misc: mic: SCIF header file and IOCTL interface

This patch introduces the SCIF documentation in the header file
and describes the IOCTL interface for user mode. mic_overview.txt
is updated with documentation on SCIF and a new document
describing SCIF in more details is available in scif_overview.txt.

Reviewed-by: Nikhil Rao <nikhil.rao@intel.com>
Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Signed-off-by: Sudeep Dutt <sudeep.dutt@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 993 insertions, 0 deletions

diff --git a/include/linux/scif.h b/include/linux/scif.h
new file mode 100644
index 000000000000..44f4f3898bbe
--- /dev/null
+++ b/include/linux/scif.h
@@ -0,0 +1,993 @@
+/*
+ * Intel MIC Platform Software Stack (MPSS)
+ *
+ * This file is provided under a dual BSD/GPLv2 license.  When using or
+ * redistributing this file, you may do so under either license.
+ *
+ * GPL LICENSE SUMMARY
+ *
+ * Copyright(c) 2014 Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * BSD LICENSE
+ *
+ * Copyright(c) 2014 Intel Corporation.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in
+ *   the documentation and/or other materials provided with the
+ *   distribution.
+ * * Neither the name of Intel Corporation nor the names of its
+ *   contributors may be used to endorse or promote products derived
+ *   from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Intel SCIF driver.
+ *
+ */
+#ifndef __SCIF_H__
+#define __SCIF_H__
+
+#include <linux/types.h>
+#include <linux/poll.h>
+#include <linux/scif_ioctl.h>
+
+#define SCIF_ACCEPT_SYNC	1
+#define SCIF_SEND_BLOCK		1
+#define SCIF_RECV_BLOCK		1
+
+enum {
+	SCIF_PROT_READ = (1 << 0),
+	SCIF_PROT_WRITE = (1 << 1)
+};
+
+enum {
+	SCIF_MAP_FIXED = 0x10,
+	SCIF_MAP_KERNEL	= 0x20,
+};
+
+enum {
+	SCIF_FENCE_INIT_SELF = (1 << 0),
+	SCIF_FENCE_INIT_PEER = (1 << 1),
+	SCIF_SIGNAL_LOCAL = (1 << 4),
+	SCIF_SIGNAL_REMOTE = (1 << 5)
+};
+
+enum {
+	SCIF_RMA_USECPU = (1 << 0),
+	SCIF_RMA_USECACHE = (1 << 1),
+	SCIF_RMA_SYNC = (1 << 2),
+	SCIF_RMA_ORDERED = (1 << 3)
+};
+
+/* End of SCIF Admin Reserved Ports */
+#define SCIF_ADMIN_PORT_END	1024
+
+/* End of SCIF Reserved Ports */
+#define SCIF_PORT_RSVD		1088
+
+typedef struct scif_endpt *scif_epd_t;
+
+#define SCIF_OPEN_FAILED ((scif_epd_t)-1)
+#define SCIF_REGISTER_FAILED ((off_t)-1)
+#define SCIF_MMAP_FAILED ((void *)-1)
+
+/**
+ * scif_open() - Create an endpoint
+ *
+ * Return:
+ * Upon successful completion, scif_open() returns an endpoint descriptor to
+ * be used in subsequent SCIF functions calls to refer to that endpoint;
+ * otherwise in user mode SCIF_OPEN_FAILED (that is ((scif_epd_t)-1)) is
+ * returned and errno is set to indicate the error; in kernel mode a NULL
+ * scif_epd_t is returned.
+ *
+ * Errors:
+ * ENOMEM - Insufficient kernel memory was available
+ */
+scif_epd_t scif_open(void);
+
+/**
+ * scif_bind() - Bind an endpoint to a port
+ * @epd:	endpoint descriptor
+ * @pn:		port number
+ *
+ * scif_bind() binds endpoint epd to port pn, where pn is a port number on the
+ * local node. If pn is zero, a port number greater than or equal to
+ * SCIF_PORT_RSVD is assigned and returned. Each endpoint may be bound to
+ * exactly one local port. Ports less than 1024 when requested can only be bound
+ * by system (or root) processes or by processes executed by privileged users.
+ *
+ * Return:
+ * Upon successful completion, scif_bind() returns the port number to which epd
+ * is bound; otherwise in user mode -1 is returned and errno is set to
+ * indicate the error; in kernel mode the negative of one of the following
+ * errors is returned.
+ *
+ * Errors:
+ * EBADF, ENOTTY - epd is not a valid endpoint descriptor
+ * EINVAL - the endpoint or the port is already bound
+ * EISCONN - The endpoint is already connected
+ * ENOSPC - No port number available for assignment
+ * EACCES - The port requested is protected and the user is not the superuser
+ */
+int scif_bind(scif_epd_t epd, u16 pn);
+
+/**
+ * scif_listen() - Listen for connections on an endpoint
+ * @epd:	endpoint descriptor
+ * @backlog:	maximum pending connection requests
+ *
+ * scif_listen() marks the endpoint epd as a listening endpoint - that is, as
+ * an endpoint that will be used to accept incoming connection requests. Once
+ * so marked, the endpoint is said to be in the listening state and may not be
+ * used as the endpoint of a connection.
+ *
+ * The endpoint, epd, must have been bound to a port.
+ *
+ * The backlog argument defines the maximum length to which the queue of
+ * pending connections for epd may grow. If a connection request arrives when
+ * the queue is full, the client may receive an error with an indication that
+ * the connection was refused.
+ *
+ * Return:
+ * Upon successful completion, scif_listen() returns 0; otherwise in user mode
+ * -1 is returned and errno is set to indicate the error; in kernel mode the
+ * negative of one of the following errors is returned.
+ *
+ * Errors:
+ * EBADF, ENOTTY - epd is not a valid endpoint descriptor
+ * EINVAL - the endpoint is not bound to a port
+ * EISCONN - The endpoint is already connected or listening
+ */
+int scif_listen(scif_epd_t epd, int backlog);
+
+/**
+ * scif_connect() - Initiate a connection on a port
+ * @epd:	endpoint descriptor
+ * @dst:	global id of port to which to connect
+ *
+ * The scif_connect() function requests the connection of endpoint epd to remote
+ * port dst. If the connection is successful, a peer endpoint, bound to dst, is
+ * created on node dst.node. On successful return, the connection is complete.
+ *
+ * If the endpoint epd has not already been bound to a port, scif_connect()
+ * will bind it to an unused local port.
+ *
+ * A connection is terminated when an endpoint of the connection is closed,
+ * either explicitly by scif_close(), or when a process that owns one of the
+ * endpoints of the connection is terminated.
+ *
+ * In user space, scif_connect() supports an asynchronous connection mode
+ * if the application has set the O_NONBLOCK flag on the endpoint via the
+ * fcntl() system call. Setting this flag will result in the calling process
+ * not to wait during scif_connect().
+ *
+ * Return:
+ * Upon successful completion, scif_connect() returns the port ID to which the
+ * endpoint, epd, is bound; otherwise in user mode -1 is returned and errno is
+ * set to indicate the error; in kernel mode the negative of one of the
+ * following errors is returned.
+ *
+ * Errors:
+ * EBADF, ENOTTY - epd is not a valid endpoint descriptor
+ * ECONNREFUSED - The destination was not listening for connections or refused
+ * the connection request
+ * EINVAL - dst.port is not a valid port ID
+ * EISCONN - The endpoint is already connected
+ * ENOMEM - No buffer space is available
+ * ENODEV - The destination node does not exist, or the node is lost or existed,
+ * but is not currently in the network since it may have crashed
+ * ENOSPC - No port number available for assignment
+ * EOPNOTSUPP - The endpoint is listening and cannot be connected
+ */
+int scif_connect(scif_epd_t epd, struct scif_port_id *dst);
+
+/**
+ * scif_accept() - Accept a connection on an endpoint
+ * @epd:	endpoint descriptor
+ * @peer:	global id of port to which connected
+ * @newepd:	new connected endpoint descriptor
+ * @flags:	flags
+ *
+ * The scif_accept() call extracts the first connection request from the queue
+ * of pending connections for the port on which epd is listening. scif_accept()
+ * creates a new endpoint, bound to the same port as epd, and allocates a new
+ * SCIF endpoint descriptor, returned in newepd, for the endpoint. The new
+ * endpoint is connected to the endpoint through which the connection was
+ * requested. epd is unaffected by this call, and remains in the listening
+ * state.
+ *
+ * On successful return, peer holds the global port identifier (node id and
+ * local port number) of the port which requested the connection.
+ *
+ * A connection is terminated when an endpoint of the connection is closed,
+ * either explicitly by scif_close(), or when a process that owns one of the
+ * endpoints of the connection is terminated.
+ *
+ * The number of connections that can (subsequently) be accepted on epd is only
+ * limited by system resources (memory).
+ *
+ * The flags argument is formed by OR'ing together zero or more of the
+ * following values.
+ * SCIF_ACCEPT_SYNC - block until a connection request is presented. If
+ *			SCIF_ACCEPT_SYNC is not in flags, and no pending
+ *			connections are present on the queue, scif_accept()
+ *			fails with an EAGAIN error
+ *
+ * In user mode, the select() and poll() functions can be used to determine
+ * when there is a connection request. In kernel mode, the scif_poll()
+ * function may be used for this purpose. A readable event will be delivered
+ * when a connection is requested.
+ *
+ * Return:
+ * Upon successful completion, scif_accept() returns 0; otherwise in user mode
+ * -1 is returned and errno is set to indicate the error; in kernel mode the
+ *	negative of one of the following errors is returned.
+ *
+ * Errors:
+ * EAGAIN - SCIF_ACCEPT_SYNC is not set and no connections are present to be
+ * accepted or SCIF_ACCEPT_SYNC is not set and remote node failed to complete
+ * its connection request
+ * EBADF, ENOTTY - epd is not a valid endpoint descriptor
+ * EINTR - Interrupted function
+ * EINVAL - epd is not a listening endpoint, or flags is invalid, or peer is
+ * NULL, or newepd is NULL
+ * ENODEV - The requesting node is lost or existed, but is not currently in the
+ * network since it may have crashed
+ * ENOMEM - Not enough space
+ * ENOENT - Secondary part of epd registration failed
+ */
+int scif_accept(scif_epd_t epd, struct scif_port_id *peer, scif_epd_t
+		*newepd, int flags);
+
+/**
+ * scif_close() - Close an endpoint
+ * @epd:	endpoint descriptor
+ *
+ * scif_close() closes an endpoint and performs necessary teardown of
+ * facilities associated with that endpoint.
+ *
+ * If epd is a listening endpoint then it will no longer accept connection
+ * requests on the port to which it is bound. Any pending connection requests
+ * are rejected.
+ *
+ * If epd is a connected endpoint, then its peer endpoint is also closed. RMAs
+ * which are in-process through epd or its peer endpoint will complete before
+ * scif_close() returns. Registered windows of the local and peer endpoints are
+ * released as if scif_unregister() was called against each window.
+ *
+ * Closing a SCIF endpoint does not affect local registered memory mapped by
+ * a SCIF endpoint on a remote node. The local memory remains mapped by the peer
+ * SCIF endpoint explicitly removed by calling munmap(..) by the peer.
+ *
+ * If the peer endpoint's receive queue is not empty at the time that epd is
+ * closed, then the peer endpoint can be passed as the endpoint parameter to
+ * scif_recv() until the receive queue is empty.
+ *
+ * epd is freed and may no longer be accessed.
+ *
+ * Return:
+ * Upon successful completion, scif_close() returns 0; otherwise in user mode
+ * -1 is returned and errno is set to indicate the error; in kernel mode the
+ * negative of one of the following errors is returned.
+ *
+ * Errors:
+ * EBADF, ENOTTY - epd is not a valid endpoint descriptor
+ */
+int scif_close(scif_epd_t epd);
+
+/**
+ * scif_send() - Send a message
+ * @epd:	endpoint descriptor
+ * @msg:	message buffer address
+ * @len:	message length
+ * @flags:	blocking mode flags
+ *
+ * scif_send() sends data to the peer of endpoint epd. Up to len bytes of data
+ * are copied from memory starting at address msg. On successful execution the
+ * return value of scif_send() is the number of bytes that were sent, and is
+ * zero if no bytes were sent because len was zero. scif_send() may be called
+ * only when the endpoint is in a connected state.
+ *
+ * If a scif_send() call is non-blocking, then it sends only those bytes which
+ * can be sent without waiting, up to a maximum of len bytes.
+ *
+ * If a scif_send() call is blocking, then it normally returns after sending
+ * all len bytes. If a blocking call is interrupted or the connection is
+ * reset, the call is considered successful if some bytes were sent or len is
+ * zero, otherwise the call is considered unsuccessful.
+ *
+ * In user mode, the select() and poll() functions can be used to determine
+ * when the send queue is not full. In kernel mode, the scif_poll() function
+ * may be used for this purpose.
+ *
+ * It is recommended that scif_send()/scif_recv() only be used for short
+ * control-type message communication between SCIF endpoints. The SCIF RMA
+ * APIs are expected to provide better performance for transfer sizes of
+ * 1024 bytes or longer for the current MIC hardware and software
+ * implementation.
+ *
+ * scif_send() will block until the entire message is sent if SCIF_SEND_BLOCK
+ * is passed as the flags argument.
+ *
+ * Return:
+ * Upon successful completion, scif_send() returns the number of bytes sent;
+ * otherwise in user mode -1 is returned and errno is set to indicate the
+ * error; in kernel mode the negative of one of the following errors is
+ * returned.
+ *
+ * Errors:
+ * EBADF, ENOTTY - epd is not a valid endpoint descriptor
+ * ECONNRESET - Connection reset by peer
+ * EFAULT - An invalid address was specified for a parameter
+ * EINVAL - flags is invalid, or len is negative
+ * ENODEV - The remote node is lost or existed, but is not currently in the
+ * network since it may have crashed
+ * ENOMEM - Not enough space
+ * ENOTCONN - The endpoint is not connected
+ */
+int scif_send(scif_epd_t epd, void *msg, int len, int flags);
+
+/**
+ * scif_recv() - Receive a message
+ * @epd:	endpoint descriptor
+ * @msg:	message buffer address
+ * @len:	message buffer length
+ * @flags:	blocking mode flags
+ *
+ * scif_recv() receives data from the peer of endpoint epd. Up to len bytes of
+ * data are copied to memory starting at address msg. On successful execution
+ * the return value of scif_recv() is the number of bytes that were received,
+ * and is zero if no bytes were received because len was zero. scif_recv() may
+ * be called only when the endpoint is in a connected state.
+ *
+ * If a scif_recv() call is non-blocking, then it receives only those bytes
+ * which can be received without waiting, up to a maximum of len bytes.
+ *
+ * If a scif_recv() call is blocking, then it normally returns after receiving
+ * all len bytes. If the blocking call was interrupted due to a disconnection,
+ * subsequent calls to scif_recv() will copy all bytes received upto the point
+ * of disconnection.
+ *
+ * In user mode, the select() and poll() functions can be used to determine
+ * when data is available to be received. In kernel mode, the scif_poll()
+ * function may be used for this purpose.
+ *
+ * It is recommended that scif_send()/scif_recv() only be used for short
+ * control-type message communication between SCIF endpoints. The SCIF RMA
+ * APIs are expected to provide better performance for transfer sizes of
+ * 1024 bytes or longer for the current MIC hardware and software
+ * implementation.
+ *
+ * scif_recv() will block until the entire message is received if
+ * SCIF_RECV_BLOCK is passed as the flags argument.
+ *
+ * Return:
+ * Upon successful completion, scif_recv() returns the number of bytes
+ * received; otherwise in user mode -1 is returned and errno is set to
+ * indicate the error; in kernel mode the negative of one of the following
+ * errors is returned.
+ *
+ * Errors:
+ * EAGAIN - The destination node is returning from a low power state
+ * EBADF, ENOTTY - epd is not a valid endpoint descriptor
+ * ECONNRESET - Connection reset by peer
+ * EFAULT - An invalid address was specified for a parameter
+ * EINVAL - flags is invalid, or len is negative
+ * ENODEV - The remote node is lost or existed, but is not currently in the
+ * network since it may have crashed
+ * ENOMEM - Not enough space
+ * ENOTCONN - The endpoint is not connected
+ */
+int scif_recv(scif_epd_t epd, void *msg, int len, int flags);
+
+/**
+ * scif_register() - Mark a memory region for remote access.
+ * @epd:		endpoint descriptor
+ * @addr:		starting virtual address
+ * @len:		length of range
+ * @offset:		offset of window
+ * @prot_flags:		read/write protection flags
+ * @map_flags:		mapping flags
+ *
+ * The scif_register() function opens a window, a range of whole pages of the
+ * registered address space of the endpoint epd, starting at offset po and
+ * continuing for len bytes. The value of po, further described below, is a
+ * function of the parameters offset and len, and the value of map_flags. Each
+ * page of the window represents the physical memory page which backs the
+ * corresponding page of the range of virtual address pages starting at addr
+ * and continuing for len bytes. addr and len are constrained to be multiples
+ * of the page size. A successful scif_register() call returns po.
+ *
+ * When SCIF_MAP_FIXED is set in the map_flags argument, po will be offset
+ * exactly, and offset is constrained to be a multiple of the page size. The
+ * mapping established by scif_register() will not replace any existing
+ * registration; an error is returned if any page within the range [offset,
+ * offset + len - 1] intersects an existing window.
+ *
+ * When SCIF_MAP_FIXED is not set, the implementation uses offset in an
+ * implementation-defined manner to arrive at po. The po value so chosen will
+ * be an area of the registered address space that the implementation deems
+ * suitable for a mapping of len bytes. An offset value of 0 is interpreted as
+ * granting the implementation complete freedom in selecting po, subject to
+ * constraints described below. A non-zero value of offset is taken to be a
+ * suggestion of an offset near which the mapping should be placed. When the
+ * implementation selects a value for po, it does not replace any extant
+ * window. In all cases, po will be a multiple of the page size.
+ *
+ * The physical pages which are so represented by a window are available for
+ * access in calls to mmap(), scif_readfrom(), scif_writeto(),
+ * scif_vreadfrom(), and scif_vwriteto(). While a window is registered, the
+ * physical pages represented by the window will not be reused by the memory
+ * subsystem for any other purpose. Note that the same physical page may be
+ * represented by multiple windows.
+ *
+ * Subsequent operations which change the memory pages to which virtual
+ * addresses are mapped (such as mmap(), munmap()) have no effect on
+ * existing window.
+ *
+ * If the process will fork(), it is recommended that the registered
+ * virtual address range be marked with MADV_DONTFORK. Doing so will prevent
+ * problems due to copy-on-write semantics.
+ *
+ * The prot_flags argument is formed by OR'ing together one or more of the
+ * following values.
+ * SCIF_PROT_READ - allow read operations from the window
+ * SCIF_PROT_WRITE - allow write operations to the window
+ *
+ * The map_flags argument can be set to SCIF_MAP_FIXED which interprets a
+ * fixed offset.
+ *
+ * Return:
+ * Upon successful completion, scif_register() returns the offset at which the
+ * mapping was placed (po); otherwise in user mode SCIF_REGISTER_FAILED (that
+ * is (off_t *)-1) is returned and errno is set to indicate the error; in
+ * kernel mode the negative of one of the following errors is returned.
+ *
+ * Errors:
+ * EADDRINUSE - SCIF_MAP_FIXED is set in map_flags, and pages in the range
+ * [offset, offset + len -1] are already registered
+ * EAGAIN - The mapping could not be performed due to lack of resources
+ * EBADF, ENOTTY - epd is not a valid endpoint descriptor
+ * ECONNRESET - Connection reset by peer
+ * EFAULT - Addresses in the range [addr, addr + len - 1] are invalid
+ * EINVAL - map_flags is invalid, or prot_flags is invalid, or SCIF_MAP_FIXED is
+ * set in flags, and offset is not a multiple of the page size, or addr is not a
+ * multiple of the page size, or len is not a multiple of the page size, or is
+ * 0, or offset is negative
+ * ENODEV - The remote node is lost or existed, but is not currently in the
+ * network since it may have crashed
+ * ENOMEM - Not enough space
+ * ENOTCONN -The endpoint is not connected
+ */
+off_t scif_register(scif_epd_t epd, void *addr, size_t len, off_t offset,
+		    int prot_flags, int map_flags);
+
+/**
+ * scif_unregister() - Mark a memory region for remote access.
+ * @epd:	endpoint descriptor
+ * @offset:	start of range to unregister
+ * @len:	length of range to unregister
+ *
+ * The scif_unregister() function closes those previously registered windows
+ * which are entirely within the range [offset, offset + len - 1]. It is an
+ * error to specify a range which intersects only a subrange of a window.
+ *
+ * On a successful return, pages within the window may no longer be specified
+ * in calls to mmap(), scif_readfrom(), scif_writeto(), scif_vreadfrom(),
+ * scif_vwriteto(), scif_get_pages, and scif_fence_signal(). The window,
+ * however, continues to exist until all previous references against it are
+ * removed. A window is referenced if there is a mapping to it created by
+ * mmap(), or if scif_get_pages() was called against the window
+ * (and the pages have not been returned via scif_put_pages()). A window is
+ * also referenced while an RMA, in which some range of the window is a source
+ * or destination, is in progress. Finally a window is referenced while some
+ * offset in that window was specified to scif_fence_signal(), and the RMAs
+ * marked by that call to scif_fence_signal() have not completed. While a
+ * window is in this state, its registered address space pages are not
+ * available for use in a new registered window.
+ *
+ * When all such references to the window have been removed, its references to
+ * all the physical pages which it represents are removed. Similarly, the
+ * registered address space pages of the window become available for
+ * registration in a new window.
+ *
+ * Return:
+ * Upon successful completion, scif_unregister() returns 0; otherwise in user
+ * mode -1 is returned and errno is set to indicate the error; in kernel mode
+ * the negative of one of the following errors is returned. In the event of an
+ * error, no windows are unregistered.
+ *
+ * Errors:
+ * EBADF, ENOTTY - epd is not a valid endpoint descriptor
+ * ECONNRESET - Connection reset by peer
+ * EINVAL - the range [offset, offset + len - 1] intersects a subrange of a
+ * window, or offset is negative
+ * ENODEV - The remote node is lost or existed, but is not currently in the
+ * network since it may have crashed
+ * ENOTCONN - The endpoint is not connected
+ * ENXIO - Offsets in the range [offset, offset + len - 1] are invalid for the
+ * registered address space of epd
+ */
+int scif_unregister(scif_epd_t epd, off_t offset, size_t len);
+
+/**
+ * scif_readfrom() - Copy from a remote address space
+ * @epd:	endpoint descriptor
+ * @loffset:	offset in local registered address space to
+ *		which to copy
+ * @len:	length of range to copy
+ * @roffset:	offset in remote registered address space
+ *		from which to copy
+ * @rma_flags:	transfer mode flags
+ *
+ * scif_readfrom() copies len bytes from the remote registered address space of
+ * the peer of endpoint epd, starting at the offset roffset to the local
+ * registered address space of epd, starting at the offset loffset.
+ *
+ * Each of the specified ranges [loffset, loffset + len - 1] and [roffset,
+ * roffset + len - 1] must be within some registered window or windows of the
+ * local and remote nodes. A range may intersect multiple registered windows,
+ * but only if those windows are contiguous in the registered address space.
+ *
+ * If rma_flags includes SCIF_RMA_USECPU, then the data is copied using
+ * programmed read/writes. Otherwise the data is copied using DMA. If rma_-
+ * flags includes SCIF_RMA_SYNC, then scif_readfrom() will return after the
+ * transfer is complete. Otherwise, the transfer may be performed asynchron-
+ * ously. The order in which any two asynchronous RMA operations complete
+ * is non-deterministic. The synchronization functions, scif_fence_mark()/
+ * scif_fence_wait() and scif_fence_signal(), can be used to synchronize to
+ * the completion of asynchronous RMA operations on the same endpoint.
+ *
+ * The DMA transfer of individual bytes is not guaranteed to complete in
+ * address order. If rma_flags includes SCIF_RMA_ORDERED, then the last
+ * cacheline or partial cacheline of the source range will become visible on
+ * the destination node after all other transferred data in the source
+ * range has become visible on the destination node.
+ *
+ * The optimal DMA performance will likely be realized if both
+ * loffset and roffset are cacheline aligned (are a multiple of 64). Lower
+ * performance will likely be realized if loffset and roffset are not
+ * cacheline aligned but are separated by some multiple of 64. The lowest level
+ * of performance is likely if loffset and roffset are not separated by a
+ * multiple of 64.
+ *
+ * The rma_flags argument is formed by ORing together zero or more of the
+ * following values.
+ * SCIF_RMA_USECPU - perform the transfer using the CPU, otherwise use the DMA
+ *	engine.
+ * SCIF_RMA_SYNC - perform the transfer synchronously, returning after the
+ *		transfer has completed. Passing this flag results in the
+ *		current implementation busy waiting and consuming CPU cycles
+ *		while the DMA transfer is in progress for best performance by
+ *		avoiding the interrupt latency.
+ * SCIF_RMA_ORDERED - ensure that the last cacheline or partial cacheline of
+ *		the source range becomes visible on the destination node
+ *		after all other transferred data in the source range has
+ *		become visible on the destination
+ *
+ * Return:
+ * Upon successful completion, scif_readfrom() returns 0; otherwise in user
+ * mode -1 is returned and errno is set to indicate the error; in kernel mode
+ * the negative of one of the following errors is returned.
+ *
+ * Errors:
+ * EACCESS - Attempt to write to a read-only range
+ * EBADF, ENOTTY - epd is not a valid endpoint descriptor
+ * ECONNRESET - Connection reset by peer
+ * EINVAL - rma_flags is invalid
+ * ENODEV - The remote node is lost or existed, but is not currently in the
+ * network since it may have crashed
+ * ENOTCONN - The endpoint is not connected
+ * ENXIO - The range [loffset, loffset + len - 1] is invalid for the registered
+ * address space of epd, or, The range [roffset, roffset + len - 1] is invalid
+ * for the registered address space of the peer of epd, or loffset or roffset
+ * is negative
+ */
+int scif_readfrom(scif_epd_t epd, off_t loffset, size_t len, off_t
+		  roffset, int rma_flags);
+
+/**
+ * scif_writeto() - Copy to a remote address space
+ * @epd:	endpoint descriptor
+ * @loffset:	offset in local registered address space
+ *		from which to copy
+ * @len:	length of range to copy
+ * @roffset:	offset in remote registered address space to
+ *		which to copy
+ * @rma_flags:	transfer mode flags
+ *
+ * scif_writeto() copies len bytes from the local registered address space of
+ * epd, starting at the offset loffset to the remote registered address space
+ * of the peer of endpoint epd, starting at the offset roffset.
+ *
+ * Each of the specified ranges [loffset, loffset + len - 1] and [roffset,
+ * roffset + len - 1] must be within some registered window or windows of the
+ * local and remote nodes. A range may intersect multiple registered windows,
+ * but only if those windows are contiguous in the registered address space.
+ *
+ * If rma_flags includes SCIF_RMA_USECPU, then the data is copied using
+ * programmed read/writes. Otherwise the data is copied using DMA. If rma_-
+ * flags includes SCIF_RMA_SYNC, then scif_writeto() will return after the
+ * transfer is complete. Otherwise, the transfer may be performed asynchron-
+ * ously. The order in which any two asynchronous RMA operations complete
+ * is non-deterministic. The synchronization functions, scif_fence_mark()/
+ * scif_fence_wait() and scif_fence_signal(), can be used to synchronize to
+ * the completion of asynchronous RMA operations on the same endpoint.
+ *
+ * The DMA transfer of individual bytes is not guaranteed to complete in
+ * address order. If rma_flags includes SCIF_RMA_ORDERED, then the last
+ * cacheline or partial cacheline of the source range will become visible on
+ * the destination node after all other transferred data in the source
+ * range has become visible on the destination node.
+ *
+ * The optimal DMA performance will likely be realized if both
+ * loffset and roffset are cacheline aligned (are a multiple of 64). Lower
+ * performance will likely be realized if loffset and roffset are not cacheline
+ * aligned but are separated by some multiple of 64. The lowest level of
+ * performance is likely if loffset and roffset are not separated by a multiple
+ * of 64.
+ *
+ * The rma_flags argument is formed by ORing together zero or more of the
+ * following values.
+ * SCIF_RMA_USECPU - perform the transfer using the CPU, otherwise use the DMA
+ *			engine.
+ * SCIF_RMA_SYNC - perform the transfer synchronously, returning after the
+ *		transfer has completed. Passing this flag results in the
+ *		current implementation busy waiting and consuming CPU cycles
+ *		while the DMA transfer is in progress for best performance by
+ *		avoiding the interrupt latency.
+ * SCIF_RMA_ORDERED - ensure that the last cacheline or partial cacheline of
+ *		the source range becomes visible on the destination node
+ *		after all other transferred data in the source range has
+ *		become visible on the destination
+ *
+ * Return:
+ * Upon successful completion, scif_readfrom() returns 0; otherwise in user
+ * mode -1 is returned and errno is set to indicate the error; in kernel mode
+ * the negative of one of the following errors is returned.
+ *
+ * Errors:
+ * EACCESS - Attempt to write to a read-only range
+ * EBADF, ENOTTY - epd is not a valid endpoint descriptor
+ * ECONNRESET - Connection reset by peer
+ * EINVAL - rma_flags is invalid
+ * ENODEV - The remote node is lost or existed, but is not currently in the
+ * network since it may have crashed
+ * ENOTCONN - The endpoint is not connected
+ * ENXIO - The range [loffset, loffset + len - 1] is invalid for the registered
+ * address space of epd, or, The range [roffset , roffset + len -1] is invalid
+ * for the registered address space of the peer of epd, or loffset or roffset
+ * is negative
+ */
+int scif_writeto(scif_epd_t epd, off_t loffset, size_t len, off_t
+		 roffset, int rma_flags);
+
+/**
+ * scif_vreadfrom() - Copy from a remote address space
+ * @epd:	endpoint descriptor
+ * @addr:	address to which to copy
+ * @len:	length of range to copy
+ * @roffset:	offset in remote registered address space
+ *		from which to copy
+ * @rma_flags:	transfer mode flags
+ *
+ * scif_vreadfrom() copies len bytes from the remote registered address
+ * space of the peer of endpoint epd, starting at the offset roffset, to local
+ * memory, starting at addr.
+ *
+ * The specified range [roffset, roffset + len - 1] must be within some
+ * registered window or windows of the remote nodes. The range may
+ * intersect multiple registered windows, but only if those windows are
+ * contiguous in the registered address space.
+ *
+ * If rma_flags includes SCIF_RMA_USECPU, then the data is copied using
+ * programmed read/writes. Otherwise the data is copied using DMA. If rma_-
+ * flags includes SCIF_RMA_SYNC, then scif_vreadfrom() will return after the
+ * transfer is complete. Otherwise, the transfer may be performed asynchron-
+ * ously. The order in which any two asynchronous RMA operations complete
+ * is non-deterministic. The synchronization functions, scif_fence_mark()/
+ * scif_fence_wait() and scif_fence_signal(), can be used to synchronize to
+ * the completion of asynchronous RMA operations on the same endpoint.
+ *
+ * The DMA transfer of individual bytes is not guaranteed to complete in
+ * address order. If rma_flags includes SCIF_RMA_ORDERED, then the last
+ * cacheline or partial cacheline of the source range will become visible on
+ * the destination node after all other transferred data in the source
+ * range has become visible on the destination node.
+ *
+ * If rma_flags includes SCIF_RMA_USECACHE, then the physical pages which back
+ * the specified local memory range may be remain in a pinned state even after
+ * the specified transfer completes. This may reduce overhead if some or all of
+ * the same virtual address range is referenced in a subsequent call of
+ * scif_vreadfrom() or scif_vwriteto().
+ *
+ * The optimal DMA performance will likely be realized if both
+ * addr and roffset are cacheline aligned (are a multiple of 64). Lower
+ * performance will likely be realized if addr and roffset are not
+ * cacheline aligned but are separated by some multiple of 64. The lowest level
+ * of performance is likely if addr and roffset are not separated by a
+ * multiple of 64.
+ *
+ * The rma_flags argument is formed by ORing together zero or more of the
+ * following values.
+ * SCIF_RMA_USECPU - perform the transfer using the CPU, otherwise use the DMA
+ *	engine.
+ * SCIF_RMA_USECACHE - enable registration caching
+ * SCIF_RMA_SYNC - perform the transfer synchronously, returning after the
+ *		transfer has completed. Passing this flag results in the
+ *		current implementation busy waiting and consuming CPU cycles
+ *		while the DMA transfer is in progress for best performance by
+ *		avoiding the interrupt latency.
+ * SCIF_RMA_ORDERED - ensure that the last cacheline or partial cacheline of
+ *	the source range becomes visible on the destination node
+ *	after all other transferred data in the source range has
+ *	become visible on the destination
+ *
+ * Return:
+ * Upon successful completion, scif_vreadfrom() returns 0; otherwise in user
+ * mode -1 is returned and errno is set to indicate the error; in kernel mode
+ * the negative of one of the following errors is returned.
+ *
+ * Errors:
+ * EACCESS - Attempt to write to a read-only range
+ * EBADF, ENOTTY - epd is not a valid endpoint descriptor
+ * ECONNRESET - Connection reset by peer
+ * EFAULT - Addresses in the range [addr, addr + len - 1] are invalid
+ * EINVAL - rma_flags is invalid
+ * ENODEV - The remote node is lost or existed, but is not currently in the
+ * network since it may have crashed
+ * ENOTCONN - The endpoint is not connected
+ * ENXIO - Offsets in the range [roffset, roffset + len - 1] are invalid for the
+ * registered address space of epd
+ */
+int scif_vreadfrom(scif_epd_t epd, void *addr, size_t len, off_t roffset,
+		   int rma_flags);
+
+/**
+ * scif_vwriteto() - Copy to a remote address space
+ * @epd:	endpoint descriptor
+ * @addr:	address from which to copy
+ * @len:	length of range to copy
+ * @roffset:	offset in remote registered address space to
+ *		which to copy
+ * @rma_flags:	transfer mode flags
+ *
+ * scif_vwriteto() copies len bytes from the local memory, starting at addr, to
+ * the remote registered address space of the peer of endpoint epd, starting at
+ * the offset roffset.
+ *
+ * The specified range [roffset, roffset + len - 1] must be within some
+ * registered window or windows of the remote nodes. The range may intersect
+ * multiple registered windows, but only if those windows are contiguous in the
+ * registered address space.
+ *
+ * If rma_flags includes SCIF_RMA_USECPU, then the data is copied using
+ * programmed read/writes. Otherwise the data is copied using DMA. If rma_-
+ * flags includes SCIF_RMA_SYNC, then scif_vwriteto() will return after the
+ * transfer is complete. Otherwise, the transfer may be performed asynchron-
+ * ously. The order in which any two asynchronous RMA operations complete
+ * is non-deterministic. The synchronization functions, scif_fence_mark()/
+ * scif_fence_wait() and scif_fence_signal(), can be used to synchronize to
+ * the completion of asynchronous RMA operations on the same endpoint.
+ *
+ * The DMA transfer of individual bytes is not guaranteed to complete in
+ * address order. If rma_flags includes SCIF_RMA_ORDERED, then the last
+ * cacheline or partial cacheline of the source range will become visible on
+ * the destination node after all other transferred data in the source
+ * range has become visible on the destination node.
+ *
+ * If rma_flags includes SCIF_RMA_USECACHE, then the physical pages which back
+ * the specified local memory range may be remain in a pinned state even after
+ * the specified transfer completes. This may reduce overhead if some or all of
+ * the same virtual address range is referenced in a subsequent call of
+ * scif_vreadfrom() or scif_vwriteto().
+ *
+ * The optimal DMA performance will likely be realized if both
+ * addr and offset are cacheline aligned (are a multiple of 64). Lower
+ * performance will likely be realized if addr and offset are not cacheline
+ * aligned but are separated by some multiple of 64. The lowest level of
+ * performance is likely if addr and offset are not separated by a multiple of
+ * 64.
+ *
+ * The rma_flags argument is formed by ORing together zero or more of the
+ * following values.
+ * SCIF_RMA_USECPU - perform the transfer using the CPU, otherwise use the DMA
+ *	engine.
+ * SCIF_RMA_USECACHE - allow registration caching
+ * SCIF_RMA_SYNC - perform the transfer synchronously, returning after the
+ *		transfer has completed. Passing this flag results in the
+ *		current implementation busy waiting and consuming CPU cycles
+ *		while the DMA transfer is in progress for best performance by
+ *		avoiding the interrupt latency.
+ * SCIF_RMA_ORDERED - ensure that the last cacheline or partial cacheline of
+ *		the source range becomes visible on the destination node
+ *		after all other transferred data in the source range has
+ *		become visible on the destination
+ *
+ * Return:
+ * Upon successful completion, scif_vwriteto() returns 0; otherwise in user
+ * mode -1 is returned and errno is set to indicate the error; in kernel mode
+ * the negative of one of the following errors is returned.
+ *
+ * Errors:
+ * EACCESS - Attempt to write to a read-only range
+ * EBADF, ENOTTY - epd is not a valid endpoint descriptor
+ * ECONNRESET - Connection reset by peer
+ * EFAULT - Addresses in the range [addr, addr + len - 1] are invalid
+ * EINVAL - rma_flags is invalid
+ * ENODEV - The remote node is lost or existed, but is not currently in the
+ * network since it may have crashed
+ * ENOTCONN - The endpoint is not connected
+ * ENXIO - Offsets in the range [roffset, roffset + len - 1] are invalid for the
+ * registered address space of epd
+ */
+int scif_vwriteto(scif_epd_t epd, void *addr, size_t len, off_t roffset,
+		  int rma_flags);
+
+/**
+ * scif_fence_mark() - Mark previously issued RMAs
+ * @epd:	endpoint descriptor
+ * @flags:	control flags
+ * @mark:	marked value returned as output.
+ *
+ * scif_fence_mark() returns after marking the current set of all uncompleted
+ * RMAs initiated through the endpoint epd or the current set of all
+ * uncompleted RMAs initiated through the peer of endpoint epd. The RMAs are
+ * marked with a value returned at mark. The application may subsequently call
+ * scif_fence_wait(), passing the value returned at mark, to await completion
+ * of all RMAs so marked.
+ *
+ * The flags argument has exactly one of the following values.
+ * SCIF_FENCE_INIT_SELF - RMA operations initiated through endpoint
+ *	epd are marked
+ * SCIF_FENCE_INIT_PEER - RMA operations initiated through the peer
+ *	of endpoint epd are marked
+ *
+ * Return:
+ * Upon successful completion, scif_fence_mark() returns 0; otherwise in user
+ * mode -1 is returned and errno is set to indicate the error; in kernel mode
+ * the negative of one of the following errors is returned.
+ *
+ * Errors:
+ * EBADF, ENOTTY - epd is not a valid endpoint descriptor
+ * ECONNRESET - Connection reset by peer
+ * EINVAL - flags is invalid
+ * ENODEV - The remote node is lost or existed, but is not currently in the
+ * network since it may have crashed
+ * ENOTCONN - The endpoint is not connected
+ * ENOMEM - Insufficient kernel memory was available
+ */
+int scif_fence_mark(scif_epd_t epd, int flags, int *mark);
+
+/**
+ * scif_fence_wait() - Wait for completion of marked RMAs
+ * @epd:	endpoint descriptor
+ * @mark:	mark request
+ *
+ * scif_fence_wait() returns after all RMAs marked with mark have completed.
+ * The value passed in mark must have been obtained in a previous call to
+ * scif_fence_mark().
+ *
+ * Return:
+ * Upon successful completion, scif_fence_wait() returns 0; otherwise in user
+ * mode -1 is returned and errno is set to indicate the error; in kernel mode
+ * the negative of one of the following errors is returned.
+ *
+ * Errors:
+ * EBADF, ENOTTY - epd is not a valid endpoint descriptor
+ * ECONNRESET - Connection reset by peer
+ * ENODEV - The remote node is lost or existed, but is not currently in the
+ * network since it may have crashed
+ * ENOTCONN - The endpoint is not connected
+ * ENOMEM - Insufficient kernel memory was available
+ */
+int scif_fence_wait(scif_epd_t epd, int mark);
+
+/**
+ * scif_fence_signal() - Request a memory update on completion of RMAs
+ * @epd:	endpoint descriptor
+ * @loff:	local offset
+ * @lval:	local value to write to loffset
+ * @roff:	remote offset
+ * @rval:	remote value to write to roffset
+ * @flags:	flags
+ *
+ * scif_fence_signal() returns after marking the current set of all uncompleted
+ * RMAs initiated through the endpoint epd or marking the current set of all
+ * uncompleted RMAs initiated through the peer of endpoint epd.
+ *
+ * If flags includes SCIF_SIGNAL_LOCAL, then on completion of the RMAs in the
+ * marked set, lval is written to memory at the address corresponding to offset
+ * loff in the local registered address space of epd. loff must be within a
+ * registered window. If flags includes SCIF_SIGNAL_REMOTE, then on completion
+ * of the RMAs in the marked set, rval is written to memory at the address
+ * corresponding to offset roff in the remote registered address space of epd.
+ * roff must be within a remote registered window of the peer of epd. Note
+ * that any specified offset must be DWORD (4 byte / 32 bit) aligned.
+ *
+ * The flags argument is formed by OR'ing together the following.
+ * Exactly one of the following values.
+ * SCIF_FENCE_INIT_SELF - RMA operations initiated through endpoint
+ *	epd are marked
+ * SCIF_FENCE_INIT_PEER - RMA operations initiated through the peer
+ *	of endpoint epd are marked
+ * One or more of the following values.
+ * SCIF_SIGNAL_LOCAL - On completion of the marked set of RMAs, write lval to
+ *	memory at the address corresponding to offset loff in the local
+ *	registered address space of epd.
+ * SCIF_SIGNAL_REMOTE - On completion of the marked set of RMAs, write rval to
+ *	memory at the address corresponding to offset roff in the remote
+ *	registered address space of epd.
+ *
+ * Return:
+ * Upon successful completion, scif_fence_signal() returns 0; otherwise in
+ * user mode -1 is returned and errno is set to indicate the error; in kernel
+ * mode the negative of one of the following errors is returned.
+ *
+ * Errors:
+ * EBADF, ENOTTY - epd is not a valid endpoint descriptor
+ * ECONNRESET - Connection reset by peer
+ * EINVAL - flags is invalid, or loff or roff are not DWORD aligned
+ * ENODEV - The remote node is lost or existed, but is not currently in the
+ * network since it may have crashed
+ * ENOTCONN - The endpoint is not connected
+ * ENXIO - loff is invalid for the registered address of epd, or roff is invalid
+ * for the registered address space, of the peer of epd
+ */
+int scif_fence_signal(scif_epd_t epd, off_t loff, u64 lval, off_t roff,
+		      u64 rval, int flags);
+
+/**
+ * scif_get_node_ids() - Return information about online nodes
+ * @nodes:	array in which to return online node IDs
+ * @len:	number of entries in the nodes array
+ * @self:	address to place the node ID of the local node
+ *
+ * scif_get_node_ids() fills in the nodes array with up to len node IDs of the
+ * nodes in the SCIF network. If there is not enough space in nodes, as
+ * indicated by the len parameter, only len node IDs are returned in nodes. The
+ * return value of scif_get_node_ids() is the total number of nodes currently in
+ * the SCIF network. By checking the return value against the len parameter,
+ * the user may determine if enough space for nodes was allocated.
+ *
+ * The node ID of the local node is returned at self.
+ *
+ * Return:
+ * Upon successful completion, scif_get_node_ids() returns the actual number of
+ * online nodes in the SCIF network including 'self'; otherwise in user mode
+ * -1 is returned and errno is set to indicate the error; in kernel mode no
+ * errors are returned.
+ *
+ * Errors:
+ * EFAULT - Bad address
+ */
+int scif_get_node_ids(u16 *nodes, int len, u16 *self);
+
+#endif /* __SCIF_H__ */