[PATCH] ppc64: New Open Firmware device tree API, from Nathan Lynch

From: Anton Blanchard <anton@samba.org>

This is an adaptation of the new Open Firmware device tree traversal API from
ppc32, originally written by Benjamin Herrenschmidt.  This patch is against
2.6.0-test3, but should apply ok to the latest 2.5 ameslab tree.

These functions are meant to be SMP-safe alternatives to the current set of
query/traversal routines (find_devices, find_type_devices, et al).

arch/ppc64/kernel/prom.c

@@ -2000,6 +2000,185 @@ find_path_device(const char *path)
 	return NULL;
 }
 
+/*******
+ *
+ * New implementation of the OF "find" APIs, return a refcounted
+ * object, call of_node_put() when done. Currently, still lacks
+ * locking as old implementation, this is being done for ppc64.
+ *
+ * Note that property management will need some locking as well,
+ * this isn't dealt with yet.
+ *
+ *******/
+
+/**
+ *	of_find_node_by_name - Find a node by its "name" property
+ *	@from:	The node to start searching from or NULL, the node
+ *		you pass will not be searched, only the next one
+ *		will; typically, you pass what the previous call
+ *		returned. of_node_put() will be called on it
+ *	@name:	The name string to match against
+ *
+ *	Returns a node pointer with refcount incremented, use
+ *	of_node_put() on it when done.
+ */
+struct device_node *of_find_node_by_name(struct device_node *from,
+	const char *name)
+{
+	struct device_node *np = from ? from->allnext : allnodes;
+
+	for (; np != 0; np = np->allnext)
+		if (np->name != 0 && strcasecmp(np->name, name) == 0)
+			break;
+	if (from)
+		of_node_put(from);
+	return of_node_get(np);
+}
+
+/**
+ *	of_find_node_by_type - Find a node by its "device_type" property
+ *	@from:	The node to start searching from or NULL, the node
+ *		you pass will not be searched, only the next one
+ *		will; typically, you pass what the previous call
+ *		returned. of_node_put() will be called on it
+ *	@name:	The type string to match against
+ *
+ *	Returns a node pointer with refcount incremented, use
+ *	of_node_put() on it when done.
+ */
+struct device_node *of_find_node_by_type(struct device_node *from,
+	const char *type)
+{
+	struct device_node *np = from ? from->allnext : allnodes;
+
+	for (; np != 0; np = np->allnext)
+		if (np->type != 0 && strcasecmp(np->type, type) == 0)
+			break;
+	if (from)
+		of_node_put(from);
+	return of_node_get(np);
+}
+
+/**
+ *	of_find_compatible_node - Find a node based on type and one of the
+ *                                tokens in its "compatible" property
+ *	@from:		The node to start searching from or NULL, the node
+ *			you pass will not be searched, only the next one
+ *			will; typically, you pass what the previous call
+ *			returned. of_node_put() will be called on it
+ *	@type:		The type string to match "device_type" or NULL to ignore
+ *	@compatible:	The string to match to one of the tokens in the device
+ *			"compatible" list.
+ *
+ *	Returns a node pointer with refcount incremented, use
+ *	of_node_put() on it when done.
+ */
+struct device_node *of_find_compatible_node(struct device_node *from,
+	const char *type, const char *compatible)
+{
+	struct device_node *np = from ? from->allnext : allnodes;
+
+	for (; np != 0; np = np->allnext) {
+		if (type != NULL
+		    && !(np->type != 0 && strcasecmp(np->type, type) == 0))
+			continue;
+		if (device_is_compatible(np, compatible))
+			break;
+	}
+	if (from)
+		of_node_put(from);
+	return of_node_get(np);
+}
+
+/**
+ *	of_find_node_by_path - Find a node matching a full OF path
+ *	@path:	The full path to match
+ *
+ *	Returns a node pointer with refcount incremented, use
+ *	of_node_put() on it when done.
+ */
+struct device_node *of_find_node_by_path(const char *path)
+{
+	struct device_node *np = allnodes;
+
+	for (; np != 0; np = np->allnext)
+		if (np->full_name != 0 && strcasecmp(np->full_name, path) == 0)
+			break;
+	return of_node_get(np);
+}
+
+/**
+ *	of_find_all_nodes - Get next node in global list
+ *	@prev:	Previous node or NULL to start iteration
+ *		of_node_put() will be called on it
+ *
+ *	Returns a node pointer with refcount incremented, use
+ *	of_node_put() on it when done.
+ */
+struct device_node *of_find_all_nodes(struct device_node *prev)
+{
+	struct device_node *np = prev ? prev->allnext : allnodes;
+
+	if (prev)
+		of_node_put(prev);
+	return of_node_get(np);
+}
+
+/**
+ *	of_get_parent - Get a node's parent if any
+ *	@node:	Node to get parent
+ *
+ *	Returns a node pointer with refcount incremented, use
+ *	of_node_put() on it when done.
+ */
+struct device_node *of_get_parent(const struct device_node *node)
+{
+	return node ? of_node_get(node->parent) : NULL;
+}
+
+/**
+ *	of_get_next_child - Iterate a node childs
+ *	@node:	parent node
+ *	@prev:	previous child of the parent node, or NULL to get first
+ *
+ *	Returns a node pointer with refcount incremented, use
+ *	of_node_put() on it when done.
+ */
+struct device_node *of_get_next_child(const struct device_node *node,
+	struct device_node *prev)
+{
+	struct device_node *next = prev ? prev->sibling : node->child;
+
+	for (; next != 0; next = next->sibling)
+		if (of_node_get(next))
+			break;
+	if (prev)
+		of_node_put(prev);
+	return next;
+}
+
+/**
+ *	of_node_get - Increment refcount of a node
+ *	@node:	Node to inc refcount, NULL is supported to
+ *		simplify writing of callers
+ *
+ *	Returns the node itself or NULL if gone.
+ */
+struct device_node *of_node_get(struct device_node *node)
+{
+	return node;
+}
+
+/**
+ *	of_node_put - Decrement refcount of a node
+ *	@node:	Node to dec refcount, NULL is supported to
+ *		simplify writing of callers
+ *
+ */
+void of_node_put(struct device_node *node)
+{
+}
+
 /*
  * Find the device_node with a given phandle.
  */

include/asm-ppc64/prom.h

@@ -172,19 +172,36 @@ extern struct prom_t prom;
 
 extern int boot_cpuid;
 
-/* Prototypes */
-extern void abort(void);
-extern unsigned long prom_init(unsigned long, unsigned long, unsigned long,
-    unsigned long, unsigned long);
-extern void prom_print(const char *msg);
-extern void relocate_nodes(void);
-extern void finish_device_tree(void);
+/* OBSOLETE: Old stlye node lookup */
 extern struct device_node *find_devices(const char *name);
 extern struct device_node *find_type_devices(const char *type);
 extern struct device_node *find_path_device(const char *path);
 extern struct device_node *find_compatible_devices(const char *type,
 						   const char *compat);
 extern struct device_node *find_all_nodes(void);
+
+/* New style node lookup */
+extern struct device_node *of_find_node_by_name(struct device_node *from,
+	const char *name);
+extern struct device_node *of_find_node_by_type(struct device_node *from,
+	const char *type);
+extern struct device_node *of_find_compatible_node(struct device_node *from,
+	const char *type, const char *compat);
+extern struct device_node *of_find_node_by_path(const char *path);
+extern struct device_node *of_find_all_nodes(struct device_node *prev);
+extern struct device_node *of_get_parent(const struct device_node *node);
+extern struct device_node *of_get_next_child(const struct device_node *node,
+					     struct device_node *prev);
+extern struct device_node *of_node_get(struct device_node *node);
+extern void of_node_put(struct device_node *node);
+
+/* Other Prototypes */
+extern void abort(void);
+extern unsigned long prom_init(unsigned long, unsigned long, unsigned long,
+	unsigned long, unsigned long);
+extern void prom_print(const char *msg);
+extern void relocate_nodes(void);
+extern void finish_device_tree(void);
 extern int device_is_compatible(struct device_node *device, const char *);
 extern int machine_is_compatible(const char *compat);
 extern unsigned char *get_property(struct device_node *node, const char *name,