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ACPI/PPTT: Add function to return ACPI 6.3 Identical tokens

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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.

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Hanjun Guo <hanjun.guo@linaro.org>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Jeremy Linton 2019-06-26 16:37:16 -05:00 committed by Will Deacon
parent ed2b664fcc
commit 56855a99f3
2 changed files with 31 additions and 0 deletions
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26
drivers/acpi/pptt.c
View file

@ -683,3 +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);
}

5
include/linux/acpi.h
View file

@ -1303,6 +1303,7 @@ 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)
@ -1313,6 +1314,10 @@ static inline int find_acpi_cpu_topology_package(unsigned int cpu)
{
return -EINVAL;
}
static inline 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;