tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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
18struct virt_dma_desc {
19 struct dma_async_tx_descriptor tx;
20 /* protected by vc.lock */
21 struct list_head node;
22};
23
24struct 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
40static 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
45void vchan_dma_desc_free_list(struct virt_dma_chan *vc, struct list_head *head);
46void vchan_init(struct virt_dma_chan *vc, struct dma_device *dmadev);
47struct 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 */
55static 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 extern int vchan_tx_desc_free(struct dma_async_tx_descriptor *);
60 unsigned long flags;
61
62 dma_async_tx_descriptor_init(&vd->tx, &vc->chan);
63 vd->tx.flags = tx_flags;
64 vd->tx.tx_submit = vchan_tx_submit;
65 vd->tx.desc_free = vchan_tx_desc_free;
66
67 spin_lock_irqsave(&vc->lock, flags);
68 list_add_tail(&vd->node, &vc->desc_allocated);
69 spin_unlock_irqrestore(&vc->lock, flags);
70
71 return &vd->tx;
72}
73
74/**
75 * vchan_issue_pending - move submitted descriptors to issued list
76 * @vc: virtual channel to update
77 *
78 * vc.lock must be held by caller
79 */
80static inline bool vchan_issue_pending(struct virt_dma_chan *vc)
81{
82 list_splice_tail_init(&vc->desc_submitted, &vc->desc_issued);
83 return !list_empty(&vc->desc_issued);
84}
85
86/**
87 * vchan_cookie_complete - report completion of a descriptor
88 * @vd: virtual descriptor to update
89 *
90 * vc.lock must be held by caller
91 */
92static inline void vchan_cookie_complete(struct virt_dma_desc *vd)
93{
94 struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
95 dma_cookie_t cookie;
96
97 cookie = vd->tx.cookie;
98 dma_cookie_complete(&vd->tx);
99 dev_vdbg(vc->chan.device->dev, "txd %p[%x]: marked complete\n",
100 vd, cookie);
101 list_add_tail(&vd->node, &vc->desc_completed);
102
103 tasklet_schedule(&vc->task);
104}
105
106/**
107 * vchan_cyclic_callback - report the completion of a period
108 * @vd: virtual descriptor
109 */
110static inline void vchan_cyclic_callback(struct virt_dma_desc *vd)
111{
112 struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
113
114 vc->cyclic = vd;
115 tasklet_schedule(&vc->task);
116}
117
118/**
119 * vchan_next_desc - peek at the next descriptor to be processed
120 * @vc: virtual channel to obtain descriptor from
121 *
122 * vc.lock must be held by caller
123 */
124static inline struct virt_dma_desc *vchan_next_desc(struct virt_dma_chan *vc)
125{
126 if (list_empty(&vc->desc_issued))
127 return NULL;
128
129 return list_first_entry(&vc->desc_issued, struct virt_dma_desc, node);
130}
131
132/**
133 * vchan_get_all_descriptors - obtain all submitted and issued descriptors
134 * @vc: virtual channel to get descriptors from
135 * @head: list of descriptors found
136 *
137 * vc.lock must be held by caller
138 *
139 * Removes all submitted and issued descriptors from internal lists, and
140 * provides a list of all descriptors found
141 */
142static inline void vchan_get_all_descriptors(struct virt_dma_chan *vc,
143 struct list_head *head)
144{
145 list_splice_tail_init(&vc->desc_allocated, head);
146 list_splice_tail_init(&vc->desc_submitted, head);
147 list_splice_tail_init(&vc->desc_issued, head);
148 list_splice_tail_init(&vc->desc_completed, head);
149}
150
151static inline void vchan_free_chan_resources(struct virt_dma_chan *vc)
152{
153 struct virt_dma_desc *vd;
154 unsigned long flags;
155 LIST_HEAD(head);
156
157 spin_lock_irqsave(&vc->lock, flags);
158 vchan_get_all_descriptors(vc, &head);
159 list_for_each_entry(vd, &head, node)
160 dmaengine_desc_clear_reuse(&vd->tx);
161 spin_unlock_irqrestore(&vc->lock, flags);
162
163 vchan_dma_desc_free_list(vc, &head);
164}
165
166/**
167 * vchan_synchronize() - synchronize callback execution to the current context
168 * @vc: virtual channel to synchronize
169 *
170 * Makes sure that all scheduled or active callbacks have finished running. For
171 * proper operation the caller has to ensure that no new callbacks are scheduled
172 * after the invocation of this function started.
173 */
174static inline void vchan_synchronize(struct virt_dma_chan *vc)
175{
176 tasklet_kill(&vc->task);
177}
178
179#endif