intel_ringbuffer.c

/*
 * Copyright © 2008-2010 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>
 *    Zou Nan hai <nanhai.zou@intel.com>
 *    Xiang Hai hao<haihao.xiang@intel.com>
 *
 */

#include <linux/log2.h>
#include <drm/drmP.h>
#include "i915_drv.h"
#include <drm/i915_drm.h>
#include "i915_trace.h"
#include "intel_drv.h"

/* Rough estimate of the typical request size, performing a flush,
 * set-context and then emitting the batch.
 */
#define LEGACY_REQUEST_SIZE 200

int __intel_ring_space(int head, int tail, int size)
{
	int space = head - tail;
	if (space <= 0)
		space += size;
	return space - I915_RING_FREE_SPACE;
}

void intel_ring_update_space(struct intel_ringbuffer *ringbuf)
{
	if (ringbuf->last_retired_head != -1) {
		ringbuf->head = ringbuf->last_retired_head;
		ringbuf->last_retired_head = -1;
	}

	ringbuf->space = __intel_ring_space(ringbuf->head & HEAD_ADDR,
					    ringbuf->tail, ringbuf->size);
}

static void __intel_ring_advance(struct intel_engine_cs *engine)
{
	struct intel_ringbuffer *ringbuf = engine->buffer;
	ringbuf->tail &= ringbuf->size - 1;
	engine->write_tail(engine, ringbuf->tail);
}

static int
gen2_render_ring_flush(struct drm_i915_gem_request *req,
		       u32	invalidate_domains,
		       u32	flush_domains)
{
	struct intel_engine_cs *engine = req->engine;
	u32 cmd;
	int ret;

	cmd = MI_FLUSH;
	if (((invalidate_domains|flush_domains) & I915_GEM_DOMAIN_RENDER) == 0)
		cmd |= MI_NO_WRITE_FLUSH;

	if (invalidate_domains & I915_GEM_DOMAIN_SAMPLER)
		cmd |= MI_READ_FLUSH;

	ret = intel_ring_begin(req, 2);
	if (ret)
		return ret;

	intel_ring_emit(engine, cmd);
	intel_ring_emit(engine, MI_NOOP);
	intel_ring_advance(engine);

	return 0;
}

static int
gen4_render_ring_flush(struct drm_i915_gem_request *req,
		       u32	invalidate_domains,
		       u32	flush_domains)
{
	struct intel_engine_cs *engine = req->engine;
	u32 cmd;
	int ret;

	/*
	 * read/write caches:
	 *
	 * I915_GEM_DOMAIN_RENDER is always invalidated, but is
	 * only flushed if MI_NO_WRITE_FLUSH is unset.  On 965, it is
	 * also flushed at 2d versus 3d pipeline switches.
	 *
	 * read-only caches:
	 *
	 * I915_GEM_DOMAIN_SAMPLER is flushed on pre-965 if
	 * MI_READ_FLUSH is set, and is always flushed on 965.
	 *
	 * I915_GEM_DOMAIN_COMMAND may not exist?
	 *
	 * I915_GEM_DOMAIN_INSTRUCTION, which exists on 965, is
	 * invalidated when MI_EXE_FLUSH is set.
	 *
	 * I915_GEM_DOMAIN_VERTEX, which exists on 965, is
	 * invalidated with every MI_FLUSH.
	 *
	 * TLBs:
	 *
	 * On 965, TLBs associated with I915_GEM_DOMAIN_COMMAND
	 * and I915_GEM_DOMAIN_CPU in are invalidated at PTE write and
	 * I915_GEM_DOMAIN_RENDER and I915_GEM_DOMAIN_SAMPLER
	 * are flushed at any MI_FLUSH.
	 */

	cmd = MI_FLUSH | MI_NO_WRITE_FLUSH;
	if ((invalidate_domains|flush_domains) & I915_GEM_DOMAIN_RENDER)
		cmd &= ~MI_NO_WRITE_FLUSH;
	if (invalidate_domains & I915_GEM_DOMAIN_INSTRUCTION)
		cmd |= MI_EXE_FLUSH;

	if (invalidate_domains & I915_GEM_DOMAIN_COMMAND &&
	    (IS_G4X(req->i915) || IS_GEN5(req->i915)))
		cmd |= MI_INVALIDATE_ISP;

	ret = intel_ring_begin(req, 2);
	if (ret)
		return ret;

	intel_ring_emit(engine, cmd);
	intel_ring_emit(engine, MI_NOOP);
	intel_ring_advance(engine);

	return 0;
}

/**
 * Emits a PIPE_CONTROL with a non-zero post-sync operation, for
 * implementing two workarounds on gen6.  From section 1.4.7.1
 * "PIPE_CONTROL" of the Sandy Bridge PRM volume 2 part 1:
 *
 * [DevSNB-C+{W/A}] Before any depth stall flush (including those
 * produced by non-pipelined state commands), software needs to first
 * send a PIPE_CONTROL with no bits set except Post-Sync Operation !=
 * 0.
 *
 * [Dev-SNB{W/A}]: Before a PIPE_CONTROL with Write Cache Flush Enable
 * =1, a PIPE_CONTROL with any non-zero post-sync-op is required.
 *
 * And the workaround for these two requires this workaround first:
 *
 * [Dev-SNB{W/A}]: Pipe-control with CS-stall bit set must be sent
 * BEFORE the pipe-control with a post-sync op and no write-cache
 * flushes.
 *
 * And this last workaround is tricky because of the requirements on
 * that bit.  From section 1.4.7.2.3 "Stall" of the Sandy Bridge PRM
 * volume 2 part 1:
 *
 *     "1 of the following must also be set:
 *      - Render Target Cache Flush Enable ([12] of DW1)
 *      - Depth Cache Flush Enable ([0] of DW1)
 *      - Stall at Pixel Scoreboard ([1] of DW1)
 *      - Depth Stall ([13] of DW1)
 *      - Post-Sync Operation ([13] of DW1)
 *      - Notify Enable ([8] of DW1)"
 *
 * The cache flushes require the workaround flush that triggered this
 * one, so we can't use it.  Depth stall would trigger the same.
 * Post-sync nonzero is what triggered this second workaround, so we
 * can't use that one either.  Notify enable is IRQs, which aren't
 * really our business.  That leaves only stall at scoreboard.
 */
static int
intel_emit_post_sync_nonzero_flush(struct drm_i915_gem_request *req)
{
	struct intel_engine_cs *engine = req->engine;
	u32 scratch_addr = engine->scratch.gtt_offset + 2 * CACHELINE_BYTES;
	int ret;

	ret = intel_ring_begin(req, 6);
	if (ret)
		return ret;

	intel_ring_emit(engine, GFX_OP_PIPE_CONTROL(5));
	intel_ring_emit(engine, PIPE_CONTROL_CS_STALL |
			PIPE_CONTROL_STALL_AT_SCOREBOARD);
	intel_ring_emit(engine, scratch_addr | PIPE_CONTROL_GLOBAL_GTT); /* address */
	intel_ring_emit(engine, 0); /* low dword */
	intel_ring_emit(engine, 0); /* high dword */
	intel_ring_emit(engine, MI_NOOP);
	intel_ring_advance(engine);

	ret = intel_ring_begin(req, 6);
	if (ret)
		return ret;

	intel_ring_emit(engine, GFX_OP_PIPE_CONTROL(5));
	intel_ring_emit(engine, PIPE_CONTROL_QW_WRITE);
	intel_ring_emit(engine, scratch_addr | PIPE_CONTROL_GLOBAL_GTT); /* address */
	intel_ring_emit(engine, 0);
	intel_ring_emit(engine, 0);
	intel_ring_emit(engine, MI_NOOP);
	intel_ring_advance(engine);

	return 0;
}

static int
gen6_render_ring_flush(struct drm_i915_gem_request *req,
		       u32 invalidate_domains, u32 flush_domains)
{
	struct intel_engine_cs *engine = req->engine;
	u32 flags = 0;
	u32 scratch_addr = engine->scratch.gtt_offset + 2 * CACHELINE_BYTES;
	int ret;

	/* Force SNB workarounds for PIPE_CONTROL flushes */
	ret = intel_emit_post_sync_nonzero_flush(req);
	if (ret)
		return ret;

	/* Just flush everything.  Experiments have shown that reducing the
	 * number of bits based on the write domains has little performance
	 * impact.
	 */
	if (flush_domains) {
		flags |= PIPE_CONTROL_RENDER_TARGET_CACHE_FLUSH;
		flags |= PIPE_CONTROL_DEPTH_CACHE_FLUSH;
		/*
		 * Ensure that any following seqno writes only happen
		 * when the render cache is indeed flushed.
		 */
		flags |= PIPE_CONTROL_CS_STALL;
	}
	if (invalidate_domains) {
		flags |= PIPE_CONTROL_TLB_INVALIDATE;
		flags |= PIPE_CONTROL_INSTRUCTION_CACHE_INVALIDATE;
		flags |= PIPE_CONTROL_TEXTURE_CACHE_INVALIDATE;
		flags |= PIPE_CONTROL_VF_CACHE_INVALIDATE;
		flags |= PIPE_CONTROL_CONST_CACHE_INVALIDATE;
		flags |= PIPE_CONTROL_STATE_CACHE_INVALIDATE;
		/*
		 * TLB invalidate requires a post-sync write.
		 */
		flags |= PIPE_CONTROL_QW_WRITE | PIPE_CONTROL_CS_STALL;
	}

	ret = intel_ring_begin(req, 4);
	if (ret)
		return ret;

	intel_ring_emit(engine, GFX_OP_PIPE_CONTROL(4));
	intel_ring_emit(engine, flags);
	intel_ring_emit(engine, scratch_addr | PIPE_CONTROL_GLOBAL_GTT);
	intel_ring_emit(engine, 0);
	intel_ring_advance(engine);

	return 0;
}

static int
gen7_render_ring_cs_stall_wa(struct drm_i915_gem_request *req)
{
	struct intel_engine_cs *engine = req->engine;
	int ret;

	ret = intel_ring_begin(req, 4);
	if (ret)
		return ret;

	intel_ring_emit(engine, GFX_OP_PIPE_CONTROL(4));
	intel_ring_emit(engine, PIPE_CONTROL_CS_STALL |
			      PIPE_CONTROL_STALL_AT_SCOREBOARD);
	intel_ring_emit(engine, 0);
	intel_ring_emit(engine, 0);
	intel_ring_advance(engine);

	return 0;
}

static int
gen7_render_ring_flush(struct drm_i915_gem_request *req,
		       u32 invalidate_domains, u32 flush_domains)
{
	struct intel_engine_cs *engine = req->engine;
	u32 flags = 0;
	u32 scratch_addr = engine->scratch.gtt_offset + 2 * CACHELINE_BYTES;
	int ret;

	/*
	 * Ensure that any following seqno writes only happen when the render
	 * cache is indeed flushed.
	 *
	 * Workaround: 4th PIPE_CONTROL command (except the ones with only
	 * read-cache invalidate bits set) must have the CS_STALL bit set. We
	 * don't try to be clever and just set it unconditionally.
	 */
	flags |= PIPE_CONTROL_CS_STALL;

	/* Just flush everything.  Experiments have shown that reducing the
	 * number of bits based on the write domains has little performance
	 * impact.
	 */
	if (flush_domains) {
		flags |= PIPE_CONTROL_RENDER_TARGET_CACHE_FLUSH;
		flags |= PIPE_CONTROL_DEPTH_CACHE_FLUSH;
		flags |= PIPE_CONTROL_DC_FLUSH_ENABLE;
		flags |= PIPE_CONTROL_FLUSH_ENABLE;
	}
	if (invalidate_domains) {
		flags |= PIPE_CONTROL_TLB_INVALIDATE;
		flags |= PIPE_CONTROL_INSTRUCTION_CACHE_INVALIDATE;
		flags |= PIPE_CONTROL_TEXTURE_CACHE_INVALIDATE;
		flags |= PIPE_CONTROL_VF_CACHE_INVALIDATE;
		flags |= PIPE_CONTROL_CONST_CACHE_INVALIDATE;
		flags |= PIPE_CONTROL_STATE_CACHE_INVALIDATE;
		flags |= PIPE_CONTROL_MEDIA_STATE_CLEAR;
		/*
		 * TLB invalidate requires a post-sync write.
		 */
		flags |= PIPE_CONTROL_QW_WRITE;
		flags |= PIPE_CONTROL_GLOBAL_GTT_IVB;

		flags |= PIPE_CONTROL_STALL_AT_SCOREBOARD;

		/* Workaround: we must issue a pipe_control with CS-stall bit
		 * set before a pipe_control command that has the state cache
		 * invalidate bit set. */
		gen7_render_ring_cs_stall_wa(req);
	}

	ret = intel_ring_begin(req, 4);
	if (ret)
		return ret;

	intel_ring_emit(engine, GFX_OP_PIPE_CONTROL(4));
	intel_ring_emit(engine, flags);
	intel_ring_emit(engine, scratch_addr);
	intel_ring_emit(engine, 0);
	intel_ring_advance(engine);

	return 0;
}

static int
gen8_emit_pipe_control(struct drm_i915_gem_request *req,
		       u32 flags, u32 scratch_addr)
{
	struct intel_engine_cs *engine = req->engine;
	int ret;

	ret = intel_ring_begin(req, 6);
	if (ret)
		return ret;

	intel_ring_emit(engine, GFX_OP_PIPE_CONTROL(6));
	intel_ring_emit(engine, flags);
	intel_ring_emit(engine, scratch_addr);
	intel_ring_emit(engine, 0);
	intel_ring_emit(engine, 0);
	intel_ring_emit(engine, 0);
	intel_ring_advance(engine);

	return 0;
}

static int
gen8_render_ring_flush(struct drm_i915_gem_request *req,
		       u32 invalidate_domains, u32 flush_domains)
{
	u32 flags = 0;
	u32 scratch_addr = req->engine->scratch.gtt_offset + 2 * CACHELINE_BYTES;
	int ret;

	flags |= PIPE_CONTROL_CS_STALL;

	if (flush_domains) {
		flags |= PIPE_CONTROL_RENDER_TARGET_CACHE_FLUSH;
		flags |= PIPE_CONTROL_DEPTH_CACHE_FLUSH;
		flags |= PIPE_CONTROL_DC_FLUSH_ENABLE;
		flags |= PIPE_CONTROL_FLUSH_ENABLE;
	}
	if (invalidate_domains) {
		flags |= PIPE_CONTROL_TLB_INVALIDATE;
		flags |= PIPE_CONTROL_INSTRUCTION_CACHE_INVALIDATE;
		flags |= PIPE_CONTROL_TEXTURE_CACHE_INVALIDATE;
		flags |= PIPE_CONTROL_VF_CACHE_INVALIDATE;
		flags |= PIPE_CONTROL_CONST_CACHE_INVALIDATE;
		flags |= PIPE_CONTROL_STATE_CACHE_INVALIDATE;
		flags |= PIPE_CONTROL_QW_WRITE;
		flags |= PIPE_CONTROL_GLOBAL_GTT_IVB;

		/* WaCsStallBeforeStateCacheInvalidate:bdw,chv */
		ret = gen8_emit_pipe_control(req,
					     PIPE_CONTROL_CS_STALL |
					     PIPE_CONTROL_STALL_AT_SCOREBOARD,
					     0);
		if (ret)
			return ret;
	}

	return gen8_emit_pipe_control(req, flags, scratch_addr);
}

static void ring_write_tail(struct intel_engine_cs *engine,
			    u32 value)
{
	struct drm_i915_private *dev_priv = engine->i915;
	I915_WRITE_TAIL(engine, value);
}

u64 intel_ring_get_active_head(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;
	u64 acthd;

	if (INTEL_GEN(dev_priv) >= 8)
		acthd = I915_READ64_2x32(RING_ACTHD(engine->mmio_base),
					 RING_ACTHD_UDW(engine->mmio_base));
	else if (INTEL_GEN(dev_priv) >= 4)
		acthd = I915_READ(RING_ACTHD(engine->mmio_base));
	else
		acthd = I915_READ(ACTHD);

	return acthd;
}

static void ring_setup_phys_status_page(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;
	u32 addr;

	addr = dev_priv->status_page_dmah->busaddr;
	if (INTEL_GEN(dev_priv) >= 4)
		addr |= (dev_priv->status_page_dmah->busaddr >> 28) & 0xf0;
	I915_WRITE(HWS_PGA, addr);
}

static void intel_ring_setup_status_page(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;
	i915_reg_t mmio;

	/* The ring status page addresses are no longer next to the rest of
	 * the ring registers as of gen7.
	 */
	if (IS_GEN7(dev_priv)) {
		switch (engine->id) {
		case RCS:
			mmio = RENDER_HWS_PGA_GEN7;
			break;
		case BCS:
			mmio = BLT_HWS_PGA_GEN7;
			break;
		/*
		 * VCS2 actually doesn't exist on Gen7. Only shut up
		 * gcc switch check warning
		 */
		case VCS2:
		case VCS:
			mmio = BSD_HWS_PGA_GEN7;
			break;
		case VECS:
			mmio = VEBOX_HWS_PGA_GEN7;
			break;
		}
	} else if (IS_GEN6(dev_priv)) {
		mmio = RING_HWS_PGA_GEN6(engine->mmio_base);
	} else {
		/* XXX: gen8 returns to sanity */
		mmio = RING_HWS_PGA(engine->mmio_base);
	}

	I915_WRITE(mmio, (u32)engine->status_page.gfx_addr);
	POSTING_READ(mmio);

	/*
	 * Flush the TLB for this page
	 *
	 * FIXME: These two bits have disappeared on gen8, so a question
	 * arises: do we still need this and if so how should we go about
	 * invalidating the TLB?
	 */
	if (IS_GEN(dev_priv, 6, 7)) {
		i915_reg_t reg = RING_INSTPM(engine->mmio_base);

		/* ring should be idle before issuing a sync flush*/
		WARN_ON((I915_READ_MODE(engine) & MODE_IDLE) == 0);

		I915_WRITE(reg,
			   _MASKED_BIT_ENABLE(INSTPM_TLB_INVALIDATE |
					      INSTPM_SYNC_FLUSH));
		if (intel_wait_for_register(dev_priv,
					    reg, INSTPM_SYNC_FLUSH, 0,
					    1000))
			DRM_ERROR("%s: wait for SyncFlush to complete for TLB invalidation timed out\n",
				  engine->name);
	}
}

static bool stop_ring(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;

	if (!IS_GEN2(dev_priv)) {
		I915_WRITE_MODE(engine, _MASKED_BIT_ENABLE(STOP_RING));
		if (intel_wait_for_register(dev_priv,
					    RING_MI_MODE(engine->mmio_base),
					    MODE_IDLE,
					    MODE_IDLE,
					    1000)) {
			DRM_ERROR("%s : timed out trying to stop ring\n",
				  engine->name);
			/* Sometimes we observe that the idle flag is not
			 * set even though the ring is empty. So double
			 * check before giving up.
			 */
			if (I915_READ_HEAD(engine) != I915_READ_TAIL(engine))
				return false;
		}
	}

	I915_WRITE_CTL(engine, 0);
	I915_WRITE_HEAD(engine, 0);
	engine->write_tail(engine, 0);

	if (!IS_GEN2(dev_priv)) {
		(void)I915_READ_CTL(engine);
		I915_WRITE_MODE(engine, _MASKED_BIT_DISABLE(STOP_RING));
	}

	return (I915_READ_HEAD(engine) & HEAD_ADDR) == 0;
}

static int init_ring_common(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;
	struct intel_ringbuffer *ringbuf = engine->buffer;
	struct drm_i915_gem_object *obj = ringbuf->obj;
	int ret = 0;

	intel_uncore_forcewake_get(dev_priv, FORCEWAKE_ALL);

	if (!stop_ring(engine)) {
		/* G45 ring initialization often fails to reset head to zero */
		DRM_DEBUG_KMS("%s head not reset to zero "
			      "ctl %08x head %08x tail %08x start %08x\n",
			      engine->name,
			      I915_READ_CTL(engine),
			      I915_READ_HEAD(engine),
			      I915_READ_TAIL(engine),
			      I915_READ_START(engine));

		if (!stop_ring(engine)) {
			DRM_ERROR("failed to set %s head to zero "
				  "ctl %08x head %08x tail %08x start %08x\n",
				  engine->name,
				  I915_READ_CTL(engine),
				  I915_READ_HEAD(engine),
				  I915_READ_TAIL(engine),
				  I915_READ_START(engine));
			ret = -EIO;
			goto out;
		}
	}

	if (I915_NEED_GFX_HWS(dev_priv))
		intel_ring_setup_status_page(engine);
	else
		ring_setup_phys_status_page(engine);

	/* Enforce ordering by reading HEAD register back */
	I915_READ_HEAD(engine);

	/* Initialize the ring. This must happen _after_ we've cleared the ring
	 * registers with the above sequence (the readback of the HEAD registers
	 * also enforces ordering), otherwise the hw might lose the new ring
	 * register values. */
	I915_WRITE_START(engine, i915_gem_obj_ggtt_offset(obj));

	/* WaClearRingBufHeadRegAtInit:ctg,elk */
	if (I915_READ_HEAD(engine))
		DRM_DEBUG("%s initialization failed [head=%08x], fudging\n",
			  engine->name, I915_READ_HEAD(engine));
	I915_WRITE_HEAD(engine, 0);
	(void)I915_READ_HEAD(engine);

	I915_WRITE_CTL(engine,
			((ringbuf->size - PAGE_SIZE) & RING_NR_PAGES)
			| RING_VALID);

	/* If the head is still not zero, the ring is dead */
	if (wait_for((I915_READ_CTL(engine) & RING_VALID) != 0 &&
		     I915_READ_START(engine) == i915_gem_obj_ggtt_offset(obj) &&
		     (I915_READ_HEAD(engine) & HEAD_ADDR) == 0, 50)) {
		DRM_ERROR("%s initialization failed "
			  "ctl %08x (valid? %d) head %08x tail %08x start %08x [expected %08lx]\n",
			  engine->name,
			  I915_READ_CTL(engine),
			  I915_READ_CTL(engine) & RING_VALID,
			  I915_READ_HEAD(engine), I915_READ_TAIL(engine),
			  I915_READ_START(engine),
			  (unsigned long)i915_gem_obj_ggtt_offset(obj));
		ret = -EIO;
		goto out;
	}

	ringbuf->last_retired_head = -1;
	ringbuf->head = I915_READ_HEAD(engine);
	ringbuf->tail = I915_READ_TAIL(engine) & TAIL_ADDR;
	intel_ring_update_space(ringbuf);

	intel_engine_init_hangcheck(engine);

out:
	intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);

	return ret;
}

void intel_fini_pipe_control(struct intel_engine_cs *engine)
{
	if (engine->scratch.obj == NULL)
		return;

	i915_gem_object_ggtt_unpin(engine->scratch.obj);
	i915_gem_object_put(engine->scratch.obj);
	engine->scratch.obj = NULL;
}

int intel_init_pipe_control(struct intel_engine_cs *engine, int size)
{
	struct drm_i915_gem_object *obj;
	int ret;

	WARN_ON(engine->scratch.obj);

	obj = i915_gem_object_create_stolen(&engine->i915->drm, size);
	if (!obj)
		obj = i915_gem_object_create(&engine->i915->drm, size);
	if (IS_ERR(obj)) {
		DRM_ERROR("Failed to allocate scratch page\n");
		ret = PTR_ERR(obj);
		goto err;
	}

	ret = i915_gem_obj_ggtt_pin(obj, 4096, PIN_HIGH);
	if (ret)
		goto err_unref;

	engine->scratch.obj = obj;
	engine->scratch.gtt_offset = i915_gem_obj_ggtt_offset(obj);
	DRM_DEBUG_DRIVER("%s pipe control offset: 0x%08x\n",
			 engine->name, engine->scratch.gtt_offset);
	return 0;

err_unref:
	i915_gem_object_put(engine->scratch.obj);
err:
	return ret;
}

static int intel_ring_workarounds_emit(struct drm_i915_gem_request *req)
{
	struct intel_engine_cs *engine = req->engine;
	struct i915_workarounds *w = &req->i915->workarounds;
	int ret, i;

	if (w->count == 0)
		return 0;

	engine->gpu_caches_dirty = true;
	ret = intel_ring_flush_all_caches(req);
	if (ret)
		return ret;

	ret = intel_ring_begin(req, (w->count * 2 + 2));
	if (ret)
		return ret;

	intel_ring_emit(engine, MI_LOAD_REGISTER_IMM(w->count));
	for (i = 0; i < w->count; i++) {
		intel_ring_emit_reg(engine, w->reg[i].addr);
		intel_ring_emit(engine, w->reg[i].value);
	}
	intel_ring_emit(engine, MI_NOOP);

	intel_ring_advance(engine);

	engine->gpu_caches_dirty = true;
	ret = intel_ring_flush_all_caches(req);
	if (ret)
		return ret;

	DRM_DEBUG_DRIVER("Number of Workarounds emitted: %d\n", w->count);

	return 0;
}

static int intel_rcs_ctx_init(struct drm_i915_gem_request *req)
{
	int ret;

	ret = intel_ring_workarounds_emit(req);
	if (ret != 0)
		return ret;

	ret = i915_gem_render_state_init(req);
	if (ret)
		return ret;

	return 0;
}

static int wa_add(struct drm_i915_private *dev_priv,
		  i915_reg_t addr,
		  const u32 mask, const u32 val)
{
	const u32 idx = dev_priv->workarounds.count;

	if (WARN_ON(idx >= I915_MAX_WA_REGS))
		return -ENOSPC;

	dev_priv->workarounds.reg[idx].addr = addr;
	dev_priv->workarounds.reg[idx].value = val;
	dev_priv->workarounds.reg[idx].mask = mask;

	dev_priv->workarounds.count++;

	return 0;
}

#define WA_REG(addr, mask, val) do { \
		const int r = wa_add(dev_priv, (addr), (mask), (val)); \
		if (r) \
			return r; \
	} while (0)

#define WA_SET_BIT_MASKED(addr, mask) \
	WA_REG(addr, (mask), _MASKED_BIT_ENABLE(mask))

#define WA_CLR_BIT_MASKED(addr, mask) \
	WA_REG(addr, (mask), _MASKED_BIT_DISABLE(mask))

#define WA_SET_FIELD_MASKED(addr, mask, value) \
	WA_REG(addr, mask, _MASKED_FIELD(mask, value))

#define WA_SET_BIT(addr, mask) WA_REG(addr, mask, I915_READ(addr) | (mask))
#define WA_CLR_BIT(addr, mask) WA_REG(addr, mask, I915_READ(addr) & ~(mask))

#define WA_WRITE(addr, val) WA_REG(addr, 0xffffffff, val)

static int wa_ring_whitelist_reg(struct intel_engine_cs *engine,
				 i915_reg_t reg)
{
	struct drm_i915_private *dev_priv = engine->i915;
	struct i915_workarounds *wa = &dev_priv->workarounds;
	const uint32_t index = wa->hw_whitelist_count[engine->id];

	if (WARN_ON(index >= RING_MAX_NONPRIV_SLOTS))
		return -EINVAL;

	WA_WRITE(RING_FORCE_TO_NONPRIV(engine->mmio_base, index),
		 i915_mmio_reg_offset(reg));
	wa->hw_whitelist_count[engine->id]++;

	return 0;
}

static int gen8_init_workarounds(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;

	WA_SET_BIT_MASKED(INSTPM, INSTPM_FORCE_ORDERING);

	/* WaDisableAsyncFlipPerfMode:bdw,chv */
	WA_SET_BIT_MASKED(MI_MODE, ASYNC_FLIP_PERF_DISABLE);

	/* WaDisablePartialInstShootdown:bdw,chv */
	WA_SET_BIT_MASKED(GEN8_ROW_CHICKEN,
			  PARTIAL_INSTRUCTION_SHOOTDOWN_DISABLE);

	/* Use Force Non-Coherent whenever executing a 3D context. This is a
	 * workaround for for a possible hang in the unlikely event a TLB
	 * invalidation occurs during a PSD flush.
	 */
	/* WaForceEnableNonCoherent:bdw,chv */
	/* WaHdcDisableFetchWhenMasked:bdw,chv */
	WA_SET_BIT_MASKED(HDC_CHICKEN0,
			  HDC_DONOT_FETCH_MEM_WHEN_MASKED |
			  HDC_FORCE_NON_COHERENT);

	/* From the Haswell PRM, Command Reference: Registers, CACHE_MODE_0:
	 * "The Hierarchical Z RAW Stall Optimization allows non-overlapping
	 *  polygons in the same 8x4 pixel/sample area to be processed without
	 *  stalling waiting for the earlier ones to write to Hierarchical Z
	 *  buffer."
	 *
	 * This optimization is off by default for BDW and CHV; turn it on.
	 */
	WA_CLR_BIT_MASKED(CACHE_MODE_0_GEN7, HIZ_RAW_STALL_OPT_DISABLE);

	/* Wa4x4STCOptimizationDisable:bdw,chv */
	WA_SET_BIT_MASKED(CACHE_MODE_1, GEN8_4x4_STC_OPTIMIZATION_DISABLE);

	/*
	 * BSpec recommends 8x4 when MSAA is used,
	 * however in practice 16x4 seems fastest.
	 *
	 * Note that PS/WM thread counts depend on the WIZ hashing
	 * disable bit, which we don't touch here, but it's good
	 * to keep in mind (see 3DSTATE_PS and 3DSTATE_WM).
	 */
	WA_SET_FIELD_MASKED(GEN7_GT_MODE,
			    GEN6_WIZ_HASHING_MASK,
			    GEN6_WIZ_HASHING_16x4);

	return 0;
}

static int bdw_init_workarounds(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;
	int ret;

	ret = gen8_init_workarounds(engine);
	if (ret)
		return ret;

	/* WaDisableThreadStallDopClockGating:bdw (pre-production) */
	WA_SET_BIT_MASKED(GEN8_ROW_CHICKEN, STALL_DOP_GATING_DISABLE);

	/* WaDisableDopClockGating:bdw */
	WA_SET_BIT_MASKED(GEN7_ROW_CHICKEN2,
			  DOP_CLOCK_GATING_DISABLE);

	WA_SET_BIT_MASKED(HALF_SLICE_CHICKEN3,
			  GEN8_SAMPLER_POWER_BYPASS_DIS);

	WA_SET_BIT_MASKED(HDC_CHICKEN0,
			  /* WaForceContextSaveRestoreNonCoherent:bdw */
			  HDC_FORCE_CONTEXT_SAVE_RESTORE_NON_COHERENT |
			  /* WaDisableFenceDestinationToSLM:bdw (pre-prod) */
			  (IS_BDW_GT3(dev_priv) ? HDC_FENCE_DEST_SLM_DISABLE : 0));

	return 0;
}

static int chv_init_workarounds(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;
	int ret;

	ret = gen8_init_workarounds(engine);
	if (ret)
		return ret;

	/* WaDisableThreadStallDopClockGating:chv */
	WA_SET_BIT_MASKED(GEN8_ROW_CHICKEN, STALL_DOP_GATING_DISABLE);

	/* Improve HiZ throughput on CHV. */
	WA_SET_BIT_MASKED(HIZ_CHICKEN, CHV_HZ_8X8_MODE_IN_1X);

	return 0;
}

static int gen9_init_workarounds(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;
	int ret;

	/* WaConextSwitchWithConcurrentTLBInvalidate:skl,bxt,kbl */
	I915_WRITE(GEN9_CSFE_CHICKEN1_RCS, _MASKED_BIT_ENABLE(GEN9_PREEMPT_GPGPU_SYNC_SWITCH_DISABLE));

	/* WaEnableLbsSlaRetryTimerDecrement:skl,bxt,kbl */
	I915_WRITE(BDW_SCRATCH1, I915_READ(BDW_SCRATCH1) |
		   GEN9_LBS_SLA_RETRY_TIMER_DECREMENT_ENABLE);

	/* WaDisableKillLogic:bxt,skl,kbl */
	I915_WRITE(GAM_ECOCHK, I915_READ(GAM_ECOCHK) |
		   ECOCHK_DIS_TLB);

	/* WaClearFlowControlGpgpuContextSave:skl,bxt,kbl */
	/* WaDisablePartialInstShootdown:skl,bxt,kbl */
	WA_SET_BIT_MASKED(GEN8_ROW_CHICKEN,
			  FLOW_CONTROL_ENABLE |
			  PARTIAL_INSTRUCTION_SHOOTDOWN_DISABLE);

	/* Syncing dependencies between camera and graphics:skl,bxt,kbl */
	WA_SET_BIT_MASKED(HALF_SLICE_CHICKEN3,
			  GEN9_DISABLE_OCL_OOB_SUPPRESS_LOGIC);

	/* WaDisableDgMirrorFixInHalfSliceChicken5:skl,bxt */
	if (IS_SKL_REVID(dev_priv, 0, SKL_REVID_B0) ||
	    IS_BXT_REVID(dev_priv, 0, BXT_REVID_A1))
		WA_CLR_BIT_MASKED(GEN9_HALF_SLICE_CHICKEN5,
				  GEN9_DG_MIRROR_FIX_ENABLE);

	/* WaSetDisablePixMaskCammingAndRhwoInCommonSliceChicken:skl,bxt */
	if (IS_SKL_REVID(dev_priv, 0, SKL_REVID_B0) ||
	    IS_BXT_REVID(dev_priv, 0, BXT_REVID_A1)) {
		WA_SET_BIT_MASKED(GEN7_COMMON_SLICE_CHICKEN1,
				  GEN9_RHWO_OPTIMIZATION_DISABLE);
		/*
		 * WA also requires GEN9_SLICE_COMMON_ECO_CHICKEN0[14:14] to be set
		 * but we do that in per ctx batchbuffer as there is an issue
		 * with this register not getting restored on ctx restore
		 */
	}

	/* WaEnableYV12BugFixInHalfSliceChicken7:skl,bxt,kbl */
	/* WaEnableSamplerGPGPUPreemptionSupport:skl,bxt,kbl */
	WA_SET_BIT_MASKED(GEN9_HALF_SLICE_CHICKEN7,
			  GEN9_ENABLE_YV12_BUGFIX |
			  GEN9_ENABLE_GPGPU_PREEMPTION);

	/* Wa4x4STCOptimizationDisable:skl,bxt,kbl */
	/* WaDisablePartialResolveInVc:skl,bxt,kbl */
	WA_SET_BIT_MASKED(CACHE_MODE_1, (GEN8_4x4_STC_OPTIMIZATION_DISABLE |
					 GEN9_PARTIAL_RESOLVE_IN_VC_DISABLE));

	/* WaCcsTlbPrefetchDisable:skl,bxt,kbl */
	WA_CLR_BIT_MASKED(GEN9_HALF_SLICE_CHICKEN5,
			  GEN9_CCS_TLB_PREFETCH_ENABLE);

	/* WaDisableMaskBasedCammingInRCC:skl,bxt */
	if (IS_SKL_REVID(dev_priv, SKL_REVID_C0, SKL_REVID_C0) ||
	    IS_BXT_REVID(dev_priv, 0, BXT_REVID_A1))
		WA_SET_BIT_MASKED(SLICE_ECO_CHICKEN0,
				  PIXEL_MASK_CAMMING_DISABLE);

	/* WaForceContextSaveRestoreNonCoherent:skl,bxt,kbl */
	WA_SET_BIT_MASKED(HDC_CHICKEN0,
			  HDC_FORCE_CONTEXT_SAVE_RESTORE_NON_COHERENT |
			  HDC_FORCE_CSR_NON_COHERENT_OVR_DISABLE);

	/* WaForceEnableNonCoherent and WaDisableHDCInvalidation are
	 * both tied to WaForceContextSaveRestoreNonCoherent
	 * in some hsds for skl. We keep the tie for all gen9. The
	 * documentation is a bit hazy and so we want to get common behaviour,
	 * even though there is no clear evidence we would need both on kbl/bxt.
	 * This area has been source of system hangs so we play it safe
	 * and mimic the skl regardless of what bspec says.
	 *
	 * Use Force Non-Coherent whenever executing a 3D context. This
	 * is a workaround for a possible hang in the unlikely event
	 * a TLB invalidation occurs during a PSD flush.
	 */

	/* WaForceEnableNonCoherent:skl,bxt,kbl */
	WA_SET_BIT_MASKED(HDC_CHICKEN0,
			  HDC_FORCE_NON_COHERENT);

	/* WaDisableHDCInvalidation:skl,bxt,kbl */
	I915_WRITE(GAM_ECOCHK, I915_READ(GAM_ECOCHK) |
		   BDW_DISABLE_HDC_INVALIDATION);

	/* WaDisableSamplerPowerBypassForSOPingPong:skl,bxt,kbl */
	if (IS_SKYLAKE(dev_priv) ||
	    IS_KABYLAKE(dev_priv) ||
	    IS_BXT_REVID(dev_priv, 0, BXT_REVID_B0))
		WA_SET_BIT_MASKED(HALF_SLICE_CHICKEN3,
				  GEN8_SAMPLER_POWER_BYPASS_DIS);

	/* WaDisableSTUnitPowerOptimization:skl,bxt,kbl */
	WA_SET_BIT_MASKED(HALF_SLICE_CHICKEN2, GEN8_ST_PO_DISABLE);

	/* WaOCLCoherentLineFlush:skl,bxt,kbl */
	I915_WRITE(GEN8_L3SQCREG4, (I915_READ(GEN8_L3SQCREG4) |
				    GEN8_LQSC_FLUSH_COHERENT_LINES));

	/* WaVFEStateAfterPipeControlwithMediaStateClear:skl,bxt */
	ret = wa_ring_whitelist_reg(engine, GEN9_CTX_PREEMPT_REG);
	if (ret)
		return ret;

	/* WaEnablePreemptionGranularityControlByUMD:skl,bxt,kbl */
	ret= wa_ring_whitelist_reg(engine, GEN8_CS_CHICKEN1);
	if (ret)
		return ret;

	/* WaAllowUMDToModifyHDCChicken1:skl,bxt,kbl */
	ret = wa_ring_whitelist_reg(engine, GEN8_HDC_CHICKEN1);
	if (ret)
		return ret;

	return 0;
}

static int skl_tune_iz_hashing(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;
	u8 vals[3] = { 0, 0, 0 };
	unsigned int i;

	for (i = 0; i < 3; i++) {
		u8 ss;

		/*
		 * Only consider slices where one, and only one, subslice has 7
		 * EUs
		 */
		if (!is_power_of_2(dev_priv->info.subslice_7eu[i]))
			continue;

		/*
		 * subslice_7eu[i] != 0 (because of the check above) and
		 * ss_max == 4 (maximum number of subslices possible per slice)
		 *
		 * ->    0 <= ss <= 3;
		 */
		ss = ffs(dev_priv->info.subslice_7eu[i]) - 1;
		vals[i] = 3 - ss;
	}

	if (vals[0] == 0 && vals[1] == 0 && vals[2] == 0)
		return 0;

	/* Tune IZ hashing. See intel_device_info_runtime_init() */
	WA_SET_FIELD_MASKED(GEN7_GT_MODE,
			    GEN9_IZ_HASHING_MASK(2) |
			    GEN9_IZ_HASHING_MASK(1) |
			    GEN9_IZ_HASHING_MASK(0),
			    GEN9_IZ_HASHING(2, vals[2]) |
			    GEN9_IZ_HASHING(1, vals[1]) |
			    GEN9_IZ_HASHING(0, vals[0]));

	return 0;
}

static int skl_init_workarounds(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;
	int ret;

	ret = gen9_init_workarounds(engine);
	if (ret)
		return ret;

	/*
	 * Actual WA is to disable percontext preemption granularity control
	 * until D0 which is the default case so this is equivalent to
	 * !WaDisablePerCtxtPreemptionGranularityControl:skl
	 */
	if (IS_SKL_REVID(dev_priv, SKL_REVID_E0, REVID_FOREVER)) {
		I915_WRITE(GEN7_FF_SLICE_CS_CHICKEN1,
			   _MASKED_BIT_ENABLE(GEN9_FFSC_PERCTX_PREEMPT_CTRL));
	}

	if (IS_SKL_REVID(dev_priv, 0, SKL_REVID_E0)) {
		/* WaDisableChickenBitTSGBarrierAckForFFSliceCS:skl */
		I915_WRITE(FF_SLICE_CS_CHICKEN2,
			   _MASKED_BIT_ENABLE(GEN9_TSG_BARRIER_ACK_DISABLE));
	}

	/* GEN8_L3SQCREG4 has a dependency with WA batch so any new changes
	 * involving this register should also be added to WA batch as required.
	 */
	if (IS_SKL_REVID(dev_priv, 0, SKL_REVID_E0))
		/* WaDisableLSQCROPERFforOCL:skl */
		I915_WRITE(GEN8_L3SQCREG4, I915_READ(GEN8_L3SQCREG4) |
			   GEN8_LQSC_RO_PERF_DIS);

	/* WaEnableGapsTsvCreditFix:skl */
	if (IS_SKL_REVID(dev_priv, SKL_REVID_C0, REVID_FOREVER)) {
		I915_WRITE(GEN8_GARBCNTL, (I915_READ(GEN8_GARBCNTL) |
					   GEN9_GAPS_TSV_CREDIT_DISABLE));
	}

	/* WaDisablePowerCompilerClockGating:skl */
	if (IS_SKL_REVID(dev_priv, SKL_REVID_B0, SKL_REVID_B0))
		WA_SET_BIT_MASKED(HIZ_CHICKEN,
				  BDW_HIZ_POWER_COMPILER_CLOCK_GATING_DISABLE);

	/* WaBarrierPerformanceFixDisable:skl */
	if (IS_SKL_REVID(dev_priv, SKL_REVID_C0, SKL_REVID_D0))
		WA_SET_BIT_MASKED(HDC_CHICKEN0,
				  HDC_FENCE_DEST_SLM_DISABLE |
				  HDC_BARRIER_PERFORMANCE_DISABLE);

	/* WaDisableSbeCacheDispatchPortSharing:skl */
	if (IS_SKL_REVID(dev_priv, 0, SKL_REVID_F0))
		WA_SET_BIT_MASKED(
			GEN7_HALF_SLICE_CHICKEN1,
			GEN7_SBE_SS_CACHE_DISPATCH_PORT_SHARING_DISABLE);

	/* WaDisableGafsUnitClkGating:skl */
	WA_SET_BIT(GEN7_UCGCTL4, GEN8_EU_GAUNIT_CLOCK_GATE_DISABLE);

	/* WaInPlaceDecompressionHang:skl */
	if (IS_SKL_REVID(dev_priv, SKL_REVID_H0, REVID_FOREVER))
		WA_SET_BIT(GEN9_GAMT_ECO_REG_RW_IA,
			   GAMT_ECO_ENABLE_IN_PLACE_DECOMPRESS);

	/* WaDisableLSQCROPERFforOCL:skl */
	ret = wa_ring_whitelist_reg(engine, GEN8_L3SQCREG4);
	if (ret)
		return ret;

	return skl_tune_iz_hashing(engine);
}

static int bxt_init_workarounds(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;
	int ret;

	ret = gen9_init_workarounds(engine);
	if (ret)
		return ret;

	/* WaStoreMultiplePTEenable:bxt */
	/* This is a requirement according to Hardware specification */
	if (IS_BXT_REVID(dev_priv, 0, BXT_REVID_A1))
		I915_WRITE(TILECTL, I915_READ(TILECTL) | TILECTL_TLBPF);

	/* WaSetClckGatingDisableMedia:bxt */
	if (IS_BXT_REVID(dev_priv, 0, BXT_REVID_A1)) {
		I915_WRITE(GEN7_MISCCPCTL, (I915_READ(GEN7_MISCCPCTL) &
					    ~GEN8_DOP_CLOCK_GATE_MEDIA_ENABLE));
	}

	/* WaDisableThreadStallDopClockGating:bxt */
	WA_SET_BIT_MASKED(GEN8_ROW_CHICKEN,
			  STALL_DOP_GATING_DISABLE);

	/* WaDisablePooledEuLoadBalancingFix:bxt */
	if (IS_BXT_REVID(dev_priv, BXT_REVID_B0, REVID_FOREVER)) {
		WA_SET_BIT_MASKED(FF_SLICE_CS_CHICKEN2,
				  GEN9_POOLED_EU_LOAD_BALANCING_FIX_DISABLE);
	}

	/* WaDisableSbeCacheDispatchPortSharing:bxt */
	if (IS_BXT_REVID(dev_priv, 0, BXT_REVID_B0)) {
		WA_SET_BIT_MASKED(
			GEN7_HALF_SLICE_CHICKEN1,
			GEN7_SBE_SS_CACHE_DISPATCH_PORT_SHARING_DISABLE);
	}

	/* WaDisableObjectLevelPreemptionForTrifanOrPolygon:bxt */
	/* WaDisableObjectLevelPreemptionForInstancedDraw:bxt */
	/* WaDisableObjectLevelPreemtionForInstanceId:bxt */
	/* WaDisableLSQCROPERFforOCL:bxt */
	if (IS_BXT_REVID(dev_priv, 0, BXT_REVID_A1)) {
		ret = wa_ring_whitelist_reg(engine, GEN9_CS_DEBUG_MODE1);
		if (ret)
			return ret;

		ret = wa_ring_whitelist_reg(engine, GEN8_L3SQCREG4);
		if (ret)
			return ret;
	}

	/* WaProgramL3SqcReg1DefaultForPerf:bxt */
	if (IS_BXT_REVID(dev_priv, BXT_REVID_B0, REVID_FOREVER))
		I915_WRITE(GEN8_L3SQCREG1, L3_GENERAL_PRIO_CREDITS(62) |
					   L3_HIGH_PRIO_CREDITS(2));

	/* WaInsertDummyPushConstPs:bxt */
	if (IS_BXT_REVID(dev_priv, 0, BXT_REVID_B0))
		WA_SET_BIT_MASKED(COMMON_SLICE_CHICKEN2,
				  GEN8_SBE_DISABLE_REPLAY_BUF_OPTIMIZATION);

	/* WaInPlaceDecompressionHang:bxt */
	if (IS_BXT_REVID(dev_priv, BXT_REVID_C0, REVID_FOREVER))
		WA_SET_BIT(GEN9_GAMT_ECO_REG_RW_IA,
			   GAMT_ECO_ENABLE_IN_PLACE_DECOMPRESS);

	return 0;
}

static int kbl_init_workarounds(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;
	int ret;

	ret = gen9_init_workarounds(engine);
	if (ret)
		return ret;

	/* WaEnableGapsTsvCreditFix:kbl */
	I915_WRITE(GEN8_GARBCNTL, (I915_READ(GEN8_GARBCNTL) |
				   GEN9_GAPS_TSV_CREDIT_DISABLE));

	/* WaDisableDynamicCreditSharing:kbl */
	if (IS_KBL_REVID(dev_priv, 0, KBL_REVID_B0))
		WA_SET_BIT(GAMT_CHKN_BIT_REG,
			   GAMT_CHKN_DISABLE_DYNAMIC_CREDIT_SHARING);

	/* WaDisableFenceDestinationToSLM:kbl (pre-prod) */
	if (IS_KBL_REVID(dev_priv, KBL_REVID_A0, KBL_REVID_A0))
		WA_SET_BIT_MASKED(HDC_CHICKEN0,
				  HDC_FENCE_DEST_SLM_DISABLE);

	/* GEN8_L3SQCREG4 has a dependency with WA batch so any new changes
	 * involving this register should also be added to WA batch as required.
	 */
	if (IS_KBL_REVID(dev_priv, 0, KBL_REVID_E0))
		/* WaDisableLSQCROPERFforOCL:kbl */
		I915_WRITE(GEN8_L3SQCREG4, I915_READ(GEN8_L3SQCREG4) |
			   GEN8_LQSC_RO_PERF_DIS);

	/* WaInsertDummyPushConstPs:kbl */
	if (IS_KBL_REVID(dev_priv, 0, KBL_REVID_B0))
		WA_SET_BIT_MASKED(COMMON_SLICE_CHICKEN2,
				  GEN8_SBE_DISABLE_REPLAY_BUF_OPTIMIZATION);

	/* WaDisableGafsUnitClkGating:kbl */
	WA_SET_BIT(GEN7_UCGCTL4, GEN8_EU_GAUNIT_CLOCK_GATE_DISABLE);

	/* WaDisableSbeCacheDispatchPortSharing:kbl */
	WA_SET_BIT_MASKED(
		GEN7_HALF_SLICE_CHICKEN1,
		GEN7_SBE_SS_CACHE_DISPATCH_PORT_SHARING_DISABLE);

	/* WaInPlaceDecompressionHang:kbl */
	WA_SET_BIT(GEN9_GAMT_ECO_REG_RW_IA,
		   GAMT_ECO_ENABLE_IN_PLACE_DECOMPRESS);

	/* WaDisableLSQCROPERFforOCL:kbl */
	ret = wa_ring_whitelist_reg(engine, GEN8_L3SQCREG4);
	if (ret)
		return ret;

	return 0;
}

int init_workarounds_ring(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;

	WARN_ON(engine->id != RCS);

	dev_priv->workarounds.count = 0;
	dev_priv->workarounds.hw_whitelist_count[RCS] = 0;

	if (IS_BROADWELL(dev_priv))
		return bdw_init_workarounds(engine);

	if (IS_CHERRYVIEW(dev_priv))
		return chv_init_workarounds(engine);

	if (IS_SKYLAKE(dev_priv))
		return skl_init_workarounds(engine);

	if (IS_BROXTON(dev_priv))
		return bxt_init_workarounds(engine);

	if (IS_KABYLAKE(dev_priv))
		return kbl_init_workarounds(engine);

	return 0;
}

static int init_render_ring(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;
	int ret = init_ring_common(engine);
	if (ret)
		return ret;

	/* WaTimedSingleVertexDispatch:cl,bw,ctg,elk,ilk,snb */
	if (IS_GEN(dev_priv, 4, 6))
		I915_WRITE(MI_MODE, _MASKED_BIT_ENABLE(VS_TIMER_DISPATCH));

	/* We need to disable the AsyncFlip performance optimisations in order
	 * to use MI_WAIT_FOR_EVENT within the CS. It should already be
	 * programmed to '1' on all products.
	 *
	 * WaDisableAsyncFlipPerfMode:snb,ivb,hsw,vlv
	 */
	if (IS_GEN(dev_priv, 6, 7))
		I915_WRITE(MI_MODE, _MASKED_BIT_ENABLE(ASYNC_FLIP_PERF_DISABLE));

	/* Required for the hardware to program scanline values for waiting */
	/* WaEnableFlushTlbInvalidationMode:snb */
	if (IS_GEN6(dev_priv))
		I915_WRITE(GFX_MODE,
			   _MASKED_BIT_ENABLE(GFX_TLB_INVALIDATE_EXPLICIT));

	/* WaBCSVCSTlbInvalidationMode:ivb,vlv,hsw */
	if (IS_GEN7(dev_priv))
		I915_WRITE(GFX_MODE_GEN7,
			   _MASKED_BIT_ENABLE(GFX_TLB_INVALIDATE_EXPLICIT) |
			   _MASKED_BIT_ENABLE(GFX_REPLAY_MODE));

	if (IS_GEN6(dev_priv)) {
		/* From the Sandybridge PRM, volume 1 part 3, page 24:
		 * "If this bit is set, STCunit will have LRA as replacement
		 *  policy. [...] This bit must be reset.  LRA replacement
		 *  policy is not supported."
		 */
		I915_WRITE(CACHE_MODE_0,
			   _MASKED_BIT_DISABLE(CM0_STC_EVICT_DISABLE_LRA_SNB));
	}

	if (IS_GEN(dev_priv, 6, 7))
		I915_WRITE(INSTPM, _MASKED_BIT_ENABLE(INSTPM_FORCE_ORDERING));

	if (INTEL_INFO(dev_priv)->gen >= 6)
		I915_WRITE_IMR(engine, ~engine->irq_keep_mask);

	return init_workarounds_ring(engine);
}

static void render_ring_cleanup(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;

	if (dev_priv->semaphore_obj) {
		i915_gem_object_ggtt_unpin(dev_priv->semaphore_obj);
		i915_gem_object_put(dev_priv->semaphore_obj);
		dev_priv->semaphore_obj = NULL;
	}

	intel_fini_pipe_control(engine);
}

static int gen8_rcs_signal(struct drm_i915_gem_request *signaller_req,
			   unsigned int num_dwords)
{
#define MBOX_UPDATE_DWORDS 8
	struct intel_engine_cs *signaller = signaller_req->engine;
	struct drm_i915_private *dev_priv = signaller_req->i915;
	struct intel_engine_cs *waiter;
	enum intel_engine_id id;
	int ret, num_rings;

	num_rings = hweight32(INTEL_INFO(dev_priv)->ring_mask);
	num_dwords += (num_rings-1) * MBOX_UPDATE_DWORDS;
#undef MBOX_UPDATE_DWORDS

	ret = intel_ring_begin(signaller_req, num_dwords);
	if (ret)
		return ret;

	for_each_engine_id(waiter, dev_priv, id) {
		u64 gtt_offset = signaller->semaphore.signal_ggtt[id];
		if (gtt_offset == MI_SEMAPHORE_SYNC_INVALID)
			continue;

		intel_ring_emit(signaller, GFX_OP_PIPE_CONTROL(6));
		intel_ring_emit(signaller, PIPE_CONTROL_GLOBAL_GTT_IVB |
					   PIPE_CONTROL_QW_WRITE |
					   PIPE_CONTROL_CS_STALL);
		intel_ring_emit(signaller, lower_32_bits(gtt_offset));
		intel_ring_emit(signaller, upper_32_bits(gtt_offset));
		intel_ring_emit(signaller, signaller_req->fence.seqno);
		intel_ring_emit(signaller, 0);
		intel_ring_emit(signaller, MI_SEMAPHORE_SIGNAL |
					   MI_SEMAPHORE_TARGET(waiter->hw_id));
		intel_ring_emit(signaller, 0);
	}

	return 0;
}

static int gen8_xcs_signal(struct drm_i915_gem_request *signaller_req,
			   unsigned int num_dwords)
{
#define MBOX_UPDATE_DWORDS 6
	struct intel_engine_cs *signaller = signaller_req->engine;
	struct drm_i915_private *dev_priv = signaller_req->i915;
	struct intel_engine_cs *waiter;
	enum intel_engine_id id;
	int ret, num_rings;

	num_rings = hweight32(INTEL_INFO(dev_priv)->ring_mask);
	num_dwords += (num_rings-1) * MBOX_UPDATE_DWORDS;
#undef MBOX_UPDATE_DWORDS

	ret = intel_ring_begin(signaller_req, num_dwords);
	if (ret)
		return ret;

	for_each_engine_id(waiter, dev_priv, id) {
		u64 gtt_offset = signaller->semaphore.signal_ggtt[id];
		if (gtt_offset == MI_SEMAPHORE_SYNC_INVALID)
			continue;

		intel_ring_emit(signaller, (MI_FLUSH_DW + 1) |
					   MI_FLUSH_DW_OP_STOREDW);
		intel_ring_emit(signaller, lower_32_bits(gtt_offset) |
					   MI_FLUSH_DW_USE_GTT);
		intel_ring_emit(signaller, upper_32_bits(gtt_offset));
		intel_ring_emit(signaller, signaller_req->fence.seqno);
		intel_ring_emit(signaller, MI_SEMAPHORE_SIGNAL |
					   MI_SEMAPHORE_TARGET(waiter->hw_id));
		intel_ring_emit(signaller, 0);
	}

	return 0;
}

static int gen6_signal(struct drm_i915_gem_request *signaller_req,
		       unsigned int num_dwords)
{
	struct intel_engine_cs *signaller = signaller_req->engine;
	struct drm_i915_private *dev_priv = signaller_req->i915;
	struct intel_engine_cs *useless;
	enum intel_engine_id id;
	int ret, num_rings;

#define MBOX_UPDATE_DWORDS 3
	num_rings = hweight32(INTEL_INFO(dev_priv)->ring_mask);
	num_dwords += round_up((num_rings-1) * MBOX_UPDATE_DWORDS, 2);
#undef MBOX_UPDATE_DWORDS

	ret = intel_ring_begin(signaller_req, num_dwords);
	if (ret)
		return ret;

	for_each_engine_id(useless, dev_priv, id) {
		i915_reg_t mbox_reg = signaller->semaphore.mbox.signal[id];

		if (i915_mmio_reg_valid(mbox_reg)) {
			intel_ring_emit(signaller, MI_LOAD_REGISTER_IMM(1));
			intel_ring_emit_reg(signaller, mbox_reg);
			intel_ring_emit(signaller, signaller_req->fence.seqno);
		}
	}

	/* If num_dwords was rounded, make sure the tail pointer is correct */
	if (num_rings % 2 == 0)
		intel_ring_emit(signaller, MI_NOOP);

	return 0;
}

/**
 * gen6_add_request - Update the semaphore mailbox registers
 *
 * @request - request to write to the ring
 *
 * Update the mailbox registers in the *other* rings with the current seqno.
 * This acts like a signal in the canonical semaphore.
 */
static int
gen6_add_request(struct drm_i915_gem_request *req)
{
	struct intel_engine_cs *engine = req->engine;
	int ret;

	if (engine->semaphore.signal)
		ret = engine->semaphore.signal(req, 4);
	else
		ret = intel_ring_begin(req, 4);

	if (ret)
		return ret;

	intel_ring_emit(engine, MI_STORE_DWORD_INDEX);
	intel_ring_emit(engine,
			I915_GEM_HWS_INDEX << MI_STORE_DWORD_INDEX_SHIFT);
	intel_ring_emit(engine, req->fence.seqno);
	intel_ring_emit(engine, MI_USER_INTERRUPT);
	__intel_ring_advance(engine);

	return 0;
}

static int
gen8_render_add_request(struct drm_i915_gem_request *req)
{
	struct intel_engine_cs *engine = req->engine;
	int ret;

	if (engine->semaphore.signal)
		ret = engine->semaphore.signal(req, 8);
	else
		ret = intel_ring_begin(req, 8);
	if (ret)
		return ret;

	intel_ring_emit(engine, GFX_OP_PIPE_CONTROL(6));
	intel_ring_emit(engine, (PIPE_CONTROL_GLOBAL_GTT_IVB |
				 PIPE_CONTROL_CS_STALL |
				 PIPE_CONTROL_QW_WRITE));
	intel_ring_emit(engine, intel_hws_seqno_address(req->engine));
	intel_ring_emit(engine, 0);
	intel_ring_emit(engine, i915_gem_request_get_seqno(req));
	/* We're thrashing one dword of HWS. */
	intel_ring_emit(engine, 0);
	intel_ring_emit(engine, MI_USER_INTERRUPT);
	intel_ring_emit(engine, MI_NOOP);
	__intel_ring_advance(engine);

	return 0;
}

static inline bool i915_gem_has_seqno_wrapped(struct drm_i915_private *dev_priv,
					      u32 seqno)
{
	return dev_priv->last_seqno < seqno;
}

/**
 * intel_ring_sync - sync the waiter to the signaller on seqno
 *
 * @waiter - ring that is waiting
 * @signaller - ring which has, or will signal
 * @seqno - seqno which the waiter will block on
 */

static int
gen8_ring_sync(struct drm_i915_gem_request *waiter_req,
	       struct intel_engine_cs *signaller,
	       u32 seqno)
{
	struct intel_engine_cs *waiter = waiter_req->engine;
	struct drm_i915_private *dev_priv = waiter_req->i915;
	u64 offset = GEN8_WAIT_OFFSET(waiter, signaller->id);
	struct i915_hw_ppgtt *ppgtt;
	int ret;

	ret = intel_ring_begin(waiter_req, 4);
	if (ret)
		return ret;

	intel_ring_emit(waiter, MI_SEMAPHORE_WAIT |
				MI_SEMAPHORE_GLOBAL_GTT |
				MI_SEMAPHORE_SAD_GTE_SDD);
	intel_ring_emit(waiter, seqno);
	intel_ring_emit(waiter, lower_32_bits(offset));
	intel_ring_emit(waiter, upper_32_bits(offset));
	intel_ring_advance(waiter);

	/* When the !RCS engines idle waiting upon a semaphore, they lose their
	 * pagetables and we must reload them before executing the batch.
	 * We do this on the i915_switch_context() following the wait and
	 * before the dispatch.
	 */
	ppgtt = waiter_req->ctx->ppgtt;
	if (ppgtt && waiter_req->engine->id != RCS)
		ppgtt->pd_dirty_rings |= intel_engine_flag(waiter_req->engine);
	return 0;
}

static int
gen6_ring_sync(struct drm_i915_gem_request *waiter_req,
	       struct intel_engine_cs *signaller,
	       u32 seqno)
{
	struct intel_engine_cs *waiter = waiter_req->engine;
	u32 dw1 = MI_SEMAPHORE_MBOX |
		  MI_SEMAPHORE_COMPARE |
		  MI_SEMAPHORE_REGISTER;
	u32 wait_mbox = signaller->semaphore.mbox.wait[waiter->id];
	int ret;

	/* Throughout all of the GEM code, seqno passed implies our current
	 * seqno is >= the last seqno executed. However for hardware the
	 * comparison is strictly greater than.
	 */
	seqno -= 1;

	WARN_ON(wait_mbox == MI_SEMAPHORE_SYNC_INVALID);

	ret = intel_ring_begin(waiter_req, 4);
	if (ret)
		return ret;

	/* If seqno wrap happened, omit the wait with no-ops */
	if (likely(!i915_gem_has_seqno_wrapped(waiter_req->i915, seqno))) {
		intel_ring_emit(waiter, dw1 | wait_mbox);
		intel_ring_emit(waiter, seqno);
		intel_ring_emit(waiter, 0);
		intel_ring_emit(waiter, MI_NOOP);
	} else {
		intel_ring_emit(waiter, MI_NOOP);
		intel_ring_emit(waiter, MI_NOOP);
		intel_ring_emit(waiter, MI_NOOP);
		intel_ring_emit(waiter, MI_NOOP);
	}
	intel_ring_advance(waiter);

	return 0;
}

static void
gen5_seqno_barrier(struct intel_engine_cs *engine)
{
	/* MI_STORE are internally buffered by the GPU and not flushed
	 * either by MI_FLUSH or SyncFlush or any other combination of
	 * MI commands.
	 *
	 * "Only the submission of the store operation is guaranteed.
	 * The write result will be complete (coherent) some time later
	 * (this is practically a finite period but there is no guaranteed
	 * latency)."
	 *
	 * Empirically, we observe that we need a delay of at least 75us to
	 * be sure that the seqno write is visible by the CPU.
	 */
	usleep_range(125, 250);
}

static void
gen6_seqno_barrier(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;

	/* Workaround to force correct ordering between irq and seqno writes on
	 * ivb (and maybe also on snb) by reading from a CS register (like
	 * ACTHD) before reading the status page.
	 *
	 * Note that this effectively stalls the read by the time it takes to
	 * do a memory transaction, which more or less ensures that the write
	 * from the GPU has sufficient time to invalidate the CPU cacheline.
	 * Alternatively we could delay the interrupt from the CS ring to give
	 * the write time to land, but that would incur a delay after every
	 * batch i.e. much more frequent than a delay when waiting for the
	 * interrupt (with the same net latency).
	 *
	 * Also note that to prevent whole machine hangs on gen7, we have to
	 * take the spinlock to guard against concurrent cacheline access.
	 */
	spin_lock_irq(&dev_priv->uncore.lock);
	POSTING_READ_FW(RING_ACTHD(engine->mmio_base));
	spin_unlock_irq(&dev_priv->uncore.lock);
}

static void
gen5_irq_enable(struct intel_engine_cs *engine)
{
	gen5_enable_gt_irq(engine->i915, engine->irq_enable_mask);
}

static void
gen5_irq_disable(struct intel_engine_cs *engine)
{
	gen5_disable_gt_irq(engine->i915, engine->irq_enable_mask);
}

static void
i9xx_irq_enable(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;

	dev_priv->irq_mask &= ~engine->irq_enable_mask;
	I915_WRITE(IMR, dev_priv->irq_mask);
	POSTING_READ_FW(RING_IMR(engine->mmio_base));
}

static void
i9xx_irq_disable(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;

	dev_priv->irq_mask |= engine->irq_enable_mask;
	I915_WRITE(IMR, dev_priv->irq_mask);
}

static void
i8xx_irq_enable(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;

	dev_priv->irq_mask &= ~engine->irq_enable_mask;
	I915_WRITE16(IMR, dev_priv->irq_mask);
	POSTING_READ16(RING_IMR(engine->mmio_base));
}

static void
i8xx_irq_disable(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;

	dev_priv->irq_mask |= engine->irq_enable_mask;
	I915_WRITE16(IMR, dev_priv->irq_mask);
}

static int
bsd_ring_flush(struct drm_i915_gem_request *req,
	       u32     invalidate_domains,
	       u32     flush_domains)
{
	struct intel_engine_cs *engine = req->engine;
	int ret;

	ret = intel_ring_begin(req, 2);
	if (ret)
		return ret;

	intel_ring_emit(engine, MI_FLUSH);
	intel_ring_emit(engine, MI_NOOP);
	intel_ring_advance(engine);
	return 0;
}

static int
i9xx_add_request(struct drm_i915_gem_request *req)
{
	struct intel_engine_cs *engine = req->engine;
	int ret;

	ret = intel_ring_begin(req, 4);
	if (ret)
		return ret;

	intel_ring_emit(engine, MI_STORE_DWORD_INDEX);
	intel_ring_emit(engine,
			I915_GEM_HWS_INDEX << MI_STORE_DWORD_INDEX_SHIFT);
	intel_ring_emit(engine, req->fence.seqno);
	intel_ring_emit(engine, MI_USER_INTERRUPT);
	__intel_ring_advance(engine);

	return 0;
}

static void
gen6_irq_enable(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;

	I915_WRITE_IMR(engine,
		       ~(engine->irq_enable_mask |
			 engine->irq_keep_mask));
	gen5_enable_gt_irq(dev_priv, engine->irq_enable_mask);
}

static void
gen6_irq_disable(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;

	I915_WRITE_IMR(engine, ~engine->irq_keep_mask);
	gen5_disable_gt_irq(dev_priv, engine->irq_enable_mask);
}

static void
hsw_vebox_irq_enable(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;

	I915_WRITE_IMR(engine, ~engine->irq_enable_mask);
	gen6_enable_pm_irq(dev_priv, engine->irq_enable_mask);
}

static void
hsw_vebox_irq_disable(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;

	I915_WRITE_IMR(engine, ~0);
	gen6_disable_pm_irq(dev_priv, engine->irq_enable_mask);
}

static void
gen8_irq_enable(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;

	I915_WRITE_IMR(engine,
		       ~(engine->irq_enable_mask |
			 engine->irq_keep_mask));
	POSTING_READ_FW(RING_IMR(engine->mmio_base));
}

static void
gen8_irq_disable(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;

	I915_WRITE_IMR(engine, ~engine->irq_keep_mask);
}

static int
i965_dispatch_execbuffer(struct drm_i915_gem_request *req,
			 u64 offset, u32 length,
			 unsigned dispatch_flags)
{
	struct intel_engine_cs *engine = req->engine;
	int ret;

	ret = intel_ring_begin(req, 2);
	if (ret)
		return ret;

	intel_ring_emit(engine,
			MI_BATCH_BUFFER_START |
			MI_BATCH_GTT |
			(dispatch_flags & I915_DISPATCH_SECURE ?
			 0 : MI_BATCH_NON_SECURE_I965));
	intel_ring_emit(engine, offset);
	intel_ring_advance(engine);

	return 0;
}

/* Just userspace ABI convention to limit the wa batch bo to a resonable size */
#define I830_BATCH_LIMIT (256*1024)
#define I830_TLB_ENTRIES (2)
#define I830_WA_SIZE max(I830_TLB_ENTRIES*4096, I830_BATCH_LIMIT)
static int
i830_dispatch_execbuffer(struct drm_i915_gem_request *req,
			 u64 offset, u32 len,
			 unsigned dispatch_flags)
{
	struct intel_engine_cs *engine = req->engine;
	u32 cs_offset = engine->scratch.gtt_offset;
	int ret;

	ret = intel_ring_begin(req, 6);
	if (ret)
		return ret;

	/* Evict the invalid PTE TLBs */
	intel_ring_emit(engine, COLOR_BLT_CMD | BLT_WRITE_RGBA);
	intel_ring_emit(engine, BLT_DEPTH_32 | BLT_ROP_COLOR_COPY | 4096);
	intel_ring_emit(engine, I830_TLB_ENTRIES << 16 | 4); /* load each page */
	intel_ring_emit(engine, cs_offset);
	intel_ring_emit(engine, 0xdeadbeef);
	intel_ring_emit(engine, MI_NOOP);
	intel_ring_advance(engine);

	if ((dispatch_flags & I915_DISPATCH_PINNED) == 0) {
		if (len > I830_BATCH_LIMIT)
			return -ENOSPC;

		ret = intel_ring_begin(req, 6 + 2);
		if (ret)
			return ret;

		/* Blit the batch (which has now all relocs applied) to the
		 * stable batch scratch bo area (so that the CS never
		 * stumbles over its tlb invalidation bug) ...
		 */
		intel_ring_emit(engine, SRC_COPY_BLT_CMD | BLT_WRITE_RGBA);
		intel_ring_emit(engine,
				BLT_DEPTH_32 | BLT_ROP_SRC_COPY | 4096);
		intel_ring_emit(engine, DIV_ROUND_UP(len, 4096) << 16 | 4096);
		intel_ring_emit(engine, cs_offset);
		intel_ring_emit(engine, 4096);
		intel_ring_emit(engine, offset);

		intel_ring_emit(engine, MI_FLUSH);
		intel_ring_emit(engine, MI_NOOP);
		intel_ring_advance(engine);

		/* ... and execute it. */
		offset = cs_offset;
	}

	ret = intel_ring_begin(req, 2);
	if (ret)
		return ret;

	intel_ring_emit(engine, MI_BATCH_BUFFER_START | MI_BATCH_GTT);
	intel_ring_emit(engine, offset | (dispatch_flags & I915_DISPATCH_SECURE ?
					  0 : MI_BATCH_NON_SECURE));
	intel_ring_advance(engine);

	return 0;
}

static int
i915_dispatch_execbuffer(struct drm_i915_gem_request *req,
			 u64 offset, u32 len,
			 unsigned dispatch_flags)
{
	struct intel_engine_cs *engine = req->engine;
	int ret;

	ret = intel_ring_begin(req, 2);
	if (ret)
		return ret;

	intel_ring_emit(engine, MI_BATCH_BUFFER_START | MI_BATCH_GTT);
	intel_ring_emit(engine, offset | (dispatch_flags & I915_DISPATCH_SECURE ?
					  0 : MI_BATCH_NON_SECURE));
	intel_ring_advance(engine);

	return 0;
}

static void cleanup_phys_status_page(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;

	if (!dev_priv->status_page_dmah)
		return;

	drm_pci_free(&dev_priv->drm, dev_priv->status_page_dmah);
	engine->status_page.page_addr = NULL;
}

static void cleanup_status_page(struct intel_engine_cs *engine)
{
	struct drm_i915_gem_object *obj;

	obj = engine->status_page.obj;
	if (obj == NULL)
		return;

	kunmap(sg_page(obj->pages->sgl));
	i915_gem_object_ggtt_unpin(obj);
	i915_gem_object_put(obj);
	engine->status_page.obj = NULL;
}

static int init_status_page(struct intel_engine_cs *engine)
{
	struct drm_i915_gem_object *obj = engine->status_page.obj;

	if (obj == NULL) {
		unsigned flags;
		int ret;

		obj = i915_gem_object_create(&engine->i915->drm, 4096);
		if (IS_ERR(obj)) {
			DRM_ERROR("Failed to allocate status page\n");
			return PTR_ERR(obj);
		}

		ret = i915_gem_object_set_cache_level(obj, I915_CACHE_LLC);
		if (ret)
			goto err_unref;

		flags = 0;
		if (!HAS_LLC(engine->i915))
			/* On g33, we cannot place HWS above 256MiB, so
			 * restrict its pinning to the low mappable arena.
			 * Though this restriction is not documented for
			 * gen4, gen5, or byt, they also behave similarly
			 * and hang if the HWS is placed at the top of the
			 * GTT. To generalise, it appears that all !llc
			 * platforms have issues with us placing the HWS
			 * above the mappable region (even though we never
			 * actualy map it).
			 */
			flags |= PIN_MAPPABLE;
		ret = i915_gem_obj_ggtt_pin(obj, 4096, flags);
		if (ret) {
err_unref:
			i915_gem_object_put(obj);
			return ret;
		}

		engine->status_page.obj = obj;
	}

	engine->status_page.gfx_addr = i915_gem_obj_ggtt_offset(obj);
	engine->status_page.page_addr = kmap(sg_page(obj->pages->sgl));
	memset(engine->status_page.page_addr, 0, PAGE_SIZE);

	DRM_DEBUG_DRIVER("%s hws offset: 0x%08x\n",
			engine->name, engine->status_page.gfx_addr);

	return 0;
}

static int init_phys_status_page(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;

	if (!dev_priv->status_page_dmah) {
		dev_priv->status_page_dmah =
			drm_pci_alloc(&dev_priv->drm, PAGE_SIZE, PAGE_SIZE);
		if (!dev_priv->status_page_dmah)
			return -ENOMEM;
	}

	engine->status_page.page_addr = dev_priv->status_page_dmah->vaddr;
	memset(engine->status_page.page_addr, 0, PAGE_SIZE);

	return 0;
}

void intel_unpin_ringbuffer_obj(struct intel_ringbuffer *ringbuf)
{
	GEM_BUG_ON(!ringbuf->vma);
	GEM_BUG_ON(!ringbuf->vaddr);

	if (HAS_LLC(ringbuf->obj->base.dev) && !ringbuf->obj->stolen)
		i915_gem_object_unpin_map(ringbuf->obj);
	else
		i915_vma_unpin_iomap(ringbuf->vma);
	ringbuf->vaddr = NULL;

	i915_gem_object_ggtt_unpin(ringbuf->obj);
	ringbuf->vma = NULL;
}

int intel_pin_and_map_ringbuffer_obj(struct drm_i915_private *dev_priv,
				     struct intel_ringbuffer *ringbuf)
{
	struct drm_i915_gem_object *obj = ringbuf->obj;
	/* Ring wraparound at offset 0 sometimes hangs. No idea why. */
	unsigned flags = PIN_OFFSET_BIAS | 4096;
	void *addr;
	int ret;

	if (HAS_LLC(dev_priv) && !obj->stolen) {
		ret = i915_gem_obj_ggtt_pin(obj, PAGE_SIZE, flags);
		if (ret)
			return ret;

		ret = i915_gem_object_set_to_cpu_domain(obj, true);
		if (ret)
			goto err_unpin;

		addr = i915_gem_object_pin_map(obj);
		if (IS_ERR(addr)) {
			ret = PTR_ERR(addr);
			goto err_unpin;
		}
	} else {
		ret = i915_gem_obj_ggtt_pin(obj, PAGE_SIZE,
					    flags | PIN_MAPPABLE);
		if (ret)
			return ret;

		ret = i915_gem_object_set_to_gtt_domain(obj, true);
		if (ret)
			goto err_unpin;

		/* Access through the GTT requires the device to be awake. */
		assert_rpm_wakelock_held(dev_priv);

		addr = (void __force *)
			i915_vma_pin_iomap(i915_gem_obj_to_ggtt(obj));
		if (IS_ERR(addr)) {
			ret = PTR_ERR(addr);
			goto err_unpin;
		}
	}

	ringbuf->vaddr = addr;
	ringbuf->vma = i915_gem_obj_to_ggtt(obj);
	return 0;

err_unpin:
	i915_gem_object_ggtt_unpin(obj);
	return ret;
}

static void intel_destroy_ringbuffer_obj(struct intel_ringbuffer *ringbuf)
{
	i915_gem_object_put(ringbuf->obj);
	ringbuf->obj = NULL;
}

static int intel_alloc_ringbuffer_obj(struct drm_device *dev,
				      struct intel_ringbuffer *ringbuf)
{
	struct drm_i915_gem_object *obj;

	obj = NULL;
	if (!HAS_LLC(dev))
		obj = i915_gem_object_create_stolen(dev, ringbuf->size);
	if (obj == NULL)
		obj = i915_gem_object_create(dev, ringbuf->size);
	if (IS_ERR(obj))
		return PTR_ERR(obj);

	/* mark ring buffers as read-only from GPU side by default */
	obj->gt_ro = 1;

	ringbuf->obj = obj;

	return 0;
}

struct intel_ringbuffer *
intel_engine_create_ringbuffer(struct intel_engine_cs *engine, int size)
{
	struct intel_ringbuffer *ring;
	int ret;

	ring = kzalloc(sizeof(*ring), GFP_KERNEL);
	if (ring == NULL) {
		DRM_DEBUG_DRIVER("Failed to allocate ringbuffer %s\n",
				 engine->name);
		return ERR_PTR(-ENOMEM);
	}

	ring->engine = engine;
	list_add(&ring->link, &engine->buffers);

	ring->size = size;
	/* Workaround an erratum on the i830 which causes a hang if
	 * the TAIL pointer points to within the last 2 cachelines
	 * of the buffer.
	 */
	ring->effective_size = size;
	if (IS_I830(engine->i915) || IS_845G(engine->i915))
		ring->effective_size -= 2 * CACHELINE_BYTES;

	ring->last_retired_head = -1;
	intel_ring_update_space(ring);

	ret = intel_alloc_ringbuffer_obj(&engine->i915->drm, ring);
	if (ret) {
		DRM_DEBUG_DRIVER("Failed to allocate ringbuffer %s: %d\n",
				 engine->name, ret);
		list_del(&ring->link);
		kfree(ring);
		return ERR_PTR(ret);
	}

	return ring;
}

void
intel_ringbuffer_free(struct intel_ringbuffer *ring)
{
	intel_destroy_ringbuffer_obj(ring);
	list_del(&ring->link);
	kfree(ring);
}

static int intel_ring_context_pin(struct i915_gem_context *ctx,
				  struct intel_engine_cs *engine)
{
	struct intel_context *ce = &ctx->engine[engine->id];
	int ret;

	lockdep_assert_held(&ctx->i915->drm.struct_mutex);

	if (ce->pin_count++)
		return 0;

	if (ce->state) {
		ret = i915_gem_obj_ggtt_pin(ce->state, ctx->ggtt_alignment, 0);
		if (ret)
			goto error;
	}

	/* The kernel context is only used as a placeholder for flushing the
	 * active context. It is never used for submitting user rendering and
	 * as such never requires the golden render context, and so we can skip
	 * emitting it when we switch to the kernel context. This is required
	 * as during eviction we cannot allocate and pin the renderstate in
	 * order to initialise the context.
	 */
	if (ctx == ctx->i915->kernel_context)
		ce->initialised = true;

	i915_gem_context_get(ctx);
	return 0;

error:
	ce->pin_count = 0;
	return ret;
}

static void intel_ring_context_unpin(struct i915_gem_context *ctx,
				     struct intel_engine_cs *engine)
{
	struct intel_context *ce = &ctx->engine[engine->id];

	lockdep_assert_held(&ctx->i915->drm.struct_mutex);

	if (--ce->pin_count)
		return;

	if (ce->state)
		i915_gem_object_ggtt_unpin(ce->state);

	i915_gem_context_put(ctx);
}

static int intel_init_ring_buffer(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;
	struct intel_ringbuffer *ringbuf;
	int ret;

	WARN_ON(engine->buffer);

	intel_engine_setup_common(engine);

	memset(engine->semaphore.sync_seqno, 0,
	       sizeof(engine->semaphore.sync_seqno));

	ret = intel_engine_init_common(engine);
	if (ret)
		goto error;

	/* We may need to do things with the shrinker which
	 * require us to immediately switch back to the default
	 * context. This can cause a problem as pinning the
	 * default context also requires GTT space which may not
	 * be available. To avoid this we always pin the default
	 * context.
	 */
	ret = intel_ring_context_pin(dev_priv->kernel_context, engine);
	if (ret)
		goto error;

	ringbuf = intel_engine_create_ringbuffer(engine, 32 * PAGE_SIZE);
	if (IS_ERR(ringbuf)) {
		ret = PTR_ERR(ringbuf);
		goto error;
	}
	engine->buffer = ringbuf;

	if (I915_NEED_GFX_HWS(dev_priv)) {
		ret = init_status_page(engine);
		if (ret)
			goto error;
	} else {
		WARN_ON(engine->id != RCS);
		ret = init_phys_status_page(engine);
		if (ret)
			goto error;
	}

	ret = intel_pin_and_map_ringbuffer_obj(dev_priv, ringbuf);
	if (ret) {
		DRM_ERROR("Failed to pin and map ringbuffer %s: %d\n",
				engine->name, ret);
		intel_destroy_ringbuffer_obj(ringbuf);
		goto error;
	}

	return 0;

error:
	intel_cleanup_engine(engine);
	return ret;
}

void intel_cleanup_engine(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv;

	if (!intel_engine_initialized(engine))
		return;

	dev_priv = engine->i915;

	if (engine->buffer) {
		intel_stop_engine(engine);
		WARN_ON(!IS_GEN2(dev_priv) && (I915_READ_MODE(engine) & MODE_IDLE) == 0);

		intel_unpin_ringbuffer_obj(engine->buffer);
		intel_ringbuffer_free(engine->buffer);
		engine->buffer = NULL;
	}

	if (engine->cleanup)
		engine->cleanup(engine);

	if (I915_NEED_GFX_HWS(dev_priv)) {
		cleanup_status_page(engine);
	} else {
		WARN_ON(engine->id != RCS);
		cleanup_phys_status_page(engine);
	}

	i915_cmd_parser_fini_ring(engine);
	i915_gem_batch_pool_fini(&engine->batch_pool);
	intel_engine_fini_breadcrumbs(engine);

	intel_ring_context_unpin(dev_priv->kernel_context, engine);

	engine->i915 = NULL;
}

int intel_engine_idle(struct intel_engine_cs *engine)
{
	struct drm_i915_gem_request *req;

	/* Wait upon the last request to be completed */
	if (list_empty(&engine->request_list))
		return 0;

	req = list_entry(engine->request_list.prev,
			 struct drm_i915_gem_request,
			 list);

	/* Make sure we do not trigger any retires */
	return __i915_wait_request(req,
				   req->i915->mm.interruptible,
				   NULL, NULL);
}

int intel_ring_alloc_request_extras(struct drm_i915_gem_request *request)
{
	int ret;

	/* Flush enough space to reduce the likelihood of waiting after
	 * we start building the request - in which case we will just
	 * have to repeat work.
	 */
	request->reserved_space += LEGACY_REQUEST_SIZE;

	request->ringbuf = request->engine->buffer;

	ret = intel_ring_begin(request, 0);
	if (ret)
		return ret;

	request->reserved_space -= LEGACY_REQUEST_SIZE;
	return 0;
}

static int wait_for_space(struct drm_i915_gem_request *req, int bytes)
{
	struct intel_ringbuffer *ringbuf = req->ringbuf;
	struct intel_engine_cs *engine = req->engine;
	struct drm_i915_gem_request *target;

	intel_ring_update_space(ringbuf);
	if (ringbuf->space >= bytes)
		return 0;

	/*
	 * Space is reserved in the ringbuffer for finalising the request,
	 * as that cannot be allowed to fail. During request finalisation,
	 * reserved_space is set to 0 to stop the overallocation and the
	 * assumption is that then we never need to wait (which has the
	 * risk of failing with EINTR).
	 *
	 * See also i915_gem_request_alloc() and i915_add_request().
	 */
	GEM_BUG_ON(!req->reserved_space);

	list_for_each_entry(target, &engine->request_list, list) {
		unsigned space;

		/*
		 * The request queue is per-engine, so can contain requests
		 * from multiple ringbuffers. Here, we must ignore any that
		 * aren't from the ringbuffer we're considering.
		 */
		if (target->ringbuf != ringbuf)
			continue;

		/* Would completion of this request free enough space? */
		space = __intel_ring_space(target->postfix, ringbuf->tail,
					   ringbuf->size);
		if (space >= bytes)
			break;
	}

	if (WARN_ON(&target->list == &engine->request_list))
		return -ENOSPC;

	return i915_wait_request(target);
}

int intel_ring_begin(struct drm_i915_gem_request *req, int num_dwords)
{
	struct intel_ringbuffer *ringbuf = req->ringbuf;
	int remain_actual = ringbuf->size - ringbuf->tail;
	int remain_usable = ringbuf->effective_size - ringbuf->tail;
	int bytes = num_dwords * sizeof(u32);
	int total_bytes, wait_bytes;
	bool need_wrap = false;

	total_bytes = bytes + req->reserved_space;

	if (unlikely(bytes > remain_usable)) {
		/*
		 * Not enough space for the basic request. So need to flush
		 * out the remainder and then wait for base + reserved.
		 */
		wait_bytes = remain_actual + total_bytes;
		need_wrap = true;
	} else if (unlikely(total_bytes > remain_usable)) {
		/*
		 * The base request will fit but the reserved space
		 * falls off the end. So we don't need an immediate wrap
		 * and only need to effectively wait for the reserved
		 * size space from the start of ringbuffer.
		 */
		wait_bytes = remain_actual + req->reserved_space;
	} else {
		/* No wrapping required, just waiting. */
		wait_bytes = total_bytes;
	}

	if (wait_bytes > ringbuf->space) {
		int ret = wait_for_space(req, wait_bytes);
		if (unlikely(ret))
			return ret;

		intel_ring_update_space(ringbuf);
		if (unlikely(ringbuf->space < wait_bytes))
			return -EAGAIN;
	}

	if (unlikely(need_wrap)) {
		GEM_BUG_ON(remain_actual > ringbuf->space);
		GEM_BUG_ON(ringbuf->tail + remain_actual > ringbuf->size);

		/* Fill the tail with MI_NOOP */
		memset(ringbuf->vaddr + ringbuf->tail, 0, remain_actual);
		ringbuf->tail = 0;
		ringbuf->space -= remain_actual;
	}

	ringbuf->space -= bytes;
	GEM_BUG_ON(ringbuf->space < 0);
	return 0;
}

/* Align the ring tail to a cacheline boundary */
int intel_ring_cacheline_align(struct drm_i915_gem_request *req)
{
	struct intel_engine_cs *engine = req->engine;
	int num_dwords = (engine->buffer->tail & (CACHELINE_BYTES - 1)) / sizeof(uint32_t);
	int ret;

	if (num_dwords == 0)
		return 0;

	num_dwords = CACHELINE_BYTES / sizeof(uint32_t) - num_dwords;
	ret = intel_ring_begin(req, num_dwords);
	if (ret)
		return ret;

	while (num_dwords--)
		intel_ring_emit(engine, MI_NOOP);

	intel_ring_advance(engine);

	return 0;
}

void intel_ring_init_seqno(struct intel_engine_cs *engine, u32 seqno)
{
	struct drm_i915_private *dev_priv = engine->i915;

	/* Our semaphore implementation is strictly monotonic (i.e. we proceed
	 * so long as the semaphore value in the register/page is greater
	 * than the sync value), so whenever we reset the seqno,
	 * so long as we reset the tracking semaphore value to 0, it will
	 * always be before the next request's seqno. If we don't reset
	 * the semaphore value, then when the seqno moves backwards all
	 * future waits will complete instantly (causing rendering corruption).
	 */
	if (IS_GEN6(dev_priv) || IS_GEN7(dev_priv)) {
		I915_WRITE(RING_SYNC_0(engine->mmio_base), 0);
		I915_WRITE(RING_SYNC_1(engine->mmio_base), 0);
		if (HAS_VEBOX(dev_priv))
			I915_WRITE(RING_SYNC_2(engine->mmio_base), 0);
	}
	if (dev_priv->semaphore_obj) {
		struct drm_i915_gem_object *obj = dev_priv->semaphore_obj;
		struct page *page = i915_gem_object_get_dirty_page(obj, 0);
		void *semaphores = kmap(page);
		memset(semaphores + GEN8_SEMAPHORE_OFFSET(engine->id, 0),
		       0, I915_NUM_ENGINES * gen8_semaphore_seqno_size);
		kunmap(page);
	}
	memset(engine->semaphore.sync_seqno, 0,
	       sizeof(engine->semaphore.sync_seqno));

	intel_write_status_page(engine, I915_GEM_HWS_INDEX, seqno);
	if (engine->irq_seqno_barrier)
		engine->irq_seqno_barrier(engine);
	engine->last_submitted_seqno = seqno;

	engine->hangcheck.seqno = seqno;

	/* After manually advancing the seqno, fake the interrupt in case
	 * there are any waiters for that seqno.
	 */
	rcu_read_lock();
	intel_engine_wakeup(engine);
	rcu_read_unlock();
}

static void gen6_bsd_ring_write_tail(struct intel_engine_cs *engine,
				     u32 value)
{
	struct drm_i915_private *dev_priv = engine->i915;

	intel_uncore_forcewake_get(dev_priv, FORCEWAKE_ALL);

       /* Every tail move must follow the sequence below */

	/* Disable notification that the ring is IDLE. The GT
	 * will then assume that it is busy and bring it out of rc6.
	 */
	I915_WRITE_FW(GEN6_BSD_SLEEP_PSMI_CONTROL,
		      _MASKED_BIT_ENABLE(GEN6_BSD_SLEEP_MSG_DISABLE));

	/* Clear the context id. Here be magic! */
	I915_WRITE64_FW(GEN6_BSD_RNCID, 0x0);

	/* Wait for the ring not to be idle, i.e. for it to wake up. */
	if (intel_wait_for_register_fw(dev_priv,
				       GEN6_BSD_SLEEP_PSMI_CONTROL,
				       GEN6_BSD_SLEEP_INDICATOR,
				       0,
				       50))
		DRM_ERROR("timed out waiting for the BSD ring to wake up\n");

	/* Now that the ring is fully powered up, update the tail */
	I915_WRITE_FW(RING_TAIL(engine->mmio_base), value);
	POSTING_READ_FW(RING_TAIL(engine->mmio_base));

	/* Let the ring send IDLE messages to the GT again,
	 * and so let it sleep to conserve power when idle.
	 */
	I915_WRITE_FW(GEN6_BSD_SLEEP_PSMI_CONTROL,
		      _MASKED_BIT_DISABLE(GEN6_BSD_SLEEP_MSG_DISABLE));

	intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);
}

static int gen6_bsd_ring_flush(struct drm_i915_gem_request *req,
			       u32 invalidate, u32 flush)
{
	struct intel_engine_cs *engine = req->engine;
	uint32_t cmd;
	int ret;

	ret = intel_ring_begin(req, 4);
	if (ret)
		return ret;

	cmd = MI_FLUSH_DW;
	if (INTEL_GEN(req->i915) >= 8)
		cmd += 1;

	/* We always require a command barrier so that subsequent
	 * commands, such as breadcrumb interrupts, are strictly ordered
	 * wrt the contents of the write cache being flushed to memory
	 * (and thus being coherent from the CPU).
	 */
	cmd |= MI_FLUSH_DW_STORE_INDEX | MI_FLUSH_DW_OP_STOREDW;

	/*
	 * Bspec vol 1c.5 - video engine command streamer:
	 * "If ENABLED, all TLBs will be invalidated once the flush
	 * operation is complete. This bit is only valid when the
	 * Post-Sync Operation field is a value of 1h or 3h."
	 */
	if (invalidate & I915_GEM_GPU_DOMAINS)
		cmd |= MI_INVALIDATE_TLB | MI_INVALIDATE_BSD;

	intel_ring_emit(engine, cmd);
	intel_ring_emit(engine,
			I915_GEM_HWS_SCRATCH_ADDR | MI_FLUSH_DW_USE_GTT);
	if (INTEL_GEN(req->i915) >= 8) {
		intel_ring_emit(engine, 0); /* upper addr */
		intel_ring_emit(engine, 0); /* value */
	} else  {
		intel_ring_emit(engine, 0);
		intel_ring_emit(engine, MI_NOOP);
	}
	intel_ring_advance(engine);
	return 0;
}

static int
gen8_ring_dispatch_execbuffer(struct drm_i915_gem_request *req,
			      u64 offset, u32 len,
			      unsigned dispatch_flags)
{
	struct intel_engine_cs *engine = req->engine;
	bool ppgtt = USES_PPGTT(engine->dev) &&
			!(dispatch_flags & I915_DISPATCH_SECURE);
	int ret;

	ret = intel_ring_begin(req, 4);
	if (ret)
		return ret;

	/* FIXME(BDW): Address space and security selectors. */
	intel_ring_emit(engine, MI_BATCH_BUFFER_START_GEN8 | (ppgtt<<8) |
			(dispatch_flags & I915_DISPATCH_RS ?
			 MI_BATCH_RESOURCE_STREAMER : 0));
	intel_ring_emit(engine, lower_32_bits(offset));
	intel_ring_emit(engine, upper_32_bits(offset));
	intel_ring_emit(engine, MI_NOOP);
	intel_ring_advance(engine);

	return 0;
}

static int
hsw_ring_dispatch_execbuffer(struct drm_i915_gem_request *req,
			     u64 offset, u32 len,
			     unsigned dispatch_flags)
{
	struct intel_engine_cs *engine = req->engine;
	int ret;

	ret = intel_ring_begin(req, 2);
	if (ret)
		return ret;

	intel_ring_emit(engine,
			MI_BATCH_BUFFER_START |
			(dispatch_flags & I915_DISPATCH_SECURE ?
			 0 : MI_BATCH_PPGTT_HSW | MI_BATCH_NON_SECURE_HSW) |
			(dispatch_flags & I915_DISPATCH_RS ?
			 MI_BATCH_RESOURCE_STREAMER : 0));
	/* bit0-7 is the length on GEN6+ */
	intel_ring_emit(engine, offset);
	intel_ring_advance(engine);

	return 0;
}

static int
gen6_ring_dispatch_execbuffer(struct drm_i915_gem_request *req,
			      u64 offset, u32 len,
			      unsigned dispatch_flags)
{
	struct intel_engine_cs *engine = req->engine;
	int ret;

	ret = intel_ring_begin(req, 2);
	if (ret)
		return ret;

	intel_ring_emit(engine,
			MI_BATCH_BUFFER_START |
			(dispatch_flags & I915_DISPATCH_SECURE ?
			 0 : MI_BATCH_NON_SECURE_I965));
	/* bit0-7 is the length on GEN6+ */
	intel_ring_emit(engine, offset);
	intel_ring_advance(engine);

	return 0;
}

/* Blitter support (SandyBridge+) */

static int gen6_ring_flush(struct drm_i915_gem_request *req,
			   u32 invalidate, u32 flush)
{
	struct intel_engine_cs *engine = req->engine;
	uint32_t cmd;
	int ret;

	ret = intel_ring_begin(req, 4);
	if (ret)
		return ret;

	cmd = MI_FLUSH_DW;
	if (INTEL_GEN(req->i915) >= 8)
		cmd += 1;

	/* We always require a command barrier so that subsequent
	 * commands, such as breadcrumb interrupts, are strictly ordered
	 * wrt the contents of the write cache being flushed to memory
	 * (and thus being coherent from the CPU).
	 */
	cmd |= MI_FLUSH_DW_STORE_INDEX | MI_FLUSH_DW_OP_STOREDW;

	/*
	 * Bspec vol 1c.3 - blitter engine command streamer:
	 * "If ENABLED, all TLBs will be invalidated once the flush
	 * operation is complete. This bit is only valid when the
	 * Post-Sync Operation field is a value of 1h or 3h."
	 */
	if (invalidate & I915_GEM_DOMAIN_RENDER)
		cmd |= MI_INVALIDATE_TLB;
	intel_ring_emit(engine, cmd);
	intel_ring_emit(engine,
			I915_GEM_HWS_SCRATCH_ADDR | MI_FLUSH_DW_USE_GTT);
	if (INTEL_GEN(req->i915) >= 8) {
		intel_ring_emit(engine, 0); /* upper addr */
		intel_ring_emit(engine, 0); /* value */
	} else  {
		intel_ring_emit(engine, 0);
		intel_ring_emit(engine, MI_NOOP);
	}
	intel_ring_advance(engine);

	return 0;
}

static void intel_ring_init_semaphores(struct drm_i915_private *dev_priv,
				       struct intel_engine_cs *engine)
{
	struct drm_i915_gem_object *obj;
	int ret, i;

	if (!i915.semaphores)
		return;

	if (INTEL_GEN(dev_priv) >= 8 && !dev_priv->semaphore_obj) {
		obj = i915_gem_object_create(&dev_priv->drm, 4096);
		if (IS_ERR(obj)) {
			DRM_ERROR("Failed to allocate semaphore bo. Disabling semaphores\n");
			i915.semaphores = 0;
		} else {
			i915_gem_object_set_cache_level(obj, I915_CACHE_LLC);
			ret = i915_gem_obj_ggtt_pin(obj, 0, PIN_NONBLOCK);
			if (ret != 0) {
				i915_gem_object_put(obj);
				DRM_ERROR("Failed to pin semaphore bo. Disabling semaphores\n");
				i915.semaphores = 0;
			} else {
				dev_priv->semaphore_obj = obj;
			}
		}
	}

	if (!i915.semaphores)
		return;

	if (INTEL_GEN(dev_priv) >= 8) {
		u64 offset = i915_gem_obj_ggtt_offset(dev_priv->semaphore_obj);

		engine->semaphore.sync_to = gen8_ring_sync;
		engine->semaphore.signal = gen8_xcs_signal;

		for (i = 0; i < I915_NUM_ENGINES; i++) {
			u64 ring_offset;

			if (i != engine->id)
				ring_offset = offset + GEN8_SEMAPHORE_OFFSET(engine->id, i);
			else
				ring_offset = MI_SEMAPHORE_SYNC_INVALID;

			engine->semaphore.signal_ggtt[i] = ring_offset;
		}
	} else if (INTEL_GEN(dev_priv) >= 6) {
		engine->semaphore.sync_to = gen6_ring_sync;
		engine->semaphore.signal = gen6_signal;

		/*
		 * The current semaphore is only applied on pre-gen8
		 * platform.  And there is no VCS2 ring on the pre-gen8
		 * platform. So the semaphore between RCS and VCS2 is
		 * initialized as INVALID.  Gen8 will initialize the
		 * sema between VCS2 and RCS later.
		 */
		for (i = 0; i < I915_NUM_ENGINES; i++) {
			static const struct {
				u32 wait_mbox;
				i915_reg_t mbox_reg;
			} sem_data[I915_NUM_ENGINES][I915_NUM_ENGINES] = {
				[RCS] = {
					[VCS] =  { .wait_mbox = MI_SEMAPHORE_SYNC_RV,  .mbox_reg = GEN6_VRSYNC },
					[BCS] =  { .wait_mbox = MI_SEMAPHORE_SYNC_RB,  .mbox_reg = GEN6_BRSYNC },
					[VECS] = { .wait_mbox = MI_SEMAPHORE_SYNC_RVE, .mbox_reg = GEN6_VERSYNC },
				},
				[VCS] = {
					[RCS] =  { .wait_mbox = MI_SEMAPHORE_SYNC_VR,  .mbox_reg = GEN6_RVSYNC },
					[BCS] =  { .wait_mbox = MI_SEMAPHORE_SYNC_VB,  .mbox_reg = GEN6_BVSYNC },
					[VECS] = { .wait_mbox = MI_SEMAPHORE_SYNC_VVE, .mbox_reg = GEN6_VEVSYNC },
				},
				[BCS] = {
					[RCS] =  { .wait_mbox = MI_SEMAPHORE_SYNC_BR,  .mbox_reg = GEN6_RBSYNC },
					[VCS] =  { .wait_mbox = MI_SEMAPHORE_SYNC_BV,  .mbox_reg = GEN6_VBSYNC },
					[VECS] = { .wait_mbox = MI_SEMAPHORE_SYNC_BVE, .mbox_reg = GEN6_VEBSYNC },
				},
				[VECS] = {
					[RCS] =  { .wait_mbox = MI_SEMAPHORE_SYNC_VER, .mbox_reg = GEN6_RVESYNC },
					[VCS] =  { .wait_mbox = MI_SEMAPHORE_SYNC_VEV, .mbox_reg = GEN6_VVESYNC },
					[BCS] =  { .wait_mbox = MI_SEMAPHORE_SYNC_VEB, .mbox_reg = GEN6_BVESYNC },
				},
			};
			u32 wait_mbox;
			i915_reg_t mbox_reg;

			if (i == engine->id || i == VCS2) {
				wait_mbox = MI_SEMAPHORE_SYNC_INVALID;
				mbox_reg = GEN6_NOSYNC;
			} else {
				wait_mbox = sem_data[engine->id][i].wait_mbox;
				mbox_reg = sem_data[engine->id][i].mbox_reg;
			}

			engine->semaphore.mbox.wait[i] = wait_mbox;
			engine->semaphore.mbox.signal[i] = mbox_reg;
		}
	}
}

static void intel_ring_init_irq(struct drm_i915_private *dev_priv,
				struct intel_engine_cs *engine)
{
	engine->irq_enable_mask = GT_RENDER_USER_INTERRUPT << engine->irq_shift;

	if (INTEL_GEN(dev_priv) >= 8) {
		engine->irq_enable = gen8_irq_enable;
		engine->irq_disable = gen8_irq_disable;
		engine->irq_seqno_barrier = gen6_seqno_barrier;
	} else if (INTEL_GEN(dev_priv) >= 6) {
		engine->irq_enable = gen6_irq_enable;
		engine->irq_disable = gen6_irq_disable;
		engine->irq_seqno_barrier = gen6_seqno_barrier;
	} else if (INTEL_GEN(dev_priv) >= 5) {
		engine->irq_enable = gen5_irq_enable;
		engine->irq_disable = gen5_irq_disable;
		engine->irq_seqno_barrier = gen5_seqno_barrier;
	} else if (INTEL_GEN(dev_priv) >= 3) {
		engine->irq_enable = i9xx_irq_enable;
		engine->irq_disable = i9xx_irq_disable;
	} else {
		engine->irq_enable = i8xx_irq_enable;
		engine->irq_disable = i8xx_irq_disable;
	}
}

static void intel_ring_default_vfuncs(struct drm_i915_private *dev_priv,
				      struct intel_engine_cs *engine)
{
	engine->init_hw = init_ring_common;
	engine->write_tail = ring_write_tail;

	engine->add_request = i9xx_add_request;
	if (INTEL_GEN(dev_priv) >= 6)
		engine->add_request = gen6_add_request;

	if (INTEL_GEN(dev_priv) >= 8)
		engine->dispatch_execbuffer = gen8_ring_dispatch_execbuffer;
	else if (INTEL_GEN(dev_priv) >= 6)
		engine->dispatch_execbuffer = gen6_ring_dispatch_execbuffer;
	else if (INTEL_GEN(dev_priv) >= 4)
		engine->dispatch_execbuffer = i965_dispatch_execbuffer;
	else if (IS_I830(dev_priv) || IS_845G(dev_priv))
		engine->dispatch_execbuffer = i830_dispatch_execbuffer;
	else
		engine->dispatch_execbuffer = i915_dispatch_execbuffer;

	intel_ring_init_irq(dev_priv, engine);
	intel_ring_init_semaphores(dev_priv, engine);
}

int intel_init_render_ring_buffer(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;
	int ret;

	intel_ring_default_vfuncs(dev_priv, engine);

	if (HAS_L3_DPF(dev_priv))
		engine->irq_keep_mask = GT_RENDER_L3_PARITY_ERROR_INTERRUPT;

	if (INTEL_GEN(dev_priv) >= 8) {
		engine->init_context = intel_rcs_ctx_init;
		engine->add_request = gen8_render_add_request;
		engine->flush = gen8_render_ring_flush;
		if (i915.semaphores)
			engine->semaphore.signal = gen8_rcs_signal;
	} else if (INTEL_GEN(dev_priv) >= 6) {
		engine->init_context = intel_rcs_ctx_init;
		engine->flush = gen7_render_ring_flush;
		if (IS_GEN6(dev_priv))
			engine->flush = gen6_render_ring_flush;
	} else if (IS_GEN5(dev_priv)) {
		engine->flush = gen4_render_ring_flush;
	} else {
		if (INTEL_GEN(dev_priv) < 4)
			engine->flush = gen2_render_ring_flush;
		else
			engine->flush = gen4_render_ring_flush;
		engine->irq_enable_mask = I915_USER_INTERRUPT;
	}

	if (IS_HASWELL(dev_priv))
		engine->dispatch_execbuffer = hsw_ring_dispatch_execbuffer;

	engine->init_hw = init_render_ring;
	engine->cleanup = render_ring_cleanup;

	ret = intel_init_ring_buffer(engine);
	if (ret)
		return ret;

	if (INTEL_GEN(dev_priv) >= 6) {
		ret = intel_init_pipe_control(engine, 4096);
		if (ret)
			return ret;
	} else if (HAS_BROKEN_CS_TLB(dev_priv)) {
		ret = intel_init_pipe_control(engine, I830_WA_SIZE);
		if (ret)
			return ret;
	}

	return 0;
}

int intel_init_bsd_ring_buffer(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;

	intel_ring_default_vfuncs(dev_priv, engine);

	if (INTEL_GEN(dev_priv) >= 6) {
		/* gen6 bsd needs a special wa for tail updates */
		if (IS_GEN6(dev_priv))
			engine->write_tail = gen6_bsd_ring_write_tail;
		engine->flush = gen6_bsd_ring_flush;
		if (INTEL_GEN(dev_priv) < 8)
			engine->irq_enable_mask = GT_BSD_USER_INTERRUPT;
	} else {
		engine->mmio_base = BSD_RING_BASE;
		engine->flush = bsd_ring_flush;
		if (IS_GEN5(dev_priv))
			engine->irq_enable_mask = ILK_BSD_USER_INTERRUPT;
		else
			engine->irq_enable_mask = I915_BSD_USER_INTERRUPT;
	}

	return intel_init_ring_buffer(engine);
}

/**
 * Initialize the second BSD ring (eg. Broadwell GT3, Skylake GT3)
 */
int intel_init_bsd2_ring_buffer(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;

	intel_ring_default_vfuncs(dev_priv, engine);

	engine->flush = gen6_bsd_ring_flush;

	return intel_init_ring_buffer(engine);
}

int intel_init_blt_ring_buffer(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;

	intel_ring_default_vfuncs(dev_priv, engine);

	engine->flush = gen6_ring_flush;
	if (INTEL_GEN(dev_priv) < 8)
		engine->irq_enable_mask = GT_BLT_USER_INTERRUPT;

	return intel_init_ring_buffer(engine);
}

int intel_init_vebox_ring_buffer(struct intel_engine_cs *engine)
{
	struct drm_i915_private *dev_priv = engine->i915;

	intel_ring_default_vfuncs(dev_priv, engine);

	engine->flush = gen6_ring_flush;

	if (INTEL_GEN(dev_priv) < 8) {
		engine->irq_enable_mask = PM_VEBOX_USER_INTERRUPT;
		engine->irq_enable = hsw_vebox_irq_enable;
		engine->irq_disable = hsw_vebox_irq_disable;
	}

	return intel_init_ring_buffer(engine);
}

int
intel_ring_flush_all_caches(struct drm_i915_gem_request *req)
{
	struct intel_engine_cs *engine = req->engine;
	int ret;

	if (!engine->gpu_caches_dirty)
		return 0;

	ret = engine->flush(req, 0, I915_GEM_GPU_DOMAINS);
	if (ret)
		return ret;

	trace_i915_gem_ring_flush(req, 0, I915_GEM_GPU_DOMAINS);

	engine->gpu_caches_dirty = false;
	return 0;
}

int
intel_ring_invalidate_all_caches(struct drm_i915_gem_request *req)
{
	struct intel_engine_cs *engine = req->engine;
	uint32_t flush_domains;
	int ret;

	flush_domains = 0;
	if (engine->gpu_caches_dirty)
		flush_domains = I915_GEM_GPU_DOMAINS;

	ret = engine->flush(req, I915_GEM_GPU_DOMAINS, flush_domains);
	if (ret)
		return ret;

	trace_i915_gem_ring_flush(req, I915_GEM_GPU_DOMAINS, flush_domains);

	engine->gpu_caches_dirty = false;
	return 0;
}

void
intel_stop_engine(struct intel_engine_cs *engine)
{
	int ret;

	if (!intel_engine_initialized(engine))
		return;

	ret = intel_engine_idle(engine);
	if (ret)
		DRM_ERROR("failed to quiesce %s whilst cleaning up: %d\n",
			  engine->name, ret);

	stop_ring(engine);
}