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/*

 * 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 

 *

 */

#include "linux/string.h"

#include "linux/bitops.h"

#include "drmP.h"

#include "drm.h"

#include "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.

 */

#define I915_TILING_NONE   0

#define I915_TILING_X       1

#define I915_TILING_Y       2

#define I915_BIT_6_SWIZZLE_NONE     0

#define I915_BIT_6_SWIZZLE_9        1

#define I915_BIT_6_SWIZZLE_9_10     2

#define I915_BIT_6_SWIZZLE_9_11     3

#define I915_BIT_6_SWIZZLE_9_10_11  4

/* Not seen by userland */

#define I915_BIT_6_SWIZZLE_UNKNOWN  5

/* Seen by userland. */

#define I915_BIT_6_SWIZZLE_9_17     6

#define I915_BIT_6_SWIZZLE_9_10_17  7

/**

 * 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 (INTEL_INFO(dev)->gen >= 5) {

		/* 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)) {

		uint32_t dcc;

		/* On mobile 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;

}

#if 0

/* 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 */

	if (INTEL_INFO(dev)->gen >= 4) {

		/* i965 stores the end address of the gtt mapping in the fence

		 * reg, so dont bother to check the size */

		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;

		}

	}

	/* 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 < tile_width)

		return false;

	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 (obj->gtt_offset & ~I915_FENCE_START_MASK)

			return false;

	} else {

		if (obj->gtt_offset & ~I830_FENCE_START_MASK)

			return false;

	}

	/*

	 * Previous chips need to be aligned to the size of the smallest

	 * fence register that can contain the object.

	 */

	if (INTEL_INFO(obj->base.dev)->gen == 3)

		size = 1024*1024;

	else

		size = 512*1024;

	while (size < obj->base.size)

		size <<= 1;

	if (obj->gtt_space->size != size)

		return false;

	if (obj->gtt_offset & (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 cleared.

		 */

		i915_gem_release_mmap(obj);

		obj->map_and_fenceable =

			obj->gtt_space == NULL ||

			(obj->gtt_offset + obj->base.size <= dev_priv->mm.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_alignment =

				i915_gem_get_unfenced_gtt_alignment(dev,

								    obj->base.size,

								    args->tiling_mode);

			if (obj->gtt_offset & (unfenced_alignment - 1))

				ret = i915_gem_object_unbind(obj);

		}

		if (ret == 0) {

			obj->tiling_changed = true;

			obj->tiling_mode = args->tiling_mode;

			obj->stride = args->stride;

		}

	}

	/* we have to maintain this existing ABI... */

	args->stride = obj->stride;

	args->tiling_mode = obj->tiling_mode;

	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 drm_device *dev = obj->base.dev;

	drm_i915_private_t *dev_priv = dev->dev_private;

	int page_count = obj->base.size >> PAGE_SHIFT;

	int i;

	if (dev_priv->mm.bit_6_swizzle_x != I915_BIT_6_SWIZZLE_9_10_17)

		return;

	if (obj->bit_17 == NULL)

		return;

	for (i = 0; i < page_count; i++) {

		char new_bit_17 = page_to_phys(obj->pages[i]) >> 17;

		if ((new_bit_17 & 0x1) !=

		    (test_bit(i, obj->bit_17) != 0)) {

			i915_gem_swizzle_page(obj->pages[i]);

			set_page_dirty(obj->pages[i]);

		}

	}

}

void

i915_gem_object_save_bit_17_swizzle(struct drm_i915_gem_object *obj)

{

	struct drm_device *dev = obj->base.dev;

	drm_i915_private_t *dev_priv = dev->dev_private;

	int page_count = obj->base.size >> PAGE_SHIFT;

	int i;

	if (dev_priv->mm.bit_6_swizzle_x != I915_BIT_6_SWIZZLE_9_10_17)

		return;

	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;

		}

	}

	for (i = 0; i < page_count; i++) {

		if (page_to_phys(obj->pages[i]) & (1 << 17))

			__set_bit(i, obj->bit_17);

		else

			__clear_bit(i, obj->bit_17);

	}

}

#endif