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path: root/drivers/acpi/pptt.c
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Diffstat (limited to 'drivers/acpi/pptt.c')
-rw-r--r--drivers/acpi/pptt.c61
1 files changed, 55 insertions, 6 deletions
diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c
index b72e6afaa8fb..1e7ac0bd0d3a 100644
--- a/drivers/acpi/pptt.c
+++ b/drivers/acpi/pptt.c
@@ -432,17 +432,40 @@ static void cache_setup_acpi_cpu(struct acpi_table_header *table,
}
}
+static bool flag_identical(struct acpi_table_header *table_hdr,
+ struct acpi_pptt_processor *cpu)
+{
+ struct acpi_pptt_processor *next;
+
+ /* heterogeneous machines must use PPTT revision > 1 */
+ if (table_hdr->revision < 2)
+ return false;
+
+ /* Locate the last node in the tree with IDENTICAL set */
+ if (cpu->flags & ACPI_PPTT_ACPI_IDENTICAL) {
+ next = fetch_pptt_node(table_hdr, cpu->parent);
+ if (!(next && next->flags & ACPI_PPTT_ACPI_IDENTICAL))
+ return true;
+ }
+
+ return false;
+}
+
/* Passing level values greater than this will result in search termination */
#define PPTT_ABORT_PACKAGE 0xFF
-static struct acpi_pptt_processor *acpi_find_processor_package_id(struct acpi_table_header *table_hdr,
- struct acpi_pptt_processor *cpu,
- int level, int flag)
+static struct acpi_pptt_processor *acpi_find_processor_tag(struct acpi_table_header *table_hdr,
+ struct acpi_pptt_processor *cpu,
+ int level, int flag)
{
struct acpi_pptt_processor *prev_node;
while (cpu && level) {
- if (cpu->flags & flag)
+ /* special case the identical flag to find last identical */
+ if (flag == ACPI_PPTT_ACPI_IDENTICAL) {
+ if (flag_identical(table_hdr, cpu))
+ break;
+ } else if (cpu->flags & flag)
break;
pr_debug("level %d\n", level);
prev_node = fetch_pptt_node(table_hdr, cpu->parent);
@@ -480,8 +503,8 @@ static int topology_get_acpi_cpu_tag(struct acpi_table_header *table,
cpu_node = acpi_find_processor_node(table, acpi_cpu_id);
if (cpu_node) {
- cpu_node = acpi_find_processor_package_id(table, cpu_node,
- level, flag);
+ cpu_node = acpi_find_processor_tag(table, cpu_node,
+ level, flag);
/*
* As per specification if the processor structure represents
* an actual processor, then ACPI processor ID must be valid.
@@ -660,3 +683,29 @@ 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() - Get a core architecture tag
+ * @cpu: Kernel logical CPU number
+ *
+ * Determine a unique heterogeneous tag for the given CPU. CPUs with the same
+ * implementation should have matching tags.
+ *
+ * The returned tag 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.
+ *
+ * Due to limitations in the PPTT data structure, there may be rare situations
+ * where two cores in a heterogeneous machine may be identical, but won't have
+ * the same tag.
+ *
+ * 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);
+}