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Subject[PATCH 1/8] of: base: add of_parse_phandle_with_optional_args()
Date
Add a new variant of the of_parse_phandle_with_args() which treats the
cells name as optional. If it's missing, it is assumed that the phandle
has no arguments.

Up until now, a nvmem node didn't have any arguments, so all the device
trees haven't any '#*-cells' property. But there is a need for an
additional argument for the phandle, for which we need a '#*-cells'
property. Therefore, we need to support nvmem nodes with and without
this property.

Signed-off-by: Michael Walle <michael@walle.cc>
---
drivers/of/base.c | 23 +++++++++++++++++++++++
include/linux/of.h | 12 ++++++++++++
2 files changed, 35 insertions(+)

diff --git a/drivers/of/base.c b/drivers/of/base.c
index 5b907600f5b0..fb28bb26276e 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -1543,6 +1543,29 @@ int of_parse_phandle_with_args(const struct device_node *np, const char *list_na
}
EXPORT_SYMBOL(of_parse_phandle_with_args);

+/**
+ * of_parse_phandle_with_optional_args() - Find a node pointed by phandle in a list
+ *
+ * Same as of_parse_phandle_args() except that if the cells_name property is
+ * not found, cell_count of 0 is assumed.
+ *
+ * This is used to useful, if you have a phandle which didn't have arguments
+ * before and thus doesn't have a '#*-cells' property but is now migrated to
+ * having arguments while retaining backwards compatibility.
+ */
+int of_parse_phandle_with_optional_args(const struct device_node *np,
+ const char *list_name,
+ const char *cells_name, int index,
+ struct of_phandle_args *out_args)
+{
+ if (index < 0)
+ return -EINVAL;
+
+ return __of_parse_phandle_with_args(np, list_name, cells_name,
+ 0, index, out_args);
+}
+EXPORT_SYMBOL(of_parse_phandle_with_optional_args);
+
/**
* of_parse_phandle_with_args_map() - Find a node pointed by phandle in a list and remap it
* @np: pointer to a device tree node containing a list
diff --git a/include/linux/of.h b/include/linux/of.h
index ff143a027abc..ccace453d25f 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -376,6 +376,9 @@ extern int of_parse_phandle_with_args_map(const struct device_node *np,
extern int of_parse_phandle_with_fixed_args(const struct device_node *np,
const char *list_name, int cells_count, int index,
struct of_phandle_args *out_args);
+extern int of_parse_phandle_with_optional_args(const struct device_node *np,
+ const char *list_name, const char *cells_name, int index,
+ struct of_phandle_args *out_args);
extern int of_count_phandle_with_args(const struct device_node *np,
const char *list_name, const char *cells_name);

@@ -897,6 +900,15 @@ static inline int of_parse_phandle_with_fixed_args(const struct device_node *np,
return -ENOSYS;
}

+static inline int of_parse_phandle_with_optional_args(const struct device_node *np,
+ char *list_name,
+ int cells_count,
+ int index,
+ struct of_phandle_args *out_args)
+{
+ return -ENOSYS;
+}
+
static inline int of_count_phandle_with_args(const struct device_node *np,
const char *list_name,
const char *cells_name)
--
2.30.2
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