// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2018, The Linux Foundation. All rights reserved. */
/* Copyright (c) 2023 Collabora, Ltd. */
/* Copyright (c) 2024 Valve Corporation */

#include "msm_gem.h"
#include "a6xx_gpu.h"
#include "a6xx_gmu.xml.h"
#include "msm_mmu.h"
#include "msm_gpu_trace.h"

/*
 * Try to transition the preemption state from old to new. Return
 * true on success or false if the original state wasn't 'old'
 */
static inline bool try_preempt_state(struct a6xx_gpu *a6xx_gpu,
                enum a6xx_preempt_state old, enum a6xx_preempt_state new)
{
        enum a6xx_preempt_state cur = atomic_cmpxchg(&a6xx_gpu->preempt_state,
                old, new);

        return (cur == old);
}

/*
 * Force the preemption state to the specified state.  This is used in cases
 * where the current state is known and won't change
 */
static inline void set_preempt_state(struct a6xx_gpu *gpu,
                enum a6xx_preempt_state new)
{
        /*
         * preempt_state may be read by other cores trying to trigger a
         * preemption or in the interrupt handler so barriers are needed
         * before...
         */
        smp_mb__before_atomic();
        atomic_set(&gpu->preempt_state, new);
        /* ... and after*/
        smp_mb__after_atomic();
}

/* Write the most recent wptr for the given ring into the hardware */
static inline void update_wptr(struct a6xx_gpu *a6xx_gpu, struct msm_ringbuffer *ring)
{
        unsigned long flags;
        uint32_t wptr;

        spin_lock_irqsave(&ring->preempt_lock, flags);

        if (ring->restore_wptr) {
                wptr = get_wptr(ring);

                a6xx_fenced_write(a6xx_gpu, REG_A6XX_CP_RB_WPTR, wptr, BIT(0), false);

                ring->restore_wptr = false;
        }

        spin_unlock_irqrestore(&ring->preempt_lock, flags);
}

/* Return the highest priority ringbuffer with something in it */
static struct msm_ringbuffer *get_next_ring(struct msm_gpu *gpu)
{
        struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
        struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);

        unsigned long flags;
        int i;

        for (i = 0; i < gpu->nr_rings; i++) {
                bool empty;
                struct msm_ringbuffer *ring = gpu->rb[i];

                spin_lock_irqsave(&ring->preempt_lock, flags);
                empty = (get_wptr(ring) == gpu->funcs->get_rptr(gpu, ring));
                if (!empty && ring == a6xx_gpu->cur_ring)
                        empty = ring->memptrs->fence == a6xx_gpu->last_seqno[i];
                spin_unlock_irqrestore(&ring->preempt_lock, flags);

                if (!empty)
                        return ring;
        }

        return NULL;
}

static void a6xx_preempt_timer(struct timer_list *t)
{
        struct a6xx_gpu *a6xx_gpu = timer_container_of(a6xx_gpu, t,
                                                       preempt_timer);
        struct msm_gpu *gpu = &a6xx_gpu->base.base;
        struct drm_device *dev = gpu->dev;

        if (!try_preempt_state(a6xx_gpu, PREEMPT_TRIGGERED, PREEMPT_FAULTED))
                return;

        dev_err(dev->dev, "%s: preemption timed out\n", gpu->name);
        kthread_queue_work(gpu->worker, &gpu->recover_work);
}

static void preempt_prepare_postamble(struct a6xx_gpu *a6xx_gpu)
{
        u32 *postamble = a6xx_gpu->preempt_postamble_ptr;
        u32 count = 0;

        postamble[count++] = PKT7(CP_REG_RMW, 3);
        postamble[count++] = REG_A6XX_RBBM_PERFCTR_SRAM_INIT_CMD;
        postamble[count++] = 0;
        postamble[count++] = 1;

        postamble[count++] = PKT7(CP_WAIT_REG_MEM, 6);
        postamble[count++] = CP_WAIT_REG_MEM_0_FUNCTION(WRITE_EQ);
        postamble[count++] = CP_WAIT_REG_MEM_POLL_ADDR_LO(
                                REG_A6XX_RBBM_PERFCTR_SRAM_INIT_STATUS);
        postamble[count++] = CP_WAIT_REG_MEM_POLL_ADDR_HI(0);
        postamble[count++] = CP_WAIT_REG_MEM_3_REF(0x1);
        postamble[count++] = CP_WAIT_REG_MEM_4_MASK(0x1);
        postamble[count++] = CP_WAIT_REG_MEM_5_DELAY_LOOP_CYCLES(0);

        a6xx_gpu->preempt_postamble_len = count;

        a6xx_gpu->postamble_enabled = true;
}

static void preempt_disable_postamble(struct a6xx_gpu *a6xx_gpu)
{
        u32 *postamble = a6xx_gpu->preempt_postamble_ptr;

        /*
         * Disable the postamble by replacing the first packet header with a NOP
         * that covers the whole buffer.
         */
        *postamble = PKT7(CP_NOP, (a6xx_gpu->preempt_postamble_len - 1));

        a6xx_gpu->postamble_enabled = false;
}

/*
 * Set preemption keepalive vote. Please note that this vote is different from the one used in
 * a6xx_irq()
 */
static void a6xx_preempt_keepalive_vote(struct msm_gpu *gpu, bool on)
{
        struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
        struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);

        if (adreno_has_gmu_wrapper(adreno_gpu))
                return;

        gmu_write(&a6xx_gpu->gmu, REG_A6XX_GMU_PWR_COL_PREEMPT_KEEPALIVE, on);
}

void a6xx_preempt_irq(struct msm_gpu *gpu)
{
        uint32_t status;
        struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
        struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
        struct drm_device *dev = gpu->dev;

        if (!try_preempt_state(a6xx_gpu, PREEMPT_TRIGGERED, PREEMPT_PENDING))
                return;

        /* Delete the preemption watchdog timer */
        timer_delete(&a6xx_gpu->preempt_timer);

        /*
         * The hardware should be setting the stop bit of CP_CONTEXT_SWITCH_CNTL
         * to zero before firing the interrupt, but there is a non zero chance
         * of a hardware condition or a software race that could set it again
         * before we have a chance to finish. If that happens, log and go for
         * recovery
         */
        status = gpu_read(gpu, REG_A6XX_CP_CONTEXT_SWITCH_CNTL);
        if (unlikely(status & A6XX_CP_CONTEXT_SWITCH_CNTL_STOP)) {
                DRM_DEV_ERROR(&gpu->pdev->dev,
                                          "!!!!!!!!!!!!!!!! preemption faulted !!!!!!!!!!!!!! irq\n");
                set_preempt_state(a6xx_gpu, PREEMPT_FAULTED);
                dev_err(dev->dev, "%s: Preemption failed to complete\n",
                        gpu->name);
                kthread_queue_work(gpu->worker, &gpu->recover_work);
                return;
        }

        a6xx_gpu->cur_ring = a6xx_gpu->next_ring;
        a6xx_gpu->next_ring = NULL;

        set_preempt_state(a6xx_gpu, PREEMPT_FINISH);

        update_wptr(a6xx_gpu, a6xx_gpu->cur_ring);

        set_preempt_state(a6xx_gpu, PREEMPT_NONE);

        a6xx_preempt_keepalive_vote(gpu, false);

        trace_msm_gpu_preemption_irq(a6xx_gpu->cur_ring->id);

        /*
         * Retrigger preemption to avoid a deadlock that might occur when preemption
         * is skipped due to it being already in flight when requested.
         */
        a6xx_preempt_trigger(gpu);
}

void a6xx_preempt_hw_init(struct msm_gpu *gpu)
{
        struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
        struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
        int i;

        /* No preemption if we only have one ring */
        if (gpu->nr_rings == 1)
                return;

        for (i = 0; i < gpu->nr_rings; i++) {
                struct a6xx_preempt_record *record_ptr = a6xx_gpu->preempt[i];

                record_ptr->wptr = 0;
                record_ptr->rptr = 0;
                record_ptr->rptr_addr = shadowptr(a6xx_gpu, gpu->rb[i]);
                record_ptr->info = 0;
                record_ptr->data = 0;
                record_ptr->rbase = gpu->rb[i]->iova;
        }

        /* Write a 0 to signal that we aren't switching pagetables */
        gpu_write64(gpu, REG_A6XX_CP_CONTEXT_SWITCH_SMMU_INFO, 0);

        /* Enable the GMEM save/restore feature for preemption */
        gpu_write(gpu, REG_A6XX_RB_CONTEXT_SWITCH_GMEM_SAVE_RESTORE_ENABLE, 0x1);

        /* Reset the preemption state */
        set_preempt_state(a6xx_gpu, PREEMPT_NONE);

        spin_lock_init(&a6xx_gpu->eval_lock);

        /* Always come up on rb 0 */
        a6xx_gpu->cur_ring = gpu->rb[0];
}

void a6xx_preempt_trigger(struct msm_gpu *gpu)
{
        struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
        struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
        unsigned long flags;
        struct msm_ringbuffer *ring;
        unsigned int cntl;
        bool sysprof;

        if (gpu->nr_rings == 1)
                return;

        /*
         * Lock to make sure another thread attempting preemption doesn't skip it
         * while we are still evaluating the next ring. This makes sure the other
         * thread does start preemption if we abort it and avoids a soft lock.
         */
        spin_lock_irqsave(&a6xx_gpu->eval_lock, flags);

        /*
         * Try to start preemption by moving from NONE to START. If
         * unsuccessful, a preemption is already in flight
         */
        if (!try_preempt_state(a6xx_gpu, PREEMPT_NONE, PREEMPT_START)) {
                spin_unlock_irqrestore(&a6xx_gpu->eval_lock, flags);
                return;
        }

        cntl = A6XX_CP_CONTEXT_SWITCH_CNTL_LEVEL(a6xx_gpu->preempt_level);

        if (a6xx_gpu->skip_save_restore)
                cntl |= A6XX_CP_CONTEXT_SWITCH_CNTL_SKIP_SAVE_RESTORE;

        if (a6xx_gpu->uses_gmem)
                cntl |= A6XX_CP_CONTEXT_SWITCH_CNTL_USES_GMEM;

        cntl |= A6XX_CP_CONTEXT_SWITCH_CNTL_STOP;

        /* Get the next ring to preempt to */
        ring = get_next_ring(gpu);

        /*
         * If no ring is populated or the highest priority ring is the current
         * one do nothing except to update the wptr to the latest and greatest
         */
        if (!ring || (a6xx_gpu->cur_ring == ring)) {
                set_preempt_state(a6xx_gpu, PREEMPT_FINISH);
                update_wptr(a6xx_gpu, a6xx_gpu->cur_ring);
                set_preempt_state(a6xx_gpu, PREEMPT_NONE);
                spin_unlock_irqrestore(&a6xx_gpu->eval_lock, flags);
                return;
        }

        spin_unlock_irqrestore(&a6xx_gpu->eval_lock, flags);

        spin_lock_irqsave(&ring->preempt_lock, flags);

        struct a7xx_cp_smmu_info *smmu_info_ptr =
                a6xx_gpu->preempt_smmu[ring->id];
        struct a6xx_preempt_record *record_ptr = a6xx_gpu->preempt[ring->id];
        u64 ttbr0 = ring->memptrs->ttbr0;
        u32 context_idr = ring->memptrs->context_idr;

        smmu_info_ptr->ttbr0 = ttbr0;
        smmu_info_ptr->context_idr = context_idr;
        record_ptr->wptr = get_wptr(ring);

        /*
         * The GPU will write the wptr we set above when we preempt. Reset
         * restore_wptr to make sure that we don't write WPTR to the same
         * thing twice. It's still possible subsequent submissions will update
         * wptr again, in which case they will set the flag to true. This has
         * to be protected by the lock for setting the flag and updating wptr
         * to be atomic.
         */
        ring->restore_wptr = false;

        trace_msm_gpu_preemption_trigger(a6xx_gpu->cur_ring->id, ring->id);

        spin_unlock_irqrestore(&ring->preempt_lock, flags);

        /* Set the keepalive bit to keep the GPU ON until preemption is complete */
        a6xx_preempt_keepalive_vote(gpu, true);

        a6xx_fenced_write(a6xx_gpu,
                REG_A6XX_CP_CONTEXT_SWITCH_SMMU_INFO, a6xx_gpu->preempt_smmu_iova[ring->id],
                BIT(1), true);

        a6xx_fenced_write(a6xx_gpu,
                REG_A6XX_CP_CONTEXT_SWITCH_PRIV_NON_SECURE_RESTORE_ADDR,
                a6xx_gpu->preempt_iova[ring->id], BIT(1), true);

        a6xx_gpu->next_ring = ring;

        /* Start a timer to catch a stuck preemption */
        mod_timer(&a6xx_gpu->preempt_timer, jiffies + msecs_to_jiffies(10000));

        /* Enable or disable postamble as needed */
        sysprof = refcount_read(&a6xx_gpu->base.base.sysprof_active) > 1;

        if (!sysprof && !a6xx_gpu->postamble_enabled)
                preempt_prepare_postamble(a6xx_gpu);

        if (sysprof && a6xx_gpu->postamble_enabled)
                preempt_disable_postamble(a6xx_gpu);

        /* Set the preemption state to triggered */
        set_preempt_state(a6xx_gpu, PREEMPT_TRIGGERED);

        /* Trigger the preemption */
        a6xx_fenced_write(a6xx_gpu, REG_A6XX_CP_CONTEXT_SWITCH_CNTL, cntl, BIT(1), false);
}

static int preempt_init_ring(struct a6xx_gpu *a6xx_gpu,
                struct msm_ringbuffer *ring)
{
        struct adreno_gpu *adreno_gpu = &a6xx_gpu->base;
        struct msm_gpu *gpu = &adreno_gpu->base;
        struct drm_gem_object *bo = NULL;
        phys_addr_t ttbr;
        u64 iova = 0;
        void *ptr;
        int asid;

        ptr = msm_gem_kernel_new(gpu->dev,
                PREEMPT_RECORD_SIZE(adreno_gpu),
                MSM_BO_WC | MSM_BO_MAP_PRIV, gpu->vm, &bo, &iova);

        if (IS_ERR(ptr))
                return PTR_ERR(ptr);

        memset(ptr, 0, PREEMPT_RECORD_SIZE(adreno_gpu));

        msm_gem_object_set_name(bo, "preempt_record ring%d", ring->id);

        a6xx_gpu->preempt_bo[ring->id] = bo;
        a6xx_gpu->preempt_iova[ring->id] = iova;
        a6xx_gpu->preempt[ring->id] = ptr;

        struct a6xx_preempt_record *record_ptr = ptr;

        ptr = msm_gem_kernel_new(gpu->dev,
                PREEMPT_SMMU_INFO_SIZE,
                MSM_BO_WC | MSM_BO_MAP_PRIV | MSM_BO_GPU_READONLY,
                gpu->vm, &bo, &iova);

        if (IS_ERR(ptr))
                return PTR_ERR(ptr);

        memset(ptr, 0, PREEMPT_SMMU_INFO_SIZE);

        msm_gem_object_set_name(bo, "preempt_smmu_info ring%d", ring->id);

        a6xx_gpu->preempt_smmu_bo[ring->id] = bo;
        a6xx_gpu->preempt_smmu_iova[ring->id] = iova;
        a6xx_gpu->preempt_smmu[ring->id] = ptr;

        struct a7xx_cp_smmu_info *smmu_info_ptr = ptr;

        msm_iommu_pagetable_params(to_msm_vm(gpu->vm)->mmu, &ttbr, &asid);

        smmu_info_ptr->magic = GEN7_CP_SMMU_INFO_MAGIC;
        smmu_info_ptr->ttbr0 = ttbr;
        smmu_info_ptr->asid = 0xdecafbad;
        smmu_info_ptr->context_idr = 0;

        /* Set up the defaults on the preemption record */
        record_ptr->magic = A6XX_PREEMPT_RECORD_MAGIC;
        record_ptr->info = 0;
        record_ptr->data = 0;
        record_ptr->rptr = 0;
        record_ptr->wptr = 0;
        record_ptr->cntl = MSM_GPU_RB_CNTL_DEFAULT;
        record_ptr->rbase = ring->iova;
        record_ptr->counter = 0;
        record_ptr->bv_rptr_addr = rbmemptr(ring, bv_rptr);

        return 0;
}

void a6xx_preempt_fini(struct msm_gpu *gpu)
{
        struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
        struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
        int i;

        for (i = 0; i < gpu->nr_rings; i++)
                msm_gem_kernel_put(a6xx_gpu->preempt_bo[i], gpu->vm);
}

void a6xx_preempt_init(struct msm_gpu *gpu)
{
        struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
        struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
        int i;

        /* No preemption if we only have one ring */
        if (gpu->nr_rings <= 1)
                return;

        for (i = 0; i < gpu->nr_rings; i++) {
                if (preempt_init_ring(a6xx_gpu, gpu->rb[i]))
                        goto fail;
        }

        /* TODO: make this configurable? */
        a6xx_gpu->preempt_level = 1;
        a6xx_gpu->uses_gmem = 1;
        a6xx_gpu->skip_save_restore = 1;

        a6xx_gpu->preempt_postamble_ptr  = msm_gem_kernel_new(gpu->dev,
                        PAGE_SIZE,
                        MSM_BO_WC | MSM_BO_MAP_PRIV | MSM_BO_GPU_READONLY,
                        gpu->vm, &a6xx_gpu->preempt_postamble_bo,
                        &a6xx_gpu->preempt_postamble_iova);

        if (IS_ERR(a6xx_gpu->preempt_postamble_ptr))
                goto fail;

        preempt_prepare_postamble(a6xx_gpu);

        timer_setup(&a6xx_gpu->preempt_timer, a6xx_preempt_timer, 0);

        return;
fail:
        /*
         * On any failure our adventure is over. Clean up and
         * set nr_rings to 1 to force preemption off
         */
        a6xx_preempt_fini(gpu);
        gpu->nr_rings = 1;

        DRM_DEV_ERROR(&gpu->pdev->dev,
                                  "preemption init failed, disabling preemption\n");

        return;
}