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_allocated;
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);
/**
* 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)
{
extern dma_cookie_t vchan_tx_submit(struct dma_async_tx_descriptor *);
extern int vchan_tx_desc_free(struct dma_async_tx_descriptor *);
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;
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_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_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)
{
if (list_empty(&vc->desc_issued))
return NULL;
return list_first_entry(&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);
}
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.
*/
static inline void vchan_synchronize(struct virt_dma_chan *vc)
{
tasklet_kill(&vc->task);
}
#endif