/**************************************************************************
 *
 * 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>
 */
/*
 * Copyright (c) 2013 The FreeBSD Foundation
 * All rights reserved.
 *
 * Portions of this software were developed by Konstantin Belousov
 * <kib@FreeBSD.org> under sponsorship from the FreeBSD Foundation.
 */

#include <sys/param.h>
#include <sys/pctrie.h>
#include "opt_vm.h"

#include <dev/drm2/drmP.h>
#include <dev/drm2/ttm/ttm_module.h>
#include <dev/drm2/ttm/ttm_bo_driver.h>
#include <dev/drm2/ttm/ttm_placement.h>

#include <vm/vm.h>
#include <vm/vm_page.h>
#include <vm/vm_pageout.h>
#include <vm/vm_radix.h>

#define TTM_BO_VM_NUM_PREFAULT 16

RB_GENERATE(ttm_bo_device_buffer_objects, ttm_buffer_object, vm_rb,
    ttm_bo_cmp_rb_tree_items);

int
ttm_bo_cmp_rb_tree_items(struct ttm_buffer_object *a,
    struct ttm_buffer_object *b)
{

        if (a->vm_node->start < b->vm_node->start) {
                return (-1);
        } else if (a->vm_node->start > b->vm_node->start) {
                return (1);
        } else {
                return (0);
        }
}

static struct ttm_buffer_object *ttm_bo_vm_lookup_rb(struct ttm_bo_device *bdev,
                                                     unsigned long page_start,
                                                     unsigned long num_pages)
{
        unsigned long cur_offset;
        struct ttm_buffer_object *bo;
        struct ttm_buffer_object *best_bo = NULL;

        bo = RB_ROOT(&bdev->addr_space_rb);
        while (bo != NULL) {
                cur_offset = bo->vm_node->start;
                if (page_start >= cur_offset) {
                        best_bo = bo;
                        if (page_start == cur_offset)
                                break;
                        bo = RB_RIGHT(bo, vm_rb);
                } else
                        bo = RB_LEFT(bo, vm_rb);
        }

        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(vm_object_t vm_obj, vm_ooffset_t offset,
    int prot, vm_page_t *mres)
{
        struct pctrie_iter pages;
        struct ttm_buffer_object *bo = vm_obj->handle;
        struct ttm_bo_device *bdev = bo->bdev;
        struct ttm_tt *ttm = NULL;
        vm_page_t m, m1;
        int ret;
        int retval = VM_PAGER_OK;
        struct ttm_mem_type_manager *man =
                &bdev->man[bo->mem.mem_type];

        vm_object_pip_add(vm_obj, 1);
        if (*mres != NULL) {
                (void)vm_page_remove(*mres);
        }
        vm_page_iter_init(&pages, vm_obj);
retry:
        VM_OBJECT_WUNLOCK(vm_obj);
        m = NULL;

reserve:
        ret = ttm_bo_reserve(bo, false, false, false, 0);
        if (unlikely(ret != 0)) {
                if (ret == -EBUSY) {
                        kern_yield(PRI_USER);
                        goto reserve;
                }
        }

        if (bdev->driver->fault_reserve_notify) {
                ret = bdev->driver->fault_reserve_notify(bo);
                switch (ret) {
                case 0:
                        break;
                case -EBUSY:
                case -ERESTARTSYS:
                case -EINTR:
                        kern_yield(PRI_USER);
                        goto reserve;
                default:
                        retval = VM_PAGER_ERROR;
                        goto out_unlock;
                }
        }

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

        mtx_lock(&bdev->fence_lock);
        if (test_bit(TTM_BO_PRIV_FLAG_MOVING, &bo->priv_flags)) {
                /*
                 * Here, the behavior differs between Linux and FreeBSD.
                 *
                 * On Linux, the wait is interruptible (3rd argument to
                 * ttm_bo_wait). There must be some mechanism to resume
                 * page fault handling, once the signal is processed.
                 *
                 * On FreeBSD, the wait is uninteruptible. This is not a
                 * problem as we can't end up with an unkillable process
                 * here, because the wait will eventually time out.
                 *
                 * An example of this situation is the Xorg process
                 * which uses SIGALRM internally. The signal could
                 * interrupt the wait, causing the page fault to fail
                 * and the process to receive SIGSEGV.
                 */
                ret = ttm_bo_wait(bo, false, false, false);
                mtx_unlock(&bdev->fence_lock);
                if (unlikely(ret != 0)) {
                        retval = VM_PAGER_ERROR;
                        goto out_unlock;
                }
        } else
                mtx_unlock(&bdev->fence_lock);

        ret = ttm_mem_io_lock(man, true);
        if (unlikely(ret != 0)) {
                retval = VM_PAGER_ERROR;
                goto out_unlock;
        }
        ret = ttm_mem_io_reserve_vm(bo);
        if (unlikely(ret != 0)) {
                retval = VM_PAGER_ERROR;
                goto out_io_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 (!bo->mem.bus.is_iomem) {
                /* Allocate all page at once, most common usage */
                ttm = bo->ttm;
                if (ttm->bdev->driver->ttm_tt_populate(ttm)) {
                        retval = VM_PAGER_ERROR;
                        goto out_io_unlock;
                }
        }

        if (bo->mem.bus.is_iomem) {
                m = PHYS_TO_VM_PAGE(bo->mem.bus.base + bo->mem.bus.offset +
                    offset);
                KASSERT((m->flags & PG_FICTITIOUS) != 0,
                    ("physical address %#jx not fictitious",
                    (uintmax_t)(bo->mem.bus.base + bo->mem.bus.offset
                    + offset)));
                pmap_page_set_memattr(m, ttm_io_prot(bo->mem.placement));
        } else {
                ttm = bo->ttm;
                m = ttm->pages[OFF_TO_IDX(offset)];
                if (unlikely(!m)) {
                        retval = VM_PAGER_ERROR;
                        goto out_io_unlock;
                }
                pmap_page_set_memattr(m,
                    (bo->mem.placement & TTM_PL_FLAG_CACHED) ?
                    VM_MEMATTR_WRITE_BACK : ttm_io_prot(bo->mem.placement));
        }

        VM_OBJECT_WLOCK(vm_obj);
        if (vm_page_busy_acquire(m, VM_ALLOC_WAITFAIL) == 0) {
                ttm_mem_io_unlock(man);
                ttm_bo_unreserve(bo);
                goto retry;
        }
        pctrie_iter_reset(&pages);
        m1 = vm_radix_iter_lookup(&pages, OFF_TO_IDX(offset));
        /* XXX This looks like it should just be vm_page_replace? */
        if (m1 == NULL) {
                if (vm_page_iter_insert(
                    m, vm_obj, OFF_TO_IDX(offset), &pages) != 0) {
                        vm_page_xunbusy(m);
                        VM_OBJECT_WUNLOCK(vm_obj);
                        vm_wait(vm_obj);
                        VM_OBJECT_WLOCK(vm_obj);
                        ttm_mem_io_unlock(man);
                        ttm_bo_unreserve(bo);
                        goto retry;
                }
        } else {
                KASSERT(m == m1,
                    ("inconsistent insert bo %p m %p m1 %p offset %jx",
                    bo, m, m1, (uintmax_t)offset));
        }
        vm_page_valid(m);
        if (*mres != NULL) {
                KASSERT(*mres != m, ("losing %p %p", *mres, m));
                vm_page_xunbusy(*mres);
                vm_page_free(*mres);
        }
        *mres = m;

out_io_unlock1:
        ttm_mem_io_unlock(man);
out_unlock1:
        ttm_bo_unreserve(bo);
        vm_object_pip_wakeup(vm_obj);
        return (retval);

out_io_unlock:
        VM_OBJECT_WLOCK(vm_obj);
        goto out_io_unlock1;

out_unlock:
        VM_OBJECT_WLOCK(vm_obj);
        goto out_unlock1;
}

static int
ttm_bo_vm_ctor(void *handle, vm_ooffset_t size, vm_prot_t prot,
    vm_ooffset_t foff, struct ucred *cred, u_short *color)
{

        /*
         * On Linux, a reference to the buffer object is acquired here.
         * The reason is that this function is not called when the
         * mmap() is initialized, but only when a process forks for
         * instance. Therefore on Linux, the reference on the bo is
         * acquired either in ttm_bo_mmap() or ttm_bo_vm_open(). It's
         * then released in ttm_bo_vm_close().
         *
         * Here, this function is called during mmap() initialization.
         * Thus, the reference acquired in ttm_bo_mmap_single() is
         * sufficient.
         */

        *color = 0;
        return (0);
}

static void
ttm_bo_vm_dtor(void *handle)
{
        struct ttm_buffer_object *bo = handle;

        ttm_bo_unref(&bo);
}

static struct cdev_pager_ops ttm_pager_ops = {
        .cdev_pg_fault = ttm_bo_vm_fault,
        .cdev_pg_ctor = ttm_bo_vm_ctor,
        .cdev_pg_dtor = ttm_bo_vm_dtor
};

int
ttm_bo_mmap_single(struct ttm_bo_device *bdev, vm_ooffset_t *offset, vm_size_t size,
    struct vm_object **obj_res, int nprot)
{
        struct ttm_bo_driver *driver;
        struct ttm_buffer_object *bo;
        struct vm_object *vm_obj;
        int ret;

        rw_wlock(&bdev->vm_lock);
        bo = ttm_bo_vm_lookup_rb(bdev, OFF_TO_IDX(*offset), OFF_TO_IDX(size));
        if (likely(bo != NULL))
                refcount_acquire(&bo->kref);
        rw_wunlock(&bdev->vm_lock);

        if (unlikely(bo == NULL)) {
                printf("[TTM] 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);
        if (unlikely(ret != 0))
                goto out_unref;

        vm_obj = cdev_pager_allocate(bo, OBJT_MGTDEVICE, &ttm_pager_ops,
            size, nprot, 0, curthread->td_ucred);
        if (vm_obj == NULL) {
                ret = -EINVAL;
                goto out_unref;
        }
        /*
         * Note: We're transferring the bo reference to vm_obj->handle here.
         */
        *offset = 0;
        *obj_res = vm_obj;
        return 0;
out_unref:
        ttm_bo_unref(&bo);
        return ret;
}

void
ttm_bo_release_mmap(struct ttm_buffer_object *bo)
{
        vm_object_t vm_obj;

        vm_obj = cdev_pager_lookup(bo);
        if (vm_obj != NULL) {
                cdev_mgtdev_pager_free_pages(vm_obj);
                vm_object_deallocate(vm_obj);
        }
}

#if 0
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_IO | VM_MIXEDMAP | VM_DONTEXPAND;
        return 0;
}

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 -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 -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;
}
#endif