Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/include/soc/arc/aux.h b/include/soc/arc/aux.h
index 8c3fb13..e223c4f 100644
--- a/include/soc/arc/aux.h
+++ b/include/soc/arc/aux.h
@@ -1,10 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
 /*
  * Copyright (C) 2016-2017 Synopsys, Inc. (www.synopsys.com)
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- *
  */
 
 #ifndef __SOC_ARC_AUX_H__
diff --git a/include/soc/arc/mcip.h b/include/soc/arc/mcip.h
index a91f251..d1a93c7 100644
--- a/include/soc/arc/mcip.h
+++ b/include/soc/arc/mcip.h
@@ -1,11 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
 /*
  * ARConnect IP Support (Multi core enabler: Cross core IPI, RTC ...)
  *
  * Copyright (C) 2014-15 Synopsys, Inc. (www.synopsys.com)
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
  */
 
 #ifndef __SOC_ARC_MCIP_H
@@ -49,7 +46,9 @@
 #define CMD_IDU_ENABLE			0x71
 #define CMD_IDU_DISABLE			0x72
 #define CMD_IDU_SET_MODE		0x74
+#define CMD_IDU_READ_MODE		0x75
 #define CMD_IDU_SET_DEST		0x76
+#define CMD_IDU_ACK_CIRQ		0x79
 #define CMD_IDU_SET_MASK		0x7C
 
 #define IDU_M_TRIG_LEVEL		0x0
@@ -122,4 +121,13 @@
 	__mcip_cmd(cmd, param);
 }
 
+/*
+ * Read MCIP register
+ */
+static inline unsigned int __mcip_cmd_read(unsigned int cmd, unsigned int param)
+{
+	__mcip_cmd(cmd, param);
+	return read_aux_reg(ARC_REG_MCIP_READBACK);
+}
+
 #endif
diff --git a/include/soc/arc/timers.h b/include/soc/arc/timers.h
index a20ed2f..7ecde3b 100644
--- a/include/soc/arc/timers.h
+++ b/include/soc/arc/timers.h
@@ -1,9 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
 /*
  * Copyright (C) 2016-17 Synopsys, Inc. (www.synopsys.com)
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
  */
 
 #ifndef __SOC_ARC_TIMERS_H