Linux Kernel  3.7.1
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virt-dma.c
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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 #include <linux/device.h>
11 #include <linux/dmaengine.h>
12 #include <linux/module.h>
13 #include <linux/spinlock.h>
14 
15 #include "virt-dma.h"
16 
17 static struct virt_dma_desc *to_virt_desc(struct dma_async_tx_descriptor *tx)
18 {
19  return container_of(tx, struct virt_dma_desc, tx);
20 }
21 
22 dma_cookie_t vchan_tx_submit(struct dma_async_tx_descriptor *tx)
23 {
24  struct virt_dma_chan *vc = to_virt_chan(tx->chan);
25  struct virt_dma_desc *vd = to_virt_desc(tx);
26  unsigned long flags;
27  dma_cookie_t cookie;
28 
29  spin_lock_irqsave(&vc->lock, flags);
30  cookie = dma_cookie_assign(tx);
31 
32  list_add_tail(&vd->node, &vc->desc_submitted);
33  spin_unlock_irqrestore(&vc->lock, flags);
34 
35  dev_dbg(vc->chan.device->dev, "vchan %p: txd %p[%x]: submitted\n",
36  vc, vd, cookie);
37 
38  return cookie;
39 }
40 EXPORT_SYMBOL_GPL(vchan_tx_submit);
41 
42 struct virt_dma_desc *vchan_find_desc(struct virt_dma_chan *vc,
43  dma_cookie_t cookie)
44 {
45  struct virt_dma_desc *vd;
46 
47  list_for_each_entry(vd, &vc->desc_issued, node)
48  if (vd->tx.cookie == cookie)
49  return vd;
50 
51  return NULL;
52 }
53 EXPORT_SYMBOL_GPL(vchan_find_desc);
54 
55 /*
56  * This tasklet handles the completion of a DMA descriptor by
57  * calling its callback and freeing it.
58  */
59 static void vchan_complete(unsigned long arg)
60 {
61  struct virt_dma_chan *vc = (struct virt_dma_chan *)arg;
62  struct virt_dma_desc *vd;
63  dma_async_tx_callback cb = NULL;
64  void *cb_data = NULL;
65  LIST_HEAD(head);
66 
67  spin_lock_irq(&vc->lock);
68  list_splice_tail_init(&vc->desc_completed, &head);
69  vd = vc->cyclic;
70  if (vd) {
71  vc->cyclic = NULL;
72  cb = vd->tx.callback;
73  cb_data = vd->tx.callback_param;
74  }
75  spin_unlock_irq(&vc->lock);
76 
77  if (cb)
78  cb(cb_data);
79 
80  while (!list_empty(&head)) {
81  vd = list_first_entry(&head, struct virt_dma_desc, node);
82  cb = vd->tx.callback;
83  cb_data = vd->tx.callback_param;
84 
85  list_del(&vd->node);
86 
87  vc->desc_free(vd);
88 
89  if (cb)
90  cb(cb_data);
91  }
92 }
93 
94 void vchan_dma_desc_free_list(struct virt_dma_chan *vc, struct list_head *head)
95 {
96  while (!list_empty(head)) {
97  struct virt_dma_desc *vd = list_first_entry(head,
98  struct virt_dma_desc, node);
99  list_del(&vd->node);
100  dev_dbg(vc->chan.device->dev, "txd %p: freeing\n", vd);
101  vc->desc_free(vd);
102  }
103 }
104 EXPORT_SYMBOL_GPL(vchan_dma_desc_free_list);
105 
106 void vchan_init(struct virt_dma_chan *vc, struct dma_device *dmadev)
107 {
108  dma_cookie_init(&vc->chan);
109 
110  spin_lock_init(&vc->lock);
111  INIT_LIST_HEAD(&vc->desc_submitted);
112  INIT_LIST_HEAD(&vc->desc_issued);
113  INIT_LIST_HEAD(&vc->desc_completed);
114 
115  tasklet_init(&vc->task, vchan_complete, (unsigned long)vc);
116 
117  vc->chan.device = dmadev;
118  list_add_tail(&vc->chan.device_node, &dmadev->channels);
119 }
120 EXPORT_SYMBOL_GPL(vchan_init);
121 
122 MODULE_AUTHOR("Russell King");
123 MODULE_LICENSE("GPL");
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