xref: /openbmc/linux/drivers/dma/virt-dma.h (revision 9f91e6bf)
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 	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  */
vchan_cookie_complete(struct virt_dma_desc * vd)94 static 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  */
vchan_vdesc_fini(struct virt_dma_desc * vd)112 static 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  */
vchan_cyclic_callback(struct virt_dma_desc * vd)131 static 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  */
vchan_terminate_vdesc(struct virt_dma_desc * vd)145 static 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  */
vchan_next_desc(struct virt_dma_chan * vc)161 static 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  */
vchan_get_all_descriptors(struct virt_dma_chan * vc,struct list_head * head)177 static 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 
vchan_free_chan_resources(struct virt_dma_chan * vc)187 static 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  */
vchan_synchronize(struct virt_dma_chan * vc)211 static 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