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, 22 insertions, 0 deletions

diff --git a/include/linux/of.h b/include/linux/of.h
index ce9f6a2b3532..cf79be1441d2 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -50,6 +50,7 @@ struct device_node {
         const char *type;
         phandle phandle;
         const char *full_name;
+        struct fwnode_handle fwnode;
 
         struct  property *properties;
         struct  property *deadprops;    /* removed properties */
@@ -80,6 +81,7 @@ extern struct kobj_type of_node_ktype;
 static inline void of_node_init(struct device_node *node)
 {
         kobject_init(&node->kobj, &of_node_ktype);
+        node->fwnode.type = FWNODE_OF;
 }
 
 /* true when node is initialized */
@@ -115,6 +117,16 @@ extern struct device_node *of_aliases;
 extern struct device_node *of_stdout;
 extern raw_spinlock_t devtree_lock;
 
+static inline bool is_of_node(struct fwnode_handle *fwnode)
+{
+        return fwnode && fwnode->type == FWNODE_OF;
+}
+
+static inline struct device_node *of_node(struct fwnode_handle *fwnode)
+{
+        return fwnode ? container_of(fwnode, struct device_node, fwnode) : NULL;
+}
+
 static inline bool of_have_populated_dt(void)
 {
         return of_allnodes != NULL;
@@ -360,6 +372,16 @@ bool of_console_check(struct device_node *dn, char *name, int index);
 
 #else /* CONFIG_OF */
 
+static inline bool is_of_node(struct fwnode_handle *fwnode)
+{
+        return false;
+}
+
+static inline struct device_node *of_node(struct fwnode_handle *fwnode)
+{
+        return NULL;
+}
+
 static inline const char* of_node_full_name(const struct device_node *np)
 {
         return "<no-node>";