dmagengine: pl330: add code to get reset property

The DMA controller on some SoCs can be held in reset, and thus requires
the reset signal(s) to deasserted. Most SoCs will have just one reset
signal, but there are others, i.e. Arria10/Stratix10 will have an
additional reset signal, referred to as the OCP.

Add code to get the reset property from the device tree for deassert and
assert.
Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>
Signed-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/pl330.c

@@ -29,6 +29,7 @@
 #include <linux/err.h>
 #include <linux/pm_runtime.h>
 #include <linux/bug.h>
+#include <linux/reset.h>
 
 #include "dmaengine.h"
 #define PL330_MAX_CHAN		8
@@ -500,6 +501,9 @@ struct pl330_dmac {
 	unsigned int num_peripherals;
 	struct dma_pl330_chan *peripherals; /* keep at end */
 	int quirks;
+
+	struct reset_control	*rstc;
+	struct reset_control	*rstc_ocp;
 };
 
 static struct pl330_of_quirks {
@@ -3028,6 +3032,32 @@ pl330_probe(struct amba_device *adev, const struct amba_id *id)
 
 	amba_set_drvdata(adev, pl330);
 
+	pl330->rstc = devm_reset_control_get_optional(&adev->dev, "dma");
+	if (IS_ERR(pl330->rstc)) {
+		if (PTR_ERR(pl330->rstc) != -EPROBE_DEFER)
+			dev_err(&adev->dev, "Failed to get reset!\n");
+		return PTR_ERR(pl330->rstc);
+	} else {
+		ret = reset_control_deassert(pl330->rstc);
+		if (ret) {
+			dev_err(&adev->dev, "Couldn't deassert the device from reset!\n");
+			return ret;
+		}
+	}
+
+	pl330->rstc_ocp = devm_reset_control_get_optional(&adev->dev, "dma-ocp");
+	if (IS_ERR(pl330->rstc_ocp)) {
+		if (PTR_ERR(pl330->rstc_ocp) != -EPROBE_DEFER)
+			dev_err(&adev->dev, "Failed to get OCP reset!\n");
+		return PTR_ERR(pl330->rstc_ocp);
+	} else {
+		ret = reset_control_deassert(pl330->rstc_ocp);
+		if (ret) {
+			dev_err(&adev->dev, "Couldn't deassert the device from OCP reset!\n");
+			return ret;
+		}
+	}
+
 	for (i = 0; i < AMBA_NR_IRQS; i++) {
 		irq = adev->irq[i];
 		if (irq) {
@@ -3168,6 +3198,11 @@ pl330_probe(struct amba_device *adev, const struct amba_id *id)
 probe_err2:
 	pl330_del(pl330);
 
+	if (pl330->rstc_ocp)
+		reset_control_assert(pl330->rstc_ocp);
+
+	if (pl330->rstc)
+		reset_control_assert(pl330->rstc);
 	return ret;
 }
 
@@ -3206,6 +3241,11 @@ static int pl330_remove(struct amba_device *adev)
 
 	pl330_del(pl330);
 
+	if (pl330->rstc_ocp)
+		reset_control_assert(pl330->rstc_ocp);
+
+	if (pl330->rstc)
+		reset_control_assert(pl330->rstc);
 	return 0;
 }