Driver core: Unified interface for firmware node properties

Add new generic routines are provided for retrieving properties from
device description objects in the platform firmware in case there are
no struct device objects for them (either those objects have not been
created yet or they do not exist at all).

The following functions are provided:

fwnode_property_present()
fwnode_property_read_u8()
fwnode_property_read_u16()
fwnode_property_read_u32()
fwnode_property_read_u64()
fwnode_property_read_string()
fwnode_property_read_u8_array()
fwnode_property_read_u16_array()
fwnode_property_read_u32_array()
fwnode_property_read_u64_array()
fwnode_property_read_string_array()

in analogy with the corresponding functions for struct device added
previously.  For all of them, the first argument is a pointer to struct
fwnode_handle (new type) that allows a device description object
(depending on what platform firmware interface is in use) to be
obtained.

Add a new macro device_for_each_child_node() for iterating over the
children of the device description object associated with a given
device and a new function device_get_child_node_count() returning the
number of a given device's child nodes.

The interface covers both ACPI and Device Trees.

Suggested-by: Grant Likely <grant.likely@linaro.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Grant Likely <grant.likely@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 70 insertions, 0 deletions

diff --git a/include/linux/property.h b/include/linux/property.h
index 9242fb0221ba..a6a3d98bd7e9 100644
--- a/include/linux/property.h
+++ b/include/linux/property.h
@@ -40,6 +40,46 @@ int device_property_read_string_array(struct device *dev, const char *propname,
 int device_property_read_string(struct device *dev, const char *propname,
 				const char **val);
 
+enum fwnode_type {
+	FWNODE_INVALID = 0,
+	FWNODE_OF,
+	FWNODE_ACPI,
+};
+
+struct fwnode_handle {
+	enum fwnode_type type;
+};
+
+bool fwnode_property_present(struct fwnode_handle *fwnode, const char *propname);
+int fwnode_property_read_u8_array(struct fwnode_handle *fwnode,
+				  const char *propname, u8 *val,
+				  size_t nval);
+int fwnode_property_read_u16_array(struct fwnode_handle *fwnode,
+				   const char *propname, u16 *val,
+				   size_t nval);
+int fwnode_property_read_u32_array(struct fwnode_handle *fwnode,
+				   const char *propname, u32 *val,
+				   size_t nval);
+int fwnode_property_read_u64_array(struct fwnode_handle *fwnode,
+				   const char *propname, u64 *val,
+				   size_t nval);
+int fwnode_property_read_string_array(struct fwnode_handle *fwnode,
+				      const char *propname, const char **val,
+				      size_t nval);
+int fwnode_property_read_string(struct fwnode_handle *fwnode,
+				const char *propname, const char **val);
+
+struct fwnode_handle *device_get_next_child_node(struct device *dev,
+						 struct fwnode_handle *child);
+
+#define device_for_each_child_node(dev, child) \
+	for (child = device_get_next_child_node(dev, NULL); child; \
+	     child = device_get_next_child_node(dev, child))
+
+void fwnode_handle_put(struct fwnode_handle *fwnode);
+
+unsigned int device_get_child_node_count(struct device *dev);
+
 static inline bool device_property_read_bool(struct device *dev,
 					     const char *propname)
 {
@@ -70,4 +110,34 @@ static inline int device_property_read_u64(struct device *dev,
 	return device_property_read_u64_array(dev, propname, val, 1);
 }
 
+static inline bool fwnode_property_read_bool(struct fwnode_handle *fwnode,
+					     const char *propname)
+{
+	return fwnode_property_present(fwnode, propname);
+}
+
+static inline int fwnode_property_read_u8(struct fwnode_handle *fwnode,
+					  const char *propname, u8 *val)
+{
+	return fwnode_property_read_u8_array(fwnode, propname, val, 1);
+}
+
+static inline int fwnode_property_read_u16(struct fwnode_handle *fwnode,
+					   const char *propname, u16 *val)
+{
+	return fwnode_property_read_u16_array(fwnode, propname, val, 1);
+}
+
+static inline int fwnode_property_read_u32(struct fwnode_handle *fwnode,
+					   const char *propname, u32 *val)
+{
+	return fwnode_property_read_u32_array(fwnode, propname, val, 1);
+}
+
+static inline int fwnode_property_read_u64(struct fwnode_handle *fwnode,
+					   const char *propname, u64 *val)
+{
+	return fwnode_property_read_u64_array(fwnode, propname, val, 1);
+}
+
 #endif /* _LINUX_PROPERTY_H_ */