/*
 *  psb GEM interface
 *
 * Copyright (c) 2011, Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope 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, write to the Free Software Foundation, Inc.,
 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Authors: Alan Cox
 *
 * TODO:
 *      -       we don't actually put GEM objects into the GART yet
 *      -       we need to work out if the MMU is relevant as well (eg for
 *              accelerated operations on a GEM object)
 *      -       cache coherency
 *
 * ie this is just an initial framework to get us going.
 */

#include <drm/drmP.h>
#include <drm/drm.h>
#include "psb_drm.h"
#include "psb_drv.h"

int psb_gem_init_object(struct drm_gem_object *obj)
{
        return -EINVAL;
}

void psb_gem_free_object(struct drm_gem_object *obj)
{
        struct gtt_range *gtt = container_of(obj, struct gtt_range, gem);
        psb_gtt_free_range(obj->dev, gtt);
        if (obj->map_list.map) {
                /* Do things GEM should do for us */
                struct drm_gem_mm *mm = obj->dev->mm_private;
                struct drm_map_list *list = &obj->map_list;
                drm_ht_remove_item(&mm->offset_hash, &list->hash);
                drm_mm_put_block(list->file_offset_node);
                kfree(list->map);
                list->map = NULL;
        }
        drm_gem_object_release(obj);
}

int psb_gem_get_aperture(struct drm_device *dev, void *data,
                                struct drm_file *file)
{
        return -EINVAL;
}

/**
 *      psb_gem_create_mmap_offset      -       invent an mmap offset
 *      @obj: our object
 *
 *      This is basically doing by hand a pile of ugly crap which should
 *      be done automatically by the GEM library code but isn't
 */
static int psb_gem_create_mmap_offset(struct drm_gem_object *obj)
{
        struct drm_device *dev = obj->dev;
        struct drm_gem_mm *mm = dev->mm_private;
        struct drm_map_list *list;
        struct drm_local_map *map;
        int ret;

        list = &obj->map_list;
        list->map = kzalloc(sizeof(struct drm_map_list), GFP_KERNEL);
        if (list->map == NULL)
                return -ENOMEM;
        map = list->map;
        map->type = _DRM_GEM;
        map->size = obj->size;
        map->handle =obj;

        list->file_offset_node = drm_mm_search_free(&mm->offset_manager,
                                        obj->size / PAGE_SIZE, 0, 0);
        if (!list->file_offset_node) {
                DRM_ERROR("failed to allocate offset for bo %d\n", obj->name);
                ret = -ENOSPC;
                goto free_it;
        }
        list->file_offset_node = drm_mm_get_block(list->file_offset_node,
                                        obj->size / PAGE_SIZE, 0);
        if (!list->file_offset_node) {
                ret = -ENOMEM;
                goto free_it;
        }
        list->hash.key = list->file_offset_node->start;
        ret = drm_ht_insert_item(&mm->offset_hash, &list->hash);
        if (ret) {
                DRM_ERROR("failed to add to map hash\n");
                goto free_mm;
        }
        return 0;

free_mm:
        drm_mm_put_block(list->file_offset_node);
free_it:
        kfree(list->map);
        list->map = NULL;
        return ret;
}

/**
 *      psb_gem_dumb_map_gtt    -       buffer mapping for dumb interface
 *      @file: our drm client file
 *      @dev: drm device
 *      @handle: GEM handle to the object (from dumb_create)
 *
 *      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 psb_gem_dumb_map_gtt(struct drm_file *file, struct drm_device *dev,
                         uint32_t handle, uint64_t *offset)
{
        int ret = 0;
        struct drm_gem_object *obj;

        if (!(dev->driver->driver_features & DRIVER_GEM))
                return -ENODEV;
                
        mutex_lock(&dev->struct_mutex);

        /* GEM does all our handle to object mapping */
        obj = drm_gem_object_lookup(dev, file, handle);
        if (obj == NULL) {
                ret = -ENOENT;
                goto unlock;
        }
        /* What validation is needed here ? */
        
        /* Make it mmapable */
        if (!obj->map_list.map) {
                ret = psb_gem_create_mmap_offset(obj);
                if (ret)
                        goto out;
        }
        /* GEM should really work out the hash offsets for us */
        *offset = (u64)obj->map_list.hash.key << PAGE_SHIFT;
out:
        drm_gem_object_unreference(obj);
unlock:
        mutex_unlock(&dev->struct_mutex);
        return ret;
}

/**
 *      psb_gem_create          -       create a mappable object
 *      @file: the DRM file of the client
 *      @dev: our device
 *      @size: the size requested
 *      @handlep: returned handle (opaque number)
 *
 *      Create a GEM object, fill in the boilerplate and attach a handle to
 *      it so that userspace can speak about it. This does the core work
 *      for the various methods that do/will create GEM objects for things
 */
static int psb_gem_create(struct drm_file *file,
        struct drm_device *dev, uint64_t size, uint32_t *handlep)
{
        struct gtt_range *r;
        int ret;
        u32 handle;

        size = roundup(size, PAGE_SIZE);

        /* Allocate our object - for now a direct gtt range which is not 
           stolen memory backed */
        r = psb_gtt_alloc_range(dev, size, "gem", 0);
        if (r == NULL)
                return -ENOSPC;
        /* Initialize the extra goodies GEM needs to do all the hard work */
        if (drm_gem_object_init(dev, &r->gem, size) != 0) {
                psb_gtt_free_range(dev, r);
                /* GEM doesn't give an error code and we don't have an
                   EGEMSUCKS so make something up for now - FIXME */
                return -ENOMEM;
        }
        /* Give the object a handle so we can carry it more easily */
        ret = drm_gem_handle_create(file, &r->gem, &handle);
        if (ret) {
                drm_gem_object_release(&r->gem);
                psb_gtt_free_range(dev, r);
                return ret;
        }
        /* We have the initial and handle reference but need only one now */
        drm_gem_object_unreference(&r->gem);
        *handlep = handle;
        return 0;
}

/**
 *      psb_gem_dumb_create     -       create a dumb buffer
 *      @drm_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 psb_gem_dumb_create(struct drm_file *file, struct drm_device *dev,
                        struct drm_mode_create_dumb *args)
{
        args->pitch = ALIGN(args->width * ((args->bpp + 7) / 8), 64);
        args->size = args->pitch * args->height;
        return psb_gem_create(file, dev, args->size, &args->handle);
}

/**
 *      psb_gem_dumb_destroy    -       destroy a dumb buffer
 *      @file: client file
 *      @dev: our DRM device
 *      @handle: the object handle
 *
 *      Destroy a handle that was created via psb_gem_dumb_create, at least
 *      we hope it was created that way. i915 seems to assume the caller
 *      does the checking but that might be worth review ! FIXME
 */
int psb_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);
}

/**
 *      psb_gem_fault           -       pagefault handler for GEM objects
 *      @vma: the VMA of the GEM object
 *      @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.
 *
 *      This code eventually needs to handle faulting objects in and out
 *      of the GART and repacking it when we run out of space. We can put
 *      that off for now and for our simple uses
 *
 *      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.
 *
 *      To avoid aliasing and cache funnies we want to map the object
 *      through the GART. For the moment this is slightly hackish. It would
 *      be nicer if GEM provided mmap opened/closed hooks for us giving
 *      the object so that we could track things nicely. That needs changes
 *      to the core GEM code so must be tackled post staging
 *
 *      FIXME
 */
int psb_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
        struct drm_gem_object *obj;
        struct gtt_range *r;
        int ret;
        unsigned long pfn;
        pgoff_t page_offset;
        struct drm_device *dev;

        obj = vma->vm_private_data;     /* GEM object */
        dev = obj->dev;

        r = container_of(obj, struct gtt_range, gem);   /* Get the gtt range */

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

        /* For now the mmap pins the object and it stays pinned. As things
           stand that will do us no harm */
        if (r->mmapping == 0) {
                ret = psb_gtt_pin(r);
                if (ret < 0) {
                        DRM_ERROR("gma500: pin failed: %d\n", ret);
                        goto fail;
                }
                r->mmapping = 1;
        }

        /* FIXME: Locking. We may also need to repack the GART sometimes */

        /* Page relative to the VMA start */
        page_offset = ((unsigned long) vmf->virtual_address - vma->vm_start)
                                >> PAGE_SHIFT;

        /* Bus address of the page is gart + object offset + page offset */
        /* Assumes gtt allocations are page aligned */
        pfn = (r->resource.start >> PAGE_SHIFT) + page_offset;

        pr_debug("Object GTT base at %p\n", (void *)(r->resource.start));
        pr_debug("Inserting %p pfn %lx, pa %lx\n", vmf->virtual_address,
                pfn, pfn << PAGE_SHIFT);

        ret = vm_insert_pfn(vma, (unsigned long)vmf->virtual_address, pfn);

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;
        }
}