v4.19.13 snapshot.
diff --git a/include/linux/libps2.h b/include/linux/libps2.h
new file mode 100644
index 0000000..5f18fe0
--- /dev/null
+++ b/include/linux/libps2.h
@@ -0,0 +1,64 @@
+#ifndef _LIBPS2_H
+#define _LIBPS2_H
+
+/*
+ * Copyright (C) 1999-2002 Vojtech Pavlik
+ * Copyright (C) 2004 Dmitry Torokhov
+ *
+ * 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.
+ */
+
+#include <linux/bitops.h>
+#include <linux/mutex.h>
+#include <linux/types.h>
+#include <linux/wait.h>
+
+#define PS2_CMD_SETSCALE11 0x00e6
+#define PS2_CMD_SETRES 0x10e8
+#define PS2_CMD_GETID 0x02f2
+#define PS2_CMD_RESET_BAT 0x02ff
+
+#define PS2_RET_BAT 0xaa
+#define PS2_RET_ID 0x00
+#define PS2_RET_ACK 0xfa
+#define PS2_RET_NAK 0xfe
+#define PS2_RET_ERR 0xfc
+
+#define PS2_FLAG_ACK BIT(0) /* Waiting for ACK/NAK */
+#define PS2_FLAG_CMD BIT(1) /* Waiting for a command to finish */
+#define PS2_FLAG_CMD1 BIT(2) /* Waiting for the first byte of command response */
+#define PS2_FLAG_WAITID BIT(3) /* Command executing is GET ID */
+#define PS2_FLAG_NAK BIT(4) /* Last transmission was NAKed */
+#define PS2_FLAG_ACK_CMD BIT(5) /* Waiting to ACK the command (first) byte */
+
+struct ps2dev {
+ struct serio *serio;
+
+ /* Ensures that only one command is executing at a time */
+ struct mutex cmd_mutex;
+
+ /* Used to signal completion from interrupt handler */
+ wait_queue_head_t wait;
+
+ unsigned long flags;
+ u8 cmdbuf[8];
+ u8 cmdcnt;
+ u8 nak;
+};
+
+void ps2_init(struct ps2dev *ps2dev, struct serio *serio);
+int ps2_sendbyte(struct ps2dev *ps2dev, u8 byte, unsigned int timeout);
+void ps2_drain(struct ps2dev *ps2dev, size_t maxbytes, unsigned int timeout);
+void ps2_begin_command(struct ps2dev *ps2dev);
+void ps2_end_command(struct ps2dev *ps2dev);
+int __ps2_command(struct ps2dev *ps2dev, u8 *param, unsigned int command);
+int ps2_command(struct ps2dev *ps2dev, u8 *param, unsigned int command);
+int ps2_sliced_command(struct ps2dev *ps2dev, u8 command);
+bool ps2_handle_ack(struct ps2dev *ps2dev, u8 data);
+bool ps2_handle_response(struct ps2dev *ps2dev, u8 data);
+void ps2_cmd_aborted(struct ps2dev *ps2dev);
+bool ps2_is_keyboard_id(u8 id);
+
+#endif /* _LIBPS2_H */