dmaengine: use idr for registering dma device numbers

This brings some predictability to dma device numbers, i.e. an rmmod/insmod
cycle may now result in /sys/class/dma/dma0chan0 being restored rather than
/sys/class/dma/dma1chan0 appearing.

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

1 files changed, 4 insertions, 0 deletions

diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index d6b6bff355f4..64dea2ab326c 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -140,10 +140,14 @@ struct dma_chan {
  * struct dma_chan_dev - relate sysfs device node to backing channel device
  * @chan - driver channel device
  * @device - sysfs device
+ * @dev_id - parent dma_device dev_id
+ * @idr_ref - reference count to gate release of dma_device dev_id
  */
 struct dma_chan_dev {
         struct dma_chan *chan;
         struct device device;
+        int dev_id;
+        atomic_t *idr_ref;
 };
 
 static inline const char *dma_chan_name(struct dma_chan *chan)