clk: sprd: support to get regmap from parent node

Some SC9863a clock nodes would be the child of a syscon node, clocks can
use the regmap of syscon device directly for this kind of cases.
Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
Link: https://lkml.kernel.org/r/20200304072730.9193-7-zhang.lyra@gmail.comSigned-off-by: Stephen Boyd <sboyd@kernel.org>

drivers/clk/sprd/common.c

@@ -40,7 +40,8 @@ int sprd_clk_regmap_init(struct platform_device *pdev,
 			 const struct sprd_clk_desc *desc)
 {
 	void __iomem *base;
-	struct device_node *node = pdev->dev.of_node;
+	struct device *dev = &pdev->dev;
+	struct device_node *node = dev->of_node;
 	struct regmap *regmap;
 
 	if (of_find_property(node, "sprd,syscon", NULL)) {
@@ -49,6 +50,13 @@ int sprd_clk_regmap_init(struct platform_device *pdev,
 			pr_err("%s: failed to get syscon regmap\n", __func__);
 			return PTR_ERR(regmap);
 		}
+	} else if (of_device_is_compatible(of_get_parent(dev->of_node),
+			   "syscon")) {
+		regmap = device_node_to_regmap(of_get_parent(dev->of_node));
+		if (IS_ERR(regmap)) {
+			dev_err(dev, "failed to get regmap from its parent.\n");
+			return PTR_ERR(regmap);
+		}
 	} else {
 		base = devm_platform_ioremap_resource(pdev, 0);
 		if (IS_ERR(base))