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, 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
 221fail:
 222        mutex_unlock(&evtchnl->u.req.req_io_lock);
 223fail_shbuf_alloc:
 224        dbuf_free(&front_info->dbuf_list, dbuf_cookie);
 225        return ret;
 226}
 227
 228static 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
 273int 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
 313int 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
 341int 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
 370void 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
 382static 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
 425fail_handle:
 426        xen_drm_front_dbuf_destroy(drm_info->front_info,
 427                                   xen_drm_front_dbuf_to_cookie(obj));
 428fail_backend:
 429        /* drop reference from allocate */
 430        drm_gem_object_put_unlocked(obj);
 431fail:
 432        DRM_ERROR("Failed to create dumb buffer: %d\n", ret);
 433        return ret;
 434}
 435
 436static 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
 453static 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
 473static 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
 487static const struct vm_operations_struct xen_drm_drv_vm_ops = {
 488        .open           = drm_gem_vm_open,
 489        .close          = drm_gem_vm_close,
 490};
 491
 492static 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
 514static 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
 559fail_register:
 560        drm_dev_unregister(drm_dev);
 561fail_modeset:
 562        drm_kms_helper_poll_fini(drm_dev);
 563        drm_mode_config_cleanup(drm_dev);
 564fail:
 565        kfree(drm_info);
 566        return ret;
 567}
 568
 569static 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
 604static 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
 623static 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
 629static 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
 640static 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
 714static 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
 740static 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
 777static const struct xenbus_device_id xen_driver_ids[] = {
 778        { XENDISPL_DRIVER_NAME },
 779        { "" }
 780};
 781
 782static 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
 789static 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
 808static 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
 814module_init(xen_drv_init);
 815module_exit(xen_drv_fini);
 816
 817MODULE_DESCRIPTION("Xen para-virtualized display device frontend");
 818MODULE_LICENSE("GPL");
 819MODULE_ALIAS("xen:" XENDISPL_DRIVER_NAME);
 820