/*
 * SPDX-License-Identifier: MIT
 *
 * Copyright © 2014-2016 Intel Corporation
 */

#include <linux/scatterlist.h>
#include <linux/slab.h>
#include <linux/swiotlb.h>

#include "i915_drv.h"
#include "i915_gem.h"
#include "i915_gem_object.h"
#include "i915_scatterlist.h"
#include "i915_utils.h"

#define QUIET (__GFP_NORETRY | __GFP_NOWARN)
#define MAYFAIL (__GFP_RETRY_MAYFAIL | __GFP_NOWARN)

static void internal_free_pages(struct sg_table *st)
{
        struct scatterlist *sg;

        for (sg = st->sgl; sg; sg = __sg_next(sg)) {
                if (sg_page(sg))
                        __free_pages(sg_page(sg), get_order(sg->length));
        }

        sg_free_table(st);
        kfree(st);
}

static int i915_gem_object_get_pages_internal(struct drm_i915_gem_object *obj)
{
        struct drm_i915_private *i915 = to_i915(obj->base.dev);
        struct sg_table *st;
        struct scatterlist *sg;
        unsigned int sg_page_sizes;
        unsigned int npages;
        int max_order;
        gfp_t gfp;

        max_order = MAX_ORDER;
#ifdef CONFIG_SWIOTLB
        if (is_swiotlb_active()) {
                unsigned int max_segment;

                max_segment = swiotlb_max_segment();
                if (max_segment) {
                        max_segment = max_t(unsigned int, max_segment,
                                            PAGE_SIZE) >> PAGE_SHIFT;
                        max_order = min(max_order, ilog2(max_segment));
                }
        }
#endif

        gfp = GFP_KERNEL | __GFP_HIGHMEM | __GFP_RECLAIMABLE;
        if (IS_I965GM(i915) || IS_I965G(i915)) {
                /* 965gm cannot relocate objects above 4GiB. */
                gfp &= ~__GFP_HIGHMEM;
                gfp |= __GFP_DMA32;
        }

create_st:
        st = kmalloc(sizeof(*st), GFP_KERNEL);
        if (!st)
                return -ENOMEM;

        npages = obj->base.size / PAGE_SIZE;
        if (sg_alloc_table(st, npages, GFP_KERNEL)) {
                kfree(st);
                return -ENOMEM;
        }

        sg = st->sgl;
        st->nents = 0;
        sg_page_sizes = 0;

        do {
                int order = min(fls(npages) - 1, max_order);
                struct page *page;

                do {
                        page = alloc_pages(gfp | (order ? QUIET : MAYFAIL),
                                           order);
                        if (page)
                                break;
                        if (!order--)
                                goto err;

                        /* Limit subsequent allocations as well */
                        max_order = order;
                } while (1);

                sg_set_page(sg, page, PAGE_SIZE << order, 0);
                sg_page_sizes |= PAGE_SIZE << order;
                st->nents++;

                npages -= 1 << order;
                if (!npages) {
                        sg_mark_end(sg);
                        break;
                }

                sg = __sg_next(sg);
        } while (1);

        if (i915_gem_gtt_prepare_pages(obj, st)) {
                /* Failed to dma-map try again with single page sg segments */
                if (get_order(st->sgl->length)) {
                        internal_free_pages(st);
                        max_order = 0;
                        goto create_st;
                }
                goto err;
        }

        __i915_gem_object_set_pages(obj, st, sg_page_sizes);

        return 0;

err:
        sg_set_page(sg, NULL, 0, 0);
        sg_mark_end(sg);
        internal_free_pages(st);

        return -ENOMEM;
}

static void i915_gem_object_put_pages_internal(struct drm_i915_gem_object *obj,
                                               struct sg_table *pages)
{
        i915_gem_gtt_finish_pages(obj, pages);
        internal_free_pages(pages);

        obj->mm.dirty = false;
}

static const struct drm_i915_gem_object_ops i915_gem_object_internal_ops = {
        .name = "i915_gem_object_internal",
        .flags = I915_GEM_OBJECT_IS_SHRINKABLE,
        .get_pages = i915_gem_object_get_pages_internal,
        .put_pages = i915_gem_object_put_pages_internal,
};

/**
 * i915_gem_object_create_internal: create an object with volatile pages
 * @i915: the i915 device
 * @size: the size in bytes of backing storage to allocate for the object
 *
 * Creates a new object that wraps some internal memory for private use.
 * This object is not backed by swappable storage, and as such its contents
 * are volatile and only valid whilst pinned. If the object is reaped by the
 * shrinker, its pages and data will be discarded. Equally, it is not a full
 * GEM object and so not valid for access from userspace. This makes it useful
 * for hardware interfaces like ringbuffers (which are pinned from the time
 * the request is written to the time the hardware stops accessing it), but
 * not for contexts (which need to be preserved when not active for later
 * reuse). Note that it is not cleared upon allocation.
 */
struct drm_i915_gem_object *
i915_gem_object_create_internal(struct drm_i915_private *i915,
                                phys_addr_t size)
{
        static struct lock_class_key lock_class;
        struct drm_i915_gem_object *obj;
        unsigned int cache_level;

        GEM_BUG_ON(!size);
        GEM_BUG_ON(!IS_ALIGNED(size, PAGE_SIZE));

        if (overflows_type(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, size);
        i915_gem_object_init(obj, &i915_gem_object_internal_ops, &lock_class,
                             I915_BO_ALLOC_STRUCT_PAGE);

        /*
         * Mark the object as volatile, such that the pages are marked as
         * dontneed whilst they are still pinned. As soon as they are unpinned
         * they are allowed to be reaped by the shrinker, and the caller is
         * expected to repopulate - the contents of this object are only valid
         * whilst active and pinned.
         */
        i915_gem_object_set_volatile(obj);

        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);

        return obj;
}