dmaengine: ack to flags: make use of the unused bits in the 'ack' field

'ack' is currently a simple integer that flags whether or not a client is done
touching fields in the given descriptor.  It is effectively just a single bit
of information.  Converting this to a flags parameter allows the other bits to
be put to use to control completion actions, like dma-unmap, and capture
results, like xor-zero-sum == 0.

Changes are one of:
1/ convert all open-coded ->ack manipulations to use async_tx_ack
   and async_tx_test_ack.
2/ set the ack bit at prep time where possible
3/ make drivers store the flags at prep time
4/ add flags to the device_prep_dma_interrupt prototype

Acked-by: Maciej Sosnowski <maciej.sosnowski@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 18 insertions, 7 deletions

diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index cd34df78c6aa..b4d84ed6187d 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -95,12 +95,17 @@ enum dma_transaction_type {
 #define DMA_TX_TYPE_END (DMA_INTERRUPT + 1)
 
 /**
- * enum dma_prep_flags - DMA flags to augment operation preparation
+ * enum dma_ctrl_flags - DMA flags to augment operation preparation,
+ *      control completion, and communicate status.
  * @DMA_PREP_INTERRUPT - trigger an interrupt (callback) upon completion of
  *      this transaction
+ * @DMA_CTRL_ACK - the descriptor cannot be reused until the client
+ *      acknowledges receipt, i.e. has has a chance to establish any
+ *      dependency chains
  */
-enum dma_prep_flags {
+enum dma_ctrl_flags {
         DMA_PREP_INTERRUPT = (1 << 0),
+        DMA_CTRL_ACK = (1 << 1),
 };
 
 /**
@@ -211,8 +216,8 @@ typedef void (*dma_async_tx_callback)(void *dma_async_param);
  * ---dma generic offload fields---
  * @cookie: tracking cookie for this transaction, set to -EBUSY if
  *      this tx is sitting on a dependency list
- * @ack: the descriptor can not be reused until the client acknowledges
- *      receipt, i.e. has has a chance to establish any dependency chains
+ * @flags: flags to augment operation preparation, control completion, and
+ *      communicate status
  * @phys: physical address of the descriptor
  * @tx_list: driver common field for operations that require multiple
  *      descriptors
@@ -227,7 +232,7 @@ typedef void (*dma_async_tx_callback)(void *dma_async_param);
  */
 struct dma_async_tx_descriptor {
         dma_cookie_t cookie;
-        int ack;
+        enum dma_ctrl_flags flags; /* not a 'long' to pack with cookie */
         dma_addr_t phys;
         struct list_head tx_list;
         struct dma_chan *chan;
@@ -290,7 +295,7 @@ struct dma_device {
                 struct dma_chan *chan, dma_addr_t dest, int value, size_t len,
                 unsigned long flags);
         struct dma_async_tx_descriptor *(*device_prep_dma_interrupt)(
-                struct dma_chan *chan);
+                struct dma_chan *chan, unsigned long flags);
 
         enum dma_status (*device_is_tx_complete)(struct dma_chan *chan,
                         dma_cookie_t cookie, dma_cookie_t *last,
@@ -316,7 +321,13 @@ void dma_async_tx_descriptor_init(struct dma_async_tx_descriptor *tx,
 static inline void
 async_tx_ack(struct dma_async_tx_descriptor *tx)
 {
-        tx->ack = 1;
+        tx->flags |= DMA_CTRL_ACK;
+}
+
+static inline int
+async_tx_test_ack(struct dma_async_tx_descriptor *tx)
+{
+        return tx->flags & DMA_CTRL_ACK;
 }
 
 #define first_dma_cap(mask) __first_dma_cap(&(mask))