[PATCH v4 1/2] drivers: base: cacheinfo: Add variable to record max cache line size

[Shaokun Zhang]

Add coherency_max_size variable to record the maximum cache line size
for different cache levels. If it is available, we will synchronize
it as cache line size, otherwise we will use CTR_EL0.CWG reporting
in cache_line_size() for arm64.

Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
Cc: Sudeep Holla <sudeep.holla@xxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Jeremy Linton <jeremy.linton@xxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Shaokun Zhang <zhangshaokun@xxxxxxxxxxxxx>
---
ChangeLog since v3:
  -- Address Greg's comments
  -- Fix some commit information

ChangeLog since v2:
  -- Rebase to 5.2-rc2
  -- Export cache_line_size for I/O driver

ChangeLog since v1:
  -- Move coherency_max_size to drivers/base/cacheinfo.c
  -- Address Catalin's comments
  Link: https://www.spinics.net/lists/arm-kernel/msg723615.html

 drivers/base/cacheinfo.c  | 5 +++++
 include/linux/cacheinfo.h | 2 ++
 2 files changed, 7 insertions(+)

diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c
index a7359535caf5..8827c60f51e2 100644
--- a/drivers/base/cacheinfo.c
+++ b/drivers/base/cacheinfo.c
@@ -213,6 +213,8 @@ int __weak cache_setup_acpi(unsigned int cpu)
 	return -ENOTSUPP;
 }
 
+unsigned int coherency_max_size;
+
 static int cache_shared_cpu_map_setup(unsigned int cpu)
 {
 	struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
@@ -251,6 +253,9 @@ static int cache_shared_cpu_map_setup(unsigned int cpu)
 				cpumask_set_cpu(i, &this_leaf->shared_cpu_map);
 			}
 		}
+		/* record the maximum cache line size */
+		if (this_leaf->coherency_line_size > coherency_max_size)
+			coherency_max_size = this_leaf->coherency_line_size;
 	}
 
 	return 0;
diff --git a/include/linux/cacheinfo.h b/include/linux/cacheinfo.h
index 70e19bc6cc9f..46b92cd61d0c 100644
--- a/include/linux/cacheinfo.h
+++ b/include/linux/cacheinfo.h
@@ -17,6 +17,8 @@ enum cache_type {
 	CACHE_TYPE_UNIFIED = BIT(2),
 };
 
+extern unsigned int coherency_max_size;
+
 /**
  * struct cacheinfo - represent a cache leaf node
  * @id: This cache's id. It is unique among caches with the same (type, level).
-- 
2.7.4