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
 35	struct virt_dma_desc *cyclic;
 36	struct virt_dma_desc *vd_terminated;
 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		list_add(&vd->node, &vc->desc_allocated);
118	else
119		vc->desc_free(vd);
120}
121
122/**
123 * vchan_cyclic_callback - report the completion of a period
124 * @vd: virtual descriptor
125 */
126static inline void vchan_cyclic_callback(struct virt_dma_desc *vd)
127{
128	struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
129
130	vc->cyclic = vd;
131	tasklet_schedule(&vc->task);
132}
133
134/**
135 * vchan_terminate_vdesc - Disable pending cyclic callback
136 * @vd: virtual descriptor to be terminated
137 *
138 * vc.lock must be held by caller
139 */
140static inline void vchan_terminate_vdesc(struct virt_dma_desc *vd)
141{
142	struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
143
144	/* free up stuck descriptor */
145	if (vc->vd_terminated)
146		vchan_vdesc_fini(vc->vd_terminated);
147
148	vc->vd_terminated = vd;
149	if (vc->cyclic == vd)
150		vc->cyclic = NULL;
151}
152
153/**
154 * vchan_next_desc - peek at the next descriptor to be processed
155 * @vc: virtual channel to obtain descriptor from
156 *
157 * vc.lock must be held by caller
158 */
159static inline struct virt_dma_desc *vchan_next_desc(struct virt_dma_chan *vc)
160{
161	return list_first_entry_or_null(&vc->desc_issued,
162					struct virt_dma_desc, node);
163}
164
165/**
166 * vchan_get_all_descriptors - obtain all submitted and issued descriptors
167 * @vc: virtual channel to get descriptors from
168 * @head: list of descriptors found
169 *
170 * vc.lock must be held by caller
171 *
172 * Removes all submitted and issued descriptors from internal lists, and
173 * provides a list of all descriptors found
174 */
175static inline void vchan_get_all_descriptors(struct virt_dma_chan *vc,
176	struct list_head *head)
177{
178	list_splice_tail_init(&vc->desc_allocated, head);
179	list_splice_tail_init(&vc->desc_submitted, head);
180	list_splice_tail_init(&vc->desc_issued, head);
181	list_splice_tail_init(&vc->desc_completed, head);
182}
183
184static inline void vchan_free_chan_resources(struct virt_dma_chan *vc)
185{
186	struct virt_dma_desc *vd;
187	unsigned long flags;
188	LIST_HEAD(head);
189
190	spin_lock_irqsave(&vc->lock, flags);
191	vchan_get_all_descriptors(vc, &head);
192	list_for_each_entry(vd, &head, node)
193		dmaengine_desc_clear_reuse(&vd->tx);
194	spin_unlock_irqrestore(&vc->lock, flags);
195
196	vchan_dma_desc_free_list(vc, &head);
197}
198
199/**
200 * vchan_synchronize() - synchronize callback execution to the current context
201 * @vc: virtual channel to synchronize
202 *
203 * Makes sure that all scheduled or active callbacks have finished running. For
204 * proper operation the caller has to ensure that no new callbacks are scheduled
205 * after the invocation of this function started.
206 * Free up the terminated cyclic descriptor to prevent memory leakage.
207 */
208static inline void vchan_synchronize(struct virt_dma_chan *vc)
209{
210	unsigned long flags;
211
212	tasklet_kill(&vc->task);
213
214	spin_lock_irqsave(&vc->lock, flags);
215	if (vc->vd_terminated) {
216		vchan_vdesc_fini(vc->vd_terminated);
217		vc->vd_terminated = NULL;
218	}
219	spin_unlock_irqrestore(&vc->lock, flags);
220}
221
222#endif