omap_gem.c

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/*
 * drivers/staging/omapdrm/omap_gem.c
 *
 * Copyright (C) 2011 Texas Instruments
 * Author: Rob Clark <[email protected]>
 *
 * 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;

    uint16_t width, height;

    uint32_t roll;

    dma_addr_t paddr;

    uint32_t paddr_cnt;

    struct tiler_block *block;

    struct page **pages;

    dma_addr_t *addrs;

    void *vaddr;

    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;
}

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);

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;
}

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;
}

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;
}

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;
}

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;
    }
}

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;
}


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);
}

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);
}

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);
}