USB: Export if an interface driver supports autosuspend.

Create a new sysfs file per interface named supports_autosuspend.  This
file returns true if an interface driver's .supports_autosuspend flag is
set.  It also returns true if the interface is unclaimed (since the USB
core will autosuspend a device if an interface is not claimed).

This new sysfs file will be useful for user space scripts to test whether
a USB device correctly auto-suspends.

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: Oliver Neukum <oliver@neukum.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb
index 11a3c16..df6c8a0 100644 (file)
--- a/Documentation/ABI/testing/sysfs-bus-usb
+++ b/Documentation/ABI/testing/sysfs-bus-usb
@@ -85,3 +85,19 @@ Description:
 Users:
                PowerTOP <power@bughost.org>
                http://www.lesswatts.org/projects/powertop/
+
+What:          /sys/bus/usb/device/<busnum>-<devnum>...:<config num>-<interface num>/supports_autosuspend
+Date:          January 2008
+KernelVersion: 2.6.27
+Contact:       Sarah Sharp <sarah.a.sharp@intel.com>
+Description:
+               When read, this file returns 1 if the interface driver
+               for this interface supports autosuspend.  It also
+               returns 1 if no driver has claimed this interface, as an
+               unclaimed interface will not stop the device from being
+               autosuspended if all other interface drivers are idle.
+               The file returns 0 if autosuspend support has not been
+               added to the driver.
+Users:
+               USB PM tool
+               git://git.moblin.org/users/sarah/usb-pm-tool/

diff --git a/drivers/usb/core/sysfs.c b/drivers/usb/core/sysfs.c
index 5e1f5d5..f66fba1 100644 (file)
--- a/drivers/usb/core/sysfs.c
+++ b/drivers/usb/core/sysfs.c
@@ -743,6 +743,29 @@ static ssize_t show_modalias(struct device *dev,
 }
 static DEVICE_ATTR(modalias, S_IRUGO, show_modalias, NULL);
 
+static ssize_t show_supports_autosuspend(struct device *dev,
+               struct device_attribute *attr, char *buf)
+{
+       struct usb_interface *intf;
+       struct usb_device *udev;
+       int ret;
+
+       intf = to_usb_interface(dev);
+       udev = interface_to_usbdev(intf);
+
+       usb_lock_device(udev);
+       /* Devices will be autosuspended even when an interface isn't claimed */
+       if (!intf->dev.driver ||
+                       to_usb_driver(intf->dev.driver)->supports_autosuspend)
+               ret = sprintf(buf, "%u\n", 1);
+       else
+               ret = sprintf(buf, "%u\n", 0);
+       usb_unlock_device(udev);
+
+       return ret;
+}
+static DEVICE_ATTR(supports_autosuspend, S_IRUGO, show_supports_autosuspend, NULL);
+
 static struct attribute *intf_attrs[] = {
        &dev_attr_bInterfaceNumber.attr,
        &dev_attr_bAlternateSetting.attr,
@@ -751,6 +774,7 @@ static struct attribute *intf_attrs[] = {
        &dev_attr_bInterfaceSubClass.attr,
        &dev_attr_bInterfaceProtocol.attr,
        &dev_attr_modalias.attr,
+       &dev_attr_supports_autosuspend.attr,
        NULL,
 };
 static struct attribute_group intf_attr_grp = {