usbdebug: Fix migration to ramstage

On entry to ramstage CBMEM is looked for a copy of an already initialized
EHCI debug dongle state. If a copy is found, it contained the state before
CAR migration and the USB protocol data toggle can be out of sync. It's an
even/odd kind of a parity check, so roughly every other build would
show the problem as invalid first line: 'ug found in CBMEM.'

After CAR migration, re-direct the state changes to correct CBMEM table.

Change-Id: I7c54e76ce29af5c8ee5e9ce6fd3dc6bdf700dcf1
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/7206
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Tested-by: build bot (Jenkins)
diff --git a/src/drivers/usb/ehci_debug.c b/src/drivers/usb/ehci_debug.c
index c60fbaa..5a62999 100644
--- a/src/drivers/usb/ehci_debug.c
+++ b/src/drivers/usb/ehci_debug.c
@@ -96,10 +96,14 @@
 #define DBGP_MAX_PACKET		8
 
 static struct ehci_debug_info glob_dbg_info CAR_GLOBAL;
+static struct ehci_debug_info * glob_dbg_info_p CAR_GLOBAL;
 
 static inline struct ehci_debug_info *dbgp_ehci_info(void)
 {
-	return car_get_var_ptr(&glob_dbg_info);
+	if (car_get_var(glob_dbg_info_p) == NULL)
+		car_set_var(glob_dbg_info_p, &glob_dbg_info);
+
+	return car_get_var(glob_dbg_info_p);
 }
 
 static int dbgp_wait_until_complete(struct ehci_dbg_port *ehci_debug)
@@ -905,6 +909,7 @@
 		return;
 
 	memcpy(dbg_info_cbmem, dbg_info, sizeof(*dbg_info));
+	car_set_var(glob_dbg_info_p, dbg_info_cbmem);
 }
 CAR_MIGRATE(migrate_ehci_debug);
 #endif