mfd: syscon: Add arguments support for syscon reference

There are a lot of similar global registers being used across multiple SoCs
from Unisoc. But most of these registers are assigned with different offset
for different SoCs. It is hard to handle all of them in an all-in-one
kernel image.

Add a helper function to get regmap with arguments where we could put some
extra information such as the offset value.
Signed-off-by: Orson Zhai <orson.zhai@unisoc.com>
Tested-by: Baolin Wang <baolin.wang@unisoc.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/syscon.c

@@ -224,6 +224,35 @@ struct regmap *syscon_regmap_lookup_by_phandle(struct device_node *np,
 }
 EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_phandle);
 
+struct regmap *syscon_regmap_lookup_by_phandle_args(struct device_node *np,
+					const char *property,
+					int arg_count,
+					unsigned int *out_args)
+{
+	struct device_node *syscon_np;
+	struct of_phandle_args args;
+	struct regmap *regmap;
+	unsigned int index;
+	int rc;
+
+	rc = of_parse_phandle_with_fixed_args(np, property, arg_count,
+			0, &args);
+	if (rc)
+		return ERR_PTR(rc);
+
+	syscon_np = args.np;
+	if (!syscon_np)
+		return ERR_PTR(-ENODEV);
+
+	regmap = syscon_node_to_regmap(syscon_np);
+	for (index = 0; index < arg_count; index++)
+		out_args[index] = args.args[index];
+	of_node_put(syscon_np);
+
+	return regmap;
+}
+EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_phandle_args);
+
 static int syscon_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;

include/linux/mfd/syscon.h

@@ -23,6 +23,11 @@ extern struct regmap *syscon_regmap_lookup_by_compatible(const char *s);
 extern struct regmap *syscon_regmap_lookup_by_phandle(
 					struct device_node *np,
 					const char *property);
+extern struct regmap *syscon_regmap_lookup_by_phandle_args(
+					struct device_node *np,
+					const char *property,
+					int arg_count,
+					unsigned int *out_args);
 #else
 static inline struct regmap *device_node_to_regmap(struct device_node *np)
 {
@@ -45,6 +50,15 @@ static inline struct regmap *syscon_regmap_lookup_by_phandle(
 {
 	return ERR_PTR(-ENOTSUPP);
 }
+
+static struct regmap *syscon_regmap_lookup_by_phandle_args(
+					struct device_node *np,
+					const char *property,
+					int arg_count,
+					unsigned int *out_args)
+{
+	return ERR_PTR(-ENOTSUPP);
+}
 #endif
 
 #endif /* __LINUX_MFD_SYSCON_H__ */