dmaengine: dw-axi-dmac: Support of_dma_controller_register()

Add support for of_dma_controller_register() so that DMA clients
can pass in device handshake number to the AxiDMA driver.

DMA clients shall code the device handshake number in the Device tree.
When DMA activities are needed, DMA clients shall invoke OF helper
function to pass in the device handshake number to the AxiDMA.

Without register to the of_dma_controller_register(), data transfer
between memory to device and device to memory operations would failed.
Signed-off-by: Sia Jee Heng <jee.heng.sia@intel.com>
Tested-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Link: https://lore.kernel.org/r/20210125013255.25799-9-jee.heng.sia@intel.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c

@@ -20,6 +20,7 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/of_dma.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
 #include <linux/property.h>
@@ -1044,6 +1045,22 @@ static int __maybe_unused axi_dma_runtime_resume(struct device *dev)
 	return axi_dma_resume(chip);
 }
 
+static struct dma_chan *dw_axi_dma_of_xlate(struct of_phandle_args *dma_spec,
+					    struct of_dma *ofdma)
+{
+	struct dw_axi_dma *dw = ofdma->of_dma_data;
+	struct axi_dma_chan *chan;
+	struct dma_chan *dchan;
+
+	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];
+	return dchan;
+}
+
 static int parse_device_properties(struct axi_dma_chip *chip)
 {
 	struct device *dev = chip->dev;
@@ -1233,6 +1250,13 @@ static int dw_probe(struct platform_device *pdev)
 	if (ret)
 		goto err_pm_disable;
 
+	/* Register with OF helpers for DMA lookups */
+	ret = of_dma_controller_register(pdev->dev.of_node,
+					 dw_axi_dma_of_xlate, dw);
+	if (ret < 0)
+		dev_warn(&pdev->dev,
+			 "Failed to register OF DMA controller, fallback to MEM_TO_MEM mode\n");
+
 	dev_info(chip->dev, "DesignWare AXI DMA Controller, %d channels\n",
 		 dw->hdata->nr_channels);
 
@@ -1266,6 +1290,8 @@ static int dw_remove(struct platform_device *pdev)
 
 	devm_free_irq(chip->dev, chip->irq, chip);
 
+	of_dma_controller_free(chip->dev->of_node);
+
 	list_for_each_entry_safe(chan, _chan, &dw->dma.channels,
 			vc.chan.device_node) {
 		list_del(&chan->vc.chan.device_node);

drivers/dma/dw-axi-dmac/dw-axi-dmac.h

@@ -37,6 +37,7 @@ struct axi_dma_chan {
 	struct axi_dma_chip		*chip;
 	void __iomem			*chan_regs;
 	u8				id;
+	u8				hw_handshake_num;
 	atomic_t			descs_allocated;
 
 	struct dma_pool			*desc_pool;