Commit 5b5d00ab authored by James Morse's avatar James Morse Committed by Zeng Heng
Browse files

ACPI / PPTT: Find PPTT cache level by ID 

maillist inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I8T2RT

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/morse/linux.git/log/?h=mpam/snapshot/v6.7-rc2



---------------------------

The MPAM table identifies caches by id, but the driver also wants to know
the cache level, without having to wait for whichever core has that cache
to come online.

Add a helper that walks every possible cache, until it finds the one
identified by id, then return the level.

Signed-off-by: default avatarJames Morse <james.morse@arm.com>
Signed-off-by: default avatarZeng Heng <zengheng4@huawei.com>
parent 1ab6383e

drivers/acpi/pptt.c

+74 −0
Original line number Diff line number Diff line
@@ -870,3 +870,77 @@ int find_acpi_cpu_topology_hetero_id(unsigned int cpu) 
	return find_acpi_cpu_topology_tag(cpu, PPTT_ABORT_PACKAGE,

					  ACPI_PPTT_ACPI_IDENTICAL);

}





/**

 * find_acpi_cache_level_from_id() - Get the level of the specified cache

 * @cache_id: The id field of the unified cache

 *

 * Determine the level relative to any CPU for the unified cache identified by

 * cache_id. This allows the property to be found even if the CPUs are offline.

 *

 * The returned level can be used to group unified caches that are peers.

 *

 * The PPTT table must be rev 3 or later,

 *

 * If one CPUs L2 is shared with another as L3, this function will return

 * and unpredictable value.

 *

 * Return: -ENOENT if the PPTT doesn't exist, or the cache cannot be found.

 * Otherwise returns a value which represents the level of the specified cache.

 */

int find_acpi_cache_level_from_id(u32 cache_id)

{

	u32 acpi_cpu_id;

	acpi_status status;

	int level, cpu, num_levels;

	struct acpi_pptt_cache *cache;

	struct acpi_table_header *table;

	struct acpi_pptt_cache_v1* cache_v1;

	struct acpi_pptt_processor *cpu_node;



	status = acpi_get_table(ACPI_SIG_PPTT, 0, &table);

	if (ACPI_FAILURE(status)) {

		acpi_pptt_warn_missing();

		return -ENOENT;

	}



	if (table->revision < 3) {

		acpi_put_table(table);

		return -ENOENT;

	}



	/*

	 * If we found the cache first, we'd still need to walk from each CPU

	 * to find the level...

	 */

	for_each_possible_cpu(cpu) {

		acpi_cpu_id = get_acpi_id_for_cpu(cpu);

		cpu_node = acpi_find_processor_node(table, acpi_cpu_id);

		if (!cpu_node)

			break;

		acpi_count_levels(table, cpu_node, &num_levels, NULL);



		/* Start at 1 for L1 */

		for (level = 1; level <= num_levels; level++) {

			cache = acpi_find_cache_node(table, acpi_cpu_id,

						     ACPI_PPTT_CACHE_TYPE_UNIFIED,

						     level, &cpu_node);

			if (!cache)

				continue;



			cache_v1 = ACPI_ADD_PTR(struct acpi_pptt_cache_v1,

						cache,

						sizeof(struct acpi_pptt_cache));



			if (cache->flags & ACPI_PPTT_CACHE_ID_VALID &&

			    cache_v1->cache_id == cache_id) {

				acpi_put_table(table);

				return level;

			}

		}

	}



	acpi_put_table(table);

	return -ENOENT;

}

include/linux/acpi.h

+5 −0
Original line number Diff line number Diff line
@@ -1495,6 +1495,7 @@ int find_acpi_cpu_topology(unsigned int cpu, int level); 
int find_acpi_cpu_topology_cluster(unsigned int cpu);

int find_acpi_cpu_topology_package(unsigned int cpu);

int find_acpi_cpu_topology_hetero_id(unsigned int cpu);

int find_acpi_cache_level_from_id(u32 cache_id);

#else

static inline int acpi_pptt_cpu_is_thread(unsigned int cpu)

{
@@ -1516,6 +1517,10 @@ static inline int find_acpi_cpu_topology_hetero_id(unsigned int cpu) 
{

	return -EINVAL;

}

static inline int find_acpi_cache_level_from_id(u32 cache_id)

{

	return -EINVAL;

}

#endif



#ifdef CONFIG_ARM64