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#include <linux/device.h>
11#include <linux/dmaengine.h>
12#include <linux/module.h>
13#include <linux/spinlock.h>
14
15#include "virt-dma.h"
16
17static struct virt_dma_desc *to_virt_desc(struct dma_async_tx_descriptor *tx)
18{
19	return container_of(tx, struct virt_dma_desc, tx);
20}
21
22dma_cookie_t vchan_tx_submit(struct dma_async_tx_descriptor *tx)
23{
24	struct virt_dma_chan *vc = to_virt_chan(tx->chan);
25	struct virt_dma_desc *vd = to_virt_desc(tx);
26	unsigned long flags;
27	dma_cookie_t cookie;
28
29	spin_lock_irqsave(&vc->lock, flags);
30	cookie = dma_cookie_assign(tx);
31
32	list_add_tail(&vd->node, &vc->desc_submitted);
33	spin_unlock_irqrestore(&vc->lock, flags);
34
35	dev_dbg(vc->chan.device->dev, "vchan %p: txd %p[%x]: submitted\n",
36		vc, vd, cookie);
37
38	return cookie;
39}
40EXPORT_SYMBOL_GPL(vchan_tx_submit);
41
42struct virt_dma_desc *vchan_find_desc(struct virt_dma_chan *vc,
43	dma_cookie_t cookie)
44{
45	struct virt_dma_desc *vd;
46
47	list_for_each_entry(vd, &vc->desc_issued, node)
48		if (vd->tx.cookie == cookie)
49			return vd;
50
51	return NULL;
52}
53EXPORT_SYMBOL_GPL(vchan_find_desc);
54
55/*
56 * This tasklet handles the completion of a DMA descriptor by
57 * calling its callback and freeing it.
58 */
59static void vchan_complete(unsigned long arg)
60{
61	struct virt_dma_chan *vc = (struct virt_dma_chan *)arg;
62	struct virt_dma_desc *vd;
63	dma_async_tx_callback cb = NULL;
64	void *cb_data = NULL;
65	LIST_HEAD(head);
66
67	spin_lock_irq(&vc->lock);
68	list_splice_tail_init(&vc->desc_completed, &head);
69	vd = vc->cyclic;
70	if (vd) {
71		vc->cyclic = NULL;
72		cb = vd->tx.callback;
73		cb_data = vd->tx.callback_param;
74	}
75	spin_unlock_irq(&vc->lock);
76
77	if (cb)
78		cb(cb_data);
79
80	while (!list_empty(&head)) {
81		vd = list_first_entry(&head, struct virt_dma_desc, node);
82		cb = vd->tx.callback;
83		cb_data = vd->tx.callback_param;
84
85		list_del(&vd->node);
86
87		vc->desc_free(vd);
88
89		if (cb)
90			cb(cb_data);
91	}
92}
93
94void vchan_dma_desc_free_list(struct virt_dma_chan *vc, struct list_head *head)
95{
96	while (!list_empty(head)) {
97		struct virt_dma_desc *vd = list_first_entry(head,
98			struct virt_dma_desc, node);
99		list_del(&vd->node);
100		dev_dbg(vc->chan.device->dev, "txd %p: freeing\n", vd);
101		vc->desc_free(vd);
102	}
103}
104EXPORT_SYMBOL_GPL(vchan_dma_desc_free_list);
105
106void vchan_init(struct virt_dma_chan *vc, struct dma_device *dmadev)
107{
108	dma_cookie_init(&vc->chan);
109
110	spin_lock_init(&vc->lock);
111	INIT_LIST_HEAD(&vc->desc_submitted);
112	INIT_LIST_HEAD(&vc->desc_issued);
113	INIT_LIST_HEAD(&vc->desc_completed);
114
115	tasklet_init(&vc->task, vchan_complete, (unsigned long)vc);
116
117	vc->chan.device = dmadev;
118	list_add_tail(&vc->chan.device_node, &dmadev->channels);
119}
120EXPORT_SYMBOL_GPL(vchan_init);
121
122MODULE_AUTHOR("Russell King");
123MODULE_LICENSE("GPL");
124