Re: [PATCH v3 3/7] drivers: base: cacheinfo: arm64: Add support for ACPI based firmware tables

[Lorenzo Pieralisi]

On Thu, Oct 12, 2017 at 02:48:52PM -0500, Jeremy Linton wrote:
> The /sys cache entries should support ACPI/PPTT generated cache
> topology information. Lets detect ACPI systems and call
> an arch specific cache_setup_acpi() routine to update the hardware
> probed cache topology.
> 
> For arm64, if ACPI is enabled, determine the max number of cache
> levels and populate them using a PPTT table if one is available.
> 
> Signed-off-by: Jeremy Linton <jeremy.linton@xxxxxxx>
> ---
>  arch/arm64/kernel/cacheinfo.c | 23 ++++++++++++++++++-----
>  drivers/acpi/pptt.c           |  1 +
>  drivers/base/cacheinfo.c      | 17 +++++++++++------
>  include/linux/cacheinfo.h     | 11 +++++++++--
>  4 files changed, 39 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/arm64/kernel/cacheinfo.c b/arch/arm64/kernel/cacheinfo.c
> index 380f2e2fbed5..2e2cf0d312ba 100644
> --- a/arch/arm64/kernel/cacheinfo.c
> +++ b/arch/arm64/kernel/cacheinfo.c
> @@ -17,6 +17,7 @@
>   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
>   */
>  
> +#include <linux/acpi.h>
>  #include <linux/cacheinfo.h>
>  #include <linux/of.h>
>  
> @@ -44,9 +45,17 @@ static void ci_leaf_init(struct cacheinfo *this_leaf,
>  	this_leaf->type = type;
>  }
>  
> +#ifndef CONFIG_ACPI
> +int acpi_find_last_cache_level(unsigned int cpu)
> +{
> +	/*ACPI kernels should be built with PPTT support*/
> +	return 0;
> +}
> +#endif
> +
>  static int __init_cache_level(unsigned int cpu)
>  {
> -	unsigned int ctype, level, leaves, of_level;
> +	unsigned int ctype, level, leaves, fw_level;
>  	struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
>  
>  	for (level = 1, leaves = 0; level <= MAX_CACHE_LEVEL; level++) {
> @@ -59,15 +68,19 @@ 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) {
> +	if (acpi_disabled)
> +		fw_level = of_find_last_cache_level(cpu);
> +	else
> +		fw_level = acpi_find_last_cache_level(cpu);
> +
> +	if (level < fw_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;
> +		leaves += (fw_level - level);
> +		level = fw_level;
>  	}
>  
>  	this_cpu_ci->num_levels = level;
> diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c
> index c86715fed4a7..b5c6de37e328 100644
> --- a/drivers/acpi/pptt.c
> +++ b/drivers/acpi/pptt.c
> @@ -355,6 +355,7 @@ static void update_cache_properties(struct cacheinfo *this_leaf,
>  				    struct acpi_pptt_cache *found_cache,
>  				    struct acpi_pptt_processor *cpu_node)
>  {
> +	this_leaf->firmware_node = cpu_node;

This pointer comes from an ACPI static table mapping that happens
to be permanent so it should be safe given that the mapping is carried
out at device_initcall (ie cache_setup_acpi()) but it is not that
obvious. More to it below.

>  	if (found_cache->flags & ACPI_PPTT_SIZE_PROPERTY_VALID)
>  		this_leaf->size = found_cache->size;
>  	if (found_cache->flags & ACPI_PPTT_LINE_SIZE_VALID)
> diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c
> index eb3af2739537..8eca279e50d1 100644
> --- a/drivers/base/cacheinfo.c
> +++ b/drivers/base/cacheinfo.c
> @@ -86,7 +86,7 @@ static int cache_setup_of_node(unsigned int cpu)
>  static inline bool cache_leaves_are_shared(struct cacheinfo *this_leaf,
>  					   struct cacheinfo *sib_leaf)
>  {
> -	return sib_leaf->of_node == this_leaf->of_node;
> +	return sib_leaf->firmware_node == this_leaf->firmware_node;
>  }
>  
>  /* OF properties to query for a given cache type */
> @@ -215,6 +215,11 @@ static inline bool cache_leaves_are_shared(struct cacheinfo *this_leaf,
>  }
>  #endif
>  
> +int __weak cache_setup_acpi(unsigned int cpu)
> +{
> +	return -ENOTSUPP;
> +}
> +
>  static int cache_shared_cpu_map_setup(unsigned int cpu)
>  {
>  	struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
> @@ -225,11 +230,11 @@ static int cache_shared_cpu_map_setup(unsigned int cpu)
>  	if (this_cpu_ci->cpu_map_populated)
>  		return 0;
>  
> -	if (of_have_populated_dt())
> +	if (!acpi_disabled)
> +		ret = cache_setup_acpi(cpu);
> +	else if (of_have_populated_dt())
>  		ret = cache_setup_of_node(cpu);
> -	else if (!acpi_disabled)
> -		/* No cache property/hierarchy support yet in ACPI */
> -		ret = -ENOTSUPP;
> +
>  	if (ret)
>  		return ret;
>  
> @@ -286,7 +291,7 @@ static void cache_shared_cpu_map_remove(unsigned int cpu)
>  
>  static void cache_override_properties(unsigned int cpu)
>  {
> -	if (of_have_populated_dt())
> +	if (acpi_disabled && of_have_populated_dt())
>  		return cache_of_override_properties(cpu);
>  }
>  
> diff --git a/include/linux/cacheinfo.h b/include/linux/cacheinfo.h
> index 6a524bf6a06d..d1e9b8e01981 100644
> --- a/include/linux/cacheinfo.h
> +++ b/include/linux/cacheinfo.h
> @@ -36,6 +36,9 @@ enum cache_type {
>   * @of_node: if devicetree is used, this represents either the cpu node in
>   *	case there's no explicit cache node or the cache node itself in the
>   *	device tree
> + * @firmware_node: Shared with of_node. When not using DT, this may contain
> + *	pointers to other firmware based values. Particularly ACPI/PPTT
> + *	unique values.
>   * @disable_sysfs: indicates whether this node is visible to the user via
>   *	sysfs or not
>   * @priv: pointer to any private data structure specific to particular
> @@ -64,8 +67,10 @@ struct cacheinfo {
>  #define CACHE_ALLOCATE_POLICY_MASK	\
>  	(CACHE_READ_ALLOCATE | CACHE_WRITE_ALLOCATE)
>  #define CACHE_ID		BIT(4)
> -
> -	struct device_node *of_node;
> +	union {
> +		struct device_node *of_node;
> +		void *firmware_node;
> +	};

How about turning of_node into a struct fwnode_handle* (and allocate
one for each PPTT cache node - acpi_static_fwnode - to have the
ACPI counterpart) ?

It will make more churn given that that pointer is just used to
carry out a pointer comparison but it's also a bit more elegant.

Lorenzo

>  	bool disable_sysfs;
>  	void *priv;
>  };
> @@ -98,6 +103,8 @@ int func(unsigned int cpu)					\
>  struct cpu_cacheinfo *get_cpu_cacheinfo(unsigned int cpu);
>  int init_cache_level(unsigned int cpu);
>  int populate_cache_leaves(unsigned int cpu);
> +int cache_setup_acpi(unsigned int cpu);
> +int acpi_find_last_cache_level(unsigned int cpu);
>  
>  const struct attribute_group *cache_get_priv_group(struct cacheinfo *this_leaf);
>  
> -- 
> 2.13.5
>