[RFC PATCH 04/36] cacheinfo: Expose the code to generate a cache-id from a device_node
From: James Morse <james.morse@arm.com>
Date: 2025-07-11 18:37:17
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lkml
Subsystem:
driver core, kobjects, debugfs and sysfs, the rest · Maintainers:
Greg Kroah-Hartman, "Rafael J. Wysocki", Danilo Krummrich, Linus Torvalds
The MPAM driver identifies caches by id for use with resctrl. It needs to know the cache-id when probe-ing, but the value isn't set in cacheinfo until device_initcall(). Expose the code that generates the cache-id. The parts of the MPAM driver that run early can use this to set up the resctrl structures before cacheinfo is ready in device_initcall(). Signed-off-by: James Morse <james.morse@arm.com> --- Changes since v1: * Renamed cache_of_get_id() cache_of_calculate_id(). --- drivers/base/cacheinfo.c | 17 ++++++++++++----- include/linux/cacheinfo.h | 1 + 2 files changed, 13 insertions(+), 5 deletions(-)
diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c
index 613410705a47..0fdd6358ee73 100644
--- a/drivers/base/cacheinfo.c
+++ b/drivers/base/cacheinfo.c@@ -207,8 +207,7 @@ static bool match_cache_node(struct device_node *cpu, #define arch_compact_of_hwid(_x) (_x) #endif -static void cache_of_set_id(struct cacheinfo *this_leaf, - struct device_node *cache_node) +unsigned long cache_of_calculate_id(struct device_node *cache_node) { struct device_node *cpu; u32 min_id = ~0;
@@ -219,15 +218,23 @@ static void cache_of_set_id(struct cacheinfo *this_leaf, id = arch_compact_of_hwid(id); if (FIELD_GET(GENMASK_ULL(63, 32), id)) { of_node_put(cpu); - return; + return ~0UL; } if (match_cache_node(cpu, cache_node)) min_id = min(min_id, id); } - if (min_id != ~0) { - this_leaf->id = min_id; + return min_id; +} + +static void cache_of_set_id(struct cacheinfo *this_leaf, + struct device_node *cache_node) +{ + unsigned long id = cache_of_calculate_id(cache_node); + + if (id != ~0UL) { + this_leaf->id = id; this_leaf->attributes |= CACHE_ID; } }
diff --git a/include/linux/cacheinfo.h b/include/linux/cacheinfo.h
index c8f4f0a0b874..2dcbb69139e9 100644
--- a/include/linux/cacheinfo.h
+++ b/include/linux/cacheinfo.h@@ -112,6 +112,7 @@ int acpi_get_cache_info(unsigned int cpu, #endif const struct attribute_group *cache_get_priv_group(struct cacheinfo *this_leaf); +unsigned long cache_of_calculate_id(struct device_node *np); /* * Get the cacheinfo structure for the cache associated with @cpu at
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2.39.5