From 978224af2f8a22224b267b4bb9011fe793b70a74 Mon Sep 17 00:00:00 2001
From: Daniele Palmas <dnlplm@gmail.com>
Date: Thu, 19 Dec 2019 11:07:07 +0100
Subject: [PATCH] USB: serial: option: add ZLP support for 0x1bc7/0x9010

commit 2438c3a19dec5e98905fd3ffcc2f24716aceda6b upstream.

Telit FN980 flashing device 0x1bc7/0x9010 requires zero packet
to be sent if out data size is is equal to the endpoint max size.

Signed-off-by: Daniele Palmas <dnlplm@gmail.com>
[ johan: switch operands in conditional ]
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/drivers/usb/serial/option.c b/drivers/usb/serial/option.c
index fea09a3f491f..2d919d0e6e45 100644
--- a/drivers/usb/serial/option.c
+++ b/drivers/usb/serial/option.c
@@ -567,6 +567,9 @@ static void option_instat_callback(struct urb *urb);
 /* Interface must have two endpoints */
 #define NUMEP2		BIT(16)
 
+/* Device needs ZLP */
+#define ZLP		BIT(17)
+
 
 static const struct usb_device_id option_ids[] = {
 	{ USB_DEVICE(OPTION_VENDOR_ID, OPTION_PRODUCT_COLT) },
@@ -1198,6 +1201,8 @@ static const struct usb_device_id option_ids[] = {
 	  .driver_info = NCTRL(0) | RSVD(1) },
 	{ USB_DEVICE_INTERFACE_CLASS(TELIT_VENDOR_ID, 0x1901, 0xff),	/* Telit LN940 (MBIM) */
 	  .driver_info = NCTRL(0) },
+	{ USB_DEVICE(TELIT_VENDOR_ID, 0x9010),				/* Telit SBL FN980 flashing device */
+	  .driver_info = NCTRL(0) | ZLP },
 	{ USB_DEVICE_AND_INTERFACE_INFO(ZTE_VENDOR_ID, ZTE_PRODUCT_MF622, 0xff, 0xff, 0xff) }, /* ZTE WCDMA products */
 	{ USB_DEVICE_AND_INTERFACE_INFO(ZTE_VENDOR_ID, 0x0002, 0xff, 0xff, 0xff),
 	  .driver_info = RSVD(1) },
@@ -2099,6 +2104,9 @@ static int option_attach(struct usb_serial *serial)
 	if (!(device_flags & NCTRL(iface_desc->bInterfaceNumber)))
 		data->use_send_setup = 1;
 
+	if (device_flags & ZLP)
+		data->use_zlp = 1;
+
 	spin_lock_init(&data->susp_lock);
 
 	usb_set_serial_data(serial, data);
diff --git a/drivers/usb/serial/usb-wwan.h b/drivers/usb/serial/usb-wwan.h
index 1c120eaf4091..934e9361cf6b 100644
--- a/drivers/usb/serial/usb-wwan.h
+++ b/drivers/usb/serial/usb-wwan.h
@@ -38,6 +38,7 @@ struct usb_wwan_intf_private {
 	spinlock_t susp_lock;
 	unsigned int suspended:1;
 	unsigned int use_send_setup:1;
+	unsigned int use_zlp:1;
 	int in_flight;
 	unsigned int open_ports;
 	void *private;
diff --git a/drivers/usb/serial/usb_wwan.c b/drivers/usb/serial/usb_wwan.c
index 7e855c87e4f7..13be21aad2f4 100644
--- a/drivers/usb/serial/usb_wwan.c
+++ b/drivers/usb/serial/usb_wwan.c
@@ -461,6 +461,7 @@ static struct urb *usb_wwan_setup_urb(struct usb_serial_port *port,
 				      void (*callback) (struct urb *))
 {
 	struct usb_serial *serial = port->serial;
+	struct usb_wwan_intf_private *intfdata = usb_get_serial_data(serial);
 	struct urb *urb;
 
 	urb = usb_alloc_urb(0, GFP_KERNEL);	/* No ISO */
@@ -471,6 +472,9 @@ static struct urb *usb_wwan_setup_urb(struct usb_serial_port *port,
 			  usb_sndbulkpipe(serial->dev, endpoint) | dir,
 			  buf, len, callback, ctx);
 
+	if (intfdata->use_zlp && dir == USB_DIR_OUT)
+		urb->transfer_flags |= URB_ZERO_PACKET;
+
 	return urb;
 }
 
-- 
2.7.4