drm/i915: Track pinned vma inside guc

[deliverable/linux.git] / drivers / gpu / drm / i915 / i915_guc_submission.c

/*
 * Copyright © 2014 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 <linux/firmware.h>
#include <linux/circ_buf.h>
#include "i915_drv.h"
#include "intel_guc.h"

/**
 * DOC: GuC-based command submission
 *
 * i915_guc_client:
 * We use the term client to avoid confusion with contexts. A i915_guc_client is
 * equivalent to GuC object guc_context_desc. This context descriptor is
 * allocated from a pool of 1024 entries. Kernel driver will allocate doorbell
 * and workqueue for it. Also the process descriptor (guc_process_desc), which
 * is mapped to client space. So the client can write Work Item then ring the
 * doorbell.
 *
 * To simplify the implementation, we allocate one gem object that contains all
 * pages for doorbell, process descriptor and workqueue.
 *
 * 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.
 * See host2guc_action()
 *
 * Doorbells:
 * Doorbells are interrupts to uKernel. A doorbell is a single cache line (QW)
 * mapped into process space.
 *
 * 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_workqueue_item()
 *
 */

/*
 * Read GuC command/status register (SOFT_SCRATCH_0)
 * Return true if it contains a response rather than a command
 */
static inline bool host2guc_action_response(struct drm_i915_private *dev_priv,
                                            u32 *status)
{
        u32 val = I915_READ(SOFT_SCRATCH(0));
        *status = val;
        return GUC2HOST_IS_RESPONSE(val);
}

static int host2guc_action(struct intel_guc *guc, u32 *data, u32 len)
{
        struct drm_i915_private *dev_priv = guc_to_i915(guc);
        u32 status;
        int i;
        int ret;

        if (WARN_ON(len < 1 || len > 15))
                return -EINVAL;

        intel_uncore_forcewake_get(dev_priv, FORCEWAKE_ALL);

        dev_priv->guc.action_count += 1;
        dev_priv->guc.action_cmd = data[0];

        for (i = 0; i < len; i++)
                I915_WRITE(SOFT_SCRATCH(i), data[i]);

        POSTING_READ(SOFT_SCRATCH(i - 1));

        I915_WRITE(HOST2GUC_INTERRUPT, HOST2GUC_TRIGGER);

        /*
         * Fast commands should complete in less than 10us, so sample quickly
         * up to that length of time, then switch to a slower sleep-wait loop.
         * No HOST2GUC command should ever take longer than 10ms.
         */
        ret = wait_for_us(host2guc_action_response(dev_priv, &status), 10);
        if (ret)
                ret = wait_for(host2guc_action_response(dev_priv, &status), 10);
        if (status != GUC2HOST_STATUS_SUCCESS) {
                /*
                 * Either the GuC explicitly returned an error (which
                 * we convert to -EIO here) or no response at all was
                 * received within the timeout limit (-ETIMEDOUT)
                 */
                if (ret != -ETIMEDOUT)
                        ret = -EIO;

                DRM_ERROR("GUC: host2guc action 0x%X failed. ret=%d "
                                "status=0x%08X response=0x%08X\n",
                                data[0], ret, status,
                                I915_READ(SOFT_SCRATCH(15)));

                dev_priv->guc.action_fail += 1;
                dev_priv->guc.action_err = ret;
        }
        dev_priv->guc.action_status = status;

        intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);

        return ret;
}

/*
 * Tell the GuC to allocate or deallocate a specific doorbell
 */

static int host2guc_allocate_doorbell(struct intel_guc *guc,
                                      struct i915_guc_client *client)
{
        u32 data[2];

        data[0] = HOST2GUC_ACTION_ALLOCATE_DOORBELL;
        data[1] = client->ctx_index;

        return host2guc_action(guc, data, 2);
}

static int host2guc_release_doorbell(struct intel_guc *guc,
                                     struct i915_guc_client *client)
{
        u32 data[2];

        data[0] = HOST2GUC_ACTION_DEALLOCATE_DOORBELL;
        data[1] = client->ctx_index;

        return host2guc_action(guc, data, 2);
}

static int host2guc_sample_forcewake(struct intel_guc *guc,
                                     struct i915_guc_client *client)
{
        struct drm_i915_private *dev_priv = guc_to_i915(guc);
        u32 data[2];

        data[0] = HOST2GUC_ACTION_SAMPLE_FORCEWAKE;
        /* WaRsDisableCoarsePowerGating:skl,bxt */
        if (!intel_enable_rc6() || NEEDS_WaRsDisableCoarsePowerGating(dev_priv))
                data[1] = 0;
        else
                /* bit 0 and 1 are for Render and Media domain separately */
                data[1] = GUC_FORCEWAKE_RENDER | GUC_FORCEWAKE_MEDIA;

        return host2guc_action(guc, data, ARRAY_SIZE(data));
}

/*
 * Initialise, update, or clear doorbell data shared with the GuC
 *
 * These functions modify shared data and so need access to the mapped
 * client object which contains the page being used for the doorbell
 */

static int guc_update_doorbell_id(struct intel_guc *guc,
                                  struct i915_guc_client *client,
                                  u16 new_id)
{
        struct sg_table *sg = guc->ctx_pool_vma->pages;
        void *doorbell_bitmap = guc->doorbell_bitmap;
        struct guc_doorbell_info *doorbell;
        struct guc_context_desc desc;
        size_t len;

        doorbell = client->client_base + client->doorbell_offset;

        if (client->doorbell_id != GUC_INVALID_DOORBELL_ID &&
            test_bit(client->doorbell_id, doorbell_bitmap)) {
                /* Deactivate the old doorbell */
                doorbell->db_status = GUC_DOORBELL_DISABLED;
                (void)host2guc_release_doorbell(guc, client);
                __clear_bit(client->doorbell_id, doorbell_bitmap);
        }

        /* Update the GuC's idea of the doorbell ID */
        len = sg_pcopy_to_buffer(sg->sgl, sg->nents, &desc, sizeof(desc),
                             sizeof(desc) * client->ctx_index);
        if (len != sizeof(desc))
                return -EFAULT;
        desc.db_id = new_id;
        len = sg_pcopy_from_buffer(sg->sgl, sg->nents, &desc, sizeof(desc),
                             sizeof(desc) * client->ctx_index);
        if (len != sizeof(desc))
                return -EFAULT;

        client->doorbell_id = new_id;
        if (new_id == GUC_INVALID_DOORBELL_ID)
                return 0;

        /* Activate the new doorbell */
        __set_bit(new_id, doorbell_bitmap);
        doorbell->cookie = 0;
        doorbell->db_status = GUC_DOORBELL_ENABLED;
        return host2guc_allocate_doorbell(guc, client);
}

static int guc_init_doorbell(struct intel_guc *guc,
                              struct i915_guc_client *client,
                              uint16_t db_id)
{
        return guc_update_doorbell_id(guc, client, db_id);
}

static void guc_disable_doorbell(struct intel_guc *guc,
                                 struct i915_guc_client *client)
{
        (void)guc_update_doorbell_id(guc, client, GUC_INVALID_DOORBELL_ID);

        /* XXX: wait for any interrupts */
        /* XXX: wait for workqueue to drain */
}

static uint16_t
select_doorbell_register(struct intel_guc *guc, uint32_t priority)
{
        /*
         * The bitmap tracks which doorbell registers are currently in use.
         * It is split into two halves; the first half is used for normal
         * priority contexts, the second half for high-priority ones.
         * Note that logically higher priorities are numerically less than
         * normal ones, so the test below means "is it high-priority?"
         */
        const bool hi_pri = (priority <= GUC_CTX_PRIORITY_HIGH);
        const uint16_t half = GUC_MAX_DOORBELLS / 2;
        const uint16_t start = hi_pri ? half : 0;
        const uint16_t end = start + half;
        uint16_t id;

        id = find_next_zero_bit(guc->doorbell_bitmap, end, start);
        if (id == end)
                id = GUC_INVALID_DOORBELL_ID;

        DRM_DEBUG_DRIVER("assigned %s priority doorbell id 0x%x\n",
                        hi_pri ? "high" : "normal", id);

        return id;
}

/*
 * Select, assign and relase doorbell cachelines
 *
 * These functions track which doorbell cachelines are in use.
 * The data they manipulate is protected by the host2guc lock.
 */

static uint32_t select_doorbell_cacheline(struct intel_guc *guc)
{
        const uint32_t cacheline_size = cache_line_size();
        uint32_t offset;

        /* Doorbell uses a single cache line within a page */
        offset = offset_in_page(guc->db_cacheline);

        /* Moving to next cache line to reduce contention */
        guc->db_cacheline += cacheline_size;

        DRM_DEBUG_DRIVER("selected doorbell cacheline 0x%x, next 0x%x, linesize %u\n",
                        offset, guc->db_cacheline, cacheline_size);

        return offset;
}

/*
 * Initialise the process descriptor shared with the GuC firmware.
 */
static void guc_init_proc_desc(struct intel_guc *guc,
                               struct i915_guc_client *client)
{
        struct guc_process_desc *desc;

        desc = client->client_base + client->proc_desc_offset;

        memset(desc, 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->context_id = client->ctx_index;
        desc->wq_size_bytes = client->wq_size;
        desc->wq_status = WQ_STATUS_ACTIVE;
        desc->priority = client->priority;
}

/*
 * Initialise/clear the context descriptor shared with the GuC firmware.
 *
 * This descriptor tells the GuC where (in GGTT space) to find the important
 * data structures relating to this client (doorbell, process descriptor,
 * write queue, etc).
 */

static void guc_init_ctx_desc(struct intel_guc *guc,
                              struct i915_guc_client *client)
{
        struct drm_i915_private *dev_priv = guc_to_i915(guc);
        struct intel_engine_cs *engine;
        struct i915_gem_context *ctx = client->owner;
        struct guc_context_desc desc;
        struct sg_table *sg;
        u32 gfx_addr;

        memset(&desc, 0, sizeof(desc));

        desc.attribute = GUC_CTX_DESC_ATTR_ACTIVE | GUC_CTX_DESC_ATTR_KERNEL;
        desc.context_id = client->ctx_index;
        desc.priority = client->priority;
        desc.db_id = client->doorbell_id;

        for_each_engine_masked(engine, dev_priv, client->engines) {
                struct intel_context *ce = &ctx->engine[engine->id];
                uint32_t guc_engine_id = engine->guc_id;
                struct guc_execlist_context *lrc = &desc.lrc[guc_engine_id];
                struct drm_i915_gem_object *obj;

                /* TODO: We have a design issue to be solved here. Only when we
                 * receive the first batch, we know which engine is used by the
                 * user. But here GuC expects the lrc and ring to be pinned. It
                 * is not an issue for default context, which is the only one
                 * for now who owns a GuC client. But for future owner of GuC
                 * client, need to make sure lrc is pinned prior to enter here.
                 */
                if (!ce->state)
                        break;  /* XXX: continue? */

                lrc->context_desc = lower_32_bits(ce->lrc_desc);

                /* The state page is after PPHWSP */
                gfx_addr = i915_gem_obj_ggtt_offset(ce->state);
                lrc->ring_lcra = gfx_addr + LRC_STATE_PN * PAGE_SIZE;
                lrc->context_id = (client->ctx_index << GUC_ELC_CTXID_OFFSET) |
                                (guc_engine_id << GUC_ELC_ENGINE_OFFSET);

                obj = ce->ring->obj;
                gfx_addr = i915_gem_obj_ggtt_offset(obj);

                lrc->ring_begin = gfx_addr;
                lrc->ring_end = gfx_addr + obj->base.size - 1;
                lrc->ring_next_free_location = gfx_addr;
                lrc->ring_current_tail_pointer_value = 0;

                desc.engines_used |= (1 << guc_engine_id);
        }

        DRM_DEBUG_DRIVER("Host engines 0x%x => GuC engines used 0x%x\n",
                        client->engines, desc.engines_used);
        WARN_ON(desc.engines_used == 0);

        /*
         * The doorbell, process descriptor, and workqueue are all parts
         * of the client object, which the GuC will reference via the GGTT
         */
        gfx_addr = client->vma->node.start;
        desc.db_trigger_phy = sg_dma_address(client->vma->pages->sgl) +
                                client->doorbell_offset;
        desc.db_trigger_cpu = (uintptr_t)client->client_base +
                                client->doorbell_offset;
        desc.db_trigger_uk = gfx_addr + client->doorbell_offset;
        desc.process_desc = gfx_addr + client->proc_desc_offset;
        desc.wq_addr = gfx_addr + client->wq_offset;
        desc.wq_size = client->wq_size;

        /*
         * XXX: Take LRCs from an existing context if this is not an
         * IsKMDCreatedContext client
         */
        desc.desc_private = (uintptr_t)client;

        /* Pool context is pinned already */
        sg = guc->ctx_pool_vma->pages;
        sg_pcopy_from_buffer(sg->sgl, sg->nents, &desc, sizeof(desc),
                             sizeof(desc) * client->ctx_index);
}

static void guc_fini_ctx_desc(struct intel_guc *guc,
                              struct i915_guc_client *client)
{
        struct guc_context_desc desc;
        struct sg_table *sg;

        memset(&desc, 0, sizeof(desc));

        sg = guc->ctx_pool_vma->pages;
        sg_pcopy_from_buffer(sg->sgl, sg->nents, &desc, sizeof(desc),
                             sizeof(desc) * client->ctx_index);
}

/**
 * i915_guc_wq_check_space() - check that the GuC can accept a request
 * @request:    request associated with the commands
 *
 * Return:      0 if space is available
 *              -EAGAIN if space is not currently available
 *
 * This function must be called (and must return 0) before a request
 * is submitted to the GuC via i915_guc_submit() below. Once a result
 * of 0 has been returned, it remains valid until (but only until)
 * the next call to submit().
 *
 * This precheck allows the caller to determine in advance that space
 * will be available for the next submission before committing resources
 * to it, and helps avoid late failures with complicated recovery paths.
 */
int i915_guc_wq_check_space(struct drm_i915_gem_request *request)
{
        const size_t wqi_size = sizeof(struct guc_wq_item);
        struct i915_guc_client *gc = request->i915->guc.execbuf_client;
        struct guc_process_desc *desc;
        u32 freespace;

        GEM_BUG_ON(gc == NULL);

        desc = gc->client_base + gc->proc_desc_offset;

        freespace = CIRC_SPACE(gc->wq_tail, desc->head, gc->wq_size);
        if (likely(freespace >= wqi_size))
                return 0;

        gc->no_wq_space += 1;

        return -EAGAIN;
}

static void guc_add_workqueue_item(struct i915_guc_client *gc,
                                   struct drm_i915_gem_request *rq)
{
        /* 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 intel_engine_cs *engine = rq->engine;
        struct guc_process_desc *desc;
        struct guc_wq_item *wqi;
        void *base;
        u32 freespace, tail, wq_off, wq_page;

        desc = gc->client_base + gc->proc_desc_offset;

        /* Free space is guaranteed, see i915_guc_wq_check_space() above */
        freespace = CIRC_SPACE(gc->wq_tail, desc->head, gc->wq_size);
        GEM_BUG_ON(freespace < wqi_size);

        /* The GuC firmware wants the tail index in QWords, not bytes */
        tail = rq->tail;
        GEM_BUG_ON(tail & 7);
        tail >>= 3;
        GEM_BUG_ON(tail > WQ_RING_TAIL_MAX);

        /* 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);

        /* postincrement WQ tail for next time */
        wq_off = gc->wq_tail;
        gc->wq_tail += wqi_size;
        gc->wq_tail &= gc->wq_size - 1;
        GEM_BUG_ON(wq_off & (wqi_size - 1));

        /* WQ starts from the page after doorbell / process_desc */
        wq_page = (wq_off + GUC_DB_SIZE) >> PAGE_SHIFT;
        wq_off &= PAGE_SIZE - 1;
        base = kmap_atomic(i915_gem_object_get_page(gc->vma->obj, wq_page));
        wqi = (struct guc_wq_item *)((char *)base + wq_off);

        /* Now fill in the 4-word work queue item */
        wqi->header = WQ_TYPE_INORDER |
                        (wqi_len << WQ_LEN_SHIFT) |
                        (engine->guc_id << WQ_TARGET_SHIFT) |
                        WQ_NO_WCFLUSH_WAIT;

        /* The GuC wants only the low-order word of the context descriptor */
        wqi->context_desc = (u32)intel_lr_context_descriptor(rq->ctx, engine);

        wqi->ring_tail = tail << WQ_RING_TAIL_SHIFT;
        wqi->fence_id = rq->fence.seqno;

        kunmap_atomic(base);
}

static int guc_ring_doorbell(struct i915_guc_client *gc)
{
        struct guc_process_desc *desc;
        union guc_doorbell_qw db_cmp, db_exc, db_ret;
        union guc_doorbell_qw *db;
        int attempt = 2, ret = -EAGAIN;

        desc = gc->client_base + gc->proc_desc_offset;

        /* Update the tail so it is visible to GuC */
        desc->tail = gc->wq_tail;

        /* current cookie */
        db_cmp.db_status = GUC_DOORBELL_ENABLED;
        db_cmp.cookie = gc->cookie;

        /* cookie to be updated */
        db_exc.db_status = GUC_DOORBELL_ENABLED;
        db_exc.cookie = gc->cookie + 1;
        if (db_exc.cookie == 0)
                db_exc.cookie = 1;

        /* pointer of current doorbell cacheline */
        db = gc->client_base + gc->doorbell_offset;

        while (attempt--) {
                /* lets ring the doorbell */
                db_ret.value_qw = atomic64_cmpxchg((atomic64_t *)db,
                        db_cmp.value_qw, db_exc.value_qw);

                /* if the exchange was successfully executed */
                if (db_ret.value_qw == db_cmp.value_qw) {
                        /* db was successfully rung */
                        gc->cookie = db_exc.cookie;
                        ret = 0;
                        break;
                }

                /* XXX: doorbell was lost and need to acquire it again */
                if (db_ret.db_status == GUC_DOORBELL_DISABLED)
                        break;

                DRM_ERROR("Cookie mismatch. Expected %d, returned %d\n",
                          db_cmp.cookie, db_ret.cookie);

                /* update the cookie to newly read cookie from GuC */
                db_cmp.cookie = db_ret.cookie;
                db_exc.cookie = db_ret.cookie + 1;
                if (db_exc.cookie == 0)
                        db_exc.cookie = 1;
        }

        return ret;
}

/**
 * i915_guc_submit() - Submit commands through GuC
 * @rq:         request associated with the commands
 *
 * Return:      0 on success, otherwise an errno.
 *              (Note: nonzero really shouldn't happen!)
 *
 * The caller must have already called i915_guc_wq_check_space() above
 * with a result of 0 (success) since the last request submission. This
 * guarantees that there is space in the work queue for the new request,
 * so enqueuing the item cannot fail.
 *
 * Bad Things Will Happen if the caller violates this protocol e.g. calls
 * submit() when check() says there's no space, or calls submit() multiple
 * times with no intervening check().
 *
 * The only error here arises if the doorbell hardware isn't functioning
 * as expected, which really shouln't happen.
 */
static void i915_guc_submit(struct drm_i915_gem_request *rq)
{
        unsigned int engine_id = rq->engine->id;
        struct intel_guc *guc = &rq->i915->guc;
        struct i915_guc_client *client = guc->execbuf_client;
        int b_ret;

        guc_add_workqueue_item(client, rq);
        b_ret = guc_ring_doorbell(client);

        client->submissions[engine_id] += 1;
        client->retcode = b_ret;
        if (b_ret)
                client->b_fail += 1;

        guc->submissions[engine_id] += 1;
        guc->last_seqno[engine_id] = rq->fence.seqno;
}

/*
 * Everything below here is concerned with setup & teardown, and is
 * therefore not part of the somewhat time-critical batch-submission
 * path of i915_guc_submit() above.
 */

/**
 * guc_allocate_vma() - Allocate a GGTT VMA for GuC usage
 * @guc:        the guc
 * @size:       size of area to allocate (both virtual space and memory)
 *
 * This is a wrapper to create an object for use with the GuC. In order to
 * use it inside the GuC, an object needs to be pinned lifetime, so we allocate
 * both some backing storage and a range inside the Global GTT. We must pin
 * it in the GGTT somewhere other than than [0, GUC_WOPCM_TOP) because that
 * range is reserved inside GuC.
 *
 * Return:      A i915_vma if successful, otherwise an ERR_PTR.
 */
static struct i915_vma *guc_allocate_vma(struct intel_guc *guc, u32 size)
{
        struct drm_i915_private *dev_priv = guc_to_i915(guc);
        struct drm_i915_gem_object *obj;
        struct i915_vma *vma;
        int ret;

        obj = i915_gem_object_create(&dev_priv->drm, size);
        if (IS_ERR(obj))
                return ERR_CAST(obj);

        vma = i915_vma_create(obj, &dev_priv->ggtt.base, NULL);
        if (IS_ERR(vma))
                goto err;

        ret = i915_vma_pin(vma, 0, PAGE_SIZE,
                           PIN_GLOBAL | PIN_OFFSET_BIAS | GUC_WOPCM_TOP);
        if (ret) {
                vma = ERR_PTR(ret);
                goto err;
        }

        /* Invalidate GuC TLB to let GuC take the latest updates to GTT. */
        I915_WRITE(GEN8_GTCR, GEN8_GTCR_INVALIDATE);

        return vma;

err:
        i915_gem_object_put(obj);
        return vma;
}

/**
 * guc_release_vma() - Release gem object allocated for GuC usage
 * @vma:        gem obj to be released
 */
static void guc_release_vma(struct i915_vma *vma)
{
        if (!vma)
                return;

        i915_vma_unpin(vma);
        i915_vma_put(vma);
}

static void
guc_client_free(struct drm_i915_private *dev_priv,
                struct i915_guc_client *client)
{
        struct intel_guc *guc = &dev_priv->guc;

        if (!client)
                return;

        /*
         * XXX: wait for any outstanding submissions before freeing memory.
         * Be sure to drop any locks
         */

        if (client->client_base) {
                /*
                 * If we got as far as setting up a doorbell, make sure we
                 * shut it down before unmapping & deallocating the memory.
                 */
                guc_disable_doorbell(guc, client);

                kunmap(kmap_to_page(client->client_base));
        }

        guc_release_vma(client->vma);

        if (client->ctx_index != GUC_INVALID_CTX_ID) {
                guc_fini_ctx_desc(guc, client);
                ida_simple_remove(&guc->ctx_ids, client->ctx_index);
        }

        kfree(client);
}

/* Check that a doorbell register is in the expected state */
static bool guc_doorbell_check(struct intel_guc *guc, uint16_t db_id)
{
        struct drm_i915_private *dev_priv = guc_to_i915(guc);
        i915_reg_t drbreg = GEN8_DRBREGL(db_id);
        uint32_t value = I915_READ(drbreg);
        bool enabled = (value & GUC_DOORBELL_ENABLED) != 0;
        bool expected = test_bit(db_id, guc->doorbell_bitmap);

        if (enabled == expected)
                return true;

        DRM_DEBUG_DRIVER("Doorbell %d (reg 0x%x) 0x%x, should be %s\n",
                         db_id, drbreg.reg, value,
                         expected ? "active" : "inactive");

        return false;
}

/*
 * Borrow the first client to set up & tear down each unused doorbell
 * in turn, to ensure that all doorbell h/w is (re)initialised.
 */
static void guc_init_doorbell_hw(struct intel_guc *guc)
{
        struct i915_guc_client *client = guc->execbuf_client;
        uint16_t db_id;
        int i, err;

        /* Save client's original doorbell selection */
        db_id = client->doorbell_id;

        for (i = 0; i < GUC_MAX_DOORBELLS; ++i) {
                /* Skip if doorbell is OK */
                if (guc_doorbell_check(guc, i))
                        continue;

                err = guc_update_doorbell_id(guc, client, i);
                if (err)
                        DRM_DEBUG_DRIVER("Doorbell %d update failed, err %d\n",
                                        i, err);
        }

        /* Restore to original value */
        err = guc_update_doorbell_id(guc, client, db_id);
        if (err)
                DRM_ERROR("Failed to restore doorbell to %d, err %d\n",
                        db_id, err);

        /* Read back & verify all doorbell registers */
        for (i = 0; i < GUC_MAX_DOORBELLS; ++i)
                (void)guc_doorbell_check(guc, i);
}

/**
 * guc_client_alloc() - Allocate an i915_guc_client
 * @dev_priv:   driver private data structure
 * @priority:   four levels priority _CRITICAL, _HIGH, _NORMAL and _LOW
 *              The kernel client to replace ExecList submission is created with
 *              NORMAL priority. Priority of a client for scheduler can be HIGH,
 *              while a preemption context can use CRITICAL.
 * @ctx:        the context that owns the client (we use the default render
 *              context)
 *
 * Return:      An i915_guc_client object if success, else NULL.
 */
static struct i915_guc_client *
guc_client_alloc(struct drm_i915_private *dev_priv,
                 uint32_t engines,
                 uint32_t priority,
                 struct i915_gem_context *ctx)
{
        struct i915_guc_client *client;
        struct intel_guc *guc = &dev_priv->guc;
        struct i915_vma *vma;
        uint16_t db_id;

        client = kzalloc(sizeof(*client), GFP_KERNEL);
        if (!client)
                return NULL;

        client->owner = ctx;
        client->guc = guc;
        client->engines = engines;
        client->priority = priority;
        client->doorbell_id = GUC_INVALID_DOORBELL_ID;

        client->ctx_index = (uint32_t)ida_simple_get(&guc->ctx_ids, 0,
                        GUC_MAX_GPU_CONTEXTS, GFP_KERNEL);
        if (client->ctx_index >= GUC_MAX_GPU_CONTEXTS) {
                client->ctx_index = GUC_INVALID_CTX_ID;
                goto err;
        }

        /* The first page is doorbell/proc_desc. Two followed pages are wq. */
        vma = guc_allocate_vma(guc, GUC_DB_SIZE + GUC_WQ_SIZE);
        if (IS_ERR(vma))
                goto err;

        /* We'll keep just the first (doorbell/proc) page permanently kmap'd. */
        client->vma = vma;
        client->client_base = kmap(i915_vma_first_page(vma));
        client->wq_offset = GUC_DB_SIZE;
        client->wq_size = GUC_WQ_SIZE;

        db_id = select_doorbell_register(guc, client->priority);
        if (db_id == GUC_INVALID_DOORBELL_ID)
                /* XXX: evict a doorbell instead? */
                goto err;

        client->doorbell_offset = select_doorbell_cacheline(guc);

        /*
         * Since the doorbell only requires a single cacheline, we can save
         * space by putting the application process descriptor in the same
         * page. Use the half of the page that doesn't include the doorbell.
         */
        if (client->doorbell_offset >= (GUC_DB_SIZE / 2))
                client->proc_desc_offset = 0;
        else
                client->proc_desc_offset = (GUC_DB_SIZE / 2);

        guc_init_proc_desc(guc, client);
        guc_init_ctx_desc(guc, client);
        if (guc_init_doorbell(guc, client, db_id))
                goto err;

        DRM_DEBUG_DRIVER("new priority %u client %p for engine(s) 0x%x: ctx_index %u\n",
                priority, client, client->engines, client->ctx_index);
        DRM_DEBUG_DRIVER("doorbell id %u, cacheline offset 0x%x\n",
                client->doorbell_id, client->doorbell_offset);

        return client;

err:
        DRM_ERROR("FAILED to create priority %u GuC client!\n", priority);

        guc_client_free(dev_priv, client);
        return NULL;
}

static void guc_create_log(struct intel_guc *guc)
{
        struct i915_vma *vma;
        unsigned long offset;
        uint32_t size, flags;

        if (i915.guc_log_level < GUC_LOG_VERBOSITY_MIN)
                return;

        if (i915.guc_log_level > GUC_LOG_VERBOSITY_MAX)
                i915.guc_log_level = GUC_LOG_VERBOSITY_MAX;

        /* The first page is to save log buffer state. Allocate one
         * extra page for others in case for overlap */
        size = (1 + GUC_LOG_DPC_PAGES + 1 +
                GUC_LOG_ISR_PAGES + 1 +
                GUC_LOG_CRASH_PAGES + 1) << PAGE_SHIFT;

        vma = guc->log_vma;
        if (!vma) {
                vma = guc_allocate_vma(guc, size);
                if (IS_ERR(vma)) {
                        /* logging will be off */
                        i915.guc_log_level = -1;
                        return;
                }

                guc->log_vma = vma;
        }

        /* each allocated unit is a page */
        flags = GUC_LOG_VALID | GUC_LOG_NOTIFY_ON_HALF_FULL |
                (GUC_LOG_DPC_PAGES << GUC_LOG_DPC_SHIFT) |
                (GUC_LOG_ISR_PAGES << GUC_LOG_ISR_SHIFT) |
                (GUC_LOG_CRASH_PAGES << GUC_LOG_CRASH_SHIFT);

        offset = vma->node.start >> PAGE_SHIFT; /* in pages */
        guc->log_flags = (offset << GUC_LOG_BUF_ADDR_SHIFT) | flags;
}

static void init_guc_policies(struct guc_policies *policies)
{
        struct guc_policy *policy;
        u32 p, i;

        policies->dpc_promote_time = 500000;
        policies->max_num_work_items = POLICY_MAX_NUM_WI;

        for (p = 0; p < GUC_CTX_PRIORITY_NUM; p++) {
                for (i = GUC_RENDER_ENGINE; i < GUC_MAX_ENGINES_NUM; i++) {
                        policy = &policies->policy[p][i];

                        policy->execution_quantum = 1000000;
                        policy->preemption_time = 500000;
                        policy->fault_time = 250000;
                        policy->policy_flags = 0;
                }
        }

        policies->is_valid = 1;
}

static void guc_create_ads(struct intel_guc *guc)
{
        struct drm_i915_private *dev_priv = guc_to_i915(guc);
        struct i915_vma *vma;
        struct guc_ads *ads;
        struct guc_policies *policies;
        struct guc_mmio_reg_state *reg_state;
        struct intel_engine_cs *engine;
        struct page *page;
        u32 size;

        /* The ads obj includes the struct itself and buffers passed to GuC */
        size = sizeof(struct guc_ads) + sizeof(struct guc_policies) +
                        sizeof(struct guc_mmio_reg_state) +
                        GUC_S3_SAVE_SPACE_PAGES * PAGE_SIZE;

        vma = guc->ads_vma;
        if (!vma) {
                vma = guc_allocate_vma(guc, PAGE_ALIGN(size));
                if (IS_ERR(vma))
                        return;

                guc->ads_vma = vma;
        }

        page = i915_vma_first_page(vma);
        ads = kmap(page);

        /*
         * The GuC requires a "Golden Context" when it reinitialises
         * engines after a reset. Here we use the Render ring default
         * context, which must already exist and be pinned in the GGTT,
         * so its address won't change after we've told the GuC where
         * to find it.
         */
        engine = &dev_priv->engine[RCS];
        ads->golden_context_lrca = engine->status_page.gfx_addr;

        for_each_engine(engine, dev_priv)
                ads->eng_state_size[engine->guc_id] = intel_lr_context_size(engine);

        /* GuC scheduling policies */
        policies = (void *)ads + sizeof(struct guc_ads);
        init_guc_policies(policies);

        ads->scheduler_policies = vma->node.start + sizeof(struct guc_ads);

        /* MMIO reg state */
        reg_state = (void *)policies + sizeof(struct guc_policies);

        for_each_engine(engine, dev_priv) {
                reg_state->mmio_white_list[engine->guc_id].mmio_start =
                        engine->mmio_base + GUC_MMIO_WHITE_LIST_START;

                /* Nothing to be saved or restored for now. */
                reg_state->mmio_white_list[engine->guc_id].count = 0;
        }

        ads->reg_state_addr = ads->scheduler_policies +
                        sizeof(struct guc_policies);

        ads->reg_state_buffer = ads->reg_state_addr +
                        sizeof(struct guc_mmio_reg_state);

        kunmap(page);
}

/*
 * Set up the memory resources to be shared with the GuC.  At this point,
 * we require just one object that can be mapped through the GGTT.
 */
int i915_guc_submission_init(struct drm_i915_private *dev_priv)
{
        struct intel_guc *guc = &dev_priv->guc;
        struct i915_vma *vma;
        u32 size;

        /* Wipe bitmap & delete client in case of reinitialisation */
        bitmap_clear(guc->doorbell_bitmap, 0, GUC_MAX_DOORBELLS);
        i915_guc_submission_disable(dev_priv);

        if (!i915.enable_guc_submission)
                return 0; /* not enabled  */

        if (guc->ctx_pool_vma)
                return 0; /* already allocated */

        size = PAGE_ALIGN(GUC_MAX_GPU_CONTEXTS*sizeof(struct guc_context_desc));
        vma = guc_allocate_vma(guc, size);
        if (IS_ERR(vma))
                return PTR_ERR(vma);

        guc->ctx_pool_vma = vma;
        ida_init(&guc->ctx_ids);
        guc_create_log(guc);
        guc_create_ads(guc);

        return 0;
}

int i915_guc_submission_enable(struct drm_i915_private *dev_priv)
{
        struct intel_guc *guc = &dev_priv->guc;
        struct i915_guc_client *client;
        struct intel_engine_cs *engine;

        /* client for execbuf submission */
        client = guc_client_alloc(dev_priv,
                                  INTEL_INFO(dev_priv)->ring_mask,
                                  GUC_CTX_PRIORITY_KMD_NORMAL,
                                  dev_priv->kernel_context);
        if (!client) {
                DRM_ERROR("Failed to create execbuf guc_client\n");
                return -ENOMEM;
        }

        guc->execbuf_client = client;
        host2guc_sample_forcewake(guc, client);
        guc_init_doorbell_hw(guc);

        /* Take over from manual control of ELSP (execlists) */
        for_each_engine(engine, dev_priv)
                engine->submit_request = i915_guc_submit;

        return 0;
}

void i915_guc_submission_disable(struct drm_i915_private *dev_priv)
{
        struct intel_guc *guc = &dev_priv->guc;

        if (!guc->execbuf_client)
                return;

        /* Revert back to manual ELSP submission */
        intel_execlists_enable_submission(dev_priv);

        guc_client_free(dev_priv, guc->execbuf_client);
        guc->execbuf_client = NULL;
}

void i915_guc_submission_fini(struct drm_i915_private *dev_priv)
{
        struct intel_guc *guc = &dev_priv->guc;

        guc_release_vma(fetch_and_zero(&guc->ads_vma));
        guc_release_vma(fetch_and_zero(&guc->log_vma));

        if (guc->ctx_pool_vma)
                ida_destroy(&guc->ctx_ids);
        guc_release_vma(fetch_and_zero(&guc->ctx_pool_vma));
}

/**
 * intel_guc_suspend() - notify GuC entering suspend state
 * @dev:        drm device
 */
int intel_guc_suspend(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = to_i915(dev);
        struct intel_guc *guc = &dev_priv->guc;
        struct i915_gem_context *ctx;
        u32 data[3];

        if (guc->guc_fw.guc_fw_load_status != GUC_FIRMWARE_SUCCESS)
                return 0;

        ctx = dev_priv->kernel_context;

        data[0] = HOST2GUC_ACTION_ENTER_S_STATE;
        /* any value greater than GUC_POWER_D0 */
        data[1] = GUC_POWER_D1;
        /* first page is shared data with GuC */
        data[2] = i915_gem_obj_ggtt_offset(ctx->engine[RCS].state);

        return host2guc_action(guc, data, ARRAY_SIZE(data));
}


/**
 * intel_guc_resume() - notify GuC resuming from suspend state
 * @dev:        drm device
 */
int intel_guc_resume(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = to_i915(dev);
        struct intel_guc *guc = &dev_priv->guc;
        struct i915_gem_context *ctx;
        u32 data[3];

        if (guc->guc_fw.guc_fw_load_status != GUC_FIRMWARE_SUCCESS)
                return 0;

        ctx = dev_priv->kernel_context;

        data[0] = HOST2GUC_ACTION_EXIT_S_STATE;
        data[1] = GUC_POWER_D0;
        /* first page is shared data with GuC */
        data[2] = i915_gem_obj_ggtt_offset(ctx->engine[RCS].state);

        return host2guc_action(guc, data, ARRAY_SIZE(data));
}