// SPDX-License-Identifier: GPL-2.0-only
/*
 * Tegra host1x Command DMA
 *
 * Copyright (c) 2010-2013, NVIDIA Corporation.
 */


#include <asm/cacheflush.h>
#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <linux/host1x.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/kfifo.h>
#include <linux/slab.h>
#include <trace/events/host1x.h>

#include "cdma.h"
#include "channel.h"
#include "dev.h"
#include "debug.h"
#include "job.h"

/*
 * push_buffer
 *
 * The push buffer is a circular array of words to be fetched by command DMA.
 * Note that it works slightly differently to the sync queue; fence == pos
 * means that the push buffer is full, not empty.
 */

/*
 * Typically the commands written into the push buffer are a pair of words. We
 * use slots to represent each of these pairs and to simplify things. Note the
 * strange number of slots allocated here. 512 slots will fit exactly within a
 * single memory page. We also need one additional word at the end of the push
 * buffer for the RESTART opcode that will instruct the CDMA to jump back to
 * the beginning of the push buffer. With 512 slots, this means that we'll use
 * 2 memory pages and waste 4092 bytes of the second page that will never be
 * used.
 */
#define HOST1X_PUSHBUFFER_SLOTS 511

/*
 * Clean up push buffer resources
 */
static void host1x_pushbuffer_destroy(struct push_buffer *pb)
{
        struct host1x_cdma *cdma = pb_to_cdma(pb);
        struct host1x *host1x = cdma_to_host1x(cdma);

        if (!pb->mapped)
                return;

        if (host1x->domain) {
                iommu_unmap(host1x->domain, pb->dma, pb->alloc_size);
                free_iova(&host1x->iova, iova_pfn(&host1x->iova, pb->dma));
        }

        dma_free_wc(host1x->dev, pb->alloc_size, pb->mapped, pb->phys);

        pb->mapped = NULL;
        pb->phys = 0;
}

/*
 * Init push buffer resources
 */
static int host1x_pushbuffer_init(struct push_buffer *pb)
{
        struct host1x_cdma *cdma = pb_to_cdma(pb);
        struct host1x *host1x = cdma_to_host1x(cdma);
        struct iova *alloc;
        u32 size;
        int err;

        pb->mapped = NULL;
        pb->phys = 0;
        pb->size = HOST1X_PUSHBUFFER_SLOTS * 8;

        size = pb->size + 4;

        /* initialize buffer pointers */
        pb->fence = pb->size - 8;
        pb->pos = 0;

        if (host1x->domain) {
                unsigned long shift;

                size = iova_align(&host1x->iova, size);

                pb->mapped = dma_alloc_wc(host1x->dev, size, &pb->phys,
                                          GFP_KERNEL);
                if (!pb->mapped)
                        return -ENOMEM;

                shift = iova_shift(&host1x->iova);
                alloc = alloc_iova(&host1x->iova, size >> shift,
                                   host1x->iova_end >> shift, true);
                if (!alloc) {
                        err = -ENOMEM;
                        goto iommu_free_mem;
                }

                pb->dma = iova_dma_addr(&host1x->iova, alloc);
                err = iommu_map(host1x->domain, pb->dma, pb->phys, size,
                                IOMMU_READ);
                if (err)
                        goto iommu_free_iova;
        } else {
                pb->mapped = dma_alloc_wc(host1x->dev, size, &pb->phys,
                                          GFP_KERNEL);
                if (!pb->mapped)
                        return -ENOMEM;

                pb->dma = pb->phys;
        }

        pb->alloc_size = size;

        host1x_hw_pushbuffer_init(host1x, pb);

        return 0;

iommu_free_iova:
        __free_iova(&host1x->iova, alloc);
iommu_free_mem:
        dma_free_wc(host1x->dev, size, pb->mapped, pb->phys);

        return err;
}

/*
 * Push two words to the push buffer
 * Caller must ensure push buffer is not full
 */
static void host1x_pushbuffer_push(struct push_buffer *pb, u32 op1, u32 op2)
{
        u32 *p = (u32 *)((void *)pb->mapped + pb->pos);

        WARN_ON(pb->pos == pb->fence);
        *(p++) = op1;
        *(p++) = op2;
        pb->pos += 8;

        if (pb->pos >= pb->size)
                pb->pos -= pb->size;
}

/*
 * Pop a number of two word slots from the push buffer
 * Caller must ensure push buffer is not empty
 */
static void host1x_pushbuffer_pop(struct push_buffer *pb, unsigned int slots)
{
        /* Advance the next write position */
        pb->fence += slots * 8;

        if (pb->fence >= pb->size)
                pb->fence -= pb->size;
}

/*
 * Return the number of two word slots free in the push buffer
 */
static u32 host1x_pushbuffer_space(struct push_buffer *pb)
{
        unsigned int fence = pb->fence;

        if (pb->fence < pb->pos)
                fence += pb->size;

        return (fence - pb->pos) / 8;
}

/*
 * Sleep (if necessary) until the requested event happens
 *   - CDMA_EVENT_SYNC_QUEUE_EMPTY : sync queue is completely empty.
 *     - Returns 1
 *   - CDMA_EVENT_PUSH_BUFFER_SPACE : there is space in the push buffer
 *     - Return the amount of space (> 0)
 * Must be called with the cdma lock held.
 */
unsigned int host1x_cdma_wait_locked(struct host1x_cdma *cdma,
                                     enum cdma_event event)
{
        for (;;) {
                struct push_buffer *pb = &cdma->push_buffer;
                unsigned int space;

                switch (event) {
                case CDMA_EVENT_SYNC_QUEUE_EMPTY:
                        space = list_empty(&cdma->sync_queue) ? 1 : 0;
                        break;

                case CDMA_EVENT_PUSH_BUFFER_SPACE:
                        space = host1x_pushbuffer_space(pb);
                        break;

                default:
                        WARN_ON(1);
                        return -EINVAL;
                }

                if (space)
                        return space;

                trace_host1x_wait_cdma(dev_name(cdma_to_channel(cdma)->dev),
                                       event);

                /* If somebody has managed to already start waiting, yield */
                if (cdma->event != CDMA_EVENT_NONE) {
                        mutex_unlock(&cdma->lock);
                        schedule();
                        mutex_lock(&cdma->lock);
                        continue;
                }

                cdma->event = event;

                mutex_unlock(&cdma->lock);
                wait_for_completion(&cdma->complete);
                mutex_lock(&cdma->lock);
        }

        return 0;
}

/*
 * Sleep (if necessary) until the push buffer has enough free space.
 *
 * Must be called with the cdma lock held.
 */
static int host1x_cdma_wait_pushbuffer_space(struct host1x *host1x,
                                             struct host1x_cdma *cdma,
                                             unsigned int needed)
{
        while (true) {
                struct push_buffer *pb = &cdma->push_buffer;
                unsigned int space;

                space = host1x_pushbuffer_space(pb);
                if (space >= needed)
                        break;

                trace_host1x_wait_cdma(dev_name(cdma_to_channel(cdma)->dev),
                                       CDMA_EVENT_PUSH_BUFFER_SPACE);

                host1x_hw_cdma_flush(host1x, cdma);

                /* If somebody has managed to already start waiting, yield */
                if (cdma->event != CDMA_EVENT_NONE) {
                        mutex_unlock(&cdma->lock);
                        schedule();
                        mutex_lock(&cdma->lock);
                        continue;
                }

                cdma->event = CDMA_EVENT_PUSH_BUFFER_SPACE;

                mutex_unlock(&cdma->lock);
                wait_for_completion(&cdma->complete);
                mutex_lock(&cdma->lock);
        }

        return 0;
}
/*
 * Start timer that tracks the time spent by the job.
 * Must be called with the cdma lock held.
 */
static void cdma_start_timer_locked(struct host1x_cdma *cdma,
                                    struct host1x_job *job)
{
        if (cdma->timeout.client) {
                /* timer already started */
                return;
        }

        cdma->timeout.client = job->client;
        cdma->timeout.syncpt = job->syncpt;
        cdma->timeout.syncpt_val = job->syncpt_end;
        cdma->timeout.start_ktime = ktime_get();

        schedule_delayed_work(&cdma->timeout.wq,
                              msecs_to_jiffies(job->timeout));
}

/*
 * Stop timer when a buffer submission completes.
 * Must be called with the cdma lock held.
 */
static void stop_cdma_timer_locked(struct host1x_cdma *cdma)
{
        cancel_delayed_work(&cdma->timeout.wq);
        cdma->timeout.client = NULL;
}

/*
 * For all sync queue entries that have already finished according to the
 * current sync point registers:
 *  - unpin & unref their mems
 *  - pop their push buffer slots
 *  - remove them from the sync queue
 * This is normally called from the host code's worker thread, but can be
 * called manually if necessary.
 * Must be called with the cdma lock held.
 */
static void update_cdma_locked(struct host1x_cdma *cdma)
{
        bool signal = false;
        struct host1x_job *job, *n;

        /* If CDMA is stopped, queue is cleared and we can return */
        if (!cdma->running)
                return;

        /*
         * Walk the sync queue, reading the sync point registers as necessary,
         * to consume as many sync queue entries as possible without blocking
         */
        list_for_each_entry_safe(job, n, &cdma->sync_queue, list) {
                struct host1x_syncpt *sp = job->syncpt;

                /* Check whether this syncpt has completed, and bail if not */
                if (!host1x_syncpt_is_expired(sp, job->syncpt_end)) {
                        /* Start timer on next pending syncpt */
                        if (job->timeout)
                                cdma_start_timer_locked(cdma, job);

                        break;
                }

                /* Cancel timeout, when a buffer completes */
                if (cdma->timeout.client)
                        stop_cdma_timer_locked(cdma);

                /* Unpin the memory */
                host1x_job_unpin(job);

                /* Pop push buffer slots */
                if (job->num_slots) {
                        struct push_buffer *pb = &cdma->push_buffer;

                        host1x_pushbuffer_pop(pb, job->num_slots);

                        if (cdma->event == CDMA_EVENT_PUSH_BUFFER_SPACE)
                                signal = true;
                }

                list_del(&job->list);
                host1x_job_put(job);
        }

        if (cdma->event == CDMA_EVENT_SYNC_QUEUE_EMPTY &&
            list_empty(&cdma->sync_queue))
                signal = true;

        if (signal) {
                cdma->event = CDMA_EVENT_NONE;
                complete(&cdma->complete);
        }
}

void host1x_cdma_update_sync_queue(struct host1x_cdma *cdma,
                                   struct device *dev)
{
        struct host1x *host1x = cdma_to_host1x(cdma);
        u32 restart_addr, syncpt_incrs, syncpt_val;
        struct host1x_job *job, *next_job = NULL;

        syncpt_val = host1x_syncpt_load(cdma->timeout.syncpt);

        dev_dbg(dev, "%s: starting cleanup (thresh %d)\n",
                __func__, syncpt_val);

        /*
         * Move the sync_queue read pointer to the first entry that hasn't
         * completed based on the current HW syncpt value. It's likely there
         * won't be any (i.e. we're still at the head), but covers the case
         * where a syncpt incr happens just prior/during the teardown.
         */

        dev_dbg(dev, "%s: skip completed buffers still in sync_queue\n",
                __func__);

        list_for_each_entry(job, &cdma->sync_queue, list) {
                if (syncpt_val < job->syncpt_end) {

                        if (!list_is_last(&job->list, &cdma->sync_queue))
                                next_job = list_next_entry(job, list);

                        goto syncpt_incr;
                }

                host1x_job_dump(dev, job);
        }

        /* all jobs have been completed */
        job = NULL;

syncpt_incr:

        /*
         * Increment with CPU the remaining syncpts of a partially executed job.
         *
         * CDMA will continue execution starting with the next job or will get
         * into idle state.
         */
        if (next_job)
                restart_addr = next_job->first_get;
        else
                restart_addr = cdma->last_pos;

        /* do CPU increments for the remaining syncpts */
        if (job) {
                dev_dbg(dev, "%s: perform CPU incr on pending buffers\n",
                        __func__);

                /* won't need a timeout when replayed */
                job->timeout = 0;

                syncpt_incrs = job->syncpt_end - syncpt_val;
                dev_dbg(dev, "%s: CPU incr (%d)\n", __func__, syncpt_incrs);

                host1x_job_dump(dev, job);

                /* safe to use CPU to incr syncpts */
                host1x_hw_cdma_timeout_cpu_incr(host1x, cdma, job->first_get,
                                                syncpt_incrs, job->syncpt_end,
                                                job->num_slots);

                dev_dbg(dev, "%s: finished sync_queue modification\n",
                        __func__);
        }

        /* roll back DMAGET and start up channel again */
        host1x_hw_cdma_resume(host1x, cdma, restart_addr);
}

/*
 * Create a cdma
 */
int host1x_cdma_init(struct host1x_cdma *cdma)
{
        int err;

        mutex_init(&cdma->lock);
        init_completion(&cdma->complete);

        INIT_LIST_HEAD(&cdma->sync_queue);

        cdma->event = CDMA_EVENT_NONE;
        cdma->running = false;
        cdma->torndown = false;

        err = host1x_pushbuffer_init(&cdma->push_buffer);
        if (err)
                return err;

        return 0;
}

/*
 * Destroy a cdma
 */
int host1x_cdma_deinit(struct host1x_cdma *cdma)
{
        struct push_buffer *pb = &cdma->push_buffer;
        struct host1x *host1x = cdma_to_host1x(cdma);

        if (cdma->running) {
                pr_warn("%s: CDMA still running\n", __func__);
                return -EBUSY;
        }

        host1x_pushbuffer_destroy(pb);
        host1x_hw_cdma_timeout_destroy(host1x, cdma);

        return 0;
}

/*
 * Begin a cdma submit
 */
int host1x_cdma_begin(struct host1x_cdma *cdma, struct host1x_job *job)
{
        struct host1x *host1x = cdma_to_host1x(cdma);

        mutex_lock(&cdma->lock);

        if (job->timeout) {
                /* init state on first submit with timeout value */
                if (!cdma->timeout.initialized) {
                        int err;

                        err = host1x_hw_cdma_timeout_init(host1x, cdma);
                        if (err) {
                                mutex_unlock(&cdma->lock);
                                return err;
                        }
                }
        }

        if (!cdma->running)
                host1x_hw_cdma_start(host1x, cdma);

        cdma->slots_free = 0;
        cdma->slots_used = 0;
        cdma->first_get = cdma->push_buffer.pos;

        trace_host1x_cdma_begin(dev_name(job->channel->dev));
        return 0;
}

/*
 * Push two words into a push buffer slot
 * Blocks as necessary if the push buffer is full.
 */
void host1x_cdma_push(struct host1x_cdma *cdma, u32 op1, u32 op2)
{
        struct host1x *host1x = cdma_to_host1x(cdma);
        struct push_buffer *pb = &cdma->push_buffer;
        u32 slots_free = cdma->slots_free;

        if (host1x_debug_trace_cmdbuf)
                trace_host1x_cdma_push(dev_name(cdma_to_channel(cdma)->dev),
                                       op1, op2);

        if (slots_free == 0) {
                host1x_hw_cdma_flush(host1x, cdma);
                slots_free = host1x_cdma_wait_locked(cdma,
                                                CDMA_EVENT_PUSH_BUFFER_SPACE);
        }

        cdma->slots_free = slots_free - 1;
        cdma->slots_used++;
        host1x_pushbuffer_push(pb, op1, op2);
}

/*
 * Push four words into two consecutive push buffer slots. Note that extra
 * care needs to be taken not to split the two slots across the end of the
 * push buffer. Otherwise the RESTART opcode at the end of the push buffer
 * that ensures processing will restart at the beginning will break up the
 * four words.
 *
 * Blocks as necessary if the push buffer is full.
 */
void host1x_cdma_push_wide(struct host1x_cdma *cdma, u32 op1, u32 op2,
                           u32 op3, u32 op4)
{
        struct host1x_channel *channel = cdma_to_channel(cdma);
        struct host1x *host1x = cdma_to_host1x(cdma);
        struct push_buffer *pb = &cdma->push_buffer;
        unsigned int needed = 2, extra = 0, i;
        unsigned int space = cdma->slots_free;

        if (host1x_debug_trace_cmdbuf)
                trace_host1x_cdma_push_wide(dev_name(channel->dev), op1, op2,
                                            op3, op4);

        /* compute number of extra slots needed for padding */
        if (pb->pos + 16 > pb->size) {
                extra = (pb->size - pb->pos) / 8;
                needed += extra;
        }

        host1x_cdma_wait_pushbuffer_space(host1x, cdma, needed);
        space = host1x_pushbuffer_space(pb);

        cdma->slots_free = space - needed;
        cdma->slots_used += needed;

        /*
         * Note that we rely on the fact that this is only used to submit wide
         * gather opcodes, which consist of 3 words, and they are padded with
         * a NOP to avoid having to deal with fractional slots (a slot always
         * represents 2 words). The fourth opcode passed to this function will
         * therefore always be a NOP.
         *
         * This works around a slight ambiguity when it comes to opcodes. For
         * all current host1x incarnations the NOP opcode uses the exact same
         * encoding (0x20000000), so we could hard-code the value here, but a
         * new incarnation may change it and break that assumption.
         */
        for (i = 0; i < extra; i++)
                host1x_pushbuffer_push(pb, op4, op4);

        host1x_pushbuffer_push(pb, op1, op2);
        host1x_pushbuffer_push(pb, op3, op4);
}

/*
 * End a cdma submit
 * Kick off DMA, add job to the sync queue, and a number of slots to be freed
 * from the pushbuffer. The handles for a submit must all be pinned at the same
 * time, but they can be unpinned in smaller chunks.
 */
void host1x_cdma_end(struct host1x_cdma *cdma,
                     struct host1x_job *job)
{
        struct host1x *host1x = cdma_to_host1x(cdma);
        bool idle = list_empty(&cdma->sync_queue);

        host1x_hw_cdma_flush(host1x, cdma);

        job->first_get = cdma->first_get;
        job->num_slots = cdma->slots_used;
        host1x_job_get(job);
        list_add_tail(&job->list, &cdma->sync_queue);

        /* start timer on idle -> active transitions */
        if (job->timeout && idle)
                cdma_start_timer_locked(cdma, job);

        trace_host1x_cdma_end(dev_name(job->channel->dev));
        mutex_unlock(&cdma->lock);
}

/*
 * Update cdma state according to current sync point values
 */
void host1x_cdma_update(struct host1x_cdma *cdma)
{
        mutex_lock(&cdma->lock);
        update_cdma_locked(cdma);
        mutex_unlock(&cdma->lock);
}