Document and decompile more of frontier pass.

src/trainer_card.c

@@ -8,6 +8,7 @@
 #include "link.h"
 #include "bg.h"
 #include "sound.h"
+#include "frontier_pass.h"
 #include "overworld.h"
 #include "menu.h"
 #include "text.h"
@@ -90,7 +91,6 @@ struct TrainerCardData
 
 //external functions
 extern u8 sub_80D30A0(u16);
-extern void sub_80C5868(void);
 
 // EWRAM
 EWRAM_DATA static struct TrainerCardData *sData = NULL;
@@ -1754,7 +1754,7 @@ void ShowPlayerTrainerCard(void (*callback)(void))
 {
     sData = AllocZeroed(sizeof(*sData));
     sData->callback2 = callback;
-    if (callback == sub_80C5868)
+    if (callback == CB2_ReshowFrontierPass)
         sData->var_52C = 0x7FFF;
     else
         sData->var_52C = 0;