[PATCH v4 4/5] dmaengine: arm-dma350: Support integration clocks and resets

[Jelly Jia <Jelly.Jia@cixtech.com>]

DMA-350 integrations may gate the controller with a clock or hold it in
reset. Enable an optional clock and deassert an optional reset before
accessing the controller registers.

Use the deasserted reset helper rather than requesting a reset pulse.
This also supports reset controllers that only implement assert and
deassert operations.

Both resources remain optional, so existing integrations without them
are unchanged.

Signed-off-by: Jelly Jia <Jelly.Jia@cixtech.com>
---
 drivers/dma/arm-dma350.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/dma/arm-dma350.c b/drivers/dma/arm-dma350.c
index f62ff6a9f490..9cb5b2f03113 100644
--- a/drivers/dma/arm-dma350.c
+++ b/drivers/dma/arm-dma350.c
@@ -4,6 +4,7 @@
 
 #include <linux/bitfield.h>
 #include <linux/bitops.h>
+#include <linux/clk.h>
 #include <linux/dmaengine.h>
 #include <linux/dma-mapping.h>
 #include <linux/dmapool.h>
@@ -14,6 +15,7 @@
 #include <linux/module.h>
 #include <linux/overflow.h>
 #include <linux/platform_device.h>
+#include <linux/reset.h>
 #include <linux/scatterlist.h>
 #include <linux/slab.h>
 
@@ -1199,12 +1201,24 @@ static void d350_free_chan_resources(struct dma_chan *chan)
 static int d350_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
+	struct reset_control *reset;
+	struct clk *clk;
 	struct d350 *dmac;
 	void __iomem *base;
 	u32 reg;
 	int ret, nchan, dw, aw, r, p;
 	bool coherent, memset;
 
+	clk = devm_clk_get_optional_enabled(dev, NULL);
+	if (IS_ERR(clk))
+		return dev_err_probe(dev, PTR_ERR(clk),
+				     "failed to enable clock\n");
+
+	reset = devm_reset_control_get_optional_exclusive_deasserted(dev, NULL);
+	if (IS_ERR(reset))
+		return dev_err_probe(dev, PTR_ERR(reset),
+				     "failed to deassert reset\n");
+
 	base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(base))
 		return PTR_ERR(base);
-- 
2.54.0