ibmvscsis: Initial commit of IBM VSCSI Tgt Driver

This driver is a pick up of the old IBM VIO scsi Target Driver
that was started by Nick and Fujita 2-4 years ago.
http://comments.gmane.org/gmane.linux.scsi/90119

The driver provides a virtual SCSI device on IBM Power Servers.

This patch contains the fifth version for an initial merge of the
tcm ibmvscsis driver. More information on this driver and config
can be found:

https://github.com/powervm/ibmvscsis/wiki/Configuration
http://www.linux-iscsi.org/wiki/IBM_vSCSI

(Drop extra libsrp review breakage + Fix kconfig typo - nab)

Signed-off-by: Steven Royer <seroyer@linux.vnet.ibm.com>
Signed-off-by: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
Signed-off-by: Michael Cyr <mikecyr@linux.vnet.ibm.com>
Signed-off-by: Bryant G. Ly <bryantly@linux.vnet.ibm.com>
Cc: FUJITA Tomonori <tomof@acm.org>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

5 files changed, 4986 insertions, 0 deletions

diff --git a/drivers/scsi/ibmvscsi_tgt/Makefile b/drivers/scsi/ibmvscsi_tgt/Makefile
new file mode 100644
index 000000000000..0c060ce64cb0
--- /dev/null
+++ b/drivers/scsi/ibmvscsi_tgt/Makefile
@@ -0,0 +1,3 @@
+obj-$(CONFIG_SCSI_IBMVSCSIS)	+= ibmvscsis.o
+
+ibmvscsis-y := libsrp.o ibmvscsi_tgt.o
diff --git a/drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c b/drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c
new file mode 100644
index 000000000000..b29fef9d0f27
--- /dev/null
+++ b/drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c
@@ -0,0 +1,4087 @@
+/*******************************************************************************
+ * IBM Virtual SCSI Target Driver
+ * Copyright (C) 2003-2005 Dave Boutcher (boutcher@us.ibm.com) IBM Corp.
+ *			   Santiago Leon (santil@us.ibm.com) IBM Corp.
+ *			   Linda Xie (lxie@us.ibm.com) IBM Corp.
+ *
+ * Copyright (C) 2005-2011 FUJITA Tomonori <tomof@acm.org>
+ * Copyright (C) 2010 Nicholas A. Bellinger <nab@kernel.org>
+ *
+ * Authors: Bryant G. Ly <bryantly@linux.vnet.ibm.com>
+ * Authors: Michael Cyr <mikecyr@linux.vnet.ibm.com>
+ *
+ * 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
+ * (at your option) 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.
+ *
+ ****************************************************************************/
+
+#define pr_fmt(fmt)     KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/list.h>
+#include <linux/string.h>
+
+#include <target/target_core_base.h>
+#include <target/target_core_fabric.h>
+
+#include <asm/hvcall.h>
+#include <asm/vio.h>
+
+#include <scsi/viosrp.h>
+
+#include "ibmvscsi_tgt.h"
+
+#define IBMVSCSIS_VERSION	"v0.2"
+
+#define	INITIAL_SRP_LIMIT	800
+#define	DEFAULT_MAX_SECTORS	256
+
+static uint max_vdma_size = MAX_H_COPY_RDMA;
+
+static char system_id[SYS_ID_NAME_LEN] = "";
+static char partition_name[PARTITION_NAMELEN] = "UNKNOWN";
+static uint partition_number = -1;
+
+/* Adapter list and lock to control it */
+static DEFINE_SPINLOCK(ibmvscsis_dev_lock);
+static LIST_HEAD(ibmvscsis_dev_list);
+
+static long ibmvscsis_parse_command(struct scsi_info *vscsi,
+				    struct viosrp_crq *crq);
+
+static void ibmvscsis_adapter_idle(struct scsi_info *vscsi);
+
+static void ibmvscsis_determine_resid(struct se_cmd *se_cmd,
+				      struct srp_rsp *rsp)
+{
+	u32 residual_count = se_cmd->residual_count;
+
+	if (!residual_count)
+		return;
+
+	if (se_cmd->se_cmd_flags & SCF_UNDERFLOW_BIT) {
+		if (se_cmd->data_direction == DMA_TO_DEVICE) {
+			/* residual data from an underflow write */
+			rsp->flags = SRP_RSP_FLAG_DOUNDER;
+			rsp->data_out_res_cnt = cpu_to_be32(residual_count);
+		} else if (se_cmd->data_direction == DMA_FROM_DEVICE) {
+			/* residual data from an underflow read */
+			rsp->flags = SRP_RSP_FLAG_DIUNDER;
+			rsp->data_in_res_cnt = cpu_to_be32(residual_count);
+		}
+	} else if (se_cmd->se_cmd_flags & SCF_OVERFLOW_BIT) {
+		if (se_cmd->data_direction == DMA_TO_DEVICE) {
+			/*  residual data from an overflow write */
+			rsp->flags = SRP_RSP_FLAG_DOOVER;
+			rsp->data_out_res_cnt = cpu_to_be32(residual_count);
+		} else if (se_cmd->data_direction == DMA_FROM_DEVICE) {
+			/* residual data from an overflow read */
+			rsp->flags = SRP_RSP_FLAG_DIOVER;
+			rsp->data_in_res_cnt = cpu_to_be32(residual_count);
+		}
+	}
+}
+
+/**
+ * connection_broken() - Determine if the connection to the client is good
+ * @vscsi:	Pointer to our adapter structure
+ *
+ * This function attempts to send a ping MAD to the client. If the call to
+ * queue the request returns H_CLOSED then the connection has been broken
+ * and the function returns TRUE.
+ *
+ * EXECUTION ENVIRONMENT:
+ *      Interrupt or Process environment
+ */
+static bool connection_broken(struct scsi_info *vscsi)
+{
+	struct viosrp_crq *crq;
+	u64 buffer[2] = { 0, 0 };
+	long h_return_code;
+	bool rc = false;
+
+	/* create a PING crq */
+	crq = (struct viosrp_crq *)&buffer;
+	crq->valid = VALID_CMD_RESP_EL;
+	crq->format = MESSAGE_IN_CRQ;
+	crq->status = PING;
+
+	h_return_code = h_send_crq(vscsi->dds.unit_id,
+				   cpu_to_be64(buffer[MSG_HI]),
+				   cpu_to_be64(buffer[MSG_LOW]));
+
+	pr_debug("connection_broken: rc %ld\n", h_return_code);
+
+	if (h_return_code == H_CLOSED)
+		rc = true;
+
+	return rc;
+}
+
+/**
+ * ibmvscsis_unregister_command_q() - Helper Function-Unregister Command Queue
+ * @vscsi:	Pointer to our adapter structure
+ *
+ * This function calls h_free_q then frees the interrupt bit etc.
+ * It must release the lock before doing so because of the time it can take
+ * for h_free_crq in PHYP
+ * NOTE: the caller must make sure that state and or flags will prevent
+ *	 interrupt handler from scheduling work.
+ * NOTE: anyone calling this function may need to set the CRQ_CLOSED flag
+ *	 we can't do it here, because we don't have the lock
+ *
+ * EXECUTION ENVIRONMENT:
+ *	Process level
+ */
+static long ibmvscsis_unregister_command_q(struct scsi_info *vscsi)
+{
+	long qrc;
+	long rc = ADAPT_SUCCESS;
+	int ticks = 0;
+
+	do {
+		qrc = h_free_crq(vscsi->dds.unit_id);
+		switch (qrc) {
+		case H_SUCCESS:
+			break;
+
+		case H_HARDWARE:
+		case H_PARAMETER:
+			dev_err(&vscsi->dev, "unregister_command_q: error from h_free_crq %ld\n",
+				qrc);
+			rc = ERROR;
+			break;
+
+		case H_BUSY:
+		case H_LONG_BUSY_ORDER_1_MSEC:
+			/* msleep not good for small values */
+			usleep_range(1000, 2000);
+			ticks += 1;
+			break;
+		case H_LONG_BUSY_ORDER_10_MSEC:
+			usleep_range(10000, 20000);
+			ticks += 10;
+			break;
+		case H_LONG_BUSY_ORDER_100_MSEC:
+			msleep(100);
+			ticks += 100;
+			break;
+		case H_LONG_BUSY_ORDER_1_SEC:
+			ssleep(1);
+			ticks += 1000;
+			break;
+		case H_LONG_BUSY_ORDER_10_SEC:
+			ssleep(10);
+			ticks += 10000;
+			break;
+		case H_LONG_BUSY_ORDER_100_SEC:
+			ssleep(100);
+			ticks += 100000;
+			break;
+		default:
+			dev_err(&vscsi->dev, "unregister_command_q: unknown error %ld from h_free_crq\n",
+				qrc);
+			rc = ERROR;
+			break;
+		}
+
+		/*
+		 * dont wait more then 300 seconds
+		 * ticks are in milliseconds more or less
+		 */
+		if (ticks > 300000 && qrc != H_SUCCESS) {
+			rc = ERROR;
+			dev_err(&vscsi->dev, "Excessive wait for h_free_crq\n");
+		}
+	} while (qrc != H_SUCCESS && rc == ADAPT_SUCCESS);
+
+	pr_debug("Freeing CRQ: phyp rc %ld, rc %ld\n", qrc, rc);
+
+	return rc;
+}
+
+/**
+ * ibmvscsis_delete_client_info() - Helper function to Delete Client Info
+ * @vscsi:	Pointer to our adapter structure
+ * @client_closed:	True if client closed its queue
+ *
+ * Deletes information specific to the client when the client goes away
+ *
+ * EXECUTION ENVIRONMENT:
+ *	Interrupt or Process
+ */
+static void ibmvscsis_delete_client_info(struct scsi_info *vscsi,
+					 bool client_closed)
+{
+	vscsi->client_cap = 0;
+
+	/*
+	 * Some things we don't want to clear if we're closing the queue,
+	 * because some clients don't resend the host handshake when they
+	 * get a transport event.
+	 */
+	if (client_closed)
+		vscsi->client_data.os_type = 0;
+}
+
+/**
+ * ibmvscsis_free_command_q() - Free Command Queue
+ * @vscsi:	Pointer to our adapter structure
+ *
+ * This function calls unregister_command_q, then clears interrupts and
+ * any pending interrupt acknowledgments associated with the command q.
+ * It also clears memory if there is no error.
+ *
+ * PHYP did not meet the PAPR architecture so that we must give up the
+ * lock. This causes a timing hole regarding state change.  To close the
+ * hole this routine does accounting on any change that occurred during
+ * the time the lock is not held.
+ * NOTE: must give up and then acquire the interrupt lock, the caller must
+ *	 make sure that state and or flags will prevent interrupt handler from
+ *	 scheduling work.
+ *
+ * EXECUTION ENVIRONMENT:
+ *	Process level, interrupt lock is held
+ */
+static long ibmvscsis_free_command_q(struct scsi_info *vscsi)
+{
+	int bytes;
+	u32 flags_under_lock;
+	u16 state_under_lock;
+	long rc = ADAPT_SUCCESS;
+
+	if (!(vscsi->flags & CRQ_CLOSED)) {
+		vio_disable_interrupts(vscsi->dma_dev);
+
+		state_under_lock = vscsi->new_state;
+		flags_under_lock = vscsi->flags;
+		vscsi->phyp_acr_state = 0;
+		vscsi->phyp_acr_flags = 0;
+
+		spin_unlock_bh(&vscsi->intr_lock);
+		rc = ibmvscsis_unregister_command_q(vscsi);
+		spin_lock_bh(&vscsi->intr_lock);
+
+		if (state_under_lock != vscsi->new_state)
+			vscsi->phyp_acr_state = vscsi->new_state;
+
+		vscsi->phyp_acr_flags = ((~flags_under_lock) & vscsi->flags);
+
+		if (rc == ADAPT_SUCCESS) {
+			bytes = vscsi->cmd_q.size * PAGE_SIZE;
+			memset(vscsi->cmd_q.base_addr, 0, bytes);
+			vscsi->cmd_q.index = 0;
+			vscsi->flags |= CRQ_CLOSED;
+
+			ibmvscsis_delete_client_info(vscsi, false);
+		}
+
+		pr_debug("free_command_q: flags 0x%x, state 0x%hx, acr_flags 0x%x, acr_state 0x%hx\n",
+			 vscsi->flags, vscsi->state, vscsi->phyp_acr_flags,
+			 vscsi->phyp_acr_state);
+	}
+	return rc;
+}
+
+/**
+ * ibmvscsis_cmd_q_dequeue() - Get valid Command element
+ * @mask:	Mask to use in case index wraps
+ * @current_index:	Current index into command queue
+ * @base_addr:	Pointer to start of command queue
+ *
+ * Returns a pointer to a valid command element or NULL, if the command
+ * queue is empty
+ *
+ * EXECUTION ENVIRONMENT:
+ *	Interrupt environment, interrupt lock held
+ */
+static struct viosrp_crq *ibmvscsis_cmd_q_dequeue(uint mask,
+						  uint *current_index,
+						  struct viosrp_crq *base_addr)
+{
+	struct viosrp_crq *ptr;
+
+	ptr = base_addr + *current_index;
+
+	if (ptr->valid) {
+		*current_index = (*current_index + 1) & mask;
+		dma_rmb();
+	} else {
+		ptr = NULL;
+	}
+
+	return ptr;
+}
+
+/**
+ * ibmvscsis_send_init_message() -  send initialize message to the client
+ * @vscsi:	Pointer to our adapter structure
+ * @format:	Which Init Message format to send
+ *
+ * EXECUTION ENVIRONMENT:
+ *	Interrupt environment interrupt lock held
+ */
+static long ibmvscsis_send_init_message(struct scsi_info *vscsi, u8 format)
+{
+	struct viosrp_crq *crq;
+	u64 buffer[2] = { 0, 0 };
+	long rc;
+
+	crq = (struct viosrp_crq *)&buffer;
+	crq->valid = VALID_INIT_MSG;
+	crq->format = format;
+	rc = h_send_crq(vscsi->dds.unit_id, cpu_to_be64(buffer[MSG_HI]),
+			cpu_to_be64(buffer[MSG_LOW]));
+
+	return rc;
+}
+
+/**
+ * ibmvscsis_check_init_msg() - Check init message valid
+ * @vscsi:	Pointer to our adapter structure
+ * @format:	Pointer to return format of Init Message, if any.
+ *		Set to UNUSED_FORMAT if no Init Message in queue.
+ *
+ * Checks if an initialize message was queued by the initiatior
+ * after the queue was created and before the interrupt was enabled.
+ *
+ * EXECUTION ENVIRONMENT:
+ *	Process level only, interrupt lock held
+ */
+static long ibmvscsis_check_init_msg(struct scsi_info *vscsi, uint *format)
+{
+	struct viosrp_crq *crq;
+	long rc = ADAPT_SUCCESS;
+
+	crq = ibmvscsis_cmd_q_dequeue(vscsi->cmd_q.mask, &vscsi->cmd_q.index,
+				      vscsi->cmd_q.base_addr);
+	if (!crq) {
+		*format = (uint)UNUSED_FORMAT;
+	} else if (crq->valid == VALID_INIT_MSG && crq->format == INIT_MSG) {
+		*format = (uint)INIT_MSG;
+		crq->valid = INVALIDATE_CMD_RESP_EL;
+		dma_rmb();
+
+		/*
+		 * the caller has ensured no initialize message was
+		 * sent after the queue was
+		 * created so there should be no other message on the queue.
+		 */
+		crq = ibmvscsis_cmd_q_dequeue(vscsi->cmd_q.mask,
+					      &vscsi->cmd_q.index,
+					      vscsi->cmd_q.base_addr);
+		if (crq) {
+			*format = (uint)(crq->format);
+			rc =  ERROR;
+			crq->valid = INVALIDATE_CMD_RESP_EL;
+			dma_rmb();
+		}
+	} else {
+		*format = (uint)(crq->format);
+		rc =  ERROR;
+		crq->valid = INVALIDATE_CMD_RESP_EL;
+		dma_rmb();
+	}
+
+	return rc;
+}
+
+/**
+ * ibmvscsis_establish_new_q() - Establish new CRQ queue
+ * @vscsi:	Pointer to our adapter structure
+ * @new_state:	New state being established after resetting the queue
+ *
+ * Must be called with interrupt lock held.
+ */
+static long ibmvscsis_establish_new_q(struct scsi_info *vscsi,  uint new_state)
+{
+	long rc = ADAPT_SUCCESS;
+	uint format;
+
+	vscsi->flags &= PRESERVE_FLAG_FIELDS;
+	vscsi->rsp_q_timer.timer_pops = 0;
+	vscsi->debit = 0;
+	vscsi->credit = 0;
+
+	rc = vio_enable_interrupts(vscsi->dma_dev);
+	if (rc) {
+		pr_warn("reset_queue: failed to enable interrupts, rc %ld\n",
+			rc);
+		return rc;
+	}
+
+	rc = ibmvscsis_check_init_msg(vscsi, &format);
+	if (rc) {
+		dev_err(&vscsi->dev, "reset_queue: check_init_msg failed, rc %ld\n",
+			rc);
+		return rc;
+	}
+
+	if (format == UNUSED_FORMAT && new_state == WAIT_CONNECTION) {
+		rc = ibmvscsis_send_init_message(vscsi, INIT_MSG);
+		switch (rc) {
+		case H_SUCCESS:
+		case H_DROPPED:
+		case H_CLOSED:
+			rc = ADAPT_SUCCESS;
+			break;
+
+		case H_PARAMETER:
+		case H_HARDWARE:
+			break;
+
+		default:
+			vscsi->state = UNDEFINED;
+			rc = H_HARDWARE;
+			break;
+		}
+	}
+
+	return rc;
+}
+
+/**
+ * ibmvscsis_reset_queue() - Reset CRQ Queue
+ * @vscsi:	Pointer to our adapter structure
+ * @new_state:	New state to establish after resetting the queue
+ *
+ * This function calls h_free_q and then calls h_reg_q and does all
+ * of the bookkeeping to get us back to where we can communicate.
+ *
+ * Actually, we don't always call h_free_crq.  A problem was discovered
+ * where one partition would close and reopen his queue, which would
+ * cause his partner to get a transport event, which would cause him to
+ * close and reopen his queue, which would cause the original partition
+ * to get a transport event, etc., etc.  To prevent this, we don't
+ * actually close our queue if the client initiated the reset, (i.e.
+ * either we got a transport event or we have detected that the client's
+ * queue is gone)
+ *
+ * EXECUTION ENVIRONMENT:
+ *	Process environment, called with interrupt lock held
+ */
+static void ibmvscsis_reset_queue(struct scsi_info *vscsi, uint new_state)
+{
+	int bytes;
+	long rc = ADAPT_SUCCESS;
+
+	pr_debug("reset_queue: flags 0x%x\n", vscsi->flags);
+
+	/* don't reset, the client did it for us */
+	if (vscsi->flags & (CLIENT_FAILED | TRANS_EVENT)) {
+		vscsi->flags &=  PRESERVE_FLAG_FIELDS;
+		vscsi->rsp_q_timer.timer_pops = 0;
+		vscsi->debit = 0;
+		vscsi->credit = 0;
+		vscsi->state = new_state;
+		vio_enable_interrupts(vscsi->dma_dev);
+	} else {
+		rc = ibmvscsis_free_command_q(vscsi);
+		if (rc == ADAPT_SUCCESS) {
+			vscsi->state = new_state;
+
+			bytes = vscsi->cmd_q.size * PAGE_SIZE;
+			rc = h_reg_crq(vscsi->dds.unit_id,
+				       vscsi->cmd_q.crq_token, bytes);
+			if (rc == H_CLOSED || rc == H_SUCCESS) {
+				rc = ibmvscsis_establish_new_q(vscsi,
+							       new_state);
+			}
+
+			if (rc != ADAPT_SUCCESS) {
+				pr_debug("reset_queue: reg_crq rc %ld\n", rc);
+
+				vscsi->state = ERR_DISCONNECTED;
+				vscsi->flags |=  RESPONSE_Q_DOWN;
+				ibmvscsis_free_command_q(vscsi);
+			}
+		} else {
+			vscsi->state = ERR_DISCONNECTED;
+			vscsi->flags |= RESPONSE_Q_DOWN;
+		}
+	}
+}
+
+/**
+ * ibmvscsis_free_cmd_resources() - Free command resources
+ * @vscsi:	Pointer to our adapter structure
+ * @cmd:	Command which is not longer in use
+ *
+ * Must be called with interrupt lock held.
+ */
+static void ibmvscsis_free_cmd_resources(struct scsi_info *vscsi,
+					 struct ibmvscsis_cmd *cmd)
+{
+	struct iu_entry *iue = cmd->iue;
+
+	switch (cmd->type) {
+	case TASK_MANAGEMENT:
+	case SCSI_CDB:
+		/*
+		 * When the queue goes down this value is cleared, so it
+		 * cannot be cleared in this general purpose function.
+		 */
+		if (vscsi->debit)
+			vscsi->debit -= 1;
+		break;
+	case ADAPTER_MAD:
+		vscsi->flags &= ~PROCESSING_MAD;
+		break;
+	case UNSET_TYPE:
+		break;
+	default:
+		dev_err(&vscsi->dev, "free_cmd_resources unknown type %d\n",
+			cmd->type);
+		break;
+	}
+
+	cmd->iue = NULL;
+	list_add_tail(&cmd->list, &vscsi->free_cmd);
+	srp_iu_put(iue);
+
+	if (list_empty(&vscsi->active_q) && list_empty(&vscsi->schedule_q) &&
+	    list_empty(&vscsi->waiting_rsp) && (vscsi->flags & WAIT_FOR_IDLE)) {
+		vscsi->flags &= ~WAIT_FOR_IDLE;
+		complete(&vscsi->wait_idle);
+	}
+}
+
+/**
+ * ibmvscsis_disconnect() - Helper function to disconnect
+ * @work:	Pointer to work_struct, gives access to our adapter structure
+ *
+ * An error has occurred or the driver received a Transport event,
+ * and the driver is requesting that the command queue be de-registered
+ * in a safe manner. If there is no outstanding I/O then we can stop the
+ * queue. If we are restarting the queue it will be reflected in the
+ * the state of the adapter.
+ *
+ * EXECUTION ENVIRONMENT:
+ *	Process environment
+ */
+static void ibmvscsis_disconnect(struct work_struct *work)
+{
+	struct scsi_info *vscsi = container_of(work, struct scsi_info,
+					       proc_work);
+	u16 new_state;
+	bool wait_idle = false;
+	long rc = ADAPT_SUCCESS;
+
+	spin_lock_bh(&vscsi->intr_lock);
+	new_state = vscsi->new_state;
+	vscsi->new_state = 0;
+
+	pr_debug("disconnect: flags 0x%x, state 0x%hx\n", vscsi->flags,
+		 vscsi->state);
+
+	/*
+	 * check which state we are in and see if we
+	 * should transitition to the new state
+	 */
+	switch (vscsi->state) {
+	/*  Should never be called while in this state. */
+	case NO_QUEUE:
+	/*
+	 * Can never transition from this state;
+	 * igonore errors and logout.
+	 */
+	case UNCONFIGURING:
+		break;
+
+	/* can transition from this state to UNCONFIGURING */
+	case ERR_DISCONNECT:
+		if (new_state == UNCONFIGURING)
+			vscsi->state = new_state;
+		break;
+
+	/*
+	 * Can transition from this state to to unconfiguring
+	 * or err disconnect.
+	 */
+	case ERR_DISCONNECT_RECONNECT:
+		switch (new_state) {
+		case UNCONFIGURING:
+		case ERR_DISCONNECT:
+			vscsi->state = new_state;
+			break;
+
+		case WAIT_IDLE:
+			break;
+		default:
+			break;
+		}
+		break;
+
+	/* can transition from this state to UNCONFIGURING */
+	case ERR_DISCONNECTED:
+		if (new_state == UNCONFIGURING)
+			vscsi->state = new_state;
+		break;
+
+	/*
+	 * If this is a transition into an error state.
+	 * a client is attempting to establish a connection
+	 * and has violated the RPA protocol.
+	 * There can be nothing pending on the adapter although
+	 * there can be requests in the command queue.
+	 */
+	case WAIT_ENABLED:
+	case PART_UP_WAIT_ENAB:
+		switch (new_state) {
+		case ERR_DISCONNECT:
+			vscsi->flags |= RESPONSE_Q_DOWN;
+			vscsi->state = new_state;
+			vscsi->flags &= ~(SCHEDULE_DISCONNECT |
+					  DISCONNECT_SCHEDULED);
+			ibmvscsis_free_command_q(vscsi);
+			break;
+		case ERR_DISCONNECT_RECONNECT:
+			ibmvscsis_reset_queue(vscsi, WAIT_ENABLED);
+			break;
+
+		/* should never happen */
+		case WAIT_IDLE:
+			rc = ERROR;
+			dev_err(&vscsi->dev, "disconnect: invalid state %d for WAIT_IDLE\n",
+				vscsi->state);
+			break;
+		}
+		break;
+
+	case WAIT_IDLE:
+		switch (new_state) {
+		case ERR_DISCONNECT:
+		case ERR_DISCONNECT_RECONNECT:
+			vscsi->state = new_state;
+			break;
+		}
+		break;
+
+	/*
+	 * Initiator has not done a successful srp login
+	 * or has done a successful srp logout ( adapter was not
+	 * busy). In the first case there can be responses queued
+	 * waiting for space on the initiators response queue (MAD)
+	 * The second case the adapter is idle. Assume the worse case,
+	 * i.e. the second case.
+	 */
+	case WAIT_CONNECTION:
+	case CONNECTED:
+	case SRP_PROCESSING:
+		wait_idle = true;
+		vscsi->state = new_state;
+		break;
+
+	/* can transition from this state to UNCONFIGURING */
+	case UNDEFINED:
+		if (new_state == UNCONFIGURING)
+			vscsi->state = new_state;
+		break;
+	default:
+		break;
+	}
+
+	if (wait_idle) {
+		pr_debug("disconnect start wait, active %d, sched %d\n",
+			 (int)list_empty(&vscsi->active_q),
+			 (int)list_empty(&vscsi->schedule_q));
+		if (!list_empty(&vscsi->active_q) ||
+		    !list_empty(&vscsi->schedule_q)) {
+			vscsi->flags |= WAIT_FOR_IDLE;
+			pr_debug("disconnect flags 0x%x\n", vscsi->flags);
+			/*
+			 * This routine is can not be called with the interrupt
+			 * lock held.
+			 */
+			spin_unlock_bh(&vscsi->intr_lock);
+			wait_for_completion(&vscsi->wait_idle);
+			spin_lock_bh(&vscsi->intr_lock);
+		}
+		pr_debug("disconnect stop wait\n");
+
+		ibmvscsis_adapter_idle(vscsi);
+	}
+
+	spin_unlock_bh(&vscsi->intr_lock);
+}
+
+/**
+ * ibmvscsis_post_disconnect() - Schedule the disconnect
+ * @vscsi:	Pointer to our adapter structure
+ * @new_state:	State to move to after disconnecting
+ * @flag_bits:	Flags to turn on in adapter structure
+ *
+ * If it's already been scheduled, then see if we need to "upgrade"
+ * the new state (if the one passed in is more "severe" than the
+ * previous one).
+ *
+ * PRECONDITION:
+ *	interrupt lock is held
+ */
+static void ibmvscsis_post_disconnect(struct scsi_info *vscsi, uint new_state,
+				      uint flag_bits)
+{
+	uint state;
+
+	/* check the validity of the new state */
+	switch (new_state) {
+	case UNCONFIGURING:
+	case ERR_DISCONNECT:
+	case ERR_DISCONNECT_RECONNECT:
+	case WAIT_IDLE:
+		break;
+
+	default:
+		dev_err(&vscsi->dev, "post_disconnect: Invalid new state %d\n",
+			new_state);
+		return;
+	}
+
+	vscsi->flags |= flag_bits;
+
+	pr_debug("post_disconnect: new_state 0x%x, flag_bits 0x%x, vscsi->flags 0x%x, state %hx\n",
+		 new_state, flag_bits, vscsi->flags, vscsi->state);
+
+	if (!(vscsi->flags & (DISCONNECT_SCHEDULED | SCHEDULE_DISCONNECT))) {
+		vscsi->flags |= SCHEDULE_DISCONNECT;
+		vscsi->new_state = new_state;
+
+		INIT_WORK(&vscsi->proc_work, ibmvscsis_disconnect);
+		(void)queue_work(vscsi->work_q, &vscsi->proc_work);
+	} else {
+		if (vscsi->new_state)
+			state = vscsi->new_state;
+		else
+			state = vscsi->state;
+
+		switch (state) {
+		case NO_QUEUE:
+		case UNCONFIGURING:
+			break;
+
+		case ERR_DISCONNECTED:
+		case ERR_DISCONNECT:
+		case UNDEFINED:
+			if (new_state == UNCONFIGURING)
+				vscsi->new_state = new_state;
+			break;
+
+		case ERR_DISCONNECT_RECONNECT:
+			switch (new_state) {
+			case UNCONFIGURING:
+			case ERR_DISCONNECT:
+				vscsi->new_state = new_state;
+				break;
+			default:
+				break;
+			}
+			break;
+
+		case WAIT_ENABLED:
+		case PART_UP_WAIT_ENAB:
+		case WAIT_IDLE:
+		case WAIT_CONNECTION:
+		case CONNECTED:
+		case SRP_PROCESSING:
+			vscsi->new_state = new_state;
+			break;
+
+		default:
+			break;
+		}
+	}
+
+	pr_debug("Leaving post_disconnect: flags 0x%x, new_state 0x%x\n",
+		 vscsi->flags, vscsi->new_state);
+}
+
+/**
+ * ibmvscsis_trans_event() - Handle a Transport Event
+ * @vscsi:	Pointer to our adapter structure
+ * @crq:	Pointer to CRQ entry containing the Transport Event
+ *
+ * Do the logic to close the I_T nexus.  This function may not
+ * behave to specification.
+ *
+ * EXECUTION ENVIRONMENT:
+ *	Interrupt, interrupt lock held
+ */
+static long ibmvscsis_trans_event(struct scsi_info *vscsi,
+				  struct viosrp_crq *crq)
+{
+	long rc = ADAPT_SUCCESS;
+
+	pr_debug("trans_event: format %d, flags 0x%x, state 0x%hx\n",
+		 (int)crq->format, vscsi->flags, vscsi->state);
+
+	switch (crq->format) {
+	case MIGRATED:
+	case PARTNER_FAILED:
+	case PARTNER_DEREGISTER:
+		ibmvscsis_delete_client_info(vscsi, true);
+		break;
+
+	default:
+		rc = ERROR;
+		dev_err(&vscsi->dev, "trans_event: invalid format %d\n",
+			(uint)crq->format);
+		ibmvscsis_post_disconnect(vscsi, ERR_DISCONNECT,
+					  RESPONSE_Q_DOWN);
+		break;
+	}
+
+	if (rc == ADAPT_SUCCESS) {
+		switch (vscsi->state) {
+		case NO_QUEUE:
+		case ERR_DISCONNECTED:
+		case UNDEFINED:
+			break;
+
+		case UNCONFIGURING:
+			vscsi->flags |= (RESPONSE_Q_DOWN | TRANS_EVENT);
+			break;
+
+		case WAIT_ENABLED:
+			break;
+
+		case WAIT_CONNECTION:
+			break;
+
+		case CONNECTED:
+			ibmvscsis_post_disconnect(vscsi, WAIT_IDLE,
+						  (RESPONSE_Q_DOWN |
+						   TRANS_EVENT));
+			break;
+
+		case PART_UP_WAIT_ENAB:
+			vscsi->state = WAIT_ENABLED;
+			break;
+
+		case SRP_PROCESSING:
+			if ((vscsi->debit > 0) ||
+			    !list_empty(&vscsi->schedule_q) ||
+			    !list_empty(&vscsi->waiting_rsp) ||
+			    !list_empty(&vscsi->active_q)) {
+				pr_debug("debit %d, sched %d, wait %d, active %d\n",
+					 vscsi->debit,
+					 (int)list_empty(&vscsi->schedule_q),
+					 (int)list_empty(&vscsi->waiting_rsp),
+					 (int)list_empty(&vscsi->active_q));
+				pr_warn("connection lost with outstanding work\n");
+			} else {
+				pr_debug("trans_event: SRP Processing, but no outstanding work\n");
+			}
+
+			ibmvscsis_post_disconnect(vscsi, WAIT_IDLE,
+						  (RESPONSE_Q_DOWN |
+						   TRANS_EVENT));
+			break;
+
+		case ERR_DISCONNECT:
+		case ERR_DISCONNECT_RECONNECT:
+		case WAIT_IDLE:
+			vscsi->flags |= (RESPONSE_Q_DOWN | TRANS_EVENT);
+			break;
+		}
+	}
+
+	rc =  vscsi->flags & SCHEDULE_DISCONNECT;
+
+	pr_debug("Leaving trans_event: flags 0x%x, state 0x%hx, rc %ld\n",
+		 vscsi->flags, vscsi->state, rc);
+
+	return rc;
+}
+
+/**
+ * ibmvscsis_poll_cmd_q() - Poll Command Queue
+ * @vscsi:	Pointer to our adapter structure
+ *
+ * Called to handle command elements that may have arrived while
+ * interrupts were disabled.
+ *
+ * EXECUTION ENVIRONMENT:
+ *	intr_lock must be held
+ */
+static void ibmvscsis_poll_cmd_q(struct scsi_info *vscsi)
+{
+	struct viosrp_crq *crq;
+	long rc;
+	bool ack = true;
+	volatile u8 valid;
+
+	pr_debug("poll_cmd_q: flags 0x%x, state 0x%hx, q index %ud\n",
+		 vscsi->flags, vscsi->state, vscsi->cmd_q.index);
+
+	rc = vscsi->flags & SCHEDULE_DISCONNECT;
+	crq = vscsi->cmd_q.base_addr + vscsi->cmd_q.index;
+	valid = crq->valid;
+	dma_rmb();
+
+	while (valid) {
+poll_work:
+		vscsi->cmd_q.index =
+			(vscsi->cmd_q.index + 1) & vscsi->cmd_q.mask;
+
+		if (!rc) {
+			rc = ibmvscsis_parse_command(vscsi, crq);
+		} else {
+			if ((uint)crq->valid == VALID_TRANS_EVENT) {
+				/*
+				 * must service the transport layer events even
+				 * in an error state, dont break out until all
+				 * the consecutive transport events have been
+				 * processed
+				 */
+				rc = ibmvscsis_trans_event(vscsi, crq);
+			} else if (vscsi->flags & TRANS_EVENT) {
+				/*
+				 * if a tranport event has occurred leave
+				 * everything but transport events on the queue
+				 */
+				pr_debug("poll_cmd_q, ignoring\n");
+
+				/*
+				 * need to decrement the queue index so we can
+				 * look at the elment again
+				 */
+				if (vscsi->cmd_q.index)
+					vscsi->cmd_q.index -= 1;
+				else
+					/*
+					 * index is at 0 it just wrapped.
+					 * have it index last element in q
+					 */
+					vscsi->cmd_q.index = vscsi->cmd_q.mask;
+				break;
+			}
+		}
+
+		crq->valid = INVALIDATE_CMD_RESP_EL;
+
+		crq = vscsi->cmd_q.base_addr + vscsi->cmd_q.index;
+		valid = crq->valid;
+		dma_rmb();
+	}
+
+	if (!rc) {
+		if (ack) {
+			vio_enable_interrupts(vscsi->dma_dev);
+			ack = false;
+			pr_debug("poll_cmd_q, reenabling interrupts\n");
+		}
+		valid = crq->valid;
+		dma_rmb();
+		if (valid)
+			goto poll_work;
+	}
+
+	pr_debug("Leaving poll_cmd_q: rc %ld\n", rc);
+}
+
+/**
+ * ibmvscsis_free_cmd_qs() - Free elements in queue
+ * @vscsi:	Pointer to our adapter structure
+ *
+ * Free all of the elements on all queues that are waiting for
+ * whatever reason.
+ *
+ * PRECONDITION:
+ *	Called with interrupt lock held
+ */
+static void ibmvscsis_free_cmd_qs(struct scsi_info *vscsi)
+{
+	struct ibmvscsis_cmd *cmd, *nxt;
+
+	pr_debug("free_cmd_qs: waiting_rsp empty %d, timer starter %d\n",
+		 (int)list_empty(&vscsi->waiting_rsp),
+		 vscsi->rsp_q_timer.started);
+
+	list_for_each_entry_safe(cmd, nxt, &vscsi->waiting_rsp, list) {
+		list_del(&cmd->list);
+		ibmvscsis_free_cmd_resources(vscsi, cmd);
+	}
+}
+
+/**
+ * ibmvscsis_get_free_cmd() - Get free command from list
+ * @vscsi:	Pointer to our adapter structure
+ *
+ * Must be called with interrupt lock held.
+ */
+static struct ibmvscsis_cmd *ibmvscsis_get_free_cmd(struct scsi_info *vscsi)
+{
+	struct ibmvscsis_cmd *cmd = NULL;
+	struct iu_entry *iue;
+
+	iue = srp_iu_get(&vscsi->target);
+	if (iue) {
+		cmd = list_first_entry_or_null(&vscsi->free_cmd,
+					       struct ibmvscsis_cmd, list);
+		if (cmd) {
+			list_del(&cmd->list);
+			cmd->iue = iue;
+			cmd->type = UNSET_TYPE;
+			memset(&cmd->se_cmd, 0, sizeof(cmd->se_cmd));
+		} else {
+			srp_iu_put(iue);
+		}
+	}
+
+	return cmd;
+}
+
+/**
+ * ibmvscsis_adapter_idle() - Helper function to handle idle adapter
+ * @vscsi:	Pointer to our adapter structure
+ *
+ * This function is called when the adapter is idle when the driver
+ * is attempting to clear an error condition.
+ * The adapter is considered busy if any of its cmd queues
+ * are non-empty. This function can be invoked
+ * from the off level disconnect function.
+ *
+ * EXECUTION ENVIRONMENT:
+ *	Process environment called with interrupt lock held
+ */
+static void ibmvscsis_adapter_idle(struct scsi_info *vscsi)
+{
+	int free_qs = false;
+
+	pr_debug("adapter_idle: flags 0x%x, state 0x%hx\n", vscsi->flags,
+		 vscsi->state);
+
+	/* Only need to free qs if we're disconnecting from client */
+	if (vscsi->state != WAIT_CONNECTION || vscsi->flags & TRANS_EVENT)
+		free_qs = true;
+
+	switch (vscsi->state) {
+	case ERR_DISCONNECT_RECONNECT:
+		ibmvscsis_reset_queue(vscsi, WAIT_CONNECTION);
+		pr_debug("adapter_idle, disc_rec: flags 0x%x\n", vscsi->flags);
+		break;
+
+	case ERR_DISCONNECT:
+		ibmvscsis_free_command_q(vscsi);
+		vscsi->flags &= ~DISCONNECT_SCHEDULED;
+		vscsi->flags |= RESPONSE_Q_DOWN;
+		vscsi->state = ERR_DISCONNECTED;
+		pr_debug("adapter_idle, disc: flags 0x%x, state 0x%hx\n",
+			 vscsi->flags, vscsi->state);
+		break;
+
+	case WAIT_IDLE:
+		vscsi->rsp_q_timer.timer_pops = 0;
+		vscsi->debit = 0;
+		vscsi->credit = 0;
+		if (vscsi->flags & TRANS_EVENT) {
+			vscsi->state = WAIT_CONNECTION;
+			vscsi->flags &= PRESERVE_FLAG_FIELDS;
+		} else {
+			vscsi->state = CONNECTED;
+			vscsi->flags &= ~DISCONNECT_SCHEDULED;