155 lines
3.9 KiB
C
155 lines
3.9 KiB
C
/*
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* Virtual DMA channel support for DMAengine
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*
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* Copyright (C) 2012 Russell King
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#ifndef VIRT_DMA_H
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#define VIRT_DMA_H
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#include <linux/dmaengine.h>
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#include <linux/interrupt.h>
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#include "dmaengine.h"
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struct virt_dma_desc {
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struct dma_async_tx_descriptor tx;
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/* protected by vc.lock */
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struct list_head node;
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};
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struct virt_dma_chan {
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struct dma_chan chan;
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struct tasklet_struct task;
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void (*desc_free)(struct virt_dma_desc *);
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spinlock_t lock;
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/* protected by vc.lock */
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struct list_head desc_submitted;
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struct list_head desc_issued;
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struct list_head desc_completed;
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struct virt_dma_desc *cyclic;
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};
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static inline struct virt_dma_chan *to_virt_chan(struct dma_chan *chan)
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{
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return container_of(chan, struct virt_dma_chan, chan);
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}
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void vchan_dma_desc_free_list(struct virt_dma_chan *vc, struct list_head *head);
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void vchan_init(struct virt_dma_chan *vc, struct dma_device *dmadev);
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struct virt_dma_desc *vchan_find_desc(struct virt_dma_chan *, dma_cookie_t);
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/**
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* vchan_tx_prep - prepare a descriptor
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* vc: virtual channel allocating this descriptor
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* vd: virtual descriptor to prepare
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* tx_flags: flags argument passed in to prepare function
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*/
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static inline struct dma_async_tx_descriptor *vchan_tx_prep(struct virt_dma_chan *vc,
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struct virt_dma_desc *vd, unsigned long tx_flags)
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{
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extern dma_cookie_t vchan_tx_submit(struct dma_async_tx_descriptor *);
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dma_async_tx_descriptor_init(&vd->tx, &vc->chan);
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vd->tx.flags = tx_flags;
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vd->tx.tx_submit = vchan_tx_submit;
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return &vd->tx;
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}
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/**
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* vchan_issue_pending - move submitted descriptors to issued list
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* vc: virtual channel to update
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*
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* vc.lock must be held by caller
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*/
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static inline bool vchan_issue_pending(struct virt_dma_chan *vc)
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{
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list_splice_tail_init(&vc->desc_submitted, &vc->desc_issued);
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return !list_empty(&vc->desc_issued);
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}
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/**
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* vchan_cookie_complete - report completion of a descriptor
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* vd: virtual descriptor to update
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*
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* vc.lock must be held by caller
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*/
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static inline void vchan_cookie_complete(struct virt_dma_desc *vd)
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{
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struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
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dma_cookie_t cookie;
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cookie = vd->tx.cookie;
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dma_cookie_complete(&vd->tx);
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dev_vdbg(vc->chan.device->dev, "txd %p[%x]: marked complete\n",
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vd, cookie);
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list_add_tail(&vd->node, &vc->desc_completed);
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tasklet_schedule(&vc->task);
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}
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/**
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* vchan_cyclic_callback - report the completion of a period
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* vd: virtual descriptor
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*/
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static inline void vchan_cyclic_callback(struct virt_dma_desc *vd)
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{
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struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
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vc->cyclic = vd;
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tasklet_schedule(&vc->task);
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}
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/**
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* vchan_next_desc - peek at the next descriptor to be processed
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* vc: virtual channel to obtain descriptor from
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*
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* vc.lock must be held by caller
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*/
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static inline struct virt_dma_desc *vchan_next_desc(struct virt_dma_chan *vc)
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{
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if (list_empty(&vc->desc_issued))
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return NULL;
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return list_first_entry(&vc->desc_issued, struct virt_dma_desc, node);
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}
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/**
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* vchan_get_all_descriptors - obtain all submitted and issued descriptors
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* vc: virtual channel to get descriptors from
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* head: list of descriptors found
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*
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* vc.lock must be held by caller
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*
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* Removes all submitted and issued descriptors from internal lists, and
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* provides a list of all descriptors found
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*/
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static inline void vchan_get_all_descriptors(struct virt_dma_chan *vc,
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struct list_head *head)
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{
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list_splice_tail_init(&vc->desc_submitted, head);
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list_splice_tail_init(&vc->desc_issued, head);
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list_splice_tail_init(&vc->desc_completed, head);
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}
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static inline void vchan_free_chan_resources(struct virt_dma_chan *vc)
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{
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unsigned long flags;
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LIST_HEAD(head);
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spin_lock_irqsave(&vc->lock, flags);
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vchan_get_all_descriptors(vc, &head);
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spin_unlock_irqrestore(&vc->lock, flags);
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vchan_dma_desc_free_list(vc, &head);
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}
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#endif
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