PM: Add facility for advanced testing of async suspend/resume
Add configuration switch CONFIG_PM_ADVANCED_DEBUG for compiling in
extra PM debugging/testing code allowing one to access some
PM-related attributes of devices from the user space via sysfs.
If CONFIG_PM_ADVANCED_DEBUG is set, add sysfs attribute power/async
for every device allowing the user space to access the device's
power.async_suspend flag and modify it, if desired.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
diff --git a/drivers/base/power/sysfs.c b/drivers/base/power/sysfs.c
index c011ff1..86fd937 100644
--- a/drivers/base/power/sysfs.c
+++ b/drivers/base/power/sysfs.c
@@ -54,6 +54,24 @@
* wakeup events internally (unless they are disabled), keeping
* their hardware in low power modes whenever they're unused. This
* saves runtime power, without requiring system-wide sleep states.
+ *
+ * async - Report/change current async suspend setting for the device
+ *
+ * Asynchronous suspend and resume of the device during system-wide power
+ * state transitions can be enabled by writing "enabled" to this file.
+ * Analogously, if "disabled" is written to this file, the device will be
+ * suspended and resumed synchronously.
+ *
+ * All devices have one of the following two values for power/async:
+ *
+ * + "enabled\n" to permit the asynchronous suspend/resume of the device;
+ * + "disabled\n" to forbid it;
+ *
+ * NOTE: It generally is unsafe to permit the asynchronous suspend/resume
+ * of a device unless it is certain that all of the PM dependencies of the
+ * device are known to the PM core. However, for some devices this
+ * attribute is set to "enabled" by bus type code or device drivers and in
+ * that cases it should be safe to leave the default value.
*/
static const char enabled[] = "enabled";
@@ -125,12 +143,43 @@
static DEVICE_ATTR(wakeup, 0644, wake_show, wake_store);
+#ifdef CONFIG_PM_SLEEP_ADVANCED_DEBUG
+static ssize_t async_show(struct device *dev, struct device_attribute *attr,
+ char *buf)
+{
+ return sprintf(buf, "%s\n",
+ device_async_suspend_enabled(dev) ? enabled : disabled);
+}
+
+static ssize_t async_store(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t n)
+{
+ char *cp;
+ int len = n;
+
+ cp = memchr(buf, '\n', n);
+ if (cp)
+ len = cp - buf;
+ if (len == sizeof enabled - 1 && strncmp(buf, enabled, len) == 0)
+ device_enable_async_suspend(dev);
+ else if (len == sizeof disabled - 1 && strncmp(buf, disabled, len) == 0)
+ device_disable_async_suspend(dev);
+ else
+ return -EINVAL;
+ return n;
+}
+
+static DEVICE_ATTR(async, 0644, async_show, async_store);
+#endif /* CONFIG_PM_SLEEP_ADVANCED_DEBUG */
static struct attribute * power_attrs[] = {
#ifdef CONFIG_PM_RUNTIME
&dev_attr_control.attr,
#endif
&dev_attr_wakeup.attr,
+#ifdef CONFIG_PM_SLEEP_ADVANCED_DEBUG
+ &dev_attr_async.attr,
+#endif
NULL,
};
static struct attribute_group pm_attr_group = {