xref: /openbmc/linux/drivers/dma/virt-dma.h (revision ae213c44)
1 /*
2  * Virtual DMA channel support for DMAengine
3  *
4  * Copyright (C) 2012 Russell King
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License version 2 as
8  * published by the Free Software Foundation.
9  */
10 #ifndef VIRT_DMA_H
11 #define VIRT_DMA_H
12 
13 #include <linux/dmaengine.h>
14 #include <linux/interrupt.h>
15 
16 #include "dmaengine.h"
17 
18 struct virt_dma_desc {
19 	struct dma_async_tx_descriptor tx;
20 	/* protected by vc.lock */
21 	struct list_head node;
22 };
23 
24 struct virt_dma_chan {
25 	struct dma_chan	chan;
26 	struct tasklet_struct task;
27 	void (*desc_free)(struct virt_dma_desc *);
28 
29 	spinlock_t lock;
30 
31 	/* protected by vc.lock */
32 	struct list_head desc_allocated;
33 	struct list_head desc_submitted;
34 	struct list_head desc_issued;
35 	struct list_head desc_completed;
36 
37 	struct virt_dma_desc *cyclic;
38 	struct virt_dma_desc *vd_terminated;
39 };
40 
41 static inline struct virt_dma_chan *to_virt_chan(struct dma_chan *chan)
42 {
43 	return container_of(chan, struct virt_dma_chan, chan);
44 }
45 
46 void vchan_dma_desc_free_list(struct virt_dma_chan *vc, struct list_head *head);
47 void vchan_init(struct virt_dma_chan *vc, struct dma_device *dmadev);
48 struct virt_dma_desc *vchan_find_desc(struct virt_dma_chan *, dma_cookie_t);
49 extern dma_cookie_t vchan_tx_submit(struct dma_async_tx_descriptor *);
50 extern int vchan_tx_desc_free(struct dma_async_tx_descriptor *);
51 
52 /**
53  * vchan_tx_prep - prepare a descriptor
54  * @vc: virtual channel allocating this descriptor
55  * @vd: virtual descriptor to prepare
56  * @tx_flags: flags argument passed in to prepare function
57  */
58 static inline struct dma_async_tx_descriptor *vchan_tx_prep(struct virt_dma_chan *vc,
59 	struct virt_dma_desc *vd, unsigned long tx_flags)
60 {
61 	unsigned long flags;
62 
63 	dma_async_tx_descriptor_init(&vd->tx, &vc->chan);
64 	vd->tx.flags = tx_flags;
65 	vd->tx.tx_submit = vchan_tx_submit;
66 	vd->tx.desc_free = vchan_tx_desc_free;
67 
68 	spin_lock_irqsave(&vc->lock, flags);
69 	list_add_tail(&vd->node, &vc->desc_allocated);
70 	spin_unlock_irqrestore(&vc->lock, flags);
71 
72 	return &vd->tx;
73 }
74 
75 /**
76  * vchan_issue_pending - move submitted descriptors to issued list
77  * @vc: virtual channel to update
78  *
79  * vc.lock must be held by caller
80  */
81 static inline bool vchan_issue_pending(struct virt_dma_chan *vc)
82 {
83 	list_splice_tail_init(&vc->desc_submitted, &vc->desc_issued);
84 	return !list_empty(&vc->desc_issued);
85 }
86 
87 /**
88  * vchan_cookie_complete - report completion of a descriptor
89  * @vd: virtual descriptor to update
90  *
91  * vc.lock must be held by caller
92  */
93 static inline void vchan_cookie_complete(struct virt_dma_desc *vd)
94 {
95 	struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
96 	dma_cookie_t cookie;
97 
98 	cookie = vd->tx.cookie;
99 	dma_cookie_complete(&vd->tx);
100 	dev_vdbg(vc->chan.device->dev, "txd %p[%x]: marked complete\n",
101 		 vd, cookie);
102 	list_add_tail(&vd->node, &vc->desc_completed);
103 
104 	tasklet_schedule(&vc->task);
105 }
106 
107 /**
108  * vchan_vdesc_fini - Free or reuse a descriptor
109  * @vd: virtual descriptor to free/reuse
110  */
111 static inline void vchan_vdesc_fini(struct virt_dma_desc *vd)
112 {
113 	struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
114 
115 	if (dmaengine_desc_test_reuse(&vd->tx))
116 		list_add(&vd->node, &vc->desc_allocated);
117 	else
118 		vc->desc_free(vd);
119 }
120 
121 /**
122  * vchan_cyclic_callback - report the completion of a period
123  * @vd: virtual descriptor
124  */
125 static inline void vchan_cyclic_callback(struct virt_dma_desc *vd)
126 {
127 	struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
128 
129 	vc->cyclic = vd;
130 	tasklet_schedule(&vc->task);
131 }
132 
133 /**
134  * vchan_terminate_vdesc - Disable pending cyclic callback
135  * @vd: virtual descriptor to be terminated
136  *
137  * vc.lock must be held by caller
138  */
139 static inline void vchan_terminate_vdesc(struct virt_dma_desc *vd)
140 {
141 	struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
142 
143 	/* free up stuck descriptor */
144 	if (vc->vd_terminated)
145 		vchan_vdesc_fini(vc->vd_terminated);
146 
147 	vc->vd_terminated = vd;
148 	if (vc->cyclic == vd)
149 		vc->cyclic = NULL;
150 }
151 
152 /**
153  * vchan_next_desc - peek at the next descriptor to be processed
154  * @vc: virtual channel to obtain descriptor from
155  *
156  * vc.lock must be held by caller
157  */
158 static inline struct virt_dma_desc *vchan_next_desc(struct virt_dma_chan *vc)
159 {
160 	return list_first_entry_or_null(&vc->desc_issued,
161 					struct virt_dma_desc, node);
162 }
163 
164 /**
165  * vchan_get_all_descriptors - obtain all submitted and issued descriptors
166  * @vc: virtual channel to get descriptors from
167  * @head: list of descriptors found
168  *
169  * vc.lock must be held by caller
170  *
171  * Removes all submitted and issued descriptors from internal lists, and
172  * provides a list of all descriptors found
173  */
174 static inline void vchan_get_all_descriptors(struct virt_dma_chan *vc,
175 	struct list_head *head)
176 {
177 	list_splice_tail_init(&vc->desc_allocated, head);
178 	list_splice_tail_init(&vc->desc_submitted, head);
179 	list_splice_tail_init(&vc->desc_issued, head);
180 	list_splice_tail_init(&vc->desc_completed, head);
181 }
182 
183 static inline void vchan_free_chan_resources(struct virt_dma_chan *vc)
184 {
185 	struct virt_dma_desc *vd;
186 	unsigned long flags;
187 	LIST_HEAD(head);
188 
189 	spin_lock_irqsave(&vc->lock, flags);
190 	vchan_get_all_descriptors(vc, &head);
191 	list_for_each_entry(vd, &head, node)
192 		dmaengine_desc_clear_reuse(&vd->tx);
193 	spin_unlock_irqrestore(&vc->lock, flags);
194 
195 	vchan_dma_desc_free_list(vc, &head);
196 }
197 
198 /**
199  * vchan_synchronize() - synchronize callback execution to the current context
200  * @vc: virtual channel to synchronize
201  *
202  * Makes sure that all scheduled or active callbacks have finished running. For
203  * proper operation the caller has to ensure that no new callbacks are scheduled
204  * after the invocation of this function started.
205  * Free up the terminated cyclic descriptor to prevent memory leakage.
206  */
207 static inline void vchan_synchronize(struct virt_dma_chan *vc)
208 {
209 	unsigned long flags;
210 
211 	tasklet_kill(&vc->task);
212 
213 	spin_lock_irqsave(&vc->lock, flags);
214 	if (vc->vd_terminated) {
215 		vchan_vdesc_fini(vc->vd_terminated);
216 		vc->vd_terminated = NULL;
217 	}
218 	spin_unlock_irqrestore(&vc->lock, flags);
219 }
220 
221 #endif
222