uas: Move uas detect code to uas-detect.h
This is a preparation patch for teaching usb-storage to not bind to
uas devices.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
diff --git a/drivers/usb/storage/uas-detect.h b/drivers/usb/storage/uas-detect.h
new file mode 100644
index 0000000..28101c7
--- /dev/null
+++ b/drivers/usb/storage/uas-detect.h
@@ -0,0 +1,40 @@
+#include <linux/usb.h>
+#include <linux/usb/hcd.h>
+
+static int uas_is_interface(struct usb_host_interface *intf)
+{
+ return (intf->desc.bInterfaceClass == USB_CLASS_MASS_STORAGE &&
+ intf->desc.bInterfaceSubClass == USB_SC_SCSI &&
+ intf->desc.bInterfaceProtocol == USB_PR_UAS);
+}
+
+static int uas_isnt_supported(struct usb_device *udev)
+{
+ struct usb_hcd *hcd = bus_to_hcd(udev->bus);
+
+ dev_warn(&udev->dev, "The driver for the USB controller %s does not "
+ "support scatter-gather which is\n",
+ hcd->driver->description);
+ dev_warn(&udev->dev, "required by the UAS driver. Please try an"
+ "alternative USB controller if you wish to use UAS.\n");
+ return -ENODEV;
+}
+
+static int uas_find_uas_alt_setting(struct usb_interface *intf)
+{
+ int i;
+ struct usb_device *udev = interface_to_usbdev(intf);
+ int sg_supported = udev->bus->sg_tablesize != 0;
+
+ for (i = 0; i < intf->num_altsetting; i++) {
+ struct usb_host_interface *alt = &intf->altsetting[i];
+
+ if (uas_is_interface(alt)) {
+ if (!sg_supported)
+ return uas_isnt_supported(udev);
+ return alt->desc.bAlternateSetting;
+ }
+ }
+
+ return -ENODEV;
+}