USB: fix suspend support for usblp

this implements suspend support for usblp. According to the CUPS people
ENODEV will make CUPS retry the job. Thus it is returned in the runtime
case. My printer survives suspend/resume cycles with it.
Signed-off-by: Oliver Neukum <oliver@neukum.name>
Signed-off-by: Vojtech Pavlik <vojtech@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/class/usblp.c

@@ -154,6 +154,7 @@ struct usblp {
 	unsigned char		used;			/* True if open */
 	unsigned char		present;		/* True if not disconnected */
 	unsigned char		bidir;			/* interface is bidirectional */
+	unsigned char		sleeping;		/* interface is suspended */
 	unsigned char		*device_id_string;	/* IEEE 1284 DEVICE ID string (ptr) */
 							/* first 2 bytes are (big-endian) length */
 };
@@ -183,6 +184,7 @@ static void usblp_dump(struct usblp *usblp) {
 	dbg("quirks=%d", usblp->quirks);
 	dbg("used=%d", usblp->used);
 	dbg("bidir=%d", usblp->bidir);
+	dbg("sleeping=%d", usblp->sleeping);
 	dbg("device_id_string=\"%s\"",
 		usblp->device_id_string ?
 			usblp->device_id_string + 2 :
@@ -338,6 +340,20 @@ static int usblp_check_status(struct usblp *usblp, int err)
 	return newerr;
 }
 
+static int handle_bidir (struct usblp *usblp)
+{
+	if (usblp->bidir && usblp->used && !usblp->sleeping) {
+		usblp->readcount = 0;
+		usblp->readurb->dev = usblp->dev;
+		if (usb_submit_urb(usblp->readurb, GFP_KERNEL) < 0) {
+			usblp->used = 0;
+			return -EIO;
+		}
+	}
+
+	return 0;
+}
+
 /*
  * File op functions.
  */
@@ -390,14 +406,9 @@ static int usblp_open(struct inode *inode, struct file *file)
 	usblp->writeurb->status = 0;
 	usblp->readurb->status = 0;
 
-	if (usblp->bidir) {
-		usblp->readcount = 0;
-		usblp->readurb->dev = usblp->dev;
-		if (usb_submit_urb(usblp->readurb, GFP_KERNEL) < 0) {
-			retval = -EIO;
-			usblp->used = 0;
-			file->private_data = NULL;
-		}
+	if (handle_bidir(usblp) < 0) {
+		file->private_data = NULL;
+		retval = -EIO;
 	}
 out:
 	mutex_unlock (&usblp_mutex);
@@ -460,6 +471,11 @@ static long usblp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 		goto done;
 	}
 
+	if (usblp->sleeping) {
+		retval = -ENODEV;
+		goto done;
+	}
+
 	dbg("usblp_ioctl: cmd=0x%x (%c nr=%d len=%d dir=%d)", cmd, _IOC_TYPE(cmd),
 		_IOC_NR(cmd), _IOC_SIZE(cmd), _IOC_DIR(cmd) );
 
@@ -658,6 +674,11 @@ static ssize_t usblp_write(struct file *file, const char __user *buffer, size_t
 			return -ENODEV;
 		}
 
+		if (usblp->sleeping) {
+			up (&usblp->sem);
+			return writecount ? writecount : -ENODEV;
+		}
+
 		if (usblp->writeurb->status != 0) {
 			if (usblp->quirks & USBLP_QUIRK_BIDIR) {
 				if (!usblp->wcomplete)
@@ -749,6 +770,11 @@ static ssize_t usblp_read(struct file *file, char __user *buffer, size_t count,
 		goto done;
 	}
 
+	if (usblp->sleeping) {
+		count = -ENODEV;
+		goto done;
+	}
+
 	if (usblp->readurb->status) {
 		err("usblp%d: error %d reading from printer",
 			usblp->minor, usblp->readurb->status);
@@ -1167,6 +1193,41 @@ static void usblp_disconnect(struct usb_interface *intf)
 	mutex_unlock (&usblp_mutex);
 }
 
+static int usblp_suspend (struct usb_interface *intf, pm_message_t message)
+{
+	struct usblp *usblp = usb_get_intfdata (intf);
+
+	/* this races against normal access and open */
+	mutex_lock (&usblp_mutex);
+	down (&usblp->sem);
+	/* we take no more IO */
+	usblp->sleeping = 1;
+	/* we wait for anything printing */
+	wait_event (usblp->wait, usblp->wcomplete || !usblp->present);
+	usblp_unlink_urbs(usblp);
+	up (&usblp->sem);
+	mutex_unlock (&usblp_mutex);
+
+	return 0;
+}
+
+static int usblp_resume (struct usb_interface *intf)
+{
+	struct usblp *usblp = usb_get_intfdata (intf);
+	int r;
+
+	mutex_lock (&usblp_mutex);
+	down (&usblp->sem);
+
+	usblp->sleeping = 0;
+	r = handle_bidir (usblp);
+
+	up (&usblp->sem);
+	mutex_unlock (&usblp_mutex);
+
+	return r;
+}
+
 static struct usb_device_id usblp_ids [] = {
 	{ USB_DEVICE_INFO(7, 1, 1) },
 	{ USB_DEVICE_INFO(7, 1, 2) },
@@ -1183,6 +1244,8 @@ static struct usb_driver usblp_driver = {
 	.name =		"usblp",
 	.probe =	usblp_probe,
 	.disconnect =	usblp_disconnect,
+	.suspend =	usblp_suspend,
+	.resume =	usblp_resume,
 	.id_table =	usblp_ids,
 };