Re: [PATCH 2/2] perf/arm-cmn: Add sysfs identifier

[Jing Zhang]

在 2023/6/13 上午1:16, Robin Murphy 写道:
> Expose a sysfs identifier encapsulating the CMN part number and revision
> so that jevents can narrow down a fundamental set of possible events for
> calculating metrics. Configuration-dependent aspects - such as whether a
> given node type is present, and/or a given node ID is valid - are still
> not covered, and in general it's hard to see how userspace could handle
> them, so we won't be removing any data or validation logic from the
> driver any time soon, but at least it's a step in a useful direction.
> 
> Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx>
> ---
>  drivers/perf/arm-cmn.c | 20 ++++++++++++++++----
>  1 file changed, 16 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/perf/arm-cmn.c b/drivers/perf/arm-cmn.c
> index 8cf4ed932950..088dc5c690a4 100644
> --- a/drivers/perf/arm-cmn.c
> +++ b/drivers/perf/arm-cmn.c
> @@ -1199,19 +1199,31 @@ static ssize_t arm_cmn_cpumask_show(struct device *dev,
>  static struct device_attribute arm_cmn_cpumask_attr =
>  		__ATTR(cpumask, 0444, arm_cmn_cpumask_show, NULL);
>  
> -static struct attribute *arm_cmn_cpumask_attrs[] = {
> +static ssize_t arm_cmn_identifier_show(struct device *dev,
> +				       struct device_attribute *attr, char *buf)
> +{
> +	struct arm_cmn *cmn = to_cmn(dev_get_drvdata(dev));
> +
> +	return sysfs_emit(buf, "%03x%02x\n", cmn->part, cmn->rev);
> +}
> +
> +static struct device_attribute arm_cmn_identifier_attr =
> +		__ATTR(identifier, 0444, arm_cmn_identifier_show, NULL);
> +
> +static struct attribute *arm_cmn_other_attrs[] = {
>  	&arm_cmn_cpumask_attr.attr,
> +	&arm_cmn_identifier_attr.attr,
>  	NULL,
>  };
>  
> -static const struct attribute_group arm_cmn_cpumask_attr_group = {
> -	.attrs = arm_cmn_cpumask_attrs,
> +static const struct attribute_group arm_cmn_other_attrs_group = {
> +	.attrs = arm_cmn_other_attrs,
>  };
>  
>  static const struct attribute_group *arm_cmn_attr_groups[] = {
>  	&arm_cmn_event_attrs_group,
>  	&arm_cmn_format_attrs_group,
> -	&arm_cmn_cpumask_attr_group,
> +	&arm_cmn_other_attrs_group,
>  	NULL
>  };
>  


Tested-by: Jing Zhang <renyu.zj@xxxxxxxxxxxxxxxxx>

Thanks,
Jing