// SPDX-License-Identifier: MIT
/*
 * Copyright © 2014 Intel Corporation
 */

#include <linux/circ_buf.h>

#include "gem/i915_gem_context.h"
#include "gt/intel_context.h"
#include "gt/intel_engine_pm.h"
#include "gt/intel_gt.h"
#include "gt/intel_gt_pm.h"
#include "gt/intel_lrc_reg.h"
#include "gt/intel_ring.h"

#include "intel_guc_submission.h"

#include "i915_drv.h"
#include "i915_trace.h"

/**
 * DOC: GuC-based command submission
 *
 * IMPORTANT NOTE: GuC submission is currently not supported in i915. The GuC
 * firmware is moving to an updated submission interface and we plan to
 * turn submission back on when that lands. The below documentation (and related
 * code) matches the old submission model and will be updated as part of the
 * upgrade to the new flow.
 *
 * GuC stage descriptor:
 * During initialization, the driver allocates a static pool of 1024 such
 * descriptors, and shares them with the GuC. Currently, we only use one
 * descriptor. This stage descriptor lets the GuC know about the workqueue and
 * process descriptor. Theoretically, it also lets the GuC know about our HW
 * contexts (context ID, etc...), but we actually employ a kind of submission
 * where the GuC uses the LRCA sent via the work item instead. This is called
 * a "proxy" submission.
 *
 * The Scratch registers:
 * There are 16 MMIO-based registers start from 0xC180. The kernel driver writes
 * a value to the action register (SOFT_SCRATCH_0) along with any data. It then
 * triggers an interrupt on the GuC via another register write (0xC4C8).
 * Firmware writes a success/fail code back to the action register after
 * processes the request. The kernel driver polls waiting for this update and
 * then proceeds.
 *
 * Work Items:
 * There are several types of work items that the host may place into a
 * workqueue, each with its own requirements and limitations. Currently only
 * WQ_TYPE_INORDER is needed to support legacy submission via GuC, which
 * represents in-order queue. The kernel driver packs ring tail pointer and an
 * ELSP context descriptor dword into Work Item.
 * See guc_add_request()
 *
 */

static inline struct i915_priolist *to_priolist(struct rb_node *rb)
{
        return rb_entry(rb, struct i915_priolist, node);
}

static struct guc_stage_desc *__get_stage_desc(struct intel_guc *guc, u32 id)
{
        struct guc_stage_desc *base = guc->stage_desc_pool_vaddr;

        return &base[id];
}

static int guc_workqueue_create(struct intel_guc *guc)
{
        return intel_guc_allocate_and_map_vma(guc, GUC_WQ_SIZE, &guc->workqueue,
                                              &guc->workqueue_vaddr);
}

static void guc_workqueue_destroy(struct intel_guc *guc)
{
        i915_vma_unpin_and_release(&guc->workqueue, I915_VMA_RELEASE_MAP);
}

/*
 * Initialise the process descriptor shared with the GuC firmware.
 */
static int guc_proc_desc_create(struct intel_guc *guc)
{
        const u32 size = PAGE_ALIGN(sizeof(struct guc_process_desc));

        return intel_guc_allocate_and_map_vma(guc, size, &guc->proc_desc,
                                              &guc->proc_desc_vaddr);
}

static void guc_proc_desc_destroy(struct intel_guc *guc)
{
        i915_vma_unpin_and_release(&guc->proc_desc, I915_VMA_RELEASE_MAP);
}

static void guc_proc_desc_init(struct intel_guc *guc)
{
        struct guc_process_desc *desc;

        desc = memset(guc->proc_desc_vaddr, 0, sizeof(*desc));

        /*
         * XXX: pDoorbell and WQVBaseAddress are pointers in process address
         * space for ring3 clients (set them as in mmap_ioctl) or kernel
         * space for kernel clients (map on demand instead? May make debug
         * easier to have it mapped).
         */
        desc->wq_base_addr = 0;
        desc->db_base_addr = 0;

        desc->wq_size_bytes = GUC_WQ_SIZE;
        desc->wq_status = WQ_STATUS_ACTIVE;
        desc->priority = GUC_CLIENT_PRIORITY_KMD_NORMAL;
}

static void guc_proc_desc_fini(struct intel_guc *guc)
{
        memset(guc->proc_desc_vaddr, 0, sizeof(struct guc_process_desc));
}

static int guc_stage_desc_pool_create(struct intel_guc *guc)
{
        u32 size = PAGE_ALIGN(sizeof(struct guc_stage_desc) *
                              GUC_MAX_STAGE_DESCRIPTORS);

        return intel_guc_allocate_and_map_vma(guc, size, &guc->stage_desc_pool,
                                              &guc->stage_desc_pool_vaddr);
}

static void guc_stage_desc_pool_destroy(struct intel_guc *guc)
{
        i915_vma_unpin_and_release(&guc->stage_desc_pool, I915_VMA_RELEASE_MAP);
}

/*
 * Initialise/clear the stage descriptor shared with the GuC firmware.
 *
 * This descriptor tells the GuC where (in GGTT space) to find the important
 * data structures related to work submission (process descriptor, write queue,
 * etc).
 */
static void guc_stage_desc_init(struct intel_guc *guc)
{
        struct guc_stage_desc *desc;

        /* we only use 1 stage desc, so hardcode it to 0 */
        desc = __get_stage_desc(guc, 0);
        memset(desc, 0, sizeof(*desc));

        desc->attribute = GUC_STAGE_DESC_ATTR_ACTIVE |
                          GUC_STAGE_DESC_ATTR_KERNEL;

        desc->stage_id = 0;
        desc->priority = GUC_CLIENT_PRIORITY_KMD_NORMAL;

        desc->process_desc = intel_guc_ggtt_offset(guc, guc->proc_desc);
        desc->wq_addr = intel_guc_ggtt_offset(guc, guc->workqueue);
        desc->wq_size = GUC_WQ_SIZE;
}

static void guc_stage_desc_fini(struct intel_guc *guc)
{
        struct guc_stage_desc *desc;

        desc = __get_stage_desc(guc, 0);
        memset(desc, 0, sizeof(*desc));
}

/* Construct a Work Item and append it to the GuC's Work Queue */
static void guc_wq_item_append(struct intel_guc *guc,
                               u32 target_engine, u32 context_desc,
                               u32 ring_tail, u32 fence_id)
{
        /* wqi_len is in DWords, and does not include the one-word header */
        const size_t wqi_size = sizeof(struct guc_wq_item);
        const u32 wqi_len = wqi_size / sizeof(u32) - 1;
        struct guc_process_desc *desc = guc->proc_desc_vaddr;
        struct guc_wq_item *wqi;
        u32 wq_off;

        lockdep_assert_held(&guc->wq_lock);

        /* For now workqueue item is 4 DWs; workqueue buffer is 2 pages. So we
         * should not have the case where structure wqi is across page, neither
         * wrapped to the beginning. This simplifies the implementation below.
         *
         * XXX: if not the case, we need save data to a temp wqi and copy it to
         * workqueue buffer dw by dw.
         */
        BUILD_BUG_ON(wqi_size != 16);

        /* We expect the WQ to be active if we're appending items to it */
        GEM_BUG_ON(desc->wq_status != WQ_STATUS_ACTIVE);

        /* Free space is guaranteed. */
        wq_off = READ_ONCE(desc->tail);
        GEM_BUG_ON(CIRC_SPACE(wq_off, READ_ONCE(desc->head),
                              GUC_WQ_SIZE) < wqi_size);
        GEM_BUG_ON(wq_off & (wqi_size - 1));

        wqi = guc->workqueue_vaddr + wq_off;

        /* Now fill in the 4-word work queue item */
        wqi->header = WQ_TYPE_INORDER |
                      (wqi_len << WQ_LEN_SHIFT) |
                      (target_engine << WQ_TARGET_SHIFT) |
                      WQ_NO_WCFLUSH_WAIT;
        wqi->context_desc = context_desc;
        wqi->submit_element_info = ring_tail << WQ_RING_TAIL_SHIFT;
        GEM_BUG_ON(ring_tail > WQ_RING_TAIL_MAX);
        wqi->fence_id = fence_id;

        /* Make the update visible to GuC */
        WRITE_ONCE(desc->tail, (wq_off + wqi_size) & (GUC_WQ_SIZE - 1));
}

static void guc_add_request(struct intel_guc *guc, struct i915_request *rq)
{
        struct intel_engine_cs *engine = rq->engine;
        u32 ctx_desc = rq->context->lrc.ccid;
        u32 ring_tail = intel_ring_set_tail(rq->ring, rq->tail) / sizeof(u64);

        guc_wq_item_append(guc, engine->guc_id, ctx_desc,
                           ring_tail, rq->fence.seqno);
}

/*
 * When we're doing submissions using regular execlists backend, writing to
 * ELSP from CPU side is enough to make sure that writes to ringbuffer pages
 * pinned in mappable aperture portion of GGTT are visible to command streamer.
 * Writes done by GuC on our behalf are not guaranteeing such ordering,
 * therefore, to ensure the flush, we're issuing a POSTING READ.
 */
static void flush_ggtt_writes(struct i915_vma *vma)
{
        if (i915_vma_is_map_and_fenceable(vma))
                intel_uncore_posting_read_fw(vma->vm->gt->uncore,
                                             GUC_STATUS);
}

static void guc_submit(struct intel_engine_cs *engine,
                       struct i915_request **out,
                       struct i915_request **end)
{
        struct intel_guc *guc = &engine->gt->uc.guc;

        spin_lock(&guc->wq_lock);

        do {
                struct i915_request *rq = *out++;

                flush_ggtt_writes(rq->ring->vma);
                guc_add_request(guc, rq);
        } while (out != end);

        spin_unlock(&guc->wq_lock);
}

static inline int rq_prio(const struct i915_request *rq)
{
        return rq->sched.attr.priority;
}

static struct i915_request *schedule_in(struct i915_request *rq, int idx)
{
        trace_i915_request_in(rq, idx);

        /*
         * Currently we are not tracking the rq->context being inflight
         * (ce->inflight = rq->engine). It is only used by the execlists
         * backend at the moment, a similar counting strategy would be
         * required if we generalise the inflight tracking.
         */

        __intel_gt_pm_get(rq->engine->gt);
        return i915_request_get(rq);
}

static void schedule_out(struct i915_request *rq)
{
        trace_i915_request_out(rq);

        intel_gt_pm_put_async(rq->engine->gt);
        i915_request_put(rq);
}

static void __guc_dequeue(struct intel_engine_cs *engine)
{
        struct intel_engine_execlists * const execlists = &engine->execlists;
        struct i915_request **first = execlists->inflight;
        struct i915_request ** const last_port = first + execlists->port_mask;
        struct i915_request *last = first[0];
        struct i915_request **port;
        bool submit = false;
        struct rb_node *rb;

        lockdep_assert_held(&engine->active.lock);

        if (last) {
                if (*++first)
                        return;

                last = NULL;
        }

        /*
         * We write directly into the execlists->inflight queue and don't use
         * the execlists->pending queue, as we don't have a distinct switch
         * event.
         */
        port = first;
        while ((rb = rb_first_cached(&execlists->queue))) {
                struct i915_priolist *p = to_priolist(rb);
                struct i915_request *rq, *rn;
                int i;

                priolist_for_each_request_consume(rq, rn, p, i) {
                        if (last && rq->context != last->context) {
                                if (port == last_port)
                                        goto done;

                                *port = schedule_in(last,
                                                    port - execlists->inflight);
                                port++;
                        }

                        list_del_init(&rq->sched.link);
                        __i915_request_submit(rq);
                        submit = true;
                        last = rq;
                }

                rb_erase_cached(&p->node, &execlists->queue);
                i915_priolist_free(p);
        }
done:
        execlists->queue_priority_hint =
                rb ? to_priolist(rb)->priority : INT_MIN;
        if (submit) {
                *port = schedule_in(last, port - execlists->inflight);
                *++port = NULL;
                guc_submit(engine, first, port);
        }
        execlists->active = execlists->inflight;
}

static void guc_submission_tasklet(unsigned long data)
{
        struct intel_engine_cs * const engine = (struct intel_engine_cs *)data;
        struct intel_engine_execlists * const execlists = &engine->execlists;
        struct i915_request **port, *rq;
        unsigned long flags;

        spin_lock_irqsave(&engine->active.lock, flags);

        for (port = execlists->inflight; (rq = *port); port++) {
                if (!i915_request_completed(rq))
                        break;

                schedule_out(rq);
        }
        if (port != execlists->inflight) {
                int idx = port - execlists->inflight;
                int rem = ARRAY_SIZE(execlists->inflight) - idx;
                memmove(execlists->inflight, port, rem * sizeof(*port));
        }

        __guc_dequeue(engine);

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

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

        ENGINE_TRACE(engine, "\n");

        /*
         * Prevent request submission to the hardware until we have
         * completed the reset in i915_gem_reset_finish(). If a request
         * is completed by one engine, it may then queue a request
         * to a second via its execlists->tasklet *just* as we are
         * calling engine->init_hw() and also writing the ELSP.
         * Turning off the execlists->tasklet until the reset is over
         * prevents the race.
         */
        __tasklet_disable_sync_once(&execlists->tasklet);
}

static void
cancel_port_requests(struct intel_engine_execlists * const execlists)
{
        struct i915_request * const *port, *rq;

        /* Note we are only using the inflight and not the pending queue */

        for (port = execlists->active; (rq = *port); port++)
                schedule_out(rq);
        execlists->active =
                memset(execlists->inflight, 0, sizeof(execlists->inflight));
}

static void guc_reset_rewind(struct intel_engine_cs *engine, bool stalled)
{
        struct intel_engine_execlists * const execlists = &engine->execlists;
        struct i915_request *rq;
        unsigned long flags;

        spin_lock_irqsave(&engine->active.lock, flags);

        cancel_port_requests(execlists);

        /* Push back any incomplete requests for replay after the reset. */
        rq = execlists_unwind_incomplete_requests(execlists);
        if (!rq)
                goto out_unlock;

        if (!i915_request_started(rq))
                stalled = false;

        __i915_request_reset(rq, stalled);
        intel_lr_context_reset(engine, rq->context, rq->head, stalled);

out_unlock:
        spin_unlock_irqrestore(&engine->active.lock, flags);
}

static void guc_reset_cancel(struct intel_engine_cs *engine)
{
        struct intel_engine_execlists * const execlists = &engine->execlists;
        struct i915_request *rq, *rn;
        struct rb_node *rb;
        unsigned long flags;

        ENGINE_TRACE(engine, "\n");

        /*
         * Before we call engine->cancel_requests(), we should have exclusive
         * access to the submission state. This is arranged for us by the
         * caller disabling the interrupt generation, the tasklet and other
         * threads that may then access the same state, giving us a free hand
         * to reset state. However, we still need to let lockdep be aware that
         * we know this state may be accessed in hardirq context, so we
         * disable the irq around this manipulation and we want to keep
         * the spinlock focused on its duties and not accidentally conflate
         * coverage to the submission's irq state. (Similarly, although we
         * shouldn't need to disable irq around the manipulation of the
         * submission's irq state, we also wish to remind ourselves that
         * it is irq state.)
         */
        spin_lock_irqsave(&engine->active.lock, flags);

        /* Cancel the requests on the HW and clear the ELSP tracker. */
        cancel_port_requests(execlists);

        /* Mark all executing requests as skipped. */
        list_for_each_entry(rq, &engine->active.requests, sched.link) {
                i915_request_set_error_once(rq, -EIO);
                i915_request_mark_complete(rq);
        }

        /* Flush the queued requests to the timeline list (for retiring). */
        while ((rb = rb_first_cached(&execlists->queue))) {
                struct i915_priolist *p = to_priolist(rb);
                int i;

                priolist_for_each_request_consume(rq, rn, p, i) {
                        list_del_init(&rq->sched.link);
                        __i915_request_submit(rq);
                        dma_fence_set_error(&rq->fence, -EIO);
                        i915_request_mark_complete(rq);
                }

                rb_erase_cached(&p->node, &execlists->queue);
                i915_priolist_free(p);
        }

        /* Remaining _unready_ requests will be nop'ed when submitted */

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

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

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

        if (__tasklet_enable(&execlists->tasklet))
                /* And kick in case we missed a new request submission. */
                tasklet_hi_schedule(&execlists->tasklet);

        ENGINE_TRACE(engine, "depth->%d\n",
                     atomic_read(&execlists->tasklet.count));
}

/*
 * Everything below here is concerned with setup & teardown, and is
 * therefore not part of the somewhat time-critical batch-submission
 * path of guc_submit() above.
 */

/*
 * Set up the memory resources to be shared with the GuC (via the GGTT)
 * at firmware loading time.
 */
int intel_guc_submission_init(struct intel_guc *guc)
{
        int ret;

        if (guc->stage_desc_pool)
                return 0;

        ret = guc_stage_desc_pool_create(guc);
        if (ret)
                return ret;
        /*
         * Keep static analysers happy, let them know that we allocated the
         * vma after testing that it didn't exist earlier.
         */
        GEM_BUG_ON(!guc->stage_desc_pool);

        ret = guc_workqueue_create(guc);
        if (ret)
                goto err_pool;

        ret = guc_proc_desc_create(guc);
        if (ret)
                goto err_workqueue;

        spin_lock_init(&guc->wq_lock);

        return 0;

err_workqueue:
        guc_workqueue_destroy(guc);
err_pool:
        guc_stage_desc_pool_destroy(guc);
        return ret;
}

void intel_guc_submission_fini(struct intel_guc *guc)
{
        if (guc->stage_desc_pool) {
                guc_proc_desc_destroy(guc);
                guc_workqueue_destroy(guc);
                guc_stage_desc_pool_destroy(guc);
        }
}

static void guc_interrupts_capture(struct intel_gt *gt)
{
        struct intel_uncore *uncore = gt->uncore;
        u32 irqs = GT_CONTEXT_SWITCH_INTERRUPT;
        u32 dmask = irqs << 16 | irqs;

        GEM_BUG_ON(INTEL_GEN(gt->i915) < 11);

        /* Don't handle the ctx switch interrupt in GuC submission mode */
        intel_uncore_rmw(uncore, GEN11_RENDER_COPY_INTR_ENABLE, dmask, 0);
        intel_uncore_rmw(uncore, GEN11_VCS_VECS_INTR_ENABLE, dmask, 0);
}

static void guc_interrupts_release(struct intel_gt *gt)
{
        struct intel_uncore *uncore = gt->uncore;
        u32 irqs = GT_CONTEXT_SWITCH_INTERRUPT;
        u32 dmask = irqs << 16 | irqs;

        GEM_BUG_ON(INTEL_GEN(gt->i915) < 11);

        /* Handle ctx switch interrupts again */
        intel_uncore_rmw(uncore, GEN11_RENDER_COPY_INTR_ENABLE, 0, dmask);
        intel_uncore_rmw(uncore, GEN11_VCS_VECS_INTR_ENABLE, 0, dmask);
}

static void guc_set_default_submission(struct intel_engine_cs *engine)
{
        /*
         * We inherit a bunch of functions from execlists that we'd like
         * to keep using:
         *
         *    engine->submit_request = execlists_submit_request;
         *    engine->cancel_requests = execlists_cancel_requests;
         *    engine->schedule = execlists_schedule;
         *
         * But we need to override the actual submission backend in order
         * to talk to the GuC.
         */
        intel_execlists_set_default_submission(engine);

        engine->execlists.tasklet.func = guc_submission_tasklet;

        /* do not use execlists park/unpark */
        engine->park = engine->unpark = NULL;

        engine->reset.prepare = guc_reset_prepare;
        engine->reset.rewind = guc_reset_rewind;
        engine->reset.cancel = guc_reset_cancel;
        engine->reset.finish = guc_reset_finish;

        engine->flags &= ~I915_ENGINE_SUPPORTS_STATS;
        engine->flags |= I915_ENGINE_NEEDS_BREADCRUMB_TASKLET;

        /*
         * For the breadcrumb irq to work we need the interrupts to stay
         * enabled. However, on all platforms on which we'll have support for
         * GuC submission we don't allow disabling the interrupts at runtime, so
         * we're always safe with the current flow.
         */
        GEM_BUG_ON(engine->irq_enable || engine->irq_disable);
}

void intel_guc_submission_enable(struct intel_guc *guc)
{
        struct intel_gt *gt = guc_to_gt(guc);
        struct intel_engine_cs *engine;
        enum intel_engine_id id;

        /*
         * We're using GuC work items for submitting work through GuC. Since
         * we're coalescing multiple requests from a single context into a
         * single work item prior to assigning it to execlist_port, we can
         * never have more work items than the total number of ports (for all
         * engines). The GuC firmware is controlling the HEAD of work queue,
         * and it is guaranteed that it will remove the work item from the
         * queue before our request is completed.
         */
        BUILD_BUG_ON(ARRAY_SIZE(engine->execlists.inflight) *
                     sizeof(struct guc_wq_item) *
                     I915_NUM_ENGINES > GUC_WQ_SIZE);

        guc_proc_desc_init(guc);
        guc_stage_desc_init(guc);

        /* Take over from manual control of ELSP (execlists) */
        guc_interrupts_capture(gt);

        for_each_engine(engine, gt, id) {
                engine->set_default_submission = guc_set_default_submission;
                engine->set_default_submission(engine);
        }
}

void intel_guc_submission_disable(struct intel_guc *guc)
{
        struct intel_gt *gt = guc_to_gt(guc);

        GEM_BUG_ON(gt->awake); /* GT should be parked first */

        /* Note: By the time we're here, GuC may have already been reset */

        guc_interrupts_release(gt);

        guc_stage_desc_fini(guc);
        guc_proc_desc_fini(guc);
}

static bool __guc_submission_selected(struct intel_guc *guc)
{
        struct drm_i915_private *i915 = guc_to_gt(guc)->i915;

        if (!intel_guc_submission_is_supported(guc))
                return false;

        return i915->params.enable_guc & ENABLE_GUC_SUBMISSION;
}

void intel_guc_submission_init_early(struct intel_guc *guc)
{
        guc->submission_selected = __guc_submission_selected(guc);
}

bool intel_engine_in_guc_submission_mode(const struct intel_engine_cs *engine)
{
        return engine->set_default_submission == guc_set_default_submission;
}