text: /*
   * drivers/staging/omapdrm/omap_gem.c
   *
   * Copyright (C) 2011 Texas Instruments
   * Author: Rob Clark <rob.clark@linaro.org>
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 as published by
   * the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
   * more details.
   *
   * You should have received a copy of the GNU General Public License along with
   * this program.  If not, see <http://www.gnu.org/licenses/>.
   */
  
  
  #include <linux/spinlock.h>
  #include <linux/shmem_fs.h>
  
  #include "omap_drv.h"
  #include "omap_dmm_tiler.h"
  
  /* remove these once drm core helpers are merged */
  struct page ** _drm_gem_get_pages(struct drm_gem_object *obj, gfp_t gfpmask);
  void _drm_gem_put_pages(struct drm_gem_object *obj, struct page **pages,
  		bool dirty, bool accessed);
  int _drm_gem_create_mmap_offset_size(struct drm_gem_object *obj, size_t size);
  
  /*
   * GEM buffer object implementation.
   */
  
  #define to_omap_bo(x) container_of(x, struct omap_gem_object, base)
  
  /* note: we use upper 8 bits of flags for driver-internal flags: */
  #define OMAP_BO_DMA			0x01000000	/* actually is physically contiguous */
  #define OMAP_BO_EXT_SYNC	0x02000000	/* externally allocated sync object */
  #define OMAP_BO_EXT_MEM		0x04000000	/* externally allocated memory */
  
  
  struct omap_gem_object {
  	struct drm_gem_object base;
  
  	struct list_head mm_list;
  
  	uint32_t flags;
  
  	/** width/height for tiled formats (rounded up to slot boundaries) */
  	uint16_t width, height;
  
  	/** roll applied when mapping to DMM */
  	uint32_t roll;
  
  	/**
  	 * If buffer is allocated physically contiguous, the OMAP_BO_DMA flag
  	 * is set and the paddr is valid.  Also if the buffer is remapped in
  	 * TILER and paddr_cnt > 0, then paddr is valid.  But if you are using
  	 * the physical address and OMAP_BO_DMA is not set, then you should
  	 * be going thru omap_gem_{get,put}_paddr() to ensure the mapping is
  	 * not removed from under your feet.
  	 *
  	 * Note that OMAP_BO_SCANOUT is a hint from userspace that DMA capable
  	 * buffer is requested, but doesn't mean that it is.  Use the
  	 * OMAP_BO_DMA flag to determine if the buffer has a DMA capable
  	 * physical address.
  	 */
  	dma_addr_t paddr;
  
  	/**
  	 * # of users of paddr
  	 */
  	uint32_t paddr_cnt;
  
  	/**
  	 * tiler block used when buffer is remapped in DMM/TILER.
  	 */
  	struct tiler_block *block;
  
  	/**
  	 * Array of backing pages, if allocated.  Note that pages are never
  	 * allocated for buffers originally allocated from contiguous memory
  	 */
  	struct page **pages;
  
  	/** addresses corresponding to pages in above array */
  	dma_addr_t *addrs;
  
  	/**
  	 * Virtual address, if mapped.
  	 */
  	void *vaddr;
  
  	/**
  	 * sync-object allocated on demand (if needed)
  	 *
  	 * Per-buffer sync-object for tracking pending and completed hw/dma
  	 * read and write operations.  The layout in memory is dictated by
  	 * the SGX firmware, which uses this information to stall the command
  	 * stream if a surface is not ready yet.
  	 *
  	 * Note that when buffer is used by SGX, the sync-object needs to be
  	 * allocated from a special heap of sync-objects.  This way many sync
  	 * objects can be packed in a page, and not waste GPU virtual address
  	 * space.  Because of this we have to have a omap_gem_set_sync_object()
  	 * API to allow replacement of the syncobj after it has (potentially)
  	 * already been allocated.  A bit ugly but I haven't thought of a
  	 * better alternative.
  	 */
  	struct {
  		uint32_t write_pending;
  		uint32_t write_complete;
  		uint32_t read_pending;
  		uint32_t read_complete;
  	} *sync;
  };
  
  static int get_pages(struct drm_gem_object *obj, struct page ***pages);
  static uint64_t mmap_offset(struct drm_gem_object *obj);
  
  /* To deal with userspace mmap'ings of 2d tiled buffers, which (a) are
   * not necessarily pinned in TILER all the time, and (b) when they are
   * they are not necessarily page aligned, we reserve one or more small
   * regions in each of the 2d containers to use as a user-GART where we
   * can create a second page-aligned mapping of parts of the buffer
   * being accessed from userspace.
   *
   * Note that we could optimize slightly when we know that multiple
   * tiler containers are backed by the same PAT.. but I'll leave that
   * for later..
   */
  #define NUM_USERGART_ENTRIES 2
  struct usergart_entry {
  	struct tiler_block *block;	/* the reserved tiler block */
  	dma_addr_t paddr;
  	struct drm_gem_object *obj;	/* the current pinned obj */
  	pgoff_t obj_pgoff;		/* page offset of obj currently
  					   mapped in */
  };
  static struct {
  	struct usergart_entry entry[NUM_USERGART_ENTRIES];
  	int height;				/* height in rows */
  	int height_shift;		/* ilog2(height in rows) */
  	int slot_shift;			/* ilog2(width per slot) */
  	int stride_pfn;			/* stride in pages */
  	int last;				/* index of last used entry */
  } *usergart;
  
  static void evict_entry(struct drm_gem_object *obj,
  		enum tiler_fmt fmt, struct usergart_entry *entry)
  {
  	if (obj->dev->dev_mapping) {
  		struct omap_gem_object *omap_obj = to_omap_bo(obj);
  		int n = usergart[fmt].height;
  		size_t size = PAGE_SIZE * n;
  		loff_t off = mmap_offset(obj) +
  				(entry->obj_pgoff << PAGE_SHIFT);
  		const int m = 1 + ((omap_obj->width << fmt) / PAGE_SIZE);
  		if (m > 1) {
  			int i;
  			/* if stride > than PAGE_SIZE then sparse mapping: */
  			for (i = n; i > 0; i--) {
  				unmap_mapping_range(obj->dev->dev_mapping,
  						off, PAGE_SIZE, 1);
  				off += PAGE_SIZE * m;
  			}
  		} else {
  			unmap_mapping_range(obj->dev->dev_mapping, off, size, 1);
  		}
  	}
  
  	entry->obj = NULL;
  }
  
  /* Evict a buffer from usergart, if it is mapped there */
  static void evict(struct drm_gem_object *obj)
  {
  	struct omap_gem_object *omap_obj = to_omap_bo(obj);
  
  	if (omap_obj->flags & OMAP_BO_TILED) {
  		enum tiler_fmt fmt = gem2fmt(omap_obj->flags);
  		int i;
  
  		if (!usergart)
  			return;
  
  		for (i = 0; i < NUM_USERGART_ENTRIES; i++) {
  			struct usergart_entry *entry = &usergart[fmt].entry[i];
  			if (entry->obj == obj)
  				evict_entry(obj, fmt, entry);
  		}
  	}
  }
  
  /* GEM objects can either be allocated from contiguous memory (in which
   * case obj->filp==NULL), or w/ shmem backing (obj->filp!=NULL).  But non
   * contiguous buffers can be remapped in TILER/DMM if they need to be
   * contiguous... but we don't do this all the time to reduce pressure
   * on TILER/DMM space when we know at allocation time that the buffer
   * will need to be scanned out.
   */
  static inline bool is_shmem(struct drm_gem_object *obj)
  {
  	return obj->filp != NULL;
  }
  
  /**
   * shmem buffers that are mapped cached can simulate coherency via using
   * page faulting to keep track of dirty pages
   */
  static inline bool is_cached_coherent(struct drm_gem_object *obj)
  {
  	struct omap_gem_object *omap_obj = to_omap_bo(obj);
  	return is_shmem(obj) &&
  		((omap_obj->flags & OMAP_BO_CACHE_MASK) == OMAP_BO_CACHED);
  }
  
  static DEFINE_SPINLOCK(sync_lock);
  
  /** ensure backing pages are allocated */
  static int omap_gem_attach_pages(struct drm_gem_object *obj)
  {
  	struct drm_device *dev = obj->dev;
  	struct omap_gem_object *omap_obj = to_omap_bo(obj);
  	struct page **pages;
  	int npages = obj->size >> PAGE_SHIFT;
  	int i, ret;
  	dma_addr_t *addrs;
  
  	WARN_ON(omap_obj->pages);
  
  	/* TODO: __GFP_DMA32 .. but somehow GFP_HIGHMEM is coming from the
  	 * mapping_gfp_mask(mapping) which conflicts w/ GFP_DMA32.. probably
  	 * we actually want CMA memory for it all anyways..
  	 */
  	pages = _drm_gem_get_pages(obj, GFP_KERNEL);
  	if (IS_ERR(pages)) {
  		dev_err(obj->dev->dev, "could not get pages: %ld\n", PTR_ERR(pages));
  		return PTR_ERR(pages);
  	}
  
  	/* for non-cached buffers, ensure the new pages are clean because
  	 * DSS, GPU, etc. are not cache coherent:
  	 */
  	if (omap_obj->flags & (OMAP_BO_WC|OMAP_BO_UNCACHED)) {
  		addrs = kmalloc(npages * sizeof(*addrs), GFP_KERNEL);
  		if (!addrs) {
  			ret = -ENOMEM;
  			goto free_pages;
  		}
  
  		for (i = 0; i < npages; i++) {
  			addrs[i] = dma_map_page(dev->dev, pages[i],
  					0, PAGE_SIZE, DMA_BIDIRECTIONAL);
  		}
  	} else {
  		addrs = kzalloc(npages * sizeof(*addrs), GFP_KERNEL);
  		if (!addrs) {
  			ret = -ENOMEM;
  			goto free_pages;
  		}
  	}
  
  	omap_obj->addrs = addrs;
  	omap_obj->pages = pages;
  
  	return 0;
  
  free_pages:
  	_drm_gem_put_pages(obj, pages, true, false);
  
  	return ret;
  }
  
  /** release backing pages */
  static void omap_gem_detach_pages(struct drm_gem_object *obj)
  {
  	struct omap_gem_object *omap_obj = to_omap_bo(obj);
  
  	/* for non-cached buffers, ensure the new pages are clean because
  	 * DSS, GPU, etc. are not cache coherent:
  	 */
  	if (omap_obj->flags & (OMAP_BO_WC|OMAP_BO_UNCACHED)) {
  		int i, npages = obj->size >> PAGE_SHIFT;
  		for (i = 0; i < npages; i++) {
  			dma_unmap_page(obj->dev->dev, omap_obj->addrs[i],
  					PAGE_SIZE, DMA_BIDIRECTIONAL);
  		}
  	}
  
  	kfree(omap_obj->addrs);
  	omap_obj->addrs = NULL;
  
  	_drm_gem_put_pages(obj, omap_obj->pages, true, false);
  	omap_obj->pages = NULL;
  }
  
  /* get buffer flags */
  uint32_t omap_gem_flags(struct drm_gem_object *obj)
  {
  	return to_omap_bo(obj)->flags;
  }
  
  /** get mmap offset */
  static uint64_t mmap_offset(struct drm_gem_object *obj)
  {
  	struct drm_device *dev = obj->dev;
  
  	WARN_ON(!mutex_is_locked(&dev->struct_mutex));
  
  	if (!obj->map_list.map) {
  		/* Make it mmapable */
  		size_t size = omap_gem_mmap_size(obj);
  		int ret = _drm_gem_create_mmap_offset_size(obj, size);
  
  		if (ret) {
  			dev_err(dev->dev, "could not allocate mmap offset\n");
  			return 0;
  		}
  	}
  
  	return (uint64_t)obj->map_list.hash.key << PAGE_SHIFT;
  }
  
  uint64_t omap_gem_mmap_offset(struct drm_gem_object *obj)
  {
  	uint64_t offset;
  	mutex_lock(&obj->dev->struct_mutex);
  	offset = mmap_offset(obj);
  	mutex_unlock(&obj->dev->struct_mutex);
  	return offset;
  }
  
  /** get mmap size */
  size_t omap_gem_mmap_size(struct drm_gem_object *obj)
  {
  	struct omap_gem_object *omap_obj = to_omap_bo(obj);
  	size_t size = obj->size;
  
  	if (omap_obj->flags & OMAP_BO_TILED) {
  		/* for tiled buffers, the virtual size has stride rounded up
  		 * to 4kb.. (to hide the fact that row n+1 might start 16kb or
  		 * 32kb later!).  But we don't back the entire buffer with
  		 * pages, only the valid picture part.. so need to adjust for
  		 * this in the size used to mmap and generate mmap offset
  		 */
  		size = tiler_vsize(gem2fmt(omap_obj->flags),
  				omap_obj->width, omap_obj->height);
  	}
  
  	return size;
  }
  
  /* get tiled size, returns -EINVAL if not tiled buffer */
  int omap_gem_tiled_size(struct drm_gem_object *obj, uint16_t *w, uint16_t *h)
  {
  	struct omap_gem_object *omap_obj = to_omap_bo(obj);
  	if (omap_obj->flags & OMAP_BO_TILED) {
  		*w = omap_obj->width;
  		*h = omap_obj->height;
  		return 0;
  	}
  	return -EINVAL;
  }
  
  /* Normal handling for the case of faulting in non-tiled buffers */
  static int fault_1d(struct drm_gem_object *obj,
  		struct vm_area_struct *vma, struct vm_fault *vmf)
  {
  	struct omap_gem_object *omap_obj = to_omap_bo(obj);
  	unsigned long pfn;
  	pgoff_t pgoff;
  
  	/* We don't use vmf->pgoff since that has the fake offset: */
  	pgoff = ((unsigned long)vmf->virtual_address -
  			vma->vm_start) >> PAGE_SHIFT;
  
  	if (omap_obj->pages) {
  		omap_gem_cpu_sync(obj, pgoff);
  		pfn = page_to_pfn(omap_obj->pages[pgoff]);
  	} else {
  		BUG_ON(!(omap_obj->flags & OMAP_BO_DMA));
  		pfn = (omap_obj->paddr >> PAGE_SHIFT) + pgoff;
  	}
  
  	VERB("Inserting %p pfn %lx, pa %lx", vmf->virtual_address,
  			pfn, pfn << PAGE_SHIFT);
  
  	return vm_insert_mixed(vma, (unsigned long)vmf->virtual_address, pfn);
  }
  
  /* Special handling for the case of faulting in 2d tiled buffers */
  static int fault_2d(struct drm_gem_object *obj,
  		struct vm_area_struct *vma, struct vm_fault *vmf)
  {
  	struct omap_gem_object *omap_obj = to_omap_bo(obj);
  	struct usergart_entry *entry;
  	enum tiler_fmt fmt = gem2fmt(omap_obj->flags);
  	struct page *pages[64];  /* XXX is this too much to have on stack? */
  	unsigned long pfn;
  	pgoff_t pgoff, base_pgoff;
  	void __user *vaddr;
  	int i, ret, slots;
  
  	/*
  	 * Note the height of the slot is also equal to the number of pages
  	 * that need to be mapped in to fill 4kb wide CPU page.  If the slot
  	 * height is 64, then 64 pages fill a 4kb wide by 64 row region.
  	 */
  	const int n = usergart[fmt].height;
  	const int n_shift = usergart[fmt].height_shift;
  
  	/*
  	 * If buffer width in bytes > PAGE_SIZE then the virtual stride is
  	 * rounded up to next multiple of PAGE_SIZE.. this need to be taken
  	 * into account in some of the math, so figure out virtual stride
  	 * in pages
  	 */
  	const int m = 1 + ((omap_obj->width << fmt) / PAGE_SIZE);
  
  	/* We don't use vmf->pgoff since that has the fake offset: */
  	pgoff = ((unsigned long)vmf->virtual_address -
  			vma->vm_start) >> PAGE_SHIFT;
  
  	/*
  	 * Actual address we start mapping at is rounded down to previous slot
  	 * boundary in the y direction:
  	 */
  	base_pgoff = round_down(pgoff, m << n_shift);
  
  	/* figure out buffer width in slots */
  	slots = omap_obj->width >> usergart[fmt].slot_shift;
  
  	vaddr = vmf->virtual_address - ((pgoff - base_pgoff) << PAGE_SHIFT);
  
  	entry = &usergart[fmt].entry[usergart[fmt].last];
  
  	/* evict previous buffer using this usergart entry, if any: */
  	if (entry->obj)
  		evict_entry(entry->obj, fmt, entry);
  
  	entry->obj = obj;
  	entry->obj_pgoff = base_pgoff;
  
  	/* now convert base_pgoff to phys offset from virt offset: */
  	base_pgoff = (base_pgoff >> n_shift) * slots;
  
  	/* for wider-than 4k.. figure out which part of the slot-row we want: */
  	if (m > 1) {
  		int off = pgoff % m;
  		entry->obj_pgoff += off;
  		base_pgoff /= m;
  		slots = min(slots - (off << n_shift), n);
  		base_pgoff += off << n_shift;
  		vaddr += off << PAGE_SHIFT;
  	}
  
  	/*
  	 * Map in pages. Beyond the valid pixel part of the buffer, we set
  	 * pages[i] to NULL to get a dummy page mapped in.. if someone
  	 * reads/writes it they will get random/undefined content, but at
  	 * least it won't be corrupting whatever other random page used to
  	 * be mapped in, or other undefined behavior.
  	 */
  	memcpy(pages, &omap_obj->pages[base_pgoff],
  			sizeof(struct page *) * slots);
  	memset(pages + slots, 0,
  			sizeof(struct page *) * (n - slots));
  
  	ret = tiler_pin(entry->block, pages, ARRAY_SIZE(pages), 0, true);
  	if (ret) {
  		dev_err(obj->dev->dev, "failed to pin: %d\n", ret);
  		return ret;
  	}
  
  	pfn = entry->paddr >> PAGE_SHIFT;
  
  	VERB("Inserting %p pfn %lx, pa %lx", vmf->virtual_address,
  			pfn, pfn << PAGE_SHIFT);
  
  	for (i = n; i > 0; i--) {
  		vm_insert_mixed(vma, (unsigned long)vaddr, pfn);
  		pfn += usergart[fmt].stride_pfn;
  		vaddr += PAGE_SIZE * m;
  	}
  
  	/* simple round-robin: */
  	usergart[fmt].last = (usergart[fmt].last + 1) % NUM_USERGART_ENTRIES;
  
  	return 0;
  }
  
  /**
   * omap_gem_fault		-	pagefault handler for GEM objects
   * @vma: the VMA of the GEM object
   * @vmf: fault detail
   *
   * Invoked when a fault occurs on an mmap of a GEM managed area. GEM
   * does most of the work for us including the actual map/unmap calls
   * but we need to do the actual page work.
   *
   * The VMA was set up by GEM. In doing so it also ensured that the
   * vma->vm_private_data points to the GEM object that is backing this
   * mapping.
   */
  int omap_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
  {
  	struct drm_gem_object *obj = vma->vm_private_data;
  	struct omap_gem_object *omap_obj = to_omap_bo(obj);
  	struct drm_device *dev = obj->dev;
  	struct page **pages;
  	int ret;
  
  	/* Make sure we don't parallel update on a fault, nor move or remove
  	 * something from beneath our feet
  	 */
  	mutex_lock(&dev->struct_mutex);
  
  	/* if a shmem backed object, make sure we have pages attached now */
  	ret = get_pages(obj, &pages);
  	if (ret) {
  		goto fail;
  	}
  
  	/* where should we do corresponding put_pages().. we are mapping
  	 * the original page, rather than thru a GART, so we can't rely
  	 * on eviction to trigger this.  But munmap() or all mappings should
  	 * probably trigger put_pages()?
  	 */
  
  	if (omap_obj->flags & OMAP_BO_TILED)
  		ret = fault_2d(obj, vma, vmf);
  	else
  		ret = fault_1d(obj, vma, vmf);
  
  
  fail:
  	mutex_unlock(&dev->struct_mutex);
  	switch (ret) {
  	case 0:
  	case -ERESTARTSYS:
  	case -EINTR:
  		return VM_FAULT_NOPAGE;
  	case -ENOMEM:
  		return VM_FAULT_OOM;
  	default:
  		return VM_FAULT_SIGBUS;
  	}
  }
  
  /** We override mainly to fix up some of the vm mapping flags.. */
  int omap_gem_mmap(struct file *filp, struct vm_area_struct *vma)
  {
  	int ret;
  
  	ret = drm_gem_mmap(filp, vma);
  	if (ret) {
  		DBG("mmap failed: %d", ret);
  		return ret;
  	}
  
  	return omap_gem_mmap_obj(vma->vm_private_data, vma);
  }
  
  int omap_gem_mmap_obj(struct drm_gem_object *obj,
  		struct vm_area_struct *vma)
  {
  	struct omap_gem_object *omap_obj = to_omap_bo(obj);
  
  	vma->vm_flags &= ~VM_PFNMAP;
  	vma->vm_flags |= VM_MIXEDMAP;
  
  	if (omap_obj->flags & OMAP_BO_WC) {
  		vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
  	} else if (omap_obj->flags & OMAP_BO_UNCACHED) {
  		vma->vm_page_prot = pgprot_noncached(vm_get_page_prot(vma->vm_flags));
  	} else {
  		/*
  		 * We do have some private objects, at least for scanout buffers
  		 * on hardware without DMM/TILER.  But these are allocated write-
  		 * combine
  		 */
  		if (WARN_ON(!obj->filp))
  			return -EINVAL;
  
  		/*
  		 * Shunt off cached objs to shmem file so they have their own
  		 * address_space (so unmap_mapping_range does what we want,
  		 * in particular in the case of mmap'd dmabufs)
  		 */
  		fput(vma->vm_file);
  		vma->vm_pgoff = 0;
  		vma->vm_file  = get_file(obj->filp);
  
  		vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
  	}
  
  	return 0;
  }
  
  
  /**
   * omap_gem_dumb_create	-	create a dumb buffer
   * @drm_file: our client file
   * @dev: our device
   * @args: the requested arguments copied from userspace
   *
   * Allocate a buffer suitable for use for a frame buffer of the
   * form described by user space. Give userspace a handle by which
   * to reference it.
   */
  int omap_gem_dumb_create(struct drm_file *file, struct drm_device *dev,
  		struct drm_mode_create_dumb *args)
  {
  	union omap_gem_size gsize;
  
  	/* in case someone tries to feed us a completely bogus stride: */
  	args->pitch = align_pitch(args->pitch, args->width, args->bpp);
  	args->size = PAGE_ALIGN(args->pitch * args->height);
  
  	gsize = (union omap_gem_size){
  		.bytes = args->size,
  	};
  
  	return omap_gem_new_handle(dev, file, gsize,
  			OMAP_BO_SCANOUT | OMAP_BO_WC, &args->handle);
  }
  
  /**
   * omap_gem_dumb_destroy	-	destroy a dumb buffer
   * @file: client file
   * @dev: our DRM device
   * @handle: the object handle
   *
   * Destroy a handle that was created via omap_gem_dumb_create.
   */
  int omap_gem_dumb_destroy(struct drm_file *file, struct drm_device *dev,
  		uint32_t handle)
  {
  	/* No special work needed, drop the reference and see what falls out */
  	return drm_gem_handle_delete(file, handle);
  }
  
  /**
   * omap_gem_dumb_map	-	buffer mapping for dumb interface
   * @file: our drm client file
   * @dev: drm device
   * @handle: GEM handle to the object (from dumb_create)
   *
   * Do the necessary setup to allow the mapping of the frame buffer
   * into user memory. We don't have to do much here at the moment.
   */
  int omap_gem_dumb_map_offset(struct drm_file *file, struct drm_device *dev,
  		uint32_t handle, uint64_t *offset)
  {
  	struct drm_gem_object *obj;
  	int ret = 0;
  
  	/* GEM does all our handle to object mapping */
  	obj = drm_gem_object_lookup(dev, file, handle);
  	if (obj == NULL) {
  		ret = -ENOENT;
  		goto fail;
  	}
  
  	*offset = omap_gem_mmap_offset(obj);
  
  	drm_gem_object_unreference_unlocked(obj);
  
  fail:
  	return ret;
  }
  
  /* Set scrolling position.  This allows us to implement fast scrolling
   * for console.
   *
   * Call only from non-atomic contexts.
   */
  int omap_gem_roll(struct drm_gem_object *obj, uint32_t roll)
  {
  	struct omap_gem_object *omap_obj = to_omap_bo(obj);
  	uint32_t npages = obj->size >> PAGE_SHIFT;
  	int ret = 0;
  
  	if (roll > npages) {
  		dev_err(obj->dev->dev, "invalid roll: %d\n", roll);
  		return -EINVAL;
  	}
  
  	omap_obj->roll = roll;
  
  	mutex_lock(&obj->dev->struct_mutex);
  
  	/* if we aren't mapped yet, we don't need to do anything */
  	if (omap_obj->block) {
  		struct page **pages;
  		ret = get_pages(obj, &pages);
  		if (ret)
  			goto fail;
  		ret = tiler_pin(omap_obj->block, pages, npages, roll, true);
  		if (ret)
  			dev_err(obj->dev->dev, "could not repin: %d\n", ret);
  	}
  
  fail:
  	mutex_unlock(&obj->dev->struct_mutex);
  
  	return ret;
  }
  
  /* Sync the buffer for CPU access.. note pages should already be
   * attached, ie. omap_gem_get_pages()
   */
  void omap_gem_cpu_sync(struct drm_gem_object *obj, int pgoff)
  {
  	struct drm_device *dev = obj->dev;
  	struct omap_gem_object *omap_obj = to_omap_bo(obj);
  
  	if (is_cached_coherent(obj) && omap_obj->addrs[pgoff]) {
  		dma_unmap_page(dev->dev, omap_obj->addrs[pgoff],
  				PAGE_SIZE, DMA_BIDIRECTIONAL);
  		omap_obj->addrs[pgoff] = 0;
  	}
  }
  
  /* sync the buffer for DMA access */
  void omap_gem_dma_sync(struct drm_gem_object *obj,
  		enum dma_data_direction dir)
  {
  	struct drm_device *dev = obj->dev;
  	struct omap_gem_object *omap_obj = to_omap_bo(obj);
  
  	if (is_cached_coherent(obj)) {
  		int i, npages = obj->size >> PAGE_SHIFT;
  		struct page **pages = omap_obj->pages;
  		bool dirty = false;
  
  		for (i = 0; i < npages; i++) {
  			if (!omap_obj->addrs[i]) {
  				omap_obj->addrs[i] = dma_map_page(dev->dev, pages[i], 0,
  						PAGE_SIZE, DMA_BIDIRECTIONAL);
  				dirty = true;
  			}
  		}
  
  		if (dirty) {
  			unmap_mapping_range(obj->filp->f_mapping, 0,
  					omap_gem_mmap_size(obj), 1);
  		}
  	}
  }
  
  /* Get physical address for DMA.. if 'remap' is true, and the buffer is not
   * already contiguous, remap it to pin in physically contiguous memory.. (ie.
   * map in TILER)
   */
  int omap_gem_get_paddr(struct drm_gem_object *obj,
  		dma_addr_t *paddr, bool remap)
  {
  	struct omap_drm_private *priv = obj->dev->dev_private;
  	struct omap_gem_object *omap_obj = to_omap_bo(obj);
  	int ret = 0;
  
  	mutex_lock(&obj->dev->struct_mutex);
  
  	if (remap && is_shmem(obj) && priv->has_dmm) {
  		if (omap_obj->paddr_cnt == 0) {
  			struct page **pages;
  			uint32_t npages = obj->size >> PAGE_SHIFT;
  			enum tiler_fmt fmt = gem2fmt(omap_obj->flags);
  			struct tiler_block *block;
  
  			BUG_ON(omap_obj->block);
  
  			ret = get_pages(obj, &pages);
  			if (ret)
  				goto fail;
  
  			if (omap_obj->flags & OMAP_BO_TILED) {
  				block = tiler_reserve_2d(fmt,
  						omap_obj->width,
  						omap_obj->height, 0);
  			} else {
  				block = tiler_reserve_1d(obj->size);
  			}
  
  			if (IS_ERR(block)) {
  				ret = PTR_ERR(block);
  				dev_err(obj->dev->dev,
  					"could not remap: %d (%d)\n", ret, fmt);
  				goto fail;
  			}
  
  			/* TODO: enable async refill.. */
  			ret = tiler_pin(block, pages, npages,
  					omap_obj->roll, true);
  			if (ret) {
  				tiler_release(block);
  				dev_err(obj->dev->dev,
  						"could not pin: %d\n", ret);
  				goto fail;
  			}
  
  			omap_obj->paddr = tiler_ssptr(block);
  			omap_obj->block = block;
  
  			DBG("got paddr: %08x", omap_obj->paddr);
  		}
  
  		omap_obj->paddr_cnt++;
  
  		*paddr = omap_obj->paddr;
  	} else if (omap_obj->flags & OMAP_BO_DMA) {
  		*paddr = omap_obj->paddr;
  	} else {
  		ret = -EINVAL;
  		goto fail;
  	}
  
  fail:
  	mutex_unlock(&obj->dev->struct_mutex);
  
  	return ret;
  }
  
  /* Release physical address, when DMA is no longer being performed.. this
   * could potentially unpin and unmap buffers from TILER
   */
  int omap_gem_put_paddr(struct drm_gem_object *obj)
  {
  	struct omap_gem_object *omap_obj = to_omap_bo(obj);
  	int ret = 0;
  
  	mutex_lock(&obj->dev->struct_mutex);
  	if (omap_obj->paddr_cnt > 0) {
  		omap_obj->paddr_cnt--;
  		if (omap_obj->paddr_cnt == 0) {
  			ret = tiler_unpin(omap_obj->block);
  			if (ret) {
  				dev_err(obj->dev->dev,
  					"could not unpin pages: %d\n", ret);
  				goto fail;
  			}
  			ret = tiler_release(omap_obj->block);
  			if (ret) {
  				dev_err(obj->dev->dev,
  					"could not release unmap: %d\n", ret);
  			}
  			omap_obj->block = NULL;
  		}
  	}
  fail:
  	mutex_unlock(&obj->dev->struct_mutex);
  	return ret;
  }
  
  /* Get rotated scanout address (only valid if already pinned), at the
   * specified orientation and x,y offset from top-left corner of buffer
   * (only valid for tiled 2d buffers)
   */
  int omap_gem_rotated_paddr(struct drm_gem_object *obj, uint32_t orient,
  		int x, int y, dma_addr_t *paddr)
  {
  	struct omap_gem_object *omap_obj = to_omap_bo(obj);
  	int ret = -EINVAL;
  
  	mutex_lock(&obj->dev->struct_mutex);
  	if ((omap_obj->paddr_cnt > 0) && omap_obj->block &&
  			(omap_obj->flags & OMAP_BO_TILED)) {
  		*paddr = tiler_tsptr(omap_obj->block, orient, x, y);
  		ret = 0;
  	}
  	mutex_unlock(&obj->dev->struct_mutex);
  	return ret;
  }
  
  /* Get tiler stride for the buffer (only valid for 2d tiled buffers) */
  int omap_gem_tiled_stride(struct drm_gem_object *obj, uint32_t orient)
  {
  	struct omap_gem_object *omap_obj = to_omap_bo(obj);
  	int ret = -EINVAL;
  	if (omap_obj->flags & OMAP_BO_TILED)
  		ret = tiler_stride(gem2fmt(omap_obj->flags), orient);
  	return ret;
  }
  
  /* acquire pages when needed (for example, for DMA where physically
   * contiguous buffer is not required
   */
  static int get_pages(struct drm_gem_object *obj, struct page ***pages)
  {
  	struct omap_gem_object *omap_obj = to_omap_bo(obj);
  	int ret = 0;
  
  	if (is_shmem(obj) && !omap_obj->pages) {
  		ret = omap_gem_attach_pages(obj);
  		if (ret) {
  			dev_err(obj->dev->dev, "could not attach pages\n");
  			return ret;
  		}
  	}
  
  	/* TODO: even phys-contig.. we should have a list of pages? */
  	*pages = omap_obj->pages;
  
  	return 0;
  }
  
  /* if !remap, and we don't have pages backing, then fail, rather than
   * increasing the pin count (which we don't really do yet anyways,
   * because we don't support swapping pages back out).  And 'remap'
   * might not be quite the right name, but I wanted to keep it working
   * similarly to omap_gem_get_paddr().  Note though that mutex is not
   * aquired if !remap (because this can be called in atomic ctxt),
   * but probably omap_gem_get_paddr() should be changed to work in the
   * same way.  If !remap, a matching omap_gem_put_pages() call is not
   * required (and should not be made).
   */
  int omap_gem_get_pages(struct drm_gem_object *obj, struct page ***pages,
  		bool remap)
  {
  	int ret;
  	if (!remap) {
  		struct omap_gem_object *omap_obj = to_omap_bo(obj);
  		if (!omap_obj->pages)
  			return -ENOMEM;
  		*pages = omap_obj->pages;
  		return 0;
  	}
  	mutex_lock(&obj->dev->struct_mutex);
  	ret = get_pages(obj, pages);
  	mutex_unlock(&obj->dev->struct_mutex);
  	return ret;
  }
  
  /* release pages when DMA no longer being performed */
  int omap_gem_put_pages(struct drm_gem_object *obj)
  {
  	/* do something here if we dynamically attach/detach pages.. at
  	 * least they would no longer need to be pinned if everyone has
  	 * released the pages..
  	 */
  	return 0;
  }
  
  /* Get kernel virtual address for CPU access.. this more or less only
   * exists for omap_fbdev.  This should be called with struct_mutex
   * held.
   */
  void *omap_gem_vaddr(struct drm_gem_object *obj)
  {
  	struct omap_gem_object *omap_obj = to_omap_bo(obj);
  	WARN_ON(! mutex_is_locked(&obj->dev->struct_mutex));
  	if (!omap_obj->vaddr) {
  		struct page **pages;
  		int ret = get_pages(obj, &pages);
  		if (ret)
  			return ERR_PTR(ret);
  		omap_obj->vaddr = vmap(pages, obj->size >> PAGE_SHIFT,
  				VM_MAP, pgprot_writecombine(PAGE_KERNEL));
  	}
  	return omap_obj->vaddr;
  }
  
  #ifdef CONFIG_DEBUG_FS
  void omap_gem_describe(struct drm_gem_object *obj, struct seq_file *m)
  {
  	struct drm_device *dev = obj->dev;
  	struct omap_gem_object *omap_obj = to_omap_bo(obj);
  	uint64_t off = 0;
  
  	WARN_ON(! mutex_is_locked(&dev->struct_mutex));
  
  	if (obj->map_list.map)
  		off = (uint64_t)obj->map_list.hash.key;
  
  	seq_printf(m, "%08x: %2d (%2d) %08llx %08Zx (%2d) %p %4d",
  			omap_obj->flags, obj->name, obj->refcount.refcount.counter,
  			off, omap_obj->paddr, omap_obj->paddr_cnt,
  			omap_obj->vaddr, omap_obj->roll);
  
  	if (omap_obj->flags & OMAP_BO_TILED) {
  		seq_printf(m, " %dx%d", omap_obj->width, omap_obj->height);
  		if (omap_obj->block) {
  			struct tcm_area *area = &omap_obj->block->area;
  			seq_printf(m, " (%dx%d, %dx%d)",
  					area->p0.x, area->p0.y,
  					area->p1.x, area->p1.y);
  		}
  	} else {
  		seq_printf(m, " %d", obj->size);
  	}
  
  	seq_printf(m, "\n");
  }
  
  void omap_gem_describe_objects(struct list_head *list, struct seq_file *m)
  {
  	struct omap_gem_object *omap_obj;
  	int count = 0;
  	size_t size = 0;
  
  	list_for_each_entry(omap_obj, list, mm_list) {
  		struct drm_gem_object *obj = &omap_obj->base;
  		seq_printf(m, "   ");
  		omap_gem_describe(obj, m);
  		count++;
  		size += obj->size;
  	}
  
  	seq_printf(m, "Total %d objects, %zu bytes\n", count, size);
  }
  #endif
  
  /* Buffer Synchronization:
   */
  
  struct omap_gem_sync_waiter {
  	struct list_head list;
  	struct omap_gem_object *omap_obj;
  	enum omap_gem_op op;
  	uint32_t read_target, write_target;
  	/* notify called w/ sync_lock held */
  	void (*notify)(void *arg);
  	void *arg;
  };
  
  /* list of omap_gem_sync_waiter.. the notify fxn gets called back when
   * the read and/or write target count is achieved which can call a user
   * callback (ex. to kick 3d and/or 2d), wakeup blocked task (prep for
   * cpu access), etc.
   */
  static LIST_HEAD(waiters);
  
  static inline bool is_waiting(struct omap_gem_sync_waiter *waiter)
  {
  	struct omap_gem_object *omap_obj = waiter->omap_obj;
  	if ((waiter->op & OMAP_GEM_READ) &&
  			(omap_obj->sync->read_complete < waiter->read_target))
  		return true;
  	if ((waiter->op & OMAP_GEM_WRITE) &&
  			(omap_obj->sync->write_complete < waiter->write_target))
  		return true;
  	return false;
  }
  
  /* macro for sync debug.. */
  #define SYNCDBG 0
  #define SYNC(fmt, ...) do { if (SYNCDBG) \
  		printk(KERN_ERR "%s:%d: "fmt"\n", \
  				__func__, __LINE__, ##__VA_ARGS__); \
  	} while (0)
  
  
  static void sync_op_update(void)
  {
  	struct omap_gem_sync_waiter *waiter, *n;
  	list_for_each_entry_safe(waiter, n, &waiters, list) {
  		if (!is_waiting(waiter)) {
  			list_del(&waiter->list);
  			SYNC("notify: %p", waiter);
  			waiter->notify(waiter->arg);
  			kfree(waiter);
  		}
  	}
  }
  
  static inline int sync_op(struct drm_gem_object *obj,
  		enum omap_gem_op op, bool start)
  {
  	struct omap_gem_object *omap_obj = to_omap_bo(obj);
  	int ret = 0;
  
  	spin_lock(&sync_lock);
  
  	if (!omap_obj->sync) {
  		omap_obj->sync = kzalloc(sizeof(*omap_obj->sync), GFP_ATOMIC);
  		if (!omap_obj->sync) {
  			ret = -ENOMEM;
  			goto unlock;
  		}
  	}
  
  	if (start) {
  		if (op & OMAP_GEM_READ)
  			omap_obj->sync->read_pending++;
  		if (op & OMAP_GEM_WRITE)
  			omap_obj->sync->write_pending++;
  	} else {
  		if (op & OMAP_GEM_READ)
  			omap_obj->sync->read_complete++;
  		if (op & OMAP_GEM_WRITE)
  			omap_obj->sync->write_complete++;
  		sync_op_update();
  	}
  
  unlock:
  	spin_unlock(&sync_lock);
  
  	return ret;
  }
  
  /* it is a bit lame to handle updates in this sort of polling way, but
   * in case of PVR, the GPU can directly update read/write complete
   * values, and not really tell us which ones it updated.. this also
   * means that sync_lock is not quite sufficient.  So we'll need to
   * do something a bit better when it comes time to add support for
   * separate 2d hw..
   */
  void omap_gem_op_update(void)
  {
  	spin_lock(&sync_lock);
  	sync_op_update();
  	spin_unlock(&sync_lock);
  }
  
  /* mark the start of read and/or write operation */
  int omap_gem_op_start(struct drm_gem_object *obj, enum omap_gem_op op)
  {
  	return sync_op(obj, op, true);
  }
  
  int omap_gem_op_finish(struct drm_gem_object *obj, enum omap_gem_op op)
  {
  	return sync_op(obj, op, false);
  }
  
  static DECLARE_WAIT_QUEUE_HEAD(sync_event);
  
  static void sync_notify(void *arg)
  {
  	struct task_struct **waiter_task = arg;
  	*waiter_task = NULL;
  	wake_up_all(&sync_event);
  }
  
  int omap_gem_op_sync(struct drm_gem_object *obj, enum omap_gem_op op)
  {
  	struct omap_gem_object *omap_obj = to_omap_bo(obj);
  	int ret = 0;
  	if (omap_obj->sync) {
  		struct task_struct *waiter_task = current;
  		struct omap_gem_sync_waiter *waiter =
  				kzalloc(sizeof(*waiter), GFP_KERNEL);
  
  		if (!waiter) {
  			return -ENOMEM;
  		}
  
  		waiter->omap_obj = omap_obj;
  		waiter->op = op;
  		waiter->read_target = omap_obj->sync->read_pending;
  		waiter->write_target = omap_obj->sync->write_pending;
  		waiter->notify = sync_notify;
  		waiter->arg = &waiter_task;
  
  		spin_lock(&sync_lock);
  		if (is_waiting(waiter)) {
  			SYNC("waited: %p", waiter);
  			list_add_tail(&waiter->list, &waiters);
  			spin_unlock(&sync_lock);
  			ret = wait_event_interruptible(sync_event,
  					(waiter_task == NULL));
  			spin_lock(&sync_lock);
  			if (waiter_task) {
  				SYNC("interrupted: %p", waiter);
  				/* we were interrupted */
  				list_del(&waiter->list);
  				waiter_task = NULL;
  			} else {
  				/* freed in sync_op_update() */
  				waiter = NULL;
  			}
  		}
  		spin_unlock(&sync_lock);
  
  		if (waiter) {
  			kfree(waiter);
  		}
  	}
  	return ret;
  }
  
  /* call fxn(arg), either synchronously or asynchronously if the op
   * is currently blocked..  fxn() can be called from any context
   *
   * (TODO for now fxn is called back from whichever context calls
   * omap_gem_op_update().. but this could be better defined later
   * if needed)
   *
   * TODO more code in common w/ _sync()..
   */
  int omap_gem_op_async(struct drm_gem_object *obj, enum omap_gem_op op,
  		void (*fxn)(void *arg), void *arg)
  {
  	struct omap_gem_object *omap_obj = to_omap_bo(obj);
  	if (omap_obj->sync) {
  		struct omap_gem_sync_waiter *waiter =
  				kzalloc(sizeof(*waiter), GFP_ATOMIC);
  
  		if (!waiter) {
  			return -ENOMEM;
  		}
  
  		waiter->omap_obj = omap_obj;
  		waiter->op = op;
  		waiter->read_target = omap_obj->sync->read_pending;
  		waiter->write_target = omap_obj->sync->write_pending;
  		waiter->notify = fxn;
  		waiter->arg = arg;
  
  		spin_lock(&sync_lock);
  		if (is_waiting(waiter)) {
  			SYNC("waited: %p", waiter);
  			list_add_tail(&waiter->list, &waiters);
  			spin_unlock(&sync_lock);
  			return 0;
  		}
  
  		spin_unlock(&sync_lock);
  	}
  
  	/* no waiting.. */
  	fxn(arg);
  
  	return 0;
  }
  
  /* special API so PVR can update the buffer to use a sync-object allocated
   * from it's sync-obj heap.  Only used for a newly allocated (from PVR's
   * perspective) sync-object, so we overwrite the new syncobj w/ values
   * from the already allocated syncobj (if there is one)
   */
  int omap_gem_set_sync_object(struct drm_gem_object *obj, void *syncobj)
  {
  	struct omap_gem_object *omap_obj = to_omap_bo(obj);
  	int ret = 0;
  
  	spin_lock(&sync_lock);
  
  	if ((omap_obj->flags & OMAP_BO_EXT_SYNC) && !syncobj) {
  		/* clearing a previously set syncobj */
  		syncobj = kzalloc(sizeof(*omap_obj->sync), GFP_ATOMIC);
  		if (!syncobj) {
  			ret = -ENOMEM;
  			goto unlock;
  		}
  		memcpy(syncobj, omap_obj->sync, sizeof(*omap_obj->sync));
  		omap_obj->flags &= ~OMAP_BO_EXT_SYNC;
  		omap_obj->sync = syncobj;
  	} else if (syncobj && !(omap_obj->flags & OMAP_BO_EXT_SYNC)) {
  		/* replacing an existing syncobj */
  		if (omap_obj->sync) {
  			memcpy(syncobj, omap_obj->sync, sizeof(*omap_obj->sync));
  			kfree(omap_obj->sync);
  		}
  		omap_obj->flags |= OMAP_BO_EXT_SYNC;
  		omap_obj->sync = syncobj;
  	}
  
  unlock:
  	spin_unlock(&sync_lock);
  	return ret;
  }
  
  int omap_gem_init_object(struct drm_gem_object *obj)
  {
  	return -EINVAL;          /* unused */
  }
  
  /* don't call directly.. called from GEM core when it is time to actually
   * free the object..
   */
  void omap_gem_free_object(struct drm_gem_object *obj)
  {
  	struct drm_device *dev = obj->dev;
  	struct omap_gem_object *omap_obj = to_omap_bo(obj);
  
  	evict(obj);
  
  	WARN_ON(!mutex_is_locked(&dev->struct_mutex));
  
  	list_del(&omap_obj->mm_list);
  
  	if (obj->map_list.map) {
  		drm_gem_free_mmap_offset(obj);
  	}
  
  	/* this means the object is still pinned.. which really should
  	 * not happen.  I think..
  	 */
  	WARN_ON(omap_obj->paddr_cnt > 0);
  
  	/* don't free externally allocated backing memory */
  	if (!(omap_obj->flags & OMAP_BO_EXT_MEM)) {
  		if (omap_obj->pages) {
  			omap_gem_detach_pages(obj);
  		}
  		if (!is_shmem(obj)) {
  			dma_free_writecombine(dev->dev, obj->size,
  					omap_obj->vaddr, omap_obj->paddr);
  		} else if (omap_obj->vaddr) {
  			vunmap(omap_obj->vaddr);
  		}
  	}
  
  	/* don't free externally allocated syncobj */
  	if (!(omap_obj->flags & OMAP_BO_EXT_SYNC)) {
  		kfree(omap_obj->sync);
  	}
  
  	drm_gem_object_release(obj);
  
  	kfree(obj);
  }
  
  /* convenience method to construct a GEM buffer object, and userspace handle */
  int omap_gem_new_handle(struct drm_device *dev, struct drm_file *file,
  		union omap_gem_size gsize, uint32_t flags, uint32_t *handle)
  {
  	struct drm_gem_object *obj;
  	int ret;
  
  	obj = omap_gem_new(dev, gsize, flags);
  	if (!obj)
  		return -ENOMEM;
  
  	ret = drm_gem_handle_create(file, obj, handle);
  	if (ret) {
  		drm_gem_object_release(obj);
  		kfree(obj); /* TODO isn't there a dtor to call? just copying i915 */
  		return ret;
  	}
  
  	/* drop reference from allocate - handle holds it now */
  	drm_gem_object_unreference_unlocked(obj);
  
  	return 0;
  }
  
  /* GEM buffer object constructor */
  struct drm_gem_object *omap_gem_new(struct drm_device *dev,
  		union omap_gem_size gsize, uint32_t flags)
  {
  	struct omap_drm_private *priv = dev->dev_private;
  	struct omap_gem_object *omap_obj;
  	struct drm_gem_object *obj = NULL;
  	size_t size;
  	int ret;
  
  	if (flags & OMAP_BO_TILED) {
  		if (!usergart) {
  			dev_err(dev->dev, "Tiled buffers require DMM\n");
  			goto fail;
  		}
  
  		/* tiled buffers are always shmem paged backed.. when they are
  		 * scanned out, they are remapped into DMM/TILER
  		 */
  		flags &= ~OMAP_BO_SCANOUT;
  
  		/* currently don't allow cached buffers.. there is some caching
  		 * stuff that needs to be handled better
  		 */
  		flags &= ~(OMAP_BO_CACHED|OMAP_BO_UNCACHED);
  		flags |= OMAP_BO_WC;
  
  		/* align dimensions to slot boundaries... */
  		tiler_align(gem2fmt(flags),
  				&gsize.tiled.width, &gsize.tiled.height);
  
  		/* ...and calculate size based on aligned dimensions */
  		size = tiler_size(gem2fmt(flags),
  				gsize.tiled.width, gsize.tiled.height);
  	} else {
  		size = PAGE_ALIGN(gsize.bytes);
  	}
  
  	omap_obj = kzalloc(sizeof(*omap_obj), GFP_KERNEL);
  	if (!omap_obj) {
  		dev_err(dev->dev, "could not allocate GEM object\n");
  		goto fail;
  	}
  
  	list_add(&omap_obj->mm_list, &priv->obj_list);
  
  	obj = &omap_obj->base;
  
  	if ((flags & OMAP_BO_SCANOUT) && !priv->has_dmm) {
  		/* attempt to allocate contiguous memory if we don't
  		 * have DMM for remappign discontiguous buffers
  		 */
  		omap_obj->vaddr =  dma_alloc_writecombine(dev->dev, size,
  				&omap_obj->paddr, GFP_KERNEL);
  		if (omap_obj->vaddr) {
  			flags |= OMAP_BO_DMA;
  		}
  	}
  
  	omap_obj->flags = flags;
  
  	if (flags & OMAP_BO_TILED) {
  		omap_obj->width = gsize.tiled.width;
  		omap_obj->height = gsize.tiled.height;
  	}
  
  	if (flags & (OMAP_BO_DMA|OMAP_BO_EXT_MEM)) {
  		ret = drm_gem_private_object_init(dev, obj, size);
  	} else {
  		ret = drm_gem_object_init(dev, obj, size);
  	}
  
  	if (ret) {
  		goto fail;
  	}
  
  	return obj;
  
  fail:
  	if (obj) {
  		omap_gem_free_object(obj);
  	}
  	return NULL;
  }
  
  /* init/cleanup.. if DMM is used, we need to set some stuff up.. */
  void omap_gem_init(struct drm_device *dev)
  {
  	struct omap_drm_private *priv = dev->dev_private;
  	const enum tiler_fmt fmts[] = {
  			TILFMT_8BIT, TILFMT_16BIT, TILFMT_32BIT
  	};
  	int i, j;
  
  	if (!dmm_is_initialized()) {
  		/* DMM only supported on OMAP4 and later, so this isn't fatal */
  		dev_warn(dev->dev, "DMM not available, disable DMM support\n");
  		return;
  	}
  
  	usergart = kzalloc(3 * sizeof(*usergart), GFP_KERNEL);
  	if (!usergart) {
  		dev_warn(dev->dev, "could not allocate usergart\n");
  		return;
  	}
  
  	/* reserve 4k aligned/wide regions for userspace mappings: */
  	for (i = 0; i < ARRAY_SIZE(fmts); i++) {
  		uint16_t h = 1, w = PAGE_SIZE >> i;
  		tiler_align(fmts[i], &w, &h);
  		/* note: since each region is 1 4kb page wide, and minimum
  		 * number of rows, the height ends up being the same as the
  		 * # of pages in the region
  		 */
  		usergart[i].height = h;
  		usergart[i].height_shift = ilog2(h);
  		usergart[i].stride_pfn = tiler_stride(fmts[i], 0) >> PAGE_SHIFT;
  		usergart[i].slot_shift = ilog2((PAGE_SIZE / h) >> i);
  		for (j = 0; j < NUM_USERGART_ENTRIES; j++) {
  			struct usergart_entry *entry = &usergart[i].entry[j];
  			struct tiler_block *block =
  					tiler_reserve_2d(fmts[i], w, h,
  							PAGE_SIZE);
  			if (IS_ERR(block)) {
  				dev_err(dev->dev,
  						"reserve failed: %d, %d, %ld\n",
  						i, j, PTR_ERR(block));
  				return;
  			}
  			entry->paddr = tiler_ssptr(block);
  			entry->block = block;
  
  			DBG("%d:%d: %dx%d: paddr=%08x stride=%d", i, j, w, h,
  					entry->paddr,
  					usergart[i].stride_pfn << PAGE_SHIFT);
  		}
  	}
  
  	priv->has_dmm = true;
  }
  
  void omap_gem_deinit(struct drm_device *dev)
  {
  	/* I believe we can rely on there being no more outstanding GEM
  	 * objects which could depend on usergart/dmm at this point.
  	 */
  	kfree(usergart);
  }
  