1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Virtual DMA channel support for DMAengine
4 *
5 * Copyright (C) 2012 Russell King
6 */
7#include <linux/device.h>
8#include <linux/dmaengine.h>
9#include <linux/module.h>
10#include <linux/spinlock.h>
11
12#include "virt-dma.h"
13
14static struct virt_dma_desc *to_virt_desc(struct dma_async_tx_descriptor *tx)
15{
16 return container_of(tx, struct virt_dma_desc, tx);
17}
18
19dma_cookie_t vchan_tx_submit(struct dma_async_tx_descriptor *tx)
20{
21 struct virt_dma_chan *vc = to_virt_chan(chan: tx->chan);
22 struct virt_dma_desc *vd = to_virt_desc(tx);
23 unsigned long flags;
24 dma_cookie_t cookie;
25
26 spin_lock_irqsave(&vc->lock, flags);
27 cookie = dma_cookie_assign(tx);
28
29 list_move_tail(list: &vd->node, head: &vc->desc_submitted);
30 spin_unlock_irqrestore(lock: &vc->lock, flags);
31
32 dev_dbg(vc->chan.device->dev, "vchan %p: txd %p[%x]: submitted\n",
33 vc, vd, cookie);
34
35 return cookie;
36}
37EXPORT_SYMBOL_GPL(vchan_tx_submit);
38
39/**
40 * vchan_tx_desc_free - free a reusable descriptor
41 * @tx: the transfer
42 *
43 * This function frees a previously allocated reusable descriptor. The only
44 * other way is to clear the DMA_CTRL_REUSE flag and submit one last time the
45 * transfer.
46 *
47 * Returns 0 upon success
48 */
49int vchan_tx_desc_free(struct dma_async_tx_descriptor *tx)
50{
51 struct virt_dma_chan *vc = to_virt_chan(chan: tx->chan);
52 struct virt_dma_desc *vd = to_virt_desc(tx);
53 unsigned long flags;
54
55 spin_lock_irqsave(&vc->lock, flags);
56 list_del(entry: &vd->node);
57 spin_unlock_irqrestore(lock: &vc->lock, flags);
58
59 dev_dbg(vc->chan.device->dev, "vchan %p: txd %p[%x]: freeing\n",
60 vc, vd, vd->tx.cookie);
61 vc->desc_free(vd);
62 return 0;
63}
64EXPORT_SYMBOL_GPL(vchan_tx_desc_free);
65
66struct virt_dma_desc *vchan_find_desc(struct virt_dma_chan *vc,
67 dma_cookie_t cookie)
68{
69 struct virt_dma_desc *vd;
70
71 list_for_each_entry(vd, &vc->desc_issued, node)
72 if (vd->tx.cookie == cookie)
73 return vd;
74
75 return NULL;
76}
77EXPORT_SYMBOL_GPL(vchan_find_desc);
78
79/*
80 * This tasklet handles the completion of a DMA descriptor by
81 * calling its callback and freeing it.
82 */
83static void vchan_complete(struct tasklet_struct *t)
84{
85 struct virt_dma_chan *vc = from_tasklet(vc, t, task);
86 struct virt_dma_desc *vd, *_vd;
87 struct dmaengine_desc_callback cb;
88 LIST_HEAD(head);
89
90 spin_lock_irq(lock: &vc->lock);
91 list_splice_tail_init(list: &vc->desc_completed, head: &head);
92 vd = vc->cyclic;
93 if (vd) {
94 vc->cyclic = NULL;
95 dmaengine_desc_get_callback(tx: &vd->tx, cb: &cb);
96 } else {
97 memset(s: &cb, c: 0, n: sizeof(cb));
98 }
99 spin_unlock_irq(lock: &vc->lock);
100
101 dmaengine_desc_callback_invoke(cb: &cb, result: &vd->tx_result);
102
103 list_for_each_entry_safe(vd, _vd, &head, node) {
104 dmaengine_desc_get_callback(tx: &vd->tx, cb: &cb);
105
106 list_del(entry: &vd->node);
107 dmaengine_desc_callback_invoke(cb: &cb, result: &vd->tx_result);
108 vchan_vdesc_fini(vd);
109 }
110}
111
112void vchan_dma_desc_free_list(struct virt_dma_chan *vc, struct list_head *head)
113{
114 struct virt_dma_desc *vd, *_vd;
115
116 list_for_each_entry_safe(vd, _vd, head, node) {
117 list_del(entry: &vd->node);
118 vchan_vdesc_fini(vd);
119 }
120}
121EXPORT_SYMBOL_GPL(vchan_dma_desc_free_list);
122
123void vchan_init(struct virt_dma_chan *vc, struct dma_device *dmadev)
124{
125 dma_cookie_init(chan: &vc->chan);
126
127 spin_lock_init(&vc->lock);
128 INIT_LIST_HEAD(list: &vc->desc_allocated);
129 INIT_LIST_HEAD(list: &vc->desc_submitted);
130 INIT_LIST_HEAD(list: &vc->desc_issued);
131 INIT_LIST_HEAD(list: &vc->desc_completed);
132 INIT_LIST_HEAD(list: &vc->desc_terminated);
133
134 tasklet_setup(t: &vc->task, callback: vchan_complete);
135
136 vc->chan.device = dmadev;
137 list_add_tail(new: &vc->chan.device_node, head: &dmadev->channels);
138}
139EXPORT_SYMBOL_GPL(vchan_init);
140
141MODULE_AUTHOR("Russell King");
142MODULE_DESCRIPTION("Virtual DMA channel support for DMAengine");
143MODULE_LICENSE("GPL");
144