uas: Reset device on reboot

Some BIOS-es will hang on reboot when an uas device is attached and left in
uas mode on reboot.

This commit adds a shutdown handler which on reboot puts the device back into
usb-storage mode, fixing the hang on reboot on these systems.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>

drivers/usb/storage/uas.c

@@ -54,6 +54,7 @@ struct uas_dev_info {
 	unsigned use_streams:1;
 	unsigned uas_sense_old:1;
 	unsigned running_task:1;
+	unsigned shutdown:1;
 	struct scsi_cmnd *cmnd;
 	spinlock_t lock;
 	struct work_struct work;
@@ -1011,6 +1012,7 @@ static int uas_probe(struct usb_interface *intf, const struct usb_device_id *id)
 	devinfo->udev = udev;
 	devinfo->resetting = 0;
 	devinfo->running_task = 0;
+	devinfo->shutdown = 0;
 	init_usb_anchor(&devinfo->cmd_urbs);
 	init_usb_anchor(&devinfo->sense_urbs);
 	init_usb_anchor(&devinfo->data_urbs);
@@ -1053,6 +1055,9 @@ static int uas_pre_reset(struct usb_interface *intf)
 	struct uas_dev_info *devinfo = (void *)shost->hostdata[0];
 	unsigned long flags;
 
+	if (devinfo->shutdown)
+		return 0;
+
 	/* Block new requests */
 	spin_lock_irqsave(shost->host_lock, flags);
 	scsi_block_requests(shost);
@@ -1076,6 +1081,9 @@ static int uas_post_reset(struct usb_interface *intf)
 	struct uas_dev_info *devinfo = (void *)shost->hostdata[0];
 	unsigned long flags;
 
+	if (devinfo->shutdown)
+		return 0;
+
 	if (uas_configure_endpoints(devinfo) != 0) {
 		shost_printk(KERN_ERR, shost,
 			     "%s: alloc streams error after reset", __func__);
@@ -1147,6 +1155,27 @@ static void uas_disconnect(struct usb_interface *intf)
 	kfree(devinfo);
 }
 
+/*
+ * Put the device back in usb-storage mode on shutdown, as some BIOS-es
+ * hang on reboot when the device is still in uas mode. Note the reset is
+ * necessary as some devices won't revert to usb-storage mode without it.
+ */
+static void uas_shutdown(struct device *dev)
+{
+	struct usb_interface *intf = to_usb_interface(dev);
+	struct usb_device *udev = interface_to_usbdev(intf);
+	struct Scsi_Host *shost = usb_get_intfdata(intf);
+	struct uas_dev_info *devinfo = (void *)shost->hostdata[0];
+
+	if (system_state != SYSTEM_RESTART)
+		return;
+
+	devinfo->shutdown = 1;
+	uas_free_streams(devinfo);
+	usb_set_interface(udev, intf->altsetting[0].desc.bInterfaceNumber, 0);
+	usb_reset_device(udev);
+}
+
 static struct usb_driver uas_driver = {
 	.name = "uas",
 	.probe = uas_probe,
@@ -1156,6 +1185,7 @@ static struct usb_driver uas_driver = {
 	.suspend = uas_suspend,
 	.resume = uas_resume,
 	.reset_resume = uas_reset_resume,
+	.drvwrap.driver.shutdown = uas_shutdown,
 	.id_table = uas_usb_ids,
 };