| Hans de Goede | 82aa038 | 2013-10-21 08:53:31 +0100 | [diff] [blame^] | 1 | #include <linux/usb.h> |
| 2 | #include <linux/usb/hcd.h> |
| 3 | |
| 4 | static int uas_is_interface(struct usb_host_interface *intf) |
| 5 | { |
| 6 | return (intf->desc.bInterfaceClass == USB_CLASS_MASS_STORAGE && |
| 7 | intf->desc.bInterfaceSubClass == USB_SC_SCSI && |
| 8 | intf->desc.bInterfaceProtocol == USB_PR_UAS); |
| 9 | } |
| 10 | |
| 11 | static int uas_isnt_supported(struct usb_device *udev) |
| 12 | { |
| 13 | struct usb_hcd *hcd = bus_to_hcd(udev->bus); |
| 14 | |
| 15 | dev_warn(&udev->dev, "The driver for the USB controller %s does not " |
| 16 | "support scatter-gather which is\n", |
| 17 | hcd->driver->description); |
| 18 | dev_warn(&udev->dev, "required by the UAS driver. Please try an" |
| 19 | "alternative USB controller if you wish to use UAS.\n"); |
| 20 | return -ENODEV; |
| 21 | } |
| 22 | |
| 23 | static int uas_find_uas_alt_setting(struct usb_interface *intf) |
| 24 | { |
| 25 | int i; |
| 26 | struct usb_device *udev = interface_to_usbdev(intf); |
| 27 | int sg_supported = udev->bus->sg_tablesize != 0; |
| 28 | |
| 29 | for (i = 0; i < intf->num_altsetting; i++) { |
| 30 | struct usb_host_interface *alt = &intf->altsetting[i]; |
| 31 | |
| 32 | if (uas_is_interface(alt)) { |
| 33 | if (!sg_supported) |
| 34 | return uas_isnt_supported(udev); |
| 35 | return alt->desc.bAlternateSetting; |
| 36 | } |
| 37 | } |
| 38 | |
| 39 | return -ENODEV; |
| 40 | } |