/*
 * SPDX-License-Identifier: MIT
 *
 * Copyright © 2016 Intel Corporation
 */

#include "i915_scatterlist.h"

#include "huge_gem_object.h"

static void huge_free_pages(struct drm_i915_gem_object *obj,
                            struct sg_table *pages)
{
        unsigned long nreal = obj->scratch / PAGE_SIZE;
        struct sgt_iter sgt_iter;
        struct page *page;

        for_each_sgt_page(page, sgt_iter, pages) {
                __free_page(page);
                if (!--nreal)
                        break;
        }

        sg_free_table(pages);
        kfree(pages);
}

static int huge_get_pages(struct drm_i915_gem_object *obj)
{
#define GFP (GFP_KERNEL | __GFP_NOWARN | __GFP_RETRY_MAYFAIL)
        const unsigned long nreal = obj->scratch / PAGE_SIZE;
        unsigned int npages; /* restricted by sg_alloc_table */
        struct scatterlist *sg, *src, *end;
        struct sg_table *pages;
        unsigned long n;

        if (overflows_type(obj->base.size / PAGE_SIZE, npages))
                return -E2BIG;

        npages = obj->base.size / PAGE_SIZE;
        pages = kmalloc_obj(*pages, GFP);
        if (!pages)
                return -ENOMEM;

        if (sg_alloc_table(pages, npages, GFP)) {
                kfree(pages);
                return -ENOMEM;
        }

        sg = pages->sgl;
        for (n = 0; n < nreal; n++) {
                struct page *page;

                page = alloc_page(GFP | __GFP_HIGHMEM);
                if (!page) {
                        sg_mark_end(sg);
                        goto err;
                }

                sg_set_page(sg, page, PAGE_SIZE, 0);
                sg = __sg_next(sg);
        }
        if (nreal < npages) {
                for (end = sg, src = pages->sgl; sg; sg = __sg_next(sg)) {
                        sg_set_page(sg, sg_page(src), PAGE_SIZE, 0);
                        src = __sg_next(src);
                        if (src == end)
                                src = pages->sgl;
                }
        }

        if (i915_gem_gtt_prepare_pages(obj, pages))
                goto err;

        __i915_gem_object_set_pages(obj, pages);

        return 0;

err:
        huge_free_pages(obj, pages);
        return -ENOMEM;
#undef GFP
}

static void huge_put_pages(struct drm_i915_gem_object *obj,
                           struct sg_table *pages)
{
        i915_gem_gtt_finish_pages(obj, pages);
        huge_free_pages(obj, pages);

        obj->mm.dirty = false;
}

static const struct drm_i915_gem_object_ops huge_ops = {
        .name = "huge-gem",
        .get_pages = huge_get_pages,
        .put_pages = huge_put_pages,
};

struct drm_i915_gem_object *
huge_gem_object(struct drm_i915_private *i915,
                phys_addr_t phys_size,
                dma_addr_t dma_size)
{
        static struct lock_class_key lock_class;
        struct drm_i915_gem_object *obj;
        unsigned int cache_level;

        GEM_BUG_ON(!phys_size || phys_size > dma_size);
        GEM_BUG_ON(!IS_ALIGNED(phys_size, PAGE_SIZE));
        GEM_BUG_ON(!IS_ALIGNED(dma_size, I915_GTT_PAGE_SIZE));

        if (overflows_type(dma_size, obj->base.size))
                return ERR_PTR(-E2BIG);

        obj = i915_gem_object_alloc();
        if (!obj)
                return ERR_PTR(-ENOMEM);

        drm_gem_private_object_init(&i915->drm, &obj->base, dma_size);
        i915_gem_object_init(obj, &huge_ops, &lock_class, 0);
        obj->mem_flags |= I915_BO_FLAG_STRUCT_PAGE;

        obj->read_domains = I915_GEM_DOMAIN_CPU;
        obj->write_domain = I915_GEM_DOMAIN_CPU;
        cache_level = HAS_LLC(i915) ? I915_CACHE_LLC : I915_CACHE_NONE;
        i915_gem_object_set_cache_coherency(obj, cache_level);
        obj->scratch = phys_size;

        return obj;
}