virt-dma.h

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/*
 * Virtual DMA channel support for DMAengine
 *
 * Copyright (C) 2012 Russell King
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#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;
    /* 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_submitted;
    struct list_head desc_issued;
    struct list_head desc_completed;

    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);

static inline struct dma_async_tx_descriptor *vchan_tx_prep(struct virt_dma_chan *vc,
    struct virt_dma_desc *vd, unsigned long tx_flags)
{
    extern dma_cookie_t vchan_tx_submit(struct dma_async_tx_descriptor *);

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

    return &vd->tx;
}

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);
}

static inline void vchan_cookie_complete(struct virt_dma_desc *vd)
{
    struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);

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

    tasklet_schedule(&vc->task);
}

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);
}

static inline struct virt_dma_desc *vchan_next_desc(struct virt_dma_chan *vc)
{
    if (list_empty(&vc->desc_issued))
        return NULL;

    return list_first_entry(&vc->desc_issued, struct virt_dma_desc, node);
}

static inline void vchan_get_all_descriptors(struct virt_dma_chan *vc,
    struct list_head *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);
}

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

    spin_lock_irqsave(&vc->lock, flags);
    vchan_get_all_descriptors(vc, &head);
    spin_unlock_irqrestore(&vc->lock, flags);

    vchan_dma_desc_free_list(vc, &head);
}

#endif