[PATCH 3/3] dmaengine: sh: rz-dmac: Add device_pause() callback

[Biju Das <biju.das.jz@xxxxxxxxxxxxxx>]

The device_pause() callback is needed for serial DMA (RZ/G2L
SCIFA). Add support for device_pause() callback.

Based on a patch in the BSP by Long Luu
<long.luu.ur@xxxxxxxxxxx>

Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
---
 drivers/dma/sh/rz-dmac.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/drivers/dma/sh/rz-dmac.c b/drivers/dma/sh/rz-dmac.c
index 3625925d9f9f..a0cfb8f75534 100644
--- a/drivers/dma/sh/rz-dmac.c
+++ b/drivers/dma/sh/rz-dmac.c
@@ -822,6 +822,25 @@ static enum dma_status rz_dmac_tx_status(struct dma_chan *chan,
 	return status;
 }
 
+static int rz_dmac_device_pause(struct dma_chan *chan)
+{
+	struct rz_dmac_chan *channel = to_rz_dmac_chan(chan);
+	struct rz_dmac *dmac = to_rz_dmac(chan->device);
+	unsigned int i;
+	u32 chstat;
+
+	for (i = 0; i < 1024; i++) {
+		chstat = rz_dmac_ch_readl(channel, CHSTAT, 1);
+		if (!(chstat & CHSTAT_EN))
+			break;
+		udelay(1);
+	}
+
+	rz_dmac_set_dmars_register(dmac, channel->index, 0);
+
+	return 0;
+}
+
 /*
  * -----------------------------------------------------------------------------
  * IRQ handling
@@ -1111,6 +1130,7 @@ static int rz_dmac_probe(struct platform_device *pdev)
 	engine->device_terminate_all = rz_dmac_terminate_all;
 	engine->device_issue_pending = rz_dmac_issue_pending;
 	engine->device_synchronize = rz_dmac_device_synchronize;
+	engine->device_pause = rz_dmac_device_pause;
 
 	engine->copy_align = DMAENGINE_ALIGN_1_BYTE;
 	dma_set_max_seg_size(engine->dev, U32_MAX);
-- 
2.25.1