[PATCH v2 1/2] of: base: add support to find the level of the last cache

[PATCH v2 1/2] of: base: add support to find the level of the last cache

[Sudeep Holla]

It is useful to have helper function just to get the number of cache
levels for a given logical cpu. We can obtain the same by just checking
the level at which the last cache is present. This patch adds support
to find the level of the last cache for a given cpu.

It will be used on ARM64 platform where the device tree provides the
information for the additional non-architected/transparent/external
last level caches that are not integrated with the processors.

Suggested-by: Rob Herring <robh+dt@kernel.org>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
---
 drivers/of/base.c  | 27 +++++++++++++++++++++++++++
 include/linux/of.h |  1 +
 2 files changed, 28 insertions(+)

v1->v2:
	- Moved to using "cache-level" in the last level cache instead
	  of counting through all the nodes as suggested by Rob

diff --git a/drivers/of/base.c b/drivers/of/base.c
index d4bea3c797d6..c1128a077aea 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -25,6 +25,7 @@
 #include <linux/cpu.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/of_device.h>
 #include <linux/of_graph.h>
 #include <linux/spinlock.h>
 #include <linux/slab.h>
@@ -2268,6 +2269,32 @@ struct device_node *of_find_next_cache_node(const struct device_node *np)
 }

 /**
+ * of_find_last_cache_level - Find the level at which the last cache is
+ * 		present for the given logical cpu
+ *
+ * @cpu: cpu number(logical index) for which the last cache level is needed
+ *
+ * Returns the the level at which the last cache is present. It is exactly
+ * same as  the total number of cache levels for the given logical cpu.
+ */
+int of_find_last_cache_level(unsigned int cpu)
+{
+	int cache_level = 0;
+	struct device_node *prev = NULL, *np = of_cpu_device_node_get(cpu);
+
+	while (np) {
+		prev = np;
+		of_node_put(np);
+		np = of_find_next_cache_node(np);
+	}
+
+	if (prev)
+		of_property_read_u32(prev, "cache-level", &cache_level);
+
+	return cache_level;
+}
+
+/**
  * of_graph_parse_endpoint() - parse common endpoint node properties
  * @node: pointer to endpoint device_node
  * @endpoint: pointer to the OF endpoint data structure
diff --git a/include/linux/of.h b/include/linux/of.h
index d72f01009297..21e6323de0f3 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -280,6 +280,7 @@ extern struct device_node *of_get_child_by_name(const struct device_node *node,

 /* cache lookup */
 extern struct device_node *of_find_next_cache_node(const struct device_node *);
+extern int of_find_last_cache_level(unsigned int cpu);
 extern struct device_node *of_find_node_with_property(
 	struct device_node *from, const char *prop_name);

--
2.7.4

[PATCH v2 2/2] arm64: cacheinfo: add support to override cache levels via device tree

[Sudeep Holla]

The cache hierarchy can be identified through Cache Level ID(CLIDR)
architected system register. However in some cases it will provide
only the number of cache levels that are integrated into the processor
itself. In other words, it can't provide any information about the
caches that are external and/or transparent.

Some platforms require to export the information about all such external
caches to the userspace applications via the sysfs interface.

This patch adds support to override the cache levels using device tree
to take such external non-architected caches into account.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
---
 arch/arm64/kernel/cacheinfo.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/cacheinfo.c b/arch/arm64/kernel/cacheinfo.c
index 9617301f76b5..3f2250fc391b 100644
--- a/arch/arm64/kernel/cacheinfo.c
+++ b/arch/arm64/kernel/cacheinfo.c
@@ -84,7 +84,7 @@ static void ci_leaf_init(struct cacheinfo *this_leaf,

 static int __init_cache_level(unsigned int cpu)
 {
-	unsigned int ctype, level, leaves;
+	unsigned int ctype, level, leaves, of_level;
 	struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);

 	for (level = 1, leaves = 0; level <= MAX_CACHE_LEVEL; level++) {
@@ -97,6 +97,17 @@ static int __init_cache_level(unsigned int cpu)
 		leaves += (ctype == CACHE_TYPE_SEPARATE) ? 2 : 1;
 	}

+	of_level = of_find_last_cache_level(cpu);
+	if (level < of_level) {
+		/*
+		 * some external caches not specified in CLIDR_EL1
+		 * the information may be available in the device tree
+		 * only unified external caches are considered here
+		 */
+		leaves += (of_level - level);
+		level = of_level;
+	}
+
 	this_cpu_ci->num_levels = level;
 	this_cpu_ci->num_leaves = leaves;
 	return 0;
--
2.7.4

Re: [PATCH v2 1/2] of: base: add support to find the level of the last cache

[Tan Xiaojun]

On 2017/1/13 2:29, Sudeep Holla wrote:
> It is useful to have helper function just to get the number of cache
> levels for a given logical cpu. We can obtain the same by just checking
> the level at which the last cache is present. This patch adds support
> to find the level of the last cache for a given cpu.
> 
> It will be used on ARM64 platform where the device tree provides the
> information for the additional non-architected/transparent/external
> last level caches that are not integrated with the processors.
> 
> Suggested-by: Rob Herring <robh+dt@kernel.org>
> Cc: Rob Herring <robh+dt@kernel.org>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

Tested-by: Tan Xiaojun <tanxiaojun@huawei.com>

> ---
>  drivers/of/base.c  | 27 +++++++++++++++++++++++++++
>  include/linux/of.h |  1 +
>  2 files changed, 28 insertions(+)
> 
> v1->v2:
> 	- Moved to using "cache-level" in the last level cache instead
> 	  of counting through all the nodes as suggested by Rob
> 
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index d4bea3c797d6..c1128a077aea 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -25,6 +25,7 @@
>  #include <linux/cpu.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
> +#include <linux/of_device.h>
>  #include <linux/of_graph.h>
>  #include <linux/spinlock.h>
>  #include <linux/slab.h>
> @@ -2268,6 +2269,32 @@ struct device_node *of_find_next_cache_node(const struct device_node *np)
>  }
> 
>  /**
> + * of_find_last_cache_level - Find the level at which the last cache is
> + * 		present for the given logical cpu
> + *
> + * @cpu: cpu number(logical index) for which the last cache level is needed
> + *
> + * Returns the the level at which the last cache is present. It is exactly
> + * same as  the total number of cache levels for the given logical cpu.
> + */
> +int of_find_last_cache_level(unsigned int cpu)
> +{
> +	int cache_level = 0;
> +	struct device_node *prev = NULL, *np = of_cpu_device_node_get(cpu);
> +
> +	while (np) {
> +		prev = np;
> +		of_node_put(np);
> +		np = of_find_next_cache_node(np);
> +	}
> +
> +	if (prev)
> +		of_property_read_u32(prev, "cache-level", &cache_level);
> +
> +	return cache_level;
> +}
> +
> +/**
>   * of_graph_parse_endpoint() - parse common endpoint node properties
>   * @node: pointer to endpoint device_node
>   * @endpoint: pointer to the OF endpoint data structure
> diff --git a/include/linux/of.h b/include/linux/of.h
> index d72f01009297..21e6323de0f3 100644
> --- a/include/linux/of.h
> +++ b/include/linux/of.h
> @@ -280,6 +280,7 @@ extern struct device_node *of_get_child_by_name(const struct device_node *node,
> 
>  /* cache lookup */
>  extern struct device_node *of_find_next_cache_node(const struct device_node *);
> +extern int of_find_last_cache_level(unsigned int cpu);
>  extern struct device_node *of_find_node_with_property(
>  	struct device_node *from, const char *prop_name);
> 
> --
> 2.7.4
> 
> 
> .
> 

Re: [PATCH v2 2/2] arm64: cacheinfo: add support to override cache levels via device tree

[Tan Xiaojun]

On 2017/1/13 2:29, Sudeep Holla wrote:
> The cache hierarchy can be identified through Cache Level ID(CLIDR)
> architected system register. However in some cases it will provide
> only the number of cache levels that are integrated into the processor
> itself. In other words, it can't provide any information about the
> caches that are external and/or transparent.
> 
> Some platforms require to export the information about all such external
> caches to the userspace applications via the sysfs interface.
> 
> This patch adds support to override the cache levels using device tree
> to take such external non-architected caches into account.
> 
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will.deacon@arm.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

Tested-by: Tan Xiaojun <tanxiaojun@huawei.com>

> ---
>  arch/arm64/kernel/cacheinfo.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/kernel/cacheinfo.c b/arch/arm64/kernel/cacheinfo.c
> index 9617301f76b5..3f2250fc391b 100644
> --- a/arch/arm64/kernel/cacheinfo.c
> +++ b/arch/arm64/kernel/cacheinfo.c
> @@ -84,7 +84,7 @@ static void ci_leaf_init(struct cacheinfo *this_leaf,
> 
>  static int __init_cache_level(unsigned int cpu)
>  {
> -	unsigned int ctype, level, leaves;
> +	unsigned int ctype, level, leaves, of_level;
>  	struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
> 
>  	for (level = 1, leaves = 0; level <= MAX_CACHE_LEVEL; level++) {
> @@ -97,6 +97,17 @@ static int __init_cache_level(unsigned int cpu)
>  		leaves += (ctype == CACHE_TYPE_SEPARATE) ? 2 : 1;
>  	}
> 
> +	of_level = of_find_last_cache_level(cpu);
> +	if (level < of_level) {
> +		/*
> +		 * some external caches not specified in CLIDR_EL1
> +		 * the information may be available in the device tree
> +		 * only unified external caches are considered here
> +		 */
> +		leaves += (of_level - level);
> +		level = of_level;
> +	}
> +
>  	this_cpu_ci->num_levels = level;
>  	this_cpu_ci->num_leaves = leaves;
>  	return 0;
> --
> 2.7.4
> 
> 
> .
> 

Re: [PATCH v2 2/2] arm64: cacheinfo: add support to override cache levels via device tree

[Sudeep Holla]

On 13/01/17 09:06, Tan Xiaojun wrote:
> On 2017/1/13 2:29, Sudeep Holla wrote:
>> The cache hierarchy can be identified through Cache Level ID(CLIDR)
>> architected system register. However in some cases it will provide
>> only the number of cache levels that are integrated into the processor
>> itself. In other words, it can't provide any information about the
>> caches that are external and/or transparent.
>>
>> Some platforms require to export the information about all such external
>> caches to the userspace applications via the sysfs interface.
>>
>> This patch adds support to override the cache levels using device tree
>> to take such external non-architected caches into account.
>>
>> Cc: Catalin Marinas <catalin.marinas@arm.com>
>> Cc: Will Deacon <will.deacon@arm.com>
>> Cc: Mark Rutland <mark.rutland@arm.com>
>> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
> 
> Tested-by: Tan Xiaojun <tanxiaojun@huawei.com>
> 

Thanks for testing.

-- 
Regards,
Sudeep

Re: [PATCH v2 1/2] of: base: add support to find the level of the last cache

[Rob Herring]

On Thu, Jan 12, 2017 at 12:29 PM, Sudeep Holla <sudeep.holla@arm.com> wrote:
> It is useful to have helper function just to get the number of cache
> levels for a given logical cpu. We can obtain the same by just checking
> the level at which the last cache is present. This patch adds support
> to find the level of the last cache for a given cpu.
>
> It will be used on ARM64 platform where the device tree provides the
> information for the additional non-architected/transparent/external
> last level caches that are not integrated with the processors.
>
> Suggested-by: Rob Herring <robh+dt@kernel.org>
> Cc: Rob Herring <robh+dt@kernel.org>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
> ---
>  drivers/of/base.c  | 27 +++++++++++++++++++++++++++
>  include/linux/of.h |  1 +
>  2 files changed, 28 insertions(+)
>
> v1->v2:
>         - Moved to using "cache-level" in the last level cache instead
>           of counting through all the nodes as suggested by Rob
>
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index d4bea3c797d6..c1128a077aea 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -25,6 +25,7 @@
>  #include <linux/cpu.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
> +#include <linux/of_device.h>
>  #include <linux/of_graph.h>
>  #include <linux/spinlock.h>
>  #include <linux/slab.h>
> @@ -2268,6 +2269,32 @@ struct device_node *of_find_next_cache_node(const struct device_node *np)
>  }
>
>  /**
> + * of_find_last_cache_level - Find the level at which the last cache is
> + *             present for the given logical cpu
> + *
> + * @cpu: cpu number(logical index) for which the last cache level is needed
> + *
> + * Returns the the level at which the last cache is present. It is exactly
> + * same as  the total number of cache levels for the given logical cpu.
> + */
> +int of_find_last_cache_level(unsigned int cpu)
> +{
> +       int cache_level = 0;
> +       struct device_node *prev = NULL, *np = of_cpu_device_node_get(cpu);
> +
> +       while (np) {
> +               prev = np;
> +               of_node_put(np);
> +               np = of_find_next_cache_node(np);
> +       }
> +
> +       if (prev)

Probably don't need this check. Otherwise,

Acked-by: Rob Herring <robh@kernel.org>

> +               of_property_read_u32(prev, "cache-level", &cache_level);
> +
> +       return cache_level;
> +}
> +
> +/**
>   * of_graph_parse_endpoint() - parse common endpoint node properties
>   * @node: pointer to endpoint device_node
>   * @endpoint: pointer to the OF endpoint data structure
> diff --git a/include/linux/of.h b/include/linux/of.h
> index d72f01009297..21e6323de0f3 100644
> --- a/include/linux/of.h
> +++ b/include/linux/of.h
> @@ -280,6 +280,7 @@ extern struct device_node *of_get_child_by_name(const struct device_node *node,
>
>  /* cache lookup */
>  extern struct device_node *of_find_next_cache_node(const struct device_node *);
> +extern int of_find_last_cache_level(unsigned int cpu);
>  extern struct device_node *of_find_node_with_property(
>         struct device_node *from, const char *prop_name);
>
> --
> 2.7.4
>

Re: [PATCH v2 1/2] of: base: add support to find the level of the last cache

[Sudeep Holla]

On 14/01/17 02:45, Rob Herring wrote:
> On Thu, Jan 12, 2017 at 12:29 PM, Sudeep Holla <sudeep.holla@arm.com> wrote:
>> It is useful to have helper function just to get the number of cache
>> levels for a given logical cpu. We can obtain the same by just checking
>> the level at which the last cache is present. This patch adds support
>> to find the level of the last cache for a given cpu.
>>
>> It will be used on ARM64 platform where the device tree provides the
>> information for the additional non-architected/transparent/external
>> last level caches that are not integrated with the processors.
>>
>> Suggested-by: Rob Herring <robh+dt@kernel.org>
>> Cc: Rob Herring <robh+dt@kernel.org>
>> Cc: Mark Rutland <mark.rutland@arm.com>
>> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
>> ---
>>  drivers/of/base.c  | 27 +++++++++++++++++++++++++++
>>  include/linux/of.h |  1 +
>>  2 files changed, 28 insertions(+)
>>
>> v1->v2:
>>         - Moved to using "cache-level" in the last level cache instead
>>           of counting through all the nodes as suggested by Rob
>>
>> diff --git a/drivers/of/base.c b/drivers/of/base.c
>> index d4bea3c797d6..c1128a077aea 100644
>> --- a/drivers/of/base.c
>> +++ b/drivers/of/base.c
>> @@ -25,6 +25,7 @@
>>  #include <linux/cpu.h>
>>  #include <linux/module.h>
>>  #include <linux/of.h>
>> +#include <linux/of_device.h>
>>  #include <linux/of_graph.h>
>>  #include <linux/spinlock.h>
>>  #include <linux/slab.h>
>> @@ -2268,6 +2269,32 @@ struct device_node *of_find_next_cache_node(const struct device_node *np)
>>  }
>>
>>  /**
>> + * of_find_last_cache_level - Find the level at which the last cache is
>> + *             present for the given logical cpu
>> + *
>> + * @cpu: cpu number(logical index) for which the last cache level is needed
>> + *
>> + * Returns the the level at which the last cache is present. It is exactly
>> + * same as  the total number of cache levels for the given logical cpu.
>> + */
>> +int of_find_last_cache_level(unsigned int cpu)
>> +{
>> +       int cache_level = 0;
>> +       struct device_node *prev = NULL, *np = of_cpu_device_node_get(cpu);
>> +
>> +       while (np) {
>> +               prev = np;
>> +               of_node_put(np);
>> +               np = of_find_next_cache_node(np);
>> +       }
>> +
>> +       if (prev)
> 
> Probably don't need this check. Otherwise,
> 
Sure I will drop the check.

> Acked-by: Rob Herring <robh@kernel.org>
> 

I assume you are fine taking this via arm64 tree. If not, let us know.

-- 
Regards,
Sudeep