platform/chrome: cros_ec_proto: Allow to build as module

Allow to build ChromeOS EC communication protocol helpers as
kernel module which is particularly useful for Android GKI (Generic
Kernel Image) configuration. With this change the ChromeOS Platform
(CONFIG_CHROME_PLATFORMS=y) can be enabled directly from the vendor
kconfig fragment whithout additional configuration in gki_defconfig.

Signed-off-by: Slawomir Rosek <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Tzung-Bi Shih <[email protected]>

Author: Slawomir Rosek

drivers/platform/chrome/Kconfig

@@ -155,7 +155,7 @@ config CROS_EC_LPC
 	  module will be called cros_ec_lpcs.
 
 config CROS_EC_PROTO
-	bool
+	tristate
 	help
 	  ChromeOS EC communication protocol helpers.
 

drivers/platform/chrome/Makefile

@@ -25,7 +25,8 @@ endif
 obj-$(CONFIG_CROS_EC_TYPEC)		+= cros-ec-typec.o
 
 obj-$(CONFIG_CROS_EC_LPC)		+= cros_ec_lpcs.o
-obj-$(CONFIG_CROS_EC_PROTO)		+= cros_ec_proto.o cros_ec_trace.o
+cros-ec-proto-objs			:= cros_ec_proto.o cros_ec_trace.o
+obj-$(CONFIG_CROS_EC_PROTO)		+= cros-ec-proto.o
 obj-$(CONFIG_CROS_KBD_LED_BACKLIGHT)	+= cros_kbd_led_backlight.o
 obj-$(CONFIG_CROS_EC_CHARDEV)		+= cros_ec_chardev.o
 obj-$(CONFIG_CROS_EC_LIGHTBAR)		+= cros_ec_lightbar.o

drivers/platform/chrome/cros_ec_proto.c

@@ -1152,3 +1152,6 @@ int cros_ec_get_cmd_versions(struct cros_ec_device *ec_dev, u16 cmd)
 		return resp.version_mask;
 }
 EXPORT_SYMBOL_GPL(cros_ec_get_cmd_versions);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("ChromeOS EC communication protocol helpers");