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 }; 39 40 static inline struct virt_dma_chan *to_virt_chan(struct dma_chan *chan) 41 { 42 return container_of(chan, struct virt_dma_chan, chan); 43 } 44 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); 48 49 /** 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 54 */ 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) 57 { 58 extern dma_cookie_t vchan_tx_submit(struct dma_async_tx_descriptor *); 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 65 spin_lock_irqsave(&vc->lock, flags); 66 list_add_tail(&vd->node, &vc->desc_allocated); 67 spin_unlock_irqrestore(&vc->lock, flags); 68 69 return &vd->tx; 70 } 71 72 /** 73 * vchan_issue_pending - move submitted descriptors to issued list 74 * vc: virtual channel to update 75 * 76 * vc.lock must be held by caller 77 */ 78 static inline bool vchan_issue_pending(struct virt_dma_chan *vc) 79 { 80 list_splice_tail_init(&vc->desc_submitted, &vc->desc_issued); 81 return !list_empty(&vc->desc_issued); 82 } 83 84 /** 85 * vchan_cookie_complete - report completion of a descriptor 86 * vd: virtual descriptor to update 87 * 88 * vc.lock must be held by caller 89 */ 90 static inline void vchan_cookie_complete(struct virt_dma_desc *vd) 91 { 92 struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan); 93 dma_cookie_t cookie; 94 95 cookie = vd->tx.cookie; 96 dma_cookie_complete(&vd->tx); 97 dev_vdbg(vc->chan.device->dev, "txd %p[%x]: marked complete\n", 98 vd, cookie); 99 list_add_tail(&vd->node, &vc->desc_completed); 100 101 tasklet_schedule(&vc->task); 102 } 103 104 /** 105 * vchan_cyclic_callback - report the completion of a period 106 * vd: virtual descriptor 107 */ 108 static inline void vchan_cyclic_callback(struct virt_dma_desc *vd) 109 { 110 struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan); 111 112 vc->cyclic = vd; 113 tasklet_schedule(&vc->task); 114 } 115 116 /** 117 * vchan_next_desc - peek at the next descriptor to be processed 118 * vc: virtual channel to obtain descriptor from 119 * 120 * vc.lock must be held by caller 121 */ 122 static inline struct virt_dma_desc *vchan_next_desc(struct virt_dma_chan *vc) 123 { 124 if (list_empty(&vc->desc_issued)) 125 return NULL; 126 127 return list_first_entry(&vc->desc_issued, struct virt_dma_desc, node); 128 } 129 130 /** 131 * vchan_get_all_descriptors - obtain all allocated, submitted and issued 132 * descriptors 133 * vc: virtual channel to get descriptors from 134 * head: list of descriptors found 135 * 136 * vc.lock must be held by caller 137 * 138 * Removes all submitted and issued descriptors from internal lists, and 139 * provides a list of all descriptors found 140 */ 141 static inline void vchan_get_all_descriptors(struct virt_dma_chan *vc, 142 struct list_head *head) 143 { 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); 148 } 149 150 static inline void vchan_free_chan_resources(struct virt_dma_chan *vc) 151 { 152 struct virt_dma_desc *vd; 153 unsigned long flags; 154 LIST_HEAD(head); 155 156 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); 161 162 vchan_dma_desc_free_list(vc, &head); 163 } 164 165 #endif 166