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         struct virt_dma_desc *cyclic;
  37 };
  38
  39 static inline struct virt_dma_chan *to_virt_chan(struct dma_chan *chan)
  40 {
  41         return container_of(chan, struct virt_dma_chan, chan);
  42 }
  43
  44 void vchan_dma_desc_free_list(struct virt_dma_chan *vc, struct list_head *head);
  45 void vchan_init(struct virt_dma_chan *vc, struct dma_device *dmadev);
  46 struct virt_dma_desc *vchan_find_desc(struct virt_dma_chan *, dma_cookie_t);
  47
  48 /**
  49  * vchan_tx_prep - prepare a descriptor
  50  * vc: virtual channel allocating this descriptor
  51  * vd: virtual descriptor to prepare
  52  * tx_flags: flags argument passed in to prepare function
  53  */
  54 static inline struct dma_async_tx_descriptor *vchan_tx_prep(struct virt_dma_chan *vc,
  55         struct virt_dma_desc *vd, unsigned long tx_flags)
  56 {
  57         extern dma_cookie_t vchan_tx_submit(struct dma_async_tx_descriptor *);
  58
  59         dma_async_tx_descriptor_init(&vd->tx, &vc->chan);
  60         vd->tx.flags = tx_flags;
  61         vd->tx.tx_submit = vchan_tx_submit;
  62
  63         return &vd->tx;
  64 }
  65
  66 /**
  67  * vchan_issue_pending - move submitted descriptors to issued list
  68  * vc: virtual channel to update
  69  *
  70  * vc.lock must be held by caller
  71  */
  72 static inline bool vchan_issue_pending(struct virt_dma_chan *vc)
  73 {
  74         list_splice_tail_init(&vc->desc_submitted, &vc->desc_issued);
  75         return !list_empty(&vc->desc_issued);
  76 }
  77
  78 /**
  79  * vchan_cookie_complete - report completion of a descriptor
  80  * vd: virtual descriptor to update
  81  *
  82  * vc.lock must be held by caller
  83  */
  84 static inline void vchan_cookie_complete(struct virt_dma_desc *vd)
  85 {
  86         struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
  87         dma_cookie_t cookie;
  88
  89         cookie = vd->tx.cookie;
  90         dma_cookie_complete(&vd->tx);
  91         dev_vdbg(vc->chan.device->dev, "txd %p[%x]: marked complete\n",
  92                  vd, cookie);
  93         list_add_tail(&vd->node, &vc->desc_completed);
  94
  95         tasklet_schedule(&vc->task);
  96 }
  97
  98 /**
  99  * vchan_cyclic_callback - report the completion of a period
 100  * vd: virtual descriptor
 101  */
 102 static inline void vchan_cyclic_callback(struct virt_dma_desc *vd)
 103 {
 104         struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
 105
 106         vc->cyclic = vd;
 107         tasklet_schedule(&vc->task);
 108 }
 109
 110 /**
 111  * vchan_next_desc - peek at the next descriptor to be processed
 112  * vc: virtual channel to obtain descriptor from
 113  *
 114  * vc.lock must be held by caller
 115  */
 116 static inline struct virt_dma_desc *vchan_next_desc(struct virt_dma_chan *vc)
 117 {
 118         if (list_empty(&vc->desc_issued))
 119                 return NULL;
 120
 121         return list_first_entry(&vc->desc_issued, struct virt_dma_desc, node);
 122 }
 123
 124 /**
 125  * vchan_get_all_descriptors - obtain all submitted and issued descriptors
 126  * vc: virtual channel to get descriptors from
 127  * head: list of descriptors found
 128  *
 129  * vc.lock must be held by caller
 130  *
 131  * Removes all submitted and issued descriptors from internal lists, and
 132  * provides a list of all descriptors found
 133  */
 134 static inline void vchan_get_all_descriptors(struct virt_dma_chan *vc,
 135         struct list_head *head)
 136 {
 137         list_splice_tail_init(&vc->desc_submitted, head);
 138         list_splice_tail_init(&vc->desc_issued, head);
 139         list_splice_tail_init(&vc->desc_completed, head);
 140 }
 141
 142 static inline void vchan_free_chan_resources(struct virt_dma_chan *vc)
 143 {
 144         unsigned long flags;
 145         LIST_HEAD(head);
 146
 147         spin_lock_irqsave(&vc->lock, flags);
 148         vchan_get_all_descriptors(vc, &head);
 149         spin_unlock_irqrestore(&vc->lock, flags);
 150
 151         vchan_dma_desc_free_list(vc, &head);
 152 }
 153
 154 #endif