powerpc: Add of_find_next_cache_node()

We have more than one piece of code that looks up cache nodes manually
using the "l2-cache" property.  Add a common helper routine which does
this and handles ePAPR's "next-level-cache" property as well as
powermac.

Signed-off-by: Nathan Lynch <ntl@pobox.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

2 files changed, 34 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/prom.h b/arch/powerpc/include/asm/prom.h
index eb3bd2e1c7f6..6ff04185d2aa 100644
--- a/arch/powerpc/include/asm/prom.h
+++ b/arch/powerpc/include/asm/prom.h
@@ -253,6 +253,9 @@ extern void kdump_move_device_tree(void);
 /* CPU OF node matching */
 struct device_node *of_get_cpu_node(int cpu, unsigned int *thread);
 
+/* cache lookup */
+struct device_node *of_find_next_cache_node(struct device_node *np);
+
 /* Get the MAC address */
 extern const void *of_get_mac_address(struct device_node *np);
 
diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
index 3a2dc7e6586a..d8266dd61dda 100644
--- a/arch/powerpc/kernel/prom.c
+++ b/arch/powerpc/kernel/prom.c
@@ -1271,6 +1271,37 @@ struct device_node *of_find_node_by_phandle(phandle handle)
 EXPORT_SYMBOL(of_find_node_by_phandle);
 
 /**
+ *      of_find_next_cache_node - Find a node's subsidiary cache
+ *      @np:    node of type "cpu" or "cache"
+ *
+ *      Returns a node pointer with refcount incremented, use
+ *      of_node_put() on it when done.  Caller should hold a reference
+ *      to np.
+ */
+struct device_node *of_find_next_cache_node(struct device_node *np)
+{
+        struct device_node *child;
+        const phandle *handle;
+
+        handle = of_get_property(np, "l2-cache", NULL);
+        if (!handle)
+                handle = of_get_property(np, "next-level-cache", NULL);
+
+        if (handle)
+                return of_find_node_by_phandle(*handle);
+
+        /* OF on pmac has nodes instead of properties named "l2-cache"
+         * beneath CPU nodes.
+         */
+        if (!strcmp(np->type, "cpu"))
+                for_each_child_of_node(np, child)
+                        if (!strcmp(child->type, "cache"))
+                                return child;
+
+        return NULL;
+}
+
+/**
  *      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