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