1 files changed, 829 insertions, 0 deletions

diff --git a/qemu/roms/ipxe/src/drivers/block/srp.c b/qemu/roms/ipxe/src/drivers/block/srp.c
new file mode 100644
index 000000000..7edf69ace
--- /dev/null
+++ b/qemu/roms/ipxe/src/drivers/block/srp.c
@@ -0,0 +1,829 @@
+/*
+ * Copyright (C) 2009 Fen Systems Ltd <mbrown@fensystems.co.uk>.
+ * All rights reserved.
+ *
+ * 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.
+ *
+ * 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 HOLDER 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.
+ */
+
+FILE_LICENCE ( BSD2 );
+
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <ipxe/scsi.h>
+#include <ipxe/xfer.h>
+#include <ipxe/features.h>
+#include <ipxe/srp.h>
+
+/**
+ * @file
+ *
+ * SCSI RDMA Protocol
+ *
+ */
+
+FEATURE ( FEATURE_PROTOCOL, "SRP", DHCP_EB_FEATURE_SRP, 1 );
+
+/** Maximum length of any initiator-to-target IU that we will send
+ *
+ * The longest IU is a SRP_CMD with no additional CDB and two direct
+ * data buffer descriptors, which comes to 80 bytes.
+ */
+#define SRP_MAX_I_T_IU_LEN 80
+
+/* Error numbers generated by SRP login rejection */
+#define EINFO_SRP_LOGIN_REJ( reason, desc )				      \
+	__einfo_uniqify ( EINFO_EPERM, ( (reason) & 0x0f ), desc )
+#define EPERM_UNKNOWN							      \
+	__einfo_error ( EINFO_EPERM_UNKNOWN )
+#define EINFO_EPERM_UNKNOWN EINFO_SRP_LOGIN_REJ (			      \
+	SRP_LOGIN_REJ_REASON_UNKNOWN,					      \
+	"Unable to establish RDMA channel, no reason specified" )
+#define EPERM_INSUFFICIENT_RESOURCES					      \
+	__einfo_error ( EINFO_EPERM_INSUFFICIENT_RESOURCES )
+#define EINFO_EPERM_INSUFFICIENT_RESOURCES EINFO_SRP_LOGIN_REJ (	      \
+	SRP_LOGIN_REJ_REASON_INSUFFICIENT_RESOURCES,			      \
+	"Insufficient RDMA channel resources" )
+#define EPERM_BAD_MAX_I_T_IU_LEN					      \
+	__einfo_error ( EINFO_EPERM_BAD_MAX_I_T_IU_LEN )
+#define EINFO_EPERM_BAD_MAX_I_T_IU_LEN EINFO_SRP_LOGIN_REJ (		      \
+	SRP_LOGIN_REJ_REASON_BAD_MAX_I_T_IU_LEN,			      \
+	"Requested maximum initiator to target IU length value too large" )
+#define EPERM_CANNOT_ASSOCIATE						      \
+	__einfo_error ( EINFO_EPERM_CANNOT_ASSOCIATE )
+#define EINFO_EPERM_CANNOT_ASSOCIATE EINFO_SRP_LOGIN_REJ (		      \
+	SRP_LOGIN_REJ_REASON_CANNOT_ASSOCIATE,				      \
+	"Unable to associate RDMA channel with specified I_T nexus" )
+#define EPERM_UNSUPPORTED_BUFFER_FORMAT					      \
+	__einfo_error ( EINFO_EPERM_UNSUPPORTED_BUFFER_FORMAT )
+#define EINFO_EPERM_UNSUPPORTED_BUFFER_FORMAT EINFO_SRP_LOGIN_REJ (	      \
+	SRP_LOGIN_REJ_REASON_UNSUPPORTED_BUFFER_FORMAT,			      \
+	"One or more requested data buffer descriptor formats not supported" )
+#define EPERM_NO_MULTIPLE_CHANNELS					      \
+	__einfo_error ( EINFO_EPERM_NO_MULTIPLE_CHANNELS )
+#define EINFO_EPERM_NO_MULTIPLE_CHANNELS EINFO_SRP_LOGIN_REJ (		      \
+	SRP_LOGIN_REJ_REASON_NO_MULTIPLE_CHANNELS,			      \
+	"SRP target does not support multiple RDMA channels per I_T nexus" )
+#define EPERM_NO_MORE_CHANNELS						      \
+	__einfo_error ( EINFO_EPERM_NO_MORE_CHANNELS )
+#define EINFO_EPERM_NO_MORE_CHANNELS EINFO_SRP_LOGIN_REJ (		      \
+	SRP_LOGIN_REJ_REASON_NO_MORE_CHANNELS,				      \
+	"RDMA channel limit reached for this initiator" )
+#define EPERM_LOGIN_REJ( reason_nibble )				      \
+	EUNIQ ( EINFO_EPERM, (reason_nibble), EPERM_UNKNOWN,		      \
+		EPERM_INSUFFICIENT_RESOURCES, EPERM_BAD_MAX_I_T_IU_LEN,	      \
+		EPERM_CANNOT_ASSOCIATE, EPERM_UNSUPPORTED_BUFFER_FORMAT,      \
+		EPERM_NO_MULTIPLE_CHANNELS, EPERM_NO_MORE_CHANNELS )
+
+/** An SRP device */
+struct srp_device {
+	/** Reference count */
+	struct refcnt refcnt;
+
+	/** SCSI command issuing interface */
+	struct interface scsi;
+	/** Underlying data transfer interface */
+	struct interface socket;
+
+	/** RDMA memory handle */
+	uint32_t memory_handle;
+	/** Login completed successfully */
+	int logged_in;
+
+	/** Initiator port ID (for boot firmware table) */
+	union srp_port_id initiator;
+	/** Target port ID (for boot firmware table) */
+	union srp_port_id target;
+	/** SCSI LUN (for boot firmware table) */
+	struct scsi_lun lun;
+
+	/** List of active commands */
+	struct list_head commands;
+};
+
+/** An SRP command */
+struct srp_command {
+	/** Reference count */
+	struct refcnt refcnt;
+	/** SRP device */
+	struct srp_device *srpdev;
+	/** List of active commands */
+	struct list_head list;
+
+	/** SCSI command interface */
+	struct interface scsi;
+	/** Command tag */
+	uint32_t tag;
+};
+
+/**
+ * Get reference to SRP device
+ *
+ * @v srpdev		SRP device
+ * @ret srpdev		SRP device
+ */
+static inline __attribute__ (( always_inline )) struct srp_device *
+srpdev_get ( struct srp_device *srpdev ) {
+	ref_get ( &srpdev->refcnt );
+	return srpdev;
+}
+
+/**
+ * Drop reference to SRP device
+ *
+ * @v srpdev		SRP device
+ */
+static inline __attribute__ (( always_inline )) void
+srpdev_put ( struct srp_device *srpdev ) {
+	ref_put ( &srpdev->refcnt );
+}
+
+/**
+ * Get reference to SRP command
+ *
+ * @v srpcmd		SRP command
+ * @ret srpcmd		SRP command
+ */
+static inline __attribute__ (( always_inline )) struct srp_command *
+srpcmd_get ( struct srp_command *srpcmd ) {
+	ref_get ( &srpcmd->refcnt );
+	return srpcmd;
+}
+
+/**
+ * Drop reference to SRP command
+ *
+ * @v srpcmd		SRP command
+ */
+static inline __attribute__ (( always_inline )) void
+srpcmd_put ( struct srp_command *srpcmd ) {
+	ref_put ( &srpcmd->refcnt );
+}
+
+/**
+ * Free SRP command
+ *
+ * @v refcnt		Reference count
+ */
+static void srpcmd_free ( struct refcnt *refcnt ) {
+	struct srp_command *srpcmd =
+		container_of ( refcnt, struct srp_command, refcnt );
+
+	assert ( list_empty ( &srpcmd->list ) );
+
+	srpdev_put ( srpcmd->srpdev );
+	free ( srpcmd );
+}
+
+/**
+ * Close SRP command
+ *
+ * @v srpcmd		SRP command
+ * @v rc		Reason for close
+ */
+static void srpcmd_close ( struct srp_command *srpcmd, int rc ) {
+	struct srp_device *srpdev = srpcmd->srpdev;
+
+	if ( rc != 0 ) {
+		DBGC ( srpdev, "SRP %p tag %08x closed: %s\n",
+		       srpdev, srpcmd->tag, strerror ( rc ) );
+	}
+
+	/* Remove from list of commands */
+	if ( ! list_empty ( &srpcmd->list ) ) {
+		list_del ( &srpcmd->list );
+		INIT_LIST_HEAD ( &srpcmd->list );
+		srpcmd_put ( srpcmd );
+	}
+
+	/* Shut down interfaces */
+	intf_shutdown ( &srpcmd->scsi, rc );
+}
+
+/**
+ * Close SRP device
+ *
+ * @v srpdev		SRP device
+ * @v rc		Reason for close
+ */
+static void srpdev_close ( struct srp_device *srpdev, int rc ) {
+	struct srp_command *srpcmd;
+	struct srp_command *tmp;
+
+	if ( rc != 0 ) {
+		DBGC ( srpdev, "SRP %p closed: %s\n",
+		       srpdev, strerror ( rc ) );
+	}
+
+	/* Shut down interfaces */
+	intf_shutdown ( &srpdev->socket, rc );
+	intf_shutdown ( &srpdev->scsi, rc );
+
+	/* Shut down any active commands */
+	list_for_each_entry_safe ( srpcmd, tmp, &srpdev->commands, list ) {
+		srpcmd_get ( srpcmd );
+		srpcmd_close ( srpcmd, rc );
+		srpcmd_put ( srpcmd );
+	}
+}
+
+/**
+ * Identify SRP command by tag
+ *
+ * @v srpdev		SRP device
+ * @v tag		Command tag
+ * @ret srpcmd		SRP command, or NULL
+ */
+static struct srp_command * srp_find_tag ( struct srp_device *srpdev,
+					   uint32_t tag ) {
+	struct srp_command *srpcmd;
+
+	list_for_each_entry ( srpcmd, &srpdev->commands, list ) {
+		if ( srpcmd->tag == tag )
+			return srpcmd;
+	}
+	return NULL;
+}
+
+/**
+ * Choose an SRP command tag
+ *
+ * @v srpdev		SRP device
+ * @ret tag		New tag, or negative error
+ */
+static int srp_new_tag ( struct srp_device *srpdev ) {
+	static uint16_t tag_idx;
+	unsigned int i;
+
+	for ( i = 0 ; i < 65536 ; i++ ) {
+		tag_idx++;
+		if ( srp_find_tag ( srpdev, tag_idx ) == NULL )
+			return tag_idx;
+	}
+	return -EADDRINUSE;
+}
+
+/**
+ * Transmit SRP login request
+ *
+ * @v srpdev		SRP device
+ * @v initiator		Initiator port ID
+ * @v target		Target port ID
+ * @v tag		Command tag
+ * @ret rc		Return status code
+ */
+static int srp_login ( struct srp_device *srpdev, union srp_port_id *initiator,
+		       union srp_port_id *target, uint32_t tag ) {
+	struct io_buffer *iobuf;
+	struct srp_login_req *login_req;
+	int rc;
+
+	/* Allocate I/O buffer */
+	iobuf = xfer_alloc_iob ( &srpdev->socket, sizeof ( *login_req ) );
+	if ( ! iobuf )
+		return -ENOMEM;
+
+	/* Construct login request IU */
+	login_req = iob_put ( iobuf, sizeof ( *login_req ) );
+	memset ( login_req, 0, sizeof ( *login_req ) );
+	login_req->type = SRP_LOGIN_REQ;
+	login_req->tag.dwords[0] = htonl ( SRP_TAG_MAGIC );
+	login_req->tag.dwords[1] = htonl ( tag );
+	login_req->max_i_t_iu_len = htonl ( SRP_MAX_I_T_IU_LEN );
+	login_req->required_buffer_formats = SRP_LOGIN_REQ_FMT_DDBD;
+	memcpy ( &login_req->initiator, initiator,
+		 sizeof ( login_req->initiator ) );
+	memcpy ( &login_req->target, target, sizeof ( login_req->target ) );
+
+	DBGC ( srpdev, "SRP %p tag %08x LOGIN_REQ:\n", srpdev, tag );
+	DBGC_HDA ( srpdev, 0, iobuf->data, iob_len ( iobuf ) );
+
+	/* Send login request IU */
+	if ( ( rc = xfer_deliver_iob ( &srpdev->socket, iobuf ) ) != 0 ) {
+		DBGC ( srpdev, "SRP %p tag %08x could not send LOGIN_REQ: "
+		       "%s\n", srpdev, tag, strerror ( rc ) );
+		return rc;
+	}
+
+	return 0;
+}
+
+/**
+ * Receive SRP login response
+ *
+ * @v srpdev		SRP device
+ * @v data		SRP IU
+ * @v len		Length of SRP IU
+ * @ret rc		Return status code
+ */
+static int srp_login_rsp ( struct srp_device *srpdev,
+			   const void *data, size_t len ) {
+	const struct srp_login_rsp *login_rsp = data;
+
+	/* Sanity check */
+	if ( len < sizeof ( *login_rsp ) ) {
+		DBGC ( srpdev, "SRP %p LOGIN_RSP too short (%zd bytes)\n",
+		       srpdev, len );
+		return -EINVAL;
+	}
+	DBGC ( srpdev, "SRP %p tag %08x LOGIN_RSP:\n",
+	       srpdev, ntohl ( login_rsp->tag.dwords[1] ) );
+	DBGC_HDA ( srpdev, 0, data, len );
+
+	/* Mark as logged in */
+	srpdev->logged_in = 1;
+	DBGC ( srpdev, "SRP %p logged in\n", srpdev );
+
+	/* Notify of window change */
+	xfer_window_changed ( &srpdev->scsi );
+
+	return 0;
+}
+
+/**
+ * Receive SRP login rejection
+ *
+ * @v srpdev		SRP device
+ * @v data		SRP IU
+ * @v len		Length of SRP IU
+ * @ret rc		Return status code
+ */
+static int srp_login_rej ( struct srp_device *srpdev,
+			   const void *data, size_t len ) {
+	const struct srp_login_rej *login_rej = data;
+	uint32_t reason;
+
+	/* Sanity check */
+	if ( len < sizeof ( *login_rej ) ) {
+		DBGC ( srpdev, "SRP %p LOGIN_REJ too short (%zd bytes)\n",
+		       srpdev, len );
+		return -EINVAL;
+	}
+	reason = ntohl ( login_rej->reason );
+	DBGC ( srpdev, "SRP %p tag %08x LOGIN_REJ reason %08x:\n",
+	       srpdev, ntohl ( login_rej->tag.dwords[1] ), reason );
+	DBGC_HDA ( srpdev, 0, data, len );
+
+	/* Login rejection always indicates an error */
+	return ( SRP_LOGIN_REJ_REASON_DEFINED ( reason ) ?
+		 -EPERM_LOGIN_REJ ( reason ) : -EACCES );
+}
+
+/**
+ * Transmit SRP SCSI command
+ *
+ * @v srpdev		SRP device
+ * @v command		SCSI command
+ * @v tag		Command tag
+ * @ret rc		Return status code
+ */
+static int srp_cmd ( struct srp_device *srpdev,
+		     struct scsi_cmd *command,
+		     uint32_t tag ) {
+	struct io_buffer *iobuf;
+	struct srp_cmd *cmd;
+	struct srp_memory_descriptor *data_out;
+	struct srp_memory_descriptor *data_in;
+	int rc;
+
+	/* Sanity check */
+	if ( ! srpdev->logged_in ) {
+		DBGC ( srpdev, "SRP %p tag %08x cannot send CMD before "
+		       "login completes\n", srpdev, tag );
+		return -EBUSY;
+	}
+
+	/* Allocate I/O buffer */
+	iobuf = xfer_alloc_iob ( &srpdev->socket, SRP_MAX_I_T_IU_LEN );
+	if ( ! iobuf )
+		return -ENOMEM;
+
+	/* Construct base portion */
+	cmd = iob_put ( iobuf, sizeof ( *cmd ) );
+	memset ( cmd, 0, sizeof ( *cmd ) );
+	cmd->type = SRP_CMD;
+	cmd->tag.dwords[0] = htonl ( SRP_TAG_MAGIC );
+	cmd->tag.dwords[1] = htonl ( tag );
+	memcpy ( &cmd->lun, &command->lun, sizeof ( cmd->lun ) );
+	memcpy ( &cmd->cdb, &command->cdb, sizeof ( cmd->cdb ) );
+
+	/* Construct data-out descriptor, if present */
+	if ( command->data_out ) {
+		cmd->data_buffer_formats |= SRP_CMD_DO_FMT_DIRECT;
+		data_out = iob_put ( iobuf, sizeof ( *data_out ) );
+		data_out->address =
+		    cpu_to_be64 ( user_to_phys ( command->data_out, 0 ) );
+		data_out->handle = ntohl ( srpdev->memory_handle );
+		data_out->len = ntohl ( command->data_out_len );
+	}
+
+	/* Construct data-in descriptor, if present */
+	if ( command->data_in ) {
+		cmd->data_buffer_formats |= SRP_CMD_DI_FMT_DIRECT;
+		data_in = iob_put ( iobuf, sizeof ( *data_in ) );
+		data_in->address =
+		     cpu_to_be64 ( user_to_phys ( command->data_in, 0 ) );
+		data_in->handle = ntohl ( srpdev->memory_handle );
+		data_in->len = ntohl ( command->data_in_len );
+	}
+
+	DBGC2 ( srpdev, "SRP %p tag %08x CMD " SCSI_CDB_FORMAT "\n",
+		srpdev, tag, SCSI_CDB_DATA ( cmd->cdb ) );
+
+	/* Send IU */
+	if ( ( rc = xfer_deliver_iob ( &srpdev->socket, iobuf ) ) != 0 ) {
+		DBGC ( srpdev, "SRP %p tag %08x could not send CMD: %s\n",
+		       srpdev, tag, strerror ( rc ) );
+		return rc;
+	}
+
+	return 0;
+}
+
+/**
+ * Receive SRP SCSI response
+ *
+ * @v srpdev		SRP device
+ * @v data		SRP IU
+ * @v len		Length of SRP IU
+ * @ret rc		Returns status code
+ */
+static int srp_rsp ( struct srp_device *srpdev,
+		     const void *data, size_t len ) {
+	const struct srp_rsp *rsp = data;
+	struct srp_command *srpcmd;
+	struct scsi_rsp response;
+	ssize_t data_out_residual_count;
+	ssize_t data_in_residual_count;
+
+	/* Sanity check */
+	if ( ( len < sizeof ( *rsp ) ) ||
+	     ( len < ( sizeof ( *rsp ) +
+		       srp_rsp_response_data_len ( rsp ) +
+		       srp_rsp_sense_data_len ( rsp ) ) ) ) {
+		DBGC ( srpdev, "SRP %p RSP too short (%zd bytes)\n",
+		       srpdev, len );
+		return -EINVAL;
+	}
+	DBGC2 ( srpdev, "SRP %p tag %08x RSP stat %02x dores %08x dires "
+		"%08x valid %02x%s%s%s%s%s%s\n",
+		srpdev, ntohl ( rsp->tag.dwords[1] ), rsp->status,
+		ntohl ( rsp->data_out_residual_count ),
+		ntohl ( rsp->data_in_residual_count ), rsp->valid,
+		( ( rsp->valid & SRP_RSP_VALID_DIUNDER ) ? " diunder" : "" ),
+		( ( rsp->valid & SRP_RSP_VALID_DIOVER ) ? " diover" : "" ),
+		( ( rsp->valid & SRP_RSP_VALID_DOUNDER ) ? " dounder" : "" ),
+		( ( rsp->valid & SRP_RSP_VALID_DOOVER ) ? " doover" : "" ),
+		( ( rsp->valid & SRP_RSP_VALID_SNSVALID ) ? " sns" : "" ),
+		( ( rsp->valid & SRP_RSP_VALID_RSPVALID ) ? " rsp" : "" ) );
+
+	/* Identify command by tag */
+	srpcmd = srp_find_tag ( srpdev, ntohl ( rsp->tag.dwords[1] ) );
+	if ( ! srpcmd ) {
+		DBGC ( srpdev, "SRP %p tag %08x unrecognised RSP\n",
+		       srpdev, ntohl ( rsp->tag.dwords[1] ) );
+		return -ENOENT;
+	}
+
+	/* Hold command reference for remainder of function */
+	srpcmd_get ( srpcmd );
+
+	/* Build SCSI response */
+	memset ( &response, 0, sizeof ( response ) );
+	response.status = rsp->status;
+	data_out_residual_count = ntohl ( rsp->data_out_residual_count );
+	data_in_residual_count = ntohl ( rsp->data_in_residual_count );
+	if ( rsp->valid & SRP_RSP_VALID_DOOVER ) {
+		response.overrun = data_out_residual_count;
+	} else if ( rsp->valid & SRP_RSP_VALID_DOUNDER ) {
+		response.overrun = -(data_out_residual_count);
+	} else if ( rsp->valid & SRP_RSP_VALID_DIOVER ) {
+		response.overrun = data_in_residual_count;
+	} else if ( rsp->valid & SRP_RSP_VALID_DIUNDER ) {
+		response.overrun = -(data_in_residual_count);
+	}
+	scsi_parse_sense ( srp_rsp_sense_data ( rsp ),
+			   srp_rsp_sense_data_len ( rsp ), &response.sense );
+
+	/* Report SCSI response */
+	scsi_response ( &srpcmd->scsi, &response );
+
+	/* Close SCSI command */
+	srpcmd_close ( srpcmd, 0 );
+
+	/* Drop temporary command reference */
+	srpcmd_put ( srpcmd );
+
+	return 0;
+}
+
+/**
+ * Receive SRP unrecognised response IU
+ *
+ * @v srpdev		SRP device
+ * @v data		SRP IU
+ * @v len		Length of SRP IU
+ * @ret rc		Returns status code
+ */
+static int srp_unrecognised ( struct srp_device *srpdev,
+			      const void *data, size_t len ) {
+	const struct srp_common *common = data;
+
+	DBGC ( srpdev, "SRP %p tag %08x unrecognised IU type %02x:\n",
+	       srpdev, ntohl ( common->tag.dwords[1] ), common->type );
+	DBGC_HDA ( srpdev, 0, data, len );
+
+	return -ENOTSUP;
+}
+
+/** SRP command SCSI interface operations */
+static struct interface_operation srpcmd_scsi_op[] = {
+	INTF_OP ( intf_close, struct srp_command *, srpcmd_close ),
+};
+
+/** SRP command SCSI interface descriptor */
+static struct interface_descriptor srpcmd_scsi_desc =
+	INTF_DESC ( struct srp_command, scsi, srpcmd_scsi_op );
+
+/**
+ * Issue SRP SCSI command
+ *
+ * @v srpdev		SRP device
+ * @v parent		Parent interface
+ * @v command		SCSI command
+ * @ret tag		Command tag, or negative error
+ */
+static int srpdev_scsi_command ( struct srp_device *srpdev,
+				 struct interface *parent,
+				 struct scsi_cmd *command ) {
+	struct srp_command *srpcmd;
+	int tag;
+	int rc;
+
+	/* Allocate command tag */
+	tag = srp_new_tag ( srpdev );
+	if ( tag < 0 ) {
+		rc = tag;
+		goto err_tag;
+	}
+
+	/* Allocate and initialise structure */
+	srpcmd = zalloc ( sizeof ( *srpcmd ) );
+	if ( ! srpcmd ) {
+		rc = -ENOMEM;
+		goto err_zalloc;
+	}
+	ref_init ( &srpcmd->refcnt, srpcmd_free );
+	intf_init ( &srpcmd->scsi, &srpcmd_scsi_desc, &srpcmd->refcnt );
+	srpcmd->srpdev = srpdev_get ( srpdev );
+	list_add ( &srpcmd->list, &srpdev->commands );
+	srpcmd->tag = tag;
+
+	/* Send command IU */
+	if ( ( rc = srp_cmd ( srpdev, command, srpcmd->tag ) ) != 0 )
+		goto err_cmd;
+
+	/* Attach to parent interface, leave reference with command
+	 * list, and return.
+	 */
+	intf_plug_plug ( &srpcmd->scsi, parent );
+	return srpcmd->tag;
+
+ err_cmd:
+	srpcmd_close ( srpcmd, rc );
+ err_zalloc:
+ err_tag:
+	return rc;
+}
+
+/**
+ * Receive data from SRP socket
+ *
+ * @v srpdev		SRP device
+ * @v iobuf		Datagram I/O buffer
+ * @v meta		Data transfer metadata
+ * @ret rc		Return status code
+ */
+static int srpdev_deliver ( struct srp_device *srpdev,
+			    struct io_buffer *iobuf,
+			    struct xfer_metadata *meta __unused ) {
+	struct srp_common *common = iobuf->data;
+	int ( * type ) ( struct srp_device *srp, const void *data, size_t len );
+	int rc;
+
+	/* Sanity check */
+	if ( iob_len ( iobuf ) < sizeof ( *common ) ) {
+		DBGC ( srpdev, "SRP %p IU too short (%zd bytes)\n",
+		       srpdev, iob_len ( iobuf ) );
+		rc = -EINVAL;
+		goto err;
+	}
+
+	/* Determine IU type */
+	switch ( common->type ) {
+	case SRP_LOGIN_RSP:
+		type = srp_login_rsp;
+		break;
+	case SRP_LOGIN_REJ:
+		type = srp_login_rej;
+		break;
+	case SRP_RSP:
+		type = srp_rsp;
+		break;
+	default:
+		type = srp_unrecognised;
+		break;
+	}
+
+	/* Handle IU */
+	if ( ( rc = type ( srpdev, iobuf->data, iob_len ( iobuf ) ) ) != 0 )
+		goto err;
+
+	free_iob ( iobuf );
+	return 0;
+
+ err:
+	DBGC ( srpdev, "SRP %p closing due to received IU (%s):\n",
+	       srpdev, strerror ( rc ) );
+	DBGC_HDA ( srpdev, 0, iobuf->data, iob_len ( iobuf ) );
+	free_iob ( iobuf );
+	srpdev_close ( srpdev, rc );
+	return rc;
+}
+
+/**
+ * Check SRP device flow-control window
+ *
+ * @v srpdev		SRP device
+ * @ret len		Length of window
+ */
+static size_t srpdev_window ( struct srp_device *srpdev ) {
+	return ( srpdev->logged_in ? ~( ( size_t ) 0 ) : 0 );
+}
+
+/**
+ * A (transport-independent) sBFT created by iPXE
+ */
+struct ipxe_sbft {
+	/** The table header */
+	struct sbft_table table;
+	/** The SCSI subtable */
+	struct sbft_scsi_subtable scsi;
+	/** The SRP subtable */
+	struct sbft_srp_subtable srp;
+} __attribute__ (( packed, aligned ( 16 ) ));
+
+/**
+ * Describe SRP device in an ACPI table
+ *
+ * @v srpdev		SRP device
+ * @v acpi		ACPI table
+ * @v len		Length of ACPI table
+ * @ret rc		Return status code
+ */
+static int srpdev_describe ( struct srp_device *srpdev,
+			     struct acpi_description_header *acpi,
+			     size_t len ) {
+	struct ipxe_sbft *sbft =
+		container_of ( acpi, struct ipxe_sbft, table.acpi );
+	int rc;
+
+	/* Sanity check */
+	if ( len < sizeof ( *sbft ) )
+		return -ENOBUFS;
+
+	/* Populate table */
+	sbft->table.acpi.signature = cpu_to_le32 ( SBFT_SIG );
+	sbft->table.acpi.length = cpu_to_le32 ( sizeof ( *sbft ) );
+	sbft->table.acpi.revision = 1;
+	sbft->table.scsi_offset =
+		cpu_to_le16 ( offsetof ( typeof ( *sbft ), scsi ) );
+	memcpy ( &sbft->scsi.lun, &srpdev->lun, sizeof ( sbft->scsi.lun ) );
+	sbft->table.srp_offset =
+		cpu_to_le16 ( offsetof ( typeof ( *sbft ), srp ) );
+	memcpy ( &sbft->srp.initiator, &srpdev->initiator,
+		 sizeof ( sbft->srp.initiator ) );
+	memcpy ( &sbft->srp.target, &srpdev->target,
+		 sizeof ( sbft->srp.target ) );
+
+	/* Ask transport layer to describe transport-specific portions */
+	if ( ( rc = acpi_describe ( &srpdev->socket, acpi, len ) ) != 0 ) {
+		DBGC ( srpdev, "SRP %p cannot describe transport layer: %s\n",
+		       srpdev, strerror ( rc ) );
+		return rc;
+	}
+
+	return 0;
+}
+
+/** SRP device socket interface operations */
+static struct interface_operation srpdev_socket_op[] = {
+	INTF_OP ( xfer_deliver, struct srp_device *, srpdev_deliver ),
+	INTF_OP ( intf_close, struct srp_device *, srpdev_close ),
+};
+
+/** SRP device socket interface descriptor */
+static struct interface_descriptor srpdev_socket_desc =
+	INTF_DESC_PASSTHRU ( struct srp_device, socket, srpdev_socket_op,
+			     scsi );
+
+/** SRP device SCSI interface operations */
+static struct interface_operation srpdev_scsi_op[] = {
+	INTF_OP ( scsi_command, struct srp_device *, srpdev_scsi_command ),
+	INTF_OP ( xfer_window, struct srp_device *, srpdev_window ),
+	INTF_OP ( intf_close, struct srp_device *, srpdev_close ),
+	INTF_OP ( acpi_describe, struct srp_device *, srpdev_describe ),
+};
+
+/** SRP device SCSI interface descriptor */
+static struct interface_descriptor srpdev_scsi_desc =
+	INTF_DESC_PASSTHRU ( struct srp_device, scsi, srpdev_scsi_op, socket  );
+
+/**
+ * Open SRP device
+ *
+ * @v block		Block control interface
+ * @v socket		Socket interface
+ * @v initiator		Initiator port ID
+ * @v target		Target port ID
+ * @v memory_handle	RDMA memory handle
+ * @v lun		SCSI LUN
+ * @ret rc		Return status code
+ */
+int srp_open ( struct interface *block, struct interface *socket,
+	       union srp_port_id *initiator, union srp_port_id *target,
+	       uint32_t memory_handle, struct scsi_lun *lun ) {
+	struct srp_device *srpdev;
+	int tag;
+	int rc;
+
+	/* Allocate and initialise structure */
+	srpdev = zalloc ( sizeof ( *srpdev ) );
+	if ( ! srpdev ) {
+		rc = -ENOMEM;
+		goto err_zalloc;
+	}
+	ref_init ( &srpdev->refcnt, NULL );
+	intf_init ( &srpdev->scsi, &srpdev_scsi_desc, &srpdev->refcnt );
+	intf_init ( &srpdev->socket, &srpdev_socket_desc, &srpdev->refcnt );
+	INIT_LIST_HEAD ( &srpdev->commands );
+	srpdev->memory_handle = memory_handle;
+	DBGC ( srpdev, "SRP %p %08x%08x%08x%08x->%08x%08x%08x%08x\n", srpdev,
+	       ntohl ( initiator->dwords[0] ), ntohl ( initiator->dwords[1] ),
+	       ntohl ( initiator->dwords[2] ), ntohl ( initiator->dwords[3] ),
+	       ntohl ( target->dwords[0] ), ntohl ( target->dwords[1] ),
+	       ntohl ( target->dwords[2] ), ntohl ( target->dwords[3] ) );
+
+	/* Preserve parameters required for boot firmware table */
+	memcpy ( &srpdev->initiator, initiator, sizeof ( srpdev->initiator ) );
+	memcpy ( &srpdev->target, target, sizeof ( srpdev->target ) );
+	memcpy ( &srpdev->lun, lun, sizeof ( srpdev->lun ) );
+
+	/* Attach to socket interface and initiate login */
+	intf_plug_plug ( &srpdev->socket, socket );
+	tag = srp_new_tag ( srpdev );
+	assert ( tag >= 0 ); /* Cannot fail when no commands in progress */
+	if ( ( rc = srp_login ( srpdev, initiator, target, tag ) ) != 0 )
+		goto err_login;
+
+	/* Attach SCSI device to parent interface */
+	if ( ( rc = scsi_open ( block, &srpdev->scsi, lun ) ) != 0 ) {
+		DBGC ( srpdev, "SRP %p could not create SCSI device: %s\n",
+		       srpdev, strerror ( rc ) );
+		goto err_scsi_open;
+	}
+
+	/* Mortalise self and return */
+	ref_put ( &srpdev->refcnt );
+	return 0;
+
+ err_scsi_open:
+ err_login:
+	srpdev_close ( srpdev, rc );
+	ref_put ( &srpdev->refcnt );
+ err_zalloc:
+	return rc;
+}