Root/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
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_submitted;
33    struct list_head desc_issued;
34    struct list_head desc_completed;
35
36    struct virt_dma_desc *cyclic;
37};
38
39static 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
44void vchan_dma_desc_free_list(struct virt_dma_chan *vc, struct list_head *head);
45void vchan_init(struct virt_dma_chan *vc, struct dma_device *dmadev);
46struct 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 */
54static 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 */
72static 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 */
84static inline void vchan_cookie_complete(struct virt_dma_desc *vd)
85{
86    struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
87
88    dma_cookie_complete(&vd->tx);
89    dev_vdbg(vc->chan.device->dev, "txd %p[%x]: marked complete\n",
90        vd, vd->tx.cookie);
91    list_add_tail(&vd->node, &vc->desc_completed);
92
93    tasklet_schedule(&vc->task);
94}
95
96/**
97 * vchan_cyclic_callback - report the completion of a period
98 * vd: virtual descriptor
99 */
100static inline void vchan_cyclic_callback(struct virt_dma_desc *vd)
101{
102    struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
103
104    vc->cyclic = vd;
105    tasklet_schedule(&vc->task);
106}
107
108/**
109 * vchan_next_desc - peek at the next descriptor to be processed
110 * vc: virtual channel to obtain descriptor from
111 *
112 * vc.lock must be held by caller
113 */
114static inline struct virt_dma_desc *vchan_next_desc(struct virt_dma_chan *vc)
115{
116    if (list_empty(&vc->desc_issued))
117        return NULL;
118
119    return list_first_entry(&vc->desc_issued, struct virt_dma_desc, node);
120}
121
122/**
123 * vchan_get_all_descriptors - obtain all submitted and issued descriptors
124 * vc: virtual channel to get descriptors from
125 * head: list of descriptors found
126 *
127 * vc.lock must be held by caller
128 *
129 * Removes all submitted and issued descriptors from internal lists, and
130 * provides a list of all descriptors found
131 */
132static inline void vchan_get_all_descriptors(struct virt_dma_chan *vc,
133    struct list_head *head)
134{
135    list_splice_tail_init(&vc->desc_submitted, head);
136    list_splice_tail_init(&vc->desc_issued, head);
137    list_splice_tail_init(&vc->desc_completed, head);
138}
139
140static inline void vchan_free_chan_resources(struct virt_dma_chan *vc)
141{
142    unsigned long flags;
143    LIST_HEAD(head);
144
145    spin_lock_irqsave(&vc->lock, flags);
146    vchan_get_all_descriptors(vc, &head);
147    spin_unlock_irqrestore(&vc->lock, flags);
148
149    vchan_dma_desc_free_list(vc, &head);
150}
151
152#endif
153

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