usb: gadget: convert source sink and loopback to new function interface

This patch converts the f_sourcesink and f_loopback file to the USB-function
module. Both functions shares a few common utility functions which are
currently implemented in g_zero.c itself. This patch moves the common
code into the sourcesink file and creates one module out of the the two
functions (source sink and loop back).
The g_zero gadget is function specific to source sink and loop back to
set a few options. This Symbol dependency enforces a modul load right
now.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/Kconfig

@@ -500,6 +500,9 @@ config USB_LIBCOMPOSITE
 	tristate
 	depends on USB_GADGET
 
+config USB_F_SS_LB
+	tristate
+
 choice
 	tristate "USB Gadget Drivers"
 	default USB_ETH
@@ -524,6 +527,7 @@ choice
 config USB_ZERO
 	tristate "Gadget Zero (DEVELOPMENT)"
 	select USB_LIBCOMPOSITE
+	select USB_F_SS_LB
 	help
 	  Gadget Zero is a two-configuration device.  It either sinks and
 	  sources bulk data; or it loops back a configurable number of

drivers/usb/gadget/Makefile

@@ -74,3 +74,7 @@ obj-$(CONFIG_USB_G_WEBCAM)	+= g_webcam.o
 obj-$(CONFIG_USB_G_NCM)		+= g_ncm.o
 obj-$(CONFIG_USB_G_ACM_MS)	+= g_acm_ms.o
 obj-$(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

drivers/usb/gadget/f_loopback.c

@@ -15,10 +15,11 @@
 #include <linux/slab.h>
 #include <linux/kernel.h>
 #include <linux/device.h>
+#include <linux/module.h>
+#include <linux/err.h>
+#include <linux/usb/composite.h>
 
 #include "g_zero.h"
-#include "gadget_chips.h"
-
 
 /*
  * LOOPBACK FUNCTION ... a testing vehicle for USB peripherals,
@@ -44,9 +45,8 @@ static inline struct f_loopback *func_to_loop(struct usb_function *f)
 	return container_of(f, struct f_loopback, function);
 }
 
-static unsigned qlen = 32;
-module_param(qlen, uint, 0);
-MODULE_PARM_DESC(qlenn, "depth of loopback queue");
+static unsigned qlen;
+static unsigned buflen;
 
 /*-------------------------------------------------------------------------*/
 
@@ -171,8 +171,7 @@ static struct usb_gadget_strings *loopback_strings[] = {
 
 /*-------------------------------------------------------------------------*/
 
-static int __init
-loopback_bind(struct usb_configuration *c, struct usb_function *f)
+static int loopback_bind(struct usb_configuration *c, struct usb_function *f)
 {
 	struct usb_composite_dev *cdev = c->cdev;
 	struct f_loopback	*loop = func_to_loop(f);
@@ -229,8 +228,7 @@ autoconf_fail:
 	return 0;
 }
 
-static void
-loopback_unbind(struct usb_configuration *c, struct usb_function *f)
+static void lb_free_func(struct usb_function *f)
 {
 	usb_free_all_descriptors(f);
 	kfree(func_to_loop(f));
@@ -372,25 +370,64 @@ static void loopback_disable(struct usb_function *f)
 	disable_loopback(loop);
 }
 
-/*-------------------------------------------------------------------------*/
-
-static int __init loopback_bind_config(struct usb_configuration *c)
+static struct usb_function *loopback_alloc(struct usb_function_instance *fi)
 {
 	struct f_loopback	*loop;
-	int			status;
+	struct f_lb_opts	*lb_opts;
 
 	loop = kzalloc(sizeof *loop, GFP_KERNEL);
 	if (!loop)
-		return -ENOMEM;
+		return ERR_PTR(-ENOMEM);
+
+	lb_opts = container_of(fi, struct f_lb_opts, func_inst);
+	buflen = lb_opts->bulk_buflen;
+	qlen = lb_opts->qlen;
+	if (!qlen)
+		qlen = 32;
 
 	loop->function.name = "loopback";
 	loop->function.bind = loopback_bind;
-	loop->function.unbind = loopback_unbind;
 	loop->function.set_alt = loopback_set_alt;
 	loop->function.disable = loopback_disable;
+	loop->function.strings = loopback_strings;
+
+	loop->function.free_func = lb_free_func;
+
+	return &loop->function;
+}
+
+static void lb_free_instance(struct usb_function_instance *fi)
+{
+	struct f_lb_opts *lb_opts;
 
-	status = usb_add_function(c, &loop->function);
-	if (status)
-		kfree(loop);
-	return status;
+	lb_opts = container_of(fi, struct f_lb_opts, func_inst);
+	kfree(lb_opts);
 }
+
+static struct usb_function_instance *loopback_alloc_instance(void)
+{
+	struct f_lb_opts *lb_opts;
+
+	lb_opts = kzalloc(sizeof(*lb_opts), GFP_KERNEL);
+	if (!lb_opts)
+		return ERR_PTR(-ENOMEM);
+	lb_opts->func_inst.free_func_inst = lb_free_instance;
+	return  &lb_opts->func_inst;
+}
+DECLARE_USB_FUNCTION(Loopback, loopback_alloc_instance, loopback_alloc);
+
+int __init lb_modinit(void)
+{
+	int ret;
+
+	ret = usb_function_register(&Loopbackusb_func);
+	if (ret)
+		return ret;
+	return ret;
+}
+void __exit lb_modexit(void)
+{
+	usb_function_unregister(&Loopbackusb_func);
+}
+
+MODULE_LICENSE("GPL");

drivers/usb/gadget/f_sourcesink.c

@@ -16,11 +16,12 @@
 #include <linux/kernel.h>
 #include <linux/device.h>
 #include <linux/module.h>
+#include <linux/usb/composite.h>
+#include <linux/err.h>
 
 #include "g_zero.h"
 #include "gadget_chips.h"
 
-
 /*
  * SOURCE/SINK FUNCTION ... a primary testing vehicle for USB peripheral
  * controller drivers.
@@ -62,24 +63,11 @@ static inline struct f_sourcesink *func_to_ss(struct usb_function *f)
 }
 
 static unsigned pattern;
-module_param(pattern, uint, S_IRUGO|S_IWUSR);
-MODULE_PARM_DESC(pattern, "0 = all zeroes, 1 = mod63, 2 = none");
-
-static unsigned isoc_interval = 4;
-module_param(isoc_interval, uint, S_IRUGO|S_IWUSR);
-MODULE_PARM_DESC(isoc_interval, "1 - 16");
-
-static unsigned isoc_maxpacket = 1024;
-module_param(isoc_maxpacket, uint, S_IRUGO|S_IWUSR);
-MODULE_PARM_DESC(isoc_maxpacket, "0 - 1023 (fs), 0 - 1024 (hs/ss)");
-
+static unsigned isoc_interval;
+static unsigned isoc_maxpacket;
 static unsigned isoc_mult;
-module_param(isoc_mult, uint, S_IRUGO|S_IWUSR);
-MODULE_PARM_DESC(isoc_mult, "0 - 2 (hs/ss only)");
-
 static unsigned isoc_maxburst;
-module_param(isoc_maxburst, uint, S_IRUGO|S_IWUSR);
-MODULE_PARM_DESC(isoc_maxburst, "0 - 15 (ss only)");
+static unsigned buflen;
 
 /*-------------------------------------------------------------------------*/
 
@@ -313,7 +301,57 @@ static struct usb_gadget_strings *sourcesink_strings[] = {
 
 /*-------------------------------------------------------------------------*/
 
-static int __init
+struct usb_request *alloc_ep_req(struct usb_ep *ep, int len)
+{
+	struct usb_request      *req;
+
+	req = usb_ep_alloc_request(ep, GFP_ATOMIC);
+	if (req) {
+		if (len)
+			req->length = len;
+		else
+			req->length = buflen;
+		req->buf = kmalloc(req->length, GFP_ATOMIC);
+		if (!req->buf) {
+			usb_ep_free_request(ep, req);
+			req = NULL;
+		}
+	}
+	return req;
+}
+
+void free_ep_req(struct usb_ep *ep, struct usb_request *req)
+{
+	kfree(req->buf);
+	usb_ep_free_request(ep, req);
+}
+
+static void disable_ep(struct usb_composite_dev *cdev, struct usb_ep *ep)
+{
+	int			value;
+
+	if (ep->driver_data) {
+		value = usb_ep_disable(ep);
+		if (value < 0)
+			DBG(cdev, "disable %s --> %d\n",
+					ep->name, value);
+		ep->driver_data = NULL;
+	}
+}
+
+void disable_endpoints(struct usb_composite_dev *cdev,
+		struct usb_ep *in, struct usb_ep *out,
+		struct usb_ep *iso_in, struct usb_ep *iso_out)
+{
+	disable_ep(cdev, in);
+	disable_ep(cdev, out);
+	if (iso_in)
+		disable_ep(cdev, iso_in);
+	if (iso_out)
+		disable_ep(cdev, iso_out);
+}
+
+static int
 sourcesink_bind(struct usb_configuration *c, struct usb_function *f)
 {
 	struct usb_composite_dev *cdev = c->cdev;
@@ -328,14 +366,6 @@ sourcesink_bind(struct usb_configuration *c, struct usb_function *f)
 	source_sink_intf_alt0.bInterfaceNumber = id;
 	source_sink_intf_alt1.bInterfaceNumber = id;
 
-	/* allocate string ID(s) */
-	id = usb_string_id(cdev);
-	if (id < 0)
-		return id;
-	strings_sourcesink[0].id = id;
-	source_sink_intf_alt0.iInterface = id;
-	source_sink_intf_alt1.iInterface = id;
-
 	/* allocate bulk endpoints */
 	ss->in_ep = usb_ep_autoconfig(cdev->gadget, &fs_source_desc);
 	if (!ss->in_ep) {
@@ -457,14 +487,11 @@ no_iso:
 	return 0;
 }
 
-static struct usb_function *global_ss_func;
-
 static void
-sourcesink_unbind(struct usb_configuration *c, struct usb_function *f)
+sourcesink_free_func(struct usb_function *f)
 {
 	usb_free_all_descriptors(f);
 	kfree(func_to_ss(f));
-	global_ss_func = NULL;
 }
 
 /* optionally require specific source/sink data patterns  */
@@ -767,6 +794,7 @@ static void sourcesink_disable(struct usb_function *f)
 }
 
 /*-------------------------------------------------------------------------*/
+
 static int sourcesink_setup(struct usb_function *f,
 		const struct usb_ctrlrequest *ctrl)
 {
@@ -839,41 +867,76 @@ unknown:
 	return value;
 }
 
-static int __init sourcesink_bind_config(struct usb_configuration *c)
+static struct usb_function *source_sink_alloc_func(
+		struct usb_function_instance *fi)
 {
-	struct f_sourcesink	*ss;
-	int			status;
+	struct f_sourcesink     *ss;
+	struct f_ss_opts	*ss_opts;
 
 	ss = kzalloc(sizeof(*ss), GFP_KERNEL);
 	if (!ss)
-		return -ENOMEM;
+		return NULL;
 
-	global_ss_func = &ss->function;
+	ss_opts =  container_of(fi, struct f_ss_opts, func_inst);
+	pattern = ss_opts->pattern;
+	isoc_interval = ss_opts->isoc_interval;
+	isoc_maxpacket = ss_opts->isoc_maxpacket;
+	isoc_mult = ss_opts->isoc_mult;
+	isoc_maxburst = ss_opts->isoc_maxburst;
+	buflen = ss_opts->bulk_buflen;
 
 	ss->function.name = "source/sink";
 	ss->function.bind = sourcesink_bind;
-	ss->function.unbind = sourcesink_unbind;
 	ss->function.set_alt = sourcesink_set_alt;
 	ss->function.get_alt = sourcesink_get_alt;
 	ss->function.disable = sourcesink_disable;
 	ss->function.setup = sourcesink_setup;
+	ss->function.strings = sourcesink_strings;
 
-	status = usb_add_function(c, &ss->function);
-	if (status)
-		kfree(ss);
-	return status;
+	ss->function.free_func = sourcesink_free_func;
+
+	return &ss->function;
 }
 
-static int ss_config_setup(struct usb_configuration *c,
-		const struct usb_ctrlrequest *ctrl)
+static void acm_free_instance(struct usb_function_instance *fi)
 {
-	if (!global_ss_func)
-		return -EOPNOTSUPP;
-	switch (ctrl->bRequest) {
-	case 0x5b:
-	case 0x5c:
-		return global_ss_func->setup(global_ss_func, ctrl);
-	default:
-		return -EOPNOTSUPP;
-	}
+	struct f_ss_opts *ss_opts;
+
+	ss_opts = container_of(fi, struct f_ss_opts, func_inst);
+	kfree(ss_opts);
 }
+
+static struct usb_function_instance *source_sink_alloc_inst(void)
+{
+	struct f_ss_opts *ss_opts;
+
+	ss_opts = kzalloc(sizeof(*ss_opts), GFP_KERNEL);
+	if (!ss_opts)
+		return ERR_PTR(-ENOMEM);
+	ss_opts->func_inst.free_func_inst = acm_free_instance;
+	return &ss_opts->func_inst;
+}
+DECLARE_USB_FUNCTION(SourceSink, source_sink_alloc_inst,
+		source_sink_alloc_func);
+
+static int __init sslb_modinit(void)
+{
+	int ret;
+
+	ret = usb_function_register(&SourceSinkusb_func);
+	if (ret)
+		return ret;
+	ret = lb_modinit();
+	if (ret)
+		usb_function_unregister(&SourceSinkusb_func);
+	return ret;
+}
+static void __exit sslb_modexit(void)
+{
+	usb_function_unregister(&SourceSinkusb_func);
+	lb_modexit();
+}
+module_init(sslb_modinit);
+module_exit(sslb_modexit);
+
+MODULE_LICENSE("GPL");

drivers/usb/gadget/g_zero.h

@@ -6,11 +6,34 @@
 #ifndef __G_ZERO_H
 #define __G_ZERO_H
 
-#include <linux/usb/composite.h>
+struct usb_zero_options {
+	unsigned pattern;
+	unsigned isoc_interval;
+	unsigned isoc_maxpacket;
+	unsigned isoc_mult;
+	unsigned isoc_maxburst;
+	unsigned bulk_buflen;
+	unsigned qlen;
+};
 
-/* global state */
-extern unsigned buflen;
-extern const struct usb_descriptor_header *otg_desc[];
+struct f_ss_opts {
+	struct usb_function_instance func_inst;
+	unsigned pattern;
+	unsigned isoc_interval;
+	unsigned isoc_maxpacket;
+	unsigned isoc_mult;
+	unsigned isoc_maxburst;
+	unsigned bulk_buflen;
+};
+
+struct f_lb_opts {
+	struct usb_function_instance func_inst;
+	unsigned bulk_buflen;
+	unsigned qlen;
+};
+
+void lb_modexit(void);
+int lb_modinit(void);
 
 /* common utilities */
 struct usb_request *alloc_ep_req(struct usb_ep *ep, int len);

drivers/usb/gadget/zero.c

@@ -10,7 +10,6 @@
  * (at your option) any later version.
  */
 
-
 /*
  * Gadget Zero only needs two bulk endpoints, and is an example of how you
  * can write a hardware-agnostic gadget driver running inside a USB device.
@@ -43,23 +42,11 @@
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/device.h>
+#include <linux/module.h>
+#include <linux/err.h>
+#include <linux/usb/composite.h>
 
 #include "g_zero.h"
-#include "gadget_chips.h"
-
-
-/*-------------------------------------------------------------------------*/
-
-/*
- * Kbuild is not very cooperative with respect to linking separately
- * compiled library objects into one module.  So for now we won't use
- * separate compilation ... ensuring init/exit sections work to shrink
- * the runtime footprint, and giving us at least some parts of what
- * a "gcc --combine ... part1.c part2.c part3.c ... " build would.
- */
-#include "f_sourcesink.c"
-#include "f_loopback.c"
-
 /*-------------------------------------------------------------------------*/
 USB_GADGET_COMPOSITE_OPTIONS();
 
@@ -67,9 +54,6 @@ USB_GADGET_COMPOSITE_OPTIONS();
 
 static const char longname[] = "Gadget Zero";
 
-unsigned buflen = 4096;		/* only used for bulk endpoints */
-module_param(buflen, uint, 0);
-
 /*
  * Normally the "loopback" configuration is second (index 1) so
  * it's not the default.  Here's where to change that order, to
@@ -79,6 +63,13 @@ module_param(buflen, uint, 0);
 static bool loopdefault = 0;
 module_param(loopdefault, bool, S_IRUGO|S_IWUSR);
 
+struct usb_zero_options gzero_options = {
+	.isoc_interval = 4,
+	.isoc_maxpacket = 1024,
+	.bulk_buflen = 4096,
+	.qlen = 32,
+};
+
 /*-------------------------------------------------------------------------*/
 
 /* Thanks to NetChip Technologies for donating this product ID.
@@ -129,10 +120,12 @@ static struct usb_otg_descriptor otg_descriptor = {
 	.bmAttributes =		USB_OTG_SRP | USB_OTG_HNP,
 };
 
-const struct usb_descriptor_header *otg_desc[] = {
+static const struct usb_descriptor_header *otg_desc[] = {
 	(struct usb_descriptor_header *) &otg_descriptor,
 	NULL,
 };
+#else
+#define otg_desc	NULL
 #endif
 
 /* string IDs are assigned dynamically */
@@ -163,58 +156,6 @@ static struct usb_gadget_strings *dev_strings[] = {
 
 /*-------------------------------------------------------------------------*/
 
-struct usb_request *alloc_ep_req(struct usb_ep *ep, int len)
-{
-	struct usb_request	*req;
-
-	req = usb_ep_alloc_request(ep, GFP_ATOMIC);
-	if (req) {
-		if (len)
-			req->length = len;
-		else
-			req->length = buflen;
-		req->buf = kmalloc(req->length, GFP_ATOMIC);
-		if (!req->buf) {
-			usb_ep_free_request(ep, req);
-			req = NULL;
-		}
-	}
-	return req;
-}
-
-void free_ep_req(struct usb_ep *ep, struct usb_request *req)
-{
-	kfree(req->buf);
-	usb_ep_free_request(ep, req);
-}
-
-static void disable_ep(struct usb_composite_dev *cdev, struct usb_ep *ep)
-{
-	int			value;
-
-	if (ep->driver_data) {
-		value = usb_ep_disable(ep);
-		if (value < 0)
-			DBG(cdev, "disable %s --> %d\n",
-					ep->name, value);
-		ep->driver_data = NULL;
-	}
-}
-
-void disable_endpoints(struct usb_composite_dev *cdev,
-		struct usb_ep *in, struct usb_ep *out,
-		struct usb_ep *iso_in, struct usb_ep *iso_out)
-{
-	disable_ep(cdev, in);
-	disable_ep(cdev, out);
-	if (iso_in)
-		disable_ep(cdev, iso_in);
-	if (iso_out)
-		disable_ep(cdev, iso_out);
-}
-
-/*-------------------------------------------------------------------------*/
-
 static struct timer_list	autoresume_timer;
 
 static void zero_autoresume(unsigned long _c)
@@ -258,23 +199,63 @@ static void zero_resume(struct usb_composite_dev *cdev)
 
 static struct usb_configuration loopback_driver = {
 	.label          = "loopback",
-	.strings        = loopback_strings,
 	.bConfigurationValue = 2,
 	.bmAttributes   = USB_CONFIG_ATT_SELFPOWER,
 	/* .iConfiguration = DYNAMIC */
 };
 
+static struct usb_function *func_ss;
+static struct usb_function_instance *func_inst_ss;
+
+static int ss_config_setup(struct usb_configuration *c,
+		const struct usb_ctrlrequest *ctrl)
+{
+	switch (ctrl->bRequest) {
+	case 0x5b:
+	case 0x5c:
+		return func_ss->setup(func_ss, ctrl);
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
 static struct usb_configuration sourcesink_driver = {
 	.label                  = "source/sink",
-	.strings                = sourcesink_strings,
 	.setup                  = ss_config_setup,
 	.bConfigurationValue    = 3,
 	.bmAttributes           = USB_CONFIG_ATT_SELFPOWER,
 	/* .iConfiguration      = DYNAMIC */
 };
 
+module_param_named(buflen, gzero_options.bulk_buflen, uint, 0);
+module_param_named(pattern, gzero_options.pattern, uint, S_IRUGO|S_IWUSR);
+MODULE_PARM_DESC(pattern, "0 = all zeroes, 1 = mod63, 2 = none");
+
+module_param_named(isoc_interval, gzero_options.isoc_interval, uint,
+		S_IRUGO|S_IWUSR);
+MODULE_PARM_DESC(isoc_interval, "1 - 16");
+
+module_param_named(isoc_maxpacket, gzero_options.isoc_maxpacket, uint,
+		S_IRUGO|S_IWUSR);
+MODULE_PARM_DESC(isoc_maxpacket, "0 - 1023 (fs), 0 - 1024 (hs/ss)");
+
+module_param_named(isoc_mult, gzero_options.isoc_mult, uint, S_IRUGO|S_IWUSR);
+MODULE_PARM_DESC(isoc_mult, "0 - 2 (hs/ss only)");
+
+module_param_named(isoc_maxburst, gzero_options.isoc_maxburst, uint,
+		S_IRUGO|S_IWUSR);
+MODULE_PARM_DESC(isoc_maxburst, "0 - 15 (ss only)");
+
+static struct usb_function *func_lb;
+static struct usb_function_instance *func_inst_lb;
+
+module_param_named(qlen, gzero_options.qlen, uint, S_IRUGO|S_IWUSR);
+MODULE_PARM_DESC(qlen, "depth of loopback queue");
+
 static int __init zero_bind(struct usb_composite_dev *cdev)
 {
+	struct f_ss_opts	*ss_opts;
+	struct f_lb_opts	*lb_opts;
 	int			status;
 
 	/* Allocate string descriptor numbers ... note that string
@@ -290,6 +271,36 @@ static int __init zero_bind(struct usb_composite_dev *cdev)
 
 	setup_timer(&autoresume_timer, zero_autoresume, (unsigned long) cdev);
 
+	func_inst_ss = usb_get_function_instance("SourceSink");
+	if (IS_ERR(func_inst_ss))
+		return PTR_ERR(func_inst_ss);
+
+	ss_opts =  container_of(func_inst_ss, struct f_ss_opts, func_inst);
+	ss_opts->pattern = gzero_options.pattern;
+	ss_opts->isoc_interval = gzero_options.isoc_interval;
+	ss_opts->isoc_maxpacket = gzero_options.isoc_maxpacket;
+	ss_opts->isoc_mult = gzero_options.isoc_mult;
+	ss_opts->isoc_maxburst = gzero_options.isoc_maxpacket;
+	ss_opts->bulk_buflen = gzero_options.bulk_buflen;
+
+	func_ss = usb_get_function(func_inst_ss);
+	if (IS_ERR(func_ss))
+		goto err_put_func_inst_ss;
+
+	func_inst_lb = usb_get_function_instance("Loopback");
+	if (IS_ERR(func_inst_lb))
+		goto err_put_func_ss;
+
+	lb_opts = container_of(func_inst_lb, struct f_lb_opts, func_inst);
+	lb_opts->bulk_buflen = gzero_options.bulk_buflen;
+	lb_opts->qlen = gzero_options.qlen;
+
+	func_lb = usb_get_function(func_inst_lb);
+	if (IS_ERR(func_lb)) {
+		status = PTR_ERR(func_lb);
+		goto err_put_func_inst_lb;
+	}
+
 	sourcesink_driver.iConfiguration = strings_dev[USB_GZERO_SS_DESC].id;
 	loopback_driver.iConfiguration = strings_dev[USB_GZERO_LB_DESC].id;
 
@@ -315,25 +326,50 @@ static int __init zero_bind(struct usb_composite_dev *cdev)
 	 * SH3 only allows one config...
 	 */
 	if (loopdefault) {
-		usb_add_config(cdev, &loopback_driver, loopback_bind_config);
-		usb_add_config(cdev, &sourcesink_driver,
-				sourcesink_bind_config);
+		usb_add_config_only(cdev, &loopback_driver);
+		usb_add_config_only(cdev, &sourcesink_driver);
 	} else {
-		usb_add_config(cdev, &sourcesink_driver,
-				sourcesink_bind_config);
-		usb_add_config(cdev, &loopback_driver, loopback_bind_config);
+		usb_add_config_only(cdev, &sourcesink_driver);
+		usb_add_config_only(cdev, &loopback_driver);
 	}
+	status = usb_add_function(&sourcesink_driver, func_ss);
+	if (status)
+		goto err_conf_flb;
 
+	usb_ep_autoconfig_reset(cdev->gadget);
+	status = usb_add_function(&loopback_driver, func_lb);
+	if (status)
+		goto err_conf_flb;
+
+	usb_ep_autoconfig_reset(cdev->gadget);
 	usb_composite_overwrite_options(cdev, &coverwrite);
 
 	INFO(cdev, "%s, version: " DRIVER_VERSION "\n", longname);
 
 	return 0;
+
+err_conf_flb:
+	usb_put_function(func_lb);
+	func_lb = NULL;
+err_put_func_inst_lb:
+	usb_put_function_instance(func_inst_lb);
+	func_inst_lb = NULL;
+err_put_func_ss:
+	usb_put_function(func_ss);
+	func_ss = NULL;
+err_put_func_inst_ss:
+	usb_put_function_instance(func_inst_ss);
+	func_inst_ss = NULL;
+	return status;
 }
 
 static int zero_unbind(struct usb_composite_dev *cdev)
 {
 	del_timer_sync(&autoresume_timer);
+	if (!IS_ERR_OR_NULL(func_ss))
+		usb_put_function(func_ss);
+	if (!IS_ERR_OR_NULL(func_lb))
+		usb_put_function(func_lb);
 	return 0;
 }