[fcp] Add support for the Fibre Channel Protocol

The Fibre Channel Protocol provides a mechanism for transporting SCSI
commands via a Fibre Channel fabric.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

1 files changed, 1005 insertions, 0 deletions

diff --git a/src/net/fcp.c b/src/net/fcp.c
new file mode 100644
index 00000000..42f6528e
--- /dev/null
+++ b/src/net/fcp.c
@@ -0,0 +1,1005 @@
+/*
+ * Copyright (C) 2010 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <stddef.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <stdio.h>
+#include <assert.h>
+#include <byteswap.h>
+#include <ipxe/refcnt.h>
+#include <ipxe/list.h>
+#include <ipxe/interface.h>
+#include <ipxe/xfer.h>
+#include <ipxe/iobuf.h>
+#include <ipxe/open.h>
+#include <ipxe/process.h>
+#include <ipxe/uri.h>
+#include <ipxe/acpi.h>
+#include <ipxe/scsi.h>
+#include <ipxe/fc.h>
+#include <ipxe/fcels.h>
+#include <ipxe/fcp.h>
+
+/** @file
+ *
+ * Fibre Channel Protocol
+ *
+ */
+
+/* Disambiguate the various error causes */
+#define ERANGE_READ_DATA_ORDERING \
+	__einfo_error ( EINFO_ERANGE_READ_DATA_ORDERING )
+#define EINFO_ERANGE_READ_DATA_ORDERING \
+	__einfo_uniqify ( EINFO_ERANGE, 0x01, "Read data out of order" )
+#define ERANGE_READ_DATA_OVERRUN \
+	__einfo_error ( EINFO_ERANGE_READ_DATA_OVERRUN )
+#define EINFO_ERANGE_READ_DATA_OVERRUN \
+	__einfo_uniqify ( EINFO_ERANGE, 0x02, "Read data overrun" )
+#define ERANGE_WRITE_DATA_STUCK \
+	__einfo_error ( EINFO_ERANGE_WRITE_DATA_STUCK )
+#define EINFO_ERANGE_WRITE_DATA_STUCK \
+	__einfo_uniqify ( EINFO_ERANGE, 0x03, "Write data stuck" )
+#define ERANGE_WRITE_DATA_OVERRUN \
+	__einfo_error ( EINFO_ERANGE_WRITE_DATA_OVERRUN )
+#define EINFO_ERANGE_WRITE_DATA_OVERRUN \
+	__einfo_uniqify ( EINFO_ERANGE, 0x04, "Write data overrun" )
+#define ERANGE_DATA_UNDERRUN \
+	__einfo_error ( EINFO_ERANGE_DATA_UNDERRUN )
+#define EINFO_ERANGE_DATA_UNDERRUN \
+	__einfo_uniqify ( EINFO_ERANGE, 0x05, "Data underrun" )
+
+/******************************************************************************
+ *
+ * PRLI
+ *
+ ******************************************************************************
+ */
+
+struct fc_els_prli_descriptor fcp_prli_descriptor __fc_els_prli_descriptor;
+
+/**
+ * Transmit FCP PRLI
+ *
+ * @v els		Fibre Channel ELS transaction
+ * @ret rc		Return status code
+ */
+static int fcp_prli_tx ( struct fc_els *els ) {
+	struct fcp_prli_service_parameters param;
+
+	/* Build service parameter page */
+	memset ( &param, 0, sizeof ( param ) );
+	param.flags = htonl ( FCP_PRLI_NO_READ_RDY | FCP_PRLI_INITIATOR );
+
+	return fc_els_prli_tx ( els, &fcp_prli_descriptor, &param );
+}
+
+/**
+ * Receive FCP PRLI
+ *
+ * @v els		Fibre Channel ELS transaction
+ * @v frame		ELS frame
+ * @v len		Length of ELS frame
+ * @ret rc		Return status code
+ */
+static int fcp_prli_rx ( struct fc_els *els, const void *data, size_t len ) {
+	return fc_els_prli_rx ( els, &fcp_prli_descriptor, data, len );
+}
+
+/**
+ * Detect FCP PRLI
+ *
+ * @v els		Fibre Channel ELS transaction
+ * @v data		ELS frame
+ * @v len		Length of ELS frame
+ * @ret rc		Return status code
+ */
+static int fcp_prli_detect ( struct fc_els *els, const void *data,
+			     size_t len ) {
+	return fc_els_prli_detect ( els, &fcp_prli_descriptor, data, len );
+}
+
+/** FCP PRLI ELS handler */
+struct fc_els_handler fcp_prli_handler __fc_els_handler = {
+	.name		= "PRLI-FCP",
+	.tx_request	= fcp_prli_tx,
+	.tx_response	= fcp_prli_tx,
+	.rx_request	= fcp_prli_rx,
+	.rx_response	= fcp_prli_rx,
+	.detect		= fcp_prli_detect,
+};
+
+/** FCP PRLI descriptor */
+struct fc_els_prli_descriptor fcp_prli_descriptor __fc_els_prli_descriptor = {
+	.type		= FC_TYPE_FCP,
+	.param_len	= sizeof ( struct fcp_prli_service_parameters ),
+	.handler	= &fcp_prli_handler,
+};
+
+/******************************************************************************
+ *
+ * FCP devices and commands
+ *
+ ******************************************************************************
+ */
+
+/** An FCP device */
+struct fcp_device {
+	/** Reference count */
+	struct refcnt refcnt;
+	/** Fibre Channel upper-layer protocol */
+	struct fc_ulp *ulp;
+	/** SCSI command issuing interface */
+	struct interface scsi;
+	/** List of active commands */
+	struct list_head fcpcmds;
+};
+
+/** An FCP command */
+struct fcp_command {
+	/** Reference count */
+	struct refcnt refcnt;
+	/** FCP SCSI device */
+	struct fcp_device *fcpdev;
+	/** List of active commands */
+	struct list_head list;
+	/** SCSI command interface */
+	struct interface scsi;
+	/** Fibre Channel exchange interface */
+	struct interface xchg;
+	/** Send process */
+	struct process process;
+	/** Send current IU
+	 *
+	 * @v fcpcmd	FCP command
+	 * @ret rc	Return status code
+	 */
+	int ( * send ) ( struct fcp_command *fcpcmd );
+	/** SCSI command */
+	struct scsi_cmd command;
+	/** Data offset within command */
+	size_t offset;
+	/** Length of data remaining to be sent within this IU */
+	size_t remaining;
+	/** Command reference */
+	uint8_t ref;
+};
+
+/**
+ * Get reference to FCP device
+ *
+ * @v fcpdev		FCP device
+ * @ret fcpdev		FCP device
+ */
+static inline __attribute__ (( always_inline )) struct fcp_device *
+fcpdev_get ( struct fcp_device *fcpdev ) {
+	ref_get ( &fcpdev->refcnt );
+	return fcpdev;
+}
+
+/**
+ * Drop reference to FCP device
+ *
+ * @v fcpdev		FCP device
+ */
+static inline __attribute__ (( always_inline )) void
+fcpdev_put ( struct fcp_device *fcpdev ) {
+	ref_put ( &fcpdev->refcnt );
+}
+
+/**
+ * Get reference to FCP command
+ *
+ * @v fcpcmd		FCP command
+ * @ret fcpcmd		FCP command
+ */
+static inline __attribute__ (( always_inline )) struct fcp_command *
+fcpcmd_get ( struct fcp_command *fcpcmd ) {
+	ref_get ( &fcpcmd->refcnt );
+	return fcpcmd;
+}
+
+/**
+ * Drop reference to FCP command
+ *
+ * @v fcpcmd		FCP command
+ */
+static inline __attribute__ (( always_inline )) void
+fcpcmd_put ( struct fcp_command *fcpcmd ) {
+	ref_put ( &fcpcmd->refcnt );
+}
+
+/**
+ * Start FCP command sending
+ *
+ * @v fcpcmd		FCP command
+ * @v send		Send method
+ */
+static inline __attribute__ (( always_inline )) void
+fcpcmd_start_send ( struct fcp_command *fcpcmd,
+		    int ( * send ) ( struct fcp_command *fcpcmd ) ) {
+	fcpcmd->send = send;
+	process_add ( &fcpcmd->process );
+}
+
+/**
+ * Stop FCP command sending
+ *
+ * @v fcpcmd		FCP command
+ */
+static inline __attribute__ (( always_inline )) void
+fcpcmd_stop_send ( struct fcp_command *fcpcmd ) {
+	process_del ( &fcpcmd->process );
+}
+
+/**
+ * Free FCP command
+ *
+ * @v refcnt		Reference count
+ */
+static void fcpcmd_free ( struct refcnt *refcnt ) {
+	struct fcp_command *fcpcmd =
+		container_of ( refcnt, struct fcp_command, refcnt );
+
+	/* Remove from list of commands */
+	list_del ( &fcpcmd->list );
+	fcpdev_put ( fcpcmd->fcpdev );
+
+	/* Free command */
+	free ( fcpcmd );
+}
+
+/**
+ * Close FCP command
+ *
+ * @v fcpcmd		FCP command
+ * @v rc		Reason for close
+ */
+static void fcpcmd_close ( struct fcp_command *fcpcmd, int rc ) {
+	struct fcp_device *fcpdev = fcpcmd->fcpdev;
+
+	if ( rc != 0 ) {
+		DBGC ( fcpdev, "FCP %p ref %02x closed: %s\n",
+		       fcpdev, fcpcmd->ref, strerror ( rc ) );
+	}
+
+	/* Stop sending */
+	fcpcmd_stop_send ( fcpcmd );
+
+	/* Shut down interfaces */
+	intf_shutdown ( &fcpcmd->scsi, rc );
+	intf_shutdown ( &fcpcmd->xchg, rc );
+}
+
+/**
+ * Close FCP command in error
+ *
+ * @v fcpcmd		FCP command
+ * @v rc		Reason for close
+ */
+static void fcpcmd_close_err ( struct fcp_command *fcpcmd, int rc ) {
+	if ( rc == 0 )
+		rc = -EPIPE;
+	fcpcmd_close ( fcpcmd, rc );
+}
+
+/**
+ * Send FCP command IU
+ *
+ * @v fcpcmd		FCP command
+ * @ret rc		Return status code
+ */
+static int fcpcmd_send_cmnd ( struct fcp_command *fcpcmd ) {
+	struct fcp_device *fcpdev = fcpcmd->fcpdev;
+	struct scsi_cmd *command = &fcpcmd->command;
+	struct io_buffer *iobuf;
+	struct fcp_cmnd *cmnd;
+	struct xfer_metadata meta;
+	int rc;
+
+	/* Sanity check */
+	if ( command->data_in_len && command->data_out_len ) {
+		DBGC ( fcpdev, "FCP %p ref %02x cannot handle bidirectional "
+		       "command\n", fcpdev, fcpcmd->ref );
+		return -ENOTSUP;
+	}
+
+	/* Allocate I/O buffer */
+	iobuf = xfer_alloc_iob ( &fcpcmd->xchg, sizeof ( *cmnd ) );
+	if ( ! iobuf ) {
+		DBGC ( fcpdev, "FCP %p ref %02x cannot allocate command IU\n",
+		       fcpdev, fcpcmd->ref );
+		return -ENOMEM;
+	}
+
+	/* Construct command IU frame */
+	cmnd = iob_put ( iobuf, sizeof ( *cmnd ) );
+	memset ( cmnd, 0, sizeof ( *cmnd ) );
+	memcpy ( &cmnd->lun, &command->lun, sizeof ( cmnd->lun ) );
+	cmnd->ref = fcpcmd->ref;
+	assert ( ! ( command->data_in_len && command->data_out_len ) );
+	if ( command->data_in_len )
+		cmnd->dirn |= FCP_CMND_RDDATA;
+	if ( command->data_out_len )
+		cmnd->dirn |= FCP_CMND_WRDATA;
+	memcpy ( &cmnd->cdb, &fcpcmd->command.cdb, sizeof ( cmnd->cdb ) );
+	cmnd->len = htonl ( command->data_in_len + command->data_out_len );
+	memset ( &meta, 0, sizeof ( meta ) );
+	meta.flags = ( XFER_FL_CMD_STAT | XFER_FL_OVER );
+	DBGC2 ( fcpdev, "FCP %p ref %02x CMND " SCSI_CDB_FORMAT " %04x\n",
+		fcpdev, fcpcmd->ref, SCSI_CDB_DATA ( cmnd->cdb ),
+		ntohl ( cmnd->len ) );
+
+	/* No further data to send within this IU */
+	fcpcmd_stop_send ( fcpcmd );
+
+	/* Send command IU frame */
+	if ( ( rc = xfer_deliver ( &fcpcmd->xchg, iob_disown ( iobuf ),
+				   &meta ) ) != 0 ) {
+		DBGC ( fcpdev, "FCP %p ref %02x cannot deliver command IU: "
+		       "%s\n", fcpdev, fcpcmd->ref, strerror ( rc ) );
+		return rc;
+	}
+
+	return 0;
+}
+
+/**
+ * Handle FCP read data IU
+ *
+ * @v fcpcmd		FCP command
+ * @v iobuf		I/O buffer
+ * @v meta		Data transfer metadata
+ * @ret rc		Return status code
+ */
+static int fcpcmd_recv_rddata ( struct fcp_command *fcpcmd,
+				struct io_buffer *iobuf,
+				struct xfer_metadata *meta ) {
+	struct fcp_device *fcpdev = fcpcmd->fcpdev;
+	struct scsi_cmd *command = &fcpcmd->command;
+	size_t offset = meta->offset;
+	size_t len = iob_len ( iobuf );
+	int rc;
+
+	/* Sanity checks */
+	if ( ! ( meta->flags & XFER_FL_ABS_OFFSET ) ) {
+		DBGC ( fcpdev, "FCP %p ref %02x read data missing offset\n",
+		       fcpdev, fcpcmd->ref );
+		rc = -ERANGE_READ_DATA_ORDERING;
+		goto done;
+	}
+	if ( offset != fcpcmd->offset ) {
+		DBGC ( fcpdev, "FCP %p ref %02x read data out of order "
+		       "(expected %zd, received %zd)\n",
+		       fcpdev, fcpcmd->ref, fcpcmd->offset, offset );
+		rc = -ERANGE_READ_DATA_ORDERING;
+		goto done;
+	}
+	if ( ( offset + len ) > command->data_in_len ) {
+		DBGC ( fcpdev, "FCP %p ref %02x read data overrun (max %zd, "
+		       "received %zd)\n", fcpdev, fcpcmd->ref,
+		       command->data_in_len, ( offset + len ) );
+		rc = -ERANGE_READ_DATA_OVERRUN;
+		goto done;
+	}
+	DBGC2 ( fcpdev, "FCP %p ref %02x RDDATA [%08zx,%08zx)\n",
+		fcpdev, fcpcmd->ref, offset, ( offset + len ) );
+
+	/* Copy to user buffer */
+	copy_to_user ( command->data_in, offset, iobuf->data, len );
+	fcpcmd->offset += len;
+	assert ( fcpcmd->offset <= command->data_in_len );
+
+	rc = 0;
+ done:
+	free_iob ( iobuf );
+	return rc;
+}
+
+/**
+ * Send FCP write data IU
+ *
+ * @v fcpcmd		FCP command
+ * @ret rc		Return status code
+ */
+static int fcpcmd_send_wrdata ( struct fcp_command *fcpcmd ) {
+	struct fcp_device *fcpdev = fcpcmd->fcpdev;
+	struct scsi_cmd *command = &fcpcmd->command;
+	struct io_buffer *iobuf;
+	struct xfer_metadata meta;
+	size_t len;
+	int rc;
+
+	/* Calculate length to be sent */
+	len = xfer_window ( &fcpcmd->xchg );
+	if ( len > fcpcmd->remaining )
+		len = fcpcmd->remaining;
+
+	/* Sanity checks */
+	if ( len == 0 ) {
+		DBGC ( fcpdev, "FCP %p ref %02x write data stuck\n",
+		       fcpdev, fcpcmd->ref );
+		return -ERANGE_WRITE_DATA_STUCK;
+	}
+	if ( ( fcpcmd->offset + len ) > command->data_out_len ) {
+		DBGC ( fcpdev, "FCP %p ref %02x write data overrun (max %zd, "
+		       "requested %zd)\n", fcpdev, fcpcmd->ref,
+		       command->data_out_len, ( fcpcmd->offset + len ) );
+		return -ERANGE_WRITE_DATA_OVERRUN;
+	}
+
+	/* Allocate I/O buffer */
+	iobuf = xfer_alloc_iob ( &fcpcmd->xchg, len );
+	if ( ! iobuf ) {
+		DBGC ( fcpdev, "FCP %p ref %02x cannot allocate write data IU "
+		       "for %zd bytes\n", fcpdev, fcpcmd->ref, len );
+		return -ENOMEM;
+	}
+
+	/* Construct data IU frame */
+	copy_from_user ( iob_put ( iobuf, len ), command->data_out,
+			 fcpcmd->offset, len );
+	memset ( &meta, 0, sizeof ( meta ) );
+	meta.flags = ( XFER_FL_RESPONSE | XFER_FL_ABS_OFFSET );
+	meta.offset = fcpcmd->offset;
+	DBGC2 ( fcpdev, "FCP %p ref %02x WRDATA [%08zx,%04zx)\n",
+		fcpdev, fcpcmd->ref, fcpcmd->offset,
+		( fcpcmd->offset + iob_len ( iobuf ) ) );
+
+	/* Calculate amount of data remaining to be sent within this IU */
+	assert ( len <= fcpcmd->remaining );
+	fcpcmd->offset += len;
+	fcpcmd->remaining -= len;
+	assert ( fcpcmd->offset <= command->data_out_len );
+	if ( fcpcmd->remaining == 0 ) {
+		fcpcmd_stop_send ( fcpcmd );
+		meta.flags |= XFER_FL_OVER;
+	}
+
+	/* Send data IU frame */
+	if ( ( rc = xfer_deliver ( &fcpcmd->xchg, iob_disown ( iobuf ),
+				   &meta ) ) != 0 ) {
+		DBGC ( fcpdev, "FCP %p ref %02x cannot deliver write data IU: "
+		       "%s\n", fcpdev, fcpcmd->ref, strerror ( rc ) );
+		return rc;
+	}
+
+	return 0;
+}
+
+/**
+ * Handle FCP transfer ready IU
+ *
+ * @v fcpcmd		FCP command
+ * @v iobuf		I/O buffer
+ * @v meta		Data transfer metadata
+ * @ret rc		Return status code
+ */
+static int fcpcmd_recv_xfer_rdy ( struct fcp_command *fcpcmd,
+				  struct io_buffer *iobuf,
+				  struct xfer_metadata *meta __unused ) {
+	struct fcp_device *fcpdev = fcpcmd->fcpdev;
+	struct fcp_xfer_rdy *xfer_rdy = iobuf->data;
+	int rc;
+
+	/* Sanity checks */
+	if ( iob_len ( iobuf ) != sizeof ( *xfer_rdy ) ) {
+		DBGC ( fcpdev, "FCP %p ref %02x received invalid transfer "
+		       "ready IU:\n", fcpdev, fcpcmd->ref );
+		DBGC_HDA ( fcpdev, 0, iobuf->data, iob_len ( iobuf ) );
+		rc = -EINVAL;
+		goto done;
+	}
+	if ( ntohl ( xfer_rdy->offset ) != fcpcmd->offset ) {
+		/* We do not advertise out-of-order delivery */
+		DBGC ( fcpdev, "FCP %p ref %02x cannot support out-of-order "
+		       "delivery (expected %zd, requested %d)\n",
+		       fcpdev, fcpcmd->ref, fcpcmd->offset,
+		       ntohl ( xfer_rdy->offset ) );
+		rc = -EINVAL;
+		goto done;
+	}
+	DBGC2 ( fcpdev, "FCP %p ref %02x XFER_RDY [%08x,%08x)\n",
+		fcpdev, fcpcmd->ref, ntohl ( xfer_rdy->offset ),
+		( ntohl ( xfer_rdy->offset ) + ntohl ( xfer_rdy->len ) ) );
+
+	/* Start sending requested data */
+	fcpcmd->remaining = ntohl ( xfer_rdy->len );
+	fcpcmd_start_send ( fcpcmd, fcpcmd_send_wrdata );
+
+	rc = 0;
+ done:
+	free_iob ( iobuf );
+	return rc;
+}
+
+/**
+ * Handle FCP response IU
+ *
+ * @v fcpcmd		FCP command
+ * @v iobuf		I/O buffer
+ * @v meta		Data transfer metadata
+ * @ret rc		Return status code
+ */
+static int fcpcmd_recv_rsp ( struct fcp_command *fcpcmd,
+			     struct io_buffer *iobuf,
+			     struct xfer_metadata *meta __unused ) {
+	struct fcp_device *fcpdev = fcpcmd->fcpdev;
+	struct scsi_cmd *command = &fcpcmd->command;
+	struct fcp_rsp *rsp = iobuf->data;
+	struct scsi_sense *sense;
+	struct scsi_rsp response;
+	int rc;
+
+	/* Sanity check */
+	if ( ( iob_len ( iobuf ) < sizeof ( *rsp ) ) ||
+	     ( iob_len ( iobuf ) < ( sizeof ( *rsp ) +
+				     fcp_rsp_response_data_len ( rsp ) +
+				     fcp_rsp_sense_data_len ( rsp ) ) ) ) {
+		DBGC ( fcpdev, "FCP %p ref %02x received invalid response "
+		       "IU:\n", fcpdev, fcpcmd->ref );
+		DBGC_HDA ( fcpdev, 0, iobuf->data, iob_len ( iobuf ) );
+		rc = -EINVAL;
+		goto done;
+	}
+	DBGC2 ( fcpdev, "FCP %p ref %02x RSP stat %02x resid %08x flags %02x"
+		"%s%s%s%s\n", fcpdev, fcpcmd->ref, rsp->status,
+		ntohl ( rsp->residual ), rsp->flags,
+		( ( rsp->flags & FCP_RSP_RESPONSE_LEN_VALID ) ? " resp" : "" ),
+		( ( rsp->flags & FCP_RSP_SENSE_LEN_VALID ) ? " sense" : "" ),
+		( ( rsp->flags & FCP_RSP_RESIDUAL_OVERRUN ) ? " over" : "" ),
+		( ( rsp->flags & FCP_RSP_RESIDUAL_UNDERRUN ) ? " under" : "" ));
+	if ( fcp_rsp_response_data ( rsp ) ) {
+		DBGC2 ( fcpdev, "FCP %p ref %02x response data:\n",
+			fcpdev, fcpcmd->ref );
+		DBGC2_HDA ( fcpdev, 0, fcp_rsp_response_data ( rsp ),
+			    fcp_rsp_response_data_len ( rsp ) );
+	}
+	if ( fcp_rsp_sense_data ( rsp ) ) {
+		DBGC2 ( fcpdev, "FCP %p ref %02x sense data:\n",
+			fcpdev, fcpcmd->ref );
+		DBGC2_HDA ( fcpdev, 0, fcp_rsp_sense_data ( rsp ),
+			    fcp_rsp_sense_data_len ( rsp ) );
+	}
+
+	/* Check for locally-detected command underrun */
+	if ( ( rsp->status == 0 ) &&
+	     ( fcpcmd->offset != ( command->data_in_len +
+				   command->data_out_len ) ) ) {
+		DBGC ( fcpdev, "FCP %p ref %02x data underrun (expected %zd, "
+		       "got %zd)\n", fcpdev, fcpcmd->ref,
+		       ( command->data_in_len + command->data_out_len ),
+		       fcpcmd->offset );
+		rc = -ERANGE_DATA_UNDERRUN;
+		goto done;
+	}
+
+	/* Build SCSI response */
+	memset ( &response, 0, sizeof ( response ) );
+	response.status = rsp->status;
+	if ( rsp->flags & ( FCP_RSP_RESIDUAL_OVERRUN |
+			    FCP_RSP_RESIDUAL_UNDERRUN ) ) {
+		response.overrun = ntohl ( rsp->residual );
+		if ( rsp->flags & FCP_RSP_RESIDUAL_UNDERRUN )
+			response.overrun = -response.overrun;
+	}
+	if ( ( sense = fcp_rsp_sense_data ( rsp ) ) != NULL )
+		memcpy ( &response.sense, sense, sizeof ( response.sense ) );
+
+	/* Free buffer before sending response, to minimise
+	 * out-of-memory errors.
+	 */
+	free_iob ( iob_disown ( iobuf ) );
+
+	/* Send SCSI response */
+	scsi_response ( &fcpcmd->scsi, &response );
+
+	/* Terminate command */
+	fcpcmd_close ( fcpcmd, 0 );
+
+	rc = 0;
+ done:
+	free_iob ( iobuf );
+	return rc;
+}
+
+/**
+ * Handle unknown FCP IU
+ *
+ * @v fcpcmd		FCP command
+ * @v iobuf		I/O buffer
+ * @v meta		Data transfer metadata
+ * @ret rc		Return status code
+ */
+static int fcpcmd_recv_unknown ( struct fcp_command *fcpcmd,
+				 struct io_buffer *iobuf,
+				 struct xfer_metadata *meta __unused ) {
+	struct fcp_device *fcpdev = fcpcmd->fcpdev;
+
+	DBGC ( fcpdev, "FCP %p ref %02x received unknown IU:\n",
+	       fcpdev, fcpcmd->ref );
+	DBGC_HDA ( fcpdev, 0, iobuf->data, iob_len ( iobuf ) );
+	free_iob ( iobuf );
+	return -EINVAL;
+}
+
+/**
+ * Transmit FCP frame
+ *
+ * @v process		FCP command process
+ */
+static void fcpcmd_step ( struct process *process ) {
+	struct fcp_command *fcpcmd =
+		container_of ( process, struct fcp_command, process );
+	int rc;
+
+	/* Send the current IU */
+	if ( ( rc = fcpcmd->send ( fcpcmd ) ) != 0 ) {
+		/* Treat failure as a fatal error */
+		fcpcmd_close ( fcpcmd, rc );
+	}
+}
+
+/**
+ * Receive FCP frame
+ *
+ * @v fcpcmd		FCP command
+ * @v iobuf		I/O buffer
+ * @v meta		Data transfer metadata
+ * @ret rc		Return status code
+ */
+static int fcpcmd_deliver ( struct fcp_command *fcpcmd,
+			    struct io_buffer *iobuf,
+			    struct xfer_metadata *meta ) {
+	int ( * fcpcmd_recv ) ( struct fcp_command *fcpcmd,
+				struct io_buffer *iobuf,
+				struct xfer_metadata *meta );
+	int rc;
+
+	/* Determine handler */
+	switch ( meta->flags & ( XFER_FL_CMD_STAT | XFER_FL_RESPONSE ) ) {
+	case ( XFER_FL_RESPONSE ) :
+		fcpcmd_recv = fcpcmd_recv_rddata;
+		break;
+	case ( XFER_FL_CMD_STAT ) :
+		fcpcmd_recv = fcpcmd_recv_xfer_rdy;
+		break;
+	case ( XFER_FL_CMD_STAT | XFER_FL_RESPONSE ) :
+		fcpcmd_recv = fcpcmd_recv_rsp;
+		break;
+	default:
+		fcpcmd_recv = fcpcmd_recv_unknown;
+		break;
+	}
+
+	/* Handle IU */
+	if ( ( rc = fcpcmd_recv ( fcpcmd, iob_disown ( iobuf ), meta ) ) != 0 ){
+		/* Treat any error as fatal to the command */
+		fcpcmd_close ( fcpcmd, rc );
+	}
+
+	return rc;
+}
+
+/** FCP command SCSI interface operations */
+static struct interface_operation fcpcmd_scsi_op[] = {
+	INTF_OP ( intf_close, struct fcp_command *, fcpcmd_close ),
+};
+
+/** FCP command SCSI interface descriptor */
+static struct interface_descriptor fcpcmd_scsi_desc =
+	INTF_DESC_PASSTHRU ( struct fcp_command, scsi, fcpcmd_scsi_op, xchg );
+
+/** FCP command Fibre Channel exchange interface operations */
+static struct interface_operation fcpcmd_xchg_op[] = {
+	INTF_OP ( xfer_deliver, struct fcp_command *, fcpcmd_deliver ),
+	INTF_OP ( intf_close, struct fcp_command *, fcpcmd_close_err ),
+};
+
+/** FCP command Fibre Channel exchange interface descriptor */
+static struct interface_descriptor fcpcmd_xchg_desc =
+	INTF_DESC_PASSTHRU ( struct fcp_command, xchg, fcpcmd_xchg_op, scsi );
+
+/**
+ * Issue FCP SCSI command
+ *
+ * @v fcpdev		FCP device
+ * @v parent		Parent interface
+ * @v command		SCSI command
+ * @ret tag		Command tag, or negative error
+ */
+static int fcpdev_scsi_command ( struct fcp_device *fcpdev,
+				 struct interface *parent,
+				 struct scsi_cmd *command ) {
+	struct fcp_prli_service_parameters *param = fcpdev->ulp->param;
+	static uint8_t ref = 0;
+	struct fcp_command *fcpcmd;
+	int rc;
+
+	/* Check link */
+	if ( ( rc = fcpdev->ulp->link.rc ) != 0 ) {
+		DBGC ( fcpdev, "FCP %p could not issue command while link is "
+		       "down: %s\n", fcpdev, strerror ( rc ) );
+		goto err_link;
+	}
+
+	/* Check target capability */
+	assert ( param != NULL );
+	assert ( fcpdev->ulp->param_len >= sizeof ( *param ) );
+	if ( ! ( param->flags & htonl ( FCP_PRLI_TARGET ) ) ) {
+		DBGC ( fcpdev, "FCP %p could not issue command: not a target\n",
+		       fcpdev );
+		rc = -ENOTTY;
+		goto err_target;
+	}
+
+	/* Allocate and initialise structure */
+	fcpcmd = zalloc ( sizeof ( *fcpcmd ) );
+	if ( ! fcpcmd ) {
+		rc = -ENOMEM;
+		goto err_zalloc;
+	}
+	ref_init ( &fcpcmd->refcnt, fcpcmd_free );
+	intf_init ( &fcpcmd->scsi, &fcpcmd_scsi_desc, &fcpcmd->refcnt );
+	intf_init ( &fcpcmd->xchg, &fcpcmd_xchg_desc, &fcpcmd->refcnt );
+	process_init_stopped ( &fcpcmd->process, fcpcmd_step, &fcpcmd->refcnt );
+	fcpcmd->fcpdev = fcpdev_get ( fcpdev );
+	list_add ( &fcpcmd->list, &fcpdev->fcpcmds );
+	memcpy ( &fcpcmd->command, command, sizeof ( fcpcmd->command ) );
+	fcpcmd->ref = ref++; /* Not used for demultiplexing, only for debug */
+
+	/* Create new exchange */
+	if ( ( rc = fc_xchg_originate ( &fcpcmd->xchg, fcpdev->ulp->peer->port,
+					&fcpdev->ulp->peer->port_id,
+					FC_TYPE_FCP ) ) != 0 ) {
+		DBGC ( fcpdev, "FCP %p ref %02x could not create exchange: "
+		       "%s\n", fcpdev, fcpcmd->ref, strerror ( rc ) );
+		goto err_xchg_originate;
+	}
+
+	/* Start sending command IU */
+	fcpcmd_start_send ( fcpcmd, fcpcmd_send_cmnd );
+
+	/* Attach to parent interface, mortalise self, and return */
+	intf_plug_plug ( &fcpcmd->scsi, parent );
+	ref_put ( &fcpcmd->refcnt );
+	return ( FCP_TAG_MAGIC | fcpcmd->ref );
+
+ err_xchg_originate:
+	fcpcmd_close ( fcpcmd, rc );
+ err_zalloc:
+ err_target:
+ err_link:
+	return rc;
+}
+
+/**
+ * Close FCP device
+ *
+ * @v fcpdev		FCP device
+ * @v rc		Reason for close
+ */
+static void fcpdev_close ( struct fcp_device *fcpdev, int rc ) {
+	struct fcp_command *fcpcmd;
+	struct fcp_command *tmp;
+
+	DBGC ( fcpdev, "FCP %p closed: %s\n", fcpdev, strerror ( rc ) );
+
+	/* Shut down interfaces */
+	intf_shutdown ( &fcpdev->scsi, rc );
+
+	/* Shut down any active commands */
+	list_for_each_entry_safe ( fcpcmd, tmp, &fcpdev->fcpcmds, list ) {
+		fcpcmd_get ( fcpcmd );
+		fcpcmd_close ( fcpcmd, rc );
+		fcpcmd_put ( fcpcmd );
+	}
+
+	/* Drop reference to ULP */
+	if ( fcpdev->ulp ) {
+		fc_ulp_decrement ( fcpdev->ulp );
+		fc_ulp_put ( fcpdev->ulp );
+		fcpdev->ulp = NULL;
+	}
+}
+
+/**
+ * Check FCP device flow-control window
+ *
+ * @v fcpdev		FCP device
+ * @ret len		Length of window
+ */
+static size_t fcpdev_window ( struct fcp_device *fcpdev ) {
+	return ( fc_link_ok ( &fcpdev->ulp->link ) ? ~( ( size_t ) 0 ) : 0 );
+}
+
+/**
+ * Describe FCP device in an ACPI table
+ *
+ * @v fcpdev		FCP device
+ * @v acpi		ACPI table
+ * @v len		Length of ACPI table
+ * @ret rc		Return status code
+ */
+static int fcpdev_describe ( struct fcp_device *fcpdev,
+			     struct acpi_description_header *acpi,
+			     size_t len ) {
+
+	DBGC ( fcpdev, "FCP %p cannot yet describe device in an ACPI table\n",
+	       fcpdev );
+	( void ) acpi;
+	( void ) len;
+	return 0;
+}
+
+/** FCP device SCSI interface operations */
+static struct interface_operation fcpdev_scsi_op[] = {
+	INTF_OP ( scsi_command, struct fcp_device *, fcpdev_scsi_command ),
+	INTF_OP ( xfer_window, struct fcp_device *, fcpdev_window ),
+	INTF_OP ( intf_close, struct fcp_device *, fcpdev_close ),
+	INTF_OP ( acpi_describe, struct fcp_device *, fcpdev_describe ),
+};
+
+/** FCP device SCSI interface descriptor */
+static struct interface_descriptor fcpdev_scsi_desc =
+	INTF_DESC ( struct fcp_device, scsi, fcpdev_scsi_op );
+
+/**
+ * Open FCP device
+ *
+ * @v parent		Parent interface
+ * @v wwn		Fibre Channel WWN
+ * @v lun		SCSI LUN
+ * @ret rc		Return status code
+ */
+static int fcpdev_open ( struct interface *parent, struct fc_name *wwn,
+			 struct scsi_lun *lun ) {
+	struct fc_ulp *ulp;
+	struct fcp_device *fcpdev;
+	int rc;
+
+	/* Get Fibre Channel ULP interface */
+	ulp = fc_ulp_get_wwn_type ( wwn, FC_TYPE_FCP );
+	if ( ! ulp ) {
+		rc = -ENOMEM;
+		goto err_ulp_get;
+	}
+
+	/* Allocate and initialise structure */
+	fcpdev = zalloc ( sizeof ( *fcpdev ) );
+	if ( ! fcpdev ) {
+		rc = -ENOMEM;
+		goto err_zalloc;
+	}
+	ref_init ( &fcpdev->refcnt, NULL );
+	intf_init ( &fcpdev->scsi, &fcpdev_scsi_desc, &fcpdev->refcnt );
+	INIT_LIST_HEAD ( &fcpdev->fcpcmds );
+	fcpdev->ulp = fc_ulp_get ( ulp );
+	fc_ulp_increment ( fcpdev->ulp );
+
+	DBGC ( fcpdev, "FCP %p opened for %s\n", fcpdev, fc_ntoa ( wwn ) );
+
+	/* Attach SCSI device to parent interface */
+	if ( ( rc = scsi_open ( parent, &fcpdev->scsi, lun ) ) != 0 ) {
+		DBGC ( fcpdev, "FCP %p could not create SCSI device: %s\n",
+		       fcpdev, strerror ( rc ) );
+		goto err_scsi_open;
+	}
+
+	/* Drop temporary reference to ULP */
+	fc_ulp_put ( ulp );
+
+	/* Mortalise self and return */
+	ref_put ( &fcpdev->refcnt );
+	return 0;
+
+ err_scsi_open:
+	fcpdev_close ( fcpdev, rc );
+ err_zalloc:
+	fc_ulp_put ( ulp );
+ err_ulp_get:
+	return rc;
+}
+
+/******************************************************************************
+ *
+ * FCP URIs
+ *
+ ******************************************************************************
+ */
+
+/**
+ * Parse FCP URI
+ *
+ * @v uri		URI
+ * @ret wwn		Fibre Channel WWN
+ * @ret lun		SCSI LUN
+ * @ret rc		Return status code
+ *
+ * An FCP URI has the form "fcp:<wwn>:<lun>" or "fcp://<wwn>/<lun>"
+ */
+static int fcp_parse_uri ( struct uri *uri, struct fc_name *wwn,
+			   struct scsi_lun *lun ) {
+	char wwn_buf[ FC_NAME_STRLEN + 1 /* NUL */ ];
+	const char *wwn_text;
+	const char *lun_text;
+	int rc;
+
+	/* Extract WWN and LUN texts from URI */
+	if ( uri->opaque ) {
+		/* "fcp:<wwn>:<lun>" */
+		if ( snprintf ( wwn_buf, sizeof ( wwn_buf ), "%s",
+				uri->opaque ) < ( FC_NAME_STRLEN + 1 /* : */ ) )
+			return -EINVAL;
+		if ( uri->opaque[FC_NAME_STRLEN] != ':' )
+			return -EINVAL;
+		wwn_text = wwn_buf;
+		lun_text = &uri->opaque[FC_NAME_STRLEN + 1];
+	} else {
+		/* If host exists, path must also exist */
+		if ( ! ( uri->host && uri->path ) )
+			return -EINVAL;
+		if ( uri->path[0] != '/' )
+			return -EINVAL;
+		wwn_text = uri->host;
+		lun_text = ( uri->path + 1 );
+	}
+
+	/* Parse WWN */
+	if ( ( rc = fc_aton ( wwn_text, wwn ) ) != 0 )
+		return rc;
+
+	/* Parse LUN */
+	if ( ( rc = scsi_parse_lun ( lun_text, lun ) ) != 0 )
+		return rc;
+
+	return 0;
+}
+
+/**
+ * Open FCP URI
+ *
+ * @v parent		Parent interface
+ * @v uri		URI
+ * @ret rc		Return status code
+ */
+static int fcp_open ( struct interface *parent, struct uri *uri ) {
+	struct fc_name wwn;
+	struct scsi_lun lun;
+	int rc;
+
+	/* Parse URI */
+	if ( ( rc = fcp_parse_uri ( uri, &wwn, &lun ) ) != 0 )
+		return rc;
+
+	/* Open FCP device */
+	if ( ( rc = fcpdev_open ( parent, &wwn, &lun ) ) != 0 )
+		return rc;
+
+	return 0;
+}
+
+/** FCP URI opener */
+struct uri_opener fcp_uri_opener __uri_opener = {
+	.scheme = "fcp",
+	.open = fcp_open,
+};