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_allocated;
  33         struct list_head desc_submitted;
  34         struct list_head desc_issued;
  35         struct list_head desc_completed;
  36
  37         struct virt_dma_desc *cyclic;
  38 };
  39
  40 static inline struct virt_dma_chan *to_virt_chan(struct dma_chan *chan)
  41 {
  42         return container_of(chan, struct virt_dma_chan, chan);
  43 }
  44
  45 void vchan_dma_desc_free_list(struct virt_dma_chan *vc, struct list_head *head);
  46 void vchan_init(struct virt_dma_chan *vc, struct dma_device *dmadev);
  47 struct virt_dma_desc *vchan_find_desc(struct virt_dma_chan *, dma_cookie_t);
  48
  49 /**
  50  * vchan_tx_prep - prepare a descriptor
  51  * vc: virtual channel allocating this descriptor
  52  * vd: virtual descriptor to prepare
  53  * tx_flags: flags argument passed in to prepare function
  54  */
  55 static inline struct dma_async_tx_descriptor *vchan_tx_prep(struct virt_dma_chan *vc,
  56         struct virt_dma_desc *vd, unsigned long tx_flags)
  57 {
  58         extern dma_cookie_t vchan_tx_submit(struct dma_async_tx_descriptor *);
  59         unsigned long flags;
  60
  61         dma_async_tx_descriptor_init(&vd->tx, &vc->chan);
  62         vd->tx.flags = tx_flags;
  63         vd->tx.tx_submit = vchan_tx_submit;
  64
  65         spin_lock_irqsave(&vc->lock, flags);
  66         list_add_tail(&vd->node, &vc->desc_allocated);
  67         spin_unlock_irqrestore(&vc->lock, flags);
  68
  69         return &vd->tx;
  70 }
  71
  72 /**
  73  * vchan_issue_pending - move submitted descriptors to issued list
  74  * vc: virtual channel to update
  75  *
  76  * vc.lock must be held by caller
  77  */
  78 static inline bool vchan_issue_pending(struct virt_dma_chan *vc)
  79 {
  80         list_splice_tail_init(&vc->desc_submitted, &vc->desc_issued);
  81         return !list_empty(&vc->desc_issued);
  82 }
  83
  84 /**
  85  * vchan_cookie_complete - report completion of a descriptor
  86  * vd: virtual descriptor to update
  87  *
  88  * vc.lock must be held by caller
  89  */
  90 static inline void vchan_cookie_complete(struct virt_dma_desc *vd)
  91 {
  92         struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
  93         dma_cookie_t cookie;
  94
  95         cookie = vd->tx.cookie;
  96         dma_cookie_complete(&vd->tx);
  97         dev_vdbg(vc->chan.device->dev, "txd %p[%x]: marked complete\n",
  98                  vd, cookie);
  99         list_add_tail(&vd->node, &vc->desc_completed);
 100
 101         tasklet_schedule(&vc->task);
 102 }
 103
 104 /**
 105  * vchan_cyclic_callback - report the completion of a period
 106  * vd: virtual descriptor
 107  */
 108 static inline void vchan_cyclic_callback(struct virt_dma_desc *vd)
 109 {
 110         struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
 111
 112         vc->cyclic = vd;
 113         tasklet_schedule(&vc->task);
 114 }
 115
 116 /**
 117  * vchan_next_desc - peek at the next descriptor to be processed
 118  * vc: virtual channel to obtain descriptor from
 119  *
 120  * vc.lock must be held by caller
 121  */
 122 static inline struct virt_dma_desc *vchan_next_desc(struct virt_dma_chan *vc)
 123 {
 124         if (list_empty(&vc->desc_issued))
 125                 return NULL;
 126
 127         return list_first_entry(&vc->desc_issued, struct virt_dma_desc, node);
 128 }
 129
 130 /**
 131  * vchan_get_all_descriptors - obtain all allocated, submitted and issued
 132  *                             descriptors
 133  * vc: virtual channel to get descriptors from
 134  * head: list of descriptors found
 135  *
 136  * vc.lock must be held by caller
 137  *
 138  * Removes all submitted and issued descriptors from internal lists, and
 139  * provides a list of all descriptors found
 140  */
 141 static inline void vchan_get_all_descriptors(struct virt_dma_chan *vc,
 142         struct list_head *head)
 143 {
 144         list_splice_tail_init(&vc->desc_allocated, head);
 145         list_splice_tail_init(&vc->desc_submitted, head);
 146         list_splice_tail_init(&vc->desc_issued, head);
 147         list_splice_tail_init(&vc->desc_completed, head);
 148 }
 149
 150 static inline void vchan_free_chan_resources(struct virt_dma_chan *vc)
 151 {
 152         struct virt_dma_desc *vd;
 153         unsigned long flags;
 154         LIST_HEAD(head);
 155
 156         spin_lock_irqsave(&vc->lock, flags);
 157         vchan_get_all_descriptors(vc, &head);
 158         list_for_each_entry(vd, &head, node)
 159                 async_tx_clear_ack(&vd->tx);
 160         spin_unlock_irqrestore(&vc->lock, flags);
 161
 162         vchan_dma_desc_free_list(vc, &head);
 163 }
 164
 165 #endif