USB: Add a sysfs file to show LTM capabilities.

USB 3.0 devices can optionally support Latency Tolerance Messaging
(LTM).  Add a new sysfs file in the device directory to show whether a
device is LTM capable.  This file will be present for both USB 2.0 and
USB 3.0 devices.

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/include/linux/usb.h b/include/linux/usb.h
index f29831bad235..f8506ed0f97b 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -636,6 +636,14 @@ extern void usb_unlocked_enable_lpm(struct usb_device *udev);
 extern int usb_disable_ltm(struct usb_device *udev);
 extern void usb_enable_ltm(struct usb_device *udev);
 
+static inline bool usb_device_supports_ltm(struct usb_device *udev)
+{
+        if (udev->speed != USB_SPEED_SUPER || !udev->bos || !udev->bos->ss_cap)
+                return false;
+        return udev->bos->ss_cap->bmAttributes & USB_LTM_SUPPORT;
+}
+
+
 /*-------------------------------------------------------------------------*/
 
 /* for drivers using iso endpoints */