usb: dwc3: remove dwc3 dependency on host AND gadget.

DWC3 controller curretly depends on USB && USB_GADGET.
Some hardware may like to use only host feature on dwc3,
or only gadget feature.

So, removing this dependency of USB_DWC3 on USB and USB_GADGET.
Adding the mode of operaiton of DWC3 also here
HOST/GADGET/DUAL_ROLE based on which features are enabled.

[ balbi@ti.com :
	. make sure we have default modes for all possible Kernel
		configurations.
	. Remove the config -> menuconfig change as it's unnecessary
	. switch over to IS_ENABLED() ]

CC: Doug Anderson <dianders@chromium.org>
Signed-off-by: NVivek Gautam <gautam.vivek@samsung.com>
Signed-off-by: NFelipe Balbi <balbi@ti.com>

drivers/usb/dwc3/Kconfig

 config USB_DWC3
 	tristate "DesignWare USB3 DRD Core Support"
-	depends on (USB && USB_GADGET)
+	depends on (USB || USB_GADGET)
 	select USB_OTG_UTILS
 	select USB_XHCI_PLATFORM if USB_SUPPORT && USB_XHCI_HCD
 	help
@@ -12,6 +12,35 @@ config USB_DWC3
 
 if USB_DWC3
 
+choice
+	bool "DWC3 Mode Selection"
+	default USB_DWC3_DUAL_ROLE if (USB && USB_GADGET)
+	default USB_DWC3_HOST if (USB && !USB_GADGET)
+	default USB_DWC3_GADGET if (!USB && USB_GADGET)
+
+config USB_DWC3_HOST
+	bool "Host only mode"
+	depends on USB
+	help
+	  Select this when you want to use DWC3 in host mode only,
+	  thereby the gadget feature will be regressed.
+
+config USB_DWC3_GADGET
+	bool "Gadget only mode"
+	depends on USB_GADGET
+	help
+	  Select this when you want to use DWC3 in gadget mode only,
+	  thereby the host feature will be regressed.
+
+config USB_DWC3_DUAL_ROLE
+	bool "Dual Role mode"
+	depends on (USB && USB_GADGET)
+	help
+	  This is the default mode of working of DWC3 controller where
+	  both host and gadget features are enabled.
+
+endchoice
+
 config USB_DWC3_DEBUG
 	bool "Enable Debugging Messages"
 	help

drivers/usb/dwc3/Makefile

@@ -4,8 +4,14 @@ ccflags-$(CONFIG_USB_DWC3_VERBOSE)	+= -DVERBOSE_DEBUG
 obj-$(CONFIG_USB_DWC3)			+= dwc3.o
 
 dwc3-y					:= core.o
-dwc3-y					+= host.o
-dwc3-y					+= gadget.o ep0.o
+
+ifneq ($(filter y,$(CONFIG_USB_DWC3_HOST) $(CONFIG_USB_DWC3_DUAL_ROLE)),)
+	dwc3-y				+= host.o
+endif
+
+ifneq ($(filter y,$(CONFIG_USB_DWC3_GADGET) $(CONFIG_USB_DWC3_DUAL_ROLE)),)
+	dwc3-y				+= gadget.o ep0.o
+endif
 
 ifneq ($(CONFIG_DEBUG_FS),)
 	dwc3-y				+= debugfs.o

drivers/usb/dwc3/core.h

@@ -864,10 +864,24 @@ union dwc3_event {
 void dwc3_set_mode(struct dwc3 *dwc, u32 mode);
 int dwc3_gadget_resize_tx_fifos(struct dwc3 *dwc);
 
+#if IS_ENABLED(CONFIG_USB_DWC3_HOST) || IS_ENABLED(CONFIG_USB_DWC3_DUAL_ROLE)
 int dwc3_host_init(struct dwc3 *dwc);
 void dwc3_host_exit(struct dwc3 *dwc);
-
+#else
+static inline int dwc3_host_init(struct dwc3 *dwc)
+{ return 0; }
+static inline void dwc3_host_exit(struct dwc3 *dwc)
+{ }
+#endif
+
+#if IS_ENABLED(CONFIG_USB_DWC3_GADGET) || IS_ENABLED(CONFIG_USB_DWC3_DUAL_ROLE)
 int dwc3_gadget_init(struct dwc3 *dwc);
 void dwc3_gadget_exit(struct dwc3 *dwc);
+#else
+static inline int dwc3_gadget_init(struct dwc3 *dwc)
+{ return 0; }
+static inline void dwc3_gadget_exit(struct dwc3 *dwc)
+{ }
+#endif
 
 #endif /* __DRIVERS_USB_DWC3_CORE_H */

drivers/usb/dwc3/debugfs.c

@@ -661,6 +661,7 @@ int dwc3_debugfs_init(struct dwc3 *dwc)
 		goto err1;
 	}
 
+#if IS_ENABLED(CONFIG_USB_DWC3_GADGET)
 	file = debugfs_create_file("mode", S_IRUGO | S_IWUSR, root,
 			dwc, &dwc3_mode_fops);
 	if (!file) {
@@ -681,6 +682,7 @@ int dwc3_debugfs_init(struct dwc3 *dwc)
 		ret = -ENOMEM;
 		goto err1;
 	}
+#endif
 
 	return 0;