diff --git a/include/linux/kernelcapi.h b/include/linux/kernelcapi.h
new file mode 100644
index 0000000..075fab5
--- /dev/null
+++ b/include/linux/kernelcapi.h
@@ -0,0 +1,120 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * $Id: kernelcapi.h,v 1.8.6.2 2001/02/07 11:31:31 kai Exp $
+ * 
+ * Kernel CAPI 2.0 Interface for Linux
+ * 
+ * (c) Copyright 1997 by Carsten Paeth (calle@calle.in-berlin.de)
+ * 
+ */
+#ifndef __KERNELCAPI_H__
+#define __KERNELCAPI_H__
+
+
+#include <linux/list.h>
+#include <linux/skbuff.h>
+#include <linux/workqueue.h>
+#include <linux/notifier.h>
+#include <uapi/linux/kernelcapi.h>
+
+struct capi20_appl {
+	u16 applid;
+	capi_register_params rparam;
+	void (*recv_message)(struct capi20_appl *ap, struct sk_buff *skb);
+	void *private;
+
+	/* internal to kernelcapi.o */
+	unsigned long nrecvctlpkt;
+	unsigned long nrecvdatapkt;
+	unsigned long nsentctlpkt;
+	unsigned long nsentdatapkt;
+	struct mutex recv_mtx;
+	struct sk_buff_head recv_queue;
+	struct work_struct recv_work;
+	int release_in_progress;
+};
+
+u16 capi20_isinstalled(void);
+u16 capi20_register(struct capi20_appl *ap);
+u16 capi20_release(struct capi20_appl *ap);
+u16 capi20_put_message(struct capi20_appl *ap, struct sk_buff *skb);
+u16 capi20_get_manufacturer(u32 contr, u8 buf[CAPI_MANUFACTURER_LEN]);
+u16 capi20_get_version(u32 contr, struct capi_version *verp);
+u16 capi20_get_serial(u32 contr, u8 serial[CAPI_SERIAL_LEN]);
+u16 capi20_get_profile(u32 contr, struct capi_profile *profp);
+int capi20_manufacturer(unsigned long cmd, void __user *data);
+
+#define CAPICTR_UP			0
+#define CAPICTR_DOWN			1
+
+int register_capictr_notifier(struct notifier_block *nb);
+int unregister_capictr_notifier(struct notifier_block *nb);
+
+#define CAPI_NOERROR                      0x0000
+
+#define CAPI_TOOMANYAPPLS		  0x1001
+#define CAPI_LOGBLKSIZETOSMALL	          0x1002
+#define CAPI_BUFFEXECEEDS64K 	          0x1003
+#define CAPI_MSGBUFSIZETOOSMALL	          0x1004
+#define CAPI_ANZLOGCONNNOTSUPPORTED	  0x1005
+#define CAPI_REGRESERVED		  0x1006
+#define CAPI_REGBUSY 		          0x1007
+#define CAPI_REGOSRESOURCEERR	          0x1008
+#define CAPI_REGNOTINSTALLED 	          0x1009
+#define CAPI_REGCTRLERNOTSUPPORTEXTEQUIP  0x100a
+#define CAPI_REGCTRLERONLYSUPPORTEXTEQUIP 0x100b
+
+#define CAPI_ILLAPPNR		          0x1101
+#define CAPI_ILLCMDORSUBCMDORMSGTOSMALL   0x1102
+#define CAPI_SENDQUEUEFULL		  0x1103
+#define CAPI_RECEIVEQUEUEEMPTY	          0x1104
+#define CAPI_RECEIVEOVERFLOW 	          0x1105
+#define CAPI_UNKNOWNNOTPAR		  0x1106
+#define CAPI_MSGBUSY 		          0x1107
+#define CAPI_MSGOSRESOURCEERR	          0x1108
+#define CAPI_MSGNOTINSTALLED 	          0x1109
+#define CAPI_MSGCTRLERNOTSUPPORTEXTEQUIP  0x110a
+#define CAPI_MSGCTRLERONLYSUPPORTEXTEQUIP 0x110b
+
+typedef enum {
+        CapiMessageNotSupportedInCurrentState = 0x2001,
+        CapiIllContrPlciNcci                  = 0x2002,
+        CapiNoPlciAvailable                   = 0x2003,
+        CapiNoNcciAvailable                   = 0x2004,
+        CapiNoListenResourcesAvailable        = 0x2005,
+        CapiNoFaxResourcesAvailable           = 0x2006,
+        CapiIllMessageParmCoding              = 0x2007,
+} RESOURCE_CODING_PROBLEM;
+
+typedef enum {
+        CapiB1ProtocolNotSupported                      = 0x3001,
+        CapiB2ProtocolNotSupported                      = 0x3002,
+        CapiB3ProtocolNotSupported                      = 0x3003,
+        CapiB1ProtocolParameterNotSupported             = 0x3004,
+        CapiB2ProtocolParameterNotSupported             = 0x3005,
+        CapiB3ProtocolParameterNotSupported             = 0x3006,
+        CapiBProtocolCombinationNotSupported            = 0x3007,
+        CapiNcpiNotSupported                            = 0x3008,
+        CapiCipValueUnknown                             = 0x3009,
+        CapiFlagsNotSupported                           = 0x300a,
+        CapiFacilityNotSupported                        = 0x300b,
+        CapiDataLengthNotSupportedByCurrentProtocol     = 0x300c,
+        CapiResetProcedureNotSupportedByCurrentProtocol = 0x300d,
+        CapiTeiAssignmentFailed                         = 0x300e,
+} REQUESTED_SERVICES_PROBLEM;
+
+typedef enum {
+	CapiSuccess                                     = 0x0000,
+	CapiSupplementaryServiceNotSupported            = 0x300e,
+	CapiRequestNotAllowedInThisState                = 0x3010,
+} SUPPLEMENTARY_SERVICE_INFO;
+
+typedef enum {
+	CapiProtocolErrorLayer1                         = 0x3301,
+	CapiProtocolErrorLayer2                         = 0x3302,
+	CapiProtocolErrorLayer3                         = 0x3303,
+	CapiTimeOut                                     = 0x3303, // SuppServiceReason
+	CapiCallGivenToOtherApplication                 = 0x3304,
+} CAPI_REASON;
+
+#endif				/* __KERNELCAPI_H__ */