2 * Virtual DMA channel support for DMAengine
4 * Copyright (C) 2012 Russell King
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.
13 #include <linux/dmaengine.h>
14 #include <linux/interrupt.h>
16 #include "dmaengine.h"
18 struct virt_dma_desc {
19 struct dma_async_tx_descriptor tx;
20 /* protected by vc.lock */
21 struct list_head node;
24 struct virt_dma_chan {
26 struct tasklet_struct task;
27 void (*desc_free)(struct virt_dma_desc *);
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;
37 struct virt_dma_desc *cyclic;
40 static inline struct virt_dma_chan *to_virt_chan(struct dma_chan *chan)
42 return container_of(chan, struct virt_dma_chan, chan);
45 void vchan_dma_desc_free_list(struct virt_dma_chan *vc, struct list_head *head);
46 void vchan_init(struct virt_dma_chan *vc, struct dma_device *dmadev);
47 struct virt_dma_desc *vchan_find_desc(struct virt_dma_chan *, dma_cookie_t);
50 * vchan_tx_prep - prepare a descriptor
51 * vc: virtual channel allocating this descriptor
52 * vd: virtual descriptor to prepare
53 * tx_flags: flags argument passed in to prepare function
55 static inline struct dma_async_tx_descriptor *vchan_tx_prep(struct virt_dma_chan *vc,
56 struct virt_dma_desc *vd, unsigned long tx_flags)
58 extern dma_cookie_t vchan_tx_submit(struct dma_async_tx_descriptor *);
61 dma_async_tx_descriptor_init(&vd->tx, &vc->chan);
62 vd->tx.flags = tx_flags;
63 vd->tx.tx_submit = vchan_tx_submit;
65 spin_lock_irqsave(&vc->lock, flags);
66 list_add_tail(&vd->node, &vc->desc_allocated);
67 spin_unlock_irqrestore(&vc->lock, flags);
73 * vchan_issue_pending - move submitted descriptors to issued list
74 * vc: virtual channel to update
76 * vc.lock must be held by caller
78 static inline bool vchan_issue_pending(struct virt_dma_chan *vc)
80 list_splice_tail_init(&vc->desc_submitted, &vc->desc_issued);
81 return !list_empty(&vc->desc_issued);
85 * vchan_cookie_complete - report completion of a descriptor
86 * vd: virtual descriptor to update
88 * vc.lock must be held by caller
90 static inline void vchan_cookie_complete(struct virt_dma_desc *vd)
92 struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
95 cookie = vd->tx.cookie;
96 dma_cookie_complete(&vd->tx);
97 dev_vdbg(vc->chan.device->dev, "txd %p[%x]: marked complete\n",
99 list_add_tail(&vd->node, &vc->desc_completed);
101 tasklet_schedule(&vc->task);
105 * vchan_cyclic_callback - report the completion of a period
106 * vd: virtual descriptor
108 static inline void vchan_cyclic_callback(struct virt_dma_desc *vd)
110 struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
113 tasklet_schedule(&vc->task);
117 * vchan_next_desc - peek at the next descriptor to be processed
118 * vc: virtual channel to obtain descriptor from
120 * vc.lock must be held by caller
122 static inline struct virt_dma_desc *vchan_next_desc(struct virt_dma_chan *vc)
124 if (list_empty(&vc->desc_issued))
127 return list_first_entry(&vc->desc_issued, struct virt_dma_desc, node);
131 * vchan_get_all_descriptors - obtain all allocated, submitted and issued
133 * vc: virtual channel to get descriptors from
134 * head: list of descriptors found
136 * vc.lock must be held by caller
138 * Removes all submitted and issued descriptors from internal lists, and
139 * provides a list of all descriptors found
141 static inline void vchan_get_all_descriptors(struct virt_dma_chan *vc,
142 struct list_head *head)
144 list_splice_tail_init(&vc->desc_allocated, head);
145 list_splice_tail_init(&vc->desc_submitted, head);
146 list_splice_tail_init(&vc->desc_issued, head);
147 list_splice_tail_init(&vc->desc_completed, head);
150 static inline void vchan_free_chan_resources(struct virt_dma_chan *vc)
152 struct virt_dma_desc *vd;
156 spin_lock_irqsave(&vc->lock, flags);
157 vchan_get_all_descriptors(vc, &head);
158 list_for_each_entry(vd, &head, node)
159 async_tx_clear_ack(&vd->tx);
160 spin_unlock_irqrestore(&vc->lock, flags);
162 vchan_dma_desc_free_list(vc, &head);