[PATCH v2 1/2] drivers: base: cacheinfo: Add variable to record max cache line size

[PATCH v2 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. We will synchronize it with CTR_EL0.CWG
reporting in cache_line_size() for arm64.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Jeremy Linton <jeremy.linton@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
---
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


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[PATCH v2 2/2] arm64: cacheinfo: Update cache_line_size detected from DT or PPTT

[Shaokun Zhang]

cache_line_size is derived from CTR_EL0.CWG field and is called mostly
for I/O device drivers. For HiSilicon certain plantform, like the
Kunpeng920 server SoC, cache line sizes are different between L1/2
cache and L3 cache while L1 cache line size is 64-byte and L3 is 128-byte,
but CTR_EL0.CWG is misreporting using L1 cache line size.

We shall correct the right value which is important for I/O performance.
Let's update the cache line size if it is detected from DT or PPTT
information.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: Jeremy Linton <jeremy.linton@arm.com>
Reported-by: Zhenfa Qiu <qiuzhenfa@hisilicon.com>
Suggested-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
---
 arch/arm64/include/asm/cache.h |  6 +-----
 arch/arm64/kernel/cacheinfo.c  | 10 ++++++++++
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/include/asm/cache.h b/arch/arm64/include/asm/cache.h
index 926434f413fa..758af6340314 100644
--- a/arch/arm64/include/asm/cache.h
+++ b/arch/arm64/include/asm/cache.h
@@ -91,11 +91,7 @@ static inline u32 cache_type_cwg(void)
 
 #define __read_mostly __attribute__((__section__(".data..read_mostly")))
 
-static inline int cache_line_size(void)
-{
-	u32 cwg = cache_type_cwg();
-	return cwg ? 4 << cwg : ARCH_DMA_MINALIGN;
-}
+int cache_line_size(void);
 
 /*
  * Read the effective value of CTR_EL0.
diff --git a/arch/arm64/kernel/cacheinfo.c b/arch/arm64/kernel/cacheinfo.c
index 0bf0a835122f..6ffe908d476c 100644
--- a/arch/arm64/kernel/cacheinfo.c
+++ b/arch/arm64/kernel/cacheinfo.c
@@ -28,6 +28,16 @@
 #define CLIDR_CTYPE(clidr, level)	\
 	(((clidr) & CLIDR_CTYPE_MASK(level)) >> CLIDR_CTYPE_SHIFT(level))
 
+int cache_line_size(void)
+{
+	u32 cwg = cache_type_cwg();
+
+	if (coherency_max_size != 0)
+		return coherency_max_size;
+
+	return cwg ? 4 << cwg : ARCH_DMA_MINALIGN;
+}
+
 static inline enum cache_type get_cache_type(int level)
 {
 	u64 clidr;
-- 
2.7.4


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