Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/arch/powerpc/include/asm/time.h b/arch/powerpc/include/asm/time.h
index b80d492..08dbe3e 100644
--- a/arch/powerpc/include/asm/time.h
+++ b/arch/powerpc/include/asm/time.h
@@ -1,13 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
 /*
  * Common time prototypes and such for all ppc machines.
  *
  * Written by Cort Dougan (cort@cs.nmt.edu) to merge
  * Paul Mackerras' version and mine for PReP and Pmac.
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version
- * 2 of the License, or (at your option) any later version.
  */
 
 #ifndef __POWERPC_TIME_H
@@ -36,6 +32,8 @@
 extern unsigned long ppc_tb_freq;
 #define DEFAULT_TB_FREQ		125000000UL
 
+extern bool tb_invalid;
+
 struct div_result {
 	u64 result_high;
 	u64 result_low;
@@ -43,11 +41,7 @@
 
 /* Accessor functions for the timebase (RTC on 601) registers. */
 /* If one day CONFIG_POWER is added just define __USE_RTC as 1 */
-#ifdef CONFIG_6xx
-#define __USE_RTC()	(cpu_has_feature(CPU_FTR_USE_RTC))
-#else
-#define __USE_RTC()	0
-#endif
+#define __USE_RTC()	(IS_ENABLED(CONFIG_PPC_BOOK3S_601))
 
 #ifdef CONFIG_PPC64