drm/i915: Extract i915_gem_fence.c

No code changes, just moving all the fence related code into a
separate file (and avoiding a bunch of forward declarations while at
it).

Acked-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>

drivers/gpu/drm/i915/Makefile

@@ -25,6 +25,7 @@ i915-y += i915_cmd_parser.o \
 	  i915_gem_dmabuf.o \
 	  i915_gem_evict.o \
 	  i915_gem_execbuffer.o \
+	  i915_gem_fence.o \
 	  i915_gem_gtt.o \
 	  i915_gem.o \
 	  i915_gem_render_state.o \

drivers/gpu/drm/i915/i915_drv.h

@@ -2868,11 +2868,6 @@ static inline bool i915_gem_request_completed(struct drm_i915_gem_request *req,
 
 int __must_check i915_gem_get_seqno(struct drm_device *dev, u32 *seqno);
 int __must_check i915_gem_set_seqno(struct drm_device *dev, u32 seqno);
-int __must_check i915_gem_object_get_fence(struct drm_i915_gem_object *obj);
-int __must_check i915_gem_object_put_fence(struct drm_i915_gem_object *obj);
-
-bool i915_gem_object_pin_fence(struct drm_i915_gem_object *obj);
-void i915_gem_object_unpin_fence(struct drm_i915_gem_object *obj);
 
 struct drm_i915_gem_request *
 i915_gem_find_active_request(struct intel_engine_cs *ring);
@@ -2970,8 +2965,6 @@ struct drm_gem_object *i915_gem_prime_import(struct drm_device *dev,
 struct dma_buf *i915_gem_prime_export(struct drm_device *dev,
 				struct drm_gem_object *gem_obj, int flags);
 
-void i915_gem_restore_fences(struct drm_device *dev);
-
 unsigned long
 i915_gem_obj_ggtt_offset_view(struct drm_i915_gem_object *o,
 			      const struct i915_ggtt_view *view);
@@ -3066,6 +3059,15 @@ i915_gem_object_ggtt_unpin(struct drm_i915_gem_object *obj)
 	i915_gem_object_ggtt_unpin_view(obj, &i915_ggtt_view_normal);
 }
 
+/* i915_gem_fence.c */
+int __must_check i915_gem_object_get_fence(struct drm_i915_gem_object *obj);
+int __must_check i915_gem_object_put_fence(struct drm_i915_gem_object *obj);
+
+bool i915_gem_object_pin_fence(struct drm_i915_gem_object *obj);
+void i915_gem_object_unpin_fence(struct drm_i915_gem_object *obj);
+
+void i915_gem_restore_fences(struct drm_device *dev);
+
 /* i915_gem_context.c */
 int __must_check i915_gem_context_init(struct drm_device *dev);
 void i915_gem_context_fini(struct drm_device *dev);

drivers/gpu/drm/i915/i915_gem.c

@@ -46,11 +46,6 @@ static void
 i915_gem_object_retire__write(struct drm_i915_gem_object *obj);
 static void
 i915_gem_object_retire__read(struct drm_i915_gem_object *obj, int ring);
-static void i915_gem_write_fence(struct drm_device *dev, int reg,
-				 struct drm_i915_gem_object *obj);
-static void i915_gem_object_update_fence(struct drm_i915_gem_object *obj,
-					 struct drm_i915_fence_reg *fence,
-					 bool enable);
 
 static bool cpu_cache_is_coherent(struct drm_device *dev,
 				  enum i915_cache_level level)
@@ -66,18 +61,6 @@ static bool cpu_write_needs_clflush(struct drm_i915_gem_object *obj)
 	return obj->pin_display;
 }
 
-static inline void i915_gem_object_fence_lost(struct drm_i915_gem_object *obj)
-{
-	if (obj->tiling_mode)
-		i915_gem_release_mmap(obj);
-
-	/* As we do not have an associated fence register, we will force
-	 * a tiling change if we ever need to acquire one.
-	 */
-	obj->fence_dirty = false;
-	obj->fence_reg = I915_FENCE_REG_NONE;
-}
-
 /* some bookkeeping */
 static void i915_gem_info_add_obj(struct drm_i915_private *dev_priv,
 				  size_t size)
@@ -2793,27 +2776,6 @@ static void i915_gem_reset_ring_cleanup(struct drm_i915_private *dev_priv,
 	}
 }
 
-void i915_gem_restore_fences(struct drm_device *dev)
-{
-	struct drm_i915_private *dev_priv = dev->dev_private;
-	int i;
-
-	for (i = 0; i < dev_priv->num_fence_regs; i++) {
-		struct drm_i915_fence_reg *reg = &dev_priv->fence_regs[i];
-
-		/*
-		 * Commit delayed tiling changes if we have an object still
-		 * attached to the fence, otherwise just clear the fence.
-		 */
-		if (reg->obj) {
-			i915_gem_object_update_fence(reg->obj, reg,
-						     reg->obj->tiling_mode);
-		} else {
-			i915_gem_write_fence(dev, i, NULL);
-		}
-	}
-}
-
 void i915_gem_reset(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
@@ -3340,343 +3302,6 @@ int i915_gpu_idle(struct drm_device *dev)
 	return 0;
 }
 
-static void i965_write_fence_reg(struct drm_device *dev, int reg,
-				 struct drm_i915_gem_object *obj)
-{
-	struct drm_i915_private *dev_priv = dev->dev_private;
-	int fence_reg;
-	int fence_pitch_shift;
-
-	if (INTEL_INFO(dev)->gen >= 6) {
-		fence_reg = FENCE_REG_SANDYBRIDGE_0;
-		fence_pitch_shift = SANDYBRIDGE_FENCE_PITCH_SHIFT;
-	} else {
-		fence_reg = FENCE_REG_965_0;
-		fence_pitch_shift = I965_FENCE_PITCH_SHIFT;
-	}
-
-	fence_reg += reg * 8;
-
-	/* To w/a incoherency with non-atomic 64-bit register updates,
-	 * we split the 64-bit update into two 32-bit writes. In order
-	 * for a partial fence not to be evaluated between writes, we
-	 * precede the update with write to turn off the fence register,
-	 * and only enable the fence as the last step.
-	 *
-	 * For extra levels of paranoia, we make sure each step lands
-	 * before applying the next step.
-	 */
-	I915_WRITE(fence_reg, 0);
-	POSTING_READ(fence_reg);
-
-	if (obj) {
-		u32 size = i915_gem_obj_ggtt_size(obj);
-		uint64_t val;
-
-		/* Adjust fence size to match tiled area */
-		if (obj->tiling_mode != I915_TILING_NONE) {
-			uint32_t row_size = obj->stride *
-				(obj->tiling_mode == I915_TILING_Y ? 32 : 8);
-			size = (size / row_size) * row_size;
-		}
-
-		val = (uint64_t)((i915_gem_obj_ggtt_offset(obj) + size - 4096) &
-				 0xfffff000) << 32;
-		val |= i915_gem_obj_ggtt_offset(obj) & 0xfffff000;
-		val |= (uint64_t)((obj->stride / 128) - 1) << fence_pitch_shift;
-		if (obj->tiling_mode == I915_TILING_Y)
-			val |= 1 << I965_FENCE_TILING_Y_SHIFT;
-		val |= I965_FENCE_REG_VALID;
-
-		I915_WRITE(fence_reg + 4, val >> 32);
-		POSTING_READ(fence_reg + 4);
-
-		I915_WRITE(fence_reg + 0, val);
-		POSTING_READ(fence_reg);
-	} else {
-		I915_WRITE(fence_reg + 4, 0);
-		POSTING_READ(fence_reg + 4);
-	}
-}
-
-static void i915_write_fence_reg(struct drm_device *dev, int reg,
-				 struct drm_i915_gem_object *obj)
-{
-	struct drm_i915_private *dev_priv = dev->dev_private;
-	u32 val;
-
-	if (obj) {
-		u32 size = i915_gem_obj_ggtt_size(obj);
-		int pitch_val;
-		int tile_width;
-
-		WARN((i915_gem_obj_ggtt_offset(obj) & ~I915_FENCE_START_MASK) ||
-		     (size & -size) != size ||
-		     (i915_gem_obj_ggtt_offset(obj) & (size - 1)),
-		     "object 0x%08lx [fenceable? %d] not 1M or pot-size (0x%08x) aligned\n",
-		     i915_gem_obj_ggtt_offset(obj), obj->map_and_fenceable, size);
-
-		if (obj->tiling_mode == I915_TILING_Y && HAS_128_BYTE_Y_TILING(dev))
-			tile_width = 128;
-		else
-			tile_width = 512;
-
-		/* Note: pitch better be a power of two tile widths */
-		pitch_val = obj->stride / tile_width;
-		pitch_val = ffs(pitch_val) - 1;
-
-		val = i915_gem_obj_ggtt_offset(obj);
-		if (obj->tiling_mode == I915_TILING_Y)
-			val |= 1 << I830_FENCE_TILING_Y_SHIFT;
-		val |= I915_FENCE_SIZE_BITS(size);
-		val |= pitch_val << I830_FENCE_PITCH_SHIFT;
-		val |= I830_FENCE_REG_VALID;
-	} else
-		val = 0;
-
-	if (reg < 8)
-		reg = FENCE_REG_830_0 + reg * 4;
-	else
-		reg = FENCE_REG_945_8 + (reg - 8) * 4;
-
-	I915_WRITE(reg, val);
-	POSTING_READ(reg);
-}
-
-static void i830_write_fence_reg(struct drm_device *dev, int reg,
-				struct drm_i915_gem_object *obj)
-{
-	struct drm_i915_private *dev_priv = dev->dev_private;
-	uint32_t val;
-
-	if (obj) {
-		u32 size = i915_gem_obj_ggtt_size(obj);
-		uint32_t pitch_val;
-
-		WARN((i915_gem_obj_ggtt_offset(obj) & ~I830_FENCE_START_MASK) ||
-		     (size & -size) != size ||
-		     (i915_gem_obj_ggtt_offset(obj) & (size - 1)),
-		     "object 0x%08lx not 512K or pot-size 0x%08x aligned\n",
-		     i915_gem_obj_ggtt_offset(obj), size);
-
-		pitch_val = obj->stride / 128;
-		pitch_val = ffs(pitch_val) - 1;
-
-		val = i915_gem_obj_ggtt_offset(obj);
-		if (obj->tiling_mode == I915_TILING_Y)
-			val |= 1 << I830_FENCE_TILING_Y_SHIFT;
-		val |= I830_FENCE_SIZE_BITS(size);
-		val |= pitch_val << I830_FENCE_PITCH_SHIFT;
-		val |= I830_FENCE_REG_VALID;
-	} else
-		val = 0;
-
-	I915_WRITE(FENCE_REG_830_0 + reg * 4, val);
-	POSTING_READ(FENCE_REG_830_0 + reg * 4);
-}
-
-inline static bool i915_gem_object_needs_mb(struct drm_i915_gem_object *obj)
-{
-	return obj && obj->base.read_domains & I915_GEM_DOMAIN_GTT;
-}
-
-static void i915_gem_write_fence(struct drm_device *dev, int reg,
-				 struct drm_i915_gem_object *obj)
-{
-	struct drm_i915_private *dev_priv = dev->dev_private;
-
-	/* Ensure that all CPU reads are completed before installing a fence
-	 * and all writes before removing the fence.
-	 */
-	if (i915_gem_object_needs_mb(dev_priv->fence_regs[reg].obj))
-		mb();
-
-	WARN(obj && (!obj->stride || !obj->tiling_mode),
-	     "bogus fence setup with stride: 0x%x, tiling mode: %i\n",
-	     obj->stride, obj->tiling_mode);
-
-	if (IS_GEN2(dev))
-		i830_write_fence_reg(dev, reg, obj);
-	else if (IS_GEN3(dev))
-		i915_write_fence_reg(dev, reg, obj);
-	else if (INTEL_INFO(dev)->gen >= 4)
-		i965_write_fence_reg(dev, reg, obj);
-
-	/* And similarly be paranoid that no direct access to this region
-	 * is reordered to before the fence is installed.
-	 */
-	if (i915_gem_object_needs_mb(obj))
-		mb();
-}
-
-static inline int fence_number(struct drm_i915_private *dev_priv,
-			       struct drm_i915_fence_reg *fence)
-{
-	return fence - dev_priv->fence_regs;
-}
-
-static void i915_gem_object_update_fence(struct drm_i915_gem_object *obj,
-					 struct drm_i915_fence_reg *fence,
-					 bool enable)
-{
-	struct drm_i915_private *dev_priv = obj->base.dev->dev_private;
-	int reg = fence_number(dev_priv, fence);
-
-	i915_gem_write_fence(obj->base.dev, reg, enable ? obj : NULL);
-
-	if (enable) {
-		obj->fence_reg = reg;
-		fence->obj = obj;
-		list_move_tail(&fence->lru_list, &dev_priv->mm.fence_list);
-	} else {
-		obj->fence_reg = I915_FENCE_REG_NONE;
-		fence->obj = NULL;
-		list_del_init(&fence->lru_list);
-	}
-	obj->fence_dirty = false;
-}
-
-static int
-i915_gem_object_wait_fence(struct drm_i915_gem_object *obj)
-{
-	if (obj->last_fenced_req) {
-		int ret = i915_wait_request(obj->last_fenced_req);
-		if (ret)
-			return ret;
-
-		i915_gem_request_assign(&obj->last_fenced_req, NULL);
-	}
-
-	return 0;
-}
-
-int
-i915_gem_object_put_fence(struct drm_i915_gem_object *obj)
-{
-	struct drm_i915_private *dev_priv = obj->base.dev->dev_private;
-	struct drm_i915_fence_reg *fence;
-	int ret;
-
-	ret = i915_gem_object_wait_fence(obj);
-	if (ret)
-		return ret;
-
-	if (obj->fence_reg == I915_FENCE_REG_NONE)
-		return 0;
-
-	fence = &dev_priv->fence_regs[obj->fence_reg];
-
-	if (WARN_ON(fence->pin_count))
-		return -EBUSY;
-
-	i915_gem_object_fence_lost(obj);
-	i915_gem_object_update_fence(obj, fence, false);
-
-	return 0;
-}
-
-static struct drm_i915_fence_reg *
-i915_find_fence_reg(struct drm_device *dev)
-{
-	struct drm_i915_private *dev_priv = dev->dev_private;
-	struct drm_i915_fence_reg *reg, *avail;
-	int i;
-
-	/* First try to find a free reg */
-	avail = NULL;
-	for (i = dev_priv->fence_reg_start; i < dev_priv->num_fence_regs; i++) {
-		reg = &dev_priv->fence_regs[i];
-		if (!reg->obj)
-			return reg;
-
-		if (!reg->pin_count)
-			avail = reg;
-	}
-
-	if (avail == NULL)
-		goto deadlock;
-
-	/* None available, try to steal one or wait for a user to finish */
-	list_for_each_entry(reg, &dev_priv->mm.fence_list, lru_list) {
-		if (reg->pin_count)
-			continue;
-
-		return reg;
-	}
-
-deadlock:
-	/* Wait for completion of pending flips which consume fences */
-	if (intel_has_pending_fb_unpin(dev))
-		return ERR_PTR(-EAGAIN);
-
-	return ERR_PTR(-EDEADLK);
-}
-
-/**
- * i915_gem_object_get_fence - set up fencing for an object
- * @obj: object to map through a fence reg
- *
- * When mapping objects through the GTT, userspace wants to be able to write
- * to them without having to worry about swizzling if the object is tiled.
- * This function walks the fence regs looking for a free one for @obj,
- * stealing one if it can't find any.
- *
- * It then sets up the reg based on the object's properties: address, pitch
- * and tiling format.
- *
- * For an untiled surface, this removes any existing fence.
- */
-int
-i915_gem_object_get_fence(struct drm_i915_gem_object *obj)
-{
-	struct drm_device *dev = obj->base.dev;
-	struct drm_i915_private *dev_priv = dev->dev_private;
-	bool enable = obj->tiling_mode != I915_TILING_NONE;
-	struct drm_i915_fence_reg *reg;
-	int ret;
-
-	/* Have we updated the tiling parameters upon the object and so
-	 * will need to serialise the write to the associated fence register?
-	 */
-	if (obj->fence_dirty) {
-		ret = i915_gem_object_wait_fence(obj);
-		if (ret)
-			return ret;
-	}
-
-	/* Just update our place in the LRU if our fence is getting reused. */
-	if (obj->fence_reg != I915_FENCE_REG_NONE) {
-		reg = &dev_priv->fence_regs[obj->fence_reg];
-		if (!obj->fence_dirty) {
-			list_move_tail(&reg->lru_list,
-				       &dev_priv->mm.fence_list);
-			return 0;
-		}
-	} else if (enable) {
-		if (WARN_ON(!obj->map_and_fenceable))
-			return -EINVAL;
-
-		reg = i915_find_fence_reg(dev);
-		if (IS_ERR(reg))
-			return PTR_ERR(reg);
-
-		if (reg->obj) {
-			struct drm_i915_gem_object *old = reg->obj;
-
-			ret = i915_gem_object_wait_fence(old);
-			if (ret)
-				return ret;
-
-			i915_gem_object_fence_lost(old);
-		}
-	} else
-		return 0;
-
-	i915_gem_object_update_fence(obj, reg, enable);
-
-	return 0;
-}
-
 static bool i915_gem_valid_gtt_space(struct i915_vma *vma,
 				     unsigned long cache_level)
 {
@@ -4476,32 +4101,6 @@ i915_gem_object_ggtt_unpin_view(struct drm_i915_gem_object *obj,
 	--vma->pin_count;
 }
 
-bool
-i915_gem_object_pin_fence(struct drm_i915_gem_object *obj)
-{
-	if (obj->fence_reg != I915_FENCE_REG_NONE) {
-		struct drm_i915_private *dev_priv = obj->base.dev->dev_private;
-		struct i915_vma *ggtt_vma = i915_gem_obj_to_ggtt(obj);
-
-		WARN_ON(!ggtt_vma ||
-			dev_priv->fence_regs[obj->fence_reg].pin_count >
-			ggtt_vma->pin_count);
-		dev_priv->fence_regs[obj->fence_reg].pin_count++;
-		return true;
-	} else
-		return false;
-}
-
-void
-i915_gem_object_unpin_fence(struct drm_i915_gem_object *obj)
-{
-	if (obj->fence_reg != I915_FENCE_REG_NONE) {
-		struct drm_i915_private *dev_priv = obj->base.dev->dev_private;
-		WARN_ON(dev_priv->fence_regs[obj->fence_reg].pin_count <= 0);
-		dev_priv->fence_regs[obj->fence_reg].pin_count--;
-	}
-}
-
 int
 i915_gem_busy_ioctl(struct drm_device *dev, void *data,
 		    struct drm_file *file)

drivers/gpu/drm/i915/i915_gem_fence.c

@@ -0,0 +1,422 @@
+/*
+ * Copyright © 2008-2015 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.
+ */
+
+#include <drm/drmP.h>
+#include <drm/i915_drm.h>
+#include "i915_drv.h"
+
+static void i965_write_fence_reg(struct drm_device *dev, int reg,
+				 struct drm_i915_gem_object *obj)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	int fence_reg;
+	int fence_pitch_shift;
+
+	if (INTEL_INFO(dev)->gen >= 6) {
+		fence_reg = FENCE_REG_SANDYBRIDGE_0;
+		fence_pitch_shift = SANDYBRIDGE_FENCE_PITCH_SHIFT;
+	} else {
+		fence_reg = FENCE_REG_965_0;
+		fence_pitch_shift = I965_FENCE_PITCH_SHIFT;
+	}
+
+	fence_reg += reg * 8;
+
+	/* To w/a incoherency with non-atomic 64-bit register updates,
+	 * we split the 64-bit update into two 32-bit writes. In order
+	 * for a partial fence not to be evaluated between writes, we
+	 * precede the update with write to turn off the fence register,
+	 * and only enable the fence as the last step.
+	 *
+	 * For extra levels of paranoia, we make sure each step lands
+	 * before applying the next step.
+	 */
+	I915_WRITE(fence_reg, 0);
+	POSTING_READ(fence_reg);
+
+	if (obj) {
+		u32 size = i915_gem_obj_ggtt_size(obj);
+		uint64_t val;
+
+		/* Adjust fence size to match tiled area */
+		if (obj->tiling_mode != I915_TILING_NONE) {
+			uint32_t row_size = obj->stride *
+				(obj->tiling_mode == I915_TILING_Y ? 32 : 8);
+			size = (size / row_size) * row_size;
+		}
+
+		val = (uint64_t)((i915_gem_obj_ggtt_offset(obj) + size - 4096) &
+				 0xfffff000) << 32;
+		val |= i915_gem_obj_ggtt_offset(obj) & 0xfffff000;
+		val |= (uint64_t)((obj->stride / 128) - 1) << fence_pitch_shift;
+		if (obj->tiling_mode == I915_TILING_Y)
+			val |= 1 << I965_FENCE_TILING_Y_SHIFT;
+		val |= I965_FENCE_REG_VALID;
+
+		I915_WRITE(fence_reg + 4, val >> 32);
+		POSTING_READ(fence_reg + 4);
+
+		I915_WRITE(fence_reg + 0, val);
+		POSTING_READ(fence_reg);
+	} else {
+		I915_WRITE(fence_reg + 4, 0);
+		POSTING_READ(fence_reg + 4);
+	}
+}
+
+static void i915_write_fence_reg(struct drm_device *dev, int reg,
+				 struct drm_i915_gem_object *obj)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	u32 val;
+
+	if (obj) {
+		u32 size = i915_gem_obj_ggtt_size(obj);
+		int pitch_val;
+		int tile_width;
+
+		WARN((i915_gem_obj_ggtt_offset(obj) & ~I915_FENCE_START_MASK) ||
+		     (size & -size) != size ||
+		     (i915_gem_obj_ggtt_offset(obj) & (size - 1)),
+		     "object 0x%08lx [fenceable? %d] not 1M or pot-size (0x%08x) aligned\n",
+		     i915_gem_obj_ggtt_offset(obj), obj->map_and_fenceable, size);
+
+		if (obj->tiling_mode == I915_TILING_Y && HAS_128_BYTE_Y_TILING(dev))
+			tile_width = 128;
+		else
+			tile_width = 512;
+
+		/* Note: pitch better be a power of two tile widths */
+		pitch_val = obj->stride / tile_width;
+		pitch_val = ffs(pitch_val) - 1;
+
+		val = i915_gem_obj_ggtt_offset(obj);
+		if (obj->tiling_mode == I915_TILING_Y)
+			val |= 1 << I830_FENCE_TILING_Y_SHIFT;
+		val |= I915_FENCE_SIZE_BITS(size);
+		val |= pitch_val << I830_FENCE_PITCH_SHIFT;
+		val |= I830_FENCE_REG_VALID;
+	} else
+		val = 0;
+
+	if (reg < 8)
+		reg = FENCE_REG_830_0 + reg * 4;
+	else
+		reg = FENCE_REG_945_8 + (reg - 8) * 4;
+
+	I915_WRITE(reg, val);
+	POSTING_READ(reg);
+}
+
+static void i830_write_fence_reg(struct drm_device *dev, int reg,
+				struct drm_i915_gem_object *obj)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	uint32_t val;
+
+	if (obj) {
+		u32 size = i915_gem_obj_ggtt_size(obj);
+		uint32_t pitch_val;
+
+		WARN((i915_gem_obj_ggtt_offset(obj) & ~I830_FENCE_START_MASK) ||
+		     (size & -size) != size ||
+		     (i915_gem_obj_ggtt_offset(obj) & (size - 1)),
+		     "object 0x%08lx not 512K or pot-size 0x%08x aligned\n",
+		     i915_gem_obj_ggtt_offset(obj), size);
+
+		pitch_val = obj->stride / 128;
+		pitch_val = ffs(pitch_val) - 1;
+
+		val = i915_gem_obj_ggtt_offset(obj);
+		if (obj->tiling_mode == I915_TILING_Y)
+			val |= 1 << I830_FENCE_TILING_Y_SHIFT;
+		val |= I830_FENCE_SIZE_BITS(size);
+		val |= pitch_val << I830_FENCE_PITCH_SHIFT;
+		val |= I830_FENCE_REG_VALID;
+	} else
+		val = 0;
+
+	I915_WRITE(FENCE_REG_830_0 + reg * 4, val);
+	POSTING_READ(FENCE_REG_830_0 + reg * 4);
+}
+
+inline static bool i915_gem_object_needs_mb(struct drm_i915_gem_object *obj)
+{
+	return obj && obj->base.read_domains & I915_GEM_DOMAIN_GTT;
+}
+
+static void i915_gem_write_fence(struct drm_device *dev, int reg,
+				 struct drm_i915_gem_object *obj)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+
+	/* Ensure that all CPU reads are completed before installing a fence
+	 * and all writes before removing the fence.
+	 */
+	if (i915_gem_object_needs_mb(dev_priv->fence_regs[reg].obj))
+		mb();
+
+	WARN(obj && (!obj->stride || !obj->tiling_mode),
+	     "bogus fence setup with stride: 0x%x, tiling mode: %i\n",
+	     obj->stride, obj->tiling_mode);
+
+	if (IS_GEN2(dev))
+		i830_write_fence_reg(dev, reg, obj);
+	else if (IS_GEN3(dev))
+		i915_write_fence_reg(dev, reg, obj);
+	else if (INTEL_INFO(dev)->gen >= 4)
+		i965_write_fence_reg(dev, reg, obj);
+
+	/* And similarly be paranoid that no direct access to this region
+	 * is reordered to before the fence is installed.
+	 */
+	if (i915_gem_object_needs_mb(obj))
+		mb();
+}
+
+static inline int fence_number(struct drm_i915_private *dev_priv,
+			       struct drm_i915_fence_reg *fence)
+{
+	return fence - dev_priv->fence_regs;
+}
+
+static void i915_gem_object_update_fence(struct drm_i915_gem_object *obj,
+					 struct drm_i915_fence_reg *fence,
+					 bool enable)
+{
+	struct drm_i915_private *dev_priv = obj->base.dev->dev_private;
+	int reg = fence_number(dev_priv, fence);
+
+	i915_gem_write_fence(obj->base.dev, reg, enable ? obj : NULL);
+
+	if (enable) {
+		obj->fence_reg = reg;
+		fence->obj = obj;
+		list_move_tail(&fence->lru_list, &dev_priv->mm.fence_list);
+	} else {
+		obj->fence_reg = I915_FENCE_REG_NONE;
+		fence->obj = NULL;
+		list_del_init(&fence->lru_list);
+	}
+	obj->fence_dirty = false;
+}
+
+static inline void i915_gem_object_fence_lost(struct drm_i915_gem_object *obj)
+{
+	if (obj->tiling_mode)
+		i915_gem_release_mmap(obj);
+
+	/* As we do not have an associated fence register, we will force
+	 * a tiling change if we ever need to acquire one.
+	 */
+	obj->fence_dirty = false;
+	obj->fence_reg = I915_FENCE_REG_NONE;
+}
+
+static int
+i915_gem_object_wait_fence(struct drm_i915_gem_object *obj)
+{
+	if (obj->last_fenced_req) {
+		int ret = i915_wait_request(obj->last_fenced_req);
+		if (ret)
+			return ret;
+
+		i915_gem_request_assign(&obj->last_fenced_req, NULL);
+	}
+
+	return 0;
+}
+
+int
+i915_gem_object_put_fence(struct drm_i915_gem_object *obj)
+{
+	struct drm_i915_private *dev_priv = obj->base.dev->dev_private;
+	struct drm_i915_fence_reg *fence;
+	int ret;
+
+	ret = i915_gem_object_wait_fence(obj);
+	if (ret)
+		return ret;
+
+	if (obj->fence_reg == I915_FENCE_REG_NONE)
+		return 0;
+
+	fence = &dev_priv->fence_regs[obj->fence_reg];
+
+	if (WARN_ON(fence->pin_count))
+		return -EBUSY;
+
+	i915_gem_object_fence_lost(obj);
+	i915_gem_object_update_fence(obj, fence, false);
+
+	return 0;
+}
+
+static struct drm_i915_fence_reg *
+i915_find_fence_reg(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct drm_i915_fence_reg *reg, *avail;
+	int i;
+
+	/* First try to find a free reg */
+	avail = NULL;
+	for (i = dev_priv->fence_reg_start; i < dev_priv->num_fence_regs; i++) {
+		reg = &dev_priv->fence_regs[i];
+		if (!reg->obj)
+			return reg;
+
+		if (!reg->pin_count)
+			avail = reg;
+	}
+
+	if (avail == NULL)
+		goto deadlock;
+
+	/* None available, try to steal one or wait for a user to finish */
+	list_for_each_entry(reg, &dev_priv->mm.fence_list, lru_list) {
+		if (reg->pin_count)
+			continue;
+
+		return reg;
+	}
+
+deadlock:
+	/* Wait for completion of pending flips which consume fences */
+	if (intel_has_pending_fb_unpin(dev))
+		return ERR_PTR(-EAGAIN);
+
+	return ERR_PTR(-EDEADLK);
+}
+
+/**
+ * i915_gem_object_get_fence - set up fencing for an object
+ * @obj: object to map through a fence reg
+ *
+ * When mapping objects through the GTT, userspace wants to be able to write
+ * to them without having to worry about swizzling if the object is tiled.
+ * This function walks the fence regs looking for a free one for @obj,
+ * stealing one if it can't find any.
+ *
+ * It then sets up the reg based on the object's properties: address, pitch
+ * and tiling format.
+ *
+ * For an untiled surface, this removes any existing fence.
+ */
+int
+i915_gem_object_get_fence(struct drm_i915_gem_object *obj)
+{
+	struct drm_device *dev = obj->base.dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	bool enable = obj->tiling_mode != I915_TILING_NONE;
+	struct drm_i915_fence_reg *reg;
+	int ret;
+
+	/* Have we updated the tiling parameters upon the object and so
+	 * will need to serialise the write to the associated fence register?
+	 */
+	if (obj->fence_dirty) {
+		ret = i915_gem_object_wait_fence(obj);
+		if (ret)
+			return ret;
+	}
+
+	/* Just update our place in the LRU if our fence is getting reused. */
+	if (obj->fence_reg != I915_FENCE_REG_NONE) {
+		reg = &dev_priv->fence_regs[obj->fence_reg];
+		if (!obj->fence_dirty) {
+			list_move_tail(&reg->lru_list,
+				       &dev_priv->mm.fence_list);
+			return 0;
+		}
+	} else if (enable) {
+		if (WARN_ON(!obj->map_and_fenceable))
+			return -EINVAL;
+
+		reg = i915_find_fence_reg(dev);
+		if (IS_ERR(reg))
+			return PTR_ERR(reg);
+
+		if (reg->obj) {
+			struct drm_i915_gem_object *old = reg->obj;
+
+			ret = i915_gem_object_wait_fence(old);
+			if (ret)
+				return ret;
+
+			i915_gem_object_fence_lost(old);
+		}
+	} else
+		return 0;
+
+	i915_gem_object_update_fence(obj, reg, enable);
+
+	return 0;
+}
+
+bool
+i915_gem_object_pin_fence(struct drm_i915_gem_object *obj)
+{
+	if (obj->fence_reg != I915_FENCE_REG_NONE) {
+		struct drm_i915_private *dev_priv = obj->base.dev->dev_private;
+		struct i915_vma *ggtt_vma = i915_gem_obj_to_ggtt(obj);
+
+		WARN_ON(!ggtt_vma ||
+			dev_priv->fence_regs[obj->fence_reg].pin_count >
+			ggtt_vma->pin_count);
+		dev_priv->fence_regs[obj->fence_reg].pin_count++;
+		return true;
+	} else
+		return false;
+}
+
+void
+i915_gem_object_unpin_fence(struct drm_i915_gem_object *obj)
+{
+	if (obj->fence_reg != I915_FENCE_REG_NONE) {
+		struct drm_i915_private *dev_priv = obj->base.dev->dev_private;
+		WARN_ON(dev_priv->fence_regs[obj->fence_reg].pin_count <= 0);
+		dev_priv->fence_regs[obj->fence_reg].pin_count--;
+	}
+}
+
+void i915_gem_restore_fences(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	int i;
+
+	for (i = 0; i < dev_priv->num_fence_regs; i++) {
+		struct drm_i915_fence_reg *reg = &dev_priv->fence_regs[i];
+
+		/*
+		 * Commit delayed tiling changes if we have an object still
+		 * attached to the fence, otherwise just clear the fence.
+		 */
+		if (reg->obj) {
+			i915_gem_object_update_fence(reg->obj, reg,
+						     reg->obj->tiling_mode);
+		} else {
+			i915_gem_write_fence(dev, i, NULL);
+		}
+	}
+}