[PATCH v3 2/6] of: Add helper for mapping device node to logical CPU number

[Suzuki K Poulose]

Add a helper to map a device node to a logical CPU number to avoid
duplication. Currently this is open coded in different places (e.g
gic-v3, coresight). The helper tries to map device node to a "possible"
logical CPU id, which may not be online yet. It is the responsibility
of the user to make sure that the CPU is online. The helper uses
of_get_cpu_node() which uses arch specific backends to match the phyiscal
ids.

Cc: Rob Herring <robh+dt@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Sudeep Holla <sudeep.holla@xxxxxxx>
Reviewed-by: Marc Zyngier <marc.zyngier@xxxxxxx>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
---
 drivers/of/base.c         | 26 ++++++++++++++++++++++++++
 include/linux/of_device.h |  7 +++++++
 2 files changed, 33 insertions(+)

diff --git a/drivers/of/base.c b/drivers/of/base.c
index 686628d..0b01515 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -420,6 +420,32 @@ struct device_node *of_get_cpu_node(int cpu, unsigned int *thread)
 EXPORT_SYMBOL(of_get_cpu_node);
 
 /**
+ * of_device_node_get_cpu: Get the logical CPU number for a given device_node
+ *
+ * @cpu_node: Pointer to the device_node for CPU.
+ *
+ * Returns the logical CPU number of the given CPU device_node.
+ * Returns >= nr_cpu_ids if CPU is not found.
+ */
+int of_device_node_get_cpu(struct device_node *cpu_node)
+{
+	int cpu;
+	bool found = false;
+	struct device_node *np;
+
+	for_each_possible_cpu(cpu) {
+		np = of_get_cpu_node(cpu, NULL);
+		found = (cpu_node == np);
+		of_node_put(np);
+		if (found)
+			break;
+	}
+
+	return cpu;
+}
+EXPORT_SYMBOL(of_device_node_get_cpu);
+
+/**
  * __of_device_is_compatible() - Check if the node matches given constraints
  * @device: pointer to node
  * @compat: required compatible string, NULL or "" for any match
diff --git a/include/linux/of_device.h b/include/linux/of_device.h
index b4ad8b4..00a4ba9 100644
--- a/include/linux/of_device.h
+++ b/include/linux/of_device.h
@@ -40,6 +40,8 @@ extern int of_device_request_module(struct device *dev);
 extern void of_device_uevent(struct device *dev, struct kobj_uevent_env *env);
 extern int of_device_uevent_modalias(struct device *dev, struct kobj_uevent_env *env);
 
+extern int of_device_node_get_cpu(struct device_node *np);
+
 static inline void of_device_node_put(struct device *dev)
 {
 	of_node_put(dev->of_node);
@@ -110,6 +112,11 @@ static inline int of_dma_configure(struct device *dev, struct device_node *np)
 }
 static inline void of_dma_deconfigure(struct device *dev)
 {}
+
+static inline int of_device_node_get_cpu(struct device_node *np)
+{
+	return nr_cpu_ids;
+}
 #endif /* CONFIG_OF */
 
 #endif /* _LINUX_OF_DEVICE_H */
-- 
2.7.5