@@ -660,3 +660,29 @@ int find_acpi_cpu_topology_package(unsigned int cpu)
return find_acpi_cpu_topology_tag(cpu, PPTT_ABORT_PACKAGE,
ACPI_PPTT_PHYSICAL_PACKAGE);
}
+
+/**
+ * find_acpi_cpu_topology_hetero_id() - Determine a unique implementation
+ * @cpu: Kernel logical cpu number
+ *
+ * Determine a unique heterogeneous ID for the given CPU. CPUs with the same
+ * implementation should have matching IDs. Since this is a tree we can only
+ * detect implementations where the heterogeneous flag is the parent to all
+ * matching cores. AKA if a two socket machine has two different core types
+ * in each socket this will end up being represented as four unique core types
+ * rather than two.
+ *
+ * The returned ID can be used to group peers with identical implementation.
+ *
+ * The search terminates when a level is found with the identical implementation
+ * flag set or we reach a root node.
+ *
+ * Return: -ENOENT if the PPTT doesn't exist, or the cpu cannot be found.
+ * Otherwise returns a value which represents a group of identical cores
+ * similar to this cpu.
+ */
+int find_acpi_cpu_topology_hetero_id(unsigned int cpu)
+{
+ return find_acpi_cpu_topology_tag(cpu, PPTT_ABORT_PACKAGE,
+ ACPI_PPTT_ACPI_IDENTICAL);
+}
@@ -1309,6 +1309,7 @@ static inline int lpit_read_residency_count_address(u64 *address)
#ifdef CONFIG_ACPI_PPTT
int find_acpi_cpu_topology(unsigned int cpu, int level);
int find_acpi_cpu_topology_package(unsigned int cpu);
+int find_acpi_cpu_topology_hetero_id(unsigned int cpu);
int find_acpi_cpu_cache_topology(unsigned int cpu, int level);
#else
static inline int find_acpi_cpu_topology(unsigned int cpu, int level)
@@ -1319,6 +1320,10 @@ static inline int find_acpi_cpu_topology_package(unsigned int cpu)
{
return -EINVAL;
}
+static int find_acpi_cpu_topology_hetero_id(unsigned int cpu)
+{
+ return -EINVAL;
+}
static inline int find_acpi_cpu_cache_topology(unsigned int cpu, int level)
{
return -EINVAL;
ACPI 6.3 adds a flag to indicate that child nodes are all identical cores. This is useful to authoritatively determine if a set of (possibly offline) cores are identical or not. Since the flag doesn't give us a unique id we can generate one and use it to create bitmaps of sibling nodes, or simply in a loop to determine if a subset of cores are identical. Signed-off-by: Jeremy Linton <jeremy.linton@arm.com> --- drivers/acpi/pptt.c | 26 ++++++++++++++++++++++++++ include/linux/acpi.h | 5 +++++ 2 files changed, 31 insertions(+) -- 2.20.1