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
  88         dma_cookie_complete(&vd->tx);
  89         dev_vdbg(vc->chan.device->dev, "txd %p[%x]: marked complete\n",
  90                 vd, vd->tx.cookie);
  91         list_add_tail(&vd->node, &vc->desc_completed);
  92
  93         tasklet_schedule(&vc->task);
  94 }
  95
  96 /**
  97  * vchan_cyclic_callback - report the completion of a period
  98  * vd: virtual descriptor
  99  */
 100 static inline void vchan_cyclic_callback(struct virt_dma_desc *vd)
 101 {
 102         struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
 103
 104         vc->cyclic = vd;
 105         tasklet_schedule(&vc->task);
 106 }
 107
 108 /**
 109  * vchan_next_desc - peek at the next descriptor to be processed
 110  * vc: virtual channel to obtain descriptor from
 111  *
 112  * vc.lock must be held by caller
 113  */
 114 static inline struct virt_dma_desc *vchan_next_desc(struct virt_dma_chan *vc)
 115 {
 116         if (list_empty(&vc->desc_issued))
 117                 return NULL;
 118
 119         return list_first_entry(&vc->desc_issued, struct virt_dma_desc, node);
 120 }
 121
 122 /**
 123  * vchan_get_all_descriptors - obtain all submitted and issued descriptors
 124  * vc: virtual channel to get descriptors from
 125  * head: list of descriptors found
 126  *
 127  * vc.lock must be held by caller
 128  *
 129  * Removes all submitted and issued descriptors from internal lists, and
 130  * provides a list of all descriptors found
 131  */
 132 static inline void vchan_get_all_descriptors(struct virt_dma_chan *vc,
 133         struct list_head *head)
 134 {
 135         list_splice_tail_init(&vc->desc_submitted, head);
 136         list_splice_tail_init(&vc->desc_issued, head);
 137         list_splice_tail_init(&vc->desc_completed, head);
 138 }
 139
 140 static inline void vchan_free_chan_resources(struct virt_dma_chan *vc)
 141 {
 142         unsigned long flags;
 143         LIST_HEAD(head);
 144
 145         spin_lock_irqsave(&vc->lock, flags);
 146         vchan_get_all_descriptors(vc, &head);
 147         spin_unlock_irqrestore(&vc->lock, flags);
 148
 149         vchan_dma_desc_free_list(vc, &head);
 150 }
 151
 152 #endif