drivers/gpu/drm/msm/msm_gem.c

   1 /*
   2  * Copyright (C) 2013 Red Hat
   3  * Author: Rob Clark <robdclark@gmail.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 as published by
   7  * the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  12  * more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along with
  15  * this program.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 #include <linux/spinlock.h>
  19 #include <linux/shmem_fs.h>
  20 #include <linux/dma-buf.h>
  21
  22 #include "msm_drv.h"
  23 #include "msm_gem.h"
  24 #include "msm_gpu.h"
  25 #include "msm_mmu.h"
  26
  27 static dma_addr_t physaddr(struct drm_gem_object *obj)
  28 {
  29         struct msm_gem_object *msm_obj = to_msm_bo(obj);
  30         struct msm_drm_private *priv = obj->dev->dev_private;
  31         return (((dma_addr_t)msm_obj->vram_node->start) << PAGE_SHIFT) +
  32                         priv->vram.paddr;
  33 }
  34
  35 /* allocate pages from VRAM carveout, used when no IOMMU: */
  36 static struct page **get_pages_vram(struct drm_gem_object *obj,
  37                 int npages)
  38 {
  39         struct msm_gem_object *msm_obj = to_msm_bo(obj);
  40         struct msm_drm_private *priv = obj->dev->dev_private;
  41         dma_addr_t paddr;
  42         struct page **p;
  43         int ret, i;
  44
  45         p = drm_malloc_ab(npages, sizeof(struct page *));
  46         if (!p)
  47                 return ERR_PTR(-ENOMEM);
  48
  49         ret = drm_mm_insert_node(&priv->vram.mm, msm_obj->vram_node,
  50                         npages, 0, DRM_MM_SEARCH_DEFAULT);
  51         if (ret) {
  52                 drm_free_large(p);
  53                 return ERR_PTR(ret);
  54         }
  55
  56         paddr = physaddr(obj);
  57         for (i = 0; i < npages; i++) {
  58                 p[i] = phys_to_page(paddr);
  59                 paddr += PAGE_SIZE;
  60         }
  61
  62         return p;
  63 }
  64
  65 /* called with dev->struct_mutex held */
  66 static struct page **get_pages(struct drm_gem_object *obj)
  67 {
  68         struct msm_gem_object *msm_obj = to_msm_bo(obj);
  69
  70         if (!msm_obj->pages) {
  71                 struct drm_device *dev = obj->dev;
  72                 struct page **p;
  73                 int npages = obj->size >> PAGE_SHIFT;
  74
  75                 if (iommu_present(&platform_bus_type))
  76                         p = drm_gem_get_pages(obj);
  77                 else
  78                         p = get_pages_vram(obj, npages);
  79
  80                 if (IS_ERR(p)) {
  81                         dev_err(dev->dev, "could not get pages: %ld\n",
  82                                         PTR_ERR(p));
  83                         return p;
  84                 }
  85
  86                 msm_obj->sgt = drm_prime_pages_to_sg(p, npages);
  87                 if (IS_ERR(msm_obj->sgt)) {
  88                         dev_err(dev->dev, "failed to allocate sgt\n");
  89                         return ERR_CAST(msm_obj->sgt);
  90                 }
  91
  92                 msm_obj->pages = p;
  93
  94                 /* For non-cached buffers, ensure the new pages are clean
  95                  * because display controller, GPU, etc. are not coherent:
  96                  */
  97                 if (msm_obj->flags & (MSM_BO_WC|MSM_BO_UNCACHED))
  98                         dma_map_sg(dev->dev, msm_obj->sgt->sgl,
  99                                         msm_obj->sgt->nents, DMA_BIDIRECTIONAL);
 100         }
 101
 102         return msm_obj->pages;
 103 }
 104
 105 static void put_pages(struct drm_gem_object *obj)
 106 {
 107         struct msm_gem_object *msm_obj = to_msm_bo(obj);
 108
 109         if (msm_obj->pages) {
 110                 /* For non-cached buffers, ensure the new pages are clean
 111                  * because display controller, GPU, etc. are not coherent:
 112                  */
 113                 if (msm_obj->flags & (MSM_BO_WC|MSM_BO_UNCACHED))
 114                         dma_unmap_sg(obj->dev->dev, msm_obj->sgt->sgl,
 115                                         msm_obj->sgt->nents, DMA_BIDIRECTIONAL);
 116                 sg_free_table(msm_obj->sgt);
 117                 kfree(msm_obj->sgt);
 118
 119                 if (iommu_present(&platform_bus_type))
 120                         drm_gem_put_pages(obj, msm_obj->pages, true, false);
 121                 else {
 122                         drm_mm_remove_node(msm_obj->vram_node);
 123                         drm_free_large(msm_obj->pages);
 124                 }
 125
 126                 msm_obj->pages = NULL;
 127         }
 128 }
 129
 130 struct page **msm_gem_get_pages(struct drm_gem_object *obj)
 131 {
 132         struct drm_device *dev = obj->dev;
 133         struct page **p;
 134         mutex_lock(&dev->struct_mutex);
 135         p = get_pages(obj);
 136         mutex_unlock(&dev->struct_mutex);
 137         return p;
 138 }
 139
 140 void msm_gem_put_pages(struct drm_gem_object *obj)
 141 {
 142         /* when we start tracking the pin count, then do something here */
 143 }
 144
 145 int msm_gem_mmap_obj(struct drm_gem_object *obj,
 146                 struct vm_area_struct *vma)
 147 {
 148         struct msm_gem_object *msm_obj = to_msm_bo(obj);
 149
 150         vma->vm_flags &= ~VM_PFNMAP;
 151         vma->vm_flags |= VM_MIXEDMAP;
 152
 153         if (msm_obj->flags & MSM_BO_WC) {
 154                 vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
 155         } else if (msm_obj->flags & MSM_BO_UNCACHED) {
 156                 vma->vm_page_prot = pgprot_noncached(vm_get_page_prot(vma->vm_flags));
 157         } else {
 158                 /*
 159                  * Shunt off cached objs to shmem file so they have their own
 160                  * address_space (so unmap_mapping_range does what we want,
 161                  * in particular in the case of mmap'd dmabufs)
 162                  */
 163                 fput(vma->vm_file);
 164                 get_file(obj->filp);
 165                 vma->vm_pgoff = 0;
 166                 vma->vm_file  = obj->filp;
 167
 168                 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 169         }
 170
 171         return 0;
 172 }
 173
 174 int msm_gem_mmap(struct file *filp, struct vm_area_struct *vma)
 175 {
 176         int ret;
 177
 178         ret = drm_gem_mmap(filp, vma);
 179         if (ret) {
 180                 DBG("mmap failed: %d", ret);
 181                 return ret;
 182         }
 183
 184         return msm_gem_mmap_obj(vma->vm_private_data, vma);
 185 }
 186
 187 int msm_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 188 {
 189         struct drm_gem_object *obj = vma->vm_private_data;
 190         struct drm_device *dev = obj->dev;
 191         struct page **pages;
 192         unsigned long pfn;
 193         pgoff_t pgoff;
 194         int ret;
 195
 196         /* Make sure we don't parallel update on a fault, nor move or remove
 197          * something from beneath our feet
 198          */
 199         ret = mutex_lock_interruptible(&dev->struct_mutex);
 200         if (ret)
 201                 goto out;
 202
 203         /* make sure we have pages attached now */
 204         pages = get_pages(obj);
 205         if (IS_ERR(pages)) {
 206                 ret = PTR_ERR(pages);
 207                 goto out_unlock;
 208         }
 209
 210         /* We don't use vmf->pgoff since that has the fake offset: */
 211         pgoff = ((unsigned long)vmf->virtual_address -
 212                         vma->vm_start) >> PAGE_SHIFT;
 213
 214         pfn = page_to_pfn(pages[pgoff]);
 215
 216         VERB("Inserting %p pfn %lx, pa %lx", vmf->virtual_address,
 217                         pfn, pfn << PAGE_SHIFT);
 218
 219         ret = vm_insert_mixed(vma, (unsigned long)vmf->virtual_address, pfn);
 220
 221 out_unlock:
 222         mutex_unlock(&dev->struct_mutex);
 223 out:
 224         switch (ret) {
 225         case -EAGAIN:
 226         case 0:
 227         case -ERESTARTSYS:
 228         case -EINTR:
 229         case -EBUSY:
 230                 /*
 231                  * EBUSY is ok: this just means that another thread
 232                  * already did the job.
 233                  */
 234                 return VM_FAULT_NOPAGE;
 235         case -ENOMEM:
 236                 return VM_FAULT_OOM;
 237         default:
 238                 return VM_FAULT_SIGBUS;
 239         }
 240 }
 241
 242 /** get mmap offset */
 243 static uint64_t mmap_offset(struct drm_gem_object *obj)
 244 {
 245         struct drm_device *dev = obj->dev;
 246         int ret;
 247
 248         WARN_ON(!mutex_is_locked(&dev->struct_mutex));
 249
 250         /* Make it mmapable */
 251         ret = drm_gem_create_mmap_offset(obj);
 252
 253         if (ret) {
 254                 dev_err(dev->dev, "could not allocate mmap offset\n");
 255                 return 0;
 256         }
 257
 258         return drm_vma_node_offset_addr(&obj->vma_node);
 259 }
 260
 261 uint64_t msm_gem_mmap_offset(struct drm_gem_object *obj)
 262 {
 263         uint64_t offset;
 264         mutex_lock(&obj->dev->struct_mutex);
 265         offset = mmap_offset(obj);
 266         mutex_unlock(&obj->dev->struct_mutex);
 267         return offset;
 268 }
 269
 270 /* should be called under struct_mutex.. although it can be called
 271  * from atomic context without struct_mutex to acquire an extra
 272  * iova ref if you know one is already held.
 273  *
 274  * That means when I do eventually need to add support for unpinning
 275  * the refcnt counter needs to be atomic_t.
 276  */
 277 int msm_gem_get_iova_locked(struct drm_gem_object *obj, int id,
 278                 uint32_t *iova)
 279 {
 280         struct msm_gem_object *msm_obj = to_msm_bo(obj);
 281         int ret = 0;
 282
 283         if (!msm_obj->domain[id].iova) {
 284                 struct msm_drm_private *priv = obj->dev->dev_private;
 285                 struct page **pages = get_pages(obj);
 286
 287                 if (IS_ERR(pages))
 288                         return PTR_ERR(pages);
 289
 290                 if (iommu_present(&platform_bus_type)) {
 291                         struct msm_mmu *mmu = priv->mmus[id];
 292                         uint32_t offset;
 293
 294                         if (WARN_ON(!mmu))
 295                                 return -EINVAL;
 296
 297                         offset = (uint32_t)mmap_offset(obj);
 298                         ret = mmu->funcs->map(mmu, offset, msm_obj->sgt,
 299                                         obj->size, IOMMU_READ | IOMMU_WRITE);
 300                         msm_obj->domain[id].iova = offset;
 301                 } else {
 302                         msm_obj->domain[id].iova = physaddr(obj);
 303                 }
 304         }
 305
 306         if (!ret)
 307                 *iova = msm_obj->domain[id].iova;
 308
 309         return ret;
 310 }
 311
 312 /* get iova, taking a reference.  Should have a matching put */
 313 int msm_gem_get_iova(struct drm_gem_object *obj, int id, uint32_t *iova)
 314 {
 315         struct msm_gem_object *msm_obj = to_msm_bo(obj);
 316         int ret;
 317
 318         /* this is safe right now because we don't unmap until the
 319          * bo is deleted:
 320          */
 321         if (msm_obj->domain[id].iova) {
 322                 *iova = msm_obj->domain[id].iova;
 323                 return 0;
 324         }
 325
 326         mutex_lock(&obj->dev->struct_mutex);
 327         ret = msm_gem_get_iova_locked(obj, id, iova);
 328         mutex_unlock(&obj->dev->struct_mutex);
 329         return ret;
 330 }
 331
 332 /* get iova without taking a reference, used in places where you have
 333  * already done a 'msm_gem_get_iova()'.
 334  */
 335 uint32_t msm_gem_iova(struct drm_gem_object *obj, int id)
 336 {
 337         struct msm_gem_object *msm_obj = to_msm_bo(obj);
 338         WARN_ON(!msm_obj->domain[id].iova);
 339         return msm_obj->domain[id].iova;
 340 }
 341
 342 void msm_gem_put_iova(struct drm_gem_object *obj, int id)
 343 {
 344         // XXX TODO ..
 345         // NOTE: probably don't need a _locked() version.. we wouldn't
 346         // normally unmap here, but instead just mark that it could be
 347         // unmapped (if the iova refcnt drops to zero), but then later
 348         // if another _get_iova_locked() fails we can start unmapping
 349         // things that are no longer needed..
 350 }
 351
 352 int msm_gem_dumb_create(struct drm_file *file, struct drm_device *dev,
 353                 struct drm_mode_create_dumb *args)
 354 {
 355         args->pitch = align_pitch(args->width, args->bpp);
 356         args->size  = PAGE_ALIGN(args->pitch * args->height);
 357         return msm_gem_new_handle(dev, file, args->size,
 358                         MSM_BO_SCANOUT | MSM_BO_WC, &args->handle);
 359 }
 360
 361 int msm_gem_dumb_map_offset(struct drm_file *file, struct drm_device *dev,
 362                 uint32_t handle, uint64_t *offset)
 363 {
 364         struct drm_gem_object *obj;
 365         int ret = 0;
 366
 367         /* GEM does all our handle to object mapping */
 368         obj = drm_gem_object_lookup(dev, file, handle);
 369         if (obj == NULL) {
 370                 ret = -ENOENT;
 371                 goto fail;
 372         }
 373
 374         *offset = msm_gem_mmap_offset(obj);
 375
 376         drm_gem_object_unreference_unlocked(obj);
 377
 378 fail:
 379         return ret;
 380 }
 381
 382 void *msm_gem_vaddr_locked(struct drm_gem_object *obj)
 383 {
 384         struct msm_gem_object *msm_obj = to_msm_bo(obj);
 385         WARN_ON(!mutex_is_locked(&obj->dev->struct_mutex));
 386         if (!msm_obj->vaddr) {
 387                 struct page **pages = get_pages(obj);
 388                 if (IS_ERR(pages))
 389                         return ERR_CAST(pages);
 390                 msm_obj->vaddr = vmap(pages, obj->size >> PAGE_SHIFT,
 391                                 VM_MAP, pgprot_writecombine(PAGE_KERNEL));
 392         }
 393         return msm_obj->vaddr;
 394 }
 395
 396 void *msm_gem_vaddr(struct drm_gem_object *obj)
 397 {
 398         void *ret;
 399         mutex_lock(&obj->dev->struct_mutex);
 400         ret = msm_gem_vaddr_locked(obj);
 401         mutex_unlock(&obj->dev->struct_mutex);
 402         return ret;
 403 }
 404
 405 /* setup callback for when bo is no longer busy..
 406  * TODO probably want to differentiate read vs write..
 407  */
 408 int msm_gem_queue_inactive_cb(struct drm_gem_object *obj,
 409                 struct msm_fence_cb *cb)
 410 {
 411         struct msm_gem_object *msm_obj = to_msm_bo(obj);
 412         uint32_t fence = msm_gem_fence(msm_obj,
 413                         MSM_PREP_READ | MSM_PREP_WRITE);
 414         return msm_queue_fence_cb(obj->dev, cb, fence);
 415 }
 416
 417 void msm_gem_move_to_active(struct drm_gem_object *obj,
 418                 struct msm_gpu *gpu, bool write, uint32_t fence)
 419 {
 420         struct msm_gem_object *msm_obj = to_msm_bo(obj);
 421         msm_obj->gpu = gpu;
 422         if (write)
 423                 msm_obj->write_fence = fence;
 424         else
 425                 msm_obj->read_fence = fence;
 426         list_del_init(&msm_obj->mm_list);
 427         list_add_tail(&msm_obj->mm_list, &gpu->active_list);
 428 }
 429
 430 void msm_gem_move_to_inactive(struct drm_gem_object *obj)
 431 {
 432         struct drm_device *dev = obj->dev;
 433         struct msm_drm_private *priv = dev->dev_private;
 434         struct msm_gem_object *msm_obj = to_msm_bo(obj);
 435
 436         WARN_ON(!mutex_is_locked(&dev->struct_mutex));
 437
 438         msm_obj->gpu = NULL;
 439         msm_obj->read_fence = 0;
 440         msm_obj->write_fence = 0;
 441         list_del_init(&msm_obj->mm_list);
 442         list_add_tail(&msm_obj->mm_list, &priv->inactive_list);
 443 }
 444
 445 int msm_gem_cpu_prep(struct drm_gem_object *obj, uint32_t op,
 446                 struct timespec *timeout)
 447 {
 448         struct drm_device *dev = obj->dev;
 449         struct msm_gem_object *msm_obj = to_msm_bo(obj);
 450         int ret = 0;
 451
 452         if (is_active(msm_obj)) {
 453                 uint32_t fence = msm_gem_fence(msm_obj, op);
 454
 455                 if (op & MSM_PREP_NOSYNC)
 456                         timeout = NULL;
 457
 458                 ret = msm_wait_fence_interruptable(dev, fence, timeout);
 459         }
 460
 461         /* TODO cache maintenance */
 462
 463         return ret;
 464 }
 465
 466 int msm_gem_cpu_fini(struct drm_gem_object *obj)
 467 {
 468         /* TODO cache maintenance */
 469         return 0;
 470 }
 471
 472 #ifdef CONFIG_DEBUG_FS
 473 void msm_gem_describe(struct drm_gem_object *obj, struct seq_file *m)
 474 {
 475         struct drm_device *dev = obj->dev;
 476         struct msm_gem_object *msm_obj = to_msm_bo(obj);
 477         uint64_t off = drm_vma_node_start(&obj->vma_node);
 478
 479         WARN_ON(!mutex_is_locked(&dev->struct_mutex));
 480         seq_printf(m, "%08x: %c(r=%u,w=%u) %2d (%2d) %08llx %p %d\n",
 481                         msm_obj->flags, is_active(msm_obj) ? 'A' : 'I',
 482                         msm_obj->read_fence, msm_obj->write_fence,
 483                         obj->name, obj->refcount.refcount.counter,
 484                         off, msm_obj->vaddr, obj->size);
 485 }
 486
 487 void msm_gem_describe_objects(struct list_head *list, struct seq_file *m)
 488 {
 489         struct msm_gem_object *msm_obj;
 490         int count = 0;
 491         size_t size = 0;
 492
 493         list_for_each_entry(msm_obj, list, mm_list) {
 494                 struct drm_gem_object *obj = &msm_obj->base;
 495                 seq_printf(m, "   ");
 496                 msm_gem_describe(obj, m);
 497                 count++;
 498                 size += obj->size;
 499         }
 500
 501         seq_printf(m, "Total %d objects, %zu bytes\n", count, size);
 502 }
 503 #endif
 504
 505 void msm_gem_free_object(struct drm_gem_object *obj)
 506 {
 507         struct drm_device *dev = obj->dev;
 508         struct msm_drm_private *priv = obj->dev->dev_private;
 509         struct msm_gem_object *msm_obj = to_msm_bo(obj);
 510         int id;
 511
 512         WARN_ON(!mutex_is_locked(&dev->struct_mutex));
 513
 514         /* object should not be on active list: */
 515         WARN_ON(is_active(msm_obj));
 516
 517         list_del(&msm_obj->mm_list);
 518
 519         for (id = 0; id < ARRAY_SIZE(msm_obj->domain); id++) {
 520                 struct msm_mmu *mmu = priv->mmus[id];
 521                 if (mmu && msm_obj->domain[id].iova) {
 522                         uint32_t offset = msm_obj->domain[id].iova;
 523                         mmu->funcs->unmap(mmu, offset, msm_obj->sgt, obj->size);
 524                 }
 525         }
 526
 527         if (obj->import_attach) {
 528                 if (msm_obj->vaddr)
 529                         dma_buf_vunmap(obj->import_attach->dmabuf, msm_obj->vaddr);
 530
 531                 /* Don't drop the pages for imported dmabuf, as they are not
 532                  * ours, just free the array we allocated:
 533                  */
 534                 if (msm_obj->pages)
 535                         drm_free_large(msm_obj->pages);
 536
 537         } else {
 538                 vunmap(msm_obj->vaddr);
 539                 put_pages(obj);
 540         }
 541
 542         if (msm_obj->resv == &msm_obj->_resv)
 543                 reservation_object_fini(msm_obj->resv);
 544
 545         drm_gem_object_release(obj);
 546
 547         kfree(msm_obj);
 548 }
 549
 550 /* convenience method to construct a GEM buffer object, and userspace handle */
 551 int msm_gem_new_handle(struct drm_device *dev, struct drm_file *file,
 552                 uint32_t size, uint32_t flags, uint32_t *handle)
 553 {
 554         struct drm_gem_object *obj;
 555         int ret;
 556
 557         ret = mutex_lock_interruptible(&dev->struct_mutex);
 558         if (ret)
 559                 return ret;
 560
 561         obj = msm_gem_new(dev, size, flags);
 562
 563         mutex_unlock(&dev->struct_mutex);
 564
 565         if (IS_ERR(obj))
 566                 return PTR_ERR(obj);
 567
 568         ret = drm_gem_handle_create(file, obj, handle);
 569
 570         /* drop reference from allocate - handle holds it now */
 571         drm_gem_object_unreference_unlocked(obj);
 572
 573         return ret;
 574 }
 575
 576 static int msm_gem_new_impl(struct drm_device *dev,
 577                 uint32_t size, uint32_t flags,
 578                 struct drm_gem_object **obj)
 579 {
 580         struct msm_drm_private *priv = dev->dev_private;
 581         struct msm_gem_object *msm_obj;
 582         unsigned sz;
 583
 584         switch (flags & MSM_BO_CACHE_MASK) {
 585         case MSM_BO_UNCACHED:
 586         case MSM_BO_CACHED:
 587         case MSM_BO_WC:
 588                 break;
 589         default:
 590                 dev_err(dev->dev, "invalid cache flag: %x\n",
 591                                 (flags & MSM_BO_CACHE_MASK));
 592                 return -EINVAL;
 593         }
 594
 595         sz = sizeof(*msm_obj);
 596         if (!iommu_present(&platform_bus_type))
 597                 sz += sizeof(struct drm_mm_node);
 598
 599         msm_obj = kzalloc(sz, GFP_KERNEL);
 600         if (!msm_obj)
 601                 return -ENOMEM;
 602
 603         if (!iommu_present(&platform_bus_type))
 604                 msm_obj->vram_node = (void *)&msm_obj[1];
 605
 606         msm_obj->flags = flags;
 607
 608         msm_obj->resv = &msm_obj->_resv;
 609         reservation_object_init(msm_obj->resv);
 610
 611         INIT_LIST_HEAD(&msm_obj->submit_entry);
 612         list_add_tail(&msm_obj->mm_list, &priv->inactive_list);
 613
 614         *obj = &msm_obj->base;
 615
 616         return 0;
 617 }
 618
 619 struct drm_gem_object *msm_gem_new(struct drm_device *dev,
 620                 uint32_t size, uint32_t flags)
 621 {
 622         struct drm_gem_object *obj = NULL;
 623         int ret;
 624
 625         WARN_ON(!mutex_is_locked(&dev->struct_mutex));
 626
 627         size = PAGE_ALIGN(size);
 628
 629         ret = msm_gem_new_impl(dev, size, flags, &obj);
 630         if (ret)
 631                 goto fail;
 632
 633         if (iommu_present(&platform_bus_type)) {
 634                 ret = drm_gem_object_init(dev, obj, size);
 635                 if (ret)
 636                         goto fail;
 637         } else {
 638                 drm_gem_private_object_init(dev, obj, size);
 639         }
 640
 641         return obj;
 642
 643 fail:
 644         if (obj)
 645                 drm_gem_object_unreference(obj);
 646
 647         return ERR_PTR(ret);
 648 }
 649
 650 struct drm_gem_object *msm_gem_import(struct drm_device *dev,
 651                 uint32_t size, struct sg_table *sgt)
 652 {
 653         struct msm_gem_object *msm_obj;
 654         struct drm_gem_object *obj;
 655         int ret, npages;
 656
 657         /* if we don't have IOMMU, don't bother pretending we can import: */
 658         if (!iommu_present(&platform_bus_type)) {
 659                 dev_err(dev->dev, "cannot import without IOMMU\n");
 660                 return ERR_PTR(-EINVAL);
 661         }
 662
 663         size = PAGE_ALIGN(size);
 664
 665         ret = msm_gem_new_impl(dev, size, MSM_BO_WC, &obj);
 666         if (ret)
 667                 goto fail;
 668
 669         drm_gem_private_object_init(dev, obj, size);
 670
 671         npages = size / PAGE_SIZE;
 672
 673         msm_obj = to_msm_bo(obj);
 674         msm_obj->sgt = sgt;
 675         msm_obj->pages = drm_malloc_ab(npages, sizeof(struct page *));
 676         if (!msm_obj->pages) {
 677                 ret = -ENOMEM;
 678                 goto fail;
 679         }
 680
 681         ret = drm_prime_sg_to_page_addr_arrays(sgt, msm_obj->pages, NULL, npages);
 682         if (ret)
 683                 goto fail;
 684
 685         return obj;
 686
 687 fail:
 688         if (obj)
 689                 drm_gem_object_unreference_unlocked(obj);
 690
 691         return ERR_PTR(ret);
 692 }