/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * Virtual DMA channel support for DMAengine
 *
 * Copyright (C) 2012 Russell King
 */
#ifndef VIRT_DMA_H
#define VIRT_DMA_H

#include <linux/dmaengine.h>
#include <linux/interrupt.h>

#include "dmaengine.h"

struct virt_dma_desc {
        struct dma_async_tx_descriptor tx;
        struct dmaengine_result tx_result;
        /* protected by vc.lock */
        struct list_head node;
};

struct virt_dma_chan {
        struct dma_chan chan;
        struct tasklet_struct task;
        void (*desc_free)(struct virt_dma_desc *);

        spinlock_t lock;

        /* protected by vc.lock */
        struct list_head desc_allocated;
        struct list_head desc_submitted;
        struct list_head desc_issued;
        struct list_head desc_completed;
        struct list_head desc_terminated;

        struct virt_dma_desc *cyclic;
};

static inline struct virt_dma_chan *to_virt_chan(struct dma_chan *chan)
{
        return container_of(chan, struct virt_dma_chan, chan);
}

void vchan_dma_desc_free_list(struct virt_dma_chan *vc, struct list_head *head);
void vchan_init(struct virt_dma_chan *vc, struct dma_device *dmadev);
struct virt_dma_desc *vchan_find_desc(struct virt_dma_chan *, dma_cookie_t);
extern dma_cookie_t vchan_tx_submit(struct dma_async_tx_descriptor *);
extern int vchan_tx_desc_free(struct dma_async_tx_descriptor *);

/**
 * vchan_tx_prep - prepare a descriptor
 * @vc: virtual channel allocating this descriptor
 * @vd: virtual descriptor to prepare
 * @tx_flags: flags argument passed in to prepare function
 */
static inline struct dma_async_tx_descriptor *vchan_tx_prep(struct virt_dma_chan *vc,
        struct virt_dma_desc *vd, unsigned long tx_flags)
{
        unsigned long flags;

        dma_async_tx_descriptor_init(&vd->tx, &vc->chan);
        vd->tx.flags = tx_flags;
        vd->tx.tx_submit = vchan_tx_submit;
        vd->tx.desc_free = vchan_tx_desc_free;

        vd->tx_result.result = DMA_TRANS_NOERROR;
        vd->tx_result.residue = 0;

        spin_lock_irqsave(&vc->lock, flags);
        list_add_tail(&vd->node, &vc->desc_allocated);
        spin_unlock_irqrestore(&vc->lock, flags);

        return &vd->tx;
}

/**
 * vchan_issue_pending - move submitted descriptors to issued list
 * @vc: virtual channel to update
 *
 * vc.lock must be held by caller
 */
static inline bool vchan_issue_pending(struct virt_dma_chan *vc)
{
        list_splice_tail_init(&vc->desc_submitted, &vc->desc_issued);
        return !list_empty(&vc->desc_issued);
}

/**
 * vchan_cookie_complete - report completion of a descriptor
 * @vd: virtual descriptor to update
 *
 * vc.lock must be held by caller
 */
static inline void vchan_cookie_complete(struct virt_dma_desc *vd)
{
        struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
        dma_cookie_t cookie;

        cookie = vd->tx.cookie;
        dma_cookie_complete(&vd->tx);
        dev_vdbg(vc->chan.device->dev, "txd %p[%x]: marked complete\n",
                 vd, cookie);
        list_add_tail(&vd->node, &vc->desc_completed);

        tasklet_schedule(&vc->task);
}

/**
 * vchan_vdesc_fini - Free or reuse a descriptor
 * @vd: virtual descriptor to free/reuse
 */
static inline void vchan_vdesc_fini(struct virt_dma_desc *vd)
{
        struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);

        if (dmaengine_desc_test_reuse(&vd->tx)) {
                unsigned long flags;

                spin_lock_irqsave(&vc->lock, flags);
                list_add(&vd->node, &vc->desc_allocated);
                spin_unlock_irqrestore(&vc->lock, flags);
        } else {
                vc->desc_free(vd);
        }
}

/**
 * vchan_cyclic_callback - report the completion of a period
 * @vd: virtual descriptor
 */
static inline void vchan_cyclic_callback(struct virt_dma_desc *vd)
{
        struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);

        vc->cyclic = vd;
        tasklet_schedule(&vc->task);
}

/**
 * vchan_terminate_vdesc - Disable pending cyclic callback
 * @vd: virtual descriptor to be terminated
 *
 * vc.lock must be held by caller
 */
static inline void vchan_terminate_vdesc(struct virt_dma_desc *vd)
{
        struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);

        list_add_tail(&vd->node, &vc->desc_terminated);

        if (vc->cyclic == vd)
                vc->cyclic = NULL;
}

/**
 * vchan_next_desc - peek at the next descriptor to be processed
 * @vc: virtual channel to obtain descriptor from
 *
 * vc.lock must be held by caller
 */
static inline struct virt_dma_desc *vchan_next_desc(struct virt_dma_chan *vc)
{
        return list_first_entry_or_null(&vc->desc_issued,
                                        struct virt_dma_desc, node);
}

/**
 * vchan_get_all_descriptors - obtain all submitted and issued descriptors
 * @vc: virtual channel to get descriptors from
 * @head: list of descriptors found
 *
 * vc.lock must be held by caller
 *
 * Removes all submitted and issued descriptors from internal lists, and
 * provides a list of all descriptors found
 */
static inline void vchan_get_all_descriptors(struct virt_dma_chan *vc,
        struct list_head *head)
{
        list_splice_tail_init(&vc->desc_allocated, head);
        list_splice_tail_init(&vc->desc_submitted, head);
        list_splice_tail_init(&vc->desc_issued, head);
        list_splice_tail_init(&vc->desc_completed, head);
        list_splice_tail_init(&vc->desc_terminated, head);
}

static inline void vchan_free_chan_resources(struct virt_dma_chan *vc)
{
        struct virt_dma_desc *vd;
        unsigned long flags;
        LIST_HEAD(head);

        spin_lock_irqsave(&vc->lock, flags);
        vchan_get_all_descriptors(vc, &head);
        list_for_each_entry(vd, &head, node)
                dmaengine_desc_clear_reuse(&vd->tx);
        spin_unlock_irqrestore(&vc->lock, flags);

        vchan_dma_desc_free_list(vc, &head);
}

/**
 * vchan_synchronize() - synchronize callback execution to the current context
 * @vc: virtual channel to synchronize
 *
 * Makes sure that all scheduled or active callbacks have finished running. For
 * proper operation the caller has to ensure that no new callbacks are scheduled
 * after the invocation of this function started.
 * Free up the terminated cyclic descriptor to prevent memory leakage.
 */
static inline void vchan_synchronize(struct virt_dma_chan *vc)
{
        LIST_HEAD(head);
        unsigned long flags;

        tasklet_kill(&vc->task);

        spin_lock_irqsave(&vc->lock, flags);

        list_splice_tail_init(&vc->desc_terminated, &head);

        spin_unlock_irqrestore(&vc->lock, flags);

        vchan_dma_desc_free_list(vc, &head);
}

#endif