[PATCH v3] mfd: syscon: Add arguments support for syscon reference

[Orson Zhai]

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@xxxxxxxxxx>
Tested-by: Baolin Wang <baolin.wang@xxxxxxxxxx>
---
 drivers/mfd/syscon.c       | 29 +++++++++++++++++++++++++++++
 include/linux/mfd/syscon.h | 14 ++++++++++++++
 2 files changed, 43 insertions(+)

diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c
index e22197c..2918b05 100644
--- a/drivers/mfd/syscon.c
+++ b/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;
diff --git a/include/linux/mfd/syscon.h b/include/linux/mfd/syscon.h
index 112dc66..714cab1 100644
--- a/include/linux/mfd/syscon.h
+++ b/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__ */
--
2.7.4

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