)
 624 {
 625         xen_drm_front_evtchnl_set_state(front_info, EVTCHNL_STATE_CONNECTED);
 626         return xen_drm_drv_init(front_info);
 627 }
 628
 629 static void displback_disconnect(struct xen_drm_front_info *front_info)
 630 {
 631         if (!front_info->drm_info)
 632                 return;
 633
 634         /* Tell the backend to wait until we release the DRM driver. */
 635         xenbus_switch_state(front_info->xb_dev, XenbusStateReconfiguring);
 636
 637         xen_drm_drv_fini(front_info);
 638 }
 639
 640 static void displback_changed(struct xenbus_device *xb_dev,
 641                               enum xenbus_state backend_state)
 642 {
 643         struct xen_drm_front_info *front_info = dev_get_drvdata(&xb_dev->dev);
 644         int ret;
 645
 646         DRM_DEBUG("Backend state is %s, front is %s\n",
 647                   xenbus_strstate(backend_state),
 648                   xenbus_strstate(xb_dev->state));
 649
 650         switch (backend_state) {
 651         case XenbusStateReconfiguring:
 652                 /* fall through */
 653         case XenbusStateReconfigured:
 654                 /* fall through */
 655         case XenbusStateInitialised:
 656                 break;
 657
 658         case XenbusStateInitialising:
 659                 if (xb_dev->state == XenbusStateReconfiguring)
 660                         break;
 661
 662                 /* recovering after backend unexpected closure */
 663                 displback_disconnect(front_info);
 664                 break;
 665
 666         case XenbusStateInitWait:
 667                 if (xb_dev->state == XenbusStateReconfiguring)
 668                         break;
 669
 670                 /* recovering after backend unexpected closure */
 671                 displback_disconnect(front_info);
 672                 if (xb_dev->state != XenbusStateInitialising)
 673                         break;
 674
 675                 ret = displback_initwait(front_info);
 676                 if (ret < 0)
 677                         xenbus_dev_fatal(xb_dev, ret, "initializing frontend");
 678                 else
 679                         xenbus_switch_state(xb_dev, XenbusStateInitialised);
 680                 break;
 681
 682         case XenbusStateConnected:
 683                 if (xb_dev->state != XenbusStateInitialised)
 684                         break;
 685
 686                 ret = displback_connect(front_info);
 687                 if (ret < 0) {
 688                         displback_disconnect(front_info);
 689                         xenbus_dev_fatal(xb_dev, ret, "connecting backend");
 690                 } else {
 691                         xenbus_switch_state(xb_dev, XenbusStateConnected);
 692                 }
 693                 break;
 694
 695         case XenbusStateClosing:
 696                 /*
 697                  * in this state backend starts freeing resources,
 698                  * so let it go into closed state, so we can also
 699                  * remove ours
 700                  */
 701                 break;
 702
 703         case XenbusStateUnknown:
 704                 /* fall through */
 705         case XenbusStateClosed:
 706                 if (xb_dev->state == XenbusStateClosed)
 707                         break;
 708
 709                 displback_disconnect(front_info);
 710                 break;
 711         }
 712 }
 713
 714 static int xen_drv_probe(struct xenbus_device *xb_dev,
 715                          const struct xenbus_device_id *id)
 716 {
 717         struct xen_drm_front_info *front_info;
 718         struct device *dev = &xb_dev->dev;
 719         int ret;
 720
 721         ret = dma_coerce_mask_and_coherent(dev, DMA_BIT_MASK(64));
 722         if (ret < 0) {
 723                 DRM_ERROR("Cannot setup DMA mask, ret %d", ret);
 724                 return ret;
 725         }
 726
 727         front_info = devm_kzalloc(&xb_dev->dev,
 728                                   sizeof(*front_info), GFP_KERNEL);
 729         if (!front_info)
 730                 return -ENOMEM;
 731
 732         front_info->xb_dev = xb_dev;
 733         spin_lock_init(&front_info->io_lock);
 734         INIT_LIST_HEAD(&front_info->dbuf_list);
 735         dev_set_drvdata(&xb_dev->dev, front_info);
 736
 737         return xenbus_switch_state(xb_dev, XenbusStateInitialising);
 738 }
 739
 740 static int xen_drv_remove(struct xenbus_device *dev)
 741 {
 742         struct xen_drm_front_info *front_info = dev_get_drvdata(&dev->dev);
 743         int to = 100;
 744
 745         xenbus_switch_state(dev, XenbusStateClosing);
 746
 747         /*
 748          * On driver removal it is disconnected from XenBus,
 749          * so no backend state change events come via .otherend_changed
 750          * callback. This prevents us from exiting gracefully, e.g.
 751          * signaling the backend to free event channels, waiting for its
 752          * state to change to XenbusStateClosed and cleaning at our end.
 753          * Normally when front driver removed backend will finally go into
 754          * XenbusStateInitWait state.
 755          *
 756          * Workaround: read backend's state manually and wait with time-out.
 757          */
 758         while ((xenbus_read_unsigned(front_info->xb_dev->otherend, "state",
 759                                      XenbusStateUnknown) != XenbusStateInitWait) &&
 760                                      --to)
 761                 msleep(10);
 762
 763         if (!to) {
 764                 unsigned int state;
 765
 766                 state = xenbus_read_unsigned(front_info->xb_dev->otherend,
 767                                              "state", XenbusStateUnknown);
 768                 DRM_ERROR("Backend state is %s while removing driver\n",
 769                           xenbus_strstate(state));
 770         }
 771
 772         xen_drm_drv_fini(front_info);
 773         xenbus_frontend_closed(dev);
 774         return 0;
 775 }
 776
 777 static const struct xenbus_device_id xen_driver_ids[] = {
 778         { XENDISPL_DRIVER_NAME },
 779         { "" }
 780 };
 781
 782 static struct xenbus_driver xen_driver = {
 783         .ids = xen_driver_ids,
 784         .probe = xen_drv_probe,
 785         .remove = xen_drv_remove,
 786         .otherend_changed = displback_changed,
 787 };
 788
 789 static int __init xen_drv_init(void)
 790 {
 791         /* At the moment we only support case with XEN_PAGE_SIZE == PAGE_SIZE */
 792         if (XEN_PAGE_SIZE != PAGE_SIZE) {
 793                 DRM_ERROR(XENDISPL_DRIVER_NAME ": different kernel and Xen page sizes are not supported: XEN_PAGE_SIZE (%lu) != PAGE_SIZE (%lu)\n",
 794                           XEN_PAGE_SIZE, PAGE_SIZE);
 795                 return -ENODEV;
 796         }
 797
 798         if (!xen_domain())
 799                 return -ENODEV;
 800
 801         if (!xen_has_pv_devices())
 802                 return -ENODEV;
 803
 804         DRM_INFO("Registering XEN PV " XENDISPL_DRIVER_NAME "\n");
 805         return xenbus_register_frontend(&xen_driver);
 806 }
 807
 808 static void __exit xen_drv_fini(void)
 809 {
 810         DRM_INFO("Unregistering XEN PV " XENDISPL_DRIVER_NAME "\n");
 811         xenbus_unregister_driver(&xen_driver);
 812 }
 813
 814 module_init(xen_drv_init);
 815 module_exit(xen_drv_fini);
 816
 817 MODULE_DESCRIPTION("Xen para-virtualized display device frontend");
 818 MODULE_LICENSE("GPL");
 819 MODULE_ALIAS("xen:" XENDISPL_DRIVER_NAME);