Conditionally compile USB-PD support

Boards may not have USB-PD. Remove the need for a "none" option by only
adding USB-PD sources when enabled.

The resulting binary for boards with USB-PD enabled (addw3, bonw15,
serw13) are identical. The binary for boards without USB-PD now have the
empty calls optimized out.

Signed-off-by: Tim Crawford <tcrawford@system76.com>

src/board/system76/bonw15/board.mk

@@ -29,8 +29,6 @@ CFLAGS+=-DI2C_SMBUS=I2C_4
 # Set touchpad PS2 bus
 CFLAGS+=-DPS2_TOUCHPAD=PS2_3
 
-# Set USB-PD I2C bus
-CFLAGS+=-DI2C_USBPD=I2C_1
 
 # Set smart charger parameters
 # XXX: PRS1 and PRS2 are in parallel for adapter Rsense?
@@ -43,7 +41,9 @@ CFLAGS+=\
 	-DCHARGER_INPUT_CURRENT=16920
 
 # Set USB-PD parameters
-USBPD=tps65987
+CONFIG_HAVE_USBPD = y
+CONFIG_USBPD_TPS65987 = y
+CFLAGS += -DI2C_USBPD=I2C_1
 
 # Set CPU power limits in watts
 CFLAGS+=\

src/board/system76/common/common.mk

@@ -76,8 +76,10 @@ CHARGER?=bq24780s
 board-common-y += charger/$(CHARGER).c
 
 # Add USB-PD
-USBPD?=none
+ifeq ($(CONFIG_HAVE_USBPD),y)
-board-common-y += usbpd/$(USBPD).c
+CFLAGS += -DCONFIG_HAVE_USBPD=1
+board-common-$(CONFIG_USBPD_TPS65987) += usbpd/tps65987.c
+endif
 
 # Add keyboard
 ifndef KEYBOARD

src/board/system76/common/include/board/usbpd.h

@@ -3,9 +3,20 @@
 #ifndef _BOARD_USBPD_H
 #define _BOARD_USBPD_H
 
+#if CONFIG_HAVE_USBPD
+
 void usbpd_init(void);
 void usbpd_event(void);
 void usbpd_disable_charging(void);
 void usbpd_enable_charging(void);
 
+#else
+
+static inline void usbpd_init(void) {}
+static inline void usbpd_event(void) {}
+static inline void usbpd_disable_charging(void) {}
+static inline void usbpd_enable_charging(void) {}
+
+#endif
+
 #endif // _BOARD_USBPD_H

src/board/system76/common/usbpd/none.c

@@ -1,11 +0,0 @@
-// SPDX-License-Identifier: GPL-3.0-only
-
-#include <board/usbpd.h>
-
-void usbpd_init(void) {}
-
-void usbpd_event(void) {}
-
-void usbpd_disable_charging(void) {}
-
-void usbpd_enable_charging(void) {}

src/board/system76/oryp11/board.mk

@@ -31,8 +31,6 @@ CFLAGS+=-DI2C_SMBUS=I2C_4
 # Set touchpad PS2 bus
 CFLAGS+=-DPS2_TOUCHPAD=PS2_3
 
-# Set USB-PD I2C bus
-CFLAGS+=-DI2C_USBPD=I2C_1
 
 # Set smart charger parameters
 # TODO: actually bq24800
@@ -45,7 +43,9 @@ CFLAGS+=\
 	-DCHARGER_INPUT_CURRENT=11500
 
 # Set USB-PD parameters
-USBPD=tps65987
+CONFIG_HAVE_USBPD = y
+CONFIG_USBPD_TPS65987 = y
+CFLAGS += -DI2C_USBPD=I2C_1
 
 # Set CPU power limits in watts
 CFLAGS+=\

src/board/system76/serw13/board.mk

@@ -29,8 +29,6 @@ CFLAGS+=-DI2C_SMBUS=I2C_4
 # Set touchpad PS2 bus
 CFLAGS+=-DPS2_TOUCHPAD=PS2_3
 
-# Set USB-PD I2C bus
-CFLAGS+=-DI2C_USBPD=I2C_1
 
 # Set smart charger parameters
 # TODO: actually bq24800
@@ -42,7 +40,9 @@ CFLAGS+=\
 	-DCHARGER_INPUT_CURRENT=14000
 
 # Set USB-PD parameters
-USBPD=tps65987
+CONFIG_HAVE_USBPD = y
+CONFIG_USBPD_TPS65987 = y
+CFLAGS += -DI2C_USBPD=I2C_1
 
 # Set CPU power limits in watts
 CFLAGS+=\