drivers/dma/virt-dma.h

   1 /*
   2  * Virtual DMA channel support for DMAengine
   3  *
   4  * Copyright (C) 2012 Russell King
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10 #ifndef VIRT_DMA_H
  11 #define VIRT_DMA_H
  12
  13 #include <linux/dmaengine.h>
  14 #include <linux/interrupt.h>
  15
  16 #include "dmaengine.h"
  17
  18 struct virt_dma_desc {
  19         struct dma_async_tx_descriptor tx;
  20         /* protected by vc.lock */
  21         struct list_head node;
  22 };
  23
  24 struct virt_dma_chan {
  25         struct dma_chan chan;
  26         struct tasklet_struct task;
  27         void (*desc_free)(struct virt_dma_desc *);
  28
  29         spinlock_t lock;
  30
  31         /* protected by vc.lock */
  32         struct list_head desc_submitted;
  33         struct list_head desc_issued;
  34         struct list_head desc_completed;
  35 };
  36
  37 static inline struct virt_dma_chan *to_virt_chan(struct dma_chan *chan)
  38 {
  39         return container_of(chan, struct virt_dma_chan, chan);
  40 }
  41
  42 void vchan_dma_desc_free_list(struct virt_dma_chan *vc, struct list_head *head);
  43
  44 void vchan_init(struct virt_dma_chan *vc, struct dma_device *dmadev);
  45
  46 /**
  47  * vchan_tx_prep - prepare a descriptor
  48  * vc: virtual channel allocating this descriptor
  49  * vd: virtual descriptor to prepare
  50  * tx_flags: flags argument passed in to prepare function
  51  */
  52 static inline struct dma_async_tx_descriptor *vchan_tx_prep(struct virt_dma_chan *vc,
  53         struct virt_dma_desc *vd, unsigned long tx_flags)
  54 {
  55         extern dma_cookie_t vchan_tx_submit(struct dma_async_tx_descriptor *);
  56
  57         dma_async_tx_descriptor_init(&vd->tx, &vc->chan);
  58         vd->tx.flags = tx_flags;
  59         vd->tx.tx_submit = vchan_tx_submit;
  60
  61         return &vd->tx;
  62 }
  63
  64 /**
  65  * vchan_issue_pending - move submitted descriptors to issued list
  66  * vc: virtual channel to update
  67  *
  68  * vc.lock must be held by caller
  69  */
  70 static inline bool vchan_issue_pending(struct virt_dma_chan *vc)
  71 {
  72         list_splice_tail_init(&vc->desc_submitted, &vc->desc_issued);
  73         return !list_empty(&vc->desc_issued);
  74 }
  75
  76 /**
  77  * vchan_cookie_complete - report completion of a descriptor
  78  * vd: virtual descriptor to update
  79  *
  80  * vc.lock must be held by caller
  81  */
  82 static inline void vchan_cookie_complete(struct virt_dma_desc *vd)
  83 {
  84         struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
  85
  86         dma_cookie_complete(&vd->tx);
  87         dev_vdbg(vc->chan.device->dev, "txd %p[%x]: marked complete\n",
  88                 vd, vd->tx.cookie);
  89         list_add_tail(&vd->node, &vc->desc_completed);
  90
  91         tasklet_schedule(&vc->task);
  92 }
  93
  94 /**
  95  * vchan_next_desc - peek at the next descriptor to be processed
  96  * vc: virtual channel to obtain descriptor from
  97  *
  98  * vc.lock must be held by caller
  99  */
 100 static inline struct virt_dma_desc *vchan_next_desc(struct virt_dma_chan *vc)
 101 {
 102         if (list_empty(&vc->desc_issued))
 103                 return NULL;
 104
 105         return list_first_entry(&vc->desc_issued, struct virt_dma_desc, node);
 106 }
 107
 108 /**
 109  * vchan_get_all_descriptors - obtain all submitted and issued descriptors
 110  * vc: virtual channel to get descriptors from
 111  * head: list of descriptors found
 112  *
 113  * vc.lock must be held by caller
 114  *
 115  * Removes all submitted and issued descriptors from internal lists, and
 116  * provides a list of all descriptors found
 117  */
 118 static inline void vchan_get_all_descriptors(struct virt_dma_chan *vc,
 119         struct list_head *head)
 120 {
 121         list_splice_tail_init(&vc->desc_submitted, head);
 122         list_splice_tail_init(&vc->desc_issued, head);
 123         list_splice_tail_init(&vc->desc_completed, head);
 124 }
 125
 126 static inline void vchan_free_chan_resources(struct virt_dma_chan *vc)
 127 {
 128         unsigned long flags;
 129         LIST_HEAD(head);
 130
 131         spin_lock_irqsave(&vc->lock, flags);
 132         vchan_get_all_descriptors(vc, &head);
 133         spin_unlock_irqrestore(&vc->lock, flags);
 134
 135         vchan_dma_desc_free_list(vc, &head);
 136 }
 137
 138 #endif