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(&vd->tx, &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(&vd->node, &vc->desc_allocated);
71	spin_unlock_irqrestore(&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	list_splice_tail_init(&vc->desc_submitted, &vc->desc_issued);
85	return !list_empty(&vc->desc_issued);
86}
87
88/**
89 * vchan_cookie_complete - report completion of a descriptor
90 * @vd: virtual descriptor to update
91 *
92 * vc.lock must be held by caller
93 */
94static inline void vchan_cookie_complete(struct virt_dma_desc *vd)
95{
96	struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
97	dma_cookie_t cookie;
98
99	cookie = vd->tx.cookie;
100	dma_cookie_complete(&vd->tx);
101	dev_vdbg(vc->chan.device->dev, "txd %p[%x]: marked complete\n",
102		 vd, cookie);
103	list_add_tail(&vd->node, &vc->desc_completed);
104
105	tasklet_schedule(&vc->task);
106}
107
108/**
109 * vchan_vdesc_fini - Free or reuse a descriptor
110 * @vd: virtual descriptor to free/reuse
111 */
112static inline void vchan_vdesc_fini(struct virt_dma_desc *vd)
113{
114	struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
115
116	if (dmaengine_desc_test_reuse(&vd->tx)) {
117		unsigned long flags;
118
119		spin_lock_irqsave(&vc->lock, flags);
120		list_add(&vd->node, &vc->desc_allocated);
121		spin_unlock_irqrestore(&vc->lock, flags);
122	} else {
123		vc->desc_free(vd);
124	}
125}
126
127/**
128 * vchan_cyclic_callback - report the completion of a period
129 * @vd: virtual descriptor
130 */
131static inline void vchan_cyclic_callback(struct virt_dma_desc *vd)
132{
133	struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
134
135	vc->cyclic = vd;
136	tasklet_schedule(&vc->task);
137}
138
139/**
140 * vchan_terminate_vdesc - Disable pending cyclic callback
141 * @vd: virtual descriptor to be terminated
142 *
143 * vc.lock must be held by caller
144 */
145static inline void vchan_terminate_vdesc(struct virt_dma_desc *vd)
146{
147	struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
148
149	list_add_tail(&vd->node, &vc->desc_terminated);
150
151	if (vc->cyclic == vd)
152		vc->cyclic = NULL;
153}
154
155/**
156 * vchan_next_desc - peek at the next descriptor to be processed
157 * @vc: virtual channel to obtain descriptor from
158 *
159 * vc.lock must be held by caller
160 */
161static inline struct virt_dma_desc *vchan_next_desc(struct virt_dma_chan *vc)
162{
163	return list_first_entry_or_null(&vc->desc_issued,
164					struct virt_dma_desc, node);
165}
166
167/**
168 * vchan_get_all_descriptors - obtain all submitted and issued descriptors
169 * @vc: virtual channel to get descriptors from
170 * @head: list of descriptors found
171 *
172 * vc.lock must be held by caller
173 *
174 * Removes all submitted and issued descriptors from internal lists, and
175 * provides a list of all descriptors found
176 */
177static inline void vchan_get_all_descriptors(struct virt_dma_chan *vc,
178	struct list_head *head)
179{
180	list_splice_tail_init(&vc->desc_allocated, head);
181	list_splice_tail_init(&vc->desc_submitted, head);
182	list_splice_tail_init(&vc->desc_issued, head);
183	list_splice_tail_init(&vc->desc_completed, head);
184	list_splice_tail_init(&vc->desc_terminated, head);
185}
186
187static inline void vchan_free_chan_resources(struct virt_dma_chan *vc)
188{
189	struct virt_dma_desc *vd;
190	unsigned long flags;
191	LIST_HEAD(head);
192
193	spin_lock_irqsave(&vc->lock, flags);
194	vchan_get_all_descriptors(vc, &head);
195	list_for_each_entry(vd, &head, node)
196		dmaengine_desc_clear_reuse(&vd->tx);
197	spin_unlock_irqrestore(&vc->lock, flags);
198
199	vchan_dma_desc_free_list(vc, &head);
200}
201
202/**
203 * vchan_synchronize() - synchronize callback execution to the current context
204 * @vc: virtual channel to synchronize
205 *
206 * Makes sure that all scheduled or active callbacks have finished running. For
207 * proper operation the caller has to ensure that no new callbacks are scheduled
208 * after the invocation of this function started.
209 * Free up the terminated cyclic descriptor to prevent memory leakage.
210 */
211static inline void vchan_synchronize(struct virt_dma_chan *vc)
212{
213	LIST_HEAD(head);
214	unsigned long flags;
215
216	tasklet_kill(&vc->task);
217
218	spin_lock_irqsave(&vc->lock, flags);
219
220	list_splice_tail_init(&vc->desc_terminated, &head);
221
222	spin_unlock_irqrestore(&vc->lock, flags);
223
224	vchan_dma_desc_free_list(vc, &head);
225}
226
227#endif
228