drivers/dma/dmaengine.h

   1 /*
   2  * The contents of this file are private to DMA engine drivers, and is not
   3  * part of the API to be used by DMA engine users.
   4  */
   5 #ifndef DMAENGINE_H
   6 #define DMAENGINE_H
   7
   8 #include <linux/bug.h>
   9 #include <linux/dmaengine.h>
  10
  11 /**
  12  * dma_cookie_init - initialize the cookies for a DMA channel
  13  * @chan: dma channel to initialize
  14  */
  15 static inline void dma_cookie_init(struct dma_chan *chan)
  16 {
  17         chan->cookie = DMA_MIN_COOKIE;
  18         chan->completed_cookie = DMA_MIN_COOKIE;
  19 }
  20
  21 /**
  22  * dma_cookie_assign - assign a DMA engine cookie to the descriptor
  23  * @tx: descriptor needing cookie
  24  *
  25  * Assign a unique non-zero per-channel cookie to the descriptor.
  26  * Note: caller is expected to hold a lock to prevent concurrency.
  27  */
  28 static inline dma_cookie_t dma_cookie_assign(struct dma_async_tx_descriptor *tx)
  29 {
  30         struct dma_chan *chan = tx->chan;
  31         dma_cookie_t cookie;
  32
  33         cookie = chan->cookie + 1;
  34         if (cookie < DMA_MIN_COOKIE)
  35                 cookie = DMA_MIN_COOKIE;
  36         tx->cookie = chan->cookie = cookie;
  37
  38         return cookie;
  39 }
  40
  41 /**
  42  * dma_cookie_complete - complete a descriptor
  43  * @tx: descriptor to complete
  44  *
  45  * Mark this descriptor complete by updating the channels completed
  46  * cookie marker.  Zero the descriptors cookie to prevent accidental
  47  * repeated completions.
  48  *
  49  * Note: caller is expected to hold a lock to prevent concurrency.
  50  */
  51 static inline void dma_cookie_complete(struct dma_async_tx_descriptor *tx)
  52 {
  53         BUG_ON(tx->cookie < DMA_MIN_COOKIE);
  54         tx->chan->completed_cookie = tx->cookie;
  55         tx->cookie = 0;
  56 }
  57
  58 /**
  59  * dma_cookie_status - report cookie status
  60  * @chan: dma channel
  61  * @cookie: cookie we are interested in
  62  * @state: dma_tx_state structure to return last/used cookies
  63  *
  64  * Report the status of the cookie, filling in the state structure if
  65  * non-NULL.  No locking is required.
  66  */
  67 static inline enum dma_status dma_cookie_status(struct dma_chan *chan,
  68         dma_cookie_t cookie, struct dma_tx_state *state)
  69 {
  70         dma_cookie_t used, complete;
  71
  72         used = chan->cookie;
  73         complete = chan->completed_cookie;
  74         barrier();
  75         if (state) {
  76                 state->last = complete;
  77                 state->used = used;
  78                 state->residue = 0;
  79         }
  80         return dma_async_is_complete(cookie, complete, used);
  81 }
  82
  83 static inline void dma_set_residue(struct dma_tx_state *state, u32 residue)
  84 {
  85         if (state)
  86                 state->residue = residue;
  87 }
  88
  89 #endif