beltino: Fix recovery button

This patch fixes the use of the recovery button on
Beltino devices. In order to have the recovery button
available as early as possible, the value is stored
in a SATA controller scratch register (similarly as
it has been done on other ChromeOS devices)

BUG=none
BRANCH=none
TEST=Use recovery button

Change-Id: I690cd1b9fe89afa9f58d9084e4473704a12f891d
Signed-off-by: Stefan Reinauer <reinauer@google.com>
Reviewed-on: https://chromium-review.googlesource.com/172276
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-by: Ronald Minnich <rminnich@chromium.org>
Commit-Queue: Stefan Reinauer <reinauer@chromium.org>
Tested-by: Stefan Reinauer <reinauer@chromium.org>

src/vendorcode/google/chromeos/chromeos.c

@@ -81,6 +81,13 @@ int recovery_mode_enabled(void)
 		vboot_enable_recovery();
 }
 
+#ifdef __PRE_RAM__
+void __attribute__((weak)) save_chromeos_gpios(void)
+{
+	// Can be implemented by a mainboard
+}
+#endif
+
 #if CONFIG_VBOOT_VERIFY_FIRMWARE
 void *vboot_get_payload(int *len)
 {

src/vendorcode/google/chromeos/chromeos.h

@@ -27,7 +27,7 @@ int get_developer_mode_switch(void);
 int get_recovery_mode_switch(void);
 int get_write_protect_state(void);
 #ifdef __PRE_RAM__
-void save_chromeos_gpios(void);
+void __attribute__((weak)) save_chromeos_gpios(void);
 #endif
 
 /* functions implemented in vbnv.c: */