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, 26 insertions, 0 deletions

diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 38296d686c55..5b8802216a93 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -440,6 +440,23 @@ struct platform_device *acpi_create_platform_device(struct acpi_device *);
 #define ACPI_COMPANION_SET(dev, adev)   do { } while (0)
 #define ACPI_HANDLE(dev)                (NULL)
 
+struct fwnode_handle;
+
+static inline bool is_acpi_node(struct fwnode_handle *fwnode)
+{
+        return false;
+}
+
+static inline struct acpi_device *acpi_node(struct fwnode_handle *fwnode)
+{
+        return NULL;
+}
+
+static inline struct fwnode_handle *acpi_fwnode_handle(struct acpi_device *adev)
+{
+        return NULL;
+}
+
 static inline const char *acpi_dev_name(struct acpi_device *adev)
 {
         return NULL;
@@ -681,6 +698,9 @@ int acpi_dev_prop_read_single(struct acpi_device *adev, const char *propname,
                               enum dev_prop_type proptype, void *val);
 int acpi_dev_prop_read(struct acpi_device *adev, const char *propname,
                        enum dev_prop_type proptype, void *val, size_t nval);
+
+struct acpi_device *acpi_get_next_child(struct device *dev,
+                                        struct acpi_device *child);
 #else
 static inline int acpi_dev_get_property(struct acpi_device *adev,
                                         const char *name, acpi_object_type type,
@@ -725,6 +745,12 @@ static inline int acpi_dev_prop_read(struct acpi_device *adev,
         return -ENXIO;
 }
 
+static inline struct acpi_device *acpi_get_next_child(struct device *dev,
+                                                      struct acpi_device *child)
+{
+        return NULL;
+}
+
 #endif
 
 #endif  /*_LINUX_ACPI_H*/