1 files changed, 96 insertions, 0 deletions
diff --git a/drivers/usb/storage/uas-detect.h b/drivers/usb/storage/uas-detect.h
new file mode 100644
index 000000000000..bb05b984d5f6
--- /dev/null
+++ b/drivers/usb/storage/uas-detect.h
@@ -0,0 +1,96 @@
+#include <linux/usb.h>
+#include <linux/usb/hcd.h>
+#include "usb.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;
+}
+
+static int uas_find_endpoints(struct usb_host_interface *alt,
+			      struct usb_host_endpoint *eps[])
+{
+	struct usb_host_endpoint *endpoint = alt->endpoint;
+	unsigned i, n_endpoints = alt->desc.bNumEndpoints;
+
+	for (i = 0; i < n_endpoints; i++) {
+		unsigned char *extra = endpoint[i].extra;
+		int len = endpoint[i].extralen;
+		while (len >= 3) {
+			if (extra[1] == USB_DT_PIPE_USAGE) {
+				unsigned pipe_id = extra[2];
+				if (pipe_id > 0 && pipe_id < 5)
+					eps[pipe_id - 1] = &endpoint[i];
+				break;
+			}
+			len -= extra[0];
+			extra += extra[0];
+		}
+	}
+
+	if (!eps[0] || !eps[1] || !eps[2] || !eps[3])
+		return -ENODEV;
+
+	return 0;
+}
+
+static int uas_use_uas_driver(struct usb_interface *intf,
+			      const struct usb_device_id *id)
+{
+	struct usb_host_endpoint *eps[4] = { };
+	struct usb_device *udev = interface_to_usbdev(intf);
+	struct usb_hcd *hcd = bus_to_hcd(udev->bus);
+	unsigned long flags = id->driver_info;
+	int r, alt;
+
+	usb_stor_adjust_quirks(udev, &flags);
+
+	if (flags & US_FL_IGNORE_UAS)
+		return 0;
+
+	if (udev->speed >= USB_SPEED_SUPER && !hcd->can_do_streams)
+		return 0;
+
+	alt = uas_find_uas_alt_setting(intf);
+	if (alt < 0)
+		return 0;
+
+	r = uas_find_endpoints(&intf->altsetting[alt], eps);
+	if (r < 0)
+		return 0;
+
+	return 1;
+}