[PATCH V2 2/2] mfd: syscon: Find syscon by names with arguments support

[Orson Zhai <orson.zhai@unisoc.com>]

There are a lot of global registers used across multiple similar SoCs
from Unisoc. It is not easy to manage all of them very well by current
syscon helper functions.

Add helper functions to get regmap and arguments by syscon-names all
together.

This patch does not affect original syscon code and usage. It may help
other SoC vendors if they have the same trouble as well.

Signed-off-by: Orson Zhai <orson.zhai@unisoc.com>
---
 drivers/mfd/syscon.c       | 75 ++++++++++++++++++++++++++++++++++++++
 include/linux/mfd/syscon.h | 26 +++++++++++++
 2 files changed, 101 insertions(+)

diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c
index 660723276481..e818decc7bf2 100644
--- a/drivers/mfd/syscon.c
+++ b/drivers/mfd/syscon.c
@@ -225,6 +225,81 @@ 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_name(struct device_node *np,
+                                       const char *list_name,
+                                       const char *cell_name)
+{
+       struct device_node *syscon_np;
+       struct of_phandle_args args;
+       struct regmap *regmap;
+       unsigned int index = 0, cell_count = 0;
+       int rc;
+
+       if (list_name)
+               index = of_property_match_string(np, "syscon-names", list_name);
+
+       if (index < 0)
+               return ERR_PTR(-EINVAL);
+
+
+       if (cell_name && of_property_read_u32(np, cell_name, &cell_count))
+               return ERR_PTR(-EINVAL);
+
+       rc = of_parse_phandle_with_fixed_args(np, "syscons", cell_count,
+                                                index, &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);
+
+       of_node_put(syscon_np);
+
+       return regmap;
+}
+EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_name);
+
+int syscon_get_args_by_name(struct device_node *np,
+                       const char *list_name,
+                       const char *cell_name,
+                       int arg_count,
+                       unsigned int *out_args)
+{
+       struct of_phandle_args args;
+       unsigned int index = 0, cell_count = 0;
+
+       int rc;
+
+       if (list_name)
+               index = of_property_match_string(np, "syscon-names", list_name);
+
+       if (index < 0)
+               return -EINVAL;
+
+       if (cell_name && of_property_read_u32(np, cell_name, &cell_count))
+               return -EINVAL;
+
+       rc = of_parse_phandle_with_fixed_args(np, "syscons", cell_count,
+                                               index, &args);
+       if (rc)
+               return rc;
+
+       if (arg_count > args.args_count)
+               arg_count = args.args_count;
+
+       for (index = 0; index < arg_count; index++)
+               out_args[index] = args.args[index];
+
+       of_node_put(args.np);
+
+       return arg_count;
+}
+EXPORT_SYMBOL_GPL(syscon_get_args_by_name);
+
 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 112dc66262cc..96bdaf3e63fd 100644
--- a/include/linux/mfd/syscon.h
+++ b/include/linux/mfd/syscon.h
@@ -23,6 +23,15 @@ 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_name(
+                                       struct device_node *np,
+                                       const char *list_name,
+                                       const char *cell_name);
+extern int syscon_get_args_by_name(struct device_node *np,
+                               const char *list_name,
+                               const char *cell_name,
+                               int arg_count,
+                               unsigned int *out_args);
 #else
 static inline struct regmap *device_node_to_regmap(struct device_node *np)
 {
@@ -45,6 +54,23 @@ static inline struct regmap *syscon_regmap_lookup_by_phandle(
 {
        return ERR_PTR(-ENOTSUPP);
 }
+
+static inline struct regmap *syscon_regmap_lookup_by_name(
+                                       struct device_node *np,
+                                       const char *list_name,
+                                       const char *cell_name)
+{
+       return ERR_PTR(-ENOTSUPP);
+}
+
+static int syscon_get_args_by_name(struct device_node *np,
+                               const char *list_name,
+                               const char *cell_name,
+                               int arg_count,
+                               unsigned int *out_args)
+{
+       return -ENOTSUPP;
+}
 #endif

 #endif /* __LINUX_MFD_SYSCON_H__ */
--
2.18.0

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