[PATCH 2/4] pseries/drc-info: Search DRC properties for CPU indexes

Nathan Fontenot nfont at linux.vnet.ibm.com
Fri Jul 28 04:25:23 AEST 2017


On 07/27/2017 11:10 AM, Michael Bringmann wrote:
> 
> pseries/drc-info: Provide parallel routines to convert between
> drc_index and CPU numbers at runtime, using the older device-tree
> properties ("ibm,drc-indexes", "ibm,drc-names", "ibm,drc-types"
> and "ibm,drc-power-domains"), or the new property "ibm,drc-info".
> 
> Signed-off-by: Michael Bringmann <mwb at linux.vnet.ibm.com>
> ---
>  arch/powerpc/include/asm/prom.h                 |    7 +
>  arch/powerpc/platforms/pseries/of_helpers.c     |   79 ++++++++++++
>  arch/powerpc/platforms/pseries/pseries_energy.c |  150 +++++++++++++++++++----
>  3 files changed, 210 insertions(+), 26 deletions(-)
> ---
> Changes in V2:
>   -- Minor changes to integrate to latest 4.13 code
> 
> diff --git a/arch/powerpc/include/asm/prom.h b/arch/powerpc/include/asm/prom.h
> index 4fb02cc..d469d7c 100644
> --- a/arch/powerpc/include/asm/prom.h
> +++ b/arch/powerpc/include/asm/prom.h
> @@ -96,6 +96,13 @@ struct of_drconf_cell {
>  #define DRCONF_MEM_AI_INVALID	0x00000040
>  #define DRCONF_MEM_RESERVED	0x00000080
> 
> +extern int of_one_drc_info(struct property **prop, void **curval,
> +			char **dtype, char **dname,
> +			u32 *drc_index_start_p,
> +			u32 *num_sequential_elems_p,
> +			u32 *sequential_inc_p,
> +			u32 *last_drc_index_p);
> +
>  /*
>   * There are two methods for telling firmware what our capabilities are.
>   * Newer machines have an "ibm,client-architecture-support" method on the
> diff --git a/arch/powerpc/platforms/pseries/of_helpers.c b/arch/powerpc/platforms/pseries/of_helpers.c
> index 2798933..1d59939 100644
> --- a/arch/powerpc/platforms/pseries/of_helpers.c
> +++ b/arch/powerpc/platforms/pseries/of_helpers.c
> @@ -36,3 +36,82 @@ struct device_node *pseries_of_derive_parent(const char *path)
>  		kfree(parent_path);
>  	return parent ? parent : ERR_PTR(-EINVAL);
>  }
> +
> +
> +/* Helper Routines to convert between drc_index to cpu numbers */
> +
> +int of_one_drc_info(struct property **prop, void **curval,
> +			char **dtype, char **dname,
> +			u32 *drc_index_start_p,
> +			u32 *num_sequential_elems_p,
> +			u32 *sequential_inc_p,
> +			u32 *last_drc_index_p)
> +{
> +	char *drc_type, *drc_name_prefix;
> +	u32 drc_index_start, num_sequential_elems, dummy;
> +	u32 sequential_inc, last_drc_index;
> +	const char *p;
> +	const __be32 *p2;
> +
> +	drc_index_start = num_sequential_elems = 0;
> +	sequential_inc = last_drc_index = 0;
> +
> +	/* Get drc-type:encode-string */
> +	p = drc_type = (*curval);
> +	p = of_prop_next_string(*prop, p);
> +	if (!p)
> +		return -EINVAL;
> +
> +	/* Get drc-name-prefix:encode-string */
> +	drc_name_prefix = (char *)p;
> +	p = of_prop_next_string(*prop, p);
> +	if (!p)
> +		return -EINVAL;
> +
> +	/* Get drc-index-start:encode-int */
> +	p2 = (const __be32 *)p;
> +	p2 = of_prop_next_u32(*prop, p2, &drc_index_start);
> +	if (!p2)
> +		return -EINVAL;
> +
> +	/* Get/skip drc-name-suffix-start:encode-int */

Why are we skipping the drc name suffix start value? It seems this
would make the routine unusable for anyone wanting to get drc-name
values.

> +	p2 = of_prop_next_u32(*prop, p2, &dummy);
> +	if (!p)

shouldn't this be checking p2?

> +		return -EINVAL;
> +
> +	/* Get number-sequential-elements:encode-int */
> +	p2 = of_prop_next_u32(*prop, p2, &num_sequential_elems);
> +	if (!p2)
> +		return -EINVAL;
> +
> +	/* Get sequential-increment:encode-int */
> +	p2 = of_prop_next_u32(*prop, p2, &sequential_inc);
> +	if (!p2)
> +		return -EINVAL;
> +
> +	/* Get/skip drc-power-domain:encode-int */

Same for power-domain, why skip it?

I don't think any parts of the kernel are currently
looking at this piece of the DRC information, but if we are
going to have a routine to return all the data for a drc-info
block shouldn't it return all of it?

Would it be easier if the routine were to return a drc_info struct with
pointers to the string values and int values read into it?

> +	p2 = of_prop_next_u32(*prop, p2, &dummy);
> +	if (!p2)
> +		return -EINVAL;
> +
> +	/* Should now know end of current entry */
> +	(*curval) = (void *)p2;
> +	last_drc_index = drc_index_start +
> +			((num_sequential_elems-1)*sequential_inc);
> +
> +	if (dtype)
> +		*dtype = drc_type;
> +	if (dname)
> +		*dname = drc_name_prefix;
> +	if (drc_index_start_p)
> +		*drc_index_start_p = drc_index_start;
> +	if (num_sequential_elems_p)
> +		*num_sequential_elems_p = num_sequential_elems;
> +	if (sequential_inc_p)
> +		*sequential_inc_p = sequential_inc;
> +	if (last_drc_index_p)
> +		*last_drc_index_p = last_drc_index;
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(of_one_drc_info);
> diff --git a/arch/powerpc/platforms/pseries/pseries_energy.c b/arch/powerpc/platforms/pseries/pseries_energy.c
> index 164a13d..865c2af 100644
> --- a/arch/powerpc/platforms/pseries/pseries_energy.c
> +++ b/arch/powerpc/platforms/pseries/pseries_energy.c
> @@ -22,6 +22,7 @@
>  #include <asm/page.h>
>  #include <asm/hvcall.h>
>  #include <asm/firmware.h>
> +#include <asm/prom.h>
> 
> 
>  #define MODULE_VERS "1.0"
> @@ -38,7 +39,6 @@
>  static u32 cpu_to_drc_index(int cpu)
>  {
>  	struct device_node *dn = NULL;
> -	const int *indexes;
>  	int i;
>  	int rc = 1;
>  	u32 ret = 0;
> @@ -46,18 +46,65 @@ static u32 cpu_to_drc_index(int cpu)
>  	dn = of_find_node_by_path("/cpus");
>  	if (dn == NULL)
>  		goto err;
> -	indexes = of_get_property(dn, "ibm,drc-indexes", NULL);
> -	if (indexes == NULL)
> -		goto err_of_node_put;
> +
>  	/* Convert logical cpu number to core number */
>  	i = cpu_core_index_of_thread(cpu);
> -	/*
> -	 * The first element indexes[0] is the number of drc_indexes
> -	 * returned in the list.  Hence i+1 will get the drc_index
> -	 * corresponding to core number i.
> -	 */
> -	WARN_ON(i > indexes[0]);
> -	ret = indexes[i + 1];
> +
> +	if (firmware_has_feature(FW_FEATURE_DRC_INFO)) {
> +		struct property *info = NULL;
> +		int j, check_val = i;

Why use check_val here? it seems a bit confusing.

I think perhaps renaming 'i' to thread_index  and using that everywhere
may help the readability.

> +		u32 num_set_entries;
> +		u32 drc_index_start = 0;
> +		u32 last_drc_index = 0;
> +		u32 num_sequential_elems = 0;
> +		u32 sequential_inc = 0;
> +		char *dtype;
> +		char *dname;
> +		void *value;
> +
> +		info = of_find_property(dn, "ibm,drc-info", NULL);
> +		if (info == NULL)
> +			goto err_of_node_put;
> +
> +		value = info->value;
> +		value = (void *)of_prop_next_u32(info, value, &num_set_entries);
> +		if (!value)
> +			goto err_of_node_put;
> +
> +		for (j = 0; j < num_set_entries; j++) {
> +
> +			of_one_drc_info(&info, &value, &dtype, &dname,
> +					&drc_index_start,
> +					&num_sequential_elems,
> +					&sequential_inc, &last_drc_index);
> +			if (strcmp(dtype, "CPU"))

Perhaps use strncmp() here.

> +				goto err;
> +
> +			if (check_val < last_drc_index)

So, check_val here is just the thread_index for the cpu we are looking for.
I think this value will likely always be less than last_drc_index. On systems
I have always seen the drc-index values for CPUs start at 0x10000000 and
increment from there.

If there is ever more than one set of drc-info blocks in the drc-info
property this check would not be valid.

> +				break;
> +
> +			WARN_ON(((check_val-drc_index_start)%
> +					sequential_inc) != 0);
> +		}
> +		WARN_ON((num_sequential_elems == 0) || (sequential_inc == 0));
> +
> +		ret = last_drc_index + (check_val*sequential_inc);

Shouldn't this be drc_index_start?

> +	} else {
> +		const __be32 *indexes;
> +
> +		indexes = of_get_property(dn, "ibm,drc-indexes", NULL);
> +		if (indexes == NULL)
> +			goto err_of_node_put;
> +
> +		/*
> +		 * The first element indexes[0] is the number of drc_indexes
> +		 * returned in the list.  Hence i+1 will get the drc_index
> +		 * corresponding to core number i.
> +		 */
> +		WARN_ON(i > indexes[0]);
> +		ret = indexes[i + 1];
> +	}
> +
>  	rc = 0;
> 
>  err_of_node_put:
> @@ -72,34 +119,85 @@ static int drc_index_to_cpu(u32 drc_index)
>  {
>  	struct device_node *dn = NULL;
>  	const int *indexes;
> -	int i, cpu = 0;
> +	int thread = 0, cpu = 0;
>  	int rc = 1;
> 
>  	dn = of_find_node_by_path("/cpus");
>  	if (dn == NULL)
>  		goto err;
> -	indexes = of_get_property(dn, "ibm,drc-indexes", NULL);
> -	if (indexes == NULL)
> -		goto err_of_node_put;
> -	/*
> -	 * First element in the array is the number of drc_indexes
> -	 * returned.  Search through the list to find the matching
> -	 * drc_index and get the core number
> -	 */
> -	for (i = 0; i < indexes[0]; i++) {
> -		if (indexes[i + 1] == drc_index)
> +
> +	if (firmware_has_feature(FW_FEATURE_DRC_INFO)) {
> +		struct property *info = NULL;
> +		int j;
> +		u32 num_set_entries;
> +		u32 drc_index_start = 0;
> +		u32 last_drc_index = 0;
> +		u32 num_sequential_elems = 0;
> +		u32 sequential_inc = 0;
> +		char *dtype, *dname;
> +		void *value;
> +
> +		info = of_find_property(dn, "ibm,drc-info", NULL);
> +		if (info == NULL)
> +			goto err_of_node_put;
> +
> +		value = info->value;
> +		value = (void *)of_prop_next_u32(info, value, &num_set_entries);
> +		if (!value)
> +			goto err_of_node_put;
> +
> +		for (j = 0; j < num_set_entries; j++) {
> +
> +			of_one_drc_info(&info, &value, &dtype, &dname,
> +					&drc_index_start,
> +					&num_sequential_elems,
> +					&sequential_inc, &last_drc_index);
> +			if (strcmp(dtype, "CPU"))
> +				goto err;
> +
> +			WARN_ON(drc_index < drc_index_start);
> +			WARN_ON(((drc_index-drc_index_start)%
> +					sequential_inc) != 0);
> +
> +			if (drc_index > last_drc_index) {
> +				cpu += ((last_drc_index-drc_index_start)/
> +					sequential_inc);

Could we just use num_sequential_elems here?

				cpu += num_sequential_elems;


-Nathan

> +				continue;
> +			} else {
> +				cpu += ((drc_index-drc_index_start)/
> +					sequential_inc);
> +			}
> +
> +			thread = cpu_first_thread_of_core(cpu);
> +			rc = 0;
>  			break;
> +		}
> +	} else {
> +		unsigned long int i;
> +
> +		indexes = of_get_property(dn, "ibm,drc-indexes", NULL);
> +		if (indexes == NULL)
> +			goto err_of_node_put;
> +		/*
> +		 * First element in the array is the number of drc_indexes
> +		 * returned.  Search through the list to find the matching
> +		 * drc_index and get the core number
> +		 */
> +		for (i = 0; i < indexes[0]; i++) {
> +			if (indexes[i + 1] == drc_index)
> +				break;
> +		}
> +		/* Convert core number to logical cpu number */
> +		thread = cpu_first_thread_of_core(i);
> +		rc = 0;
>  	}
> -	/* Convert core number to logical cpu number */
> -	cpu = cpu_first_thread_of_core(i);
> -	rc = 0;
> 
>  err_of_node_put:
>  	of_node_put(dn);
>  err:
>  	if (rc)
>  		printk(KERN_WARNING "drc_index_to_cpu(%d) failed", drc_index);
> -	return cpu;
> +	return thread;
>  }
> 
>  /*
> 



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