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#ifndef VIRT_DMA_H
8#define VIRT_DMA_H
9
10#include <linux/dmaengine.h>
11#include <linux/interrupt.h>
12
13#include "dmaengine.h"
14
15struct virt_dma_desc {
16 struct dma_async_tx_descriptor tx;
17 struct dmaengine_result tx_result;
18 /* protected by vc.lock */
19 struct list_head node;
20};
21
22struct virt_dma_chan {
23 struct dma_chan chan;
24 struct tasklet_struct task;
25 void (*desc_free)(struct virt_dma_desc *);
26
27 spinlock_t lock;
28
29 /* protected by vc.lock */
30 struct list_head desc_allocated;
31 struct list_head desc_submitted;
32 struct list_head desc_issued;
33 struct list_head desc_completed;
34 struct list_head desc_terminated;
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);
47extern dma_cookie_t vchan_tx_submit(struct dma_async_tx_descriptor *);
48extern int vchan_tx_desc_free(struct dma_async_tx_descriptor *);
49
50/**
51 * vchan_tx_prep - prepare a descriptor
52 * @vc: virtual channel allocating this descriptor
53 * @vd: virtual descriptor to prepare
54 * @tx_flags: flags argument passed in to prepare function
55 */
56static inline struct dma_async_tx_descriptor *vchan_tx_prep(struct virt_dma_chan *vc,
57 struct virt_dma_desc *vd, unsigned long tx_flags)
58{
59 unsigned long flags;
60
61 dma_async_tx_descriptor_init(tx: &vd->tx, chan: &vc->chan);
62 vd->tx.flags = tx_flags;
63 vd->tx.tx_submit = vchan_tx_submit;
64 vd->tx.desc_free = vchan_tx_desc_free;
65
66 vd->tx_result.result = DMA_TRANS_NOERROR;
67 vd->tx_result.residue = 0;
68
69 spin_lock_irqsave(&vc->lock, flags);
70 list_add_tail(new: &vd->node, head: &vc->desc_allocated);
71 spin_unlock_irqrestore(lock: &vc->lock, flags);
72
73 return &vd->tx;
74}
75
76/**
77 * vchan_issue_pending - move submitted descriptors to issued list
78 * @vc: virtual channel to update
79 *
80 * vc.lock must be held by caller
81 */
82static inline bool vchan_issue_pending(struct virt_dma_chan *vc)
83{
84 lockdep_assert_held(&vc->lock);
85
86 list_splice_tail_init(list: &vc->desc_submitted, head: &vc->desc_issued);
87 return !list_empty(head: &vc->desc_issued);
88}
89
90/**
91 * vchan_cookie_complete - report completion of a descriptor
92 * @vd: virtual descriptor to update
93 *
94 * vc.lock must be held by caller
95 */
96static inline void vchan_cookie_complete(struct virt_dma_desc *vd)
97{
98 struct virt_dma_chan *vc = to_virt_chan(chan: vd->tx.chan);
99 dma_cookie_t cookie;
100
101 lockdep_assert_held(&vc->lock);
102
103 cookie = vd->tx.cookie;
104 dma_cookie_complete(tx: &vd->tx);
105 dev_vdbg(vc->chan.device->dev, "txd %p[%x]: marked complete\n",
106 vd, cookie);
107 list_add_tail(new: &vd->node, head: &vc->desc_completed);
108
109 tasklet_schedule(t: &vc->task);
110}
111
112/**
113 * vchan_vdesc_fini - Free or reuse a descriptor
114 * @vd: virtual descriptor to free/reuse
115 */
116static inline void vchan_vdesc_fini(struct virt_dma_desc *vd)
117{
118 struct virt_dma_chan *vc = to_virt_chan(chan: vd->tx.chan);
119
120 if (dmaengine_desc_test_reuse(tx: &vd->tx)) {
121 unsigned long flags;
122
123 spin_lock_irqsave(&vc->lock, flags);
124 list_add(new: &vd->node, head: &vc->desc_allocated);
125 spin_unlock_irqrestore(lock: &vc->lock, flags);
126 } else {
127 vc->desc_free(vd);
128 }
129}
130
131/**
132 * vchan_cyclic_callback - report the completion of a period
133 * @vd: virtual descriptor
134 */
135static inline void vchan_cyclic_callback(struct virt_dma_desc *vd)
136{
137 struct virt_dma_chan *vc = to_virt_chan(chan: vd->tx.chan);
138
139 vc->cyclic = vd;
140 tasklet_schedule(t: &vc->task);
141}
142
143/**
144 * vchan_terminate_vdesc - Disable pending cyclic callback
145 * @vd: virtual descriptor to be terminated
146 *
147 * vc.lock must be held by caller
148 */
149static inline void vchan_terminate_vdesc(struct virt_dma_desc *vd)
150{
151 struct virt_dma_chan *vc = to_virt_chan(chan: vd->tx.chan);
152
153 lockdep_assert_held(&vc->lock);
154
155 list_add_tail(new: &vd->node, head: &vc->desc_terminated);
156
157 if (vc->cyclic == vd)
158 vc->cyclic = NULL;
159}
160
161/**
162 * vchan_next_desc - peek at the next descriptor to be processed
163 * @vc: virtual channel to obtain descriptor from
164 *
165 * vc.lock must be held by caller
166 */
167static inline struct virt_dma_desc *vchan_next_desc(struct virt_dma_chan *vc)
168{
169 lockdep_assert_held(&vc->lock);
170
171 return list_first_entry_or_null(&vc->desc_issued,
172 struct virt_dma_desc, node);
173}
174
175/**
176 * vchan_get_all_descriptors - obtain all submitted and issued descriptors
177 * @vc: virtual channel to get descriptors from
178 * @head: list of descriptors found
179 *
180 * vc.lock must be held by caller
181 *
182 * Removes all submitted and issued descriptors from internal lists, and
183 * provides a list of all descriptors found
184 */
185static inline void vchan_get_all_descriptors(struct virt_dma_chan *vc,
186 struct list_head *head)
187{
188 lockdep_assert_held(&vc->lock);
189
190 list_splice_tail_init(list: &vc->desc_allocated, head);
191 list_splice_tail_init(list: &vc->desc_submitted, head);
192 list_splice_tail_init(list: &vc->desc_issued, head);
193 list_splice_tail_init(list: &vc->desc_completed, head);
194 list_splice_tail_init(list: &vc->desc_terminated, head);
195}
196
197static inline void vchan_free_chan_resources(struct virt_dma_chan *vc)
198{
199 struct virt_dma_desc *vd;
200 unsigned long flags;
201 LIST_HEAD(head);
202
203 spin_lock_irqsave(&vc->lock, flags);
204 vchan_get_all_descriptors(vc, head: &head);
205 list_for_each_entry(vd, &head, node)
206 dmaengine_desc_clear_reuse(tx: &vd->tx);
207 spin_unlock_irqrestore(lock: &vc->lock, flags);
208
209 vchan_dma_desc_free_list(vc, head: &head);
210}
211
212/**
213 * vchan_synchronize() - synchronize callback execution to the current context
214 * @vc: virtual channel to synchronize
215 *
216 * Makes sure that all scheduled or active callbacks have finished running. For
217 * proper operation the caller has to ensure that no new callbacks are scheduled
218 * after the invocation of this function started.
219 * Free up the terminated cyclic descriptor to prevent memory leakage.
220 */
221static inline void vchan_synchronize(struct virt_dma_chan *vc)
222{
223 LIST_HEAD(head);
224 unsigned long flags;
225
226 tasklet_kill(t: &vc->task);
227
228 spin_lock_irqsave(&vc->lock, flags);
229
230 list_splice_tail_init(list: &vc->desc_terminated, head: &head);
231
232 spin_unlock_irqrestore(lock: &vc->lock, flags);
233
234 vchan_dma_desc_free_list(vc, head: &head);
235}
236
237#endif
238