PM / Runtime: Add sysfs switch for disabling device run-time PM

[safe/jmp/linux-2.6] / drivers / base / power / sysfs.c

diff --git a/drivers/base/power/sysfs.c b/drivers/base/power/sysfs.c
index 596aeec..c011ff1 100644 (file)
--- a/drivers/base/power/sysfs.c
+++ b/drivers/base/power/sysfs.c
@@ -4,9 +4,25 @@
 
 #include <linux/device.h>
 #include <linux/string.h>
+#include <linux/pm_runtime.h>
 #include "power.h"
 
 /*
+ *     control - Report/change current runtime PM setting of the device
+ *
+ *     Runtime power management of a device can be blocked with the help of
+ *     this attribute.  All devices have one of the following two values for
+ *     the power/control file:
+ *
+ *      + "auto\n" to allow the device to be power managed at run time;
+ *      + "on\n" to prevent the device from being power managed at run time;
+ *
+ *     The default for all devices is "auto", which means that devices may be
+ *     subject to automatic power management, depending on their drivers.
+ *     Changing this attribute to "on" prevents the driver from power managing
+ *     the device at run time.  Doing that while the device is suspended causes
+ *     it to be woken up.
+ *
  *     wakeup - Report/change current wakeup option for device
  *
  *     Some devices support "wakeup" events, which are hardware signals
@@ -43,6 +59,38 @@
 static const char enabled[] = "enabled";
 static const char disabled[] = "disabled";
 
+#ifdef CONFIG_PM_RUNTIME
+static const char ctrl_auto[] = "auto";
+static const char ctrl_on[] = "on";
+
+static ssize_t control_show(struct device *dev, struct device_attribute *attr,
+                           char *buf)
+{
+       return sprintf(buf, "%s\n",
+                               dev->power.runtime_auto ? ctrl_auto : ctrl_on);
+}
+
+static ssize_t control_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 ctrl_auto - 1 && strncmp(buf, ctrl_auto, len) == 0)
+               pm_runtime_allow(dev);
+       else if (len == sizeof ctrl_on - 1 && strncmp(buf, ctrl_on, len) == 0)
+               pm_runtime_forbid(dev);
+       else
+               return -EINVAL;
+       return n;
+}
+
+static DEVICE_ATTR(control, 0644, control_show, control_store);
+#endif
+
 static ssize_t
 wake_show(struct device * dev, struct device_attribute *attr, char * buf)
 {
@@ -79,6 +127,9 @@ static DEVICE_ATTR(wakeup, 0644, wake_show, wake_store);
 
 
 static struct attribute * power_attrs[] = {
+#ifdef CONFIG_PM_RUNTIME
+       &dev_attr_control.attr,
+#endif
        &dev_attr_wakeup.attr,
        NULL,
 };