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