[PATCH v2 1/3] dmaengine: dw-edma: Implement device_synchronize() callback

[Manivannan Sadhasivam]

device_synchronize() callback is required by the client drivers to ensure
all the DMA operations are completed so that they can free the memory
associated with the complete callbacks.

So implement this callback by first making sure that all the in-flight DMA
operations are completed and then call vchan_synchronize() to drain the
DMA tasklet.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxxxxxxxx>
---
 drivers/dma/dw-edma/dw-edma-core.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-edma-core.c
index c2feb3adc79f..df0d1a946ed0 100644
--- a/drivers/dma/dw-edma/dw-edma-core.c
+++ b/drivers/dma/dw-edma/dw-edma-core.c
@@ -12,6 +12,7 @@
 #include <linux/dmaengine.h>
 #include <linux/err.h>
 #include <linux/interrupt.h>
+#include <linux/iopoll.h>
 #include <linux/irq.h>
 #include <linux/dma/edma.h>
 #include <linux/dma-mapping.h>
@@ -331,6 +332,20 @@ static int dw_edma_device_terminate_all(struct dma_chan *dchan)
 	return err;
 }
 
+static void dw_edma_device_synchronize(struct dma_chan *dchan)
+{
+	struct dw_edma_chan *chan = dchan2dw_edma_chan(dchan);
+
+	/*
+	 * Make sure all the in-flight DMA operations are completed before
+	 * draining the tasklet using vchan_synchronize().
+	 */
+	read_poll_timeout(READ_ONCE, chan->status, chan->status != EDMA_ST_BUSY,
+			  10, 0, false, chan->status);
+
+	vchan_synchronize(&chan->vc);
+}
+
 static void dw_edma_device_issue_pending(struct dma_chan *dchan)
 {
 	struct dw_edma_chan *chan = dchan2dw_edma_chan(dchan);
@@ -968,6 +983,7 @@ static int dw_edma_channel_setup(struct dw_edma *dw, u32 wr_alloc, u32 rd_alloc)
 	dma->device_pause = dw_edma_device_pause;
 	dma->device_resume = dw_edma_device_resume;
 	dma->device_terminate_all = dw_edma_device_terminate_all;
+	dma->device_synchronize = dw_edma_device_synchronize;
 	dma->device_issue_pending = dw_edma_device_issue_pending;
 	dma->device_tx_status = dw_edma_device_tx_status;
 	dma->device_prep_slave_sg = dw_edma_device_prep_slave_sg;

-- 
2.43.0