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#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;
}
static int uas_use_uas_driver(struct usb_interface *intf,
const struct usb_device_id *id)
{
unsigned long flags = id->driver_info;
if (flags & US_FL_IGNORE_UAS)
return 0;
return uas_find_uas_alt_setting(intf) >= 0;
}
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