power: reset: at91: add sama5d3 reset function

This patch introduces a new compatible string: "atmel,sama5d3-rstc" and
new reset function for sama5d3 and later chips.

As in sama5d3 or later chips, we don't have to shutdown the DDR
controller before reset. Shutdown the DDR controller before reset is a
workaround to avoid DDR signal driving the bus, but since sama5d3 and
later chips there is no such a conflict.

So in this patch:
   1. the sama5d3 reset function only need to write the rstc register
and return.
   2. we can remove the code related with sama5d3 DDR controller as
we don't use it at all.

Signed-off-by: Josh Wu <josh.wu@atmel.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sebastian Reichel <sre@kernel.org>

Documentation/devicetree/bindings/arm/atmel-at91.txt

@@ -87,7 +87,7 @@ One interrupt per TC channel in a TC block:
 
 RSTC Reset Controller required properties:
 - compatible: Should be "atmel,<chip>-rstc".
-  <chip> can be "at91sam9260" or "at91sam9g45"
+  <chip> can be "at91sam9260" or "at91sam9g45" or "sama5d3"
 - reg: Should contain registers location and length
 
 Example:

drivers/power/reset/at91-reset.c

@@ -123,6 +123,15 @@ static int at91sam9g45_restart(struct notifier_block *this, unsigned long mode,
 	return NOTIFY_DONE;
 }
 
+static int sama5d3_restart(struct notifier_block *this, unsigned long mode,
+			   void *cmd)
+{
+	writel(cpu_to_le32(AT91_RSTC_KEY | AT91_RSTC_PERRST | AT91_RSTC_PROCRST),
+	       at91_rstc_base);
+
+	return NOTIFY_DONE;
+}
+
 static void __init at91_reset_status(struct platform_device *pdev)
 {
 	u32 reg = readl(at91_rstc_base + AT91_RSTC_SR);
@@ -155,13 +164,13 @@ static void __init at91_reset_status(struct platform_device *pdev)
 static const struct of_device_id at91_ramc_of_match[] = {
 	{ .compatible = "atmel,at91sam9260-sdramc", },
 	{ .compatible = "atmel,at91sam9g45-ddramc", },
-	{ .compatible = "atmel,sama5d3-ddramc", },
 	{ /* sentinel */ }
 };
 
 static const struct of_device_id at91_reset_of_match[] = {
 	{ .compatible = "atmel,at91sam9260-rstc", .data = at91sam9260_restart },
 	{ .compatible = "atmel,at91sam9g45-rstc", .data = at91sam9g45_restart },
+	{ .compatible = "atmel,sama5d3-rstc", .data = sama5d3_restart },
 	{ /* sentinel */ }
 };
 
@@ -181,13 +190,16 @@ static int at91_reset_of_probe(struct platform_device *pdev)
 		return -ENODEV;
 	}
 
-	for_each_matching_node(np, at91_ramc_of_match) {
-		at91_ramc_base[idx] = of_iomap(np, 0);
-		if (!at91_ramc_base[idx]) {
-			dev_err(&pdev->dev, "Could not map ram controller address\n");
-			return -ENODEV;
+	if (!of_device_is_compatible(pdev->dev.of_node, "atmel,sama5d3-rstc")) {
+		/* we need to shutdown the ddr controller, so get ramc base */
+		for_each_matching_node(np, at91_ramc_of_match) {
+			at91_ramc_base[idx] = of_iomap(np, 0);
+			if (!at91_ramc_base[idx]) {
+				dev_err(&pdev->dev, "Could not map ram controller address\n");
+				return -ENODEV;
+			}
+			idx++;
 		}
-		idx++;
 	}
 
 	match = of_match_node(at91_reset_of_match, pdev->dev.of_node);