usb/acpi: Use ACPI methods to power off ports.

Upcoming Intel systems will have an ACPI method to control whether a USB
port can be completely powered off.  The implication of powering off a
USB port is that the device and host sees a physical disconnect, and
subsequent port connections and remote wakeups will be lost.

Add a new function, usb_acpi_power_manageable(), that can be used to
find whether the usb port has ACPI power resources that can be used to
power on and off the port on these machines. Also add a new function
called usb_acpi_set_power_state() that controls the port power via these
ACPI methods.

When the USB core calls into the xHCI hub driver to power off a port,
check whether the port can be completely powered off via this new ACPI
mechanism.  If so, call into these new ACPI methods.  Also use the ACPI
methods when the USB core asks to power on a port.

Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/include/linux/usb.h b/include/linux/usb.h
index e0084a1fa37f..07915a32fb9d 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -602,6 +602,16 @@ extern int usb_lock_device_for_reset(struct usb_device *udev,
 extern int usb_reset_device(struct usb_device *dev);
 extern void usb_queue_reset_device(struct usb_interface *dev);
 
+#ifdef CONFIG_ACPI
+extern int usb_acpi_set_power_state(struct usb_device *hdev, int index,
+        bool enable);
+extern bool usb_acpi_power_manageable(struct usb_device *hdev, int index);
+#else
+static inline int usb_acpi_set_power_state(struct usb_device *hdev, int index,
+        bool enable) { return 0; }
+static inline bool usb_acpi_power_manageable(struct usb_device *hdev, int index)
+        { return true; }
+#endif
 
 /* USB autosuspend and autoresume */
 #ifdef CONFIG_USB_SUSPEND