staging: vchiq: Make creation of vchiq cdev optional

Before this commit, vchiq cdev (/dev/vchiq) was always created during
platform initialization. Introduce a new Kconfig option
CONFIG_VCHIQ_CDEV which determines if the cdev will be created or not.

Reviewed-by: Stefan Wahren <[e-mail]>
Signed-off-by: Ojaswin Mujoo <[e-mail]>
Link: https://lore.kernel.org/r/8[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/staging/vc04_services/Kconfig

···
 		Defaults to Y when the Broadcom Videocore services
 		are included in the build, N otherwise.
 
+if BCM2835_VCHIQ
+
+config VCHIQ_CDEV
+	bool "VCHIQ Character Driver"
+	help
+		Enable the creation of VCHIQ character driver to help
+		communicate with the Videocore platform.
+
+endif
+
 source "drivers/staging/vc04_services/bcm2835-audio/Kconfig"
 
 source "drivers/staging/vc04_services/bcm2835-camera/Kconfig"

drivers/staging/vc04_services/Makefile

···
    interface/vchiq_arm/vchiq_2835_arm.o \
    interface/vchiq_arm/vchiq_debugfs.o \
    interface/vchiq_arm/vchiq_connected.o \
-   interface/vchiq_arm/vchiq_dev.o \
+
+ifdef CONFIG_VCHIQ_CDEV
+vchiq-objs += interface/vchiq_arm/vchiq_dev.o
+endif
 
 obj-$(CONFIG_SND_BCM2835)		+= bcm2835-audio/
 obj-$(CONFIG_VIDEO_BCM2835)		+= bcm2835-camera/

drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.h

···
 extern void
 vchiq_instance_set_trace(struct vchiq_instance *instance, int trace);
 
+#if IS_ENABLED(CONFIG_VCHIQ_CDEV)
+
 extern void
 vchiq_deregister_chrdev(void);
 
 extern int
 vchiq_register_chrdev(struct device *parent);
+
+#else
+
+static inline void vchiq_deregister_chrdev(void) { }
+static inline int vchiq_register_chrdev(struct device *parent) { return 0; }
+
+#endif /* IS_ENABLED(CONFIG_VCHIQ_CDEV) */
 
 extern enum vchiq_status
 service_callback(enum vchiq_reason reason, struct vchiq_header *header,