dmaengine: coh901318: convert callback to helper function

This is in preperation of moving to a callback that provides results to the
callback for the transaction. The conversion will maintain current behavior
and the driver must convert to new callback mechanism at a later time in
order to receive results.
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Lars-Peter Clausen <lars@metafoo.de>
Cc: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

drivers/dma/coh901318.c

@@ -1888,8 +1888,7 @@ static void dma_tasklet(unsigned long data)
 	struct coh901318_chan *cohc = (struct coh901318_chan *) data;
 	struct coh901318_desc *cohd_fin;
 	unsigned long flags;
-	dma_async_tx_callback callback;
-	void *callback_param;
+	struct dmaengine_desc_callback cb;
 
 	dev_vdbg(COHC_2_DEV(cohc), "[%s] chan_id %d"
 		 " nbr_active_done %ld\n", __func__,
@@ -1904,8 +1903,7 @@ static void dma_tasklet(unsigned long data)
 		goto err;
 
 	/* locate callback to client */
-	callback = cohd_fin->desc.callback;
-	callback_param = cohd_fin->desc.callback_param;
+	dmaengine_desc_get_callback(&cohd_fin->desc, &cb);
 
 	/* sign this job as completed on the channel */
 	dma_cookie_complete(&cohd_fin->desc);
@@ -1920,8 +1918,7 @@ static void dma_tasklet(unsigned long data)
 	spin_unlock_irqrestore(&cohc->lock, flags);
 
 	/* Call the callback when we're done */
-	if (callback)
-		callback(callback_param);
+	dmaengine_desc_callback_invoke(&cb, NULL);
 
 	spin_lock_irqsave(&cohc->lock, flags);