[SCSI] cxgb3i: Add cxgb3i iSCSI driver.

This patch implements the cxgb3i iscsi connection acceleration for the
open-iscsi initiator.

The cxgb3i driver offers the iscsi PDU based offload:
- digest insertion and verification
- payload direct-placement into host memory buffer.

Signed-off-by: Karen Xie <[email protected]>
Signed-off-by: James Bottomley <[email protected]>

Documentation/scsi/cxgb3i.txt

@@ -0,0 +1,85 @@
+Chelsio S3 iSCSI Driver for Linux
+
+Introduction
+============
+
+The Chelsio T3 ASIC based Adapters (S310, S320, S302, S304, Mezz cards, etc.
+series of products) supports iSCSI acceleration and iSCSI Direct Data Placement
+(DDP) where the hardware handles the expensive byte touching operations, such
+as CRC computation and verification, and direct DMA to the final host memory
+destination:
+
+	- iSCSI PDU digest generation and verification
+
+	  On transmitting, Chelsio S3 h/w computes and inserts the Header and
+	  Data digest into the PDUs.
+	  On receiving, Chelsio S3 h/w computes and verifies the Header and
+	  Data digest of the PDUs.
+
+	- Direct Data Placement (DDP)
+
+	  S3 h/w can directly place the iSCSI Data-In or Data-Out PDU's
+	  payload into pre-posted final destination host-memory buffers based
+	  on the Initiator Task Tag (ITT) in Data-In or Target Task Tag (TTT)
+	  in Data-Out PDUs.
+
+	- PDU Transmit and Recovery
+
+	  On transmitting, S3 h/w accepts the complete PDU (header + data)
+	  from the host driver, computes and inserts the digests, decomposes
+	  the PDU into multiple TCP segments if necessary, and transmit all
+	  the TCP segments onto the wire. It handles TCP retransmission if
+	  needed.
+
+	  On receving, S3 h/w recovers the iSCSI PDU by reassembling TCP
+	  segments, separating the header and data, calculating and verifying
+	  the digests, then forwards the header to the host. The payload data,
+	  if possible, will be directly placed into the pre-posted host DDP
+	  buffer. Otherwise, the payload data will be sent to the host too.
+
+The cxgb3i driver interfaces with open-iscsi initiator and provides the iSCSI
+acceleration through Chelsio hardware wherever applicable.
+
+Using the cxgb3i Driver
+=======================
+
+The following steps need to be taken to accelerates the open-iscsi initiator:
+
+1. Load the cxgb3i driver: "modprobe cxgb3i"
+
+   The cxgb3i module registers a new transport class "cxgb3i" with open-iscsi.
+
+   * in the case of recompiling the kernel, the cxgb3i selection is located at
+	Device Drivers
+		SCSI device support --->
+			[*] SCSI low-level drivers  --->
+				<M>   Chelsio S3xx iSCSI support
+
+2. Create an interface file located under /etc/iscsi/ifaces/ for the new
+   transport class "cxgb3i".
+
+   The content of the file should be in the following format:
+	iface.transport_name = cxgb3i
+	iface.net_ifacename = <ethX>
+	iface.ipaddress = <iscsi ip address>
+
+   * if iface.ipaddress is specified, <iscsi ip address> needs to be either the
+	same as the ethX's ip address or an address on the same subnet. Make
+	sure the ip address is unique in the network.
+
+3. edit /etc/iscsi/iscsid.conf
+   The default setting for MaxRecvDataSegmentLength (131072) is too big,
+   replace "node.conn[0].iscsi.MaxRecvDataSegmentLength" to be a value no
+   bigger than 15360 (for example 8192):
+
+	node.conn[0].iscsi.MaxRecvDataSegmentLength = 8192
+
+   * The login would fail for a normal session if MaxRecvDataSegmentLength is
+	too big.  A error message in the format of
+	"cxgb3i: ERR! MaxRecvSegmentLength <X> too big. Need to be <= <Y>."
+	would be logged to dmesg.
+
+4. To direct open-iscsi traffic to go through cxgb3i's accelerated path,
+   "-I <iface file name>" option needs to be specified with most of the
+   iscsiadm command. <iface file name> is the transport interface file created
+   in step 2.

drivers/scsi/Kconfig

@@ -352,6 +352,8 @@ config ISCSI_TCP
 
 	 http://open-iscsi.org
 
+source "drivers/scsi/cxgb3i/Kconfig"
+
 config SGIWD93_SCSI
 	tristate "SGI WD93C93 SCSI Driver"
 	depends on SGI_HAS_WD93 && SCSI

drivers/scsi/Makefile

@@ -126,6 +126,7 @@ obj-$(CONFIG_SCSI_HPTIOP)	+= hptiop.o
 obj-$(CONFIG_SCSI_STEX)		+= stex.o
 obj-$(CONFIG_SCSI_MVSAS)	+= mvsas.o
 obj-$(CONFIG_PS3_ROM)		+= ps3rom.o
+obj-$(CONFIG_SCSI_CXGB3_ISCSI)	+= libiscsi.o libiscsi_tcp.o cxgb3i/
 
 obj-$(CONFIG_ARM)		+= arm/
 

drivers/scsi/cxgb3i/Kbuild

@@ -0,0 +1,4 @@
+EXTRA_CFLAGS += -I$(TOPDIR)/drivers/net/cxgb3
+
+cxgb3i-y := cxgb3i_init.o cxgb3i_iscsi.o cxgb3i_pdu.o cxgb3i_offload.o
+obj-$(CONFIG_SCSI_CXGB3_ISCSI) += cxgb3i_ddp.o cxgb3i.o

drivers/scsi/cxgb3i/Kconfig

@@ -0,0 +1,6 @@
+config SCSI_CXGB3_ISCSI
+	tristate "Chelsio S3xx iSCSI support"
+	select CHELSIO_T3
+	select SCSI_ISCSI_ATTRS
+	---help---
+	This driver supports iSCSI offload for the Chelsio S3 series devices.

drivers/scsi/cxgb3i/cxgb3i.h

@@ -0,0 +1,139 @@
+/*
+ * cxgb3i.h: Chelsio S3xx iSCSI driver.
+ *
+ * Copyright (c) 2008 Chelsio Communications, Inc.
+ *
+ * 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.
+ *
+ * Written by: Karen Xie ([email protected])
+ */
+
+#ifndef __CXGB3I_H__
+#define __CXGB3I_H__
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/list.h>
+#include <linux/netdevice.h>
+#include <linux/scatterlist.h>
+#include <scsi/libiscsi_tcp.h>
+
+/* from cxgb3 LLD */
+#include "common.h"
+#include "t3_cpl.h"
+#include "t3cdev.h"
+#include "cxgb3_ctl_defs.h"
+#include "cxgb3_offload.h"
+#include "firmware_exports.h"
+
+#include "cxgb3i_offload.h"
+#include "cxgb3i_ddp.h"
+
+#define CXGB3I_SCSI_QDEPTH_DFLT	128
+#define CXGB3I_MAX_TARGET	CXGB3I_MAX_CONN
+#define CXGB3I_MAX_LUN		512
+#define ISCSI_PDU_NONPAYLOAD_MAX \
+	(sizeof(struct iscsi_hdr) + ISCSI_MAX_AHS_SIZE + 2*ISCSI_DIGEST_SIZE)
+
+struct cxgb3i_adapter;
+struct cxgb3i_hba;
+struct cxgb3i_endpoint;
+
+/**
+ * struct cxgb3i_hba - cxgb3i iscsi structure (per port)
+ *
+ * @snic:	cxgb3i adapter containing this port
+ * @ndev:	pointer to netdev structure
+ * @shost:	pointer to scsi host structure
+ */
+struct cxgb3i_hba {
+	struct cxgb3i_adapter *snic;
+	struct net_device *ndev;
+	struct Scsi_Host *shost;
+};
+
+/**
+ * struct cxgb3i_adapter - cxgb3i adapter structure (per pci)
+ *
+ * @listhead:	list head to link elements
+ * @lock:	lock for this structure
+ * @tdev:	pointer to t3cdev used by cxgb3 driver
+ * @pdev:	pointer to pci dev
+ * @hba_cnt:	# of hbas (the same as # of ports)
+ * @hba:	all the hbas on this adapter
+ * @tx_max_size: max. tx packet size supported
+ * @rx_max_size: max. rx packet size supported
+ * @tag_format: ddp tag format settings
+ */
+struct cxgb3i_adapter {
+	struct list_head list_head;
+	spinlock_t lock;
+	struct t3cdev *tdev;
+	struct pci_dev *pdev;
+	unsigned char hba_cnt;
+	struct cxgb3i_hba *hba[MAX_NPORTS];
+
+	unsigned int tx_max_size;
+	unsigned int rx_max_size;
+
+	struct cxgb3i_tag_format tag_format;
+};
+
+/**
+ * struct cxgb3i_conn - cxgb3i iscsi connection
+ *
+ * @listhead:	list head to link elements
+ * @cep:	pointer to iscsi_endpoint structure
+ * @conn:	pointer to iscsi_conn structure
+ * @hba:	pointer to the hba this conn. is going through
+ * @task_idx_bits: # of bits needed for session->cmds_max
+ */
+struct cxgb3i_conn {
+	struct list_head list_head;
+	struct cxgb3i_endpoint *cep;
+	struct iscsi_conn *conn;
+	struct cxgb3i_hba *hba;
+	unsigned int task_idx_bits;
+};
+
+/**
+ * struct cxgb3i_endpoint - iscsi tcp endpoint
+ *
+ * @c3cn:	the h/w tcp connection representation
+ * @hba:	pointer to the hba this conn. is going through
+ * @cconn:	pointer to the associated cxgb3i iscsi connection
+ */
+struct cxgb3i_endpoint {
+	struct s3_conn *c3cn;
+	struct cxgb3i_hba *hba;
+	struct cxgb3i_conn *cconn;
+};
+
+int cxgb3i_iscsi_init(void);
+void cxgb3i_iscsi_cleanup(void);
+
+struct cxgb3i_adapter *cxgb3i_adapter_add(struct t3cdev *);
+void cxgb3i_adapter_remove(struct t3cdev *);
+int cxgb3i_adapter_ulp_init(struct cxgb3i_adapter *);
+void cxgb3i_adapter_ulp_cleanup(struct cxgb3i_adapter *);
+
+struct cxgb3i_hba *cxgb3i_hba_find_by_netdev(struct net_device *);
+struct cxgb3i_hba *cxgb3i_hba_host_add(struct cxgb3i_adapter *,
+				       struct net_device *);
+void cxgb3i_hba_host_remove(struct cxgb3i_hba *);
+
+int cxgb3i_pdu_init(void);
+void cxgb3i_pdu_cleanup(void);
+void cxgb3i_conn_cleanup_task(struct iscsi_task *);
+int cxgb3i_conn_alloc_pdu(struct iscsi_task *, u8);
+int cxgb3i_conn_init_pdu(struct iscsi_task *, unsigned int, unsigned int);
+int cxgb3i_conn_xmit_pdu(struct iscsi_task *);
+
+void cxgb3i_release_itt(struct iscsi_task *task, itt_t hdr_itt);
+int cxgb3i_reserve_itt(struct iscsi_task *task, itt_t *hdr_itt);
+
+#endif