nvme-fabrics: Add FC transport LLDD api definitions

Host:
 - LLDD registration with the host transport
 - registering host ports (local ports) and target ports seen on
   fabric (remote ports)
 - Data structures and call points for FC-4 LS's and FCP IO requests

Target:
 - LLDD registration with the target transport
 - registering nvme subsystem ports (target ports)
 - Data structures and call points for reception of FC-4 LS's and
   FCP IO requests, and callbacks to perform data and rsp transfers
   for the io.

Add to MAINTAINERS file
Signed-off-by: James Smart <james.smart@broadcom.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jay Freyensee <james_p_freyensee@linux.intel.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>

MAINTAINERS

@@ -8664,6 +8664,7 @@ M:	James Smart <james.smart@broadcom.com>
 L:	linux-nvme@lists.infradead.org
 S:	Supported
 F:	include/linux/nvme-fc.h
+F:	include/linux/nvme-fc-driver.h
 
 NVMEM FRAMEWORK
 M:	Srinivas Kandagatla <srinivas.kandagatla@linaro.org>

include/linux/nvme-fc-driver.h

+/*
+ * Copyright (c) 2016, Avago Technologies
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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.
+ */
+
+#ifndef _NVME_FC_DRIVER_H
+#define _NVME_FC_DRIVER_H 1
+
+
+/*
+ * **********************  LLDD FC-NVME Host API ********************
+ *
+ *  For FC LLDD's that are the NVME Host role.
+ *
+ * ******************************************************************
+ */
+
+
+
+/* FC Port role bitmask - can merge with FC Port Roles in fc transport */
+#define FC_PORT_ROLE_NVME_INITIATOR	0x10
+#define FC_PORT_ROLE_NVME_TARGET	0x11
+#define FC_PORT_ROLE_NVME_DISCOVERY	0x12
+
+
+/**
+ * struct nvme_fc_port_info - port-specific ids and FC connection-specific
+ *                            data element used during NVME Host role
+ *                            registrations
+ *
+ * Static fields describing the port being registered:
+ * @node_name: FC WWNN for the port
+ * @port_name: FC WWPN for the port
+ * @port_role: What NVME roles are supported (see FC_PORT_ROLE_xxx)
+ *
+ * Initialization values for dynamic port fields:
+ * @port_id:      FC N_Port_ID currently assigned the port. Upper 8 bits must
+ *                be set to 0.
+ */
+struct nvme_fc_port_info {
+	u64			node_name;
+	u64			port_name;
+	u32			port_role;
+	u32			port_id;
+};
+
+
+/**
+ * struct nvmefc_ls_req - Request structure passed from NVME-FC transport
+ *                        to LLDD in order to perform a NVME FC-4 LS
+ *                        request and obtain a response.
+ *
+ * Values set by the NVME-FC layer prior to calling the LLDD ls_req
+ * entrypoint.
+ * @rqstaddr: pointer to request buffer
+ * @rqstdma:  PCI DMA address of request buffer
+ * @rqstlen:  Length, in bytes, of request buffer
+ * @rspaddr:  pointer to response buffer
+ * @rspdma:   PCI DMA address of response buffer
+ * @rsplen:   Length, in bytes, of response buffer
+ * @timeout:  Maximum amount of time, in seconds, to wait for the LS response.
+ *            If timeout exceeded, LLDD to abort LS exchange and complete
+ *            LS request with error status.
+ * @private:  pointer to memory allocated alongside the ls request structure
+ *            that is specifically for the LLDD to use while processing the
+ *            request. The length of the buffer corresponds to the
+ *            lsrqst_priv_sz value specified in the nvme_fc_port_template
+ *            supplied by the LLDD.
+ * @done:     The callback routine the LLDD is to invoke upon completion of
+ *            the LS request. req argument is the pointer to the original LS
+ *            request structure. Status argument must be 0 upon success, a
+ *            negative errno on failure (example: -ENXIO).
+ */
+struct nvmefc_ls_req {
+	void			*rqstaddr;
+	dma_addr_t		rqstdma;
+	u32			rqstlen;
+	void			*rspaddr;
+	dma_addr_t		rspdma;
+	u32			rsplen;
+	u32			timeout;
+
+	void			*private;
+
+	void (*done)(struct nvmefc_ls_req *req, int status);
+
+} __aligned(sizeof(u64));	/* alignment for other things alloc'd with */
+
+
+enum nvmefc_fcp_datadir {
+	NVMEFC_FCP_NODATA,	/* payload_length and sg_cnt will be zero */
+	NVMEFC_FCP_WRITE,
+	NVMEFC_FCP_READ,
+};
+
+
+#define NVME_FC_MAX_SEGMENTS		256
+
+/**
+ * struct nvmefc_fcp_req - Request structure passed from NVME-FC transport
+ *                         to LLDD in order to perform a NVME FCP IO operation.
+ *
+ * Values set by the NVME-FC layer prior to calling the LLDD fcp_io
+ * entrypoint.
+ * @cmdaddr:   pointer to the FCP CMD IU buffer
+ * @rspaddr:   pointer to the FCP RSP IU buffer
+ * @cmddma:    PCI DMA address of the FCP CMD IU buffer
+ * @rspdma:    PCI DMA address of the FCP RSP IU buffer
+ * @cmdlen:    Length, in bytes, of the FCP CMD IU buffer
+ * @rsplen:    Length, in bytes, of the FCP RSP IU buffer
+ * @payload_length: Length of DATA_IN or DATA_OUT payload data to transfer
+ * @sg_table:  scatter/gather structure for payload data
+ * @first_sgl: memory for 1st scatter/gather list segment for payload data
+ * @sg_cnt:    number of elements in the scatter/gather list
+ * @io_dir:    direction of the FCP request (see NVMEFC_FCP_xxx)
+ * @sqid:      The nvme SQID the command is being issued on
+ * @done:      The callback routine the LLDD is to invoke upon completion of
+ *             the FCP operation. req argument is the pointer to the original
+ *             FCP IO operation.
+ * @private:   pointer to memory allocated alongside the FCP operation
+ *             request structure that is specifically for the LLDD to use
+ *             while processing the operation. The length of the buffer
+ *             corresponds to the fcprqst_priv_sz value specified in the
+ *             nvme_fc_port_template supplied by the LLDD.
+ *
+ * Values set by the LLDD indicating completion status of the FCP operation.
+ * Must be set prior to calling the done() callback.
+ * @transferred_length: amount of payload data, in bytes, that were
+ *             transferred. Should equal payload_length on success.
+ * @rcv_rsplen: length, in bytes, of the FCP RSP IU received.
+ * @status:    Completion status of the FCP operation. must be 0 upon success,
+ *             NVME_SC_FC_xxx value upon failure. Note: this is NOT a
+ *             reflection of the NVME CQE completion status. Only the status
+ *             of the FCP operation at the NVME-FC level.
+ */
+struct nvmefc_fcp_req {
+	void			*cmdaddr;
+	void			*rspaddr;
+	dma_addr_t		cmddma;
+	dma_addr_t		rspdma;
+	u16			cmdlen;
+	u16			rsplen;
+
+	u32			payload_length;
+	struct sg_table		sg_table;
+	struct scatterlist	*first_sgl;
+	int			sg_cnt;
+	enum nvmefc_fcp_datadir	io_dir;
+
+	__le16			sqid;
+
+	void (*done)(struct nvmefc_fcp_req *req);
+
+	void			*private;
+
+	u32			transferred_length;
+	u16			rcv_rsplen;
+	u32			status;
+} __aligned(sizeof(u64));	/* alignment for other things alloc'd with */
+
+
+/*
+ * Direct copy of fc_port_state enum. For later merging
+ */
+enum nvme_fc_obj_state {
+	FC_OBJSTATE_UNKNOWN,
+	FC_OBJSTATE_NOTPRESENT,
+	FC_OBJSTATE_ONLINE,
+	FC_OBJSTATE_OFFLINE,		/* User has taken Port Offline */
+	FC_OBJSTATE_BLOCKED,
+	FC_OBJSTATE_BYPASSED,
+	FC_OBJSTATE_DIAGNOSTICS,
+	FC_OBJSTATE_LINKDOWN,
+	FC_OBJSTATE_ERROR,
+	FC_OBJSTATE_LOOPBACK,
+	FC_OBJSTATE_DELETED,
+};
+
+
+/**
+ * struct nvme_fc_local_port - structure used between NVME-FC transport and
+ *                 a LLDD to reference a local NVME host port.
+ *                 Allocated/created by the nvme_fc_register_localport()
+ *                 transport interface.
+ *
+ * Fields with static values for the port. Initialized by the
+ * port_info struct supplied to the registration call.
+ * @port_num:  NVME-FC transport host port number
+ * @port_role: NVME roles are supported on the port (see FC_PORT_ROLE_xxx)
+ * @node_name: FC WWNN for the port
+ * @port_name: FC WWPN for the port
+ * @private:   pointer to memory allocated alongside the local port
+ *             structure that is specifically for the LLDD to use.
+ *             The length of the buffer corresponds to the local_priv_sz
+ *             value specified in the nvme_fc_port_template supplied by
+ *             the LLDD.
+ *
+ * Fields with dynamic values. Values may change base on link state. LLDD
+ * may reference fields directly to change them. Initialized by the
+ * port_info struct supplied to the registration call.
+ * @port_id:      FC N_Port_ID currently assigned the port. Upper 8 bits must
+ *                be set to 0.
+ * @port_state:   Operational state of the port.
+ */
+struct nvme_fc_local_port {
+	/* static/read-only fields */
+	u32 port_num;
+	u32 port_role;
+	u64 node_name;
+	u64 port_name;
+
+	void *private;
+
+	/* dynamic fields */
+	u32 port_id;
+	enum nvme_fc_obj_state port_state;
+} __aligned(sizeof(u64));	/* alignment for other things alloc'd with */
+
+
+/**
+ * struct nvme_fc_remote_port - structure used between NVME-FC transport and
+ *                 a LLDD to reference a remote NVME subsystem port.
+ *                 Allocated/created by the nvme_fc_register_remoteport()
+ *                 transport interface.
+ *
+ * Fields with static values for the port. Initialized by the
+ * port_info struct supplied to the registration call.
+ * @port_num:  NVME-FC transport remote subsystem port number
+ * @port_role: NVME roles are supported on the port (see FC_PORT_ROLE_xxx)
+ * @node_name: FC WWNN for the port
+ * @port_name: FC WWPN for the port
+ * @localport: pointer to the NVME-FC local host port the subsystem is
+ *             connected to.
+ * @private:   pointer to memory allocated alongside the remote port
+ *             structure that is specifically for the LLDD to use.
+ *             The length of the buffer corresponds to the remote_priv_sz
+ *             value specified in the nvme_fc_port_template supplied by
+ *             the LLDD.
+ *
+ * Fields with dynamic values. Values may change base on link or login
+ * state. LLDD may reference fields directly to change them. Initialized by
+ * the port_info struct supplied to the registration call.
+ * @port_id:      FC N_Port_ID currently assigned the port. Upper 8 bits must
+ *                be set to 0.
+ * @port_state:   Operational state of the remote port. Valid values are
+ *                ONLINE or UNKNOWN.
+ */
+struct nvme_fc_remote_port {
+	/* static fields */
+	u32 port_num;
+	u32 port_role;
+	u64 node_name;
+	u64 port_name;
+
+	struct nvme_fc_local_port *localport;
+
+	void *private;
+
+	/* dynamic fields */
+	u32 port_id;
+	enum nvme_fc_obj_state port_state;
+} __aligned(sizeof(u64));	/* alignment for other things alloc'd with */
+
+
+/**
+ * struct nvme_fc_port_template - structure containing static entrypoints and
+ *                 operational parameters for an LLDD that supports NVME host
+ *                 behavior. Passed by reference in port registrations.
+ *                 NVME-FC transport remembers template reference and may
+ *                 access it during runtime operation.
+ *
+ * Host/Initiator Transport Entrypoints/Parameters:
+ *
+ * @localport_delete:  The LLDD initiates deletion of a localport via
+ *       nvme_fc_deregister_localport(). However, the teardown is
+ *       asynchronous. This routine is called upon the completion of the
+ *       teardown to inform the LLDD that the localport has been deleted.
+ *       Entrypoint is Mandatory.
+ *
+ * @remoteport_delete:  The LLDD initiates deletion of a remoteport via
+ *       nvme_fc_deregister_remoteport(). However, the teardown is
+ *       asynchronous. This routine is called upon the completion of the
+ *       teardown to inform the LLDD that the remoteport has been deleted.
+ *       Entrypoint is Mandatory.
+ *
+ * @create_queue:  Upon creating a host<->controller association, queues are
+ *       created such that they can be affinitized to cpus/cores. This
+ *       callback into the LLDD to notify that a controller queue is being
+ *       created.  The LLDD may choose to allocate an associated hw queue
+ *       or map it onto a shared hw queue. Upon return from the call, the
+ *       LLDD specifies a handle that will be given back to it for any
+ *       command that is posted to the controller queue.  The handle can
+ *       be used by the LLDD to map quickly to the proper hw queue for
+ *       command execution.  The mask of cpu's that will map to this queue
+ *       at the block-level is also passed in. The LLDD should use the
+ *       queue id and/or cpu masks to ensure proper affinitization of the
+ *       controller queue to the hw queue.
+ *       Entrypoint is Optional.
+ *
+ * @delete_queue:  This is the inverse of the crete_queue. During
+ *       host<->controller association teardown, this routine is called
+ *       when a controller queue is being terminated. Any association with
+ *       a hw queue should be termined. If there is a unique hw queue, the
+ *       hw queue should be torn down.
+ *       Entrypoint is Optional.
+ *
+ * @poll_queue:  Called to poll for the completion of an io on a blk queue.
+ *       Entrypoint is Optional.
+ *
+ * @ls_req:  Called to issue a FC-NVME FC-4 LS service request.
+ *       The nvme_fc_ls_req structure will fully describe the buffers for
+ *       the request payload and where to place the response payload. The
+ *       LLDD is to allocate an exchange, issue the LS request, obtain the
+ *       LS response, and call the "done" routine specified in the request
+ *       structure (argument to done is the ls request structure itself).
+ *       Entrypoint is Mandatory.
+ *
+ * @fcp_io:  called to issue a FC-NVME I/O request.  The I/O may be for
+ *       an admin queue or an i/o queue.  The nvmefc_fcp_req structure will
+ *       fully describe the io: the buffer containing the FC-NVME CMD IU
+ *       (which contains the SQE), the sg list for the payload if applicable,
+ *       and the buffer to place the FC-NVME RSP IU into.  The LLDD will
+ *       complete the i/o, indicating the amount of data transferred or
+ *       any transport error, and call the "done" routine specified in the
+ *       request structure (argument to done is the fcp request structure
+ *       itself).
+ *       Entrypoint is Mandatory.
+ *
+ * @ls_abort: called to request the LLDD to abort the indicated ls request.
+ *       The call may return before the abort has completed. After aborting
+ *       the request, the LLDD must still call the ls request done routine
+ *       indicating an FC transport Aborted status.
+ *       Entrypoint is Mandatory.
+ *
+ * @fcp_abort: called to request the LLDD to abort the indicated fcp request.
+ *       The call may return before the abort has completed. After aborting
+ *       the request, the LLDD must still call the fcp request done routine
+ *       indicating an FC transport Aborted status.
+ *       Entrypoint is Mandatory.
+ *
+ * @max_hw_queues:  indicates the maximum number of hw queues the LLDD
+ *       supports for cpu affinitization.
+ *       Value is Mandatory. Must be at least 1.
+ *
+ * @max_sgl_segments:  indicates the maximum number of sgl segments supported
+ *       by the LLDD
+ *       Value is Mandatory. Must be at least 1. Recommend at least 256.
+ *
+ * @max_dif_sgl_segments:  indicates the maximum number of sgl segments
+ *       supported by the LLDD for DIF operations.
+ *       Value is Mandatory. Must be at least 1. Recommend at least 256.
+ *
+ * @dma_boundary:  indicates the dma address boundary where dma mappings
+ *       will be split across.
+ *       Value is Mandatory. Typical value is 0xFFFFFFFF to split across
+ *       4Gig address boundarys
+ *
+ * @local_priv_sz: The LLDD sets this field to the amount of additional
+ *       memory that it would like fc nvme layer to allocate on the LLDD's
+ *       behalf whenever a localport is allocated.  The additional memory
+ *       area solely for the of the LLDD and its location is specified by
+ *       the localport->private pointer.
+ *       Value is Mandatory. Allowed to be zero.
+ *
+ * @remote_priv_sz: The LLDD sets this field to the amount of additional
+ *       memory that it would like fc nvme layer to allocate on the LLDD's
+ *       behalf whenever a remoteport is allocated.  The additional memory
+ *       area solely for the of the LLDD and its location is specified by
+ *       the remoteport->private pointer.
+ *       Value is Mandatory. Allowed to be zero.
+ *
+ * @lsrqst_priv_sz: The LLDD sets this field to the amount of additional
+ *       memory that it would like fc nvme layer to allocate on the LLDD's
+ *       behalf whenever a ls request structure is allocated. The additional
+ *       memory area solely for the of the LLDD and its location is
+ *       specified by the ls_request->private pointer.
+ *       Value is Mandatory. Allowed to be zero.
+ *
+ * @fcprqst_priv_sz: The LLDD sets this field to the amount of additional
+ *       memory that it would like fc nvme layer to allocate on the LLDD's
+ *       behalf whenever a fcp request structure is allocated. The additional
+ *       memory area solely for the of the LLDD and its location is
+ *       specified by the fcp_request->private pointer.
+ *       Value is Mandatory. Allowed to be zero.
+ */
+struct nvme_fc_port_template {
+	/* initiator-based functions */
+	void	(*localport_delete)(struct nvme_fc_local_port *);
+	void	(*remoteport_delete)(struct nvme_fc_remote_port *);
+	int	(*create_queue)(struct nvme_fc_local_port *,
+				unsigned int qidx, u16 qsize,
+				void **handle);
+	void	(*delete_queue)(struct nvme_fc_local_port *,
+				unsigned int qidx, void *handle);
+	void	(*poll_queue)(struct nvme_fc_local_port *, void *handle);
+	int	(*ls_req)(struct nvme_fc_local_port *,
+				struct nvme_fc_remote_port *,
+				struct nvmefc_ls_req *);
+	int	(*fcp_io)(struct nvme_fc_local_port *,
+				struct nvme_fc_remote_port *,
+				void *hw_queue_handle,
+				struct nvmefc_fcp_req *);
+	void	(*ls_abort)(struct nvme_fc_local_port *,
+				struct nvme_fc_remote_port *,
+				struct nvmefc_ls_req *);
+	void	(*fcp_abort)(struct nvme_fc_local_port *,
+				struct nvme_fc_remote_port *,
+				void *hw_queue_handle,
+				struct nvmefc_fcp_req *);
+
+	u32	max_hw_queues;
+	u16	max_sgl_segments;
+	u16	max_dif_sgl_segments;
+	u64	dma_boundary;
+
+	/* sizes of additional private data for data structures */
+	u32	local_priv_sz;
+	u32	remote_priv_sz;
+	u32	lsrqst_priv_sz;
+	u32	fcprqst_priv_sz;
+};
+
+
+/*
+ * Initiator/Host functions
+ */
+
+int nvme_fc_register_localport(struct nvme_fc_port_info *pinfo,
+			struct nvme_fc_port_template *template,
+			struct device *dev,
+			struct nvme_fc_local_port **lport_p);
+
+int nvme_fc_unregister_localport(struct nvme_fc_local_port *localport);
+
+int nvme_fc_register_remoteport(struct nvme_fc_local_port *localport,
+			struct nvme_fc_port_info *pinfo,
+			struct nvme_fc_remote_port **rport_p);
+
+int nvme_fc_unregister_remoteport(struct nvme_fc_remote_port *remoteport);
+
+
+
+/*
+ * ***************  LLDD FC-NVME Target/Subsystem API ***************
+ *
+ *  For FC LLDD's that are the NVME Subsystem role
+ *
+ * ******************************************************************
+ */
+
+/**
+ * struct nvmet_fc_port_info - port-specific ids and FC connection-specific
+ *                             data element used during NVME Subsystem role
+ *                             registrations
+ *
+ * Static fields describing the port being registered:
+ * @node_name: FC WWNN for the port
+ * @port_name: FC WWPN for the port
+ *
+ * Initialization values for dynamic port fields:
+ * @port_id:      FC N_Port_ID currently assigned the port. Upper 8 bits must
+ *                be set to 0.
+ */
+struct nvmet_fc_port_info {
+	u64			node_name;
+	u64			port_name;
+	u32			port_id;
+};
+
+
+/**
+ * struct nvmefc_tgt_ls_req - Structure used between LLDD and NVMET-FC
+ *                            layer to represent the exchange context for
+ *                            a FC-NVME Link Service (LS).
+ *
+ * The structure is allocated by the LLDD whenever a LS Request is received
+ * from the FC link. The address of the structure is passed to the nvmet-fc
+ * layer via the nvmet_fc_rcv_ls_req() call. The address of the structure
+ * will be passed back to the LLDD when the response is to be transmit.
+ * The LLDD is to use the address to map back to the LLDD exchange structure
+ * which maintains information such as the targetport the LS was received
+ * on, the remote FC NVME initiator that sent the LS, and any FC exchange
+ * context.  Upon completion of the LS response transmit, the address of the
+ * structure will be passed back to the LS rsp done() routine, allowing the
+ * nvmet-fc layer to release dma resources. Upon completion of the done()
+ * routine, no further access will be made by the nvmet-fc layer and the
+ * LLDD can de-allocate the structure.
+ *
+ * Field initialization:
+ *   At the time of the nvmet_fc_rcv_ls_req() call, there is no content that
+ *     is valid in the structure.
+ *
+ *   When the structure is used for the LLDD->xmt_ls_rsp() call, the nvmet-fc
+ *     layer will fully set the fields in order to specify the response
+ *     payload buffer and its length as well as the done routine to be called
+ *     upon compeletion of the transmit.  The nvmet-fc layer will also set a
+ *     private pointer for its own use in the done routine.
+ *
+ * Values set by the NVMET-FC layer prior to calling the LLDD xmt_ls_rsp
+ * entrypoint.
+ * @rspbuf:   pointer to the LS response buffer
+ * @rspdma:   PCI DMA address of the LS response buffer
+ * @rsplen:   Length, in bytes, of the LS response buffer
+ * @done:     The callback routine the LLDD is to invoke upon completion of
+ *            transmitting the LS response. req argument is the pointer to
+ *            the original ls request.
+ * @nvmet_fc_private:  pointer to an internal NVMET-FC layer structure used
+ *            as part of the NVMET-FC processing. The LLDD is not to access
+ *            this pointer.
+ */
+struct nvmefc_tgt_ls_req {
+	void		*rspbuf;
+	dma_addr_t	rspdma;
+	u16		rsplen;
+
+	void (*done)(struct nvmefc_tgt_ls_req *req);
+	void *nvmet_fc_private;		/* LLDD is not to access !! */
+};
+
+/* Operations that NVME-FC layer may request the LLDD to perform for FCP */
+enum {
+	NVMET_FCOP_READDATA	= 1,	/* xmt data to initiator */
+	NVMET_FCOP_WRITEDATA	= 2,	/* xmt data from initiator */
+	NVMET_FCOP_READDATA_RSP	= 3,	/* xmt data to initiator and send
+					 * rsp as well
+					 */
+	NVMET_FCOP_RSP		= 4,	/* send rsp frame */
+	NVMET_FCOP_ABORT	= 5,	/* abort exchange via ABTS */
+	NVMET_FCOP_BA_ACC	= 6,	/* send BA_ACC */
+	NVMET_FCOP_BA_RJT	= 7,	/* send BA_RJT */
+};
+
+/**
+ * struct nvmefc_tgt_fcp_req - Structure used between LLDD and NVMET-FC
+ *                            layer to represent the exchange context and
+ *                            the specific FC-NVME IU operation(s) to perform
+ *                            for a FC-NVME FCP IO.
+ *
+ * Structure used between LLDD and nvmet-fc layer to represent the exchange
+ * context for a FC-NVME FCP I/O operation (e.g. a nvme sqe, the sqe-related
+ * memory transfers, and its assocated cqe transfer).
+ *
+ * The structure is allocated by the LLDD whenever a FCP CMD IU is received
+ * from the FC link. The address of the structure is passed to the nvmet-fc
+ * layer via the nvmet_fc_rcv_fcp_req() call. The address of the structure
+ * will be passed back to the LLDD for the data operations and transmit of
+ * the response. The LLDD is to use the address to map back to the LLDD
+ * exchange structure which maintains information such as the targetport
+ * the FCP I/O was received on, the remote FC NVME initiator that sent the
+ * FCP I/O, and any FC exchange context.  Upon completion of the FCP target
+ * operation, the address of the structure will be passed back to the FCP
+ * op done() routine, allowing the nvmet-fc layer to release dma resources.
+ * Upon completion of the done() routine for either RSP or ABORT ops, no
+ * further access will be made by the nvmet-fc layer and the LLDD can
+ * de-allocate the structure.
+ *
+ * Field initialization:
+ *   At the time of the nvmet_fc_rcv_fcp_req() call, there is no content that
+ *     is valid in the structure.
+ *
+ *   When the structure is used for an FCP target operation, the nvmet-fc
+ *     layer will fully set the fields in order to specify the scattergather
+ *     list, the transfer length, as well as the done routine to be called
+ *     upon compeletion of the operation.  The nvmet-fc layer will also set a
+ *     private pointer for its own use in the done routine.
+ *
+ * Note: the LLDD must never fail a NVMET_FCOP_ABORT request !!
+ *
+ * Values set by the NVMET-FC layer prior to calling the LLDD fcp_op
+ * entrypoint.
+ * @op:       Indicates the FCP IU operation to perform (see NVMET_FCOP_xxx)
+ * @hwqid:    Specifies the hw queue index (0..N-1, where N is the
+ *            max_hw_queues value from the LLD's nvmet_fc_target_template)
+ *            that the operation is to use.
+ * @offset:   Indicates the DATA_OUT/DATA_IN payload offset to be tranferred.
+ *            Field is only valid on WRITEDATA, READDATA, or READDATA_RSP ops.
+ * @timeout:  amount of time, in seconds, to wait for a response from the NVME
+ *            host. A value of 0 is an infinite wait.
+ *            Valid only for the following ops:
+ *              WRITEDATA: caps the wait for data reception
+ *              READDATA_RSP & RSP: caps wait for FCP_CONF reception (if used)
+ * @transfer_length: the length, in bytes, of the DATA_OUT or DATA_IN payload
+ *            that is to be transferred.
+ *            Valid only for the WRITEDATA, READDATA, or READDATA_RSP ops.
+ * @ba_rjt:   Contains the BA_RJT payload that is to be transferred.
+ *            Valid only for the NVMET_FCOP_BA_RJT op.
+ * @sg:       Scatter/gather list for the DATA_OUT/DATA_IN payload data.
+ *            Valid only for the WRITEDATA, READDATA, or READDATA_RSP ops.
+ * @sg_cnt:   Number of valid entries in the scatter/gather list.
+ *            Valid only for the WRITEDATA, READDATA, or READDATA_RSP ops.
+ * @rspaddr:  pointer to the FCP RSP IU buffer to be transmit
+ *            Used by RSP and READDATA_RSP ops
+ * @rspdma:   PCI DMA address of the FCP RSP IU buffer
+ *            Used by RSP and READDATA_RSP ops
+ * @rsplen:   Length, in bytes, of the FCP RSP IU buffer
+ *            Used by RSP and READDATA_RSP ops
+ * @done:     The callback routine the LLDD is to invoke upon completion of
+ *            the operation. req argument is the pointer to the original
+ *            FCP subsystem op request.
+ * @nvmet_fc_private:  pointer to an internal NVMET-FC layer structure used
+ *            as part of the NVMET-FC processing. The LLDD is not to
+ *            reference this field.
+ *
+ * Values set by the LLDD indicating completion status of the FCP operation.
+ * Must be set prior to calling the done() callback.
+ * @transferred_length: amount of DATA_OUT payload data received by a
+ *            a WRITEDATA operation. If not a WRITEDATA operation, value must
+ *            be set to 0. Should equal transfer_length on success.
+ * @fcp_error: status of the FCP operation. Must be 0 on success; on failure
+ *            must be a NVME_SC_FC_xxxx value.
+ */
+struct nvmefc_tgt_fcp_req {
+	u8			op;
+	u16			hwqid;
+	u32			offset;
+	u32			timeout;
+	u32			transfer_length;
+	struct fc_ba_rjt	ba_rjt;
+	struct scatterlist	sg[NVME_FC_MAX_SEGMENTS];
+	int			sg_cnt;
+	void			*rspaddr;
+	dma_addr_t		rspdma;
+	u16			rsplen;
+
+	void (*done)(struct nvmefc_tgt_fcp_req *);
+
+	void *nvmet_fc_private;		/* LLDD is not to access !! */
+
+	u32			transferred_length;
+	int			fcp_error;
+};
+
+
+/* Target Features (Bit fields) LLDD supports */
+enum {
+	NVMET_FCTGTFEAT_READDATA_RSP = (1 << 0),
+		/* Bit 0: supports the NVMET_FCPOP_READDATA_RSP op, which
+		 * sends (the last) Read Data sequence followed by the RSP
+		 * sequence in one LLDD operation. Errors during Data
+		 * sequence transmit must not allow RSP sequence to be sent.
+		 */
+	NVMET_FCTGTFEAT_NEEDS_CMD_CPUSCHED = (1 << 1),
+		/* Bit 1: When 0, the LLDD will deliver FCP CMD
+		 * on the CPU it should be affinitized to. Thus work will
+		 * be scheduled on the cpu received on. When 1, the LLDD
+		 * may not deliver the CMD on the CPU it should be worked
+		 * on. The transport should pick a cpu to schedule the work
+		 * on.
+		 */
+};
+
+
+/**
+ * struct nvmet_fc_target_port - structure used between NVME-FC transport and
+ *                 a LLDD to reference a local NVME subsystem port.
+ *                 Allocated/created by the nvme_fc_register_targetport()
+ *                 transport interface.
+ *
+ * Fields with static values for the port. Initialized by the
+ * port_info struct supplied to the registration call.
+ * @port_num:  NVME-FC transport subsytem port number
+ * @node_name: FC WWNN for the port
+ * @port_name: FC WWPN for the port
+ * @private:   pointer to memory allocated alongside the local port
+ *             structure that is specifically for the LLDD to use.
+ *             The length of the buffer corresponds to the target_priv_sz
+ *             value specified in the nvme_fc_target_template supplied by
+ *             the LLDD.
+ *
+ * Fields with dynamic values. Values may change base on link state. LLDD
+ * may reference fields directly to change them. Initialized by the
+ * port_info struct supplied to the registration call.
+ * @port_id:      FC N_Port_ID currently assigned the port. Upper 8 bits must
+ *                be set to 0.
+ * @port_state:   Operational state of the port.
+ */
+struct nvmet_fc_target_port {
+	/* static/read-only fields */
+	u32 port_num;
+	u64 node_name;
+	u64 port_name;
+
+	void *private;
+
+	/* dynamic fields */
+	u32 port_id;
+	enum nvme_fc_obj_state port_state;
+} __aligned(sizeof(u64));	/* alignment for other things alloc'd with */
+
+
+/**
+ * struct nvmet_fc_target_template - structure containing static entrypoints
+ *                 and operational parameters for an LLDD that supports NVME
+ *                 subsystem behavior. Passed by reference in port
+ *                 registrations. NVME-FC transport remembers template
+ *                 reference and may access it during runtime operation.
+ *
+ * Subsystem/Target Transport Entrypoints/Parameters:
+ *
+ * @targetport_delete:  The LLDD initiates deletion of a targetport via
+ *       nvmet_fc_unregister_targetport(). However, the teardown is
+ *       asynchronous. This routine is called upon the completion of the
+ *       teardown to inform the LLDD that the targetport has been deleted.
+ *       Entrypoint is Mandatory.
+ *
+ * @xmt_ls_rsp:  Called to transmit the response to a FC-NVME FC-4 LS service.
+ *       The nvmefc_tgt_ls_req structure is the same LLDD-supplied exchange
+ *       structure specified in the nvmet_fc_rcv_ls_req() call made when
+ *       the LS request was received.  The structure will fully describe
+ *       the buffers for the response payload and the dma address of the
+ *       payload. The LLDD is to transmit the response (or return a non-zero
+ *       errno status), and upon completion of the transmit, call the
+ *       "done" routine specified in the nvmefc_tgt_ls_req structure
+ *       (argument to done is the ls reqwuest structure itself).
+ *       After calling the done routine, the LLDD shall consider the
+ *       LS handling complete and the nvmefc_tgt_ls_req structure may
+ *       be freed/released.
+ *       Entrypoint is Mandatory.
+ *
+ * @fcp_op:  Called to perform a data transfer, transmit a response, or
+ *       abort an FCP opertion. The nvmefc_tgt_fcp_req structure is the same
+ *       LLDD-supplied exchange structure specified in the
+ *       nvmet_fc_rcv_fcp_req() call made when the FCP CMD IU was received.
+ *       The op field in the structure shall indicate the operation for
+ *       the LLDD to perform relative to the io.
+ *         NVMET_FCOP_READDATA operation: the LLDD is to send the
+ *           payload data (described by sglist) to the host in 1 or
+ *           more FC sequences (preferrably 1).  Note: the fc-nvme layer
+ *           may call the READDATA operation multiple times for longer
+ *           payloads.
+ *         NVMET_FCOP_WRITEDATA operation: the LLDD is to receive the
+ *           payload data (described by sglist) from the host via 1 or
+ *           more FC sequences (preferrably 1). The LLDD is to generate
+ *           the XFER_RDY IU(s) corresponding to the data being requested.
+ *           Note: the FC-NVME layer may call the WRITEDATA operation
+ *           multiple times for longer payloads.
+ *         NVMET_FCOP_READDATA_RSP operation: the LLDD is to send the
+ *           payload data (described by sglist) to the host in 1 or
+ *           more FC sequences (preferrably 1). If an error occurs during
+ *           payload data transmission, the LLDD is to set the
+ *           nvmefc_tgt_fcp_req fcp_error and transferred_length field, then
+ *           consider the operation complete. On error, the LLDD is to not
+ *           transmit the FCP_RSP iu. If all payload data is transferred
+ *           successfully, the LLDD is to update the nvmefc_tgt_fcp_req
+ *           transferred_length field and may subsequently transmit the
+ *           FCP_RSP iu payload (described by rspbuf, rspdma, rsplen).
+ *           The LLDD is to await FCP_CONF reception to confirm the RSP
+ *           reception by the host. The LLDD may retramsit the FCP_RSP iu
+ *           if necessary per FC-NVME. Upon reception of FCP_CONF, or upon
+ *           FCP_CONF failure, the LLDD is to set the nvmefc_tgt_fcp_req
+ *           fcp_error field and consider the operation complete..
+ *         NVMET_FCOP_RSP: the LLDD is to transmit the FCP_RSP iu payload
+ *           (described by rspbuf, rspdma, rsplen).  The LLDD is to await
+ *           FCP_CONF reception to confirm the RSP reception by the host.
+ *           The LLDD may retramsit the FCP_RSP iu if necessary per FC-NVME.
+ *           Upon reception of FCP_CONF, or upon FCP_CONF failure, the
+ *           LLDD is to set the nvmefc_tgt_fcp_req fcp_error field and
+ *           consider the operation complete..
+ *         NVMET_FCOP_ABORT: the LLDD is to terminate the exchange
+ *           corresponding to the fcp operation. The LLDD shall send
+ *           ABTS and follow FC exchange abort-multi rules, including
+ *           ABTS retries and possible logout.
+ *       Upon completing the indicated operation, the LLDD is to set the
+ *       status fields for the operation (tranferred_length and fcp_error
+ *       status) in the request, then all the "done" routine
+ *       indicated in the fcp request.  Upon return from the "done"
+ *       routine for either a NVMET_FCOP_RSP or NVMET_FCOP_ABORT operation
+ *       the fc-nvme layer will not longer reference the fcp request,
+ *       allowing the LLDD to free/release the fcp request.
+ *       Note: when calling the done routine for READDATA or WRITEDATA
+ *       operations, the fc-nvme layer may immediate convert, in the same
+ *       thread and before returning to the LLDD, the fcp operation to
+ *       the next operation for the fcp io and call the LLDDs fcp_op
+ *       call again. If fields in the fcp request are to be accessed post
+ *       the done call, the LLDD should save their values prior to calling
+ *       the done routine, and inspect the save values after the done
+ *       routine.
+ *       Returns 0 on success, -<errno> on failure (Ex: -EIO)
+ *       Entrypoint is Mandatory.
+ *
+ * @max_hw_queues:  indicates the maximum number of hw queues the LLDD
+ *       supports for cpu affinitization.
+ *       Value is Mandatory. Must be at least 1.
+ *
+ * @max_sgl_segments:  indicates the maximum number of sgl segments supported
+ *       by the LLDD
+ *       Value is Mandatory. Must be at least 1. Recommend at least 256.
+ *
+ * @max_dif_sgl_segments:  indicates the maximum number of sgl segments
+ *       supported by the LLDD for DIF operations.
+ *       Value is Mandatory. Must be at least 1. Recommend at least 256.
+ *
+ * @dma_boundary:  indicates the dma address boundary where dma mappings
+ *       will be split across.
+ *       Value is Mandatory. Typical value is 0xFFFFFFFF to split across
+ *       4Gig address boundarys
+ *
+ * @target_features: The LLDD sets bits in this field to correspond to
+ *       optional features that are supported by the LLDD.
+ *       Refer to the NVMET_FCTGTFEAT_xxx values.
+ *       Value is Mandatory. Allowed to be zero.
+ *
+ * @target_priv_sz: The LLDD sets this field to the amount of additional
+ *       memory that it would like fc nvme layer to allocate on the LLDD's
+ *       behalf whenever a targetport is allocated.  The additional memory
+ *       area solely for the of the LLDD and its location is specified by
+ *       the targetport->private pointer.
+ *       Value is Mandatory. Allowed to be zero.
+ */
+struct nvmet_fc_target_template {
+	void (*targetport_delete)(struct nvmet_fc_target_port *tgtport);
+	int (*xmt_ls_rsp)(struct nvmet_fc_target_port *tgtport,
+				struct nvmefc_tgt_ls_req *tls_req);
+	int (*fcp_op)(struct nvmet_fc_target_port *tgtport,
+				struct nvmefc_tgt_fcp_req *);
+
+	u32	max_hw_queues;
+	u16	max_sgl_segments;
+	u16	max_dif_sgl_segments;
+	u64	dma_boundary;
+
+	u32	target_features;
+
+	u32	target_priv_sz;
+};
+
+
+int nvmet_fc_register_targetport(struct nvmet_fc_port_info *portinfo,
+			struct nvmet_fc_target_template *template,
+			struct device *dev,
+			struct nvmet_fc_target_port **tgtport_p);
+
+int nvmet_fc_unregister_targetport(struct nvmet_fc_target_port *tgtport);
+
+int nvmet_fc_rcv_ls_req(struct nvmet_fc_target_port *tgtport,
+			struct nvmefc_tgt_ls_req *lsreq,
+			void *lsreqbuf, u32 lsreqbuf_len);
+
+int nvmet_fc_rcv_fcp_req(struct nvmet_fc_target_port *tgtport,
+			struct nvmefc_tgt_fcp_req *fcpreq,
+			void *cmdiubuf, u32 cmdiubuf_len);
+
+#endif /* _NVME_FC_DRIVER_H */