usb: gadget: u_serial: convert into a module

Every user of u_serial has now to select the U_SERIAL symbol instead of
including the file.
There is one limition with this: ports and and gs_tty_driver are global
variables in u_serial. Since all users share them, there can be only one
user loaded at a time i.e. either g_serial or g_nokia.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/Kconfig

@@ -503,6 +503,9 @@ config USB_LIBCOMPOSITE
 config USB_F_SS_LB
 	tristate
 
+config USB_U_SERIAL
+	tristate
+
 choice
 	tristate "USB Gadget Drivers"
 	default USB_ETH
@@ -754,6 +757,7 @@ config USB_GADGET_TARGET
 
 config USB_G_SERIAL
 	tristate "Serial Gadget (with CDC ACM and CDC OBEX support)"
+	select USB_U_SERIAL
 	select USB_LIBCOMPOSITE
 	help
 	  The Serial Gadget talks to the Linux-USB generic serial driver.
@@ -807,6 +811,7 @@ config USB_CDC_COMPOSITE
 	tristate "CDC Composite Device (Ethernet and ACM)"
 	depends on NET
 	select USB_LIBCOMPOSITE
+	select USB_U_SERIAL
 	help
 	  This driver provides two functions in one configuration:
 	  a CDC Ethernet (ECM) link, and a CDC ACM (serial port) link.
@@ -822,6 +827,7 @@ config USB_G_NOKIA
 	tristate "Nokia composite gadget"
 	depends on PHONET
 	select USB_LIBCOMPOSITE
+	select USB_U_SERIAL
 	help
 	  The Nokia composite gadget provides support for acm, obex
 	  and phonet in only one composite gadget driver.
@@ -833,6 +839,7 @@ config USB_G_ACM_MS
 	tristate "CDC Composite Device (ACM and mass storage)"
 	depends on BLOCK
 	select USB_LIBCOMPOSITE
+	select USB_U_SERIAL
 	help
 	  This driver provides two functions in one configuration:
 	  a mass storage, and a CDC ACM (serial port) link.
@@ -845,6 +852,7 @@ config USB_G_MULTI
 	depends on BLOCK && NET
 	select USB_G_MULTI_CDC if !USB_G_MULTI_RNDIS
 	select USB_LIBCOMPOSITE
+	select USB_U_SERIAL
 	help
 	  The Multifunction Composite Gadget provides Ethernet (RNDIS
 	  and/or CDC Ethernet), mass storage and ACM serial link
@@ -920,6 +928,7 @@ config USB_G_DBGP_PRINTK
 
 config USB_G_DBGP_SERIAL
 	depends on USB_G_DBGP
+	select USB_U_SERIAL
 	bool "serial"
 	help
 	  Userland can interact using /dev/ttyGSxxx.

drivers/usb/gadget/Makefile

@@ -78,3 +78,4 @@ obj-$(CONFIG_USB_GADGET_TARGET)	+= tcm_usb_gadget.o
 # USB Functions
 f_ss_lb-y			:= f_loopback.o f_sourcesink.o
 obj-$(CONFIG_USB_F_SS_LB)	+= f_ss_lb.o
+obj-$(CONFIG_USB_U_SERIAL)	+= u_serial.o

drivers/usb/gadget/acm_ms.c

@@ -41,7 +41,6 @@
  * a "gcc --combine ... part1.c part2.c part3.c ... " build would.
  */
 
-#include "u_serial.c"
 #include "f_acm.c"
 #include "f_mass_storage.c"
 

drivers/usb/gadget/cdc2.c

@@ -43,7 +43,6 @@ USB_GADGET_COMPOSITE_OPTIONS();
  * a "gcc --combine ... part1.c part2.c part3.c ... " build would.
  */
 
-#include "u_serial.c"
 #include "f_acm.c"
 #include "f_ecm.c"
 #include "u_ether.c"

drivers/usb/gadget/dbgp.c

@@ -13,9 +13,7 @@
 #include <linux/usb/ch9.h>
 #include <linux/usb/gadget.h>
 
-#ifdef CONFIG_USB_G_DBGP_SERIAL
-#include "u_serial.c"
-#endif
+#include "u_serial.h"
 
 #define DRIVER_VENDOR_ID	0x0525 /* NetChip */
 #define DRIVER_PRODUCT_ID	0xc0de /* undefined */

drivers/usb/gadget/multi.c

@@ -42,7 +42,6 @@ MODULE_LICENSE("GPL");
  */
 #include "f_mass_storage.c"
 
-#include "u_serial.c"
 #include "f_acm.c"
 
 #include "f_ecm.c"

drivers/usb/gadget/nokia.c

@@ -37,7 +37,6 @@
  * the runtime footprint, and giving us at least some parts of what
  * a "gcc --combine ... part1.c part2.c part3.c ... " build would.
  */
-#include "u_serial.c"
 #include "f_acm.c"
 #include "f_ecm.c"
 #include "f_obex.c"

drivers/usb/gadget/serial.c

@@ -39,7 +39,6 @@
 #include "f_acm.c"
 #include "f_obex.c"
 #include "f_serial.c"
-#include "u_serial.c"
 
 /*-------------------------------------------------------------------------*/
 USB_GADGET_COMPOSITE_OPTIONS();

drivers/usb/gadget/u_serial.c

@@ -26,6 +26,7 @@
 #include <linux/tty_flip.h>
 #include <linux/slab.h>
 #include <linux/export.h>
+#include <linux/module.h>
 
 #include "u_serial.h"
 
@@ -309,6 +310,7 @@ gs_alloc_req(struct usb_ep *ep, unsigned len, gfp_t kmalloc_flags)
 
 	return req;
 }
+EXPORT_SYMBOL_GPL(gs_alloc_req);
 
 /*
  * gs_free_req
@@ -320,6 +322,7 @@ void gs_free_req(struct usb_ep *ep, struct usb_request *req)
 	kfree(req->buf);
 	usb_ep_free_request(ep, req);
 }
+EXPORT_SYMBOL_GPL(gs_free_req);
 
 /*
  * gs_send_packet
@@ -1081,6 +1084,9 @@ int gserial_setup(struct usb_gadget *g, unsigned count)
 	if (count == 0 || count > N_PORTS)
 		return -EINVAL;
 
+	if (gs_tty_driver)
+		return -EBUSY;
+
 	gs_tty_driver = alloc_tty_driver(count);
 	if (!gs_tty_driver)
 		return -ENOMEM;
@@ -1153,6 +1159,7 @@ int gserial_setup(struct usb_gadget *g, unsigned count)
 	gs_tty_driver = NULL;
 	return status;
 }
+EXPORT_SYMBOL_GPL(gserial_setup);
 
 static int gs_closed(struct gs_port *port)
 {
@@ -1213,6 +1220,7 @@ void gserial_cleanup(void)
 
 	pr_debug("%s: cleaned up ttyGS* support\n", __func__);
 }
+EXPORT_SYMBOL_GPL(gserial_cleanup);
 
 /**
  * gserial_connect - notify TTY I/O glue that USB link is active
@@ -1292,7 +1300,7 @@ int gserial_connect(struct gserial *gser, u8 port_num)
 	gser->in->driver_data = NULL;
 	return status;
 }
-
+EXPORT_SYMBOL_GPL(gserial_connect);
 /**
  * gserial_disconnect - notify TTY I/O glue that USB link is inactive
  * @gser: the function, on which gserial_connect() was called
@@ -1347,3 +1355,6 @@ void gserial_disconnect(struct gserial *gser)
 
 	spin_unlock_irqrestore(&port->port_lock, flags);
 }
+EXPORT_SYMBOL_GPL(gserial_disconnect);
+
+MODULE_LICENSE("GPL");