drivers/dma/virt-dma.h

   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