[PATCH RFC 1/4] driver/perf: Add identifier sysfs file for CMN

[Jing Zhang]

To allow userspace to identify the specific implementation of the device,
add an "identifier" sysfs file.

The perf tool can match the arm CMN metric through the identifier.

Signed-off-by: Jing Zhang <renyu.zj@xxxxxxxxxxxxxxxxx>
---
 drivers/perf/arm-cmn.c | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/drivers/perf/arm-cmn.c b/drivers/perf/arm-cmn.c
index c968986..0c138ad 100644
--- a/drivers/perf/arm-cmn.c
+++ b/drivers/perf/arm-cmn.c
@@ -1168,10 +1168,53 @@ static ssize_t arm_cmn_cpumask_show(struct device *dev,
 	.attrs = 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));
+	if (cmn->model == CMN700) {
+		return sysfs_emit(buf, "%s\n", "CMN700");
+	}
+	else if (cmn->model == CMN650) {
+		return sysfs_emit(buf, "%s\n", "CMN650");
+	}
+	else if (cmn->model == CMN600) {
+		return sysfs_emit(buf, "%s\n", "CMN600");
+	}
+	else if (cmn->model == CI700) {
+		return sysfs_emit(buf, "%s\n", "CI700");
+	}
+	return sysfs_emit(buf, "%s\n", "UNKNOWN");
+}
+
+static umode_t arm_cmn_identifier_attr_visible(struct kobject *kobj,
+		struct attribute *attr, int n)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct arm_cmn *cmn = to_cmn(dev_get_drvdata(dev));
+	if (cmn->model <= 0)
+		return 0;
+	return attr->mode;
+};
+
+static struct device_attribute arm_cmn_identifier_attr =
+__ATTR(identifier, 0444, arm_cmn_identifier_show, NULL);
+
+static struct attribute *arm_cmn_identifier_attrs[] = {
+	&arm_cmn_identifier_attr.attr,
+	NULL,
+};
+
+static struct attribute_group arm_cmn_identifier_attr_group = {
+	.attrs = arm_cmn_identifier_attrs,
+	.is_visible = arm_cmn_identifier_attr_visible,
+};
+
 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_identifier_attr_group,
 	NULL
 };
 
-- 
1.8.3.1