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 };
  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         extern int vchan_tx_desc_free(struct dma_async_tx_descriptor *);
  60         unsigned long flags;
  61
  62         dma_async_tx_descriptor_init(&vd->tx, &vc->chan);
  63         vd->tx.flags = tx_flags;
  64         vd->tx.tx_submit = vchan_tx_submit;
  65         vd->tx.desc_free = vchan_tx_desc_free;
  66
  67         spin_lock_irqsave(&vc->lock, flags);
  68         list_add_tail(&vd->node, &vc->desc_allocated);
  69         spin_unlock_irqrestore(&vc->lock, flags);
  70
  71         return &vd->tx;
  72 }
  73
  74 /**
  75  * vchan_issue_pending - move submitted descriptors to issued list
  76  * @vc: virtual channel to update
  77  *
  78  * vc.lock must be held by caller
  79  */
  80 static inline bool vchan_issue_pending(struct virt_dma_chan *vc)
  81 {
  82         list_splice_tail_init(&vc->desc_submitted, &vc->desc_issued);
  83         return !list_empty(&vc->desc_issued);
  84 }
  85
  86 /**
  87  * vchan_cookie_complete - report completion of a descriptor
  88  * @vd: virtual descriptor to update
  89  *
  90  * vc.lock must be held by caller
  91  */
  92 static inline void vchan_cookie_complete(struct virt_dma_desc *vd)
  93 {
  94         struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
  95         dma_cookie_t cookie;
  96
  97         cookie = vd->tx.cookie;
  98         dma_cookie_complete(&vd->tx);
  99         dev_vdbg(vc->chan.device->dev, "txd %p[%x]: marked complete\n",
 100                  vd, cookie);
 101         list_add_tail(&vd->node, &vc->desc_completed);
 102
 103         tasklet_schedule(&vc->task);
 104 }
 105
 106 /**
 107  * vchan_cyclic_callback - report the completion of a period
 108  * @vd: virtual descriptor
 109  */
 110 static inline void vchan_cyclic_callback(struct virt_dma_desc *vd)
 111 {
 112         struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
 113
 114         vc->cyclic = vd;
 115         tasklet_schedule(&vc->task);
 116 }
 117
 118 /**
 119  * vchan_next_desc - peek at the next descriptor to be processed
 120  * @vc: virtual channel to obtain descriptor from
 121  *
 122  * vc.lock must be held by caller
 123  */
 124 static inline struct virt_dma_desc *vchan_next_desc(struct virt_dma_chan *vc)
 125 {
 126         if (list_empty(&vc->desc_issued))
 127                 return NULL;
 128
 129         return list_first_entry(&vc->desc_issued, struct virt_dma_desc, node);
 130 }
 131
 132 /**
 133  * vchan_get_all_descriptors - obtain all submitted and issued descriptors
 134  * @vc: virtual channel to get descriptors from
 135  * @head: list of descriptors found
 136  *
 137  * vc.lock must be held by caller
 138  *
 139  * Removes all submitted and issued descriptors from internal lists, and
 140  * provides a list of all descriptors found
 141  */
 142 static inline void vchan_get_all_descriptors(struct virt_dma_chan *vc,
 143         struct list_head *head)
 144 {
 145         list_splice_tail_init(&vc->desc_allocated, head);
 146         list_splice_tail_init(&vc->desc_submitted, head);
 147         list_splice_tail_init(&vc->desc_issued, head);
 148         list_splice_tail_init(&vc->desc_completed, head);
 149 }
 150
 151 static inline void vchan_free_chan_resources(struct virt_dma_chan *vc)
 152 {
 153         struct virt_dma_desc *vd;
 154         unsigned long flags;
 155         LIST_HEAD(head);
 156
 157         spin_lock_irqsave(&vc->lock, flags);
 158         vchan_get_all_descriptors(vc, &head);
 159         list_for_each_entry(vd, &head, node)
 160                 dmaengine_desc_clear_reuse(&vd->tx);
 161         spin_unlock_irqrestore(&vc->lock, flags);
 162
 163         vchan_dma_desc_free_list(vc, &head);
 164 }
 165
 166 /**
 167  * vchan_synchronize() - synchronize callback execution to the current context
 168  * @vc: virtual channel to synchronize
 169  *
 170  * Makes sure that all scheduled or active callbacks have finished running. For
 171  * proper operation the caller has to ensure that no new callbacks are scheduled
 172  * after the invocation of this function started.
 173  */
 174 static inline void vchan_synchronize(struct virt_dma_chan *vc)
 175 {
 176         tasklet_kill(&vc->task);
 177 }
 178
 179 #endif