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         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
  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  */
  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  */
  82 static inline bool vchan_issue_pending(struct virt_dma_chan *vc)
  83 {
  84         lockdep_assert_held(&vc->lock);
  85
  86         list_splice_tail_init(&vc->desc_submitted, &vc->desc_issued);
  87         return !list_empty(&vc->desc_issued);
  88 }
  89
  90 /**
  91  * vchan_cookie_complete - report completion of a descriptor
  92  * @vd: virtual descriptor to update
  93  *
  94  * vc.lock must be held by caller
  95  */
  96 static inline void vchan_cookie_complete(struct virt_dma_desc *vd)
  97 {
  98         struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
  99         dma_cookie_t cookie;
 100
 101         lockdep_assert_held(&vc->lock);
 102
 103         cookie = vd->tx.cookie;
 104         dma_cookie_complete(&vd->tx);
 105         dev_vdbg(vc->chan.device->dev, "txd %p[%x]: marked complete\n",
 106                  vd, cookie);
 107         list_add_tail(&vd->node, &vc->desc_completed);
 108
 109         tasklet_schedule(&vc->task);
 110 }
 111
 112 /**
 113  * vchan_vdesc_fini - Free or reuse a descriptor
 114  * @vd: virtual descriptor to free/reuse
 115  */
 116 static inline void vchan_vdesc_fini(struct virt_dma_desc *vd)
 117 {
 118         struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
 119
 120         if (dmaengine_desc_test_reuse(&vd->tx)) {
 121                 unsigned long flags;
 122
 123                 spin_lock_irqsave(&vc->lock, flags);
 124                 list_add(&vd->node, &vc->desc_allocated);
 125                 spin_unlock_irqrestore(&vc->lock, flags);
 126         } else {
 127                 vc->desc_free(vd);
 128         }
 129 }
 130
 131 /**
 132  * vchan_cyclic_callback - report the completion of a period
 133  * @vd: virtual descriptor
 134  */
 135 static inline void vchan_cyclic_callback(struct virt_dma_desc *vd)
 136 {
 137         struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
 138
 139         vc->cyclic = vd;
 140         tasklet_schedule(&vc->task);
 141 }
 142
 143 /**
 144  * vchan_terminate_vdesc - Disable pending cyclic callback
 145  * @vd: virtual descriptor to be terminated
 146  *
 147  * vc.lock must be held by caller
 148  */
 149 static inline void vchan_terminate_vdesc(struct virt_dma_desc *vd)
 150 {
 151         struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
 152
 153         lockdep_assert_held(&vc->lock);
 154
 155         list_add_tail(&vd->node, &vc->desc_terminated);
 156
 157         if (vc->cyclic == vd)
 158                 vc->cyclic = NULL;
 159 }
 160
 161 /**
 162  * vchan_next_desc - peek at the next descriptor to be processed
 163  * @vc: virtual channel to obtain descriptor from
 164  *
 165  * vc.lock must be held by caller
 166  */
 167 static inline struct virt_dma_desc *vchan_next_desc(struct virt_dma_chan *vc)
 168 {
 169         lockdep_assert_held(&vc->lock);
 170
 171         return list_first_entry_or_null(&vc->desc_issued,
 172                                         struct virt_dma_desc, node);
 173 }
 174
 175 /**
 176  * vchan_get_all_descriptors - obtain all submitted and issued descriptors
 177  * @vc: virtual channel to get descriptors from
 178  * @head: list of descriptors found
 179  *
 180  * vc.lock must be held by caller
 181  *
 182  * Removes all submitted and issued descriptors from internal lists, and
 183  * provides a list of all descriptors found
 184  */
 185 static inline void vchan_get_all_descriptors(struct virt_dma_chan *vc,
 186         struct list_head *head)
 187 {
 188         lockdep_assert_held(&vc->lock);
 189
 190         list_splice_tail_init(&vc->desc_allocated, head);
 191         list_splice_tail_init(&vc->desc_submitted, head);
 192         list_splice_tail_init(&vc->desc_issued, head);
 193         list_splice_tail_init(&vc->desc_completed, head);
 194         list_splice_tail_init(&vc->desc_terminated, head);
 195 }
 196
 197 static inline void vchan_free_chan_resources(struct virt_dma_chan *vc)
 198 {
 199         struct virt_dma_desc *vd;
 200         unsigned long flags;
 201         LIST_HEAD(head);
 202
 203         spin_lock_irqsave(&vc->lock, flags);
 204         vchan_get_all_descriptors(vc, &head);
 205         list_for_each_entry(vd, &head, node)
 206                 dmaengine_desc_clear_reuse(&vd->tx);
 207         spin_unlock_irqrestore(&vc->lock, flags);
 208
 209         vchan_dma_desc_free_list(vc, &head);
 210 }
 211
 212 /**
 213  * vchan_synchronize() - synchronize callback execution to the current context
 214  * @vc: virtual channel to synchronize
 215  *
 216  * Makes sure that all scheduled or active callbacks have finished running. For
 217  * proper operation the caller has to ensure that no new callbacks are scheduled
 218  * after the invocation of this function started.
 219  * Free up the terminated cyclic descriptor to prevent memory leakage.
 220  */
 221 static inline void vchan_synchronize(struct virt_dma_chan *vc)
 222 {
 223         LIST_HEAD(head);
 224         unsigned long flags;
 225
 226         tasklet_kill(&vc->task);
 227
 228         spin_lock_irqsave(&vc->lock, flags);
 229
 230         list_splice_tail_init(&vc->desc_terminated, &head);
 231
 232         spin_unlock_irqrestore(&vc->lock, flags);
 233
 234         vchan_dma_desc_free_list(vc, &head);
 235 }
 236
 237 #endif