/*
 * Copyright © 2008 Intel Corporation
 *
 * 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
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * 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 MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS 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:
 *    Eric Anholt <eric@anholt.net>
 *
 */

#include <linux/string.h>
#include <linux/bitops.h>
#include <drm/drmP.h>
#include <drm/i915_drm.h>
#include "i915_drv.h"

/** @file i915_gem_tiling.c
 *
 * Support for managing tiling state of buffer objects.
 *
 * The idea behind tiling is to increase cache hit rates by rearranging
 * pixel data so that a group of pixel accesses are in the same cacheline.
 * Performance improvement from doing this on the back/depth buffer are on
 * the order of 30%.
 *
 * Intel architectures make this somewhat more complicated, though, by
 * adjustments made to addressing of data when the memory is in interleaved
 * mode (matched pairs of DIMMS) to improve memory bandwidth.
 * For interleaved memory, the CPU sends every sequential 64 bytes
 * to an alternate memory channel so it can get the bandwidth from both.
 *
 * The GPU also rearranges its accesses for increased bandwidth to interleaved
 * memory, and it matches what the CPU does for non-tiled.  However, when tiled
 * it does it a little differently, since one walks addresses not just in the
 * X direction but also Y.  So, along with alternating channels when bit
 * 6 of the address flips, it also alternates when other bits flip --  Bits 9
 * (every 512 bytes, an X tile scanline) and 10 (every two X tile scanlines)
 * are common to both the 915 and 965-class hardware.
 *
 * The CPU also sometimes XORs in higher bits as well, to improve
 * bandwidth doing strided access like we do so frequently in graphics.  This
 * is called "Channel XOR Randomization" in the MCH documentation.  The result
 * is that the CPU is XORing in either bit 11 or bit 17 to bit 6 of its address
 * decode.
 *
 * All of this bit 6 XORing has an effect on our memory management,
 * as we need to make sure that the 3d driver can correctly address object
 * contents.
 *
 * If we don't have interleaved memory, all tiling is safe and no swizzling is
 * required.
 *
 * When bit 17 is XORed in, we simply refuse to tile at all.  Bit
 * 17 is not just a page offset, so as we page an objet out and back in,
 * individual pages in it will have different bit 17 addresses, resulting in
 * each 64 bytes being swapped with its neighbor!
 *
 * Otherwise, if interleaved, we have to tell the 3d driver what the address
 * swizzling it needs to do is, since it's writing with the CPU to the pages
 * (bit 6 and potentially bit 11 XORed in), and the GPU is reading from the
 * pages (bit 6, 9, and 10 XORed in), resulting in a cumulative bit swizzling
 * required by the CPU of XORing in bit 6, 9, 10, and potentially 11, in order
 * to match what the GPU expects.
 */

/**
 * Detects bit 6 swizzling of address lookup between IGD access and CPU
 * access through main memory.
 */
void
i915_gem_detect_bit_6_swizzle(struct drm_device *dev)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        uint32_t swizzle_x = I915_BIT_6_SWIZZLE_UNKNOWN;
        uint32_t swizzle_y = I915_BIT_6_SWIZZLE_UNKNOWN;

        if (IS_VALLEYVIEW(dev)) {
                swizzle_x = I915_BIT_6_SWIZZLE_NONE;
                swizzle_y = I915_BIT_6_SWIZZLE_NONE;
        } else if (INTEL_INFO(dev)->gen >= 6) {
                uint32_t dimm_c0, dimm_c1;
                dimm_c0 = I915_READ(MAD_DIMM_C0);
                dimm_c1 = I915_READ(MAD_DIMM_C1);
                dimm_c0 &= MAD_DIMM_A_SIZE_MASK | MAD_DIMM_B_SIZE_MASK;
                dimm_c1 &= MAD_DIMM_A_SIZE_MASK | MAD_DIMM_B_SIZE_MASK;
                /* Enable swizzling when the channels are populated with
                 * identically sized dimms. We don't need to check the 3rd
                 * channel because no cpu with gpu attached ships in that
                 * configuration. Also, swizzling only makes sense for 2
                 * channels anyway. */
                if (dimm_c0 == dimm_c1) {
                        swizzle_x = I915_BIT_6_SWIZZLE_9_10;
                        swizzle_y = I915_BIT_6_SWIZZLE_9;
                } else {
                        swizzle_x = I915_BIT_6_SWIZZLE_NONE;
                        swizzle_y = I915_BIT_6_SWIZZLE_NONE;
                }
        } else if (IS_GEN5(dev)) {
                /* On Ironlake whatever DRAM config, GPU always do
                 * same swizzling setup.
                 */
                swizzle_x = I915_BIT_6_SWIZZLE_9_10;
                swizzle_y = I915_BIT_6_SWIZZLE_9;
        } else if (IS_GEN2(dev)) {
                /* As far as we know, the 865 doesn't have these bit 6
                 * swizzling issues.
                 */
                swizzle_x = I915_BIT_6_SWIZZLE_NONE;
                swizzle_y = I915_BIT_6_SWIZZLE_NONE;
        } else if (IS_MOBILE(dev) || (IS_GEN3(dev) && !IS_G33(dev))) {
                uint32_t dcc;

                /* On 9xx chipsets, channel interleave by the CPU is
                 * determined by DCC.  For single-channel, neither the CPU
                 * nor the GPU do swizzling.  For dual channel interleaved,
                 * the GPU's interleave is bit 9 and 10 for X tiled, and bit
                 * 9 for Y tiled.  The CPU's interleave is independent, and
                 * can be based on either bit 11 (haven't seen this yet) or
                 * bit 17 (common).
                 */
                dcc = I915_READ(DCC);
                switch (dcc & DCC_ADDRESSING_MODE_MASK) {
                case DCC_ADDRESSING_MODE_SINGLE_CHANNEL:
                case DCC_ADDRESSING_MODE_DUAL_CHANNEL_ASYMMETRIC:
                        swizzle_x = I915_BIT_6_SWIZZLE_NONE;
                        swizzle_y = I915_BIT_6_SWIZZLE_NONE;
                        break;
                case DCC_ADDRESSING_MODE_DUAL_CHANNEL_INTERLEAVED:
                        if (dcc & DCC_CHANNEL_XOR_DISABLE) {
                                /* This is the base swizzling by the GPU for
                                 * tiled buffers.
                                 */
                                swizzle_x = I915_BIT_6_SWIZZLE_9_10;
                                swizzle_y = I915_BIT_6_SWIZZLE_9;
                        } else if ((dcc & DCC_CHANNEL_XOR_BIT_17) == 0) {
                                /* Bit 11 swizzling by the CPU in addition. */
                                swizzle_x = I915_BIT_6_SWIZZLE_9_10_11;
                                swizzle_y = I915_BIT_6_SWIZZLE_9_11;
                        } else {
                                /* Bit 17 swizzling by the CPU in addition. */
                                swizzle_x = I915_BIT_6_SWIZZLE_9_10_17;
                                swizzle_y = I915_BIT_6_SWIZZLE_9_17;
                        }
                        break;
                }
                if (dcc == 0xffffffff) {
                        DRM_ERROR("Couldn't read from MCHBAR.  "
                                  "Disabling tiling.\n");
                        swizzle_x = I915_BIT_6_SWIZZLE_UNKNOWN;
                        swizzle_y = I915_BIT_6_SWIZZLE_UNKNOWN;
                }
        } else {
                /* The 965, G33, and newer, have a very flexible memory
                 * configuration.  It will enable dual-channel mode
                 * (interleaving) on as much memory as it can, and the GPU
                 * will additionally sometimes enable different bit 6
                 * swizzling for tiled objects from the CPU.
                 *
                 * Here's what I found on the G965:
                 *    slot fill         memory size  swizzling
                 * 0A   0B   1A   1B    1-ch   2-ch
                 * 512  0    0    0     512    0     O
                 * 512  0    512  0     16     1008  X
                 * 512  0    0    512   16     1008  X
                 * 0    512  0    512   16     1008  X
                 * 1024 1024 1024 0     2048   1024  O
                 *
                 * We could probably detect this based on either the DRB
                 * matching, which was the case for the swizzling required in
                 * the table above, or from the 1-ch value being less than
                 * the minimum size of a rank.
                 */
                if (I915_READ16(C0DRB3) != I915_READ16(C1DRB3)) {
                        swizzle_x = I915_BIT_6_SWIZZLE_NONE;
                        swizzle_y = I915_BIT_6_SWIZZLE_NONE;
                } else {
                        swizzle_x = I915_BIT_6_SWIZZLE_9_10;
                        swizzle_y = I915_BIT_6_SWIZZLE_9;
                }
        }

        dev_priv->mm.bit_6_swizzle_x = swizzle_x;
        dev_priv->mm.bit_6_swizzle_y = swizzle_y;
}

/* Check pitch constriants for all chips & tiling formats */
static bool
i915_tiling_ok(struct drm_device *dev, int stride, int size, int tiling_mode)
{
        int tile_width;

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

        if (IS_GEN2(dev) ||
            (tiling_mode == I915_TILING_Y && HAS_128_BYTE_Y_TILING(dev)))
                tile_width = 128;
        else
                tile_width = 512;

        /* 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 (INTEL_INFO(dev)->gen >= 7) {
                if (stride / 128 > GEN7_FENCE_MAX_PITCH_VAL)
                        return false;
        } else if (INTEL_INFO(dev)->gen >= 4) {
                if (stride / 128 > I965_FENCE_MAX_PITCH_VAL)
                        return false;
        } else {
                if (stride > 8192)
                        return false;

                if (IS_GEN3(dev)) {
                        if (size > I830_FENCE_MAX_SIZE_VAL << 20)
                                return false;
                } else {
                        if (size > I830_FENCE_MAX_SIZE_VAL << 19)
                                return false;
                }
        }

        if (stride < tile_width)
                return false;

        /* 965+ just needs multiples of tile width */
        if (INTEL_INFO(dev)->gen >= 4) {
                if (stride & (tile_width - 1))
                        return false;
                return true;
        }

        /* Pre-965 needs power of two tile widths */
        if (stride & (stride - 1))
                return false;

        return true;
}

/* Is the current GTT allocation valid for the change in tiling? */
static bool
i915_gem_object_fence_ok(struct drm_i915_gem_object *obj, int tiling_mode)
{
        u32 size;

        if (tiling_mode == I915_TILING_NONE)
                return true;

        if (INTEL_INFO(obj->base.dev)->gen >= 4)
                return true;

        if (INTEL_INFO(obj->base.dev)->gen == 3) {
                if (i915_gem_obj_ggtt_offset(obj) & ~I915_FENCE_START_MASK)
                        return false;
        } else {
                if (i915_gem_obj_ggtt_offset(obj) & ~I830_FENCE_START_MASK)
                        return false;
        }

        size = i915_gem_get_gtt_size(obj->base.dev, obj->base.size, tiling_mode);
        if (i915_gem_obj_ggtt_size(obj) != size)
                return false;

        if (i915_gem_obj_ggtt_offset(obj) & (size - 1))
                return false;

        return true;
}

/**
 * Sets the tiling mode of an object, returning the required swizzling of
 * bit 6 of addresses in the object.
 */
int
i915_gem_set_tiling(struct drm_device *dev, void *data,
                   struct drm_file *file)
{
        struct drm_i915_gem_set_tiling *args = data;
        drm_i915_private_t *dev_priv = dev->dev_private;
        struct drm_i915_gem_object *obj;
        int ret = 0;

        obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->handle));
        if (&obj->base == NULL)
                return -ENOENT;

        if (!i915_tiling_ok(dev,
                            args->stride, obj->base.size, args->tiling_mode)) {
                drm_gem_object_unreference_unlocked(&obj->base);
                return -EINVAL;
        }

        if (obj->pin_count) {
                drm_gem_object_unreference_unlocked(&obj->base);
                return -EBUSY;
        }

        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 = dev_priv->mm.bit_6_swizzle_x;
                else
                        args->swizzle_mode = dev_priv->mm.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;
                }
        }

        mutex_lock(&dev->struct_mutex);
        if (args->tiling_mode != obj->tiling_mode ||
            args->stride != obj->stride) {
                /* 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.
                 */

                obj->map_and_fenceable =
                        !i915_gem_obj_ggtt_bound(obj) ||
                        (i915_gem_obj_ggtt_offset(obj) +
                         obj->base.size <= dev_priv->gtt.mappable_end &&
                         i915_gem_object_fence_ok(obj, args->tiling_mode));

                /* Rebind if we need a change of alignment */
                if (!obj->map_and_fenceable) {
                        u32 unfenced_align =
                                i915_gem_get_gtt_alignment(dev, obj->base.size,
                                                            args->tiling_mode,
                                                            false);
                        if (i915_gem_obj_ggtt_offset(obj) & (unfenced_align - 1))
                                ret = i915_gem_object_ggtt_unbind(obj);
                }

                if (ret == 0) {
                        obj->fence_dirty =
                                obj->fenced_gpu_access ||
                                obj->fence_reg != I915_FENCE_REG_NONE;

                        obj->tiling_mode = args->tiling_mode;
                        obj->stride = args->stride;

                        /* Force the fence to be reacquired for GTT access */
                        i915_gem_release_mmap(obj);
                }
        }
        /* we have to maintain this existing ABI... */
        args->stride = obj->stride;
        args->tiling_mode = obj->tiling_mode;

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

        drm_gem_object_unreference(&obj->base);
        mutex_unlock(&dev->struct_mutex);

        return ret;
}

/**
 * Returns the current tiling mode and required bit 6 swizzling for the object.
 */
int
i915_gem_get_tiling(struct drm_device *dev, void *data,
                   struct drm_file *file)
{
        struct drm_i915_gem_get_tiling *args = data;
        drm_i915_private_t *dev_priv = dev->dev_private;
        struct drm_i915_gem_object *obj;

        obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->handle));
        if (&obj->base == NULL)
                return -ENOENT;

        mutex_lock(&dev->struct_mutex);

        args->tiling_mode = obj->tiling_mode;
        switch (obj->tiling_mode) {
        case I915_TILING_X:
                args->swizzle_mode = dev_priv->mm.bit_6_swizzle_x;
                break;
        case I915_TILING_Y:
                args->swizzle_mode = dev_priv->mm.bit_6_swizzle_y;
                break;
        case I915_TILING_NONE:
                args->swizzle_mode = I915_BIT_6_SWIZZLE_NONE;
                break;
        default:
                DRM_ERROR("unknown tiling mode\n");
        }

        /* Hide bit 17 from the user -- see comment in i915_gem_set_tiling */
        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;

        drm_gem_object_unreference(&obj->base);
        mutex_unlock(&dev->struct_mutex);

        return 0;
}

/**
 * Swap every 64 bytes of this page around, to account for it having a new
 * bit 17 of its physical address and therefore being interpreted differently
 * by the GPU.
 */
static void
i915_gem_swizzle_page(struct page *page)
{
        char temp[64];
        char *vaddr;
        int i;

        vaddr = kmap(page);

        for (i = 0; i < PAGE_SIZE; i += 128) {
                memcpy(temp, &vaddr[i], 64);
                memcpy(&vaddr[i], &vaddr[i + 64], 64);
                memcpy(&vaddr[i + 64], temp, 64);
        }

        kunmap(page);
}

void
i915_gem_object_do_bit_17_swizzle(struct drm_i915_gem_object *obj)
{
        struct sg_page_iter sg_iter;
        int i;

        if (obj->bit_17 == NULL)
                return;

        i = 0;
        for_each_sg_page(obj->pages->sgl, &sg_iter, obj->pages->nents, 0) {
                struct page *page = sg_page_iter_page(&sg_iter);
                char new_bit_17 = page_to_phys(page) >> 17;
                if ((new_bit_17 & 0x1) !=
                    (test_bit(i, obj->bit_17) != 0)) {
                        i915_gem_swizzle_page(page);
                        set_page_dirty(page);
                }
                i++;
        }
}

void
i915_gem_object_save_bit_17_swizzle(struct drm_i915_gem_object *obj)
{
        struct sg_page_iter sg_iter;
        int page_count = obj->base.size >> PAGE_SHIFT;
        int i;

        if (obj->bit_17 == NULL) {
                obj->bit_17 = kmalloc(BITS_TO_LONGS(page_count) *
                                           sizeof(long), GFP_KERNEL);
                if (obj->bit_17 == NULL) {
                        DRM_ERROR("Failed to allocate memory for bit 17 "
                                  "record\n");
                        return;
                }
        }

        i = 0;
        for_each_sg_page(obj->pages->sgl, &sg_iter, obj->pages->nents, 0) {
                if (page_to_phys(sg_page_iter_page(&sg_iter)) & (1 << 17))
                        __set_bit(i, obj->bit_17);
                else
                        __clear_bit(i, obj->bit_17);
                i++;
        }
}