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
to_virt_chan(struct dma_chan * chan)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 */
vchan_tx_prep(struct virt_dma_chan * vc,struct virt_dma_desc * vd,unsigned long tx_flags)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 */
vchan_issue_pending(struct virt_dma_chan * vc)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 */
vchan_cookie_complete(struct virt_dma_desc * vd)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 */
vchan_cyclic_callback(struct virt_dma_desc * vd)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 */
vchan_next_desc(struct virt_dma_chan * vc)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 */
vchan_get_all_descriptors(struct virt_dma_chan * vc,struct list_head * head)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
vchan_free_chan_resources(struct virt_dma_chan * vc)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
155