storage: allow auto-lock delay configuration

firmware/storage.c

@@ -173,8 +173,8 @@ bool storage_from_flash(void)
 		// added flags and needsBackup
 		old_storage_size = OLD_STORAGE_SIZE(flags);
 	} else if (version <= 9) {
-		// added u2froot
-		old_storage_size = OLD_STORAGE_SIZE(u2froot);
+		// added u2froot and auto_lock_delay_ms
+		old_storage_size = OLD_STORAGE_SIZE(auto_lock_delay_ms);
 	}
 
 	// erase newly added fields
@@ -868,6 +868,18 @@ void storage_setU2FCounter(uint32_t u2fcounter)
 	storageUpdate.u2f_counter = u2fcounter - storage_u2f_offset;
 }
 
+uint32_t storage_getAutoLockDelayMs()
+{
+	return storageRom->has_auto_lock_delay_ms ? storageRom->auto_lock_delay_ms : (10*60*1000U);
+}
+
+void storage_setAutoLockDelayMs(uint32_t auto_lock_delay_ms)
+{
+	storageUpdate.has_auto_lock_delay_ms = true;
+	auto_lock_delay_ms = MAX(auto_lock_delay_ms, 60*1000U);
+	storageUpdate.auto_lock_delay_ms = auto_lock_delay_ms;
+}
+
 void storage_wipe(void)
 {
 	session_clear(true);

firmware/storage.h

@@ -72,6 +72,7 @@ typedef struct _Storage {
     STORAGE_BOOL   (needs_backup)
     STORAGE_UINT32 (flags)
     STORAGE_NODE   (u2froot)
+    STORAGE_UINT32 (auto_lock_delay_ms)
 } Storage;
 
 extern Storage storageUpdate;
@@ -141,6 +142,9 @@ void storage_setNeedsBackup(bool needs_backup);
 void storage_applyFlags(uint32_t flags);
 uint32_t storage_getFlags(void);
 
+uint32_t storage_getAutoLockDelayMs(void);
+void storage_setAutoLockDelayMs(uint32_t auto_lock_delay_ms);
+
 void storage_wipe(void);
 
 extern char storage_uuid_str[25];

firmware/trezor.c

@@ -74,9 +74,9 @@ void check_lock_screen(void)
 		}
 	}
 
-	// if homescreen is shown for longer than 10 minutes, lock too
+	// if homescreen is shown for too long
 	if (layoutLast == layoutHome) {
-		if ((timer_ms() - system_millis_lock_start) >= 600000) {
+		if ((timer_ms() - system_millis_lock_start) >= storage_getAutoLockDelayMs()) {
 			// lock the screen
 			session_clear(true);
 			layoutScreensaver();