// SPDX-License-Identifier: MIT
/*
 * Copyright © 2008 Intel Corporation
 */

#include <linux/string.h>
#include <linux/bitops.h>

#include "i915_drv.h"
#include "i915_gem.h"
#include "i915_gem_ioctls.h"
#include "i915_gem_mman.h"
#include "i915_gem_object.h"
#include "i915_gem_tiling.h"
#include "i915_reg.h"

/**
 * DOC: buffer object tiling
 *
 * i915_gem_set_tiling_ioctl() and i915_gem_get_tiling_ioctl() is the userspace
 * interface to declare fence register requirements.
 *
 * In principle GEM doesn't care at all about the internal data layout of an
 * object, and hence it also doesn't care about tiling or swizzling. There's two
 * exceptions:
 *
 * - For X and Y tiling the hardware provides detilers for CPU access, so called
 *   fences. Since there's only a limited amount of them the kernel must manage
 *   these, and therefore userspace must tell the kernel the object tiling if it
 *   wants to use fences for detiling.
 * - On gen3 and gen4 platforms have a swizzling pattern for tiled objects which
 *   depends upon the physical page frame number. When swapping such objects the
 *   page frame number might change and the kernel must be able to fix this up
 *   and hence now the tiling. Note that on a subset of platforms with
 *   asymmetric memory channel population the swizzling pattern changes in an
 *   unknown way, and for those the kernel simply forbids swapping completely.
 *
 * Since neither of this applies for new tiling layouts on modern platforms like
 * W, Ys and Yf tiling GEM only allows object tiling to be set to X or Y tiled.
 * Anything else can be handled in userspace entirely without the kernel's
 * involvement.
 */

/**
 * i915_gem_fence_size - required global GTT size for a fence
 * @i915: i915 device
 * @size: object size
 * @tiling: tiling mode
 * @stride: tiling stride
 *
 * Return the required global GTT size for a fence (view of a tiled object),
 * taking into account potential fence register mapping.
 */
u32 i915_gem_fence_size(struct drm_i915_private *i915,
                        u32 size, unsigned int tiling, unsigned int stride)
{
        u32 ggtt_size;

        GEM_BUG_ON(!size);

        if (tiling == I915_TILING_NONE)
                return size;

        GEM_BUG_ON(!stride);

        if (GRAPHICS_VER(i915) >= 4) {
                stride *= i915_gem_tile_height(tiling);
                GEM_BUG_ON(!IS_ALIGNED(stride, I965_FENCE_PAGE));
                return roundup(size, stride);
        }

        /* Previous chips need a power-of-two fence region when tiling */
        if (GRAPHICS_VER(i915) == 3)
                ggtt_size = 1024*1024;
        else
                ggtt_size = 512*1024;

        while (ggtt_size < size)
                ggtt_size <<= 1;

        return ggtt_size;
}

/**
 * i915_gem_fence_alignment - required global GTT alignment for a fence
 * @i915: i915 device
 * @size: object size
 * @tiling: tiling mode
 * @stride: tiling stride
 *
 * Return the required global GTT alignment for a fence (a view of a tiled
 * object), taking into account potential fence register mapping.
 */
u32 i915_gem_fence_alignment(struct drm_i915_private *i915, u32 size,
                             unsigned int tiling, unsigned int stride)
{
        GEM_BUG_ON(!size);

        /*
         * Minimum alignment is 4k (GTT page size), but might be greater
         * if a fence register is needed for the object.
         */
        if (tiling == I915_TILING_NONE)
                return I915_GTT_MIN_ALIGNMENT;

        if (GRAPHICS_VER(i915) >= 4)
                return I965_FENCE_PAGE;

        /*
         * Previous chips need to be aligned to the size of the smallest
         * fence register that can contain the object.
         */
        return i915_gem_fence_size(i915, size, tiling, stride);
}

/* Check pitch constraints for all chips & tiling formats */
static bool
i915_tiling_ok(struct drm_i915_gem_object *obj,
               unsigned int tiling, unsigned int stride)
{
        struct drm_i915_private *i915 = to_i915(obj->base.dev);
        unsigned int tile_width;

        /* Linear is always fine */
        if (tiling == I915_TILING_NONE)
                return true;

        if (tiling > I915_TILING_LAST)
                return false;

        /* check maximum stride & object size */
        /* i965+ stores the end address of the gtt mapping in the fence
         * reg, so dont bother to check the size */
        if (GRAPHICS_VER(i915) >= 7) {
                if (stride / 128 > GEN7_FENCE_MAX_PITCH_VAL)
                        return false;
        } else if (GRAPHICS_VER(i915) >= 4) {
                if (stride / 128 > I965_FENCE_MAX_PITCH_VAL)
                        return false;
        } else {
                if (stride > 8192)
                        return false;

                if (!is_power_of_2(stride))
                        return false;
        }

        if (tiling == I915_TILING_Y && HAS_128_BYTE_Y_TILING(i915))
                tile_width = 128;
        else if (GRAPHICS_VER(i915) == 2)
                tile_width = 128;
        else
                tile_width = 512;

        if (!stride || !IS_ALIGNED(stride, tile_width))
                return false;

        return true;
}

static bool i915_vma_fence_prepare(struct i915_vma *vma,
                                   int tiling_mode, unsigned int stride)
{
        struct drm_i915_private *i915 = vma->vm->i915;
        u32 size, alignment;

        if (!i915_vma_is_map_and_fenceable(vma))
                return true;

        size = i915_gem_fence_size(i915, vma->size, tiling_mode, stride);
        if (i915_vma_size(vma) < size)
                return false;

        alignment = i915_gem_fence_alignment(i915, vma->size, tiling_mode, stride);
        if (!IS_ALIGNED(i915_ggtt_offset(vma), alignment))
                return false;

        return true;
}

/* Make the current GTT allocation valid for the change in tiling. */
static int
i915_gem_object_fence_prepare(struct drm_i915_gem_object *obj,
                              int tiling_mode, unsigned int stride)
{
        struct drm_i915_private *i915 = to_i915(obj->base.dev);
        struct i915_ggtt *ggtt = to_gt(i915)->ggtt;
        struct i915_vma *vma, *vn;
        LIST_HEAD(unbind);
        int ret = 0;

        if (tiling_mode == I915_TILING_NONE)
                return 0;

        mutex_lock(&ggtt->vm.mutex);

        spin_lock(&obj->vma.lock);
        for_each_ggtt_vma(vma, obj) {
                GEM_BUG_ON(vma->vm != &ggtt->vm);

                if (i915_vma_fence_prepare(vma, tiling_mode, stride))
                        continue;

                list_move(&vma->vm_link, &unbind);
        }
        spin_unlock(&obj->vma.lock);

        list_for_each_entry_safe(vma, vn, &unbind, vm_link) {
                ret = __i915_vma_unbind(vma);
                if (ret) {
                        /* Restore the remaining vma on an error */
                        list_splice(&unbind, &ggtt->vm.bound_list);
                        break;
                }
        }

        mutex_unlock(&ggtt->vm.mutex);

        return ret;
}

bool i915_gem_object_needs_bit17_swizzle(struct drm_i915_gem_object *obj)
{
        struct drm_i915_private *i915 = to_i915(obj->base.dev);

        return to_gt(i915)->ggtt->bit_6_swizzle_x == I915_BIT_6_SWIZZLE_9_10_17 &&
                i915_gem_object_is_tiled(obj);
}

int
i915_gem_object_set_tiling(struct drm_i915_gem_object *obj,
                           unsigned int tiling, unsigned int stride)
{
        struct drm_i915_private *i915 = to_i915(obj->base.dev);
        struct i915_vma *vma;
        int err;

        /* Make sure we don't cross-contaminate obj->tiling_and_stride */
        BUILD_BUG_ON(I915_TILING_LAST & STRIDE_MASK);

        GEM_BUG_ON(!i915_tiling_ok(obj, tiling, stride));
        GEM_BUG_ON(!stride ^ (tiling == I915_TILING_NONE));

        if ((tiling | stride) == obj->tiling_and_stride)
                return 0;

        if (i915_gem_object_is_framebuffer(obj))
                return -EBUSY;

        /* We need to rebind the object if its current allocation
         * no longer meets the alignment restrictions for its new
         * tiling mode. Otherwise we can just leave it alone, but
         * need to ensure that any fence register is updated before
         * the next fenced (either through the GTT or by the BLT unit
         * on older GPUs) access.
         *
         * After updating the tiling parameters, we then flag whether
         * we need to update an associated fence register. Note this
         * has to also include the unfenced register the GPU uses
         * whilst executing a fenced command for an untiled object.
         */

        i915_gem_object_lock(obj, NULL);
        if (i915_gem_object_is_framebuffer(obj)) {
                i915_gem_object_unlock(obj);
                return -EBUSY;
        }

        err = i915_gem_object_fence_prepare(obj, tiling, stride);
        if (err) {
                i915_gem_object_unlock(obj);
                return err;
        }

        /* If the memory has unknown (i.e. varying) swizzling, we pin the
         * pages to prevent them being swapped out and causing corruption
         * due to the change in swizzling.
         */
        if (i915_gem_object_has_pages(obj) &&
            obj->mm.madv == I915_MADV_WILLNEED &&
            i915->gem_quirks & GEM_QUIRK_PIN_SWIZZLED_PAGES) {
                if (tiling == I915_TILING_NONE) {
                        GEM_BUG_ON(!i915_gem_object_has_tiling_quirk(obj));
                        i915_gem_object_clear_tiling_quirk(obj);
                        i915_gem_object_make_shrinkable(obj);
                }
                if (!i915_gem_object_is_tiled(obj)) {
                        GEM_BUG_ON(i915_gem_object_has_tiling_quirk(obj));
                        i915_gem_object_make_unshrinkable(obj);
                        i915_gem_object_set_tiling_quirk(obj);
                }
        }

        spin_lock(&obj->vma.lock);
        for_each_ggtt_vma(vma, obj) {
                vma->fence_size =
                        i915_gem_fence_size(i915, vma->size, tiling, stride);
                vma->fence_alignment =
                        i915_gem_fence_alignment(i915,
                                                 vma->size, tiling, stride);

                if (vma->fence)
                        vma->fence->dirty = true;
        }
        spin_unlock(&obj->vma.lock);

        obj->tiling_and_stride = tiling | stride;

        /* Try to preallocate memory required to save swizzling on put-pages */
        if (i915_gem_object_needs_bit17_swizzle(obj)) {
                if (!obj->bit_17) {
                        obj->bit_17 = bitmap_zalloc(obj->base.size >> PAGE_SHIFT,
                                                    GFP_KERNEL);
                }
        } else {
                bitmap_free(obj->bit_17);
                obj->bit_17 = NULL;
        }

        i915_gem_object_unlock(obj);

        /* Force the fence to be reacquired for GTT access */
        i915_gem_object_release_mmap_gtt(obj);

        return 0;
}

/**
 * i915_gem_set_tiling_ioctl - IOCTL handler to set tiling mode
 * @dev: DRM device
 * @data: data pointer for the ioctl
 * @file: DRM file for the ioctl call
 *
 * Sets the tiling mode of an object, returning the required swizzling of
 * bit 6 of addresses in the object.
 *
 * Called by the user via ioctl.
 *
 * Returns:
 * Zero on success, negative errno on failure.
 */
int
i915_gem_set_tiling_ioctl(struct drm_device *dev, void *data,
                          struct drm_file *file)
{
        struct drm_i915_private *i915 = to_i915(dev);
        struct drm_i915_gem_set_tiling *args = data;
        struct drm_i915_gem_object *obj;
        int err;

        if (!to_gt(i915)->ggtt->num_fences)
                return -EOPNOTSUPP;

        obj = i915_gem_object_lookup(file, args->handle);
        if (!obj)
                return -ENOENT;

        /*
         * The tiling mode of proxy objects is handled by its generator, and
         * not allowed to be changed by userspace.
         */
        if (i915_gem_object_is_proxy(obj)) {
                err = -ENXIO;
                goto err;
        }

        if (!i915_tiling_ok(obj, args->tiling_mode, args->stride)) {
                err = -EINVAL;
                goto err;
        }

        if (args->tiling_mode == I915_TILING_NONE) {
                args->swizzle_mode = I915_BIT_6_SWIZZLE_NONE;
                args->stride = 0;
        } else {
                if (args->tiling_mode == I915_TILING_X)
                        args->swizzle_mode = to_gt(i915)->ggtt->bit_6_swizzle_x;
                else
                        args->swizzle_mode = to_gt(i915)->ggtt->bit_6_swizzle_y;

                /* Hide bit 17 swizzling from the user.  This prevents old Mesa
                 * from aborting the application on sw fallbacks to bit 17,
                 * and we use the pread/pwrite bit17 paths to swizzle for it.
                 * If there was a user that was relying on the swizzle
                 * information for drm_intel_bo_map()ed reads/writes this would
                 * break it, but we don't have any of those.
                 */
                if (args->swizzle_mode == I915_BIT_6_SWIZZLE_9_17)
                        args->swizzle_mode = I915_BIT_6_SWIZZLE_9;
                if (args->swizzle_mode == I915_BIT_6_SWIZZLE_9_10_17)
                        args->swizzle_mode = I915_BIT_6_SWIZZLE_9_10;

                /* If we can't handle the swizzling, make it untiled. */
                if (args->swizzle_mode == I915_BIT_6_SWIZZLE_UNKNOWN) {
                        args->tiling_mode = I915_TILING_NONE;
                        args->swizzle_mode = I915_BIT_6_SWIZZLE_NONE;
                        args->stride = 0;
                }
        }

        err = i915_gem_object_set_tiling(obj, args->tiling_mode, args->stride);

        /* We have to maintain this existing ABI... */
        args->stride = i915_gem_object_get_stride(obj);
        args->tiling_mode = i915_gem_object_get_tiling(obj);

err:
        i915_gem_object_put(obj);
        return err;
}

/**
 * i915_gem_get_tiling_ioctl - IOCTL handler to get tiling mode
 * @dev: DRM device
 * @data: data pointer for the ioctl
 * @file: DRM file for the ioctl call
 *
 * Returns the current tiling mode and required bit 6 swizzling for the object.
 *
 * Called by the user via ioctl.
 *
 * Returns:
 * Zero on success, negative errno on failure.
 */
int
i915_gem_get_tiling_ioctl(struct drm_device *dev, void *data,
                          struct drm_file *file)
{
        struct drm_i915_gem_get_tiling *args = data;
        struct drm_i915_private *i915 = to_i915(dev);
        struct drm_i915_gem_object *obj;
        int err = -ENOENT;

        if (!to_gt(i915)->ggtt->num_fences)
                return -EOPNOTSUPP;

        rcu_read_lock();
        obj = i915_gem_object_lookup_rcu(file, args->handle);
        if (obj) {
                args->tiling_mode =
                        READ_ONCE(obj->tiling_and_stride) & TILING_MASK;
                err = 0;
        }
        rcu_read_unlock();
        if (unlikely(err))
                return err;

        switch (args->tiling_mode) {
        case I915_TILING_X:
                args->swizzle_mode = to_gt(i915)->ggtt->bit_6_swizzle_x;
                break;
        case I915_TILING_Y:
                args->swizzle_mode = to_gt(i915)->ggtt->bit_6_swizzle_y;
                break;
        default:
        case I915_TILING_NONE:
                args->swizzle_mode = I915_BIT_6_SWIZZLE_NONE;
                break;
        }

        /* Hide bit 17 from the user -- see comment in i915_gem_set_tiling */
        if (i915->gem_quirks & GEM_QUIRK_PIN_SWIZZLED_PAGES)
                args->phys_swizzle_mode = I915_BIT_6_SWIZZLE_UNKNOWN;
        else
                args->phys_swizzle_mode = args->swizzle_mode;
        if (args->swizzle_mode == I915_BIT_6_SWIZZLE_9_17)
                args->swizzle_mode = I915_BIT_6_SWIZZLE_9;
        if (args->swizzle_mode == I915_BIT_6_SWIZZLE_9_10_17)
                args->swizzle_mode = I915_BIT_6_SWIZZLE_9_10;

        return 0;
}