usb: Bind devices to ACPI devices when possible

Built-in USB devices will typically have a representation in the system
ACPI tables. Add support for binding the two together so the USB code can
make use of the associated methods.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 60 insertions, 0 deletions

diff --git a/drivers/usb/core/usb-acpi.c b/drivers/usb/core/usb-acpi.c
new file mode 100644
index 000000000000..cab5cb7c256c
--- /dev/null
+++ b/drivers/usb/core/usb-acpi.c
@@ -0,0 +1,60 @@
+/*
+ * USB-ACPI glue code
+ *
+ * Copyright 2012 Red Hat <mjg@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation, version 2.
+ *
+ */
+#include <linux/module.h>
+#include <linux/usb.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/acpi.h>
+#include <linux/pci.h>
+#include <acpi/acpi_bus.h>
+
+#include "usb.h"
+
+static int usb_acpi_find_device(struct device *dev, acpi_handle *handle)
+{
+	struct usb_device *udev;
+	struct device *parent;
+	acpi_handle *parent_handle;
+
+	if (!is_usb_device(dev))
+		return -ENODEV;
+
+	udev = to_usb_device(dev);
+	parent = dev->parent;
+	parent_handle = DEVICE_ACPI_HANDLE(parent);
+
+	if (!parent_handle)
+		return -ENODEV;
+
+	*handle = acpi_get_child(parent_handle, udev->portnum);
+
+	if (!*handle)
+		return -ENODEV;
+
+	return 0;
+}
+
+static struct acpi_bus_type usb_acpi_bus = {
+	.bus = &usb_bus_type,
+	.find_bridge = NULL,
+	.find_device = usb_acpi_find_device,
+};
+
+int usb_acpi_register(void)
+{
+	return register_acpi_bus_type(&usb_acpi_bus);
+}
+
+void usb_acpi_unregister(void)
+{
+	unregister_acpi_bus_type(&usb_acpi_bus);
+}