As the DMA controller on Sophgo CV1800 series SoC only has 8 channels,
the SoC provides a dma multiplexer to reuse the DMA channel. However,
the dma multiplexer also controls the DMA interrupt multiplexer, which
means that the dma multiplexer needs to know the channel number.

Allow the driver to use DMA phandle args as the channel number, so the
DMA multiplexer can route the DMA interrupt correctly.

Signed-off-by: Inochi Amaoto <inochiama@gmail.com>
---
 .../dma/dw-axi-dmac/dw-axi-dmac-platform.c    | 26 ++++++++++++++++---
 drivers/dma/dw-axi-dmac/dw-axi-dmac.h         |  1 +
 2 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
index b23536645ff7..829aa6c05b5c 100644
--- a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
+++ b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
@@ -7,6 +7,7 @@
  * Author: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
  */
 
+#include "linux/stddef.h"
 #include <linux/bitops.h>
 #include <linux/delay.h>
 #include <linux/device.h>
@@ -50,6 +51,7 @@
 #define AXI_DMA_FLAG_HAS_APB_REGS	BIT(0)
 #define AXI_DMA_FLAG_HAS_RESETS		BIT(1)
 #define AXI_DMA_FLAG_USE_CFG2		BIT(2)
+#define AXI_DMA_FLAG_HANDSHAKE_AS_CHAN	BIT(3)
 
 static inline void
 axi_dma_iowrite32(struct axi_dma_chip *chip, u32 reg, u32 val)
@@ -1360,16 +1362,27 @@ static int __maybe_unused axi_dma_runtime_resume(struct device *dev)
 static struct dma_chan *dw_axi_dma_of_xlate(struct of_phandle_args *dma_spec,
 					    struct of_dma *ofdma)
 {
+	unsigned int handshake = dma_spec->args[0];
 	struct dw_axi_dma *dw = ofdma->of_dma_data;
-	struct axi_dma_chan *chan;
+	struct axi_dma_chan *chan = NULL;
 	struct dma_chan *dchan;
 
-	dchan = dma_get_any_slave_channel(&dw->dma);
+	if (dw->hdata->use_handshake_as_channel_number) {
+		if (handshake >= dw->hdata->nr_channels)
+			return NULL;
+
+		chan = &dw->chan[handshake];
+		dchan = dma_get_slave_channel(&chan->vc.chan);
+	} else {
+		dchan = dma_get_any_slave_channel(&dw->dma);
+	}
+
 	if (!dchan)
 		return NULL;
 
-	chan = dchan_to_axi_dma_chan(dchan);
-	chan->hw_handshake_num = dma_spec->args[0];
+	if (!chan)
+		chan = dchan_to_axi_dma_chan(dchan);
+	chan->hw_handshake_num = handshake;
 	return dchan;
 }
 
@@ -1508,6 +1521,8 @@ static int dw_probe(struct platform_device *pdev)
 			return ret;
 	}
 
+	chip->dw->hdata->use_handshake_as_channel_number = !!(flags & AXI_DMA_FLAG_HANDSHAKE_AS_CHAN);
+
 	chip->dw->hdata->use_cfg2 = !!(flags & AXI_DMA_FLAG_USE_CFG2);
 
 	chip->core_clk = devm_clk_get(chip->dev, "core-clk");
@@ -1663,6 +1678,9 @@ static const struct of_device_id dw_dma_of_id_table[] = {
 	}, {
 		.compatible = "intel,kmb-axi-dma",
 		.data = (void *)AXI_DMA_FLAG_HAS_APB_REGS,
+	}, {
+		.compatible = "sophgo,cv1800b-axi-dma",
+		.data = (void *)AXI_DMA_FLAG_HANDSHAKE_AS_CHAN,
 	}, {
 		.compatible = "starfive,jh7110-axi-dma",
 		.data = (void *)(AXI_DMA_FLAG_HAS_RESETS | AXI_DMA_FLAG_USE_CFG2),
diff --git a/drivers/dma/dw-axi-dmac/dw-axi-dmac.h b/drivers/dma/dw-axi-dmac/dw-axi-dmac.h
index b842e6a8d90d..67cc199e24d1 100644
--- a/drivers/dma/dw-axi-dmac/dw-axi-dmac.h
+++ b/drivers/dma/dw-axi-dmac/dw-axi-dmac.h
@@ -34,6 +34,7 @@ struct dw_axi_dma_hcfg {
 	bool	reg_map_8_channels;
 	bool	restrict_axi_burst_len;
 	bool	use_cfg2;
+	bool	use_handshake_as_channel_number;
 };
 
 struct axi_dma_chan {
-- 
2.52.0