Subject: [QUESTION] Arm64: Query L3 cache info via DT

From: [email-masked] (Tan Xiaojun)
Date: Tue, 10 Jan 2017 16:50:02 +0800

I add this patch, and test in Hisilicon D02/D03. It can work well.

I'm sorry to reply so late. I took some time to debug, because I am not familiar with the code.

> +	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
> +		 */
> +		level = of_level;
> +		leaves += (of_level - level);

The above two lines need to exchange the location.

> +	}

PS: I will test the other scenes, the next step.

Thanks.
Xiaojun.

----------------------------------------------------------------------------
D02:
root at genericarmv8:~# cat /sys/devices/system/cpu/cpu0/cache/index3/size
16384K
root at genericarmv8:~# cat /sys/devices/system/cpu/cpu0/cache/index3/number_of_sets
4096
root at genericarmv8:~# cat /sys/devices/system/cpu/cpu0/cache/index3/coherency_line_size
64
root at genericarmv8:~# cat /sys/devices/system/cpu/cpu0/cache/index3/level
3
root at genericarmv8:~# cat /sys/devices/system/cpu/cpu0/cache/index3/shared_cpu_list
0-15
root at genericarmv8:~# cat /sys/devices/system/cpu/cpu0/cache/index3/shared_cpu_map
ffff

----------------------------------------------------------------------------
D02 (some data may be not accurate):
diff --git a/arch/arm64/boot/dts/hisilicon/hip05.dtsi b/arch/arm64/boot/dts/hisilicon/hip05.dtsi
index 4b472a3..aac18c2 100644
--- a/arch/arm64/boot/dts/hisilicon/hip05.dtsi
+++ b/arch/arm64/boot/dts/hisilicon/hip05.dtsi
@@ -215,18 +215,30 @@

                cluster0_l2: l2-cache0 {
                        compatible = "cache";
+                       next-level-cache = <&die0_l3c>;
                };

                cluster1_l2: l2-cache1 {
                        compatible = "cache";
+                       next-level-cache = <&die0_l3c>;
                };

                cluster2_l2: l2-cache2 {
                        compatible = "cache";
+                       next-level-cache = <&die0_l3c>;
                };

                cluster3_l2: l2-cache3 {
                        compatible = "cache";
+                       next-level-cache = <&die0_l3c>;
+               };
+
+               die0_l3c: l3-cache {
+                       compatible = "cache";
+                       cache-size = <16777216>;
+                       cache-line-size = <64>;
+                       cache-block-size = <16>;
+                       cache-sets = <4096>;
                };
        };

On 2017/1/4 19:47, Sudeep Holla wrote:
> 
> Hi Tan,
> 
> On 28/12/16 03:42, Tan Xiaojun wrote:
>> Hi.
>>
>> I saw you discussed how to achieve querying cache information and
>> tend to implement the external ones(like L3 cache) via DT a few
>> months ago.
>>
>> http://lists.infradead.org/pipermail/linux-arm-kernel/2016-February/405399.html
>>
>>  Are these implementations progressing? Forgive me to take the
>> liberty to ask, we care about this thing.
>>
> 
> Yes the support to override the cache properties for DT was added in v4.10
> 
> However, it still depends on the the sysreg to get the total levels of
> caches supported in the system. You may need to tweak a bit around that
> to support what you need.
> 
>> If you've already implemented some codes, we can help with testing
>> (in Hisilicon D02, D03, D05) after you send it to the mail-list.
>>
> 
> Sure, that would help.
> 
>> We can try our best to help if there is any difficulty.
> 
> OK, you can start trying the patch below :). It's not even compile
> tested, so you make have to make some changes necessary. I just wanted
> to put my thoughts here. Make sure all the L3 cacheinfo is present in DT.
> 
> Regards,
> Sudeep
> 
> 
> --
> 
> diff --git i/arch/arm64/kernel/cacheinfo.c w/arch/arm64/kernel/cacheinfo.c
> index 9617301f76b5..88fbcd368104 100644
> --- i/arch/arm64/kernel/cacheinfo.c
> +++ w/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_count_cache_levels(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
> +		 */
> +		level = of_level;
> +		leaves += (of_level - level);
> +	}
> +
>  	this_cpu_ci->num_levels = level;
>  	this_cpu_ci->num_leaves = leaves;
>  	return 0;
> diff --git i/drivers/of/base.c w/drivers/of/base.c
> index d4bea3c797d6..8007f3b06cb8 100644
> --- i/drivers/of/base.c
> +++ w/drivers/of/base.c
> @@ -2267,6 +2267,20 @@ struct device_node *of_find_next_cache_node(const
> struct device_node *np)
>  	return NULL;
>  }
> 
> +int of_count_cache_levels(unsigned int cpu)
> +{
> +	int level = 0;
> +	struct device *cpu_dev = get_cpu_device(cpu);
> +	struct device_node *np = cpu_dev->of_node;
> +
> +	while (np) {
> +		level++;
> +		np = of_find_next_cache_node(np);
> +	}
> +
> +	return level;
> +}
> +
>  /**
>   * of_graph_parse_endpoint() - parse common endpoint node properties
>   * @node: pointer to endpoint device_node
> diff --git i/include/linux/of.h w/include/linux/of.h
> index d72f01009297..c8597ae71ff3 100644
> --- i/include/linux/of.h
> +++ w/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_count_cache_levels(unsigned int cpu);
>  extern struct device_node *of_find_node_with_property(
>  	struct device_node *from, const char *prop_name);
> 
> 
> .
>