ARM: kernel: provide cluster to logical cpu mask mapping API

Some device drivers like PMU require to retrieve the logical cpu mask
that corresponds to a given cluster id. This patch provides a hook in
the topology code that, given an existing cluster id as input,
initializes the corresponding cpumask passed as a pointer, reusing all
existing topology information required by sched domains in the kernel.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

diff --git a/arch/arm/include/asm/topology.h b/arch/arm/include/asm/topology.h
index 58b8b84adcd2cf5f295e6869b68350f9dcadc798..611edefaeaf195a8de5fa74d283d0f45f254bef2 100644 (file)
--- a/arch/arm/include/asm/topology.h
+++ b/arch/arm/include/asm/topology.h
@@ -26,11 +26,14 @@ extern struct cputopo_arm cpu_topology[NR_CPUS];
 void init_cpu_topology(void);
 void store_cpu_topology(unsigned int cpuid);
 const struct cpumask *cpu_coregroup_mask(int cpu);
+int cluster_to_logical_mask(unsigned int socket_id, cpumask_t *cluster_mask);
 
 #else
 
 static inline void init_cpu_topology(void) { }
 static inline void store_cpu_topology(unsigned int cpuid) { }
+static inline int cluster_to_logical_mask(unsigned int socket_id,
+       cpumask_t *cluster_mask) { return -EINVAL; }
 
 #endif
 

diff --git a/arch/arm/kernel/topology.c b/arch/arm/kernel/topology.c
index c5a59546a256c9b3720022265eb08fcde0dc4f68..e9ac11c85922efc6e7b52bcc22ca2ae9515e6e09 100644 (file)
--- a/arch/arm/kernel/topology.c
+++ b/arch/arm/kernel/topology.c
@@ -289,6 +289,33 @@ void store_cpu_topology(unsigned int cpuid)
                cpu_topology[cpuid].socket_id, mpidr);
 }
 
+/*
+ * cluster_to_logical_mask - return cpu logical mask of CPUs in a cluster
+ * @socket_id:         cluster HW identifier
+ * @cluster_mask:      the cpumask location to be initialized, modified by the
+ *                     function only if return value == 0
+ *
+ * Return:
+ *
+ * 0 on success
+ * -EINVAL if cluster_mask is NULL or there is no record matching socket_id
+ */
+int cluster_to_logical_mask(unsigned int socket_id, cpumask_t *cluster_mask)
+{
+       int cpu;
+
+       if (!cluster_mask)
+               return -EINVAL;
+
+       for_each_online_cpu(cpu)
+               if (socket_id == topology_physical_package_id(cpu)) {
+                       cpumask_copy(cluster_mask, topology_core_cpumask(cpu));
+                       return 0;
+               }
+
+       return -EINVAL;
+}
+
 /*
  * init_cpu_topology is called at boot when only one cpu is running
  * which prevent simultaneous write access to cpu_topology array