of: Add helper for mapping device node to logical CPU number

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_cpu_device_node_get() to retrieve the device node for a given CPU
(which uses per_cpu data if available else falls back to slower
of_get_cpu_node()).

Cc: devicetree@vger.kernel.org
Cc: Frank Rowand <frowand.list@gmail.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

diff --git a/drivers/of/base.c b/drivers/of/base.c
index 26618ba8f92a55e8d42db822b507bb8e8827e49f..a9d6fe86585bb6f05647839e481df94a8493a1c4 100644 (file)
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -315,6 +315,32 @@ struct device_node *of_get_cpu_node(int cpu, unsigned int *thread)
 }
 EXPORT_SYMBOL(of_get_cpu_node);
 
+/**
+ * of_cpu_node_to_id: 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 -ENODEV if the CPU is not found.
+ */
+int of_cpu_node_to_id(struct device_node *cpu_node)
+{
+       int cpu;
+       bool found = false;
+       struct device_node *np;
+
+       for_each_possible_cpu(cpu) {
+               np = of_cpu_device_node_get(cpu);
+               found = (cpu_node == np);
+               of_node_put(np);
+               if (found)
+                       return cpu;
+       }
+
+       return -ENODEV;
+}
+EXPORT_SYMBOL(of_cpu_node_to_id);
+
 /**
  * __of_device_is_compatible() - Check if the node matches given constraints
  * @device: pointer to node

diff --git a/include/linux/of.h b/include/linux/of.h
index d3dea1d1e3a95ff27dc56c14cc2dcd89565be1a6..173102dafb07131da6fc9b5af19e3c38e0bc1140 100644 (file)
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -544,6 +544,8 @@ const char *of_prop_next_string(struct property *prop, const char *cur);
 
 bool of_console_check(struct device_node *dn, char *name, int index);
 
+extern int of_cpu_node_to_id(struct device_node *np);
+
 #else /* CONFIG_OF */
 
 static inline void of_core_init(void)
@@ -916,6 +918,11 @@ static inline void of_property_clear_flag(struct property *p, unsigned long flag
 {
 }
 
+static inline int of_cpu_node_to_id(struct device_node *np)
+{
+       return -ENODEV;
+}
+
 #define of_match_ptr(_ptr)     NULL
 #define of_match_node(_matches, _node) NULL
 #endif /* CONFIG_OF */