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 
15 struct 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 
22 struct 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 
to_virt_chan(struct dma_chan * chan)39 static 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 
44 void vchan_dma_desc_free_list(struct virt_dma_chan *vc, struct list_head *head);
45 void vchan_init(struct virt_dma_chan *vc, struct dma_device *dmadev);
46 struct virt_dma_desc *vchan_find_desc(struct virt_dma_chan *, dma_cookie_t);
47 extern dma_cookie_t vchan_tx_submit(struct dma_async_tx_descriptor *);
48 extern 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  */
vchan_tx_prep(struct virt_dma_chan * vc,struct virt_dma_desc * vd,unsigned long tx_flags)56 static 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  */
vchan_issue_pending(struct virt_dma_chan * vc)82 static inline bool vchan_issue_pending(struct virt_dma_chan *vc)
83 {
84 	lockdep_assert_held(&vc->lock);
85 
86 	list_splice_tail_init(&vc->desc_submitted, &vc->desc_issued);
87 	return !list_empty(&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  */
vchan_cookie_complete(struct virt_dma_desc * vd)96 static inline void vchan_cookie_complete(struct virt_dma_desc *vd)
97 {
98 	struct virt_dma_chan *vc = to_virt_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(&vd->tx);
105 	dev_vdbg(vc->chan.device->dev, "txd %p[%x]: marked complete\n",
106 		 vd, cookie);
107 	list_add_tail(&vd->node, &vc->desc_completed);
108 
109 	tasklet_schedule(&vc->task);
110 }
111 
112 /**
113  * vchan_vdesc_fini - Free or reuse a descriptor
114  * @vd: virtual descriptor to free/reuse
115  */
vchan_vdesc_fini(struct virt_dma_desc * vd)116 static inline void vchan_vdesc_fini(struct virt_dma_desc *vd)
117 {
118 	struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
119 
120 	if (dmaengine_desc_test_reuse(&vd->tx)) {
121 		unsigned long flags;
122 
123 		spin_lock_irqsave(&vc->lock, flags);
124 		list_add(&vd->node, &vc->desc_allocated);
125 		spin_unlock_irqrestore(&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  */
vchan_cyclic_callback(struct virt_dma_desc * vd)135 static inline void vchan_cyclic_callback(struct virt_dma_desc *vd)
136 {
137 	struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
138 
139 	vc->cyclic = vd;
140 	tasklet_schedule(&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  */
vchan_terminate_vdesc(struct virt_dma_desc * vd)149 static inline void vchan_terminate_vdesc(struct virt_dma_desc *vd)
150 {
151 	struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
152 
153 	lockdep_assert_held(&vc->lock);
154 
155 	list_add_tail(&vd->node, &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  */
vchan_next_desc(struct virt_dma_chan * vc)167 static 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  */
vchan_get_all_descriptors(struct virt_dma_chan * vc,struct list_head * head)185 static 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(&vc->desc_allocated, head);
191 	list_splice_tail_init(&vc->desc_submitted, head);
192 	list_splice_tail_init(&vc->desc_issued, head);
193 	list_splice_tail_init(&vc->desc_completed, head);
194 	list_splice_tail_init(&vc->desc_terminated, head);
195 }
196 
vchan_free_chan_resources(struct virt_dma_chan * vc)197 static 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);
205 	list_for_each_entry(vd, &head, node)
206 		dmaengine_desc_clear_reuse(&vd->tx);
207 	spin_unlock_irqrestore(&vc->lock, flags);
208 
209 	vchan_dma_desc_free_list(vc, &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  */
vchan_synchronize(struct virt_dma_chan * vc)221 static inline void vchan_synchronize(struct virt_dma_chan *vc)
222 {
223 	LIST_HEAD(head);
224 	unsigned long flags;
225 
226 	tasklet_kill(&vc->task);
227 
228 	spin_lock_irqsave(&vc->lock, flags);
229 
230 	list_splice_tail_init(&vc->desc_terminated, &head);
231 
232 	spin_unlock_irqrestore(&vc->lock, flags);
233 
234 	vchan_dma_desc_free_list(vc, &head);
235 }
236 
237 #endif
238