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
to_virt_desc(struct dma_async_tx_descriptor * tx)14 static 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
vchan_tx_submit(struct dma_async_tx_descriptor * tx)19 dma_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 }
37 EXPORT_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 */
vchan_tx_desc_free(struct dma_async_tx_descriptor * tx)49 int 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 }
64 EXPORT_SYMBOL_GPL(vchan_tx_desc_free);
65
vchan_find_desc(struct virt_dma_chan * vc,dma_cookie_t cookie)66 struct 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 }
77 EXPORT_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 */
vchan_complete(struct tasklet_struct * t)83 static 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
vchan_dma_desc_free_list(struct virt_dma_chan * vc,struct list_head * head)112 void 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 }
121 EXPORT_SYMBOL_GPL(vchan_dma_desc_free_list);
122
vchan_init(struct virt_dma_chan * vc,struct dma_device * dmadev)123 void 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 }
139 EXPORT_SYMBOL_GPL(vchan_init);
140
141 MODULE_AUTHOR("Russell King");
142 MODULE_LICENSE("GPL");
143