// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2011 Texas Instruments Incorporated - https://www.ti.com/
 * Author: Rob Clark <rob.clark@linaro.org>
 */

#include <linux/dma-mapping.h>
#include <linux/seq_file.h>
#include <linux/shmem_fs.h>
#include <linux/spinlock.h>
#include <linux/vmalloc.h>

#include <drm/drm_dumb_buffers.h>
#include <drm/drm_prime.h>
#include <drm/drm_print.h>
#include <drm/drm_vma_manager.h>

#include "omap_drv.h"
#include "omap_dmm_tiler.h"

/*
 * GEM buffer object implementation.
 */

/* note: we use upper 8 bits of flags for driver-internal flags: */
#define OMAP_BO_MEM_DMA_API     0x01000000      /* memory allocated with the dma_alloc_* API */
#define OMAP_BO_MEM_SHMEM       0x02000000      /* memory allocated through shmem backing */
#define OMAP_BO_MEM_DMABUF      0x08000000      /* memory imported from a dmabuf */

struct omap_gem_object {
        struct drm_gem_object base;

        struct list_head mm_list;

        u32 flags;

        /** width/height for tiled formats (rounded up to slot boundaries) */
        u16 width, height;

        /** roll applied when mapping to DMM */
        u32 roll;

        /** protects pin_cnt, block, pages, dma_addrs and vaddr */
        struct mutex lock;

        /**
         * dma_addr contains the buffer DMA address. It is valid for
         *
         * - buffers allocated through the DMA mapping API (with the
         *   OMAP_BO_MEM_DMA_API flag set)
         *
         * - buffers imported from dmabuf (with the OMAP_BO_MEM_DMABUF flag set)
         *   if they are physically contiguous
         *
         * - buffers mapped through the TILER when pin_cnt is not zero, in which
         *   case the DMA address points to the TILER aperture
         *
         * Physically contiguous buffers have their DMA address equal to the
         * physical address as we don't remap those buffers through the TILER.
         *
         * Buffers mapped to the TILER have their DMA address pointing to the
         * TILER aperture. As TILER mappings are refcounted (through pin_cnt)
         * the DMA address must be accessed through omap_gem_pin() to ensure
         * that the mapping won't disappear unexpectedly. References must be
         * released with omap_gem_unpin().
         */
        dma_addr_t dma_addr;

        /**
         * # of users
         */
        refcount_t pin_cnt;

        /**
         * If the buffer has been imported from a dmabuf the OMAP_DB_DMABUF flag
         * is set and the sgt field is valid.
         */
        struct sg_table *sgt;

        /**
         * 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 *dma_addrs;

        /**
         * Virtual address, if mapped.
         */
        void *vaddr;
};

#define to_omap_bo(x) container_of(x, struct omap_gem_object, base)

/* 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 omap_drm_usergart_entry {
        struct tiler_block *block;      /* the reserved tiler block */
        dma_addr_t dma_addr;
        struct drm_gem_object *obj;     /* the current pinned obj */
        pgoff_t obj_pgoff;              /* page offset of obj currently
                                           mapped in */
};

struct omap_drm_usergart {
        struct omap_drm_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 */
};

/* -----------------------------------------------------------------------------
 * Helpers
 */

/** get mmap offset */
u64 omap_gem_mmap_offset(struct drm_gem_object *obj)
{
        struct drm_device *dev = obj->dev;
        int ret;
        size_t size;

        /* Make it mmapable */
        size = omap_gem_mmap_size(obj);
        ret = drm_gem_create_mmap_offset_size(obj, size);
        if (ret) {
                dev_err(dev->dev, "could not allocate mmap offset\n");
                return 0;
        }

        return drm_vma_node_offset_addr(&obj->vma_node);
}

static bool omap_gem_sgt_is_contiguous(struct sg_table *sgt, size_t size)
{
        return !(drm_prime_get_contiguous_size(sgt) < size);
}

static bool omap_gem_is_contiguous(struct omap_gem_object *omap_obj)
{
        if (omap_obj->flags & OMAP_BO_MEM_DMA_API)
                return true;

        if ((omap_obj->flags & OMAP_BO_MEM_DMABUF) &&
            omap_gem_sgt_is_contiguous(omap_obj->sgt, omap_obj->base.size))
                return true;

        return false;
}

/* -----------------------------------------------------------------------------
 * Eviction
 */

static void omap_gem_evict_entry(struct drm_gem_object *obj,
                enum tiler_fmt fmt, struct omap_drm_usergart_entry *entry)
{
        struct omap_gem_object *omap_obj = to_omap_bo(obj);
        struct omap_drm_private *priv = obj->dev->dev_private;
        int n = priv->usergart[fmt].height;
        size_t size = PAGE_SIZE * n;
        loff_t off = omap_gem_mmap_offset(obj) +
                        (entry->obj_pgoff << PAGE_SHIFT);
        const int m = DIV_ROUND_UP(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->anon_inode->i_mapping,
                                            off, PAGE_SIZE, 1);
                        off += PAGE_SIZE * m;
                }
        } else {
                unmap_mapping_range(obj->dev->anon_inode->i_mapping,
                                    off, size, 1);
        }

        entry->obj = NULL;
}

/* Evict a buffer from usergart, if it is mapped there */
static void omap_gem_evict(struct drm_gem_object *obj)
{
        struct omap_gem_object *omap_obj = to_omap_bo(obj);
        struct omap_drm_private *priv = obj->dev->dev_private;

        if (omap_obj->flags & OMAP_BO_TILED_MASK) {
                enum tiler_fmt fmt = gem2fmt(omap_obj->flags);
                int i;

                for (i = 0; i < NUM_USERGART_ENTRIES; i++) {
                        struct omap_drm_usergart_entry *entry =
                                &priv->usergart[fmt].entry[i];

                        if (entry->obj == obj)
                                omap_gem_evict_entry(obj, fmt, entry);
                }
        }
}

/* -----------------------------------------------------------------------------
 * Page Management
 */

/*
 * Ensure backing pages are allocated. Must be called with the omap_obj.lock
 * held.
 */
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;

        lockdep_assert_held(&omap_obj->lock);

        /*
         * If not using shmem (in which case backing pages don't need to be
         * allocated) or if pages are already allocated we're done.
         */
        if (!(omap_obj->flags & OMAP_BO_MEM_SHMEM) || omap_obj->pages)
                return 0;

        pages = drm_gem_get_pages(obj);
        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_objs(*addrs, npages);
                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_TO_DEVICE);

                        if (dma_mapping_error(dev->dev, addrs[i])) {
                                dev_warn(dev->dev,
                                        "%s: failed to map page\n", __func__);

                                for (i = i - 1; i >= 0; --i) {
                                        dma_unmap_page(dev->dev, addrs[i],
                                                PAGE_SIZE, DMA_TO_DEVICE);
                                }

                                ret = -ENOMEM;
                                goto free_addrs;
                        }
                }
        } else {
                addrs = kzalloc_objs(*addrs, npages);
                if (!addrs) {
                        ret = -ENOMEM;
                        goto free_pages;
                }
        }

        omap_obj->dma_addrs = addrs;
        omap_obj->pages = pages;

        return 0;

free_addrs:
        kfree(addrs);
free_pages:
        drm_gem_put_pages(obj, pages, true, false);

        return ret;
}

/* Release backing pages. Must be called with the omap_obj.lock held. */
static void omap_gem_detach_pages(struct drm_gem_object *obj)
{
        struct omap_gem_object *omap_obj = to_omap_bo(obj);
        unsigned int npages = obj->size >> PAGE_SHIFT;
        unsigned int i;

        lockdep_assert_held(&omap_obj->lock);

        for (i = 0; i < npages; i++) {
                if (omap_obj->dma_addrs[i])
                        dma_unmap_page(obj->dev->dev, omap_obj->dma_addrs[i],
                                       PAGE_SIZE, DMA_TO_DEVICE);
        }

        kfree(omap_obj->dma_addrs);
        omap_obj->dma_addrs = NULL;

        drm_gem_put_pages(obj, omap_obj->pages, true, false);
        omap_obj->pages = NULL;
}

/* get buffer flags */
u32 omap_gem_flags(struct drm_gem_object *obj)
{
        return to_omap_bo(obj)->flags;
}

/** 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_MASK) {
                /* 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;
}

/* -----------------------------------------------------------------------------
 * Fault Handling
 */

/* Normal handling for the case of faulting in non-tiled buffers */
static vm_fault_t omap_gem_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 = (vmf->address - vma->vm_start) >> PAGE_SHIFT;

        if (omap_obj->pages) {
                omap_gem_cpu_sync_page(obj, pgoff);
                pfn = page_to_pfn(omap_obj->pages[pgoff]);
        } else {
                BUG_ON(!omap_gem_is_contiguous(omap_obj));
                pfn = (omap_obj->dma_addr >> PAGE_SHIFT) + pgoff;
        }

        VERB("Inserting %p pfn %lx, pa %lx", (void *)vmf->address,
                        pfn, pfn << PAGE_SHIFT);

        return vmf_insert_mixed(vma, vmf->address, pfn);
}

/* Special handling for the case of faulting in 2d tiled buffers */
static vm_fault_t omap_gem_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 omap_drm_private *priv = obj->dev->dev_private;
        struct omap_drm_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;
        unsigned long vaddr;
        int i, err, slots;
        vm_fault_t ret = VM_FAULT_NOPAGE;

        /*
         * 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 = priv->usergart[fmt].height;
        const int n_shift = priv->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 = DIV_ROUND_UP(omap_obj->width << fmt, PAGE_SIZE);

        /* We don't use vmf->pgoff since that has the fake offset: */
        pgoff = (vmf->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 >> priv->usergart[fmt].slot_shift;

        vaddr = vmf->address - ((pgoff - base_pgoff) << PAGE_SHIFT);

        entry = &priv->usergart[fmt].entry[priv->usergart[fmt].last];

        /* evict previous buffer using this usergart entry, if any: */
        if (entry->obj)
                omap_gem_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));

        err = tiler_pin(entry->block, pages, ARRAY_SIZE(pages), 0, true);
        if (err) {
                ret = vmf_error(err);
                dev_err(obj->dev->dev, "failed to pin: %d\n", err);
                return ret;
        }

        pfn = entry->dma_addr >> PAGE_SHIFT;

        VERB("Inserting %p pfn %lx, pa %lx", (void *)vmf->address,
                        pfn, pfn << PAGE_SHIFT);

        for (i = n; i > 0; i--) {
                ret = vmf_insert_mixed(vma, vaddr, pfn);
                if (ret & VM_FAULT_ERROR)
                        break;
                pfn += priv->usergart[fmt].stride_pfn;
                vaddr += PAGE_SIZE * m;
        }

        /* simple round-robin: */
        priv->usergart[fmt].last = (priv->usergart[fmt].last + 1)
                                 % NUM_USERGART_ENTRIES;

        return ret;
}

/**
 * omap_gem_fault               -       pagefault handler for GEM objects
 * @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.
 */
static vm_fault_t omap_gem_fault(struct vm_fault *vmf)
{
        struct vm_area_struct *vma = vmf->vma;
        struct drm_gem_object *obj = vma->vm_private_data;
        struct omap_gem_object *omap_obj = to_omap_bo(obj);
        int err;
        vm_fault_t ret;

        /* Make sure we don't parallel update on a fault, nor move or remove
         * something from beneath our feet
         */
        mutex_lock(&omap_obj->lock);

        /* if a shmem backed object, make sure we have pages attached now */
        err = omap_gem_attach_pages(obj);
        if (err) {
                ret = vmf_error(err);
                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_MASK)
                ret = omap_gem_fault_2d(obj, vma, vmf);
        else
                ret = omap_gem_fault_1d(obj, vma, vmf);


fail:
        mutex_unlock(&omap_obj->lock);
        return ret;
}

static int omap_gem_object_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
{
        struct omap_gem_object *omap_obj = to_omap_bo(obj);

        vm_flags_set(vma, VM_DONTEXPAND | VM_DONTDUMP | VM_IO | 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)
                 */
                vma->vm_pgoff -= drm_vma_node_start(&obj->vma_node);
                vma_set_file(vma, obj->filp);

                vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
        }

        vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot);

        return 0;
}

/* -----------------------------------------------------------------------------
 * Dumb Buffers
 */

/**
 * omap_gem_dumb_create -       create a dumb buffer
 * @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 = { };
        int ret;

        ret = drm_mode_size_dumb(dev, args, SZ_8, 0);
        if (ret)
                return ret;
        gsize.bytes = args->size;

        return omap_gem_new_handle(dev, file, gsize,
                        OMAP_BO_SCANOUT | OMAP_BO_WC, &args->handle);
}

/**
 * omap_gem_dumb_map_offset - create an offset for a dumb buffer
 * @file: our drm client file
 * @dev: drm device
 * @handle: GEM handle to the object (from dumb_create)
 * @offset: memory map offset placeholder
 *
 * 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,
                u32 handle, u64 *offset)
{
        struct drm_gem_object *obj;
        int ret = 0;

        /* GEM does all our handle to object mapping */
        obj = drm_gem_object_lookup(file, handle);
        if (obj == NULL) {
                ret = -ENOENT;
                goto fail;
        }

        *offset = omap_gem_mmap_offset(obj);

        drm_gem_object_put(obj);

fail:
        return ret;
}

#ifdef CONFIG_DRM_FBDEV_EMULATION
/* 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, u32 roll)
{
        struct omap_gem_object *omap_obj = to_omap_bo(obj);
        u32 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(&omap_obj->lock);

        /* if we aren't mapped yet, we don't need to do anything */
        if (omap_obj->block) {
                ret = omap_gem_attach_pages(obj);
                if (ret)
                        goto fail;

                ret = tiler_pin(omap_obj->block, omap_obj->pages, npages,
                                roll, true);
                if (ret)
                        dev_err(obj->dev->dev, "could not repin: %d\n", ret);
        }

fail:
        mutex_unlock(&omap_obj->lock);

        return ret;
}
#endif

/* -----------------------------------------------------------------------------
 * Memory Management & DMA Sync
 */

/*
 * shmem buffers that are mapped cached are not coherent.
 *
 * We keep track of dirty pages using page faulting to perform cache management.
 * When a page is mapped to the CPU in read/write mode the device can't access
 * it and omap_obj->dma_addrs[i] is NULL. When a page is mapped to the device
 * the omap_obj->dma_addrs[i] is set to the DMA address, and the page is
 * unmapped from the CPU.
 */
static inline bool omap_gem_is_cached_coherent(struct drm_gem_object *obj)
{
        struct omap_gem_object *omap_obj = to_omap_bo(obj);

        return !((omap_obj->flags & OMAP_BO_MEM_SHMEM) &&
                ((omap_obj->flags & OMAP_BO_CACHE_MASK) == OMAP_BO_CACHED));
}

/* Sync the buffer for CPU access.. note pages should already be
 * attached, ie. omap_gem_get_pages()
 */
void omap_gem_cpu_sync_page(struct drm_gem_object *obj, int pgoff)
{
        struct drm_device *dev = obj->dev;
        struct omap_gem_object *omap_obj = to_omap_bo(obj);

        if (omap_gem_is_cached_coherent(obj))
                return;

        if (omap_obj->dma_addrs[pgoff]) {
                dma_unmap_page(dev->dev, omap_obj->dma_addrs[pgoff],
                                PAGE_SIZE, DMA_TO_DEVICE);
                omap_obj->dma_addrs[pgoff] = 0;
        }
}

/* sync the buffer for DMA access */
void omap_gem_dma_sync_buffer(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);
        int i, npages = obj->size >> PAGE_SHIFT;
        struct page **pages = omap_obj->pages;
        bool dirty = false;

        if (omap_gem_is_cached_coherent(obj))
                return;

        for (i = 0; i < npages; i++) {
                if (!omap_obj->dma_addrs[i]) {
                        dma_addr_t addr;

                        addr = dma_map_page(dev->dev, pages[i], 0,
                                            PAGE_SIZE, dir);
                        if (dma_mapping_error(dev->dev, addr)) {
                                dev_warn(dev->dev, "%s: failed to map page\n",
                                        __func__);
                                break;
                        }

                        dirty = true;
                        omap_obj->dma_addrs[i] = addr;
                }
        }

        if (dirty) {
                unmap_mapping_range(obj->filp->f_mapping, 0,
                                    omap_gem_mmap_size(obj), 1);
        }
}

static int omap_gem_pin_tiler(struct drm_gem_object *obj)
{
        struct omap_gem_object *omap_obj = to_omap_bo(obj);
        u32 npages = obj->size >> PAGE_SHIFT;
        enum tiler_fmt fmt = gem2fmt(omap_obj->flags);
        struct tiler_block *block;
        int ret;

        BUG_ON(omap_obj->block);

        if (omap_obj->flags & OMAP_BO_TILED_MASK) {
                block = tiler_reserve_2d(fmt, omap_obj->width, omap_obj->height,
                                         PAGE_SIZE);
        } 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, omap_obj->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->dma_addr = tiler_ssptr(block);
        omap_obj->block = block;

        DBG("got dma address: %pad", &omap_obj->dma_addr);

fail:
        return ret;
}

/**
 * omap_gem_pin() - Pin a GEM object in memory
 * @obj: the GEM object
 * @dma_addr: the DMA address
 *
 * Pin the given GEM object in memory and fill the dma_addr pointer with the
 * object's DMA address. If the buffer is not physically contiguous it will be
 * remapped through the TILER to provide a contiguous view.
 *
 * Pins are reference-counted, calling this function multiple times is allowed
 * as long the corresponding omap_gem_unpin() calls are balanced.
 *
 * Return 0 on success or a negative error code otherwise.
 */
int omap_gem_pin(struct drm_gem_object *obj, dma_addr_t *dma_addr)
{
        struct omap_drm_private *priv = obj->dev->dev_private;
        struct omap_gem_object *omap_obj = to_omap_bo(obj);
        int ret = 0;

        mutex_lock(&omap_obj->lock);

        if (!omap_gem_is_contiguous(omap_obj)) {
                if (refcount_read(&omap_obj->pin_cnt) == 0) {

                        refcount_set(&omap_obj->pin_cnt, 1);

                        ret = omap_gem_attach_pages(obj);
                        if (ret)
                                goto fail;

                        if (omap_obj->flags & OMAP_BO_SCANOUT) {
                                if (priv->has_dmm) {
                                        ret = omap_gem_pin_tiler(obj);
                                        if (ret)
                                                goto fail;
                                }
                        }
                } else {
                        refcount_inc(&omap_obj->pin_cnt);
                }
        }

        if (dma_addr)
                *dma_addr = omap_obj->dma_addr;

fail:
        mutex_unlock(&omap_obj->lock);

        return ret;
}

/**
 * omap_gem_unpin_locked() - Unpin a GEM object from memory
 * @obj: the GEM object
 *
 * omap_gem_unpin() without locking.
 */
static void omap_gem_unpin_locked(struct drm_gem_object *obj)
{
        struct omap_drm_private *priv = obj->dev->dev_private;
        struct omap_gem_object *omap_obj = to_omap_bo(obj);
        int ret;

        if (omap_gem_is_contiguous(omap_obj))
                return;

        if (refcount_dec_and_test(&omap_obj->pin_cnt)) {
                if (omap_obj->sgt) {
                        sg_free_table(omap_obj->sgt);
                        kfree(omap_obj->sgt);
                        omap_obj->sgt = NULL;
                }
                if (!(omap_obj->flags & OMAP_BO_SCANOUT))
                        return;
                if (priv->has_dmm) {
                        ret = tiler_unpin(omap_obj->block);
                        if (ret) {
                                dev_err(obj->dev->dev,
                                        "could not unpin pages: %d\n", ret);
                        }
                        ret = tiler_release(omap_obj->block);
                        if (ret) {
                                dev_err(obj->dev->dev,
                                        "could not release unmap: %d\n", ret);
                        }
                        omap_obj->dma_addr = 0;
                        omap_obj->block = NULL;
                }
        }
}

/**
 * omap_gem_unpin() - Unpin a GEM object from memory
 * @obj: the GEM object
 *
 * Unpin the given GEM object previously pinned with omap_gem_pin(). Pins are
 * reference-counted, the actual unpin will only be performed when the number
 * of calls to this function matches the number of calls to omap_gem_pin().
 */
void omap_gem_unpin(struct drm_gem_object *obj)
{
        struct omap_gem_object *omap_obj = to_omap_bo(obj);

        mutex_lock(&omap_obj->lock);
        omap_gem_unpin_locked(obj);
        mutex_unlock(&omap_obj->lock);
}

/* 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_dma_addr(struct drm_gem_object *obj, u32 orient,
                int x, int y, dma_addr_t *dma_addr)
{
        struct omap_gem_object *omap_obj = to_omap_bo(obj);
        int ret = -EINVAL;

        mutex_lock(&omap_obj->lock);

        if ((refcount_read(&omap_obj->pin_cnt) > 0) && omap_obj->block &&
                        (omap_obj->flags & OMAP_BO_TILED_MASK)) {
                *dma_addr = tiler_tsptr(omap_obj->block, orient, x, y);
                ret = 0;
        }

        mutex_unlock(&omap_obj->lock);

        return ret;
}

/* Get tiler stride for the buffer (only valid for 2d tiled buffers) */
int omap_gem_tiled_stride(struct drm_gem_object *obj, u32 orient)
{
        struct omap_gem_object *omap_obj = to_omap_bo(obj);
        int ret = -EINVAL;
        if (omap_obj->flags & OMAP_BO_TILED_MASK)
                ret = tiler_stride(gem2fmt(omap_obj->flags), orient);
        return ret;
}

/* 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_pin().  Note though that mutex is not
 * aquired if !remap (because this can be called in atomic ctxt),
 * but probably omap_gem_unpin() 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)
{
        struct omap_gem_object *omap_obj = to_omap_bo(obj);
        int ret = 0;

        mutex_lock(&omap_obj->lock);

        if (remap) {
                ret = omap_gem_attach_pages(obj);
                if (ret)
                        goto unlock;
        }

        if (!omap_obj->pages) {
                ret = -ENOMEM;
                goto unlock;
        }

        *pages = omap_obj->pages;

unlock:
        mutex_unlock(&omap_obj->lock);

        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;
}

struct sg_table *omap_gem_get_sg(struct drm_gem_object *obj,
                enum dma_data_direction dir)
{
        struct omap_gem_object *omap_obj = to_omap_bo(obj);
        dma_addr_t addr;
        struct sg_table *sgt;
        struct scatterlist *sg;
        unsigned int count, len, stride, i;
        int ret;

        ret = omap_gem_pin(obj, &addr);
        if (ret)
                return ERR_PTR(ret);

        mutex_lock(&omap_obj->lock);

        sgt = omap_obj->sgt;
        if (sgt)
                goto out;

        sgt = kzalloc_obj(*sgt);
        if (!sgt) {
                ret = -ENOMEM;
                goto err_unpin;
        }

        if (addr) {
                if (omap_obj->flags & OMAP_BO_TILED_MASK) {
                        enum tiler_fmt fmt = gem2fmt(omap_obj->flags);

                        len = omap_obj->width << (int)fmt;
                        count = omap_obj->height;
                        stride = tiler_stride(fmt, 0);
                } else {
                        len = obj->size;
                        count = 1;
                        stride = 0;
                }
        } else {
                count = obj->size >> PAGE_SHIFT;
        }

        ret = sg_alloc_table(sgt, count, GFP_KERNEL);
        if (ret)
                goto err_free;

        /* this must be after omap_gem_pin() to ensure we have pages attached */
        omap_gem_dma_sync_buffer(obj, dir);

        if (addr) {
                for_each_sg(sgt->sgl, sg, count, i) {
                        sg_set_page(sg, pfn_to_page(__phys_to_pfn(addr)),
                                    len, offset_in_page(addr));
                        sg_dma_address(sg) = addr;
                        sg_dma_len(sg) = len;

                        addr += stride;
                }
        } else {
                for_each_sg(sgt->sgl, sg, count, i) {
                        sg_set_page(sg, omap_obj->pages[i], PAGE_SIZE, 0);
                        sg_dma_address(sg) = omap_obj->dma_addrs[i];
                        sg_dma_len(sg) =  PAGE_SIZE;
                }
        }

        omap_obj->sgt = sgt;
out:
        mutex_unlock(&omap_obj->lock);
        return sgt;

err_free:
        kfree(sgt);
err_unpin:
        mutex_unlock(&omap_obj->lock);
        omap_gem_unpin(obj);
        return ERR_PTR(ret);
}

void omap_gem_put_sg(struct drm_gem_object *obj, struct sg_table *sgt)
{
        struct omap_gem_object *omap_obj = to_omap_bo(obj);

        if (WARN_ON(omap_obj->sgt != sgt))
                return;

        omap_gem_unpin(obj);
}

#ifdef CONFIG_DRM_FBDEV_EMULATION
/*
 * Get kernel virtual address for CPU access.. this more or less only
 * exists for omap_fbdev.
 */
void *omap_gem_vaddr(struct drm_gem_object *obj)
{
        struct omap_gem_object *omap_obj = to_omap_bo(obj);
        void *vaddr;
        int ret;

        mutex_lock(&omap_obj->lock);

        if (!omap_obj->vaddr) {
                ret = omap_gem_attach_pages(obj);
                if (ret) {
                        vaddr = ERR_PTR(ret);
                        goto unlock;
                }

                omap_obj->vaddr = vmap(omap_obj->pages, obj->size >> PAGE_SHIFT,
                                VM_MAP, pgprot_writecombine(PAGE_KERNEL));
        }

        vaddr = omap_obj->vaddr;

unlock:
        mutex_unlock(&omap_obj->lock);
        return vaddr;
}
#endif

/* -----------------------------------------------------------------------------
 * Power Management
 */

#ifdef CONFIG_PM
/* re-pin objects in DMM in resume path: */
int omap_gem_resume(struct drm_device *dev)
{
        struct omap_drm_private *priv = dev->dev_private;
        struct omap_gem_object *omap_obj;
        int ret = 0;

        mutex_lock(&priv->list_lock);
        list_for_each_entry(omap_obj, &priv->obj_list, mm_list) {
                if (omap_obj->block) {
                        struct drm_gem_object *obj = &omap_obj->base;
                        u32 npages = obj->size >> PAGE_SHIFT;

                        WARN_ON(!omap_obj->pages);  /* this can't happen */
                        ret = tiler_pin(omap_obj->block,
                                        omap_obj->pages, npages,
                                        omap_obj->roll, true);
                        if (ret) {
                                dev_err(dev->dev, "could not repin: %d\n", ret);
                                goto done;
                        }
                }
        }

done:
        mutex_unlock(&priv->list_lock);
        return ret;
}
#endif

/* -----------------------------------------------------------------------------
 * DebugFS
 */

#ifdef CONFIG_DEBUG_FS
void omap_gem_describe(struct drm_gem_object *obj, struct seq_file *m)
{
        struct omap_gem_object *omap_obj = to_omap_bo(obj);
        u64 off;

        off = drm_vma_node_start(&obj->vma_node);

        mutex_lock(&omap_obj->lock);

        seq_printf(m, "%08x: %2d (%2d) %08llx %pad (%2d) %p %4d",
                        omap_obj->flags, obj->name, kref_read(&obj->refcount),
                        off, &omap_obj->dma_addr,
                        refcount_read(&omap_obj->pin_cnt),
                        omap_obj->vaddr, omap_obj->roll);

        if (omap_obj->flags & OMAP_BO_TILED_MASK) {
                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, " %zu", obj->size);
        }

        mutex_unlock(&omap_obj->lock);

        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

/* -----------------------------------------------------------------------------
 * Constructor & Destructor
 */

static void omap_gem_free_object(struct drm_gem_object *obj)
{
        struct drm_device *dev = obj->dev;
        struct omap_drm_private *priv = dev->dev_private;
        struct omap_gem_object *omap_obj = to_omap_bo(obj);

        omap_gem_evict(obj);

        mutex_lock(&priv->list_lock);
        list_del(&omap_obj->mm_list);
        mutex_unlock(&priv->list_lock);

        /*
         * We own the sole reference to the object at this point, but to keep
         * lockdep happy, we must still take the omap_obj_lock to call
         * omap_gem_detach_pages(). This should hardly make any difference as
         * there can't be any lock contention.
         */
        mutex_lock(&omap_obj->lock);

        /* The object should not be pinned. */
        WARN_ON(refcount_read(&omap_obj->pin_cnt) > 0);

        if (omap_obj->pages) {
                if (omap_obj->flags & OMAP_BO_MEM_DMABUF)
                        kfree(omap_obj->pages);
                else
                        omap_gem_detach_pages(obj);
        }

        if (omap_obj->flags & OMAP_BO_MEM_DMA_API) {
                dma_free_wc(dev->dev, obj->size, omap_obj->vaddr,
                            omap_obj->dma_addr);
        } else if (omap_obj->vaddr) {
                vunmap(omap_obj->vaddr);
        } else if (obj->import_attach) {
                drm_prime_gem_destroy(obj, omap_obj->sgt);
        }

        mutex_unlock(&omap_obj->lock);

        drm_gem_object_release(obj);

        mutex_destroy(&omap_obj->lock);

        kfree(omap_obj);
}

static bool omap_gem_validate_flags(struct drm_device *dev, u32 flags)
{
        struct omap_drm_private *priv = dev->dev_private;

        switch (flags & OMAP_BO_CACHE_MASK) {
        case OMAP_BO_CACHED:
        case OMAP_BO_WC:
        case OMAP_BO_CACHE_MASK:
                break;

        default:
                return false;
        }

        if (flags & OMAP_BO_TILED_MASK) {
                if (!priv->usergart)
                        return false;

                switch (flags & OMAP_BO_TILED_MASK) {
                case OMAP_BO_TILED_8:
                case OMAP_BO_TILED_16:
                case OMAP_BO_TILED_32:
                        break;

                default:
                        return false;
                }
        }

        return true;
}

static const struct vm_operations_struct omap_gem_vm_ops = {
        .fault = omap_gem_fault,
        .open = drm_gem_vm_open,
        .close = drm_gem_vm_close,
};

static const struct drm_gem_object_funcs omap_gem_object_funcs = {
        .free = omap_gem_free_object,
        .export = omap_gem_prime_export,
        .mmap = omap_gem_object_mmap,
        .vm_ops = &omap_gem_vm_ops,
};

/* GEM buffer object constructor */
struct drm_gem_object *omap_gem_new(struct drm_device *dev,
                union omap_gem_size gsize, u32 flags)
{
        struct omap_drm_private *priv = dev->dev_private;
        struct omap_gem_object *omap_obj;
        struct drm_gem_object *obj;
        struct address_space *mapping;
        size_t size;
        int ret;

        if (!omap_gem_validate_flags(dev, flags))
                return NULL;

        /* Validate the flags and compute the memory and cache flags. */
        if (flags & OMAP_BO_TILED_MASK) {
                /*
                 * Tiled buffers are always shmem paged backed. When they are
                 * scanned out, they are remapped into DMM/TILER.
                 */
                flags |= OMAP_BO_MEM_SHMEM;

                /*
                 * Currently don't allow cached buffers. There is some caching
                 * stuff that needs to be handled better.
                 */
                flags &= ~(OMAP_BO_CACHED|OMAP_BO_WC|OMAP_BO_UNCACHED);
                flags |= tiler_get_cpu_cache_flags();
        } else if ((flags & OMAP_BO_SCANOUT) && !priv->has_dmm) {
                /*
                 * If we don't have DMM, we must allocate scanout buffers
                 * from contiguous DMA memory.
                 */
                flags |= OMAP_BO_MEM_DMA_API;
        } else if (!(flags & OMAP_BO_MEM_DMABUF)) {
                /*
                 * All other buffers not backed by dma_buf are shmem-backed.
                 */
                flags |= OMAP_BO_MEM_SHMEM;
        }

        /* Allocate the initialize the OMAP GEM object. */
        omap_obj = kzalloc_obj(*omap_obj);
        if (!omap_obj)
                return NULL;

        obj = &omap_obj->base;
        omap_obj->flags = flags;
        mutex_init(&omap_obj->lock);

        if (flags & OMAP_BO_TILED_MASK) {
                /*
                 * For tiled buffers align dimensions to slot boundaries and
                 * calculate size based on aligned dimensions.
                 */
                tiler_align(gem2fmt(flags), &gsize.tiled.width,
                            &gsize.tiled.height);

                size = tiler_size(gem2fmt(flags), gsize.tiled.width,
                                  gsize.tiled.height);

                omap_obj->width = gsize.tiled.width;
                omap_obj->height = gsize.tiled.height;
        } else {
                size = PAGE_ALIGN(gsize.bytes);
        }

        obj->funcs = &omap_gem_object_funcs;

        /* Initialize the GEM object. */
        if (!(flags & OMAP_BO_MEM_SHMEM)) {
                drm_gem_private_object_init(dev, obj, size);
        } else {
                ret = drm_gem_object_init(dev, obj, size);
                if (ret)
                        goto err_free;

                mapping = obj->filp->f_mapping;
                mapping_set_gfp_mask(mapping, GFP_USER | __GFP_DMA32);
        }

        /* Allocate memory if needed. */
        if (flags & OMAP_BO_MEM_DMA_API) {
                omap_obj->vaddr = dma_alloc_wc(dev->dev, size,
                                               &omap_obj->dma_addr,
                                               GFP_KERNEL);
                if (!omap_obj->vaddr)
                        goto err_release;
        }

        mutex_lock(&priv->list_lock);
        list_add(&omap_obj->mm_list, &priv->obj_list);
        mutex_unlock(&priv->list_lock);

        return obj;

err_release:
        drm_gem_object_release(obj);
err_free:
        kfree(omap_obj);
        return NULL;
}

struct drm_gem_object *omap_gem_new_dmabuf(struct drm_device *dev, size_t size,
                                           struct sg_table *sgt)
{
        struct omap_drm_private *priv = dev->dev_private;
        struct omap_gem_object *omap_obj;
        struct drm_gem_object *obj;
        union omap_gem_size gsize;

        /* Without a DMM only physically contiguous buffers can be supported. */
        if (!omap_gem_sgt_is_contiguous(sgt, size) && !priv->has_dmm)
                return ERR_PTR(-EINVAL);

        gsize.bytes = PAGE_ALIGN(size);
        obj = omap_gem_new(dev, gsize, OMAP_BO_MEM_DMABUF | OMAP_BO_WC);
        if (!obj)
                return ERR_PTR(-ENOMEM);

        omap_obj = to_omap_bo(obj);

        omap_obj->sgt = sgt;

        if (omap_gem_sgt_is_contiguous(sgt, size)) {
                omap_obj->dma_addr = sg_dma_address(sgt->sgl);
        } else {
                /* Create pages list from sgt */
                struct page **pages;
                unsigned int npages;
                unsigned int ret;

                npages = DIV_ROUND_UP(size, PAGE_SIZE);
                pages = kzalloc_objs(*pages, npages);
                if (!pages) {
                        omap_gem_free_object(obj);
                        return ERR_PTR(-ENOMEM);
                }

                omap_obj->pages = pages;
                ret = drm_prime_sg_to_page_array(sgt, pages, npages);
                if (ret) {
                        omap_gem_free_object(obj);
                        return ERR_PTR(-ENOMEM);
                }
        }

        return 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, u32 flags, u32 *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) {
                omap_gem_free_object(obj);
                return ret;
        }

        /* drop reference from allocate - handle holds it now */
        drm_gem_object_put(obj);

        return 0;
}

/* -----------------------------------------------------------------------------
 * 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;
        struct omap_drm_usergart *usergart;
        const enum tiler_fmt fmts[] = {
                        TILFMT_8BIT, TILFMT_16BIT, TILFMT_32BIT
        };
        int i, j;

        if (!dmm_is_available()) {
                /* 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_objs(*usergart, 3);
        if (!usergart)
                return;

        /* reserve 4k aligned/wide regions for userspace mappings: */
        for (i = 0; i < ARRAY_SIZE(fmts); i++) {
                u16 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 omap_drm_usergart_entry *entry;
                        struct tiler_block *block;

                        entry = &usergart[i].entry[j];
                        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->dma_addr = tiler_ssptr(block);
                        entry->block = block;

                        DBG("%d:%d: %dx%d: dma_addr=%pad stride=%d", i, j, w, h,
                                        &entry->dma_addr,
                                        usergart[i].stride_pfn << PAGE_SHIFT);
                }
        }

        priv->usergart = usergart;
        priv->has_dmm = true;
}

void omap_gem_deinit(struct drm_device *dev)
{
        struct omap_drm_private *priv = dev->dev_private;

        /* I believe we can rely on there being no more outstanding GEM
         * objects which could depend on usergart/dmm at this point.
         */
        kfree(priv->usergart);
}