diff --git a/drivers/staging/greybus/battery-gb.c b/drivers/staging/greybus/battery-gb.c
index df1d7ee08199..f6b0dd681430 100644
--- a/drivers/staging/greybus/battery-gb.c
+++ b/drivers/staging/greybus/battery-gb.c
@@ -367,7 +367,7 @@ static struct gb_protocol battery_protocol = {
 	.request_recv		= NULL,	/* no incoming requests */
 };
 
-bool gb_battery_protocol_init(void)
+int gb_battery_protocol_init(void)
 {
 	return gb_protocol_register(&battery_protocol);
 }
diff --git a/drivers/staging/greybus/gpio-gb.c b/drivers/staging/greybus/gpio-gb.c
index 152ba50d1693..cf60a4a96b29 100644
--- a/drivers/staging/greybus/gpio-gb.c
+++ b/drivers/staging/greybus/gpio-gb.c
@@ -532,7 +532,7 @@ static struct gb_protocol gpio_protocol = {
 	.request_recv		= NULL,	/* no incoming requests */
 };
 
-bool gb_gpio_protocol_init(void)
+int gb_gpio_protocol_init(void)
 {
 	return gb_protocol_register(&gpio_protocol);
 }
diff --git a/drivers/staging/greybus/i2c-gb.c b/drivers/staging/greybus/i2c-gb.c
index 491fac4feaf3..b78de6b4be10 100644
--- a/drivers/staging/greybus/i2c-gb.c
+++ b/drivers/staging/greybus/i2c-gb.c
@@ -438,7 +438,7 @@ static struct gb_protocol i2c_protocol = {
 	.request_recv		= NULL,	/* no incoming requests */
 };
 
-bool gb_i2c_protocol_init(void)
+int gb_i2c_protocol_init(void)
 {
 	return gb_protocol_register(&i2c_protocol);
 }
diff --git a/drivers/staging/greybus/protocol.c b/drivers/staging/greybus/protocol.c
index 4ca3ae533354..227c531fa903 100644
--- a/drivers/staging/greybus/protocol.c
+++ b/drivers/staging/greybus/protocol.c
@@ -39,8 +39,7 @@ static struct gb_protocol *_gb_protocol_find(u8 id, u8 major, u8 minor)
 	return NULL;
 }
 
-/* Returns true if protocol was successfully registered, false otherwise */
-bool gb_protocol_register(struct gb_protocol *protocol)
+int gb_protocol_register(struct gb_protocol *protocol)
 {
 	struct gb_protocol *existing;
 	u8 id = protocol->id;
@@ -75,7 +74,7 @@ bool gb_protocol_register(struct gb_protocol *protocol)
 		/* A matching protocol has already been registered */
 		spin_unlock_irq(&gb_protocols_lock);
 
-		return false;
+		return -EEXIST;
 	}
 
 	/*
@@ -85,7 +84,7 @@ bool gb_protocol_register(struct gb_protocol *protocol)
 	list_add_tail(&protocol->links, &existing->links);
 	spin_unlock_irq(&gb_protocols_lock);
 
-	return true;
+	return 0;
 }
 
 /*
@@ -99,10 +98,13 @@ bool gb_protocol_register(struct gb_protocol *protocol)
  *
  * Returns true if successful, false otherwise.
  */
-bool gb_protocol_deregister(struct gb_protocol *protocol)
+int gb_protocol_deregister(struct gb_protocol *protocol)
 {
 	u8 protocol_count = 0;
 
+	if (!protocol)
+		return 0;
+
 	spin_lock_irq(&gb_protocols_lock);
 	protocol = _gb_protocol_find(protocol->id, protocol->major,
 						protocol->minor);
@@ -166,35 +168,35 @@ bool gb_protocol_init(void)
 {
 	bool ret = true;
 
-	if (!gb_battery_protocol_init()) {
+	if (gb_battery_protocol_init()) {
 		pr_err("error initializing battery protocol\n");
 		ret = false;
 	}
-	if (!gb_gpio_protocol_init()) {
+	if (gb_gpio_protocol_init()) {
 		pr_err("error initializing gpio protocol\n");
 		ret = false;
 	}
-	if (!gb_i2c_protocol_init()) {
+	if (gb_i2c_protocol_init()) {
 		pr_err("error initializing i2c protocol\n");
 		ret = false;
 	}
-	if (!gb_pwm_protocol_init()) {
+	if (gb_pwm_protocol_init()) {
 		pr_err("error initializing pwm protocol\n");
 		ret = false;
 	}
-	if (!gb_uart_protocol_init()) {
+	if (gb_uart_protocol_init()) {
 		pr_err("error initializing uart protocol\n");
 		ret = false;
 	}
-	if (!gb_sdio_protocol_init()) {
+	if (gb_sdio_protocol_init()) {
 		pr_err("error initializing sdio protocol\n");
 		ret = false;
 	}
-	if (!gb_vibrator_protocol_init()) {
+	if (gb_vibrator_protocol_init()) {
 		pr_err("error initializing vibrator protocol\n");
 		ret = false;
 	}
-	if (!gb_usb_protocol_init()) {
+	if (gb_usb_protocol_init()) {
 		pr_err("error initializing usb protocol\n");
 		ret = false;
 	}
diff --git a/drivers/staging/greybus/protocol.h b/drivers/staging/greybus/protocol.h
index 7d33b20b1808..49214d6a9af0 100644
--- a/drivers/staging/greybus/protocol.h
+++ b/drivers/staging/greybus/protocol.h
@@ -36,8 +36,8 @@ struct gb_protocol {
 	gb_request_recv_t	request_recv;
 };
 
-bool gb_protocol_register(struct gb_protocol *protocol);
-bool gb_protocol_deregister(struct gb_protocol *protocol);
+int gb_protocol_register(struct gb_protocol *protocol);
+int gb_protocol_deregister(struct gb_protocol *protocol);
 
 struct gb_protocol *gb_protocol_get(u8 id, u8 major, u8 minor);
 void gb_protocol_put(struct gb_protocol *protocol);
@@ -47,28 +47,28 @@ void gb_protocol_put(struct gb_protocol *protocol);
  * Declared here for now.  They could be added via modules, or maybe
  * just use initcalls (which level?).
  */
-extern bool gb_battery_protocol_init(void);
+extern int gb_battery_protocol_init(void);
 extern void gb_battery_protocol_exit(void);
 
-extern bool gb_gpio_protocol_init(void);
+extern int gb_gpio_protocol_init(void);
 extern void gb_gpio_protocol_exit(void);
 
-extern bool gb_i2c_protocol_init(void);
+extern int gb_i2c_protocol_init(void);
 extern void gb_i2c_protocol_exit(void);
 
-extern bool gb_pwm_protocol_init(void);
+extern int gb_pwm_protocol_init(void);
 extern void gb_pwm_protocol_exit(void);
 
-extern bool gb_uart_protocol_init(void);
+extern int gb_uart_protocol_init(void);
 extern void gb_uart_protocol_exit(void);
 
-extern bool gb_sdio_protocol_init(void);
+extern int gb_sdio_protocol_init(void);
 extern void gb_sdio_protocol_exit(void);
 
-extern bool gb_vibrator_protocol_init(void);
+extern int gb_vibrator_protocol_init(void);
 extern void gb_vibrator_protocol_exit(void);
 
-extern bool gb_usb_protocol_init(void);
+extern int gb_usb_protocol_init(void);
 extern void gb_usb_protocol_exit(void);
 
 bool gb_protocol_init(void);
diff --git a/drivers/staging/greybus/pwm-gb.c b/drivers/staging/greybus/pwm-gb.c
index c505f1d2d676..5f02e7802949 100644
--- a/drivers/staging/greybus/pwm-gb.c
+++ b/drivers/staging/greybus/pwm-gb.c
@@ -319,7 +319,7 @@ static struct gb_protocol pwm_protocol = {
 	.request_recv		= NULL, /* no incoming requests */
 };
 
-bool gb_pwm_protocol_init(void)
+int gb_pwm_protocol_init(void)
 {
 	return gb_protocol_register(&pwm_protocol);
 }
diff --git a/drivers/staging/greybus/sdio-gb.c b/drivers/staging/greybus/sdio-gb.c
index 8de7dc467b31..13293a6f358e 100644
--- a/drivers/staging/greybus/sdio-gb.c
+++ b/drivers/staging/greybus/sdio-gb.c
@@ -87,7 +87,7 @@ static struct gb_protocol sdio_protocol = {
 	.request_recv		= NULL,	/* no incoming requests */
 };
 
-bool gb_sdio_protocol_init(void)
+int gb_sdio_protocol_init(void)
 {
 	return gb_protocol_register(&sdio_protocol);
 }
diff --git a/drivers/staging/greybus/uart-gb.c b/drivers/staging/greybus/uart-gb.c
index faba00ef1c22..825de7462f7b 100644
--- a/drivers/staging/greybus/uart-gb.c
+++ b/drivers/staging/greybus/uart-gb.c
@@ -775,7 +775,7 @@ static struct gb_protocol uart_protocol = {
 	.request_recv		= NULL,	/* FIXME we have 2 types of requests!!! */
 };
 
-bool gb_uart_protocol_init(void)
+int gb_uart_protocol_init(void)
 {
 	return gb_protocol_register(&uart_protocol);
 }
diff --git a/drivers/staging/greybus/usb-gb.c b/drivers/staging/greybus/usb-gb.c
index 2b5f69e59a46..b3ba50b502ec 100644
--- a/drivers/staging/greybus/usb-gb.c
+++ b/drivers/staging/greybus/usb-gb.c
@@ -384,7 +384,7 @@ static struct gb_protocol usb_protocol = {
 	.request_recv		= NULL,	/* FIXME we have requests!!! */
 };
 
-bool gb_usb_protocol_init(void)
+int gb_usb_protocol_init(void)
 {
 	return gb_protocol_register(&usb_protocol);
 }
diff --git a/drivers/staging/greybus/vibrator-gb.c b/drivers/staging/greybus/vibrator-gb.c
index fb48112692cf..3ef7d06160bb 100644
--- a/drivers/staging/greybus/vibrator-gb.c
+++ b/drivers/staging/greybus/vibrator-gb.c
@@ -205,7 +205,7 @@ static struct gb_protocol vibrator_protocol = {
 	.request_recv		= NULL,	/* no incoming requests */
 };
 
-bool gb_vibrator_protocol_init(void)
+int gb_vibrator_protocol_init(void)
 {
 	int retval;