// SPDX-License-Identifier: GPL-2.0-or-later
/* ------------------------------------------------------------
 * ibmvscsi.c
 * (C) Copyright IBM Corporation 1994, 2004
 * Authors: Colin DeVilbiss (devilbis@us.ibm.com)
 *          Santiago Leon (santil@us.ibm.com)
 *          Dave Boutcher (sleddog@us.ibm.com)
 *
 * ------------------------------------------------------------
 * Emulation of a SCSI host adapter for Virtual I/O devices
 *
 * This driver supports the SCSI adapter implemented by the IBM
 * Power5 firmware.  That SCSI adapter is not a physical adapter,
 * but allows Linux SCSI peripheral drivers to directly
 * access devices in another logical partition on the physical system.
 *
 * The virtual adapter(s) are present in the open firmware device
 * tree just like real adapters.
 *
 * One of the capabilities provided on these systems is the ability
 * to DMA between partitions.  The architecture states that for VSCSI,
 * the server side is allowed to DMA to and from the client.  The client
 * is never trusted to DMA to or from the server directly.
 *
 * Messages are sent between partitions on a "Command/Response Queue" 
 * (CRQ), which is just a buffer of 16 byte entries in the receiver's 
 * Senders cannot access the buffer directly, but send messages by
 * making a hypervisor call and passing in the 16 bytes.  The hypervisor
 * puts the message in the next 16 byte space in round-robin fashion,
 * turns on the high order bit of the message (the valid bit), and 
 * generates an interrupt to the receiver (if interrupts are turned on.) 
 * The receiver just turns off the valid bit when they have copied out
 * the message.
 *
 * The VSCSI client builds a SCSI Remote Protocol (SRP) Information Unit
 * (IU) (as defined in the T10 standard available at www.t10.org), gets 
 * a DMA address for the message, and sends it to the server as the
 * payload of a CRQ message.  The server DMAs the SRP IU and processes it,
 * including doing any additional data transfers.  When it is done, it
 * DMAs the SRP response back to the same address as the request came from,
 * and sends a CRQ message back to inform the client that the request has
 * completed.
 *
 * TODO: This is currently pretty tied to the IBM pSeries hypervisor
 * interfaces.  It would be really nice to abstract this above an RDMA
 * layer.
 */

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/dma-mapping.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/pm.h>
#include <linux/kthread.h>
#include <asm/firmware.h>
#include <asm/vio.h>
#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_transport_srp.h>
#include "ibmvscsi.h"

/* The values below are somewhat arbitrary default values, but 
 * OS/400 will use 3 busses (disks, CDs, tapes, I think.)
 * Note that there are 3 bits of channel value, 6 bits of id, and
 * 5 bits of LUN.
 */
static int max_id = 64;
static int max_channel = 3;
static int init_timeout = 300;
static int login_timeout = 60;
static int info_timeout = 30;
static int abort_timeout = 60;
static int reset_timeout = 60;
static int max_requests = IBMVSCSI_MAX_REQUESTS_DEFAULT;
static int max_events = IBMVSCSI_MAX_REQUESTS_DEFAULT + 2;
static int fast_fail = 1;
static int client_reserve = 1;
static char partition_name[96] = "UNKNOWN";
static unsigned int partition_number = -1;
static LIST_HEAD(ibmvscsi_head);
static DEFINE_SPINLOCK(ibmvscsi_driver_lock);

static struct scsi_transport_template *ibmvscsi_transport_template;

#define IBMVSCSI_VERSION "1.5.9"

MODULE_DESCRIPTION("IBM Virtual SCSI");
MODULE_AUTHOR("Dave Boutcher");
MODULE_LICENSE("GPL");
MODULE_VERSION(IBMVSCSI_VERSION);

module_param_named(max_id, max_id, int, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(max_id, "Largest ID value for each channel [Default=64]");
module_param_named(max_channel, max_channel, int, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(max_channel, "Largest channel value [Default=3]");
module_param_named(init_timeout, init_timeout, int, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(init_timeout, "Initialization timeout in seconds");
module_param_named(max_requests, max_requests, int, S_IRUGO);
MODULE_PARM_DESC(max_requests, "Maximum requests for this adapter");
module_param_named(fast_fail, fast_fail, int, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(fast_fail, "Enable fast fail. [Default=1]");
module_param_named(client_reserve, client_reserve, int, S_IRUGO );
MODULE_PARM_DESC(client_reserve, "Attempt client managed reserve/release");

static void ibmvscsi_handle_crq(struct viosrp_crq *crq,
                                struct ibmvscsi_host_data *hostdata);

/* ------------------------------------------------------------
 * Routines for managing the command/response queue
 */
/**
 * ibmvscsi_handle_event: - Interrupt handler for crq events
 * @irq:        number of irq to handle, not used
 * @dev_instance: ibmvscsi_host_data of host that received interrupt
 *
 * Disables interrupts and schedules srp_task
 * Always returns IRQ_HANDLED
 */
static irqreturn_t ibmvscsi_handle_event(int irq, void *dev_instance)
{
        struct ibmvscsi_host_data *hostdata =
            (struct ibmvscsi_host_data *)dev_instance;
        vio_disable_interrupts(to_vio_dev(hostdata->dev));
        tasklet_schedule(&hostdata->srp_task);
        return IRQ_HANDLED;
}

/**
 * ibmvscsi_release_crq_queue() - Deallocates data and unregisters CRQ
 * @queue:              crq_queue to initialize and register
 * @hostdata:           ibmvscsi_host_data of host
 * @max_requests:       maximum requests (unused)
 *
 * Frees irq, deallocates a page for messages, unmaps dma, and unregisters
 * the crq with the hypervisor.
 */
static void ibmvscsi_release_crq_queue(struct crq_queue *queue,
                                       struct ibmvscsi_host_data *hostdata,
                                       int max_requests)
{
        long rc = 0;
        struct vio_dev *vdev = to_vio_dev(hostdata->dev);
        free_irq(vdev->irq, (void *)hostdata);
        tasklet_kill(&hostdata->srp_task);
        do {
                if (rc)
                        msleep(100);
                rc = plpar_hcall_norets(H_FREE_CRQ, vdev->unit_address);
        } while ((rc == H_BUSY) || (H_IS_LONG_BUSY(rc)));
        dma_unmap_single(hostdata->dev,
                         queue->msg_token,
                         queue->size * sizeof(*queue->msgs), DMA_BIDIRECTIONAL);
        free_page((unsigned long)queue->msgs);
}

/**
 * crq_queue_next_crq: - Returns the next entry in message queue
 * @queue:      crq_queue to use
 *
 * Returns pointer to next entry in queue, or NULL if there are no new
 * entried in the CRQ.
 */
static struct viosrp_crq *crq_queue_next_crq(struct crq_queue *queue)
{
        struct viosrp_crq *crq;
        unsigned long flags;

        spin_lock_irqsave(&queue->lock, flags);
        crq = &queue->msgs[queue->cur];
        if (crq->valid != VIOSRP_CRQ_FREE) {
                if (++queue->cur == queue->size)
                        queue->cur = 0;

                /* Ensure the read of the valid bit occurs before reading any
                 * other bits of the CRQ entry
                 */
                rmb();
        } else
                crq = NULL;
        spin_unlock_irqrestore(&queue->lock, flags);

        return crq;
}

/**
 * ibmvscsi_send_crq: - Send a CRQ
 * @hostdata:   the adapter
 * @word1:      the first 64 bits of the data
 * @word2:      the second 64 bits of the data
 */
static int ibmvscsi_send_crq(struct ibmvscsi_host_data *hostdata,
                             u64 word1, u64 word2)
{
        struct vio_dev *vdev = to_vio_dev(hostdata->dev);

        /*
         * Ensure the command buffer is flushed to memory before handing it
         * over to the VIOS to prevent it from fetching any stale data.
         */
        mb();
        return plpar_hcall_norets(H_SEND_CRQ, vdev->unit_address, word1, word2);
}

/**
 * ibmvscsi_task: - Process srps asynchronously
 * @data:       ibmvscsi_host_data of host
 */
static void ibmvscsi_task(void *data)
{
        struct ibmvscsi_host_data *hostdata = (struct ibmvscsi_host_data *)data;
        struct vio_dev *vdev = to_vio_dev(hostdata->dev);
        struct viosrp_crq *crq;
        int done = 0;

        while (!done) {
                /* Pull all the valid messages off the CRQ */
                while ((crq = crq_queue_next_crq(&hostdata->queue)) != NULL) {
                        ibmvscsi_handle_crq(crq, hostdata);
                        crq->valid = VIOSRP_CRQ_FREE;
                        wmb();
                }

                vio_enable_interrupts(vdev);
                crq = crq_queue_next_crq(&hostdata->queue);
                if (crq != NULL) {
                        vio_disable_interrupts(vdev);
                        ibmvscsi_handle_crq(crq, hostdata);
                        crq->valid = VIOSRP_CRQ_FREE;
                        wmb();
                } else {
                        done = 1;
                }
        }
}

static void gather_partition_info(void)
{
        const char *ppartition_name;
        const __be32 *p_number_ptr;

        /* Retrieve information about this partition */
        if (!of_root)
                return;

        of_node_get(of_root);

        ppartition_name = of_get_property(of_root, "ibm,partition-name", NULL);
        if (ppartition_name)
                strscpy(partition_name, ppartition_name,
                                sizeof(partition_name));
        p_number_ptr = of_get_property(of_root, "ibm,partition-no", NULL);
        if (p_number_ptr)
                partition_number = of_read_number(p_number_ptr, 1);
        of_node_put(of_root);
}

static void set_adapter_info(struct ibmvscsi_host_data *hostdata)
{
        memset(&hostdata->madapter_info, 0x00,
                        sizeof(hostdata->madapter_info));

        dev_info(hostdata->dev, "SRP_VERSION: %s\n", SRP_VERSION);
        strcpy(hostdata->madapter_info.srp_version, SRP_VERSION);

        strscpy(hostdata->madapter_info.partition_name, partition_name,
                        sizeof(hostdata->madapter_info.partition_name));

        hostdata->madapter_info.partition_number =
                                        cpu_to_be32(partition_number);

        hostdata->madapter_info.mad_version = cpu_to_be32(SRP_MAD_VERSION_1);
        hostdata->madapter_info.os_type = cpu_to_be32(SRP_MAD_OS_LINUX);
}

/**
 * ibmvscsi_reset_crq_queue() - resets a crq after a failure
 * @queue:      crq_queue to initialize and register
 * @hostdata:   ibmvscsi_host_data of host
 */
static int ibmvscsi_reset_crq_queue(struct crq_queue *queue,
                                    struct ibmvscsi_host_data *hostdata)
{
        int rc = 0;
        struct vio_dev *vdev = to_vio_dev(hostdata->dev);

        /* Close the CRQ */
        do {
                if (rc)
                        msleep(100);
                rc = plpar_hcall_norets(H_FREE_CRQ, vdev->unit_address);
        } while ((rc == H_BUSY) || (H_IS_LONG_BUSY(rc)));

        /* Clean out the queue */
        memset(queue->msgs, 0x00, PAGE_SIZE);
        queue->cur = 0;

        set_adapter_info(hostdata);

        /* And re-open it again */
        rc = plpar_hcall_norets(H_REG_CRQ,
                                vdev->unit_address,
                                queue->msg_token, PAGE_SIZE);
        if (rc == H_CLOSED) {
                /* Adapter is good, but other end is not ready */
                dev_warn(hostdata->dev, "Partner adapter not ready\n");
        } else if (rc != 0) {
                dev_warn(hostdata->dev, "couldn't register crq--rc 0x%x\n", rc);
        }
        return rc;
}

/**
 * ibmvscsi_init_crq_queue() - Initializes and registers CRQ with hypervisor
 * @queue:              crq_queue to initialize and register
 * @hostdata:           ibmvscsi_host_data of host
 * @max_requests:       maximum requests (unused)
 *
 * Allocates a page for messages, maps it for dma, and registers
 * the crq with the hypervisor.
 * Returns zero on success.
 */
static int ibmvscsi_init_crq_queue(struct crq_queue *queue,
                                   struct ibmvscsi_host_data *hostdata,
                                   int max_requests)
{
        int rc;
        int retrc;
        struct vio_dev *vdev = to_vio_dev(hostdata->dev);

        queue->msgs = (struct viosrp_crq *)get_zeroed_page(GFP_KERNEL);

        if (!queue->msgs)
                goto malloc_failed;
        queue->size = PAGE_SIZE / sizeof(*queue->msgs);

        queue->msg_token = dma_map_single(hostdata->dev, queue->msgs,
                                          queue->size * sizeof(*queue->msgs),
                                          DMA_BIDIRECTIONAL);

        if (dma_mapping_error(hostdata->dev, queue->msg_token))
                goto map_failed;

        gather_partition_info();
        set_adapter_info(hostdata);

        retrc = rc = plpar_hcall_norets(H_REG_CRQ,
                                vdev->unit_address,
                                queue->msg_token, PAGE_SIZE);
        if (rc == H_RESOURCE)
                /* maybe kexecing and resource is busy. try a reset */
                rc = ibmvscsi_reset_crq_queue(queue,
                                              hostdata);

        if (rc == H_CLOSED) {
                /* Adapter is good, but other end is not ready */
                dev_warn(hostdata->dev, "Partner adapter not ready\n");
                retrc = 0;
        } else if (rc != 0) {
                dev_warn(hostdata->dev, "Error %d opening adapter\n", rc);
                goto reg_crq_failed;
        }

        queue->cur = 0;
        spin_lock_init(&queue->lock);

        tasklet_init(&hostdata->srp_task, (void *)ibmvscsi_task,
                     (unsigned long)hostdata);

        if (request_irq(vdev->irq,
                        ibmvscsi_handle_event,
                        0, "ibmvscsi", (void *)hostdata) != 0) {
                dev_err(hostdata->dev, "couldn't register irq 0x%x\n",
                        vdev->irq);
                goto req_irq_failed;
        }

        rc = vio_enable_interrupts(vdev);
        if (rc != 0) {
                dev_err(hostdata->dev, "Error %d enabling interrupts!!!\n", rc);
                goto req_irq_failed;
        }

        return retrc;

      req_irq_failed:
        tasklet_kill(&hostdata->srp_task);
        rc = 0;
        do {
                if (rc)
                        msleep(100);
                rc = plpar_hcall_norets(H_FREE_CRQ, vdev->unit_address);
        } while ((rc == H_BUSY) || (H_IS_LONG_BUSY(rc)));
      reg_crq_failed:
        dma_unmap_single(hostdata->dev,
                         queue->msg_token,
                         queue->size * sizeof(*queue->msgs), DMA_BIDIRECTIONAL);
      map_failed:
        free_page((unsigned long)queue->msgs);
      malloc_failed:
        return -1;
}

/**
 * ibmvscsi_reenable_crq_queue() - reenables a crq after
 * @queue:      crq_queue to initialize and register
 * @hostdata:   ibmvscsi_host_data of host
 */
static int ibmvscsi_reenable_crq_queue(struct crq_queue *queue,
                                       struct ibmvscsi_host_data *hostdata)
{
        int rc = 0;
        struct vio_dev *vdev = to_vio_dev(hostdata->dev);

        set_adapter_info(hostdata);

        /* Re-enable the CRQ */
        do {
                if (rc)
                        msleep(100);
                rc = plpar_hcall_norets(H_ENABLE_CRQ, vdev->unit_address);
        } while ((rc == H_IN_PROGRESS) || (rc == H_BUSY) || (H_IS_LONG_BUSY(rc)));

        if (rc)
                dev_err(hostdata->dev, "Error %d enabling adapter\n", rc);
        return rc;
}

/* ------------------------------------------------------------
 * Routines for the event pool and event structs
 */
/**
 * initialize_event_pool: - Allocates and initializes the event pool for a host
 * @pool:       event_pool to be initialized
 * @size:       Number of events in pool
 * @hostdata:   ibmvscsi_host_data who owns the event pool
 *
 * Returns zero on success.
 */
static int initialize_event_pool(struct event_pool *pool,
                                 int size, struct ibmvscsi_host_data *hostdata)
{
        int i;

        pool->size = size;
        pool->next = 0;
        pool->events = kzalloc_objs(*pool->events, pool->size);
        if (!pool->events)
                return -ENOMEM;

        pool->iu_storage =
            dma_alloc_coherent(hostdata->dev,
                               pool->size * sizeof(*pool->iu_storage),
                               &pool->iu_token, GFP_KERNEL);
        if (!pool->iu_storage) {
                kfree(pool->events);
                return -ENOMEM;
        }

        for (i = 0; i < pool->size; ++i) {
                struct srp_event_struct *evt = &pool->events[i];
                memset(&evt->crq, 0x00, sizeof(evt->crq));
                atomic_set(&evt->free, 1);
                evt->crq.valid = VIOSRP_CRQ_CMD_RSP;
                evt->crq.IU_length = cpu_to_be16(sizeof(*evt->xfer_iu));
                evt->crq.IU_data_ptr = cpu_to_be64(pool->iu_token +
                        sizeof(*evt->xfer_iu) * i);
                evt->xfer_iu = pool->iu_storage + i;
                evt->hostdata = hostdata;
                evt->ext_list = NULL;
                evt->ext_list_token = 0;
        }

        return 0;
}

/**
 * release_event_pool() - Frees memory of an event pool of a host
 * @pool:       event_pool to be released
 * @hostdata:   ibmvscsi_host_data who owns the even pool
 *
 * Returns zero on success.
 */
static void release_event_pool(struct event_pool *pool,
                               struct ibmvscsi_host_data *hostdata)
{
        int i, in_use = 0;
        for (i = 0; i < pool->size; ++i) {
                if (atomic_read(&pool->events[i].free) != 1)
                        ++in_use;
                if (pool->events[i].ext_list) {
                        dma_free_coherent(hostdata->dev,
                                  SG_ALL * sizeof(struct srp_direct_buf),
                                  pool->events[i].ext_list,
                                  pool->events[i].ext_list_token);
                }
        }
        if (in_use)
                dev_warn(hostdata->dev, "releasing event pool with %d "
                         "events still in use?\n", in_use);
        kfree(pool->events);
        dma_free_coherent(hostdata->dev,
                          pool->size * sizeof(*pool->iu_storage),
                          pool->iu_storage, pool->iu_token);
}

/**
 * valid_event_struct: - Determines if event is valid.
 * @pool:       event_pool that contains the event
 * @evt:        srp_event_struct to be checked for validity
 *
 * Returns zero if event is invalid, one otherwise.
*/
static int valid_event_struct(struct event_pool *pool,
                                struct srp_event_struct *evt)
{
        int index = evt - pool->events;
        if (index < 0 || index >= pool->size)   /* outside of bounds */
                return 0;
        if (evt != pool->events + index)        /* unaligned */
                return 0;
        return 1;
}

/**
 * free_event_struct() - Changes status of event to "free"
 * @pool:       event_pool that contains the event
 * @evt:        srp_event_struct to be modified
 */
static void free_event_struct(struct event_pool *pool,
                                       struct srp_event_struct *evt)
{
        if (!valid_event_struct(pool, evt)) {
                dev_err(evt->hostdata->dev, "Freeing invalid event_struct %p "
                        "(not in pool %p)\n", evt, pool->events);
                return;
        }
        if (atomic_inc_return(&evt->free) != 1) {
                dev_err(evt->hostdata->dev, "Freeing event_struct %p "
                        "which is not in use!\n", evt);
                return;
        }
}

/**
 * get_event_struct() - Gets the next free event in pool
 * @pool:       event_pool that contains the events to be searched
 *
 * Returns the next event in "free" state, and NULL if none are free.
 * Note that no synchronization is done here, we assume the host_lock
 * will syncrhonze things.
*/
static struct srp_event_struct *get_event_struct(struct event_pool *pool)
{
        int i;
        int poolsize = pool->size;
        int offset = pool->next;

        for (i = 0; i < poolsize; i++) {
                offset = (offset + 1) % poolsize;
                if (!atomic_dec_if_positive(&pool->events[offset].free)) {
                        pool->next = offset;
                        return &pool->events[offset];
                }
        }

        printk(KERN_ERR "ibmvscsi: found no event struct in pool!\n");
        return NULL;
}

/**
 * init_event_struct: Initialize fields in an event struct that are always 
 *                    required.
 * @evt_struct: The event
 * @done:       Routine to call when the event is responded to
 * @format:     SRP or MAD format
 * @timeout:    timeout value set in the CRQ
 */
static void init_event_struct(struct srp_event_struct *evt_struct,
                              void (*done) (struct srp_event_struct *),
                              u8 format,
                              int timeout)
{
        evt_struct->cmnd = NULL;
        evt_struct->cmnd_done = NULL;
        evt_struct->sync_srp = NULL;
        evt_struct->crq.format = format;
        evt_struct->crq.timeout = cpu_to_be16(timeout);
        evt_struct->done = done;
}

/* ------------------------------------------------------------
 * Routines for receiving SCSI responses from the hosting partition
 */

/*
 * set_srp_direction: Set the fields in the srp related to data
 *     direction and number of buffers based on the direction in
 *     the scsi_cmnd and the number of buffers
 */
static void set_srp_direction(struct scsi_cmnd *cmd,
                              struct srp_cmd *srp_cmd, 
                              int numbuf)
{
        u8 fmt;

        if (numbuf == 0)
                return;
        
        if (numbuf == 1)
                fmt = SRP_DATA_DESC_DIRECT;
        else {
                fmt = SRP_DATA_DESC_INDIRECT;
                numbuf = min(numbuf, MAX_INDIRECT_BUFS);

                if (cmd->sc_data_direction == DMA_TO_DEVICE)
                        srp_cmd->data_out_desc_cnt = numbuf;
                else
                        srp_cmd->data_in_desc_cnt = numbuf;
        }

        if (cmd->sc_data_direction == DMA_TO_DEVICE)
                srp_cmd->buf_fmt = fmt << 4;
        else
                srp_cmd->buf_fmt = fmt;
}

/**
 * unmap_cmd_data: - Unmap data pointed in srp_cmd based on the format
 * @cmd:        srp_cmd whose additional_data member will be unmapped
 * @evt_struct: the event
 * @dev:        device for which the memory is mapped
 */
static void unmap_cmd_data(struct srp_cmd *cmd,
                           struct srp_event_struct *evt_struct,
                           struct device *dev)
{
        u8 out_fmt, in_fmt;

        out_fmt = cmd->buf_fmt >> 4;
        in_fmt = cmd->buf_fmt & ((1U << 4) - 1);

        if (out_fmt == SRP_NO_DATA_DESC && in_fmt == SRP_NO_DATA_DESC)
                return;

        if (evt_struct->cmnd)
                scsi_dma_unmap(evt_struct->cmnd);
}

static int map_sg_list(struct scsi_cmnd *cmd, int nseg,
                       struct srp_direct_buf *md)
{
        int i;
        struct scatterlist *sg;
        u64 total_length = 0;

        scsi_for_each_sg(cmd, sg, nseg, i) {
                struct srp_direct_buf *descr = md + i;
                descr->va = cpu_to_be64(sg_dma_address(sg));
                descr->len = cpu_to_be32(sg_dma_len(sg));
                descr->key = 0;
                total_length += sg_dma_len(sg);
        }
        return total_length;
}

/**
 * map_sg_data: - Maps dma for a scatterlist and initializes descriptor fields
 * @cmd:        struct scsi_cmnd with the scatterlist
 * @evt_struct: struct srp_event_struct to map
 * @srp_cmd:    srp_cmd that contains the memory descriptor
 * @dev:        device for which to map dma memory
 *
 * Called by map_data_for_srp_cmd() when building srp cmd from scsi cmd.
 * Returns 1 on success.
*/
static int map_sg_data(struct scsi_cmnd *cmd,
                       struct srp_event_struct *evt_struct,
                       struct srp_cmd *srp_cmd, struct device *dev)
{

        int sg_mapped;
        u64 total_length = 0;
        struct srp_direct_buf *data =
                (struct srp_direct_buf *) srp_cmd->add_data;
        struct srp_indirect_buf *indirect =
                (struct srp_indirect_buf *) data;

        sg_mapped = scsi_dma_map(cmd);
        if (!sg_mapped)
                return 1;
        else if (sg_mapped < 0)
                return 0;

        set_srp_direction(cmd, srp_cmd, sg_mapped);

        /* special case; we can use a single direct descriptor */
        if (sg_mapped == 1) {
                map_sg_list(cmd, sg_mapped, data);
                return 1;
        }

        indirect->table_desc.va = 0;
        indirect->table_desc.len = cpu_to_be32(sg_mapped *
                                               sizeof(struct srp_direct_buf));
        indirect->table_desc.key = 0;

        if (sg_mapped <= MAX_INDIRECT_BUFS) {
                total_length = map_sg_list(cmd, sg_mapped,
                                           &indirect->desc_list[0]);
                indirect->len = cpu_to_be32(total_length);
                return 1;
        }

        /* get indirect table */
        if (!evt_struct->ext_list) {
                evt_struct->ext_list = dma_alloc_coherent(dev,
                                           SG_ALL * sizeof(struct srp_direct_buf),
                                           &evt_struct->ext_list_token, 0);
                if (!evt_struct->ext_list) {
                        if (!firmware_has_feature(FW_FEATURE_CMO))
                                sdev_printk(KERN_ERR, cmd->device,
                                            "Can't allocate memory "
                                            "for indirect table\n");
                        scsi_dma_unmap(cmd);
                        return 0;
                }
        }

        total_length = map_sg_list(cmd, sg_mapped, evt_struct->ext_list);

        indirect->len = cpu_to_be32(total_length);
        indirect->table_desc.va = cpu_to_be64(evt_struct->ext_list_token);
        indirect->table_desc.len = cpu_to_be32(sg_mapped *
                                               sizeof(indirect->desc_list[0]));
        memcpy(indirect->desc_list, evt_struct->ext_list,
               MAX_INDIRECT_BUFS * sizeof(struct srp_direct_buf));
        return 1;
}

/**
 * map_data_for_srp_cmd: - Calls functions to map data for srp cmds
 * @cmd:        struct scsi_cmnd with the memory to be mapped
 * @evt_struct: struct srp_event_struct to map
 * @srp_cmd:    srp_cmd that contains the memory descriptor
 * @dev:        dma device for which to map dma memory
 *
 * Called by scsi_cmd_to_srp_cmd() when converting scsi cmds to srp cmds 
 * Returns 1 on success.
*/
static int map_data_for_srp_cmd(struct scsi_cmnd *cmd,
                                struct srp_event_struct *evt_struct,
                                struct srp_cmd *srp_cmd, struct device *dev)
{
        switch (cmd->sc_data_direction) {
        case DMA_FROM_DEVICE:
        case DMA_TO_DEVICE:
                break;
        case DMA_NONE:
                return 1;
        case DMA_BIDIRECTIONAL:
                sdev_printk(KERN_ERR, cmd->device,
                            "Can't map DMA_BIDIRECTIONAL to read/write\n");
                return 0;
        default:
                sdev_printk(KERN_ERR, cmd->device,
                            "Unknown data direction 0x%02x; can't map!\n",
                            cmd->sc_data_direction);
                return 0;
        }

        return map_sg_data(cmd, evt_struct, srp_cmd, dev);
}

/**
 * purge_requests: Our virtual adapter just shut down.  purge any sent requests
 * @hostdata:    the adapter
 * @error_code:  error code to return as the 'result'
 */
static void purge_requests(struct ibmvscsi_host_data *hostdata, int error_code)
{
        struct srp_event_struct *evt;
        unsigned long flags;

        spin_lock_irqsave(hostdata->host->host_lock, flags);
        while (!list_empty(&hostdata->sent)) {
                evt = list_first_entry(&hostdata->sent, struct srp_event_struct, list);
                list_del(&evt->list);
                timer_delete(&evt->timer);

                spin_unlock_irqrestore(hostdata->host->host_lock, flags);
                if (evt->cmnd) {
                        evt->cmnd->result = (error_code << 16);
                        unmap_cmd_data(&evt->iu.srp.cmd, evt,
                                       evt->hostdata->dev);
                        if (evt->cmnd_done)
                                evt->cmnd_done(evt->cmnd);
                } else if (evt->done && evt->crq.format != VIOSRP_MAD_FORMAT &&
                           evt->iu.srp.login_req.opcode != SRP_LOGIN_REQ)
                        evt->done(evt);
                free_event_struct(&evt->hostdata->pool, evt);
                spin_lock_irqsave(hostdata->host->host_lock, flags);
        }
        spin_unlock_irqrestore(hostdata->host->host_lock, flags);
}

/**
 * ibmvscsi_set_request_limit - Set the adapter request_limit in response to
 * an adapter failure, reset, or SRP Login. Done under host lock to prevent
 * race with SCSI command submission.
 * @hostdata:   adapter to adjust
 * @limit:      new request limit
 */
static void ibmvscsi_set_request_limit(struct ibmvscsi_host_data *hostdata, int limit)
{
        unsigned long flags;

        spin_lock_irqsave(hostdata->host->host_lock, flags);
        atomic_set(&hostdata->request_limit, limit);
        spin_unlock_irqrestore(hostdata->host->host_lock, flags);
}

/**
 * ibmvscsi_reset_host - Reset the connection to the server
 * @hostdata:   struct ibmvscsi_host_data to reset
*/
static void ibmvscsi_reset_host(struct ibmvscsi_host_data *hostdata)
{
        scsi_block_requests(hostdata->host);
        ibmvscsi_set_request_limit(hostdata, 0);

        purge_requests(hostdata, DID_ERROR);
        hostdata->action = IBMVSCSI_HOST_ACTION_RESET;
        wake_up(&hostdata->work_wait_q);
}

/**
 * ibmvscsi_timeout - Internal command timeout handler
 * @t:  struct srp_event_struct that timed out
 *
 * Called when an internally generated command times out
*/
static void ibmvscsi_timeout(struct timer_list *t)
{
        struct srp_event_struct *evt_struct = timer_container_of(evt_struct,
                                                                 t, timer);
        struct ibmvscsi_host_data *hostdata = evt_struct->hostdata;

        dev_err(hostdata->dev, "Command timed out (%x). Resetting connection\n",
                evt_struct->iu.srp.cmd.opcode);

        ibmvscsi_reset_host(hostdata);
}


/* ------------------------------------------------------------
 * Routines for sending and receiving SRPs
 */
/**
 * ibmvscsi_send_srp_event: - Transforms event to u64 array and calls send_crq()
 * @evt_struct: evt_struct to be sent
 * @hostdata:   ibmvscsi_host_data of host
 * @timeout:    timeout in seconds - 0 means do not time command
 *
 * Returns the value returned from ibmvscsi_send_crq(). (Zero for success)
 * Note that this routine assumes that host_lock is held for synchronization
*/
static enum scsi_qc_status
ibmvscsi_send_srp_event(struct srp_event_struct *evt_struct,
                        struct ibmvscsi_host_data *hostdata,
                        unsigned long timeout)
{
        __be64 *crq_as_u64 = (__be64 *)&evt_struct->crq;
        int request_status = 0;
        int rc;
        int srp_req = 0;

        /* If we have exhausted our request limit, just fail this request,
         * unless it is for a reset or abort.
         * Note that there are rare cases involving driver generated requests 
         * (such as task management requests) that the mid layer may think we
         * can handle more requests (can_queue) when we actually can't
         */
        if (evt_struct->crq.format == VIOSRP_SRP_FORMAT) {
                srp_req = 1;
                request_status =
                        atomic_dec_if_positive(&hostdata->request_limit);
                /* If request limit was -1 when we started, it is now even
                 * less than that
                 */
                if (request_status < -1)
                        goto send_error;
                /* Otherwise, we may have run out of requests. */
                /* If request limit was 0 when we started the adapter is in the
                 * process of performing a login with the server adapter, or
                 * we may have run out of requests.
                 */
                else if (request_status == -1 &&
                         evt_struct->iu.srp.login_req.opcode != SRP_LOGIN_REQ)
                        goto send_busy;
                /* Abort and reset calls should make it through.
                 * Nothing except abort and reset should use the last two
                 * slots unless we had two or less to begin with.
                 */
                else if (request_status < 2 &&
                         evt_struct->iu.srp.cmd.opcode != SRP_TSK_MGMT) {
                        /* In the case that we have less than two requests
                         * available, check the server limit as a combination
                         * of the request limit and the number of requests
                         * in-flight (the size of the send list).  If the
                         * server limit is greater than 2, return busy so
                         * that the last two are reserved for reset and abort.
                         */
                        int server_limit = request_status;
                        struct srp_event_struct *tmp_evt;

                        list_for_each_entry(tmp_evt, &hostdata->sent, list) {
                                server_limit++;
                        }

                        if (server_limit > 2)
                                goto send_busy;
                }
        }

        /* Copy the IU into the transfer area */
        *evt_struct->xfer_iu = evt_struct->iu;
        evt_struct->xfer_iu->srp.rsp.tag = (u64)evt_struct;

        /* Add this to the sent list.  We need to do this 
         * before we actually send 
         * in case it comes back REALLY fast
         */
        list_add_tail(&evt_struct->list, &hostdata->sent);

        timer_setup(&evt_struct->timer, ibmvscsi_timeout, 0);
        if (timeout) {
                evt_struct->timer.expires = jiffies + (timeout * HZ);
                add_timer(&evt_struct->timer);
        }

        rc = ibmvscsi_send_crq(hostdata, be64_to_cpu(crq_as_u64[0]),
                               be64_to_cpu(crq_as_u64[1]));
        if (rc != 0) {
                list_del(&evt_struct->list);
                timer_delete(&evt_struct->timer);

                /* If send_crq returns H_CLOSED, return SCSI_MLQUEUE_HOST_BUSY.
                 * Firmware will send a CRQ with a transport event (0xFF) to
                 * tell this client what has happened to the transport.  This
                 * will be handled in ibmvscsi_handle_crq()
                 */
                if (rc == H_CLOSED) {
                        dev_warn(hostdata->dev, "send warning. "
                                 "Receive queue closed, will retry.\n");
                        goto send_busy;
                }
                dev_err(hostdata->dev, "send error %d\n", rc);
                if (srp_req)
                        atomic_inc(&hostdata->request_limit);
                goto send_error;
        }

        return 0;

 send_busy:
        unmap_cmd_data(&evt_struct->iu.srp.cmd, evt_struct, hostdata->dev);

        free_event_struct(&hostdata->pool, evt_struct);
        if (srp_req && request_status != -1)
                atomic_inc(&hostdata->request_limit);
        return SCSI_MLQUEUE_HOST_BUSY;

 send_error:
        unmap_cmd_data(&evt_struct->iu.srp.cmd, evt_struct, hostdata->dev);

        if (evt_struct->cmnd != NULL) {
                evt_struct->cmnd->result = DID_ERROR << 16;
                evt_struct->cmnd_done(evt_struct->cmnd);
        } else if (evt_struct->done)
                evt_struct->done(evt_struct);

        free_event_struct(&hostdata->pool, evt_struct);
        return 0;
}

/**
 * handle_cmd_rsp: -  Handle responses from commands
 * @evt_struct: srp_event_struct to be handled
 *
 * Used as a callback by when sending scsi cmds.
 * Gets called by ibmvscsi_handle_crq()
*/
static void handle_cmd_rsp(struct srp_event_struct *evt_struct)
{
        struct srp_rsp *rsp = &evt_struct->xfer_iu->srp.rsp;
        struct scsi_cmnd *cmnd = evt_struct->cmnd;

        if (unlikely(rsp->opcode != SRP_RSP)) {
                if (printk_ratelimit())
                        dev_warn(evt_struct->hostdata->dev,
                                 "bad SRP RSP type %#02x\n", rsp->opcode);
        }
        
        if (cmnd) {
                cmnd->result |= rsp->status;
                if (scsi_status_is_check_condition(cmnd->result))
                        memcpy(cmnd->sense_buffer,
                               rsp->data,
                               be32_to_cpu(rsp->sense_data_len));
                unmap_cmd_data(&evt_struct->iu.srp.cmd, 
                               evt_struct, 
                               evt_struct->hostdata->dev);

                if (rsp->flags & SRP_RSP_FLAG_DOOVER)
                        scsi_set_resid(cmnd,
                                       be32_to_cpu(rsp->data_out_res_cnt));
                else if (rsp->flags & SRP_RSP_FLAG_DIOVER)
                        scsi_set_resid(cmnd, be32_to_cpu(rsp->data_in_res_cnt));
        }

        if (evt_struct->cmnd_done)
                evt_struct->cmnd_done(cmnd);
}

/**
 * lun_from_dev: - Returns the lun of the scsi device
 * @dev:        struct scsi_device
 *
*/
static inline u16 lun_from_dev(struct scsi_device *dev)
{
        return (0x2 << 14) | (dev->id << 8) | (dev->channel << 5) | dev->lun;
}

/**
 * ibmvscsi_queuecommand_lck() - The queuecommand function of the scsi template
 * @cmnd:       struct scsi_cmnd to be executed
 * @done:       Callback function to be called when cmd is completed
*/
static enum scsi_qc_status ibmvscsi_queuecommand_lck(struct scsi_cmnd *cmnd)
{
        void (*done)(struct scsi_cmnd *) = scsi_done;
        struct srp_cmd *srp_cmd;
        struct srp_event_struct *evt_struct;
        struct srp_indirect_buf *indirect;
        struct ibmvscsi_host_data *hostdata = shost_priv(cmnd->device->host);
        u16 lun = lun_from_dev(cmnd->device);
        u8 out_fmt, in_fmt;

        cmnd->result = (DID_OK << 16);
        evt_struct = get_event_struct(&hostdata->pool);
        if (!evt_struct)
                return SCSI_MLQUEUE_HOST_BUSY;

        /* Set up the actual SRP IU */
        BUILD_BUG_ON(sizeof(evt_struct->iu.srp) != SRP_MAX_IU_LEN);
        memset(&evt_struct->iu.srp, 0x00, sizeof(evt_struct->iu.srp));
        srp_cmd = &evt_struct->iu.srp.cmd;
        srp_cmd->opcode = SRP_CMD;
        memcpy(srp_cmd->cdb, cmnd->cmnd, sizeof(srp_cmd->cdb));
        int_to_scsilun(lun, &srp_cmd->lun);

        if (!map_data_for_srp_cmd(cmnd, evt_struct, srp_cmd, hostdata->dev)) {
                if (!firmware_has_feature(FW_FEATURE_CMO))
                        sdev_printk(KERN_ERR, cmnd->device,
                                    "couldn't convert cmd to srp_cmd\n");
                free_event_struct(&hostdata->pool, evt_struct);
                return SCSI_MLQUEUE_HOST_BUSY;
        }

        init_event_struct(evt_struct,
                          handle_cmd_rsp,
                          VIOSRP_SRP_FORMAT,
                          scsi_cmd_to_rq(cmnd)->timeout / HZ);

        evt_struct->cmnd = cmnd;
        evt_struct->cmnd_done = done;

        /* Fix up dma address of the buffer itself */
        indirect = (struct srp_indirect_buf *) srp_cmd->add_data;
        out_fmt = srp_cmd->buf_fmt >> 4;
        in_fmt = srp_cmd->buf_fmt & ((1U << 4) - 1);
        if ((in_fmt == SRP_DATA_DESC_INDIRECT ||
             out_fmt == SRP_DATA_DESC_INDIRECT) &&
            indirect->table_desc.va == 0) {
                indirect->table_desc.va =
                        cpu_to_be64(be64_to_cpu(evt_struct->crq.IU_data_ptr) +
                        offsetof(struct srp_cmd, add_data) +
                        offsetof(struct srp_indirect_buf, desc_list));
        }

        return ibmvscsi_send_srp_event(evt_struct, hostdata, 0);
}

static DEF_SCSI_QCMD(ibmvscsi_queuecommand)

/* ------------------------------------------------------------
 * Routines for driver initialization
 */

/**
 * map_persist_bufs: - Pre-map persistent data for adapter logins
 * @hostdata:   ibmvscsi_host_data of host
 *
 * Map the capabilities and adapter info DMA buffers to avoid runtime failures.
 * Return 1 on error, 0 on success.
 */
static int map_persist_bufs(struct ibmvscsi_host_data *hostdata)
{

        hostdata->caps_addr = dma_map_single(hostdata->dev, &hostdata->caps,
                                             sizeof(hostdata->caps), DMA_BIDIRECTIONAL);

        if (dma_mapping_error(hostdata->dev, hostdata->caps_addr)) {
                dev_err(hostdata->dev, "Unable to map capabilities buffer!\n");
                return 1;
        }

        hostdata->adapter_info_addr = dma_map_single(hostdata->dev,
                                                     &hostdata->madapter_info,
                                                     sizeof(hostdata->madapter_info),
                                                     DMA_BIDIRECTIONAL);
        if (dma_mapping_error(hostdata->dev, hostdata->adapter_info_addr)) {
                dev_err(hostdata->dev, "Unable to map adapter info buffer!\n");
                dma_unmap_single(hostdata->dev, hostdata->caps_addr,
                                 sizeof(hostdata->caps), DMA_BIDIRECTIONAL);
                return 1;
        }

        return 0;
}

/**
 * unmap_persist_bufs: - Unmap persistent data needed for adapter logins
 * @hostdata:   ibmvscsi_host_data of host
 *
 * Unmap the capabilities and adapter info DMA buffers
 */
static void unmap_persist_bufs(struct ibmvscsi_host_data *hostdata)
{
        dma_unmap_single(hostdata->dev, hostdata->caps_addr,
                         sizeof(hostdata->caps), DMA_BIDIRECTIONAL);

        dma_unmap_single(hostdata->dev, hostdata->adapter_info_addr,
                         sizeof(hostdata->madapter_info), DMA_BIDIRECTIONAL);
}

/**
 * login_rsp: - Handle response to SRP login request
 * @evt_struct: srp_event_struct with the response
 *
 * Used as a "done" callback by when sending srp_login. Gets called
 * by ibmvscsi_handle_crq()
*/
static void login_rsp(struct srp_event_struct *evt_struct)
{
        struct ibmvscsi_host_data *hostdata = evt_struct->hostdata;
        switch (evt_struct->xfer_iu->srp.login_rsp.opcode) {
        case SRP_LOGIN_RSP:     /* it worked! */
                break;
        case SRP_LOGIN_REJ:     /* refused! */
                dev_info(hostdata->dev, "SRP_LOGIN_REJ reason %u\n",
                         evt_struct->xfer_iu->srp.login_rej.reason);
                /* Login failed.  */
                ibmvscsi_set_request_limit(hostdata, -1);
                return;
        default:
                dev_err(hostdata->dev, "Invalid login response typecode 0x%02x!\n",
                        evt_struct->xfer_iu->srp.login_rsp.opcode);
                /* Login failed.  */
                ibmvscsi_set_request_limit(hostdata, -1);
                return;
        }

        dev_info(hostdata->dev, "SRP_LOGIN succeeded\n");
        hostdata->client_migrated = 0;

        /* Now we know what the real request-limit is.
         * This value is set rather than added to request_limit because
         * request_limit could have been set to -1 by this client.
         */
        ibmvscsi_set_request_limit(hostdata,
                   be32_to_cpu(evt_struct->xfer_iu->srp.login_rsp.req_lim_delta));

        /* If we had any pending I/Os, kick them */
        hostdata->action = IBMVSCSI_HOST_ACTION_UNBLOCK;
        wake_up(&hostdata->work_wait_q);
}

/**
 * send_srp_login: - Sends the srp login
 * @hostdata:   ibmvscsi_host_data of host
 *
 * Returns zero if successful.
*/
static int send_srp_login(struct ibmvscsi_host_data *hostdata)
{
        int rc;
        unsigned long flags;
        struct srp_login_req *login;
        struct srp_event_struct *evt_struct = get_event_struct(&hostdata->pool);

        BUG_ON(!evt_struct);
        init_event_struct(evt_struct, login_rsp,
                          VIOSRP_SRP_FORMAT, login_timeout);

        login = &evt_struct->iu.srp.login_req;
        memset(login, 0, sizeof(*login));
        login->opcode = SRP_LOGIN_REQ;
        login->req_it_iu_len = cpu_to_be32(sizeof(union srp_iu));
        login->req_buf_fmt = cpu_to_be16(SRP_BUF_FORMAT_DIRECT |
                                         SRP_BUF_FORMAT_INDIRECT);

        /* Start out with a request limit of 0, since this is negotiated in
         * the login request we are just sending and login requests always
         * get sent by the driver regardless of request_limit.
         */
        ibmvscsi_set_request_limit(hostdata, 0);

        spin_lock_irqsave(hostdata->host->host_lock, flags);
        rc = ibmvscsi_send_srp_event(evt_struct, hostdata, login_timeout * 2);
        spin_unlock_irqrestore(hostdata->host->host_lock, flags);
        dev_info(hostdata->dev, "sent SRP login\n");
        return rc;
};

/**
 * capabilities_rsp: - Handle response to MAD adapter capabilities request
 * @evt_struct: srp_event_struct with the response
 *
 * Used as a "done" callback by when sending adapter_info.
 */
static void capabilities_rsp(struct srp_event_struct *evt_struct)
{
        struct ibmvscsi_host_data *hostdata = evt_struct->hostdata;

        if (evt_struct->xfer_iu->mad.capabilities.common.status) {
                dev_err(hostdata->dev, "error 0x%X getting capabilities info\n",
                        evt_struct->xfer_iu->mad.capabilities.common.status);
        } else {
                if (hostdata->caps.migration.common.server_support !=
                    cpu_to_be16(SERVER_SUPPORTS_CAP))
                        dev_info(hostdata->dev, "Partition migration not supported\n");

                if (client_reserve) {
                        if (hostdata->caps.reserve.common.server_support ==
                            cpu_to_be16(SERVER_SUPPORTS_CAP))
                                dev_info(hostdata->dev, "Client reserve enabled\n");
                        else
                                dev_info(hostdata->dev, "Client reserve not supported\n");
                }
        }

        send_srp_login(hostdata);
}

/**
 * send_mad_capabilities: - Sends the mad capabilities request
 *      and stores the result so it can be retrieved with
 * @hostdata:   ibmvscsi_host_data of host
 */
static void send_mad_capabilities(struct ibmvscsi_host_data *hostdata)
{
        struct viosrp_capabilities *req;
        struct srp_event_struct *evt_struct;
        unsigned long flags;
        struct device_node *of_node = hostdata->dev->of_node;
        const char *location;

        evt_struct = get_event_struct(&hostdata->pool);
        BUG_ON(!evt_struct);

        init_event_struct(evt_struct, capabilities_rsp,
                          VIOSRP_MAD_FORMAT, info_timeout);

        req = &evt_struct->iu.mad.capabilities;
        memset(req, 0, sizeof(*req));

        hostdata->caps.flags = cpu_to_be32(CAP_LIST_SUPPORTED);
        if (hostdata->client_migrated)
                hostdata->caps.flags |= cpu_to_be32(CLIENT_MIGRATED);

        strscpy(hostdata->caps.name, dev_name(&hostdata->host->shost_gendev),
                sizeof(hostdata->caps.name));

        location = of_get_property(of_node, "ibm,loc-code", NULL);
        location = location ? location : dev_name(hostdata->dev);
        strscpy(hostdata->caps.loc, location, sizeof(hostdata->caps.loc));

        req->common.type = cpu_to_be32(VIOSRP_CAPABILITIES_TYPE);
        req->buffer = cpu_to_be64(hostdata->caps_addr);

        hostdata->caps.migration.common.cap_type =
                                cpu_to_be32(MIGRATION_CAPABILITIES);
        hostdata->caps.migration.common.length =
                                cpu_to_be16(sizeof(hostdata->caps.migration));
        hostdata->caps.migration.common.server_support =
                                cpu_to_be16(SERVER_SUPPORTS_CAP);
        hostdata->caps.migration.ecl = cpu_to_be32(1);

        if (client_reserve) {
                hostdata->caps.reserve.common.cap_type =
                                        cpu_to_be32(RESERVATION_CAPABILITIES);
                hostdata->caps.reserve.common.length =
                                cpu_to_be16(sizeof(hostdata->caps.reserve));
                hostdata->caps.reserve.common.server_support =
                                cpu_to_be16(SERVER_SUPPORTS_CAP);
                hostdata->caps.reserve.type =
                                cpu_to_be32(CLIENT_RESERVE_SCSI_2);
                req->common.length =
                                cpu_to_be16(sizeof(hostdata->caps));
        } else
                req->common.length = cpu_to_be16(sizeof(hostdata->caps) -
                                                sizeof(hostdata->caps.reserve));

        spin_lock_irqsave(hostdata->host->host_lock, flags);
        if (ibmvscsi_send_srp_event(evt_struct, hostdata, info_timeout * 2))
                dev_err(hostdata->dev, "couldn't send CAPABILITIES_REQ!\n");
        spin_unlock_irqrestore(hostdata->host->host_lock, flags);
};

/**
 * fast_fail_rsp: - Handle response to MAD enable fast fail
 * @evt_struct: srp_event_struct with the response
 *
 * Used as a "done" callback by when sending enable fast fail. Gets called
 * by ibmvscsi_handle_crq()
 */
static void fast_fail_rsp(struct srp_event_struct *evt_struct)
{
        struct ibmvscsi_host_data *hostdata = evt_struct->hostdata;
        u16 status = be16_to_cpu(evt_struct->xfer_iu->mad.fast_fail.common.status);

        if (status == VIOSRP_MAD_NOT_SUPPORTED)
                dev_err(hostdata->dev, "fast_fail not supported in server\n");
        else if (status == VIOSRP_MAD_FAILED)
                dev_err(hostdata->dev, "fast_fail request failed\n");
        else if (status != VIOSRP_MAD_SUCCESS)
                dev_err(hostdata->dev, "error 0x%X enabling fast_fail\n", status);

        send_mad_capabilities(hostdata);
}

/**
 * enable_fast_fail() - Start host initialization
 * @hostdata:   ibmvscsi_host_data of host
 *
 * Returns zero if successful.
 */
static int enable_fast_fail(struct ibmvscsi_host_data *hostdata)
{
        int rc;
        unsigned long flags;
        struct viosrp_fast_fail *fast_fail_mad;
        struct srp_event_struct *evt_struct;

        if (!fast_fail) {
                send_mad_capabilities(hostdata);
                return 0;
        }

        evt_struct = get_event_struct(&hostdata->pool);
        BUG_ON(!evt_struct);

        init_event_struct(evt_struct, fast_fail_rsp, VIOSRP_MAD_FORMAT, info_timeout);

        fast_fail_mad = &evt_struct->iu.mad.fast_fail;
        memset(fast_fail_mad, 0, sizeof(*fast_fail_mad));
        fast_fail_mad->common.type = cpu_to_be32(VIOSRP_ENABLE_FAST_FAIL);
        fast_fail_mad->common.length = cpu_to_be16(sizeof(*fast_fail_mad));

        spin_lock_irqsave(hostdata->host->host_lock, flags);
        rc = ibmvscsi_send_srp_event(evt_struct, hostdata, info_timeout * 2);
        spin_unlock_irqrestore(hostdata->host->host_lock, flags);
        return rc;
}

/**
 * adapter_info_rsp: - Handle response to MAD adapter info request
 * @evt_struct: srp_event_struct with the response
 *
 * Used as a "done" callback by when sending adapter_info. Gets called
 * by ibmvscsi_handle_crq()
*/
static void adapter_info_rsp(struct srp_event_struct *evt_struct)
{
        struct ibmvscsi_host_data *hostdata = evt_struct->hostdata;

        if (evt_struct->xfer_iu->mad.adapter_info.common.status) {
                dev_err(hostdata->dev, "error %d getting adapter info\n",
                        evt_struct->xfer_iu->mad.adapter_info.common.status);
        } else {
                dev_info(hostdata->dev, "host srp version: %s, "
                         "host partition %s (%d), OS %d, max io %u\n",
                         hostdata->madapter_info.srp_version,
                         hostdata->madapter_info.partition_name,
                         be32_to_cpu(hostdata->madapter_info.partition_number),
                         be32_to_cpu(hostdata->madapter_info.os_type),
                         be32_to_cpu(hostdata->madapter_info.port_max_txu[0]));
                
                if (hostdata->madapter_info.port_max_txu[0]) 
                        hostdata->host->max_sectors = 
                                be32_to_cpu(hostdata->madapter_info.port_max_txu[0]) >> 9;
                
                if (be32_to_cpu(hostdata->madapter_info.os_type) == SRP_MAD_OS_AIX &&
                    strcmp(hostdata->madapter_info.srp_version, "1.6a") <= 0) {
                        dev_err(hostdata->dev, "host (Ver. %s) doesn't support large transfers\n",
                                hostdata->madapter_info.srp_version);
                        dev_err(hostdata->dev, "limiting scatterlists to %d\n",
                                MAX_INDIRECT_BUFS);
                        hostdata->host->sg_tablesize = MAX_INDIRECT_BUFS;
                }

                if (be32_to_cpu(hostdata->madapter_info.os_type) == SRP_MAD_OS_AIX) {
                        enable_fast_fail(hostdata);
                        return;
                }
        }

        send_srp_login(hostdata);
}

/**
 * send_mad_adapter_info: - Sends the mad adapter info request
 *      and stores the result so it can be retrieved with
 *      sysfs.  We COULD consider causing a failure if the
 *      returned SRP version doesn't match ours.
 * @hostdata:   ibmvscsi_host_data of host
 * 
 * Returns zero if successful.
*/
static void send_mad_adapter_info(struct ibmvscsi_host_data *hostdata)
{
        struct viosrp_adapter_info *req;
        struct srp_event_struct *evt_struct;
        unsigned long flags;

        evt_struct = get_event_struct(&hostdata->pool);
        BUG_ON(!evt_struct);

        init_event_struct(evt_struct,
                          adapter_info_rsp,
                          VIOSRP_MAD_FORMAT,
                          info_timeout);
        
        req = &evt_struct->iu.mad.adapter_info;
        memset(req, 0x00, sizeof(*req));
        
        req->common.type = cpu_to_be32(VIOSRP_ADAPTER_INFO_TYPE);
        req->common.length = cpu_to_be16(sizeof(hostdata->madapter_info));
        req->buffer = cpu_to_be64(hostdata->adapter_info_addr);

        spin_lock_irqsave(hostdata->host->host_lock, flags);
        if (ibmvscsi_send_srp_event(evt_struct, hostdata, info_timeout * 2))
                dev_err(hostdata->dev, "couldn't send ADAPTER_INFO_REQ!\n");
        spin_unlock_irqrestore(hostdata->host->host_lock, flags);
};

/*
 * init_adapter() - Start virtual adapter initialization sequence
 */
static void init_adapter(struct ibmvscsi_host_data *hostdata)
{
        send_mad_adapter_info(hostdata);
}

/*
 * sync_completion: Signal that a synchronous command has completed
 * Note that after returning from this call, the evt_struct is freed.
 * the caller waiting on this completion shouldn't touch the evt_struct
 * again.
 */
static void sync_completion(struct srp_event_struct *evt_struct)
{
        /* copy the response back */
        if (evt_struct->sync_srp)
                *evt_struct->sync_srp = *evt_struct->xfer_iu;
        
        complete(&evt_struct->comp);
}

/*
 * ibmvscsi_eh_abort_handler: Abort a command...from scsi host template
 * send this over to the server and wait synchronously for the response
 */
static int ibmvscsi_eh_abort_handler(struct scsi_cmnd *cmd)
{
        struct ibmvscsi_host_data *hostdata = shost_priv(cmd->device->host);
        struct srp_tsk_mgmt *tsk_mgmt;
        struct srp_event_struct *evt;
        struct srp_event_struct *tmp_evt, *found_evt;
        union viosrp_iu srp_rsp;
        int rsp_rc;
        unsigned long flags;
        u16 lun = lun_from_dev(cmd->device);
        unsigned long wait_switch = 0;

        /* First, find this command in our sent list so we can figure
         * out the correct tag
         */
        spin_lock_irqsave(hostdata->host->host_lock, flags);
        wait_switch = jiffies + (init_timeout * HZ);
        do {
                found_evt = NULL;
                list_for_each_entry(tmp_evt, &hostdata->sent, list) {
                        if (tmp_evt->cmnd == cmd) {
                                found_evt = tmp_evt;
                                break;
                        }
                }

                if (!found_evt) {
                        spin_unlock_irqrestore(hostdata->host->host_lock, flags);
                        return SUCCESS;
                }

                evt = get_event_struct(&hostdata->pool);
                if (evt == NULL) {
                        spin_unlock_irqrestore(hostdata->host->host_lock, flags);
                        sdev_printk(KERN_ERR, cmd->device,
                                "failed to allocate abort event\n");
                        return FAILED;
                }
        
                init_event_struct(evt,
                                  sync_completion,
                                  VIOSRP_SRP_FORMAT,
                                  abort_timeout);

                tsk_mgmt = &evt->iu.srp.tsk_mgmt;
        
                /* Set up an abort SRP command */
                memset(tsk_mgmt, 0x00, sizeof(*tsk_mgmt));
                tsk_mgmt->opcode = SRP_TSK_MGMT;
                int_to_scsilun(lun, &tsk_mgmt->lun);
                tsk_mgmt->tsk_mgmt_func = SRP_TSK_ABORT_TASK;
                tsk_mgmt->task_tag = (u64) found_evt;

                evt->sync_srp = &srp_rsp;

                init_completion(&evt->comp);
                rsp_rc = ibmvscsi_send_srp_event(evt, hostdata, abort_timeout * 2);

                if (rsp_rc != SCSI_MLQUEUE_HOST_BUSY)
                        break;

                spin_unlock_irqrestore(hostdata->host->host_lock, flags);
                msleep(10);
                spin_lock_irqsave(hostdata->host->host_lock, flags);
        } while (time_before(jiffies, wait_switch));

        spin_unlock_irqrestore(hostdata->host->host_lock, flags);

        if (rsp_rc != 0) {
                sdev_printk(KERN_ERR, cmd->device,
                            "failed to send abort() event. rc=%d\n", rsp_rc);
                return FAILED;
        }

        sdev_printk(KERN_INFO, cmd->device,
                    "aborting command. lun 0x%llx, tag 0x%llx\n",
                    (((u64) lun) << 48), (u64) found_evt);

        wait_for_completion(&evt->comp);

        /* make sure we got a good response */
        if (unlikely(srp_rsp.srp.rsp.opcode != SRP_RSP)) {
                if (printk_ratelimit())
                        sdev_printk(KERN_WARNING, cmd->device, "abort bad SRP RSP type %d\n",
                                    srp_rsp.srp.rsp.opcode);
                return FAILED;
        }

        if (srp_rsp.srp.rsp.flags & SRP_RSP_FLAG_RSPVALID)
                rsp_rc = *((int *)srp_rsp.srp.rsp.data);
        else
                rsp_rc = srp_rsp.srp.rsp.status;

        if (rsp_rc) {
                if (printk_ratelimit())
                        sdev_printk(KERN_WARNING, cmd->device,
                                    "abort code %d for task tag 0x%llx\n",
                                    rsp_rc, tsk_mgmt->task_tag);
                return FAILED;
        }

        /* Because we dropped the spinlock above, it's possible
         * The event is no longer in our list.  Make sure it didn't
         * complete while we were aborting
         */
        spin_lock_irqsave(hostdata->host->host_lock, flags);
        found_evt = NULL;
        list_for_each_entry(tmp_evt, &hostdata->sent, list) {
                if (tmp_evt->cmnd == cmd) {
                        found_evt = tmp_evt;
                        break;
                }
        }

        if (found_evt == NULL) {
                spin_unlock_irqrestore(hostdata->host->host_lock, flags);
                sdev_printk(KERN_INFO, cmd->device, "aborted task tag 0x%llx completed\n",
                            tsk_mgmt->task_tag);
                return SUCCESS;
        }

        sdev_printk(KERN_INFO, cmd->device, "successfully aborted task tag 0x%llx\n",
                    tsk_mgmt->task_tag);

        cmd->result = (DID_ABORT << 16);
        list_del(&found_evt->list);
        unmap_cmd_data(&found_evt->iu.srp.cmd, found_evt,
                       found_evt->hostdata->dev);
        free_event_struct(&found_evt->hostdata->pool, found_evt);
        spin_unlock_irqrestore(hostdata->host->host_lock, flags);
        atomic_inc(&hostdata->request_limit);
        return SUCCESS;
}

/*
 * ibmvscsi_eh_device_reset_handler: Reset a single LUN...from scsi host 
 * template send this over to the server and wait synchronously for the 
 * response
 */
static int ibmvscsi_eh_device_reset_handler(struct scsi_cmnd *cmd)
{
        struct ibmvscsi_host_data *hostdata = shost_priv(cmd->device->host);
        struct srp_tsk_mgmt *tsk_mgmt;
        struct srp_event_struct *evt;
        struct srp_event_struct *tmp_evt, *pos;
        union viosrp_iu srp_rsp;
        int rsp_rc;
        unsigned long flags;
        u16 lun = lun_from_dev(cmd->device);
        unsigned long wait_switch = 0;

        spin_lock_irqsave(hostdata->host->host_lock, flags);
        wait_switch = jiffies + (init_timeout * HZ);
        do {
                evt = get_event_struct(&hostdata->pool);
                if (evt == NULL) {
                        spin_unlock_irqrestore(hostdata->host->host_lock, flags);
                        sdev_printk(KERN_ERR, cmd->device,
                                "failed to allocate reset event\n");
                        return FAILED;
                }
        
                init_event_struct(evt,
                                  sync_completion,
                                  VIOSRP_SRP_FORMAT,
                                  reset_timeout);

                tsk_mgmt = &evt->iu.srp.tsk_mgmt;

                /* Set up a lun reset SRP command */
                memset(tsk_mgmt, 0x00, sizeof(*tsk_mgmt));
                tsk_mgmt->opcode = SRP_TSK_MGMT;
                int_to_scsilun(lun, &tsk_mgmt->lun);
                tsk_mgmt->tsk_mgmt_func = SRP_TSK_LUN_RESET;

                evt->sync_srp = &srp_rsp;

                init_completion(&evt->comp);
                rsp_rc = ibmvscsi_send_srp_event(evt, hostdata, reset_timeout * 2);

                if (rsp_rc != SCSI_MLQUEUE_HOST_BUSY)
                        break;

                spin_unlock_irqrestore(hostdata->host->host_lock, flags);
                msleep(10);
                spin_lock_irqsave(hostdata->host->host_lock, flags);
        } while (time_before(jiffies, wait_switch));

        spin_unlock_irqrestore(hostdata->host->host_lock, flags);

        if (rsp_rc != 0) {
                sdev_printk(KERN_ERR, cmd->device,
                            "failed to send reset event. rc=%d\n", rsp_rc);
                return FAILED;
        }

        sdev_printk(KERN_INFO, cmd->device, "resetting device. lun 0x%llx\n",
                    (((u64) lun) << 48));

        wait_for_completion(&evt->comp);

        /* make sure we got a good response */
        if (unlikely(srp_rsp.srp.rsp.opcode != SRP_RSP)) {
                if (printk_ratelimit())
                        sdev_printk(KERN_WARNING, cmd->device, "reset bad SRP RSP type %d\n",
                                    srp_rsp.srp.rsp.opcode);
                return FAILED;
        }

        if (srp_rsp.srp.rsp.flags & SRP_RSP_FLAG_RSPVALID)
                rsp_rc = *((int *)srp_rsp.srp.rsp.data);
        else
                rsp_rc = srp_rsp.srp.rsp.status;

        if (rsp_rc) {
                if (printk_ratelimit())
                        sdev_printk(KERN_WARNING, cmd->device,
                                    "reset code %d for task tag 0x%llx\n",
                                    rsp_rc, tsk_mgmt->task_tag);
                return FAILED;
        }

        /* We need to find all commands for this LUN that have not yet been
         * responded to, and fail them with DID_RESET
         */
        spin_lock_irqsave(hostdata->host->host_lock, flags);
        list_for_each_entry_safe(tmp_evt, pos, &hostdata->sent, list) {
                if ((tmp_evt->cmnd) && (tmp_evt->cmnd->device == cmd->device)) {
                        if (tmp_evt->cmnd)
                                tmp_evt->cmnd->result = (DID_RESET << 16);
                        list_del(&tmp_evt->list);
                        unmap_cmd_data(&tmp_evt->iu.srp.cmd, tmp_evt,
                                       tmp_evt->hostdata->dev);
                        free_event_struct(&tmp_evt->hostdata->pool,
                                                   tmp_evt);
                        atomic_inc(&hostdata->request_limit);
                        if (tmp_evt->cmnd_done)
                                tmp_evt->cmnd_done(tmp_evt->cmnd);
                        else if (tmp_evt->done)
                                tmp_evt->done(tmp_evt);
                }
        }
        spin_unlock_irqrestore(hostdata->host->host_lock, flags);
        return SUCCESS;
}

/**
 * ibmvscsi_eh_host_reset_handler - Reset the connection to the server
 * @cmd:        struct scsi_cmnd having problems
*/
static int ibmvscsi_eh_host_reset_handler(struct scsi_cmnd *cmd)
{
        unsigned long wait_switch = 0;
        struct ibmvscsi_host_data *hostdata = shost_priv(cmd->device->host);

        dev_err(hostdata->dev, "Resetting connection due to error recovery\n");

        ibmvscsi_reset_host(hostdata);

        for (wait_switch = jiffies + (init_timeout * HZ);
             time_before(jiffies, wait_switch) &&
                     atomic_read(&hostdata->request_limit) < 2;) {

                msleep(10);
        }

        if (atomic_read(&hostdata->request_limit) <= 0)
                return FAILED;

        return SUCCESS;
}

/**
 * ibmvscsi_handle_crq: - Handles and frees received events in the CRQ
 * @crq:        Command/Response queue
 * @hostdata:   ibmvscsi_host_data of host
 *
*/
static void ibmvscsi_handle_crq(struct viosrp_crq *crq,
                                struct ibmvscsi_host_data *hostdata)
{
        long rc;
        unsigned long flags;
        /* The hypervisor copies our tag value here so no byteswapping */
        struct srp_event_struct *evt_struct =
                        (__force struct srp_event_struct *)crq->IU_data_ptr;
        switch (crq->valid) {
        case VIOSRP_CRQ_INIT_RSP:               /* initialization */
                switch (crq->format) {
                case VIOSRP_CRQ_INIT:   /* Initialization message */
                        dev_info(hostdata->dev, "partner initialized\n");
                        /* Send back a response */
                        rc = ibmvscsi_send_crq(hostdata, 0xC002000000000000LL, 0);
                        if (rc == 0) {
                                /* Now login */
                                init_adapter(hostdata);
                        } else {
                                dev_err(hostdata->dev, "Unable to send init rsp. rc=%ld\n", rc);
                        }

                        break;
                case VIOSRP_CRQ_INIT_COMPLETE:  /* Initialization response */
                        dev_info(hostdata->dev, "partner initialization complete\n");

                        /* Now login */
                        init_adapter(hostdata);
                        break;
                default:
                        dev_err(hostdata->dev, "unknown crq message type: %d\n", crq->format);
                }
                return;
        case VIOSRP_CRQ_XPORT_EVENT:    /* Hypervisor telling us the connection is closed */
                scsi_block_requests(hostdata->host);
                ibmvscsi_set_request_limit(hostdata, 0);
                if (crq->format == 0x06) {
                        /* We need to re-setup the interpartition connection */
                        dev_info(hostdata->dev, "Re-enabling adapter!\n");
                        hostdata->client_migrated = 1;
                        hostdata->action = IBMVSCSI_HOST_ACTION_REENABLE;
                        purge_requests(hostdata, DID_REQUEUE);
                        wake_up(&hostdata->work_wait_q);
                } else {
                        dev_err(hostdata->dev, "Virtual adapter failed rc %d!\n",
                                crq->format);
                        ibmvscsi_reset_host(hostdata);
                }
                return;
        case VIOSRP_CRQ_CMD_RSP:                /* real payload */
                break;
        default:
                dev_err(hostdata->dev, "got an invalid message type 0x%02x\n",
                        crq->valid);
                return;
        }

        /* The only kind of payload CRQs we should get are responses to
         * things we send. Make sure this response is to something we
         * actually sent
         */
        if (!valid_event_struct(&hostdata->pool, evt_struct)) {
                dev_err(hostdata->dev, "returned correlation_token 0x%p is invalid!\n",
                       evt_struct);
                return;
        }

        if (atomic_read(&evt_struct->free)) {
                dev_err(hostdata->dev, "received duplicate correlation_token 0x%p!\n",
                        evt_struct);
                return;
        }

        if (crq->format == VIOSRP_SRP_FORMAT)
                atomic_add(be32_to_cpu(evt_struct->xfer_iu->srp.rsp.req_lim_delta),
                           &hostdata->request_limit);

        timer_delete(&evt_struct->timer);

        if ((crq->status != VIOSRP_OK && crq->status != VIOSRP_OK2) && evt_struct->cmnd)
                evt_struct->cmnd->result = DID_ERROR << 16;
        if (evt_struct->done)
                evt_struct->done(evt_struct);
        else
                dev_err(hostdata->dev, "returned done() is NULL; not running it!\n");

        /*
         * Lock the host_lock before messing with these structures, since we
         * are running in a task context
         */
        spin_lock_irqsave(evt_struct->hostdata->host->host_lock, flags);
        list_del(&evt_struct->list);
        free_event_struct(&evt_struct->hostdata->pool, evt_struct);
        spin_unlock_irqrestore(evt_struct->hostdata->host->host_lock, flags);
}

/**
 * ibmvscsi_sdev_configure: Set the "allow_restart" flag for each disk.
 * @sdev:       struct scsi_device device to configure
 * @lim:        Request queue limits
 *
 * Enable allow_restart for a device if it is a disk.  Adjust the
 * queue_depth here also as is required by the documentation for
 * struct scsi_host_template.
 */
static int ibmvscsi_sdev_configure(struct scsi_device *sdev,
                                   struct queue_limits *lim)
{
        struct Scsi_Host *shost = sdev->host;
        unsigned long lock_flags = 0;

        spin_lock_irqsave(shost->host_lock, lock_flags);
        if (sdev->type == TYPE_DISK) {
                sdev->allow_restart = 1;
                blk_queue_rq_timeout(sdev->request_queue, 120 * HZ);
        }
        spin_unlock_irqrestore(shost->host_lock, lock_flags);
        return 0;
}

/**
 * ibmvscsi_change_queue_depth - Change the device's queue depth
 * @sdev:       scsi device struct
 * @qdepth:     depth to set
 *
 * Return value:
 *      actual depth set
 **/
static int ibmvscsi_change_queue_depth(struct scsi_device *sdev, int qdepth)
{
        if (qdepth > IBMVSCSI_MAX_CMDS_PER_LUN)
                qdepth = IBMVSCSI_MAX_CMDS_PER_LUN;
        return scsi_change_queue_depth(sdev, qdepth);
}

/* ------------------------------------------------------------
 * sysfs attributes
 */
static ssize_t show_host_vhost_loc(struct device *dev,
                                   struct device_attribute *attr, char *buf)
{
        struct Scsi_Host *shost = class_to_shost(dev);
        struct ibmvscsi_host_data *hostdata = shost_priv(shost);
        int len;

        len = snprintf(buf, sizeof(hostdata->caps.loc), "%s\n",
                       hostdata->caps.loc);
        return len;
}

static struct device_attribute ibmvscsi_host_vhost_loc = {
        .attr = {
                 .name = "vhost_loc",
                 .mode = S_IRUGO,
                 },
        .show = show_host_vhost_loc,
};

static ssize_t show_host_vhost_name(struct device *dev,
                                    struct device_attribute *attr, char *buf)
{
        struct Scsi_Host *shost = class_to_shost(dev);
        struct ibmvscsi_host_data *hostdata = shost_priv(shost);
        int len;

        len = snprintf(buf, sizeof(hostdata->caps.name), "%s\n",
                       hostdata->caps.name);
        return len;
}

static struct device_attribute ibmvscsi_host_vhost_name = {
        .attr = {
                 .name = "vhost_name",
                 .mode = S_IRUGO,
                 },
        .show = show_host_vhost_name,
};

static ssize_t show_host_srp_version(struct device *dev,
                                     struct device_attribute *attr, char *buf)
{
        struct Scsi_Host *shost = class_to_shost(dev);
        struct ibmvscsi_host_data *hostdata = shost_priv(shost);
        int len;

        len = snprintf(buf, PAGE_SIZE, "%s\n",
                       hostdata->madapter_info.srp_version);
        return len;
}

static struct device_attribute ibmvscsi_host_srp_version = {
        .attr = {
                 .name = "srp_version",
                 .mode = S_IRUGO,
                 },
        .show = show_host_srp_version,
};

static ssize_t show_host_partition_name(struct device *dev,
                                        struct device_attribute *attr,
                                        char *buf)
{
        struct Scsi_Host *shost = class_to_shost(dev);
        struct ibmvscsi_host_data *hostdata = shost_priv(shost);
        int len;

        len = snprintf(buf, PAGE_SIZE, "%s\n",
                       hostdata->madapter_info.partition_name);
        return len;
}

static struct device_attribute ibmvscsi_host_partition_name = {
        .attr = {
                 .name = "partition_name",
                 .mode = S_IRUGO,
                 },
        .show = show_host_partition_name,
};

static ssize_t show_host_partition_number(struct device *dev,
                                          struct device_attribute *attr,
                                          char *buf)
{
        struct Scsi_Host *shost = class_to_shost(dev);
        struct ibmvscsi_host_data *hostdata = shost_priv(shost);
        int len;

        len = snprintf(buf, PAGE_SIZE, "%d\n",
                       be32_to_cpu(hostdata->madapter_info.partition_number));
        return len;
}

static struct device_attribute ibmvscsi_host_partition_number = {
        .attr = {
                 .name = "partition_number",
                 .mode = S_IRUGO,
                 },
        .show = show_host_partition_number,
};

static ssize_t show_host_mad_version(struct device *dev,
                                     struct device_attribute *attr, char *buf)
{
        struct Scsi_Host *shost = class_to_shost(dev);
        struct ibmvscsi_host_data *hostdata = shost_priv(shost);
        int len;

        len = snprintf(buf, PAGE_SIZE, "%d\n",
                       be32_to_cpu(hostdata->madapter_info.mad_version));
        return len;
}

static struct device_attribute ibmvscsi_host_mad_version = {
        .attr = {
                 .name = "mad_version",
                 .mode = S_IRUGO,
                 },
        .show = show_host_mad_version,
};

static ssize_t show_host_os_type(struct device *dev,
                                 struct device_attribute *attr, char *buf)
{
        struct Scsi_Host *shost = class_to_shost(dev);
        struct ibmvscsi_host_data *hostdata = shost_priv(shost);
        int len;

        len = snprintf(buf, PAGE_SIZE, "%d\n",
                       be32_to_cpu(hostdata->madapter_info.os_type));
        return len;
}

static struct device_attribute ibmvscsi_host_os_type = {
        .attr = {
                 .name = "os_type",
                 .mode = S_IRUGO,
                 },
        .show = show_host_os_type,
};

static ssize_t show_host_config(struct device *dev,
                                struct device_attribute *attr, char *buf)
{
        return 0;
}

static struct device_attribute ibmvscsi_host_config = {
        .attr = {
                .name = "config",
                .mode = S_IRUGO,
                },
        .show = show_host_config,
};

static int ibmvscsi_host_reset(struct Scsi_Host *shost, int reset_type)
{
        struct ibmvscsi_host_data *hostdata = shost_priv(shost);

        dev_info(hostdata->dev, "Initiating adapter reset!\n");
        ibmvscsi_reset_host(hostdata);

        return 0;
}

static struct attribute *ibmvscsi_host_attrs[] = {
        &ibmvscsi_host_vhost_loc.attr,
        &ibmvscsi_host_vhost_name.attr,
        &ibmvscsi_host_srp_version.attr,
        &ibmvscsi_host_partition_name.attr,
        &ibmvscsi_host_partition_number.attr,
        &ibmvscsi_host_mad_version.attr,
        &ibmvscsi_host_os_type.attr,
        &ibmvscsi_host_config.attr,
        NULL
};

ATTRIBUTE_GROUPS(ibmvscsi_host);

/* ------------------------------------------------------------
 * SCSI driver registration
 */
static struct scsi_host_template driver_template = {
        .module = THIS_MODULE,
        .name = "IBM POWER Virtual SCSI Adapter " IBMVSCSI_VERSION,
        .proc_name = "ibmvscsi",
        .queuecommand = ibmvscsi_queuecommand,
        .eh_timed_out = srp_timed_out,
        .eh_abort_handler = ibmvscsi_eh_abort_handler,
        .eh_device_reset_handler = ibmvscsi_eh_device_reset_handler,
        .eh_host_reset_handler = ibmvscsi_eh_host_reset_handler,
        .sdev_configure = ibmvscsi_sdev_configure,
        .change_queue_depth = ibmvscsi_change_queue_depth,
        .host_reset = ibmvscsi_host_reset,
        .cmd_per_lun = IBMVSCSI_CMDS_PER_LUN_DEFAULT,
        .can_queue = IBMVSCSI_MAX_REQUESTS_DEFAULT,
        .this_id = -1,
        .sg_tablesize = SG_ALL,
        .shost_groups = ibmvscsi_host_groups,
};

/**
 * ibmvscsi_get_desired_dma - Calculate IO memory desired by the driver
 *
 * @vdev: struct vio_dev for the device whose desired IO mem is to be returned
 *
 * Return value:
 *      Number of bytes of IO data the driver will need to perform well.
 */
static unsigned long ibmvscsi_get_desired_dma(struct vio_dev *vdev)
{
        /* iu_storage data allocated in initialize_event_pool */
        unsigned long desired_io = max_events * sizeof(union viosrp_iu);

        /* add io space for sg data */
        desired_io += (IBMVSCSI_MAX_SECTORS_DEFAULT * 512 *
                             IBMVSCSI_CMDS_PER_LUN_DEFAULT);

        return desired_io;
}

static void ibmvscsi_do_work(struct ibmvscsi_host_data *hostdata)
{
        unsigned long flags;
        int rc;
        char *action = "reset";

        spin_lock_irqsave(hostdata->host->host_lock, flags);
        switch (hostdata->action) {
        case IBMVSCSI_HOST_ACTION_UNBLOCK:
                rc = 0;
                break;
        case IBMVSCSI_HOST_ACTION_RESET:
                spin_unlock_irqrestore(hostdata->host->host_lock, flags);
                rc = ibmvscsi_reset_crq_queue(&hostdata->queue, hostdata);
                spin_lock_irqsave(hostdata->host->host_lock, flags);
                if (!rc)
                        rc = ibmvscsi_send_crq(hostdata, 0xC001000000000000LL, 0);
                vio_enable_interrupts(to_vio_dev(hostdata->dev));
                break;
        case IBMVSCSI_HOST_ACTION_REENABLE:
                action = "enable";
                spin_unlock_irqrestore(hostdata->host->host_lock, flags);
                rc = ibmvscsi_reenable_crq_queue(&hostdata->queue, hostdata);
                spin_lock_irqsave(hostdata->host->host_lock, flags);
                if (!rc)
                        rc = ibmvscsi_send_crq(hostdata, 0xC001000000000000LL, 0);
                break;
        case IBMVSCSI_HOST_ACTION_NONE:
        default:
                spin_unlock_irqrestore(hostdata->host->host_lock, flags);
                return;
        }

        hostdata->action = IBMVSCSI_HOST_ACTION_NONE;
        spin_unlock_irqrestore(hostdata->host->host_lock, flags);

        if (rc) {
                ibmvscsi_set_request_limit(hostdata, -1);
                dev_err(hostdata->dev, "error after %s\n", action);
        }

        scsi_unblock_requests(hostdata->host);
}

static int __ibmvscsi_work_to_do(struct ibmvscsi_host_data *hostdata)
{
        if (kthread_should_stop())
                return 1;
        switch (hostdata->action) {
        case IBMVSCSI_HOST_ACTION_NONE:
                return 0;
        case IBMVSCSI_HOST_ACTION_RESET:
        case IBMVSCSI_HOST_ACTION_REENABLE:
        case IBMVSCSI_HOST_ACTION_UNBLOCK:
        default:
                break;
        }

        return 1;
}

static int ibmvscsi_work_to_do(struct ibmvscsi_host_data *hostdata)
{
        unsigned long flags;
        int rc;

        spin_lock_irqsave(hostdata->host->host_lock, flags);
        rc = __ibmvscsi_work_to_do(hostdata);
        spin_unlock_irqrestore(hostdata->host->host_lock, flags);

        return rc;
}

static int ibmvscsi_work(void *data)
{
        struct ibmvscsi_host_data *hostdata = data;
        int rc;

        set_user_nice(current, MIN_NICE);

        while (1) {
                rc = wait_event_interruptible(hostdata->work_wait_q,
                                              ibmvscsi_work_to_do(hostdata));

                BUG_ON(rc);

                if (kthread_should_stop())
                        break;

                ibmvscsi_do_work(hostdata);
        }

        return 0;
}

/*
 * Called by bus code for each adapter
 */
static int ibmvscsi_probe(struct vio_dev *vdev, const struct vio_device_id *id)
{
        struct ibmvscsi_host_data *hostdata;
        struct Scsi_Host *host;
        struct device *dev = &vdev->dev;
        struct srp_rport_identifiers ids;
        struct srp_rport *rport;
        unsigned long wait_switch = 0;
        int rc;

        dev_set_drvdata(&vdev->dev, NULL);

        host = scsi_host_alloc(&driver_template, sizeof(*hostdata));
        if (!host) {
                dev_err(&vdev->dev, "couldn't allocate host data\n");
                goto scsi_host_alloc_failed;
        }

        host->transportt = ibmvscsi_transport_template;
        hostdata = shost_priv(host);
        memset(hostdata, 0x00, sizeof(*hostdata));
        INIT_LIST_HEAD(&hostdata->sent);
        init_waitqueue_head(&hostdata->work_wait_q);
        hostdata->host = host;
        hostdata->dev = dev;
        ibmvscsi_set_request_limit(hostdata, -1);
        hostdata->host->max_sectors = IBMVSCSI_MAX_SECTORS_DEFAULT;

        if (map_persist_bufs(hostdata)) {
                dev_err(&vdev->dev, "couldn't map persistent buffers\n");
                goto persist_bufs_failed;
        }

        hostdata->work_thread = kthread_run(ibmvscsi_work, hostdata, "%s_%d",
                                            "ibmvscsi", host->host_no);

        if (IS_ERR(hostdata->work_thread)) {
                dev_err(&vdev->dev, "couldn't initialize kthread. rc=%ld\n",
                        PTR_ERR(hostdata->work_thread));
                goto init_crq_failed;
        }

        rc = ibmvscsi_init_crq_queue(&hostdata->queue, hostdata, max_events);
        if (rc != 0 && rc != H_RESOURCE) {
                dev_err(&vdev->dev, "couldn't initialize crq. rc=%d\n", rc);
                goto kill_kthread;
        }
        if (initialize_event_pool(&hostdata->pool, max_events, hostdata) != 0) {
                dev_err(&vdev->dev, "couldn't initialize event pool\n");
                goto init_pool_failed;
        }

        host->max_lun = IBMVSCSI_MAX_LUN;
        host->max_id = max_id;
        host->max_channel = max_channel;
        host->max_cmd_len = 16;

        dev_info(dev,
                 "Maximum ID: %d Maximum LUN: %llu Maximum Channel: %d\n",
                 host->max_id, host->max_lun, host->max_channel);

        if (scsi_add_host(hostdata->host, hostdata->dev))
                goto add_host_failed;

        /* we don't have a proper target_port_id so let's use the fake one */
        memcpy(ids.port_id, hostdata->madapter_info.partition_name,
               sizeof(ids.port_id));
        ids.roles = SRP_RPORT_ROLE_TARGET;
        rport = srp_rport_add(host, &ids);
        if (IS_ERR(rport))
                goto add_srp_port_failed;

        /* Try to send an initialization message.  Note that this is allowed
         * to fail if the other end is not acive.  In that case we don't
         * want to scan
         */
        if (ibmvscsi_send_crq(hostdata, 0xC001000000000000LL, 0) == 0
            || rc == H_RESOURCE) {
                /*
                 * Wait around max init_timeout secs for the adapter to finish
                 * initializing. When we are done initializing, we will have a
                 * valid request_limit.  We don't want Linux scanning before
                 * we are ready.
                 */
                for (wait_switch = jiffies + (init_timeout * HZ);
                     time_before(jiffies, wait_switch) &&
                     atomic_read(&hostdata->request_limit) < 2;) {

                        msleep(10);
                }

                /* if we now have a valid request_limit, initiate a scan */
                if (atomic_read(&hostdata->request_limit) > 0)
                        scsi_scan_host(host);
        }

        dev_set_drvdata(&vdev->dev, hostdata);
        spin_lock(&ibmvscsi_driver_lock);
        list_add_tail(&hostdata->host_list, &ibmvscsi_head);
        spin_unlock(&ibmvscsi_driver_lock);
        return 0;

      add_srp_port_failed:
        scsi_remove_host(hostdata->host);
      add_host_failed:
        release_event_pool(&hostdata->pool, hostdata);
      init_pool_failed:
        ibmvscsi_release_crq_queue(&hostdata->queue, hostdata, max_events);
      kill_kthread:
      kthread_stop(hostdata->work_thread);
      init_crq_failed:
        unmap_persist_bufs(hostdata);
      persist_bufs_failed:
        scsi_host_put(host);
      scsi_host_alloc_failed:
        return -1;
}

static void ibmvscsi_remove(struct vio_dev *vdev)
{
        struct ibmvscsi_host_data *hostdata = dev_get_drvdata(&vdev->dev);

        srp_remove_host(hostdata->host);
        scsi_remove_host(hostdata->host);

        purge_requests(hostdata, DID_ERROR);
        release_event_pool(&hostdata->pool, hostdata);

        ibmvscsi_release_crq_queue(&hostdata->queue, hostdata,
                                        max_events);

        kthread_stop(hostdata->work_thread);
        unmap_persist_bufs(hostdata);

        spin_lock(&ibmvscsi_driver_lock);
        list_del(&hostdata->host_list);
        spin_unlock(&ibmvscsi_driver_lock);

        scsi_host_put(hostdata->host);
}

/**
 * ibmvscsi_resume: Resume from suspend
 * @dev:        device struct
 *
 * We may have lost an interrupt across suspend/resume, so kick the
 * interrupt handler
 */
static int ibmvscsi_resume(struct device *dev)
{
        struct ibmvscsi_host_data *hostdata = dev_get_drvdata(dev);
        vio_disable_interrupts(to_vio_dev(hostdata->dev));
        tasklet_schedule(&hostdata->srp_task);

        return 0;
}

/*
 * ibmvscsi_device_table: Used by vio.c to match devices in the device tree we 
 * support.
 */
static const struct vio_device_id ibmvscsi_device_table[] = {
        {"vscsi", "IBM,v-scsi"},
        { "", "" }
};
MODULE_DEVICE_TABLE(vio, ibmvscsi_device_table);

static const struct dev_pm_ops ibmvscsi_pm_ops = {
        .resume = ibmvscsi_resume
};

static struct vio_driver ibmvscsi_driver = {
        .id_table = ibmvscsi_device_table,
        .probe = ibmvscsi_probe,
        .remove = ibmvscsi_remove,
        .get_desired_dma = ibmvscsi_get_desired_dma,
        .name = "ibmvscsi",
        .pm = &ibmvscsi_pm_ops,
};

static struct srp_function_template ibmvscsi_transport_functions = {
};

static int __init ibmvscsi_module_init(void)
{
        int ret;

        /* Ensure we have two requests to do error recovery */
        driver_template.can_queue = max_requests;
        max_events = max_requests + 2;

        if (!firmware_has_feature(FW_FEATURE_VIO))
                return -ENODEV;

        ibmvscsi_transport_template =
                srp_attach_transport(&ibmvscsi_transport_functions);
        if (!ibmvscsi_transport_template)
                return -ENOMEM;

        ret = vio_register_driver(&ibmvscsi_driver);
        if (ret)
                srp_release_transport(ibmvscsi_transport_template);
        return ret;
}

static void __exit ibmvscsi_module_exit(void)
{
        vio_unregister_driver(&ibmvscsi_driver);
        srp_release_transport(ibmvscsi_transport_template);
}

module_init(ibmvscsi_module_init);
module_exit(ibmvscsi_module_exit);