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(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(&vd->node, &vc->desc_submitted);
30	spin_unlock_irqrestore(&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(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(&vd->node);
57	spin_unlock_irqrestore(&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(&vc->lock);
91	list_splice_tail_init(&vc->desc_completed, &head);
92	vd = vc->cyclic;
93	if (vd) {
94		vc->cyclic = NULL;
95		dmaengine_desc_get_callback(&vd->tx, &cb);
96	} else {
97		memset(&cb, 0, sizeof(cb));
98	}
99	spin_unlock_irq(&vc->lock);
100
101	dmaengine_desc_callback_invoke(&cb, &vd->tx_result);
102
103	list_for_each_entry_safe(vd, _vd, &head, node) {
104		dmaengine_desc_get_callback(&vd->tx, &cb);
105
106		list_del(&vd->node);
107		dmaengine_desc_callback_invoke(&cb, &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(&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(&vc->chan);
126
127	spin_lock_init(&vc->lock);
128	INIT_LIST_HEAD(&vc->desc_allocated);
129	INIT_LIST_HEAD(&vc->desc_submitted);
130	INIT_LIST_HEAD(&vc->desc_issued);
131	INIT_LIST_HEAD(&vc->desc_completed);
132	INIT_LIST_HEAD(&vc->desc_terminated);
133
134	tasklet_setup(&vc->task, vchan_complete);
135
136	vc->chan.device = dmadev;
137	list_add_tail(&vc->chan.device_node, &dmadev->channels);
138}
139EXPORT_SYMBOL_GPL(vchan_init);
140
141MODULE_AUTHOR("Russell King");
142MODULE_LICENSE("GPL");
143