diff --git a/drivers/infiniband/ulp/rtrs/rtrs.h b/drivers/infiniband/ulp/rtrs/rtrs.h
new file mode 100644
index 000000000000..5b55ad163505
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+++ b/drivers/infiniband/ulp/rtrs/rtrs.h
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+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * InfiniBand Transport Layer
+ *
+ * Copyright (c) 2014 - 2017 ProfitBricks GmbH. All rights reserved.
+ * Authors: Fabian Holler <mail@fholler.de>
+ *          Jack Wang <jinpu.wang@profitbricks.com>
+ *          Kleber Souza <kleber.souza@profitbricks.com>
+ *          Danil Kipnis <danil.kipnis@profitbricks.com>
+ *          Roman Penyaev <roman.penyaev@profitbricks.com>
+ *          Milind Dumbare <Milind.dumbare@gmail.com>
+ *
+ * Copyright (c) 2017 - 2018 ProfitBricks GmbH. All rights reserved.
+ * Authors: Danil Kipnis <danil.kipnis@profitbricks.com>
+ *          Roman Penyaev <roman.penyaev@profitbricks.com>
+ *
+ * Copyright (c) 2018 - 2019 1&1 IONOS Cloud GmbH. All rights reserved.
+ * Authors: Roman Penyaev <roman.penyaev@profitbricks.com>
+ *          Jinpu Wang <jinpu.wang@cloud.ionos.com>
+ *          Danil Kipnis <danil.kipnis@cloud.ionos.com>
+ */
+
+/* Copyright (c) 2019 1&1 IONOS SE. All rights reserved.
+ * Authors: Jack Wang <jinpu.wang@cloud.ionos.com>
+ *          Danil Kipnis <danil.kipnis@cloud.ionos.com>
+ *          Guoqing Jiang <guoqing.jiang@cloud.ionos.com>
+ *          Lutz Pogrell <lutz.pogrell@cloud.ionos.com>
+ */
+#ifndef RTRS_H
+#define RTRS_H
+
+#include <linux/socket.h>
+#include <linux/scatterlist.h>
+
+struct rtrs_permit;
+struct rtrs_clt;
+struct rtrs_srv_ctx;
+struct rtrs_srv;
+struct rtrs_srv_op;
+
+/*
+ * Here goes RTRS client API
+ */
+
+/**
+ * enum rtrs_clt_link_ev - Events about connectivity state of a client
+ * @RTRS_CLT_LINK_EV_RECONNECTED	Client was reconnected.
+ * @RTRS_CLT_LINK_EV_DISCONNECTED	Client was disconnected.
+ */
+enum rtrs_clt_link_ev {
+	RTRS_CLT_LINK_EV_RECONNECTED,
+	RTRS_CLT_LINK_EV_DISCONNECTED,
+};
+
+/**
+ * Source and destination address of a path to be established
+ */
+struct rtrs_addr {
+	struct sockaddr_storage *src;
+	struct sockaddr_storage *dst;
+};
+
+typedef void (link_clt_ev_fn)(void *priv, enum rtrs_clt_link_ev ev);
+/**
+ * rtrs_clt_open() - Open a session to an RTRS server
+ * @priv: User supplied private data.
+ * @link_ev: Event notification for connection state changes
+ *	@priv: User supplied data that was passed to rtrs_clt_open()
+ *	@ev: Occurred event
+ * @sessname: name of the session
+ * @paths: Paths to be established defined by their src and dst addresses
+ * @path_cnt: Number of elemnts in the @paths array
+ * @port: port to be used by the RTRS session
+ * @pdu_sz: Size of extra payload which can be accessed after permit allocation.
+ * @max_inflight_msg: Max. number of parallel inflight messages for the session
+ * @max_segments: Max. number of segments per IO request
+ * @reconnect_delay_sec: time between reconnect tries
+ * @max_reconnect_attempts: Number of times to reconnect on error before giving
+ *			    up, 0 for * disabled, -1 for forever
+ *
+ * Starts session establishment with the rtrs_server. The function can block
+ * up to ~2000ms until it returns.
+ *
+ * Return a valid pointer on success otherwise PTR_ERR.
+ */
+struct rtrs_clt *rtrs_clt_open(void *priv, link_clt_ev_fn *link_ev,
+				 const char *sessname,
+				 const struct rtrs_addr *paths,
+				 size_t path_cnt, short port,
+				 size_t pdu_sz, u8 reconnect_delay_sec,
+				 u16 max_segments,
+				 s16 max_reconnect_attempts);
+
+/**
+ * rtrs_clt_close() - Close a session
+ * @sess: Session handle. Session is freed on return.
+ */
+void rtrs_clt_close(struct rtrs_clt *sess);
+
+/**
+ * rtrs_permit_from_pdu() - converts opaque pdu pointer to rtrs_permit
+ * @pdu: opaque pointer
+ */
+struct rtrs_permit *rtrs_permit_from_pdu(void *pdu);
+
+/**
+ * rtrs_permit_to_pdu() - converts rtrs_permit to opaque pdu pointer
+ * @permit: RTRS permit pointer
+ */
+void *rtrs_permit_to_pdu(struct rtrs_permit *permit);
+
+enum {
+	RTRS_PERMIT_NOWAIT = 0,
+	RTRS_PERMIT_WAIT   = 1,
+};
+
+/**
+ * enum rtrs_clt_con_type() type of ib connection to use with a given permit
+ * @USR_CON - use connection reserved vor "service" messages
+ * @IO_CON - use a connection reserved for IO
+ */
+enum rtrs_clt_con_type {
+	RTRS_USR_CON,
+	RTRS_IO_CON
+};
+
+/**
+ * rtrs_clt_get_permit() - allocates permit for future RDMA operation
+ * @sess:	Current session
+ * @con_type:	Type of connection to use with the permit
+ * @wait:	Wait type
+ *
+ * Description:
+ *    Allocates permit for the following RDMA operation.  Permit is used
+ *    to preallocate all resources and to propagate memory pressure
+ *    up earlier.
+ *
+ * Context:
+ *    Can sleep if @wait == RTRS_TAG_WAIT
+ */
+struct rtrs_permit *rtrs_clt_get_permit(struct rtrs_clt *sess,
+				    enum rtrs_clt_con_type con_type,
+				    int wait);
+
+/**
+ * rtrs_clt_put_permit() - puts allocated permit
+ * @sess:	Current session
+ * @permit:	Permit to be freed
+ *
+ * Context:
+ *    Does not matter
+ */
+void rtrs_clt_put_permit(struct rtrs_clt *sess, struct rtrs_permit *permit);
+
+typedef void (rtrs_conf_fn)(void *priv, int errno);
+/**
+ * rtrs_clt_request() - Request data transfer to/from server via RDMA.
+ *
+ * @dir:	READ/WRITE
+ * @conf:	callback function to be called as confirmation
+ * @sess:	Session
+ * @permit:	Preallocated permit
+ * @priv:	User provided data, passed back with corresponding
+ *		@(conf) confirmation.
+ * @vec:	Message that is send to server together with the request.
+ *		Sum of len of all @vec elements limited to <= IO_MSG_SIZE.
+ *		Since the msg is copied internally it can be allocated on stack.
+ * @nr:		Number of elements in @vec.
+ * @len:	length of data send to/from server
+ * @sg:		Pages to be sent/received to/from server.
+ * @sg_cnt:	Number of elements in the @sg
+ *
+ * Return:
+ * 0:		Success
+ * <0:		Error
+ *
+ * On dir=READ rtrs client will request a data transfer from Server to client.
+ * The data that the server will respond with will be stored in @sg when
+ * the user receives an %RTRS_CLT_RDMA_EV_RDMA_REQUEST_WRITE_COMPL event.
+ * On dir=WRITE rtrs client will rdma write data in sg to server side.
+ */
+int rtrs_clt_request(int dir, rtrs_conf_fn *conf, struct rtrs_clt *sess,
+		      struct rtrs_permit *permit, void *priv,
+		      const struct kvec *vec, size_t nr, size_t len,
+		      struct scatterlist *sg, unsigned int sg_cnt);
+
+/**
+ * rtrs_attrs - RTRS session attributes
+ */
+struct rtrs_attrs {
+	u32	queue_depth;
+	u32	max_io_size;
+	u8	sessname[NAME_MAX];
+	struct kobject *sess_kobj;
+};
+
+/**
+ * rtrs_clt_query() - queries RTRS session attributes
+ *
+ * Returns:
+ *    0 on success
+ *    -ECOMM		no connection to the server
+ */
+int rtrs_clt_query(struct rtrs_clt *sess, struct rtrs_attrs *attr);
+
+/*
+ * Here goes RTRS server API
+ */
+
+/**
+ * enum rtrs_srv_link_ev - Server link events
+ * @RTRS_SRV_LINK_EV_CONNECTED:	Connection from client established
+ * @RTRS_SRV_LINK_EV_DISCONNECTED:	Connection was disconnected, all
+ *					connection RTRS resources were freed.
+ */
+enum rtrs_srv_link_ev {
+	RTRS_SRV_LINK_EV_CONNECTED,
+	RTRS_SRV_LINK_EV_DISCONNECTED,
+};
+
+/**
+ * rdma_ev_fn():	Event notification for RDMA operations
+ *			If the callback returns a value != 0, an error message
+ *			for the data transfer will be sent to the client.
+
+ *	@sess:		Session
+ *	@priv:		Private data set by rtrs_srv_set_sess_priv()
+ *	@id:		internal RTRS operation id
+ *	@dir:		READ/WRITE
+ *	@data:		Pointer to (bidirectional) rdma memory area:
+ *			- in case of %RTRS_SRV_RDMA_EV_RECV contains
+ *			data sent by the client
+ *			- in case of %RTRS_SRV_RDMA_EV_WRITE_REQ points to the
+ *			memory area where the response is to be written to
+ *	@datalen:	Size of the memory area in @data
+ *	@usr:		The extra user message sent by the client (%vec)
+ *	@usrlen:	Size of the user message
+ */
+typedef int (rdma_ev_fn)(struct rtrs_srv *sess, void *priv,
+			 struct rtrs_srv_op *id, int dir,
+			 void *data, size_t datalen, const void *usr,
+			 size_t usrlen);
+
+/**
+ * link_ev_fn():	Events about connective state changes
+ *			If the callback returns != 0 and the event
+ *			%RTRS_SRV_LINK_EV_CONNECTED the corresponding session
+ *			will be destroyed.
+ *	@sess:		Session
+ *	@ev:		event
+ *	@priv:		Private data from user if previously set with
+ *			rtrs_srv_set_sess_priv()
+ */
+typedef int (link_ev_fn)(struct rtrs_srv *sess, enum rtrs_srv_link_ev ev,
+			 void *priv);
+
+/**
+ * rtrs_srv_open() - open RTRS server context
+ * @ops:		callback functions
+ *
+ * Creates server context with specified callbacks.
+ *
+ * Return a valid pointer on success otherwise PTR_ERR.
+ */
+struct rtrs_srv_ctx *rtrs_srv_open(rdma_ev_fn *rdma_ev, link_ev_fn *link_ev,
+				     unsigned int port);
+
+/**
+ * rtrs_srv_close() - close RTRS server context
+ * @ctx: pointer to server context
+ *
+ * Closes RTRS server context with all client sessions.
+ */
+void rtrs_srv_close(struct rtrs_srv_ctx *ctx);
+
+/**
+ * rtrs_srv_resp_rdma() - Finish an RDMA request
+ *
+ * @id:		Internal RTRS operation identifier
+ * @errno:	Response Code send to the other side for this operation.
+ *		0 = success, <=0 error
+ *
+ * Finish a RDMA operation. A message is sent to the client and the
+ * corresponding memory areas will be released.
+ */
+void rtrs_srv_resp_rdma(struct rtrs_srv_op *id, int errno);
+
+/**
+ * rtrs_srv_set_sess_priv() - Set private pointer in rtrs_srv.
+ * @sess:	Session
+ * @priv:	The private pointer that is associated with the session.
+ */
+void rtrs_srv_set_sess_priv(struct rtrs_srv *sess, void *priv);
+
+/**
+ * rtrs_srv_get_sess_qdepth() - Get rtrs_srv qdepth.
+ * @sess:	Session
+ */
+int rtrs_srv_get_queue_depth(struct rtrs_srv *sess);
+
+/**
+ * rtrs_srv_get_sess_name() - Get rtrs_srv peer hostname.
+ * @sess:	Session
+ * @sessname:	Sessname buffer
+ * @len:	Length of sessname buffer
+ */
+int rtrs_srv_get_sess_name(struct rtrs_srv *sess, char *sessname, size_t len);
+
+/**
+ * rtrs_addr_to_sockaddr() - convert path string "src,dst" to sockaddreses
+ * @str		string containing source and destination addr of a path
+ *		separated by comma. I.e. "ip:1.1.1.1,ip:1.1.1.2". If str
+ *		contains only one address it's considered to be destination.
+ * @len		string length
+ * @addr->dst	will be set to the destination sockadddr.
+ * @addr->src	will be set to the source address or to NULL
+ *		if str doesn't contain any sorce address.
+ *
+ * Returns zero if conversion successful. Non-zero otherwise.
+ */
+int rtrs_addr_to_sockaddr(const char *str, size_t len, short port,
+			   struct rtrs_addr *addr);
+
+/**
+ * sockaddr_to_str() - convert sockaddr to a string.
+ * @addr	the sockadddr structure to be converted.
+ * @buf		string containing socket addr.
+ * @len		string length.
+ *
+ * The return value is the number of characters written into buf not
+ * including the trailing '\0'. If len is == 0 the function returns 0..
+ */
+int sockaddr_to_str(const struct sockaddr *addr, char *buf, size_t len);
+#endif
