/*
 * Copyright © 2016 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/drm_print.h>

#include "gem/i915_gem_context.h"

#include "i915_drv.h"

#include "gt/intel_gt.h"

#include "intel_engine.h"
#include "intel_engine_pm.h"
#include "intel_engine_pool.h"
#include "intel_engine_user.h"
#include "intel_context.h"
#include "intel_lrc.h"
#include "intel_reset.h"

/* Haswell does have the CXT_SIZE register however it does not appear to be
 * valid. Now, docs explain in dwords what is in the context object. The full
 * size is 70720 bytes, however, the power context and execlist context will
 * never be saved (power context is stored elsewhere, and execlists don't work
 * on HSW) - so the final size, including the extra state required for the
 * Resource Streamer, is 66944 bytes, which rounds to 17 pages.
 */
#define HSW_CXT_TOTAL_SIZE              (17 * PAGE_SIZE)

#define DEFAULT_LR_CONTEXT_RENDER_SIZE  (22 * PAGE_SIZE)
#define GEN8_LR_CONTEXT_RENDER_SIZE     (20 * PAGE_SIZE)
#define GEN9_LR_CONTEXT_RENDER_SIZE     (22 * PAGE_SIZE)
#define GEN10_LR_CONTEXT_RENDER_SIZE    (18 * PAGE_SIZE)
#define GEN11_LR_CONTEXT_RENDER_SIZE    (14 * PAGE_SIZE)

#define GEN8_LR_CONTEXT_OTHER_SIZE      ( 2 * PAGE_SIZE)

#define MAX_MMIO_BASES 3
struct engine_info {
        unsigned int hw_id;
        u8 class;
        u8 instance;
        /* mmio bases table *must* be sorted in reverse gen order */
        struct engine_mmio_base {
                u32 gen : 8;
                u32 base : 24;
        } mmio_bases[MAX_MMIO_BASES];
};

static const struct engine_info intel_engines[] = {
        [RCS0] = {
                .hw_id = RCS0_HW,
                .class = RENDER_CLASS,
                .instance = 0,
                .mmio_bases = {
                        { .gen = 1, .base = RENDER_RING_BASE }
                },
        },
        [BCS0] = {
                .hw_id = BCS0_HW,
                .class = COPY_ENGINE_CLASS,
                .instance = 0,
                .mmio_bases = {
                        { .gen = 6, .base = BLT_RING_BASE }
                },
        },
        [VCS0] = {
                .hw_id = VCS0_HW,
                .class = VIDEO_DECODE_CLASS,
                .instance = 0,
                .mmio_bases = {
                        { .gen = 11, .base = GEN11_BSD_RING_BASE },
                        { .gen = 6, .base = GEN6_BSD_RING_BASE },
                        { .gen = 4, .base = BSD_RING_BASE }
                },
        },
        [VCS1] = {
                .hw_id = VCS1_HW,
                .class = VIDEO_DECODE_CLASS,
                .instance = 1,
                .mmio_bases = {
                        { .gen = 11, .base = GEN11_BSD2_RING_BASE },
                        { .gen = 8, .base = GEN8_BSD2_RING_BASE }
                },
        },
        [VCS2] = {
                .hw_id = VCS2_HW,
                .class = VIDEO_DECODE_CLASS,
                .instance = 2,
                .mmio_bases = {
                        { .gen = 11, .base = GEN11_BSD3_RING_BASE }
                },
        },
        [VCS3] = {
                .hw_id = VCS3_HW,
                .class = VIDEO_DECODE_CLASS,
                .instance = 3,
                .mmio_bases = {
                        { .gen = 11, .base = GEN11_BSD4_RING_BASE }
                },
        },
        [VECS0] = {
                .hw_id = VECS0_HW,
                .class = VIDEO_ENHANCEMENT_CLASS,
                .instance = 0,
                .mmio_bases = {
                        { .gen = 11, .base = GEN11_VEBOX_RING_BASE },
                        { .gen = 7, .base = VEBOX_RING_BASE }
                },
        },
        [VECS1] = {
                .hw_id = VECS1_HW,
                .class = VIDEO_ENHANCEMENT_CLASS,
                .instance = 1,
                .mmio_bases = {
                        { .gen = 11, .base = GEN11_VEBOX2_RING_BASE }
                },
        },
};

/**
 * intel_engine_context_size() - return the size of the context for an engine
 * @dev_priv: i915 device private
 * @class: engine class
 *
 * Each engine class may require a different amount of space for a context
 * image.
 *
 * Return: size (in bytes) of an engine class specific context image
 *
 * Note: this size includes the HWSP, which is part of the context image
 * in LRC mode, but does not include the "shared data page" used with
 * GuC submission. The caller should account for this if using the GuC.
 */
u32 intel_engine_context_size(struct drm_i915_private *dev_priv, u8 class)
{
        u32 cxt_size;

        BUILD_BUG_ON(I915_GTT_PAGE_SIZE != PAGE_SIZE);

        switch (class) {
        case RENDER_CLASS:
                switch (INTEL_GEN(dev_priv)) {
                default:
                        MISSING_CASE(INTEL_GEN(dev_priv));
                        return DEFAULT_LR_CONTEXT_RENDER_SIZE;
                case 12:
                case 11:
                        return GEN11_LR_CONTEXT_RENDER_SIZE;
                case 10:
                        return GEN10_LR_CONTEXT_RENDER_SIZE;
                case 9:
                        return GEN9_LR_CONTEXT_RENDER_SIZE;
                case 8:
                        return GEN8_LR_CONTEXT_RENDER_SIZE;
                case 7:
                        if (IS_HASWELL(dev_priv))
                                return HSW_CXT_TOTAL_SIZE;

                        cxt_size = I915_READ(GEN7_CXT_SIZE);
                        return round_up(GEN7_CXT_TOTAL_SIZE(cxt_size) * 64,
                                        PAGE_SIZE);
                case 6:
                        cxt_size = I915_READ(CXT_SIZE);
                        return round_up(GEN6_CXT_TOTAL_SIZE(cxt_size) * 64,
                                        PAGE_SIZE);
                case 5:
                case 4:
                        /*
                         * There is a discrepancy here between the size reported
                         * by the register and the size of the context layout
                         * in the docs. Both are described as authorative!
                         *
                         * The discrepancy is on the order of a few cachelines,
                         * but the total is under one page (4k), which is our
                         * minimum allocation anyway so it should all come
                         * out in the wash.
                         */
                        cxt_size = I915_READ(CXT_SIZE) + 1;
                        DRM_DEBUG_DRIVER("gen%d CXT_SIZE = %d bytes [0x%08x]\n",
                                         INTEL_GEN(dev_priv),
                                         cxt_size * 64,
                                         cxt_size - 1);
                        return round_up(cxt_size * 64, PAGE_SIZE);
                case 3:
                case 2:
                /* For the special day when i810 gets merged. */
                case 1:
                        return 0;
                }
                break;
        default:
                MISSING_CASE(class);
                /* fall through */
        case VIDEO_DECODE_CLASS:
        case VIDEO_ENHANCEMENT_CLASS:
        case COPY_ENGINE_CLASS:
                if (INTEL_GEN(dev_priv) < 8)
                        return 0;
                return GEN8_LR_CONTEXT_OTHER_SIZE;
        }
}

static u32 __engine_mmio_base(struct drm_i915_private *i915,
                              const struct engine_mmio_base *bases)
{
        int i;

        for (i = 0; i < MAX_MMIO_BASES; i++)
                if (INTEL_GEN(i915) >= bases[i].gen)
                        break;

        GEM_BUG_ON(i == MAX_MMIO_BASES);
        GEM_BUG_ON(!bases[i].base);

        return bases[i].base;
}

static void __sprint_engine_name(struct intel_engine_cs *engine)
{
        /*
         * Before we know what the uABI name for this engine will be,
         * we still would like to keep track of this engine in the debug logs.
         * We throw in a ' here as a reminder that this isn't its final name.
         */
        GEM_WARN_ON(snprintf(engine->name, sizeof(engine->name), "%s'%u",
                             intel_engine_class_repr(engine->class),
                             engine->instance) >= sizeof(engine->name));
}

void intel_engine_set_hwsp_writemask(struct intel_engine_cs *engine, u32 mask)
{
        /*
         * Though they added more rings on g4x/ilk, they did not add
         * per-engine HWSTAM until gen6.
         */
        if (INTEL_GEN(engine->i915) < 6 && engine->class != RENDER_CLASS)
                return;

        if (INTEL_GEN(engine->i915) >= 3)
                ENGINE_WRITE(engine, RING_HWSTAM, mask);
        else
                ENGINE_WRITE16(engine, RING_HWSTAM, mask);
}

static void intel_engine_sanitize_mmio(struct intel_engine_cs *engine)
{
        /* Mask off all writes into the unknown HWSP */
        intel_engine_set_hwsp_writemask(engine, ~0u);
}

static int intel_engine_setup(struct intel_gt *gt, enum intel_engine_id id)
{
        const struct engine_info *info = &intel_engines[id];
        struct intel_engine_cs *engine;

        BUILD_BUG_ON(MAX_ENGINE_CLASS >= BIT(GEN11_ENGINE_CLASS_WIDTH));
        BUILD_BUG_ON(MAX_ENGINE_INSTANCE >= BIT(GEN11_ENGINE_INSTANCE_WIDTH));

        if (GEM_DEBUG_WARN_ON(info->class > MAX_ENGINE_CLASS))
                return -EINVAL;

        if (GEM_DEBUG_WARN_ON(info->instance > MAX_ENGINE_INSTANCE))
                return -EINVAL;

        if (GEM_DEBUG_WARN_ON(gt->engine_class[info->class][info->instance]))
                return -EINVAL;

        engine = kzalloc(sizeof(*engine), GFP_KERNEL);
        if (!engine)
                return -ENOMEM;

        BUILD_BUG_ON(BITS_PER_TYPE(engine->mask) < I915_NUM_ENGINES);

        engine->id = id;
        engine->mask = BIT(id);
        engine->i915 = gt->i915;
        engine->gt = gt;
        engine->uncore = gt->uncore;
        engine->hw_id = engine->guc_id = info->hw_id;
        engine->mmio_base = __engine_mmio_base(gt->i915, info->mmio_bases);

        engine->class = info->class;
        engine->instance = info->instance;
        __sprint_engine_name(engine);

        /*
         * To be overridden by the backend on setup. However to facilitate
         * cleanup on error during setup, we always provide the destroy vfunc.
         */
        engine->destroy = (typeof(engine->destroy))kfree;

        engine->context_size = intel_engine_context_size(gt->i915,
                                                         engine->class);
        if (WARN_ON(engine->context_size > BIT(20)))
                engine->context_size = 0;
        if (engine->context_size)
                DRIVER_CAPS(gt->i915)->has_logical_contexts = true;

        /* Nothing to do here, execute in order of dependencies */
        engine->schedule = NULL;

        seqlock_init(&engine->stats.lock);

        ATOMIC_INIT_NOTIFIER_HEAD(&engine->context_status_notifier);

        /* Scrub mmio state on takeover */
        intel_engine_sanitize_mmio(engine);

        gt->engine_class[info->class][info->instance] = engine;

        intel_engine_add_user(engine);
        gt->i915->engine[id] = engine;

        return 0;
}

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

        if (engine->class == VIDEO_DECODE_CLASS) {
                /*
                 * HEVC support is present on first engine instance
                 * before Gen11 and on all instances afterwards.
                 */
                if (INTEL_GEN(i915) >= 11 ||
                    (INTEL_GEN(i915) >= 9 && engine->instance == 0))
                        engine->uabi_capabilities |=
                                I915_VIDEO_CLASS_CAPABILITY_HEVC;

                /*
                 * SFC block is present only on even logical engine
                 * instances.
                 */
                if ((INTEL_GEN(i915) >= 11 &&
                     RUNTIME_INFO(i915)->vdbox_sfc_access & engine->mask) ||
                    (INTEL_GEN(i915) >= 9 && engine->instance == 0))
                        engine->uabi_capabilities |=
                                I915_VIDEO_AND_ENHANCE_CLASS_CAPABILITY_SFC;
        } else if (engine->class == VIDEO_ENHANCEMENT_CLASS) {
                if (INTEL_GEN(i915) >= 9)
                        engine->uabi_capabilities |=
                                I915_VIDEO_AND_ENHANCE_CLASS_CAPABILITY_SFC;
        }
}

static void intel_setup_engine_capabilities(struct drm_i915_private *i915)
{
        struct intel_engine_cs *engine;
        enum intel_engine_id id;

        for_each_engine(engine, i915, id)
                __setup_engine_capabilities(engine);
}

/**
 * intel_engines_cleanup() - free the resources allocated for Command Streamers
 * @i915: the i915 devic
 */
void intel_engines_cleanup(struct drm_i915_private *i915)
{
        struct intel_engine_cs *engine;
        enum intel_engine_id id;

        for_each_engine(engine, i915, id) {
                engine->destroy(engine);
                i915->engine[id] = NULL;
        }
}

/**
 * intel_engines_init_mmio() - allocate and prepare the Engine Command Streamers
 * @i915: the i915 device
 *
 * Return: non-zero if the initialization failed.
 */
int intel_engines_init_mmio(struct drm_i915_private *i915)
{
        struct intel_device_info *device_info = mkwrite_device_info(i915);
        const unsigned int engine_mask = INTEL_INFO(i915)->engine_mask;
        unsigned int mask = 0;
        unsigned int i;
        int err;

        WARN_ON(engine_mask == 0);
        WARN_ON(engine_mask &
                GENMASK(BITS_PER_TYPE(mask) - 1, I915_NUM_ENGINES));

        if (i915_inject_probe_failure(i915))
                return -ENODEV;

        for (i = 0; i < ARRAY_SIZE(intel_engines); i++) {
                if (!HAS_ENGINE(i915, i))
                        continue;

                err = intel_engine_setup(&i915->gt, i);
                if (err)
                        goto cleanup;

                mask |= BIT(i);
        }

        /*
         * Catch failures to update intel_engines table when the new engines
         * are added to the driver by a warning and disabling the forgotten
         * engines.
         */
        if (WARN_ON(mask != engine_mask))
                device_info->engine_mask = mask;

        RUNTIME_INFO(i915)->num_engines = hweight32(mask);

        intel_gt_check_and_clear_faults(&i915->gt);

        intel_setup_engine_capabilities(i915);

        return 0;

cleanup:
        intel_engines_cleanup(i915);
        return err;
}

/**
 * intel_engines_init() - init the Engine Command Streamers
 * @i915: i915 device private
 *
 * Return: non-zero if the initialization failed.
 */
int intel_engines_init(struct drm_i915_private *i915)
{
        int (*init)(struct intel_engine_cs *engine);
        struct intel_engine_cs *engine;
        enum intel_engine_id id;
        int err;

        if (HAS_EXECLISTS(i915))
                init = intel_execlists_submission_init;
        else
                init = intel_ring_submission_init;

        for_each_engine(engine, i915, id) {
                err = init(engine);
                if (err)
                        goto cleanup;
        }

        return 0;

cleanup:
        intel_engines_cleanup(i915);
        return err;
}

void intel_engine_init_execlists(struct intel_engine_cs *engine)
{
        struct intel_engine_execlists * const execlists = &engine->execlists;

        execlists->port_mask = 1;
        GEM_BUG_ON(!is_power_of_2(execlists_num_ports(execlists)));
        GEM_BUG_ON(execlists_num_ports(execlists) > EXECLIST_MAX_PORTS);

        memset(execlists->pending, 0, sizeof(execlists->pending));
        execlists->active =
                memset(execlists->inflight, 0, sizeof(execlists->inflight));

        execlists->queue_priority_hint = INT_MIN;
        execlists->queue = RB_ROOT_CACHED;
}

static void cleanup_status_page(struct intel_engine_cs *engine)
{
        struct i915_vma *vma;

        /* Prevent writes into HWSP after returning the page to the system */
        intel_engine_set_hwsp_writemask(engine, ~0u);

        vma = fetch_and_zero(&engine->status_page.vma);
        if (!vma)
                return;

        if (!HWS_NEEDS_PHYSICAL(engine->i915))
                i915_vma_unpin(vma);

        i915_gem_object_unpin_map(vma->obj);
        i915_gem_object_put(vma->obj);
}

static int pin_ggtt_status_page(struct intel_engine_cs *engine,
                                struct i915_vma *vma)
{
        unsigned int flags;

        flags = PIN_GLOBAL;
        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
                 * actually map it).
                 */
                flags |= PIN_MAPPABLE;
        else
                flags |= PIN_HIGH;

        return i915_vma_pin(vma, 0, 0, flags);
}

static int init_status_page(struct intel_engine_cs *engine)
{
        struct drm_i915_gem_object *obj;
        struct i915_vma *vma;
        void *vaddr;
        int ret;

        /*
         * Though the HWS register does support 36bit addresses, historically
         * we have had hangs and corruption reported due to wild writes if
         * the HWS is placed above 4G. We only allow objects to be allocated
         * in GFP_DMA32 for i965, and no earlier physical address users had
         * access to more than 4G.
         */
        obj = i915_gem_object_create_internal(engine->i915, PAGE_SIZE);
        if (IS_ERR(obj)) {
                DRM_ERROR("Failed to allocate status page\n");
                return PTR_ERR(obj);
        }

        i915_gem_object_set_cache_coherency(obj, I915_CACHE_LLC);

        vma = i915_vma_instance(obj, &engine->gt->ggtt->vm, NULL);
        if (IS_ERR(vma)) {
                ret = PTR_ERR(vma);
                goto err;
        }

        vaddr = i915_gem_object_pin_map(obj, I915_MAP_WB);
        if (IS_ERR(vaddr)) {
                ret = PTR_ERR(vaddr);
                goto err;
        }

        engine->status_page.addr = memset(vaddr, 0, PAGE_SIZE);
        engine->status_page.vma = vma;

        if (!HWS_NEEDS_PHYSICAL(engine->i915)) {
                ret = pin_ggtt_status_page(engine, vma);
                if (ret)
                        goto err_unpin;
        }

        return 0;

err_unpin:
        i915_gem_object_unpin_map(obj);
err:
        i915_gem_object_put(obj);
        return ret;
}

static int intel_engine_setup_common(struct intel_engine_cs *engine)
{
        int err;

        init_llist_head(&engine->barrier_tasks);

        err = init_status_page(engine);
        if (err)
                return err;

        intel_engine_init_active(engine, ENGINE_PHYSICAL);
        intel_engine_init_breadcrumbs(engine);
        intel_engine_init_execlists(engine);
        intel_engine_init_hangcheck(engine);
        intel_engine_init_cmd_parser(engine);
        intel_engine_init__pm(engine);

        intel_engine_pool_init(&engine->pool);

        /* Use the whole device by default */
        engine->sseu =
                intel_sseu_from_device_info(&RUNTIME_INFO(engine->i915)->sseu);

        intel_engine_init_workarounds(engine);
        intel_engine_init_whitelist(engine);
        intel_engine_init_ctx_wa(engine);

        return 0;
}

/**
 * intel_engines_setup- setup engine state not requiring hw access
 * @i915: Device to setup.
 *
 * Initializes engine structure members shared between legacy and execlists
 * submission modes which do not require hardware access.
 *
 * Typically done early in the submission mode specific engine setup stage.
 */
int intel_engines_setup(struct drm_i915_private *i915)
{
        int (*setup)(struct intel_engine_cs *engine);
        struct intel_engine_cs *engine;
        enum intel_engine_id id;
        int err;

        if (HAS_EXECLISTS(i915))
                setup = intel_execlists_submission_setup;
        else
                setup = intel_ring_submission_setup;

        for_each_engine(engine, i915, id) {
                err = intel_engine_setup_common(engine);
                if (err)
                        goto cleanup;

                err = setup(engine);
                if (err)
                        goto cleanup;

                /* We expect the backend to take control over its state */
                GEM_BUG_ON(engine->destroy == (typeof(engine->destroy))kfree);

                GEM_BUG_ON(!engine->cops);
        }

        return 0;

cleanup:
        intel_engines_cleanup(i915);
        return err;
}

struct measure_breadcrumb {
        struct i915_request rq;
        struct intel_timeline timeline;
        struct intel_ring ring;
        u32 cs[1024];
};

static int measure_breadcrumb_dw(struct intel_engine_cs *engine)
{
        struct measure_breadcrumb *frame;
        int dw = -ENOMEM;

        GEM_BUG_ON(!engine->gt->scratch);

        frame = kzalloc(sizeof(*frame), GFP_KERNEL);
        if (!frame)
                return -ENOMEM;

        if (intel_timeline_init(&frame->timeline,
                                engine->gt,
                                engine->status_page.vma))
                goto out_frame;

        frame->ring.vaddr = frame->cs;
        frame->ring.size = sizeof(frame->cs);
        frame->ring.effective_size = frame->ring.size;
        intel_ring_update_space(&frame->ring);

        frame->rq.i915 = engine->i915;
        frame->rq.engine = engine;
        frame->rq.ring = &frame->ring;
        frame->rq.timeline = &frame->timeline;

        dw = intel_timeline_pin(&frame->timeline);
        if (dw < 0)
                goto out_timeline;

        dw = engine->emit_fini_breadcrumb(&frame->rq, frame->cs) - frame->cs;
        GEM_BUG_ON(dw & 1); /* RING_TAIL must be qword aligned */

        intel_timeline_unpin(&frame->timeline);

out_timeline:
        intel_timeline_fini(&frame->timeline);
out_frame:
        kfree(frame);
        return dw;
}

void
intel_engine_init_active(struct intel_engine_cs *engine, unsigned int subclass)
{
        INIT_LIST_HEAD(&engine->active.requests);

        spin_lock_init(&engine->active.lock);
        lockdep_set_subclass(&engine->active.lock, subclass);

        /*
         * Due to an interesting quirk in lockdep's internal debug tracking,
         * after setting a subclass we must ensure the lock is used. Otherwise,
         * nr_unused_locks is incremented once too often.
         */
#ifdef CONFIG_DEBUG_LOCK_ALLOC
        local_irq_disable();
        lock_map_acquire(&engine->active.lock.dep_map);
        lock_map_release(&engine->active.lock.dep_map);
        local_irq_enable();
#endif
}

static struct intel_context *
create_kernel_context(struct intel_engine_cs *engine)
{
        struct intel_context *ce;
        int err;

        ce = intel_context_create(engine->i915->kernel_context, engine);
        if (IS_ERR(ce))
                return ce;

        ce->ring = __intel_context_ring_size(SZ_4K);

        err = intel_context_pin(ce);
        if (err) {
                intel_context_put(ce);
                return ERR_PTR(err);
        }

        return ce;
}

/**
 * intel_engines_init_common - initialize cengine state which might require hw access
 * @engine: Engine to initialize.
 *
 * Initializes @engine@ structure members shared between legacy and execlists
 * submission modes which do require hardware access.
 *
 * Typcally done at later stages of submission mode specific engine setup.
 *
 * Returns zero on success or an error code on failure.
 */
int intel_engine_init_common(struct intel_engine_cs *engine)
{
        struct intel_context *ce;
        int ret;

        engine->set_default_submission(engine);

        /*
         * 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.
         */
        ce = create_kernel_context(engine);
        if (IS_ERR(ce))
                return PTR_ERR(ce);

        engine->kernel_context = ce;

        ret = measure_breadcrumb_dw(engine);
        if (ret < 0)
                goto err_unpin;

        engine->emit_fini_breadcrumb_dw = ret;

        return 0;

err_unpin:
        intel_context_unpin(ce);
        intel_context_put(ce);
        return ret;
}

/**
 * intel_engines_cleanup_common - cleans up the engine state created by
 *                                the common initiailizers.
 * @engine: Engine to cleanup.
 *
 * This cleans up everything created by the common helpers.
 */
void intel_engine_cleanup_common(struct intel_engine_cs *engine)
{
        GEM_BUG_ON(!list_empty(&engine->active.requests));

        cleanup_status_page(engine);

        intel_engine_pool_fini(&engine->pool);
        intel_engine_fini_breadcrumbs(engine);
        intel_engine_cleanup_cmd_parser(engine);

        if (engine->default_state)
                i915_gem_object_put(engine->default_state);

        intel_context_unpin(engine->kernel_context);
        intel_context_put(engine->kernel_context);
        GEM_BUG_ON(!llist_empty(&engine->barrier_tasks));

        intel_wa_list_free(&engine->ctx_wa_list);
        intel_wa_list_free(&engine->wa_list);
        intel_wa_list_free(&engine->whitelist);
}

u64 intel_engine_get_active_head(const struct intel_engine_cs *engine)
{
        struct drm_i915_private *i915 = engine->i915;

        u64 acthd;

        if (INTEL_GEN(i915) >= 8)
                acthd = ENGINE_READ64(engine, RING_ACTHD, RING_ACTHD_UDW);
        else if (INTEL_GEN(i915) >= 4)
                acthd = ENGINE_READ(engine, RING_ACTHD);
        else
                acthd = ENGINE_READ(engine, ACTHD);

        return acthd;
}

u64 intel_engine_get_last_batch_head(const struct intel_engine_cs *engine)
{
        u64 bbaddr;

        if (INTEL_GEN(engine->i915) >= 8)
                bbaddr = ENGINE_READ64(engine, RING_BBADDR, RING_BBADDR_UDW);
        else
                bbaddr = ENGINE_READ(engine, RING_BBADDR);

        return bbaddr;
}

int intel_engine_stop_cs(struct intel_engine_cs *engine)
{
        struct intel_uncore *uncore = engine->uncore;
        const u32 base = engine->mmio_base;
        const i915_reg_t mode = RING_MI_MODE(base);
        int err;

        if (INTEL_GEN(engine->i915) < 3)
                return -ENODEV;

        GEM_TRACE("%s\n", engine->name);

        intel_uncore_write_fw(uncore, mode, _MASKED_BIT_ENABLE(STOP_RING));

        err = 0;
        if (__intel_wait_for_register_fw(uncore,
                                         mode, MODE_IDLE, MODE_IDLE,
                                         1000, 0,
                                         NULL)) {
                GEM_TRACE("%s: timed out on STOP_RING -> IDLE\n", engine->name);
                err = -ETIMEDOUT;
        }

        /* A final mmio read to let GPU writes be hopefully flushed to memory */
        intel_uncore_posting_read_fw(uncore, mode);

        return err;
}

void intel_engine_cancel_stop_cs(struct intel_engine_cs *engine)
{
        GEM_TRACE("%s\n", engine->name);

        ENGINE_WRITE_FW(engine, RING_MI_MODE, _MASKED_BIT_DISABLE(STOP_RING));
}

const char *i915_cache_level_str(struct drm_i915_private *i915, int type)
{
        switch (type) {
        case I915_CACHE_NONE: return " uncached";
        case I915_CACHE_LLC: return HAS_LLC(i915) ? " LLC" : " snooped";
        case I915_CACHE_L3_LLC: return " L3+LLC";
        case I915_CACHE_WT: return " WT";
        default: return "";
        }
}

static u32
read_subslice_reg(struct intel_engine_cs *engine, int slice, int subslice,
                  i915_reg_t reg)
{
        struct drm_i915_private *i915 = engine->i915;
        struct intel_uncore *uncore = engine->uncore;
        u32 mcr_mask, mcr_ss, mcr, old_mcr, val;
        enum forcewake_domains fw_domains;

        if (INTEL_GEN(i915) >= 11) {
                mcr_mask = GEN11_MCR_SLICE_MASK | GEN11_MCR_SUBSLICE_MASK;
                mcr_ss = GEN11_MCR_SLICE(slice) | GEN11_MCR_SUBSLICE(subslice);
        } else {
                mcr_mask = GEN8_MCR_SLICE_MASK | GEN8_MCR_SUBSLICE_MASK;
                mcr_ss = GEN8_MCR_SLICE(slice) | GEN8_MCR_SUBSLICE(subslice);
        }

        fw_domains = intel_uncore_forcewake_for_reg(uncore, reg,
                                                    FW_REG_READ);
        fw_domains |= intel_uncore_forcewake_for_reg(uncore,
                                                     GEN8_MCR_SELECTOR,
                                                     FW_REG_READ | FW_REG_WRITE);

        spin_lock_irq(&uncore->lock);
        intel_uncore_forcewake_get__locked(uncore, fw_domains);

        old_mcr = mcr = intel_uncore_read_fw(uncore, GEN8_MCR_SELECTOR);

        mcr &= ~mcr_mask;
        mcr |= mcr_ss;
        intel_uncore_write_fw(uncore, GEN8_MCR_SELECTOR, mcr);

        val = intel_uncore_read_fw(uncore, reg);

        mcr &= ~mcr_mask;
        mcr |= old_mcr & mcr_mask;

        intel_uncore_write_fw(uncore, GEN8_MCR_SELECTOR, mcr);

        intel_uncore_forcewake_put__locked(uncore, fw_domains);
        spin_unlock_irq(&uncore->lock);

        return val;
}

/* NB: please notice the memset */
void intel_engine_get_instdone(struct intel_engine_cs *engine,
                               struct intel_instdone *instdone)
{
        struct drm_i915_private *i915 = engine->i915;
        struct intel_uncore *uncore = engine->uncore;
        u32 mmio_base = engine->mmio_base;
        int slice;
        int subslice;

        memset(instdone, 0, sizeof(*instdone));

        switch (INTEL_GEN(i915)) {
        default:
                instdone->instdone =
                        intel_uncore_read(uncore, RING_INSTDONE(mmio_base));

                if (engine->id != RCS0)
                        break;

                instdone->slice_common =
                        intel_uncore_read(uncore, GEN7_SC_INSTDONE);
                for_each_instdone_slice_subslice(i915, slice, subslice) {
                        instdone->sampler[slice][subslice] =
                                read_subslice_reg(engine, slice, subslice,
                                                  GEN7_SAMPLER_INSTDONE);
                        instdone->row[slice][subslice] =
                                read_subslice_reg(engine, slice, subslice,
                                                  GEN7_ROW_INSTDONE);
                }
                break;
        case 7:
                instdone->instdone =
                        intel_uncore_read(uncore, RING_INSTDONE(mmio_base));

                if (engine->id != RCS0)
                        break;

                instdone->slice_common =
                        intel_uncore_read(uncore, GEN7_SC_INSTDONE);
                instdone->sampler[0][0] =
                        intel_uncore_read(uncore, GEN7_SAMPLER_INSTDONE);
                instdone->row[0][0] =
                        intel_uncore_read(uncore, GEN7_ROW_INSTDONE);

                break;
        case 6:
        case 5:
        case 4:
                instdone->instdone =
                        intel_uncore_read(uncore, RING_INSTDONE(mmio_base));
                if (engine->id == RCS0)
                        /* HACK: Using the wrong struct member */
                        instdone->slice_common =
                                intel_uncore_read(uncore, GEN4_INSTDONE1);

                break;
        case 3:
        case 2:
                instdone->instdone = intel_uncore_read(uncore, GEN2_INSTDONE);
                break;
        }
}

static bool ring_is_idle(struct intel_engine_cs *engine)
{
        bool idle = true;

        if (I915_SELFTEST_ONLY(!engine->mmio_base))
                return true;

        if (!intel_engine_pm_get_if_awake(engine))
                return true;

        /* First check that no commands are left in the ring */
        if ((ENGINE_READ(engine, RING_HEAD) & HEAD_ADDR) !=
            (ENGINE_READ(engine, RING_TAIL) & TAIL_ADDR))
                idle = false;

        /* No bit for gen2, so assume the CS parser is idle */
        if (INTEL_GEN(engine->i915) > 2 &&
            !(ENGINE_READ(engine, RING_MI_MODE) & MODE_IDLE))
                idle = false;

        intel_engine_pm_put(engine);

        return idle;
}

/**
 * intel_engine_is_idle() - Report if the engine has finished process all work
 * @engine: the intel_engine_cs
 *
 * Return true if there are no requests pending, nothing left to be submitted
 * to hardware, and that the engine is idle.
 */
bool intel_engine_is_idle(struct intel_engine_cs *engine)
{
        /* More white lies, if wedged, hw state is inconsistent */
        if (intel_gt_is_wedged(engine->gt))
                return true;

        if (!intel_engine_pm_is_awake(engine))
                return true;

        /* Waiting to drain ELSP? */
        if (execlists_active(&engine->execlists)) {
                struct tasklet_struct *t = &engine->execlists.tasklet;

                synchronize_hardirq(engine->i915->drm.pdev->irq);

                local_bh_disable();
                if (tasklet_trylock(t)) {
                        /* Must wait for any GPU reset in progress. */
                        if (__tasklet_is_enabled(t))
                                t->func(t->data);
                        tasklet_unlock(t);
                }
                local_bh_enable();

                /* Otherwise flush the tasklet if it was on another cpu */
                tasklet_unlock_wait(t);

                if (execlists_active(&engine->execlists))
                        return false;
        }

        /* ELSP is empty, but there are ready requests? E.g. after reset */
        if (!RB_EMPTY_ROOT(&engine->execlists.queue.rb_root))
                return false;

        /* Ring stopped? */
        return ring_is_idle(engine);
}

bool intel_engines_are_idle(struct intel_gt *gt)
{
        struct intel_engine_cs *engine;
        enum intel_engine_id id;

        /*
         * If the driver is wedged, HW state may be very inconsistent and
         * report that it is still busy, even though we have stopped using it.
         */
        if (intel_gt_is_wedged(gt))
                return true;

        /* Already parked (and passed an idleness test); must still be idle */
        if (!READ_ONCE(gt->awake))
                return true;

        for_each_engine(engine, gt->i915, id) {
                if (!intel_engine_is_idle(engine))
                        return false;
        }

        return true;
}

void intel_engines_reset_default_submission(struct intel_gt *gt)
{
        struct intel_engine_cs *engine;
        enum intel_engine_id id;

        for_each_engine(engine, gt->i915, id)
                engine->set_default_submission(engine);
}

bool intel_engine_can_store_dword(struct intel_engine_cs *engine)
{
        switch (INTEL_GEN(engine->i915)) {
        case 2:
                return false; /* uses physical not virtual addresses */
        case 3:
                /* maybe only uses physical not virtual addresses */
                return !(IS_I915G(engine->i915) || IS_I915GM(engine->i915));
        case 6:
                return engine->class != VIDEO_DECODE_CLASS; /* b0rked */
        default:
                return true;
        }
}

static int print_sched_attr(struct drm_i915_private *i915,
                            const struct i915_sched_attr *attr,
                            char *buf, int x, int len)
{
        if (attr->priority == I915_PRIORITY_INVALID)
                return x;

        x += snprintf(buf + x, len - x,
                      " prio=%d", attr->priority);

        return x;
}

static void print_request(struct drm_printer *m,
                          struct i915_request *rq,
                          const char *prefix)
{
        const char *name = rq->fence.ops->get_timeline_name(&rq->fence);
        char buf[80] = "";
        int x = 0;

        x = print_sched_attr(rq->i915, &rq->sched.attr, buf, x, sizeof(buf));

        drm_printf(m, "%s %llx:%llx%s%s %s @ %dms: %s\n",
                   prefix,
                   rq->fence.context, rq->fence.seqno,
                   i915_request_completed(rq) ? "!" :
                   i915_request_started(rq) ? "*" :
                   "",
                   test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
                            &rq->fence.flags) ? "+" :
                   test_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
                            &rq->fence.flags) ? "-" :
                   "",
                   buf,
                   jiffies_to_msecs(jiffies - rq->emitted_jiffies),
                   name);
}

static void hexdump(struct drm_printer *m, const void *buf, size_t len)
{
        const size_t rowsize = 8 * sizeof(u32);
        const void *prev = NULL;
        bool skip = false;
        size_t pos;

        for (pos = 0; pos < len; pos += rowsize) {
                char line[128];

                if (prev && !memcmp(prev, buf + pos, rowsize)) {
                        if (!skip) {
                                drm_printf(m, "*\n");
                                skip = true;
                        }
                        continue;
                }

                WARN_ON_ONCE(hex_dump_to_buffer(buf + pos, len - pos,
                                                rowsize, sizeof(u32),
                                                line, sizeof(line),
                                                false) >= sizeof(line));
                drm_printf(m, "[%04zx] %s\n", pos, line);

                prev = buf + pos;
                skip = false;
        }
}

static void intel_engine_print_registers(struct intel_engine_cs *engine,
                                         struct drm_printer *m)
{
        struct drm_i915_private *dev_priv = engine->i915;
        struct intel_engine_execlists * const execlists = &engine->execlists;
        u64 addr;

        if (engine->id == RENDER_CLASS && IS_GEN_RANGE(dev_priv, 4, 7))
                drm_printf(m, "\tCCID: 0x%08x\n", ENGINE_READ(engine, CCID));
        drm_printf(m, "\tRING_START: 0x%08x\n",
                   ENGINE_READ(engine, RING_START));
        drm_printf(m, "\tRING_HEAD:  0x%08x\n",
                   ENGINE_READ(engine, RING_HEAD) & HEAD_ADDR);
        drm_printf(m, "\tRING_TAIL:  0x%08x\n",
                   ENGINE_READ(engine, RING_TAIL) & TAIL_ADDR);
        drm_printf(m, "\tRING_CTL:   0x%08x%s\n",
                   ENGINE_READ(engine, RING_CTL),
                   ENGINE_READ(engine, RING_CTL) & (RING_WAIT | RING_WAIT_SEMAPHORE) ? " [waiting]" : "");
        if (INTEL_GEN(engine->i915) > 2) {
                drm_printf(m, "\tRING_MODE:  0x%08x%s\n",
                           ENGINE_READ(engine, RING_MI_MODE),
                           ENGINE_READ(engine, RING_MI_MODE) & (MODE_IDLE) ? " [idle]" : "");
        }

        if (INTEL_GEN(dev_priv) >= 6) {
                drm_printf(m, "\tRING_IMR: %08x\n",
                           ENGINE_READ(engine, RING_IMR));
        }

        addr = intel_engine_get_active_head(engine);
        drm_printf(m, "\tACTHD:  0x%08x_%08x\n",
                   upper_32_bits(addr), lower_32_bits(addr));
        addr = intel_engine_get_last_batch_head(engine);
        drm_printf(m, "\tBBADDR: 0x%08x_%08x\n",
                   upper_32_bits(addr), lower_32_bits(addr));
        if (INTEL_GEN(dev_priv) >= 8)
                addr = ENGINE_READ64(engine, RING_DMA_FADD, RING_DMA_FADD_UDW);
        else if (INTEL_GEN(dev_priv) >= 4)
                addr = ENGINE_READ(engine, RING_DMA_FADD);
        else
                addr = ENGINE_READ(engine, DMA_FADD_I8XX);
        drm_printf(m, "\tDMA_FADDR: 0x%08x_%08x\n",
                   upper_32_bits(addr), lower_32_bits(addr));
        if (INTEL_GEN(dev_priv) >= 4) {
                drm_printf(m, "\tIPEIR: 0x%08x\n",
                           ENGINE_READ(engine, RING_IPEIR));
                drm_printf(m, "\tIPEHR: 0x%08x\n",
                           ENGINE_READ(engine, RING_IPEHR));
        } else {
                drm_printf(m, "\tIPEIR: 0x%08x\n", ENGINE_READ(engine, IPEIR));
                drm_printf(m, "\tIPEHR: 0x%08x\n", ENGINE_READ(engine, IPEHR));
        }

        if (HAS_EXECLISTS(dev_priv)) {
                struct i915_request * const *port, *rq;
                const u32 *hws =
                        &engine->status_page.addr[I915_HWS_CSB_BUF0_INDEX];
                const u8 num_entries = execlists->csb_size;
                unsigned int idx;
                u8 read, write;

                drm_printf(m, "\tExeclist status: 0x%08x %08x, entries %u\n",
                           ENGINE_READ(engine, RING_EXECLIST_STATUS_LO),
                           ENGINE_READ(engine, RING_EXECLIST_STATUS_HI),
                           num_entries);

                read = execlists->csb_head;
                write = READ_ONCE(*execlists->csb_write);

                drm_printf(m, "\tExeclist CSB read %d, write %d, tasklet queued? %s (%s)\n",
                           read, write,
                           yesno(test_bit(TASKLET_STATE_SCHED,
                                          &engine->execlists.tasklet.state)),
                           enableddisabled(!atomic_read(&engine->execlists.tasklet.count)));
                if (read >= num_entries)
                        read = 0;
                if (write >= num_entries)
                        write = 0;
                if (read > write)
                        write += num_entries;
                while (read < write) {
                        idx = ++read % num_entries;
                        drm_printf(m, "\tExeclist CSB[%d]: 0x%08x, context: %d\n",
                                   idx, hws[idx * 2], hws[idx * 2 + 1]);
                }

                execlists_active_lock_bh(execlists);
                for (port = execlists->active; (rq = *port); port++) {
                        char hdr[80];
                        int len;

                        len = snprintf(hdr, sizeof(hdr),
                                       "\t\tActive[%d: ",
                                       (int)(port - execlists->active));
                        if (!i915_request_signaled(rq))
                                len += snprintf(hdr + len, sizeof(hdr) - len,
                                                "ring:{start:%08x, hwsp:%08x, seqno:%08x}, ",
                                                i915_ggtt_offset(rq->ring->vma),
                                                rq->timeline->hwsp_offset,
                                                hwsp_seqno(rq));
                        snprintf(hdr + len, sizeof(hdr) - len, "rq: ");
                        print_request(m, rq, hdr);
                }
                for (port = execlists->pending; (rq = *port); port++) {
                        char hdr[80];

                        snprintf(hdr, sizeof(hdr),
                                 "\t\tPending[%d] ring:{start:%08x, hwsp:%08x, seqno:%08x}, rq: ",
                                 (int)(port - execlists->pending),
                                 i915_ggtt_offset(rq->ring->vma),
                                 rq->timeline->hwsp_offset,
                                 hwsp_seqno(rq));
                        print_request(m, rq, hdr);
                }
                execlists_active_unlock_bh(execlists);
        } else if (INTEL_GEN(dev_priv) > 6) {
                drm_printf(m, "\tPP_DIR_BASE: 0x%08x\n",
                           ENGINE_READ(engine, RING_PP_DIR_BASE));
                drm_printf(m, "\tPP_DIR_BASE_READ: 0x%08x\n",
                           ENGINE_READ(engine, RING_PP_DIR_BASE_READ));
                drm_printf(m, "\tPP_DIR_DCLV: 0x%08x\n",
                           ENGINE_READ(engine, RING_PP_DIR_DCLV));
        }
}

static void print_request_ring(struct drm_printer *m, struct i915_request *rq)
{
        void *ring;
        int size;

        drm_printf(m,
                   "[head %04x, postfix %04x, tail %04x, batch 0x%08x_%08x]:\n",
                   rq->head, rq->postfix, rq->tail,
                   rq->batch ? upper_32_bits(rq->batch->node.start) : ~0u,
                   rq->batch ? lower_32_bits(rq->batch->node.start) : ~0u);

        size = rq->tail - rq->head;
        if (rq->tail < rq->head)
                size += rq->ring->size;

        ring = kmalloc(size, GFP_ATOMIC);
        if (ring) {
                const void *vaddr = rq->ring->vaddr;
                unsigned int head = rq->head;
                unsigned int len = 0;

                if (rq->tail < head) {
                        len = rq->ring->size - head;
                        memcpy(ring, vaddr + head, len);
                        head = 0;
                }
                memcpy(ring + len, vaddr + head, size - len);

                hexdump(m, ring, size);
                kfree(ring);
        }
}

void intel_engine_dump(struct intel_engine_cs *engine,
                       struct drm_printer *m,
                       const char *header, ...)
{
        struct i915_gpu_error * const error = &engine->i915->gpu_error;
        struct i915_request *rq;
        intel_wakeref_t wakeref;
        unsigned long flags;

        if (header) {
                va_list ap;

                va_start(ap, header);
                drm_vprintf(m, header, &ap);
                va_end(ap);
        }

        if (intel_gt_is_wedged(engine->gt))
                drm_printf(m, "*** WEDGED ***\n");

        drm_printf(m, "\tAwake? %d\n", atomic_read(&engine->wakeref.count));
        drm_printf(m, "\tHangcheck: %d ms ago\n",
                   jiffies_to_msecs(jiffies - engine->hangcheck.action_timestamp));
        drm_printf(m, "\tReset count: %d (global %d)\n",
                   i915_reset_engine_count(error, engine),
                   i915_reset_count(error));

        drm_printf(m, "\tRequests:\n");

        spin_lock_irqsave(&engine->active.lock, flags);
        rq = intel_engine_find_active_request(engine);
        if (rq) {
                print_request(m, rq, "\t\tactive ");

                drm_printf(m, "\t\tring->start:  0x%08x\n",
                           i915_ggtt_offset(rq->ring->vma));
                drm_printf(m, "\t\tring->head:   0x%08x\n",
                           rq->ring->head);
                drm_printf(m, "\t\tring->tail:   0x%08x\n",
                           rq->ring->tail);
                drm_printf(m, "\t\tring->emit:   0x%08x\n",
                           rq->ring->emit);
                drm_printf(m, "\t\tring->space:  0x%08x\n",
                           rq->ring->space);
                drm_printf(m, "\t\tring->hwsp:   0x%08x\n",
                           rq->timeline->hwsp_offset);

                print_request_ring(m, rq);
        }
        spin_unlock_irqrestore(&engine->active.lock, flags);

        drm_printf(m, "\tMMIO base:  0x%08x\n", engine->mmio_base);
        wakeref = intel_runtime_pm_get_if_in_use(&engine->i915->runtime_pm);
        if (wakeref) {
                intel_engine_print_registers(engine, m);
                intel_runtime_pm_put(&engine->i915->runtime_pm, wakeref);
        } else {
                drm_printf(m, "\tDevice is asleep; skipping register dump\n");
        }

        intel_execlists_show_requests(engine, m, print_request, 8);

        drm_printf(m, "HWSP:\n");
        hexdump(m, engine->status_page.addr, PAGE_SIZE);

        drm_printf(m, "Idle? %s\n", yesno(intel_engine_is_idle(engine)));

        intel_engine_print_breadcrumbs(engine, m);
}

/**
 * intel_enable_engine_stats() - Enable engine busy tracking on engine
 * @engine: engine to enable stats collection
 *
 * Start collecting the engine busyness data for @engine.
 *
 * Returns 0 on success or a negative error code.
 */
int intel_enable_engine_stats(struct intel_engine_cs *engine)
{
        struct intel_engine_execlists *execlists = &engine->execlists;
        unsigned long flags;
        int err = 0;

        if (!intel_engine_supports_stats(engine))
                return -ENODEV;

        execlists_active_lock_bh(execlists);
        write_seqlock_irqsave(&engine->stats.lock, flags);

        if (unlikely(engine->stats.enabled == ~0)) {
                err = -EBUSY;
                goto unlock;
        }

        if (engine->stats.enabled++ == 0) {
                struct i915_request * const *port;
                struct i915_request *rq;

                engine->stats.enabled_at = ktime_get();

                /* XXX submission method oblivious? */
                for (port = execlists->active; (rq = *port); port++)
                        engine->stats.active++;

                for (port = execlists->pending; (rq = *port); port++) {
                        /* Exclude any contexts already counted in active */
                        if (!intel_context_inflight_count(rq->hw_context))
                                engine->stats.active++;
                }

                if (engine->stats.active)
                        engine->stats.start = engine->stats.enabled_at;
        }

unlock:
        write_sequnlock_irqrestore(&engine->stats.lock, flags);
        execlists_active_unlock_bh(execlists);

        return err;
}

static ktime_t __intel_engine_get_busy_time(struct intel_engine_cs *engine)
{
        ktime_t total = engine->stats.total;

        /*
         * If the engine is executing something at the moment
         * add it to the total.
         */
        if (engine->stats.active)
                total = ktime_add(total,
                                  ktime_sub(ktime_get(), engine->stats.start));

        return total;
}

/**
 * intel_engine_get_busy_time() - Return current accumulated engine busyness
 * @engine: engine to report on
 *
 * Returns accumulated time @engine was busy since engine stats were enabled.
 */
ktime_t intel_engine_get_busy_time(struct intel_engine_cs *engine)
{
        unsigned int seq;
        ktime_t total;

        do {
                seq = read_seqbegin(&engine->stats.lock);
                total = __intel_engine_get_busy_time(engine);
        } while (read_seqretry(&engine->stats.lock, seq));

        return total;
}

/**
 * intel_disable_engine_stats() - Disable engine busy tracking on engine
 * @engine: engine to disable stats collection
 *
 * Stops collecting the engine busyness data for @engine.
 */
void intel_disable_engine_stats(struct intel_engine_cs *engine)
{
        unsigned long flags;

        if (!intel_engine_supports_stats(engine))
                return;

        write_seqlock_irqsave(&engine->stats.lock, flags);
        WARN_ON_ONCE(engine->stats.enabled == 0);
        if (--engine->stats.enabled == 0) {
                engine->stats.total = __intel_engine_get_busy_time(engine);
                engine->stats.active = 0;
        }
        write_sequnlock_irqrestore(&engine->stats.lock, flags);
}

static bool match_ring(struct i915_request *rq)
{
        u32 ring = ENGINE_READ(rq->engine, RING_START);

        return ring == i915_ggtt_offset(rq->ring->vma);
}

struct i915_request *
intel_engine_find_active_request(struct intel_engine_cs *engine)
{
        struct i915_request *request, *active = NULL;

        /*
         * We are called by the error capture, reset and to dump engine
         * state at random points in time. In particular, note that neither is
         * crucially ordered with an interrupt. After a hang, the GPU is dead
         * and we assume that no more writes can happen (we waited long enough
         * for all writes that were in transaction to be flushed) - adding an
         * extra delay for a recent interrupt is pointless. Hence, we do
         * not need an engine->irq_seqno_barrier() before the seqno reads.
         * At all other times, we must assume the GPU is still running, but
         * we only care about the snapshot of this moment.
         */
        lockdep_assert_held(&engine->active.lock);
        list_for_each_entry(request, &engine->active.requests, sched.link) {
                if (i915_request_completed(request))
                        continue;

                if (!i915_request_started(request))
                        continue;

                /* More than one preemptible request may match! */
                if (!match_ring(request))
                        continue;

                active = request;
                break;
        }

        return active;
}

#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
#include "mock_engine.c"
#include "selftest_engine.c"
#include "selftest_engine_cs.c"
#endif