of: move of_get_cpu_node implementation to DT core library

This patch moves the generalized implementation of of_get_cpu_node from
PowerPC to DT core library, thereby adding support for retrieving cpu
node for a given logical cpu index on any architecture.

The CPU subsystem can now use this function to assign of_node in the
cpu device while registering CPUs.

It is recommended to use these helper function only in pre-SMP/early
initialisation stages to retrieve CPU device node pointers in logical
ordering. Once the cpu devices are registered, it can be retrieved easily
from cpu device of_node which avoids unnecessary parsing and matching.

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Grant Likely <grant.likely@linaro.org>
Acked-by: Rob Herring <rob.herring@calxeda.com>
Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/include/linux/of.h b/include/linux/of.h
index 1fd08ca23106..c0bb2f188048 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -266,6 +266,7 @@ extern int of_device_is_available(const struct device_node *device);
 extern const void *of_get_property(const struct device_node *node,
                                 const char *name,
                                 int *lenp);
+extern struct device_node *of_get_cpu_node(int cpu, unsigned int *thread);
 #define for_each_property_of_node(dn, pp) \
         for (pp = dn->properties; pp != NULL; pp = pp->next)
 
@@ -459,6 +460,12 @@ static inline const void *of_get_property(const struct device_node *node,
         return NULL;
 }
 
+static inline struct device_node *of_get_cpu_node(int cpu,
+                                        unsigned int *thread)
+{
+        return NULL;
+}
+
 static inline int of_property_read_u64(const struct device_node *np,
                                        const char *propname, u64 *out_value)
 {