linux-imx

/*

 * 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.

 */

#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);