// SPDX-License-Identifier: GPL-2.0-only
/*
 * Virtual DMA channel support for DMAengine
 *
 * Copyright (C) 2012 Russell King
 */
#include <linux/device.h>
#include <linux/dmaengine.h>
#include <linux/module.h>
#include <linux/spinlock.h>

#include "virt-dma.h"

static struct virt_dma_desc *to_virt_desc(struct dma_async_tx_descriptor *tx)
{
        return container_of(tx, struct virt_dma_desc, tx);
}

dma_cookie_t vchan_tx_submit(struct dma_async_tx_descriptor *tx)
{
        struct virt_dma_chan *vc = to_virt_chan(tx->chan);
        struct virt_dma_desc *vd = to_virt_desc(tx);
        unsigned long flags;
        dma_cookie_t cookie;

        spin_lock_irqsave(&vc->lock, flags);
        cookie = dma_cookie_assign(tx);

        list_move_tail(&vd->node, &vc->desc_submitted);
        spin_unlock_irqrestore(&vc->lock, flags);

        dev_dbg(vc->chan.device->dev, "vchan %p: txd %p[%x]: submitted\n",
                vc, vd, cookie);

        return cookie;
}
EXPORT_SYMBOL_GPL(vchan_tx_submit);

/**
 * vchan_tx_desc_free - free a reusable descriptor
 * @tx: the transfer
 *
 * This function frees a previously allocated reusable descriptor. The only
 * other way is to clear the DMA_CTRL_REUSE flag and submit one last time the
 * transfer.
 *
 * Returns 0 upon success
 */
int vchan_tx_desc_free(struct dma_async_tx_descriptor *tx)
{
        struct virt_dma_chan *vc = to_virt_chan(tx->chan);
        struct virt_dma_desc *vd = to_virt_desc(tx);
        unsigned long flags;

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

        dev_dbg(vc->chan.device->dev, "vchan %p: txd %p[%x]: freeing\n",
                vc, vd, vd->tx.cookie);
        vc->desc_free(vd);
        return 0;
}
EXPORT_SYMBOL_GPL(vchan_tx_desc_free);

struct virt_dma_desc *vchan_find_desc(struct virt_dma_chan *vc,
        dma_cookie_t cookie)
{
        struct virt_dma_desc *vd;

        list_for_each_entry(vd, &vc->desc_issued, node)
                if (vd->tx.cookie == cookie)
                        return vd;

        return NULL;
}
EXPORT_SYMBOL_GPL(vchan_find_desc);

/*
 * This tasklet handles the completion of a DMA descriptor by
 * calling its callback and freeing it.
 */
static void vchan_complete(struct tasklet_struct *t)
{
        struct virt_dma_chan *vc = from_tasklet(vc, t, task);
        struct virt_dma_desc *vd, *_vd;
        struct dmaengine_desc_callback cb;
        LIST_HEAD(head);

        spin_lock_irq(&vc->lock);
        list_splice_tail_init(&vc->desc_completed, &head);
        vd = vc->cyclic;
        if (vd) {
                vc->cyclic = NULL;
                dmaengine_desc_get_callback(&vd->tx, &cb);
        } else {
                memset(&cb, 0, sizeof(cb));
        }
        spin_unlock_irq(&vc->lock);

        dmaengine_desc_callback_invoke(&cb, &vd->tx_result);

        list_for_each_entry_safe(vd, _vd, &head, node) {
                dmaengine_desc_get_callback(&vd->tx, &cb);

                list_del(&vd->node);
                dmaengine_desc_callback_invoke(&cb, &vd->tx_result);
                vchan_vdesc_fini(vd);
        }
}

void vchan_dma_desc_free_list(struct virt_dma_chan *vc, struct list_head *head)
{
        struct virt_dma_desc *vd, *_vd;

        list_for_each_entry_safe(vd, _vd, head, node) {
                list_del(&vd->node);
                vchan_vdesc_fini(vd);
        }
}
EXPORT_SYMBOL_GPL(vchan_dma_desc_free_list);

void vchan_init(struct virt_dma_chan *vc, struct dma_device *dmadev)
{
        dma_cookie_init(&vc->chan);

        spin_lock_init(&vc->lock);
        INIT_LIST_HEAD(&vc->desc_allocated);
        INIT_LIST_HEAD(&vc->desc_submitted);
        INIT_LIST_HEAD(&vc->desc_issued);
        INIT_LIST_HEAD(&vc->desc_completed);
        INIT_LIST_HEAD(&vc->desc_terminated);

        tasklet_setup(&vc->task, vchan_complete);

        vc->chan.device = dmadev;
        list_add_tail(&vc->chan.device_node, &dmadev->channels);
}
EXPORT_SYMBOL_GPL(vchan_init);

MODULE_AUTHOR("Russell King");
MODULE_DESCRIPTION("Virtual DMA channel support for DMAengine");
MODULE_LICENSE("GPL");