Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/include/linux/mailbox/brcm-message.h b/include/linux/mailbox/brcm-message.h
index c20b484..18da821 100644
--- a/include/linux/mailbox/brcm-message.h
+++ b/include/linux/mailbox/brcm-message.h
@@ -1,10 +1,7 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
 /*
  *  Copyright (C) 2016 Broadcom
  *
- * 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.
- *
  * Common header for Broadcom mailbox messages which is shared across
  * Broadcom SoCs and Broadcom mailbox client drivers.
  */
diff --git a/include/linux/mailbox/mtk-cmdq-mailbox.h b/include/linux/mailbox/mtk-cmdq-mailbox.h
index ccb7342..e6f54ef 100644
--- a/include/linux/mailbox/mtk-cmdq-mailbox.h
+++ b/include/linux/mailbox/mtk-cmdq-mailbox.h
@@ -20,6 +20,9 @@
 #define CMDQ_WFE_WAIT			BIT(15)
 #define CMDQ_WFE_WAIT_VALUE		0x1
 
+/** cmdq event maximum */
+#define CMDQ_MAX_EVENT			0x3ff
+
 /*
  * CMDQ_CODE_MASK:
  *   set write mask
diff --git a/include/linux/mailbox/zynqmp-ipi-message.h b/include/linux/mailbox/zynqmp-ipi-message.h
new file mode 100644
index 0000000..9542b41
--- /dev/null
+++ b/include/linux/mailbox/zynqmp-ipi-message.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _LINUX_ZYNQMP_IPI_MESSAGE_H_
+#define _LINUX_ZYNQMP_IPI_MESSAGE_H_
+
+/**
+ * struct zynqmp_ipi_message - ZynqMP IPI message structure
+ * @len:  Length of message
+ * @data: message payload
+ *
+ * This is the structure for data used in mbox_send_message
+ * the maximum length of data buffer is fixed to 12 bytes.
+ * Client is supposed to be aware of this.
+ */
+struct zynqmp_ipi_message {
+	size_t len;
+	u8 data[0];
+};
+
+#endif /* _LINUX_ZYNQMP_IPI_MESSAGE_H_ */