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
to_virt_desc(struct dma_async_tx_descriptor * tx)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
vchan_tx_submit(struct dma_async_tx_descriptor * tx)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
vchan_find_desc(struct virt_dma_chan * vc,dma_cookie_t cookie)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 */
vchan_complete(unsigned long arg)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
vchan_dma_desc_free_list(struct virt_dma_chan * vc,struct list_head * head)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
vchan_init(struct virt_dma_chan * vc,struct dma_device * dmadev)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");
124