/*
 * Copyright 2011 Red Hat, Inc.
 * Copyright © 2014 The Chromium OS Authors
 *
 * 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
 * on the rights to use, copy, modify, merge, publish, distribute, sub
 * license, and/or sell copies of the Software, and to permit persons to whom
 * them 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 MERCHANTIBILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS 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:
 *      Adam Jackson <ajax@redhat.com>
 *      Ben Widawsky <ben@bwidawsk.net>
 */

/**
 * This is vgem, a (non-hardware-backed) GEM service.  This is used by Mesa's
 * software renderer and the X server for efficient buffer sharing.
 */

#include <linux/module.h>
#include <linux/ramfs.h>
#include <linux/shmem_fs.h>
#include <linux/dma-buf.h>
#include "vgem_drv.h"

#define DRIVER_NAME     "vgem"
#define DRIVER_DESC     "Virtual GEM provider"
#define DRIVER_DATE     "20120112"
#define DRIVER_MAJOR    1
#define DRIVER_MINOR    0

void vgem_gem_put_pages(struct drm_vgem_gem_object *obj)
{
        drm_gem_put_pages(&obj->base, obj->pages, false, false);
        obj->pages = NULL;
}

static void vgem_gem_free_object(struct drm_gem_object *obj)
{
        struct drm_vgem_gem_object *vgem_obj = to_vgem_bo(obj);

        drm_gem_free_mmap_offset(obj);

        if (vgem_obj->use_dma_buf && obj->dma_buf) {
                dma_buf_put(obj->dma_buf);
                obj->dma_buf = NULL;
        }

        drm_gem_object_release(obj);

        if (vgem_obj->pages)
                vgem_gem_put_pages(vgem_obj);

        vgem_obj->pages = NULL;

        kfree(vgem_obj);
}

int vgem_gem_get_pages(struct drm_vgem_gem_object *obj)
{
        struct page **pages;

        if (obj->pages || obj->use_dma_buf)
                return 0;

        pages = drm_gem_get_pages(&obj->base);
        if (IS_ERR(pages)) {
                return PTR_ERR(pages);
        }

        obj->pages = pages;

        return 0;
}

static int vgem_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
        struct drm_vgem_gem_object *obj = vma->vm_private_data;
        struct drm_device *dev = obj->base.dev;
        loff_t num_pages;
        pgoff_t page_offset;
        int ret;

        /* We don't use vmf->pgoff since that has the fake offset */
        page_offset = ((unsigned long)vmf->virtual_address - vma->vm_start) >>
                PAGE_SHIFT;

        num_pages = DIV_ROUND_UP(obj->base.size, PAGE_SIZE);

        if (page_offset > num_pages)
                return VM_FAULT_SIGBUS;

        mutex_lock(&dev->struct_mutex);

        ret = vm_insert_page(vma, (unsigned long)vmf->virtual_address,
                             obj->pages[page_offset]);

        mutex_unlock(&dev->struct_mutex);
        switch (ret) {
        case 0:
                return VM_FAULT_NOPAGE;
        case -ENOMEM:
                return VM_FAULT_OOM;
        case -EBUSY:
                return VM_FAULT_RETRY;
        case -EFAULT:
        case -EINVAL:
                return VM_FAULT_SIGBUS;
        default:
                WARN_ON(1);
                return VM_FAULT_SIGBUS;
        }
}

static const struct vm_operations_struct vgem_gem_vm_ops = {
        .fault = vgem_gem_fault,
        .open = drm_gem_vm_open,
        .close = drm_gem_vm_close,
};

/* ioctls */

static struct drm_gem_object *vgem_gem_create(struct drm_device *dev,
                                              struct drm_file *file,
                                              unsigned int *handle,
                                              unsigned long size)
{
        struct drm_vgem_gem_object *obj;
        struct drm_gem_object *gem_object;
        int err;

        size = roundup(size, PAGE_SIZE);

        obj = kzalloc(sizeof(*obj), GFP_KERNEL);
        if (!obj)
                return ERR_PTR(-ENOMEM);

        gem_object = &obj->base;

        err = drm_gem_object_init(dev, gem_object, size);
        if (err)
                goto out;

        err = drm_gem_handle_create(file, gem_object, handle);
        if (err)
                goto handle_out;

        drm_gem_object_unreference_unlocked(gem_object);

        return gem_object;

handle_out:
        drm_gem_object_release(gem_object);
out:
        kfree(obj);
        return ERR_PTR(err);
}

static int vgem_gem_dumb_create(struct drm_file *file, struct drm_device *dev,
                                struct drm_mode_create_dumb *args)
{
        struct drm_gem_object *gem_object;
        uint64_t size;
        uint64_t pitch = args->width * DIV_ROUND_UP(args->bpp, 8);

        size = args->height * pitch;
        if (size == 0)
                return -EINVAL;

        gem_object = vgem_gem_create(dev, file, &args->handle, size);

        if (IS_ERR(gem_object)) {
                DRM_DEBUG_DRIVER("object creation failed\n");
                return PTR_ERR(gem_object);
        }

        args->size = gem_object->size;
        args->pitch = pitch;

        DRM_DEBUG_DRIVER("Created object of size %lld\n", size);

        return 0;
}

int vgem_gem_dumb_map(struct drm_file *file, struct drm_device *dev,
                      uint32_t handle, uint64_t *offset)
{
        int ret = 0;
        struct drm_gem_object *obj;

        mutex_lock(&dev->struct_mutex);
        obj = drm_gem_object_lookup(dev, file, handle);
        if (!obj) {
                ret = -ENOENT;
                goto unlock;
        }

        if (!drm_vma_node_has_offset(&obj->vma_node)) {
                ret = drm_gem_create_mmap_offset(obj);
                if (ret)
                        goto unref;
        }

        BUG_ON(!obj->filp);

        obj->filp->private_data = obj;

        ret = vgem_gem_get_pages(to_vgem_bo(obj));
        if (ret)
                goto fail_get_pages;

        *offset = drm_vma_node_offset_addr(&obj->vma_node);

        goto unref;

fail_get_pages:
        drm_gem_free_mmap_offset(obj);
unref:
        drm_gem_object_unreference(obj);
unlock:
        mutex_unlock(&dev->struct_mutex);
        return ret;
}

static struct drm_ioctl_desc vgem_ioctls[] = {
};

static const struct file_operations vgem_driver_fops = {
        .owner          = THIS_MODULE,
        .open           = drm_open,
        .mmap           = drm_gem_mmap,
        .poll           = drm_poll,
        .read           = drm_read,
        .unlocked_ioctl = drm_ioctl,
        .release        = drm_release,
};

static struct drm_driver vgem_driver = {
        .driver_features                = DRIVER_GEM,
        .gem_free_object                = vgem_gem_free_object,
        .gem_vm_ops                     = &vgem_gem_vm_ops,
        .ioctls                         = vgem_ioctls,
        .fops                           = &vgem_driver_fops,
        .dumb_create                    = vgem_gem_dumb_create,
        .dumb_map_offset                = vgem_gem_dumb_map,
        .name   = DRIVER_NAME,
        .desc   = DRIVER_DESC,
        .date   = DRIVER_DATE,
        .major  = DRIVER_MAJOR,
        .minor  = DRIVER_MINOR,
};

struct drm_device *vgem_device;

static int __init vgem_init(void)
{
        int ret;

        vgem_device = drm_dev_alloc(&vgem_driver, NULL);
        if (!vgem_device) {
                ret = -ENOMEM;
                goto out;
        }

        drm_dev_set_unique(vgem_device, "vgem");

        ret  = drm_dev_register(vgem_device, 0);

        if (ret)
                goto out_unref;

        return 0;

out_unref:
        drm_dev_unref(vgem_device);
out:
        return ret;
}

static void __exit vgem_exit(void)
{
        drm_dev_unregister(vgem_device);
        drm_dev_unref(vgem_device);
}

module_init(vgem_init);
module_exit(vgem_exit);

MODULE_AUTHOR("Red Hat, Inc.");
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL and additional rights");