drivers/dma/virt-dma.h

   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         /* protected by vc.lock */
  18         struct list_head node;
  19 };
  20
  21 struct virt_dma_chan {
  22         struct dma_chan chan;
  23         struct tasklet_struct task;
  24         void (*desc_free)(struct virt_dma_desc *);
  25
  26         spinlock_t lock;
  27
  28         /* protected by vc.lock */
  29         struct list_head desc_allocated;
  30         struct list_head desc_submitted;
  31         struct list_head desc_issued;
  32         struct list_head desc_completed;
  33
  34         struct virt_dma_desc *cyclic;
  35         struct virt_dma_desc *vd_terminated;
  36 };
  37
  38 static inline struct virt_dma_chan *to_virt_chan(struct dma_chan *chan)
  39 {
  40         return container_of(chan, struct virt_dma_chan, chan);
  41 }
  42
  43 void vchan_dma_desc_free_list(struct virt_dma_chan *vc, struct list_head *head);
  44 void vchan_init(struct virt_dma_chan *vc, struct dma_device *dmadev);
  45 struct virt_dma_desc *vchan_find_desc(struct virt_dma_chan *, dma_cookie_t);
  46 extern dma_cookie_t vchan_tx_submit(struct dma_async_tx_descriptor *);
  47 extern int vchan_tx_desc_free(struct dma_async_tx_descriptor *);
  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         unsigned long flags;
  59
  60         dma_async_tx_descriptor_init(&vd->tx, &vc->chan);
  61         vd->tx.flags = tx_flags;
  62         vd->tx.tx_submit = vchan_tx_submit;
  63         vd->tx.desc_free = vchan_tx_desc_free;
  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_vdesc_fini - Free or reuse a descriptor
 106  * @vd: virtual descriptor to free/reuse
 107  */
 108 static inline void vchan_vdesc_fini(struct virt_dma_desc *vd)
 109 {
 110         struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
 111
 112         if (dmaengine_desc_test_reuse(&vd->tx))
 113                 list_add(&vd->node, &vc->desc_allocated);
 114         else
 115                 vc->desc_free(vd);
 116 }
 117
 118 /**
 119  * vchan_cyclic_callback - report the completion of a period
 120  * @vd: virtual descriptor
 121  */
 122 static inline void vchan_cyclic_callback(struct virt_dma_desc *vd)
 123 {
 124         struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
 125
 126         vc->cyclic = vd;
 127         tasklet_schedule(&vc->task);
 128 }
 129
 130 /**
 131  * vchan_terminate_vdesc - Disable pending cyclic callback
 132  * @vd: virtual descriptor to be terminated
 133  *
 134  * vc.lock must be held by caller
 135  */
 136 static inline void vchan_terminate_vdesc(struct virt_dma_desc *vd)
 137 {
 138         struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
 139
 140         /* free up stuck descriptor */
 141         if (vc->vd_terminated)
 142                 vchan_vdesc_fini(vc->vd_terminated);
 143
 144         vc->vd_terminated = vd;
 145         if (vc->cyclic == vd)
 146                 vc->cyclic = NULL;
 147 }
 148
 149 /**
 150  * vchan_next_desc - peek at the next descriptor to be processed
 151  * @vc: virtual channel to obtain descriptor from
 152  *
 153  * vc.lock must be held by caller
 154  */
 155 static inline struct virt_dma_desc *vchan_next_desc(struct virt_dma_chan *vc)
 156 {
 157         return list_first_entry_or_null(&vc->desc_issued,
 158                                         struct virt_dma_desc, node);
 159 }
 160
 161 /**
 162  * vchan_get_all_descriptors - obtain all submitted and issued descriptors
 163  * @vc: virtual channel to get descriptors from
 164  * @head: list of descriptors found
 165  *
 166  * vc.lock must be held by caller
 167  *
 168  * Removes all submitted and issued descriptors from internal lists, and
 169  * provides a list of all descriptors found
 170  */
 171 static inline void vchan_get_all_descriptors(struct virt_dma_chan *vc,
 172         struct list_head *head)
 173 {
 174         list_splice_tail_init(&vc->desc_allocated, head);
 175         list_splice_tail_init(&vc->desc_submitted, head);
 176         list_splice_tail_init(&vc->desc_issued, head);
 177         list_splice_tail_init(&vc->desc_completed, head);
 178 }
 179
 180 static inline void vchan_free_chan_resources(struct virt_dma_chan *vc)
 181 {
 182         struct virt_dma_desc *vd;
 183         unsigned long flags;
 184         LIST_HEAD(head);
 185
 186         spin_lock_irqsave(&vc->lock, flags);
 187         vchan_get_all_descriptors(vc, &head);
 188         list_for_each_entry(vd, &head, node)
 189                 dmaengine_desc_clear_reuse(&vd->tx);
 190         spin_unlock_irqrestore(&vc->lock, flags);
 191
 192         vchan_dma_desc_free_list(vc, &head);
 193 }
 194
 195 /**
 196  * vchan_synchronize() - synchronize callback execution to the current context
 197  * @vc: virtual channel to synchronize
 198  *
 199  * Makes sure that all scheduled or active callbacks have finished running. For
 200  * proper operation the caller has to ensure that no new callbacks are scheduled
 201  * after the invocation of this function started.
 202  * Free up the terminated cyclic descriptor to prevent memory leakage.
 203  */
 204 static inline void vchan_synchronize(struct virt_dma_chan *vc)
 205 {
 206         unsigned long flags;
 207
 208         tasklet_kill(&vc->task);
 209
 210         spin_lock_irqsave(&vc->lock, flags);
 211         if (vc->vd_terminated) {
 212                 vchan_vdesc_fini(vc->vd_terminated);
 213                 vc->vd_terminated = NULL;
 214         }
 215         spin_unlock_irqrestore(&vc->lock, flags);
 216 }
 217
 218 #endif