/*
 *  hosts.c Copyright (C) 1992 Drew Eckhardt
 *          Copyright (C) 1993, 1994, 1995 Eric Youngdale
 *          Copyright (C) 2002-2003 Christoph Hellwig
 *
 *  mid to lowlevel SCSI driver interface
 *      Initial versions: Drew Eckhardt
 *      Subsequent revisions: Eric Youngdale
 *
 *  <drew@colorado.edu>
 *
 *  Jiffies wrap fixes (host->resetting), 3 Dec 1998 Andrea Arcangeli
 *  Added QLOGIC QLA1280 SCSI controller kernel host support. 
 *     August 4, 1999 Fred Lewis, Intel DuPont
 *
 *  Updated to reflect the new initialization scheme for the higher 
 *  level of scsi drivers (sd/sr/st)
 *  September 17, 2000 Torben Mathiasen <tmm@image.dk>
 *
 *  Restructured scsi_host lists and associated functions.
 *  September 04, 2002 Mike Anderson (andmike@us.ibm.com)
 */

#include <linux/module.h>
#include <linux/blkdev.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/kthread.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/completion.h>
#include <linux/transport_class.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/idr.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_transport.h>

#include "scsi_priv.h"
#include "scsi_logging.h"


static DEFINE_IDA(host_index_ida);


static void scsi_host_cls_release(struct device *dev)
{
        put_device(&class_to_shost(dev)->shost_gendev);
}

static struct class shost_class = {
        .name           = "scsi_host",
        .dev_release    = scsi_host_cls_release,
};

/**
 *      scsi_host_set_state - Take the given host through the host state model.
 *      @shost: scsi host to change the state of.
 *      @state: state to change to.
 *
 *      Returns zero if unsuccessful or an error if the requested
 *      transition is illegal.
 **/
int scsi_host_set_state(struct Scsi_Host *shost, enum scsi_host_state state)
{
        enum scsi_host_state oldstate = shost->shost_state;

        if (state == oldstate)
                return 0;

        switch (state) {
        case SHOST_CREATED:
                /* There are no legal states that come back to
                 * created.  This is the manually initialised start
                 * state */
                goto illegal;

        case SHOST_RUNNING:
                switch (oldstate) {
                case SHOST_CREATED:
                case SHOST_RECOVERY:
                        break;
                default:
                        goto illegal;
                }
                break;

        case SHOST_RECOVERY:
                switch (oldstate) {
                case SHOST_RUNNING:
                        break;
                default:
                        goto illegal;
                }
                break;

        case SHOST_CANCEL:
                switch (oldstate) {
                case SHOST_CREATED:
                case SHOST_RUNNING:
                case SHOST_CANCEL_RECOVERY:
                        break;
                default:
                        goto illegal;
                }
                break;

        case SHOST_DEL:
                switch (oldstate) {
                case SHOST_CANCEL:
                case SHOST_DEL_RECOVERY:
                        break;
                default:
                        goto illegal;
                }
                break;

        case SHOST_CANCEL_RECOVERY:
                switch (oldstate) {
                case SHOST_CANCEL:
                case SHOST_RECOVERY:
                        break;
                default:
                        goto illegal;
                }
                break;

        case SHOST_DEL_RECOVERY:
                switch (oldstate) {
                case SHOST_CANCEL_RECOVERY:
                        break;
                default:
                        goto illegal;
                }
                break;
        }
        shost->shost_state = state;
        return 0;

 illegal:
        SCSI_LOG_ERROR_RECOVERY(1,
                                shost_printk(KERN_ERR, shost,
                                             "Illegal host state transition"
                                             "%s->%s\n",
                                             scsi_host_state_name(oldstate),
                                             scsi_host_state_name(state)));
        return -EINVAL;
}
EXPORT_SYMBOL(scsi_host_set_state);

/**
 * scsi_remove_host - remove a scsi host
 * @shost:      a pointer to a scsi host to remove
 **/
void scsi_remove_host(struct Scsi_Host *shost)
{
        unsigned long flags;

        mutex_lock(&shost->scan_mutex);
        spin_lock_irqsave(shost->host_lock, flags);
        if (scsi_host_set_state(shost, SHOST_CANCEL))
                if (scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY)) {
                        spin_unlock_irqrestore(shost->host_lock, flags);
                        mutex_unlock(&shost->scan_mutex);
                        return;
                }
        spin_unlock_irqrestore(shost->host_lock, flags);

        scsi_autopm_get_host(shost);
        flush_workqueue(shost->tmf_work_q);
        scsi_forget_host(shost);
        mutex_unlock(&shost->scan_mutex);
        scsi_proc_host_rm(shost);

        spin_lock_irqsave(shost->host_lock, flags);
        if (scsi_host_set_state(shost, SHOST_DEL))
                BUG_ON(scsi_host_set_state(shost, SHOST_DEL_RECOVERY));
        spin_unlock_irqrestore(shost->host_lock, flags);

        transport_unregister_device(&shost->shost_gendev);
        device_unregister(&shost->shost_dev);
        device_del(&shost->shost_gendev);
}
EXPORT_SYMBOL(scsi_remove_host);

/**
 * scsi_add_host_with_dma - add a scsi host with dma device
 * @shost:      scsi host pointer to add
 * @dev:        a struct device of type scsi class
 * @dma_dev:    dma device for the host
 *
 * Note: You rarely need to worry about this unless you're in a
 * virtualised host environments, so use the simpler scsi_add_host()
 * function instead.
 *
 * Return value: 
 *      0 on success / != 0 for error
 **/
int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev,
                           struct device *dma_dev)
{
        struct scsi_host_template *sht = shost->hostt;
        int error = -EINVAL;

        shost_printk(KERN_INFO, shost, "%s\n",
                        sht->info ? sht->info(shost) : sht->name);

        if (!shost->can_queue) {
                shost_printk(KERN_ERR, shost,
                             "can_queue = 0 no longer supported\n");
                goto fail;
        }

        error = scsi_init_sense_cache(shost);
        if (error)
                goto fail;

        if (shost_use_blk_mq(shost)) {
                error = scsi_mq_setup_tags(shost);
                if (error)
                        goto fail;
        } else {
                shost->bqt = blk_init_tags(shost->can_queue,
                                shost->hostt->tag_alloc_policy);
                if (!shost->bqt) {
                        error = -ENOMEM;
                        goto fail;
                }
        }

        if (!shost->shost_gendev.parent)
                shost->shost_gendev.parent = dev ? dev : &platform_bus;
        if (!dma_dev)
                dma_dev = shost->shost_gendev.parent;

        shost->dma_dev = dma_dev;

        /*
         * Increase usage count temporarily here so that calling
         * scsi_autopm_put_host() will trigger runtime idle if there is
         * nothing else preventing suspending the device.
         */
        pm_runtime_get_noresume(&shost->shost_gendev);
        pm_runtime_set_active(&shost->shost_gendev);
        pm_runtime_enable(&shost->shost_gendev);
        device_enable_async_suspend(&shost->shost_gendev);

        error = device_add(&shost->shost_gendev);
        if (error)
                goto out_disable_runtime_pm;

        scsi_host_set_state(shost, SHOST_RUNNING);
        get_device(shost->shost_gendev.parent);

        device_enable_async_suspend(&shost->shost_dev);

        error = device_add(&shost->shost_dev);
        if (error)
                goto out_del_gendev;

        get_device(&shost->shost_gendev);

        if (shost->transportt->host_size) {
                shost->shost_data = kzalloc(shost->transportt->host_size,
                                         GFP_KERNEL);
                if (shost->shost_data == NULL) {
                        error = -ENOMEM;
                        goto out_del_dev;
                }
        }

        if (shost->transportt->create_work_queue) {
                snprintf(shost->work_q_name, sizeof(shost->work_q_name),
                         "scsi_wq_%d", shost->host_no);
                shost->work_q = create_singlethread_workqueue(
                                        shost->work_q_name);
                if (!shost->work_q) {
                        error = -EINVAL;
                        goto out_free_shost_data;
                }
        }

        error = scsi_sysfs_add_host(shost);
        if (error)
                goto out_destroy_host;

        scsi_proc_host_add(shost);
        scsi_autopm_put_host(shost);
        return error;

 out_destroy_host:
        if (shost->work_q)
                destroy_workqueue(shost->work_q);
 out_free_shost_data:
        kfree(shost->shost_data);
 out_del_dev:
        device_del(&shost->shost_dev);
 out_del_gendev:
        device_del(&shost->shost_gendev);
 out_disable_runtime_pm:
        device_disable_async_suspend(&shost->shost_gendev);
        pm_runtime_disable(&shost->shost_gendev);
        pm_runtime_set_suspended(&shost->shost_gendev);
        pm_runtime_put_noidle(&shost->shost_gendev);
        if (shost_use_blk_mq(shost))
                scsi_mq_destroy_tags(shost);
 fail:
        return error;
}
EXPORT_SYMBOL(scsi_add_host_with_dma);

static void scsi_host_dev_release(struct device *dev)
{
        struct Scsi_Host *shost = dev_to_shost(dev);
        struct device *parent = dev->parent;

        scsi_proc_hostdir_rm(shost->hostt);

        /* Wait for functions invoked through call_rcu(&shost->rcu, ...) */
        rcu_barrier();

        if (shost->tmf_work_q)
                destroy_workqueue(shost->tmf_work_q);
        if (shost->ehandler)
                kthread_stop(shost->ehandler);
        if (shost->work_q)
                destroy_workqueue(shost->work_q);

        if (shost->shost_state == SHOST_CREATED) {
                /*
                 * Free the shost_dev device name here if scsi_host_alloc()
                 * and scsi_host_put() have been called but neither
                 * scsi_host_add() nor scsi_host_remove() has been called.
                 * This avoids that the memory allocated for the shost_dev
                 * name is leaked.
                 */
                kfree(dev_name(&shost->shost_dev));
        }

        if (shost_use_blk_mq(shost)) {
                if (shost->tag_set.tags)
                        scsi_mq_destroy_tags(shost);
        } else {
                if (shost->bqt)
                        blk_free_tags(shost->bqt);
        }

        kfree(shost->shost_data);

        ida_simple_remove(&host_index_ida, shost->host_no);

        if (parent)
                put_device(parent);
        kfree(shost);
}

static int shost_eh_deadline = -1;

module_param_named(eh_deadline, shost_eh_deadline, int, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(eh_deadline,
                 "SCSI EH timeout in seconds (should be between 0 and 2^31-1)");

static struct device_type scsi_host_type = {
        .name =         "scsi_host",
        .release =      scsi_host_dev_release,
};

/**
 * scsi_host_alloc - register a scsi host adapter instance.
 * @sht:        pointer to scsi host template
 * @privsize:   extra bytes to allocate for driver
 *
 * Note:
 *      Allocate a new Scsi_Host and perform basic initialization.
 *      The host is not published to the scsi midlayer until scsi_add_host
 *      is called.
 *
 * Return value:
 *      Pointer to a new Scsi_Host
 **/
struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
{
        struct Scsi_Host *shost;
        gfp_t gfp_mask = GFP_KERNEL;
        int index;

        if (sht->unchecked_isa_dma && privsize)
                gfp_mask |= __GFP_DMA;

        shost = kzalloc(sizeof(struct Scsi_Host) + privsize, gfp_mask);
        if (!shost)
                return NULL;

        shost->host_lock = &shost->default_lock;
        spin_lock_init(shost->host_lock);
        shost->shost_state = SHOST_CREATED;
        INIT_LIST_HEAD(&shost->__devices);
        INIT_LIST_HEAD(&shost->__targets);
        INIT_LIST_HEAD(&shost->eh_cmd_q);
        INIT_LIST_HEAD(&shost->starved_list);
        init_waitqueue_head(&shost->host_wait);
        mutex_init(&shost->scan_mutex);

        index = ida_simple_get(&host_index_ida, 0, 0, GFP_KERNEL);
        if (index < 0)
                goto fail_kfree;
        shost->host_no = index;

        shost->dma_channel = 0xff;

        /* These three are default values which can be overridden */
        shost->max_channel = 0;
        shost->max_id = 8;
        shost->max_lun = 8;

        /* Give each shost a default transportt */
        shost->transportt = &blank_transport_template;

        /*
         * All drivers right now should be able to handle 12 byte
         * commands.  Every so often there are requests for 16 byte
         * commands, but individual low-level drivers need to certify that
         * they actually do something sensible with such commands.
         */
        shost->max_cmd_len = 12;
        shost->hostt = sht;
        shost->this_id = sht->this_id;
        shost->can_queue = sht->can_queue;
        shost->sg_tablesize = sht->sg_tablesize;
        shost->sg_prot_tablesize = sht->sg_prot_tablesize;
        shost->cmd_per_lun = sht->cmd_per_lun;
        shost->unchecked_isa_dma = sht->unchecked_isa_dma;
        shost->use_clustering = sht->use_clustering;
        shost->no_write_same = sht->no_write_same;

        if (shost_eh_deadline == -1 || !sht->eh_host_reset_handler)
                shost->eh_deadline = -1;
        else if ((ulong) shost_eh_deadline * HZ > INT_MAX) {
                shost_printk(KERN_WARNING, shost,
                             "eh_deadline %u too large, setting to %u\n",
                             shost_eh_deadline, INT_MAX / HZ);
                shost->eh_deadline = INT_MAX;
        } else
                shost->eh_deadline = shost_eh_deadline * HZ;

        if (sht->supported_mode == MODE_UNKNOWN)
                /* means we didn't set it ... default to INITIATOR */
                shost->active_mode = MODE_INITIATOR;
        else
                shost->active_mode = sht->supported_mode;

        if (sht->max_host_blocked)
                shost->max_host_blocked = sht->max_host_blocked;
        else
                shost->max_host_blocked = SCSI_DEFAULT_HOST_BLOCKED;

        /*
         * If the driver imposes no hard sector transfer limit, start at
         * machine infinity initially.
         */
        if (sht->max_sectors)
                shost->max_sectors = sht->max_sectors;
        else
                shost->max_sectors = SCSI_DEFAULT_MAX_SECTORS;

        /*
         * assume a 4GB boundary, if not set
         */
        if (sht->dma_boundary)
                shost->dma_boundary = sht->dma_boundary;
        else
                shost->dma_boundary = 0xffffffff;

        shost->use_blk_mq = scsi_use_blk_mq;
        shost->use_blk_mq = scsi_use_blk_mq || shost->hostt->force_blk_mq;

        device_initialize(&shost->shost_gendev);
        dev_set_name(&shost->shost_gendev, "host%d", shost->host_no);
        shost->shost_gendev.bus = &scsi_bus_type;
        shost->shost_gendev.type = &scsi_host_type;

        device_initialize(&shost->shost_dev);
        shost->shost_dev.parent = &shost->shost_gendev;
        shost->shost_dev.class = &shost_class;
        dev_set_name(&shost->shost_dev, "host%d", shost->host_no);
        shost->shost_dev.groups = scsi_sysfs_shost_attr_groups;

        shost->ehandler = kthread_run(scsi_error_handler, shost,
                        "scsi_eh_%d", shost->host_no);
        if (IS_ERR(shost->ehandler)) {
                shost_printk(KERN_WARNING, shost,
                        "error handler thread failed to spawn, error = %ld\n",
                        PTR_ERR(shost->ehandler));
                goto fail_index_remove;
        }

        shost->tmf_work_q = alloc_workqueue("scsi_tmf_%d",
                                            WQ_UNBOUND | WQ_MEM_RECLAIM,
                                           1, shost->host_no);
        if (!shost->tmf_work_q) {
                shost_printk(KERN_WARNING, shost,
                             "failed to create tmf workq\n");
                goto fail_kthread;
        }
        scsi_proc_hostdir_add(shost->hostt);
        return shost;

 fail_kthread:
        kthread_stop(shost->ehandler);
 fail_index_remove:
        ida_simple_remove(&host_index_ida, shost->host_no);
 fail_kfree:
        kfree(shost);
        return NULL;
}
EXPORT_SYMBOL(scsi_host_alloc);

struct Scsi_Host *scsi_register(struct scsi_host_template *sht, int privsize)
{
        struct Scsi_Host *shost = scsi_host_alloc(sht, privsize);

        if (!sht->detect) {
                printk(KERN_WARNING "scsi_register() called on new-style "
                                    "template for driver %s\n", sht->name);
                dump_stack();
        }

        if (shost)
                list_add_tail(&shost->sht_legacy_list, &sht->legacy_hosts);
        return shost;
}
EXPORT_SYMBOL(scsi_register);

void scsi_unregister(struct Scsi_Host *shost)
{
        list_del(&shost->sht_legacy_list);
        scsi_host_put(shost);
}
EXPORT_SYMBOL(scsi_unregister);

static int __scsi_host_match(struct device *dev, const void *data)
{
        struct Scsi_Host *p;
        const unsigned short *hostnum = data;

        p = class_to_shost(dev);
        return p->host_no == *hostnum;
}

/**
 * scsi_host_lookup - get a reference to a Scsi_Host by host no
 * @hostnum:    host number to locate
 *
 * Return value:
 *      A pointer to located Scsi_Host or NULL.
 *
 *      The caller must do a scsi_host_put() to drop the reference
 *      that scsi_host_get() took. The put_device() below dropped
 *      the reference from class_find_device().
 **/
struct Scsi_Host *scsi_host_lookup(unsigned short hostnum)
{
        struct device *cdev;
        struct Scsi_Host *shost = NULL;

        cdev = class_find_device(&shost_class, NULL, &hostnum,
                                 __scsi_host_match);
        if (cdev) {
                shost = scsi_host_get(class_to_shost(cdev));
                put_device(cdev);
        }
        return shost;
}
EXPORT_SYMBOL(scsi_host_lookup);

/**
 * scsi_host_get - inc a Scsi_Host ref count
 * @shost:      Pointer to Scsi_Host to inc.
 **/
struct Scsi_Host *scsi_host_get(struct Scsi_Host *shost)
{
        if ((shost->shost_state == SHOST_DEL) ||
                !get_device(&shost->shost_gendev))
                return NULL;
        return shost;
}
EXPORT_SYMBOL(scsi_host_get);

/**
 * scsi_host_put - dec a Scsi_Host ref count
 * @shost:      Pointer to Scsi_Host to dec.
 **/
void scsi_host_put(struct Scsi_Host *shost)
{
        put_device(&shost->shost_gendev);
}
EXPORT_SYMBOL(scsi_host_put);

int scsi_init_hosts(void)
{
        return class_register(&shost_class);
}

void scsi_exit_hosts(void)
{
        class_unregister(&shost_class);
        ida_destroy(&host_index_ida);
}

int scsi_is_host_device(const struct device *dev)
{
        return dev->type == &scsi_host_type;
}
EXPORT_SYMBOL(scsi_is_host_device);

/**
 * scsi_queue_work - Queue work to the Scsi_Host workqueue.
 * @shost:      Pointer to Scsi_Host.
 * @work:       Work to queue for execution.
 *
 * Return value:
 *      1 - work queued for execution
 *      0 - work is already queued
 *      -EINVAL - work queue doesn't exist
 **/
int scsi_queue_work(struct Scsi_Host *shost, struct work_struct *work)
{
        if (unlikely(!shost->work_q)) {
                shost_printk(KERN_ERR, shost,
                        "ERROR: Scsi host '%s' attempted to queue scsi-work, "
                        "when no workqueue created.\n", shost->hostt->name);
                dump_stack();

                return -EINVAL;
        }

        return queue_work(shost->work_q, work);
}
EXPORT_SYMBOL_GPL(scsi_queue_work);

/**
 * scsi_flush_work - Flush a Scsi_Host's workqueue.
 * @shost:      Pointer to Scsi_Host.
 **/
void scsi_flush_work(struct Scsi_Host *shost)
{
        if (!shost->work_q) {
                shost_printk(KERN_ERR, shost,
                        "ERROR: Scsi host '%s' attempted to flush scsi-work, "
                        "when no workqueue created.\n", shost->hostt->name);
                dump_stack();
                return;
        }

        flush_workqueue(shost->work_q);
}
EXPORT_SYMBOL_GPL(scsi_flush_work);