/**************************************************************************
 *
 * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
 * All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sub license, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial portions
 * of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
 * USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 **************************************************************************/
/*
 * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
 */

#include <ttm/ttm_module.h>
#include <ttm/ttm_bo_driver.h>
#include <ttm/ttm_placement.h>
#include <linux/mm.h>
#include <linux/rbtree.h>
#include <linux/module.h>
#include <linux/uaccess.h>

#define TTM_BO_VM_NUM_PREFAULT 16

static struct ttm_buffer_object *ttm_bo_vm_lookup_rb(struct ttm_bo_device *bdev,
                                                     unsigned long page_start,
                                                     unsigned long num_pages)
{
        struct rb_node *cur = bdev->addr_space_rb.rb_node;
        unsigned long cur_offset;
        struct ttm_buffer_object *bo;
        struct ttm_buffer_object *best_bo = NULL;

        while (likely(cur != NULL)) {
                bo = rb_entry(cur, struct ttm_buffer_object, vm_rb);
                cur_offset = bo->vm_node->start;
                if (page_start >= cur_offset) {
                        cur = cur->rb_right;
                        best_bo = bo;
                        if (page_start == cur_offset)
                                break;
                } else
                        cur = cur->rb_left;
        }

        if (unlikely(best_bo == NULL))
                return NULL;

        if (unlikely((best_bo->vm_node->start + best_bo->num_pages) <
                     (page_start + num_pages)))
                return NULL;

        return best_bo;
}

static int ttm_bo_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
        struct ttm_buffer_object *bo = (struct ttm_buffer_object *)
            vma->vm_private_data;
        struct ttm_bo_device *bdev = bo->bdev;
        unsigned long bus_base;
        unsigned long bus_offset;
        unsigned long bus_size;
        unsigned long page_offset;
        unsigned long page_last;
        unsigned long pfn;
        struct ttm_tt *ttm = NULL;
        struct page *page;
        int ret;
        int i;
        bool is_iomem;
        unsigned long address = (unsigned long)vmf->virtual_address;
        int retval = VM_FAULT_NOPAGE;

        /*
         * Work around locking order reversal in fault / nopfn
         * between mmap_sem and bo_reserve: Perform a trylock operation
         * for reserve, and if it fails, retry the fault after scheduling.
         */

        ret = ttm_bo_reserve(bo, true, true, false, 0);
        if (unlikely(ret != 0)) {
                if (ret == -EBUSY)
                        set_need_resched();
                return VM_FAULT_NOPAGE;
        }

        if (bdev->driver->fault_reserve_notify)
                bdev->driver->fault_reserve_notify(bo);

        /*
         * Wait for buffer data in transit, due to a pipelined
         * move.
         */

        spin_lock(&bo->lock);
        if (test_bit(TTM_BO_PRIV_FLAG_MOVING, &bo->priv_flags)) {
                ret = ttm_bo_wait(bo, false, true, false);
                spin_unlock(&bo->lock);
                if (unlikely(ret != 0)) {
                        retval = (ret != -ERESTART) ?
                            VM_FAULT_SIGBUS : VM_FAULT_NOPAGE;
                        goto out_unlock;
                }
        } else
                spin_unlock(&bo->lock);


        ret = ttm_bo_pci_offset(bdev, &bo->mem, &bus_base, &bus_offset,
                                &bus_size);
        if (unlikely(ret != 0)) {
                retval = VM_FAULT_SIGBUS;
                goto out_unlock;
        }

        is_iomem = (bus_size != 0);

        page_offset = ((address - vma->vm_start) >> PAGE_SHIFT) +
            bo->vm_node->start - vma->vm_pgoff;
        page_last = ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) +
            bo->vm_node->start - vma->vm_pgoff;

        if (unlikely(page_offset >= bo->num_pages)) {
                retval = VM_FAULT_SIGBUS;
                goto out_unlock;
        }

        /*
         * Strictly, we're not allowed to modify vma->vm_page_prot here,
         * since the mmap_sem is only held in read mode. However, we
         * modify only the caching bits of vma->vm_page_prot and
         * consider those bits protected by
         * the bo->mutex, as we should be the only writers.
         * There shouldn't really be any readers of these bits except
         * within vm_insert_mixed()? fork?
         *
         * TODO: Add a list of vmas to the bo, and change the
         * vma->vm_page_prot when the object changes caching policy, with
         * the correct locks held.
         */

        if (is_iomem) {
                vma->vm_page_prot = ttm_io_prot(bo->mem.placement,
                                                vma->vm_page_prot);
        } else {
                ttm = bo->ttm;
                vma->vm_page_prot = (bo->mem.placement & TTM_PL_FLAG_CACHED) ?
                    vm_get_page_prot(vma->vm_flags) :
                    ttm_io_prot(bo->mem.placement, vma->vm_page_prot);
        }

        /*
         * Speculatively prefault a number of pages. Only error on
         * first page.
         */

        for (i = 0; i < TTM_BO_VM_NUM_PREFAULT; ++i) {

                if (is_iomem)
                        pfn = ((bus_base + bus_offset) >> PAGE_SHIFT) +
                            page_offset;
                else {
                        page = ttm_tt_get_page(ttm, page_offset);
                        if (unlikely(!page && i == 0)) {
                                retval = VM_FAULT_OOM;
                                goto out_unlock;
                        } else if (unlikely(!page)) {
                                break;
                        }
                        pfn = page_to_pfn(page);
                }

                ret = vm_insert_mixed(vma, address, pfn);
                /*
                 * Somebody beat us to this PTE or prefaulting to
                 * an already populated PTE, or prefaulting error.
                 */

                if (unlikely((ret == -EBUSY) || (ret != 0 && i > 0)))
                        break;
                else if (unlikely(ret != 0)) {
                        retval =
                            (ret == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS;
                        goto out_unlock;

                }

                address += PAGE_SIZE;
                if (unlikely(++page_offset >= page_last))
                        break;
        }

out_unlock:
        ttm_bo_unreserve(bo);
        return retval;
}

static void ttm_bo_vm_open(struct vm_area_struct *vma)
{
        struct ttm_buffer_object *bo =
            (struct ttm_buffer_object *)vma->vm_private_data;

        (void)ttm_bo_reference(bo);
}

static void ttm_bo_vm_close(struct vm_area_struct *vma)
{
        struct ttm_buffer_object *bo =
            (struct ttm_buffer_object *)vma->vm_private_data;

        ttm_bo_unref(&bo);
        vma->vm_private_data = NULL;
}

static const struct vm_operations_struct ttm_bo_vm_ops = {
        .fault = ttm_bo_vm_fault,
        .open = ttm_bo_vm_open,
        .close = ttm_bo_vm_close
};

int ttm_bo_mmap(struct file *filp, struct vm_area_struct *vma,
                struct ttm_bo_device *bdev)
{
        struct ttm_bo_driver *driver;
        struct ttm_buffer_object *bo;
        int ret;

        read_lock(&bdev->vm_lock);
        bo = ttm_bo_vm_lookup_rb(bdev, vma->vm_pgoff,
                                 (vma->vm_end - vma->vm_start) >> PAGE_SHIFT);
        if (likely(bo != NULL))
                ttm_bo_reference(bo);
        read_unlock(&bdev->vm_lock);

        if (unlikely(bo == NULL)) {
                printk(KERN_ERR TTM_PFX
                       "Could not find buffer object to map.\n");
                return -EINVAL;
        }

        driver = bo->bdev->driver;
        if (unlikely(!driver->verify_access)) {
                ret = -EPERM;
                goto out_unref;
        }
        ret = driver->verify_access(bo, filp);
        if (unlikely(ret != 0))
                goto out_unref;

        vma->vm_ops = &ttm_bo_vm_ops;

        /*
         * Note: We're transferring the bo reference to
         * vma->vm_private_data here.
         */

        vma->vm_private_data = bo;
        vma->vm_flags |= VM_RESERVED | VM_IO | VM_MIXEDMAP | VM_DONTEXPAND;
        return 0;
out_unref:
        ttm_bo_unref(&bo);
        return ret;
}
EXPORT_SYMBOL(ttm_bo_mmap);

int ttm_fbdev_mmap(struct vm_area_struct *vma, struct ttm_buffer_object *bo)
{
        if (vma->vm_pgoff != 0)
                return -EACCES;

        vma->vm_ops = &ttm_bo_vm_ops;
        vma->vm_private_data = ttm_bo_reference(bo);
        vma->vm_flags |= VM_RESERVED | VM_IO | VM_MIXEDMAP | VM_DONTEXPAND;
        return 0;
}
EXPORT_SYMBOL(ttm_fbdev_mmap);


ssize_t ttm_bo_io(struct ttm_bo_device *bdev, struct file *filp,
                  const char __user *wbuf, char __user *rbuf, size_t count,
                  loff_t *f_pos, bool write)
{
        struct ttm_buffer_object *bo;
        struct ttm_bo_driver *driver;
        struct ttm_bo_kmap_obj map;
        unsigned long dev_offset = (*f_pos >> PAGE_SHIFT);
        unsigned long kmap_offset;
        unsigned long kmap_end;
        unsigned long kmap_num;
        size_t io_size;
        unsigned int page_offset;
        char *virtual;
        int ret;
        bool no_wait = false;
        bool dummy;

        read_lock(&bdev->vm_lock);
        bo = ttm_bo_vm_lookup_rb(bdev, dev_offset, 1);
        if (likely(bo != NULL))
                ttm_bo_reference(bo);
        read_unlock(&bdev->vm_lock);

        if (unlikely(bo == NULL))
                return -EFAULT;

        driver = bo->bdev->driver;
        if (unlikely(driver->verify_access)) {
                ret = -EPERM;
                goto out_unref;
        }

        ret = driver->verify_access(bo, filp);
        if (unlikely(ret != 0))
                goto out_unref;

        kmap_offset = dev_offset - bo->vm_node->start;
        if (unlikely(kmap_offset >= bo->num_pages)) {
                ret = -EFBIG;
                goto out_unref;
        }

        page_offset = *f_pos & ~PAGE_MASK;
        io_size = bo->num_pages - kmap_offset;
        io_size = (io_size << PAGE_SHIFT) - page_offset;
        if (count < io_size)
                io_size = count;

        kmap_end = (*f_pos + count - 1) >> PAGE_SHIFT;
        kmap_num = kmap_end - kmap_offset + 1;

        ret = ttm_bo_reserve(bo, true, no_wait, false, 0);

        switch (ret) {
        case 0:
                break;
        case -ERESTART:
                ret = -EINTR;
                goto out_unref;
        case -EBUSY:
                ret = -EAGAIN;
                goto out_unref;
        default:
                goto out_unref;
        }

        ret = ttm_bo_kmap(bo, kmap_offset, kmap_num, &map);
        if (unlikely(ret != 0)) {
                ttm_bo_unreserve(bo);
                goto out_unref;
        }

        virtual = ttm_kmap_obj_virtual(&map, &dummy);
        virtual += page_offset;

        if (write)
                ret = copy_from_user(virtual, wbuf, io_size);
        else
                ret = copy_to_user(rbuf, virtual, io_size);

        ttm_bo_kunmap(&map);
        ttm_bo_unreserve(bo);
        ttm_bo_unref(&bo);

        if (unlikely(ret != 0))
                return -EFBIG;

        *f_pos += io_size;

        return io_size;
out_unref:
        ttm_bo_unref(&bo);
        return ret;
}

ssize_t ttm_bo_fbdev_io(struct ttm_buffer_object *bo, const char __user *wbuf,
                        char __user *rbuf, size_t count, loff_t *f_pos,
                        bool write)
{
        struct ttm_bo_kmap_obj map;
        unsigned long kmap_offset;
        unsigned long kmap_end;
        unsigned long kmap_num;
        size_t io_size;
        unsigned int page_offset;
        char *virtual;
        int ret;
        bool no_wait = false;
        bool dummy;

        kmap_offset = (*f_pos >> PAGE_SHIFT);
        if (unlikely(kmap_offset >= bo->num_pages))
                return -EFBIG;

        page_offset = *f_pos & ~PAGE_MASK;
        io_size = bo->num_pages - kmap_offset;
        io_size = (io_size << PAGE_SHIFT) - page_offset;
        if (count < io_size)
                io_size = count;

        kmap_end = (*f_pos + count - 1) >> PAGE_SHIFT;
        kmap_num = kmap_end - kmap_offset + 1;

        ret = ttm_bo_reserve(bo, true, no_wait, false, 0);

        switch (ret) {
        case 0:
                break;
        case -ERESTART:
                return -EINTR;
        case -EBUSY:
                return -EAGAIN;
        default:
                return ret;
        }

        ret = ttm_bo_kmap(bo, kmap_offset, kmap_num, &map);
        if (unlikely(ret != 0)) {
                ttm_bo_unreserve(bo);
                return ret;
        }

        virtual = ttm_kmap_obj_virtual(&map, &dummy);
        virtual += page_offset;

        if (write)
                ret = copy_from_user(virtual, wbuf, io_size);
        else
                ret = copy_to_user(rbuf, virtual, io_size);

        ttm_bo_kunmap(&map);
        ttm_bo_unreserve(bo);
        ttm_bo_unref(&bo);

        if (unlikely(ret != 0))
                return ret;

        *f_pos += io_size;

        return io_size;
}