[PATCH 2/3] PM: add sysfs attributes for additional suspend/resume metrics

[Joshua Crofts <crofts@kernel.org>]

Add sysfs entries for additional suspend/resume statistics. These are
useful for investigating the behaviour of devices with PM runtime
enabled.

Signed-off-by: Joshua Crofts <crofts@kernel.org>
---
 Documentation/ABI/testing/sysfs-devices-power | 36 ++++++++++++
 drivers/base/power/sysfs.c                    | 81 +++++++++++++++++++++++++++
 2 files changed, 117 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-devices-power b/Documentation/ABI/testing/sysfs-devices-power
index 9bf7c8a267c58703a8a097ada1f12271271dbe98..03e5783d737120f98a1c88e5e53f56fe176484e5 100644
--- a/Documentation/ABI/testing/sysfs-devices-power
+++ b/Documentation/ABI/testing/sysfs-devices-power
@@ -284,6 +284,42 @@ Description:
 		Reports total time that the device has been suspended, in
 		milliseconds. Used for runtime PM statistics.
 
+What:           /sys/devices/.../power/runtime_resume_count
+Date:           Nov 2026
+Contact:        Joshua Crofts <crofts@kernel.org>
+Description:
+                Reports the total number of times the device entered a resume
+                state.
+
+What:           /sys/devices/.../power/runtime_suspend_count
+Date:           Nov 2026
+Contact:        Joshua Crofts <crofts@kernel.org>
+Description:
+                Reports the total number of times the device entered a suspended
+                state.
+
+What:           /sys/devices/.../power/runtime_last_suspended_time
+Date:           Nov 2026
+Contact:        Joshua Crofts <crofts@kernel.org>
+Description:
+                Reports the residency duration of the most recent suspended
+                state, in milliseconds.
+
+What:           /sys/devices/.../power/runtime_min_suspended_time
+Date:           Nov 2026
+Contact:        Joshua Crofts <crofts@kernel.org>
+Description:
+                Reports the shortest measured duration the device spent in
+                suspended mode, in milliseconds.
+
+What:           /sys/devices/.../power/runtime_max_suspended_time
+Date:           Nov 2026
+Contact:        Joshua Crofts <crofts@kernel.org>
+Description:
+                Reports the longest measured duration the device spent in
+                suspended mode, in milliseconds.
+
+
 What:		/sys/devices/.../power/runtime_usage
 Date:		Apr 2010
 Contact:	Dominik Brodowski <linux@dominikbrodowski.net>
diff --git a/drivers/base/power/sysfs.c b/drivers/base/power/sysfs.c
index 13b31a3adc77c0fe0a5c42fcf9b863dd5bc43088..7e5a186b33222d448b5caacaddbaf9913fe41a98 100644
--- a/drivers/base/power/sysfs.c
+++ b/drivers/base/power/sysfs.c
@@ -178,6 +178,82 @@ static ssize_t runtime_status_show(struct device *dev,
 
 static DEVICE_ATTR_RO(runtime_status);
 
+static ssize_t runtime_resume_count_show(struct device *dev,
+					 struct device_attribute *attr,
+					 char *buf)
+{
+	u64 count;
+
+	spin_lock_irq(&dev->power.lock);
+	count = dev->power.resume_count;
+	spin_unlock_irq(&dev->power.lock);
+
+	return sysfs_emit(buf, "%llu\n", count);
+}
+static DEVICE_ATTR_RO(runtime_resume_count);
+
+static ssize_t runtime_suspend_count_show(struct device *dev,
+					  struct device_attribute *attr,
+					  char *buf)
+{
+	u64 count;
+
+	spin_lock_irq(&dev->power.lock);
+	count = dev->power.suspend_count;
+	spin_unlock_irq(&dev->power.lock);
+
+	return sysfs_emit(buf, "%llu\n", count);
+}
+static DEVICE_ATTR_RO(runtime_suspend_count);
+
+static ssize_t runtime_last_suspended_time_show(struct device *dev,
+						struct device_attribute *attr,
+						char *buf)
+{
+	u64 tmp;
+
+	spin_lock_irq(&dev->power.lock);
+	tmp = dev->power.last_suspended_time;
+	spin_unlock_irq(&dev->power.lock);
+
+	do_div(tmp, NSEC_PER_MSEC);
+
+	return sysfs_emit(buf, "%llu\n", tmp);
+}
+static DEVICE_ATTR_RO(runtime_last_suspended_time);
+
+static ssize_t runtime_min_suspended_time_show(struct device *dev,
+					       struct device_attribute *attr,
+					       char *buf)
+{
+	u64 tmp;
+
+	spin_lock_irq(&dev->power.lock);
+	tmp = dev->power.min_suspended_time;
+	spin_unlock_irq(&dev->power.lock);
+
+	do_div(tmp, NSEC_PER_MSEC);
+
+	return sysfs_emit(buf, "%llu\n", tmp);
+}
+static DEVICE_ATTR_RO(runtime_min_suspended_time);
+
+static ssize_t runtime_max_suspended_time_show(struct device *dev,
+					       struct device_attribute *attr,
+					       char *buf)
+{
+	u64 tmp;
+
+	spin_lock_irq(&dev->power.lock);
+	tmp = dev->power.max_suspended_time;
+	spin_unlock_irq(&dev->power.lock);
+
+	do_div(tmp, NSEC_PER_MSEC);
+
+	return sysfs_emit(buf, "%llu\n", tmp);
+}
+static DEVICE_ATTR_RO(runtime_max_suspended_time);
+
 static ssize_t autosuspend_delay_ms_show(struct device *dev,
 					 struct device_attribute *attr,
 					 char *buf)
@@ -649,6 +725,11 @@ static struct attribute *runtime_attrs[] = {
 	&dev_attr_runtime_suspended_time.attr,
 	&dev_attr_runtime_active_time.attr,
 	&dev_attr_autosuspend_delay_ms.attr,
+	&dev_attr_runtime_resume_count.attr,
+	&dev_attr_runtime_suspend_count.attr,
+	&dev_attr_runtime_last_suspended_time.attr,
+	&dev_attr_runtime_min_suspended_time.attr,
+	&dev_attr_runtime_max_suspended_time.attr,
 #ifdef CONFIG_PM_ADVANCED_DEBUG
 	&dev_attr_runtime_usage.attr,
 	&dev_attr_runtime_active_kids.attr,

-- 
2.47.3