tape_core.c

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/*
 *    basic function of the tape device driver
 *
 *  S390 and zSeries version
 *    Copyright IBM Corp. 2001, 2009
 *    Author(s): Carsten Otte <[email protected]>
 *       Michael Holzheu <[email protected]>
 *       Tuan Ngo-Anh <[email protected]>
 *       Martin Schwidefsky <[email protected]>
 *       Stefan Bader <[email protected]>
 */

#define KMSG_COMPONENT "tape"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/module.h>
#include <linux/init.h>      // for kernel parameters
#include <linux/kmod.h>      // for requesting modules
#include <linux/spinlock.h>  // for locks
#include <linux/vmalloc.h>
#include <linux/list.h>
#include <linux/slab.h>

#include <asm/types.h>       // for variable types

#define TAPE_DBF_AREA   tape_core_dbf

#include "tape.h"
#include "tape_std.h"

#define LONG_BUSY_TIMEOUT 180 /* seconds */

static void __tape_do_irq (struct ccw_device *, unsigned long, struct irb *);
static void tape_delayed_next_request(struct work_struct *);
static void tape_long_busy_timeout(unsigned long data);

/*
 * One list to contain all tape devices of all disciplines, so
 * we can assign the devices to minor numbers of the same major
 * The list is protected by the rwlock
 */
static LIST_HEAD(tape_device_list);
static DEFINE_RWLOCK(tape_device_lock);

/*
 * Pointer to debug area.
 */
debug_info_t *TAPE_DBF_AREA = NULL;
EXPORT_SYMBOL(TAPE_DBF_AREA);

/*
 * Printable strings for tape enumerations.
 */
const char *tape_state_verbose[TS_SIZE] =
{
    [TS_UNUSED]   = "UNUSED",
    [TS_IN_USE]   = "IN_USE",
    [TS_BLKUSE]   = "BLKUSE",
    [TS_INIT]     = "INIT  ",
    [TS_NOT_OPER] = "NOT_OP"
};

const char *tape_op_verbose[TO_SIZE] =
{
    [TO_BLOCK] = "BLK", [TO_BSB] = "BSB",
    [TO_BSF] = "BSF",   [TO_DSE] = "DSE",
    [TO_FSB] = "FSB",   [TO_FSF] = "FSF",
    [TO_LBL] = "LBL",   [TO_NOP] = "NOP",
    [TO_RBA] = "RBA",   [TO_RBI] = "RBI",
    [TO_RFO] = "RFO",   [TO_REW] = "REW",
    [TO_RUN] = "RUN",   [TO_WRI] = "WRI",
    [TO_WTM] = "WTM",   [TO_MSEN] = "MSN",
    [TO_LOAD] = "LOA",  [TO_READ_CONFIG] = "RCF",
    [TO_READ_ATTMSG] = "RAT",
    [TO_DIS] = "DIS",   [TO_ASSIGN] = "ASS",
    [TO_UNASSIGN] = "UAS",  [TO_CRYPT_ON] = "CON",
    [TO_CRYPT_OFF] = "COF", [TO_KEKL_SET] = "KLS",
    [TO_KEKL_QUERY] = "KLQ",[TO_RDC] = "RDC",
};

static int devid_to_int(struct ccw_dev_id *dev_id)
{
    return dev_id->devno + (dev_id->ssid << 16);
}

/*
 * Some channel attached tape specific attributes.
 *
 * FIXME: In the future the first_minor and blocksize attribute should be
 *        replaced by a link to the cdev tree.
 */
static ssize_t
tape_medium_state_show(struct device *dev, struct device_attribute *attr, char *buf)
{
    struct tape_device *tdev;

    tdev = dev_get_drvdata(dev);
    return scnprintf(buf, PAGE_SIZE, "%i\n", tdev->medium_state);
}

static
DEVICE_ATTR(medium_state, 0444, tape_medium_state_show, NULL);

static ssize_t
tape_first_minor_show(struct device *dev, struct device_attribute *attr, char *buf)
{
    struct tape_device *tdev;

    tdev = dev_get_drvdata(dev);
    return scnprintf(buf, PAGE_SIZE, "%i\n", tdev->first_minor);
}

static
DEVICE_ATTR(first_minor, 0444, tape_first_minor_show, NULL);

static ssize_t
tape_state_show(struct device *dev, struct device_attribute *attr, char *buf)
{
    struct tape_device *tdev;

    tdev = dev_get_drvdata(dev);
    return scnprintf(buf, PAGE_SIZE, "%s\n", (tdev->first_minor < 0) ?
        "OFFLINE" : tape_state_verbose[tdev->tape_state]);
}

static
DEVICE_ATTR(state, 0444, tape_state_show, NULL);

static ssize_t
tape_operation_show(struct device *dev, struct device_attribute *attr, char *buf)
{
    struct tape_device *tdev;
    ssize_t rc;

    tdev = dev_get_drvdata(dev);
    if (tdev->first_minor < 0)
        return scnprintf(buf, PAGE_SIZE, "N/A\n");

    spin_lock_irq(get_ccwdev_lock(tdev->cdev));
    if (list_empty(&tdev->req_queue))
        rc = scnprintf(buf, PAGE_SIZE, "---\n");
    else {
        struct tape_request *req;

        req = list_entry(tdev->req_queue.next, struct tape_request,
            list);
        rc = scnprintf(buf,PAGE_SIZE, "%s\n", tape_op_verbose[req->op]);
    }
    spin_unlock_irq(get_ccwdev_lock(tdev->cdev));
    return rc;
}

static
DEVICE_ATTR(operation, 0444, tape_operation_show, NULL);

static ssize_t
tape_blocksize_show(struct device *dev, struct device_attribute *attr, char *buf)
{
    struct tape_device *tdev;

    tdev = dev_get_drvdata(dev);

    return scnprintf(buf, PAGE_SIZE, "%i\n", tdev->char_data.block_size);
}

static
DEVICE_ATTR(blocksize, 0444, tape_blocksize_show, NULL);

static struct attribute *tape_attrs[] = {
    &dev_attr_medium_state.attr,
    &dev_attr_first_minor.attr,
    &dev_attr_state.attr,
    &dev_attr_operation.attr,
    &dev_attr_blocksize.attr,
    NULL
};

static struct attribute_group tape_attr_group = {
    .attrs = tape_attrs,
};

/*
 * Tape state functions
 */
void
tape_state_set(struct tape_device *device, enum tape_state newstate)
{
    const char *str;

    if (device->tape_state == TS_NOT_OPER) {
        DBF_EVENT(3, "ts_set err: not oper\n");
        return;
    }
    DBF_EVENT(4, "ts. dev:  %x\n", device->first_minor);
    DBF_EVENT(4, "old ts:\t\n");
    if (device->tape_state < TS_SIZE && device->tape_state >=0 )
        str = tape_state_verbose[device->tape_state];
    else
        str = "UNKNOWN TS";
    DBF_EVENT(4, "%s\n", str);
    DBF_EVENT(4, "new ts:\t\n");
    if (newstate < TS_SIZE && newstate >= 0)
        str = tape_state_verbose[newstate];
    else
        str = "UNKNOWN TS";
    DBF_EVENT(4, "%s\n", str);
    device->tape_state = newstate;
    wake_up(&device->state_change_wq);
}

struct tape_med_state_work_data {
    struct tape_device *device;
    enum tape_medium_state state;
    struct work_struct  work;
};

static void
tape_med_state_work_handler(struct work_struct *work)
{
    static char env_state_loaded[] = "MEDIUM_STATE=LOADED";
    static char env_state_unloaded[] = "MEDIUM_STATE=UNLOADED";
    struct tape_med_state_work_data *p =
        container_of(work, struct tape_med_state_work_data, work);
    struct tape_device *device = p->device;
    char *envp[] = { NULL, NULL };

    switch (p->state) {
    case MS_UNLOADED:
        pr_info("%s: The tape cartridge has been successfully "
            "unloaded\n", dev_name(&device->cdev->dev));
        envp[0] = env_state_unloaded;
        kobject_uevent_env(&device->cdev->dev.kobj, KOBJ_CHANGE, envp);
        break;
    case MS_LOADED:
        pr_info("%s: A tape cartridge has been mounted\n",
            dev_name(&device->cdev->dev));
        envp[0] = env_state_loaded;
        kobject_uevent_env(&device->cdev->dev.kobj, KOBJ_CHANGE, envp);
        break;
    default:
        break;
    }
    tape_put_device(device);
    kfree(p);
}

static void
tape_med_state_work(struct tape_device *device, enum tape_medium_state state)
{
    struct tape_med_state_work_data *p;

    p = kzalloc(sizeof(*p), GFP_ATOMIC);
    if (p) {
        INIT_WORK(&p->work, tape_med_state_work_handler);
        p->device = tape_get_device(device);
        p->state = state;
        schedule_work(&p->work);
    }
}

void
tape_med_state_set(struct tape_device *device, enum tape_medium_state newstate)
{
    enum tape_medium_state oldstate;

    oldstate = device->medium_state;
    if (oldstate == newstate)
        return;
    device->medium_state = newstate;
    switch(newstate){
    case MS_UNLOADED:
        device->tape_generic_status |= GMT_DR_OPEN(~0);
        if (oldstate == MS_LOADED)
            tape_med_state_work(device, MS_UNLOADED);
        break;
    case MS_LOADED:
        device->tape_generic_status &= ~GMT_DR_OPEN(~0);
        if (oldstate == MS_UNLOADED)
            tape_med_state_work(device, MS_LOADED);
        break;
    default:
        break;
    }
    wake_up(&device->state_change_wq);
}

/*
 * Stop running ccw. Has to be called with the device lock held.
 */
static int
__tape_cancel_io(struct tape_device *device, struct tape_request *request)
{
    int retries;
    int rc;

    /* Check if interrupt has already been processed */
    if (request->callback == NULL)
        return 0;

    rc = 0;
    for (retries = 0; retries < 5; retries++) {
        rc = ccw_device_clear(device->cdev, (long) request);

        switch (rc) {
            case 0:
                request->status = TAPE_REQUEST_DONE;
                return 0;
            case -EBUSY:
                request->status = TAPE_REQUEST_CANCEL;
                schedule_delayed_work(&device->tape_dnr, 0);
                return 0;
            case -ENODEV:
                DBF_EXCEPTION(2, "device gone, retry\n");
                break;
            case -EIO:
                DBF_EXCEPTION(2, "I/O error, retry\n");
                break;
            default:
                BUG();
        }
    }

    return rc;
}

/*
 * Add device into the sorted list, giving it the first
 * available minor number.
 */
static int
tape_assign_minor(struct tape_device *device)
{
    struct tape_device *tmp;
    int minor;

    minor = 0;
    write_lock(&tape_device_lock);
    list_for_each_entry(tmp, &tape_device_list, node) {
        if (minor < tmp->first_minor)
            break;
        minor += TAPE_MINORS_PER_DEV;
    }
    if (minor >= 256) {
        write_unlock(&tape_device_lock);
        return -ENODEV;
    }
    device->first_minor = minor;
    list_add_tail(&device->node, &tmp->node);
    write_unlock(&tape_device_lock);
    return 0;
}

/* remove device from the list */
static void
tape_remove_minor(struct tape_device *device)
{
    write_lock(&tape_device_lock);
    list_del_init(&device->node);
    device->first_minor = -1;
    write_unlock(&tape_device_lock);
}

/*
 * Set a device online.
 *
 * This function is called by the common I/O layer to move a device from the
 * detected but offline into the online state.
 * If we return an error (RC < 0) the device remains in the offline state. This
 * can happen if the device is assigned somewhere else, for example.
 */
int
tape_generic_online(struct tape_device *device,
           struct tape_discipline *discipline)
{
    int rc;

    DBF_LH(6, "tape_enable_device(%p, %p)\n", device, discipline);

    if (device->tape_state != TS_INIT) {
        DBF_LH(3, "Tapestate not INIT (%d)\n", device->tape_state);
        return -EINVAL;
    }

    init_timer(&device->lb_timeout);
    device->lb_timeout.function = tape_long_busy_timeout;

    /* Let the discipline have a go at the device. */
    device->discipline = discipline;
    if (!try_module_get(discipline->owner)) {
        return -EINVAL;
    }

    rc = discipline->setup_device(device);
    if (rc)
        goto out;
    rc = tape_assign_minor(device);
    if (rc)
        goto out_discipline;

    rc = tapechar_setup_device(device);
    if (rc)
        goto out_minor;

    tape_state_set(device, TS_UNUSED);

    DBF_LH(3, "(%08x): Drive set online\n", device->cdev_id);

    return 0;

out_minor:
    tape_remove_minor(device);
out_discipline:
    device->discipline->cleanup_device(device);
    device->discipline = NULL;
out:
    module_put(discipline->owner);
    return rc;
}

static void
tape_cleanup_device(struct tape_device *device)
{
    tapechar_cleanup_device(device);
    device->discipline->cleanup_device(device);
    module_put(device->discipline->owner);
    tape_remove_minor(device);
    tape_med_state_set(device, MS_UNKNOWN);
}

/*
 * Suspend device.
 *
 * Called by the common I/O layer if the drive should be suspended on user
 * request. We refuse to suspend if the device is loaded or in use for the
 * following reason:
 * While the Linux guest is suspended, it might be logged off which causes
 * devices to be detached. Tape devices are automatically rewound and unloaded
 * during DETACH processing (unless the tape device was attached with the
 * NOASSIGN or MULTIUSER option). After rewind/unload, there is no way to
 * resume the original state of the tape device, since we would need to
 * manually re-load the cartridge which was active at suspend time.
 */
int tape_generic_pm_suspend(struct ccw_device *cdev)
{
    struct tape_device *device;

    device = dev_get_drvdata(&cdev->dev);
    if (!device) {
        return -ENODEV;
    }

    DBF_LH(3, "(%08x): tape_generic_pm_suspend(%p)\n",
        device->cdev_id, device);

    if (device->medium_state != MS_UNLOADED) {
        pr_err("A cartridge is loaded in tape device %s, "
               "refusing to suspend\n", dev_name(&cdev->dev));
        return -EBUSY;
    }

    spin_lock_irq(get_ccwdev_lock(device->cdev));
    switch (device->tape_state) {
        case TS_INIT:
        case TS_NOT_OPER:
        case TS_UNUSED:
            spin_unlock_irq(get_ccwdev_lock(device->cdev));
            break;
        default:
            pr_err("Tape device %s is busy, refusing to "
                   "suspend\n", dev_name(&cdev->dev));
            spin_unlock_irq(get_ccwdev_lock(device->cdev));
            return -EBUSY;
    }

    DBF_LH(3, "(%08x): Drive suspended.\n", device->cdev_id);
    return 0;
}

/*
 * Set device offline.
 *
 * Called by the common I/O layer if the drive should set offline on user
 * request. We may prevent this by returning an error.
 * Manual offline is only allowed while the drive is not in use.
 */
int
tape_generic_offline(struct ccw_device *cdev)
{
    struct tape_device *device;

    device = dev_get_drvdata(&cdev->dev);
    if (!device) {
        return -ENODEV;
    }

    DBF_LH(3, "(%08x): tape_generic_offline(%p)\n",
        device->cdev_id, device);

    spin_lock_irq(get_ccwdev_lock(device->cdev));
    switch (device->tape_state) {
        case TS_INIT:
        case TS_NOT_OPER:
            spin_unlock_irq(get_ccwdev_lock(device->cdev));
            break;
        case TS_UNUSED:
            tape_state_set(device, TS_INIT);
            spin_unlock_irq(get_ccwdev_lock(device->cdev));
            tape_cleanup_device(device);
            break;
        default:
            DBF_EVENT(3, "(%08x): Set offline failed "
                "- drive in use.\n",
                device->cdev_id);
            spin_unlock_irq(get_ccwdev_lock(device->cdev));
            return -EBUSY;
    }

    DBF_LH(3, "(%08x): Drive set offline.\n", device->cdev_id);
    return 0;
}

/*
 * Allocate memory for a new device structure.
 */
static struct tape_device *
tape_alloc_device(void)
{
    struct tape_device *device;

    device = kzalloc(sizeof(struct tape_device), GFP_KERNEL);
    if (device == NULL) {
        DBF_EXCEPTION(2, "ti:no mem\n");
        return ERR_PTR(-ENOMEM);
    }
    device->modeset_byte = kmalloc(1, GFP_KERNEL | GFP_DMA);
    if (device->modeset_byte == NULL) {
        DBF_EXCEPTION(2, "ti:no mem\n");
        kfree(device);
        return ERR_PTR(-ENOMEM);
    }
    mutex_init(&device->mutex);
    INIT_LIST_HEAD(&device->req_queue);
    INIT_LIST_HEAD(&device->node);
    init_waitqueue_head(&device->state_change_wq);
    init_waitqueue_head(&device->wait_queue);
    device->tape_state = TS_INIT;
    device->medium_state = MS_UNKNOWN;
    *device->modeset_byte = 0;
    device->first_minor = -1;
    atomic_set(&device->ref_count, 1);
    INIT_DELAYED_WORK(&device->tape_dnr, tape_delayed_next_request);

    return device;
}

/*
 * Get a reference to an existing device structure. This will automatically
 * increment the reference count.
 */
struct tape_device *
tape_get_device(struct tape_device *device)
{
    int count;

    count = atomic_inc_return(&device->ref_count);
    DBF_EVENT(4, "tape_get_device(%p) = %i\n", device, count);
    return device;
}

/*
 * Decrease the reference counter of a devices structure. If the
 * reference counter reaches zero free the device structure.
 * The function returns a NULL pointer to be used by the caller
 * for clearing reference pointers.
 */
void
tape_put_device(struct tape_device *device)
{
    int count;

    count = atomic_dec_return(&device->ref_count);
    DBF_EVENT(4, "tape_put_device(%p) -> %i\n", device, count);
    BUG_ON(count < 0);
    if (count == 0) {
        kfree(device->modeset_byte);
        kfree(device);
    }
}

/*
 * Find tape device by a device index.
 */
struct tape_device *
tape_find_device(int devindex)
{
    struct tape_device *device, *tmp;

    device = ERR_PTR(-ENODEV);
    read_lock(&tape_device_lock);
    list_for_each_entry(tmp, &tape_device_list, node) {
        if (tmp->first_minor / TAPE_MINORS_PER_DEV == devindex) {
            device = tape_get_device(tmp);
            break;
        }
    }
    read_unlock(&tape_device_lock);
    return device;
}

/*
 * Driverfs tape probe function.
 */
int
tape_generic_probe(struct ccw_device *cdev)
{
    struct tape_device *device;
    int ret;
    struct ccw_dev_id dev_id;

    device = tape_alloc_device();
    if (IS_ERR(device))
        return -ENODEV;
    ccw_device_set_options(cdev, CCWDEV_DO_PATHGROUP |
                     CCWDEV_DO_MULTIPATH);
    ret = sysfs_create_group(&cdev->dev.kobj, &tape_attr_group);
    if (ret) {
        tape_put_device(device);
        return ret;
    }
    dev_set_drvdata(&cdev->dev, device);
    cdev->handler = __tape_do_irq;
    device->cdev = cdev;
    ccw_device_get_id(cdev, &dev_id);
    device->cdev_id = devid_to_int(&dev_id);
    return ret;
}

static void
__tape_discard_requests(struct tape_device *device)
{
    struct tape_request *   request;
    struct list_head *  l, *n;

    list_for_each_safe(l, n, &device->req_queue) {
        request = list_entry(l, struct tape_request, list);
        if (request->status == TAPE_REQUEST_IN_IO)
            request->status = TAPE_REQUEST_DONE;
        list_del(&request->list);

        /* Decrease ref_count for removed request. */
        request->device = NULL;
        tape_put_device(device);
        request->rc = -EIO;
        if (request->callback != NULL)
            request->callback(request, request->callback_data);
    }
}

/*
 * Driverfs tape remove function.
 *
 * This function is called whenever the common I/O layer detects the device
 * gone. This can happen at any time and we cannot refuse.
 */
void
tape_generic_remove(struct ccw_device *cdev)
{
    struct tape_device *    device;

    device = dev_get_drvdata(&cdev->dev);
    if (!device) {
        return;
    }
    DBF_LH(3, "(%08x): tape_generic_remove(%p)\n", device->cdev_id, cdev);

    spin_lock_irq(get_ccwdev_lock(device->cdev));
    switch (device->tape_state) {
        case TS_INIT:
            tape_state_set(device, TS_NOT_OPER);
        case TS_NOT_OPER:
            /*
             * Nothing to do.
             */
            spin_unlock_irq(get_ccwdev_lock(device->cdev));
            break;
        case TS_UNUSED:
            /*
             * Need only to release the device.
             */
            tape_state_set(device, TS_NOT_OPER);
            spin_unlock_irq(get_ccwdev_lock(device->cdev));
            tape_cleanup_device(device);
            break;
        default:
            /*
             * There may be requests on the queue. We will not get
             * an interrupt for a request that was running. So we
             * just post them all as I/O errors.
             */
            DBF_EVENT(3, "(%08x): Drive in use vanished!\n",
                device->cdev_id);
            pr_warning("%s: A tape unit was detached while in "
                   "use\n", dev_name(&device->cdev->dev));
            tape_state_set(device, TS_NOT_OPER);
            __tape_discard_requests(device);
            spin_unlock_irq(get_ccwdev_lock(device->cdev));
            tape_cleanup_device(device);
    }

    device = dev_get_drvdata(&cdev->dev);
    if (device) {
        sysfs_remove_group(&cdev->dev.kobj, &tape_attr_group);
        dev_set_drvdata(&cdev->dev, NULL);
        tape_put_device(device);
    }
}

/*
 * Allocate a new tape ccw request
 */
struct tape_request *
tape_alloc_request(int cplength, int datasize)
{
    struct tape_request *request;

    BUG_ON(datasize > PAGE_SIZE || (cplength*sizeof(struct ccw1)) > PAGE_SIZE);

    DBF_LH(6, "tape_alloc_request(%d, %d)\n", cplength, datasize);

    request = kzalloc(sizeof(struct tape_request), GFP_KERNEL);
    if (request == NULL) {
        DBF_EXCEPTION(1, "cqra nomem\n");
        return ERR_PTR(-ENOMEM);
    }
    /* allocate channel program */
    if (cplength > 0) {
        request->cpaddr = kcalloc(cplength, sizeof(struct ccw1),
                      GFP_ATOMIC | GFP_DMA);
        if (request->cpaddr == NULL) {
            DBF_EXCEPTION(1, "cqra nomem\n");
            kfree(request);
            return ERR_PTR(-ENOMEM);
        }
    }
    /* alloc small kernel buffer */
    if (datasize > 0) {
        request->cpdata = kzalloc(datasize, GFP_KERNEL | GFP_DMA);
        if (request->cpdata == NULL) {
            DBF_EXCEPTION(1, "cqra nomem\n");
            kfree(request->cpaddr);
            kfree(request);
            return ERR_PTR(-ENOMEM);
        }
    }
    DBF_LH(6, "New request %p(%p/%p)\n", request, request->cpaddr,
        request->cpdata);

    return request;
}

/*
 * Free tape ccw request
 */
void
tape_free_request (struct tape_request * request)
{
    DBF_LH(6, "Free request %p\n", request);

    if (request->device)
        tape_put_device(request->device);
    kfree(request->cpdata);
    kfree(request->cpaddr);
    kfree(request);
}

static int
__tape_start_io(struct tape_device *device, struct tape_request *request)
{
    int rc;

    rc = ccw_device_start(
        device->cdev,
        request->cpaddr,
        (unsigned long) request,
        0x00,
        request->options
    );
    if (rc == 0) {
        request->status = TAPE_REQUEST_IN_IO;
    } else if (rc == -EBUSY) {
        /* The common I/O subsystem is currently busy. Retry later. */
        request->status = TAPE_REQUEST_QUEUED;
        schedule_delayed_work(&device->tape_dnr, 0);
        rc = 0;
    } else {
        /* Start failed. Remove request and indicate failure. */
        DBF_EVENT(1, "tape: start request failed with RC = %i\n", rc);
    }
    return rc;
}

static void
__tape_start_next_request(struct tape_device *device)
{
    struct list_head *l, *n;
    struct tape_request *request;
    int rc;

    DBF_LH(6, "__tape_start_next_request(%p)\n", device);
    /*
     * Try to start each request on request queue until one is
     * started successful.
     */
    list_for_each_safe(l, n, &device->req_queue) {
        request = list_entry(l, struct tape_request, list);

        /*
         * Avoid race condition if bottom-half was triggered more than
         * once.
         */
        if (request->status == TAPE_REQUEST_IN_IO)
            return;
        /*
         * Request has already been stopped. We have to wait until
         * the request is removed from the queue in the interrupt
         * handling.
         */
        if (request->status == TAPE_REQUEST_DONE)
            return;

        /*
         * We wanted to cancel the request but the common I/O layer
         * was busy at that time. This can only happen if this
         * function is called by delayed_next_request.
         * Otherwise we start the next request on the queue.
         */
        if (request->status == TAPE_REQUEST_CANCEL) {
            rc = __tape_cancel_io(device, request);
        } else {
            rc = __tape_start_io(device, request);
        }
        if (rc == 0)
            return;

        /* Set ending status. */
        request->rc = rc;
        request->status = TAPE_REQUEST_DONE;

        /* Remove from request queue. */
        list_del(&request->list);

        /* Do callback. */
        if (request->callback != NULL)
            request->callback(request, request->callback_data);
    }
}

static void
tape_delayed_next_request(struct work_struct *work)
{
    struct tape_device *device =
        container_of(work, struct tape_device, tape_dnr.work);

    DBF_LH(6, "tape_delayed_next_request(%p)\n", device);
    spin_lock_irq(get_ccwdev_lock(device->cdev));
    __tape_start_next_request(device);
    spin_unlock_irq(get_ccwdev_lock(device->cdev));
}

static void tape_long_busy_timeout(unsigned long data)
{
    struct tape_request *request;
    struct tape_device *device;

    device = (struct tape_device *) data;
    spin_lock_irq(get_ccwdev_lock(device->cdev));
    request = list_entry(device->req_queue.next, struct tape_request, list);
    BUG_ON(request->status != TAPE_REQUEST_LONG_BUSY);
    DBF_LH(6, "%08x: Long busy timeout.\n", device->cdev_id);
    __tape_start_next_request(device);
    device->lb_timeout.data = 0UL;
    tape_put_device(device);
    spin_unlock_irq(get_ccwdev_lock(device->cdev));
}

static void
__tape_end_request(
    struct tape_device *    device,
    struct tape_request *   request,
    int         rc)
{
    DBF_LH(6, "__tape_end_request(%p, %p, %i)\n", device, request, rc);
    if (request) {
        request->rc = rc;
        request->status = TAPE_REQUEST_DONE;

        /* Remove from request queue. */
        list_del(&request->list);

        /* Do callback. */
        if (request->callback != NULL)
            request->callback(request, request->callback_data);
    }

    /* Start next request. */
    if (!list_empty(&device->req_queue))
        __tape_start_next_request(device);
}

/*
 * Write sense data to dbf
 */
void
tape_dump_sense_dbf(struct tape_device *device, struct tape_request *request,
            struct irb *irb)
{
    unsigned int *sptr;
    const char* op;

    if (request != NULL)
        op = tape_op_verbose[request->op];
    else
        op = "---";
    DBF_EVENT(3, "DSTAT : %02x   CSTAT: %02x\n",
          irb->scsw.cmd.dstat, irb->scsw.cmd.cstat);
    DBF_EVENT(3, "DEVICE: %08x OP\t: %s\n", device->cdev_id, op);
    sptr = (unsigned int *) irb->ecw;
    DBF_EVENT(3, "%08x %08x\n", sptr[0], sptr[1]);
    DBF_EVENT(3, "%08x %08x\n", sptr[2], sptr[3]);
    DBF_EVENT(3, "%08x %08x\n", sptr[4], sptr[5]);
    DBF_EVENT(3, "%08x %08x\n", sptr[6], sptr[7]);
}

/*
 * I/O helper function. Adds the request to the request queue
 * and starts it if the tape is idle. Has to be called with
 * the device lock held.
 */
static int
__tape_start_request(struct tape_device *device, struct tape_request *request)
{
    int rc;

    switch (request->op) {
        case TO_MSEN:
        case TO_ASSIGN:
        case TO_UNASSIGN:
        case TO_READ_ATTMSG:
        case TO_RDC:
            if (device->tape_state == TS_INIT)
                break;
            if (device->tape_state == TS_UNUSED)
                break;
        default:
            if (device->tape_state == TS_BLKUSE)
                break;
            if (device->tape_state != TS_IN_USE)
                return -ENODEV;
    }

    /* Increase use count of device for the added request. */
    request->device = tape_get_device(device);

    if (list_empty(&device->req_queue)) {
        /* No other requests are on the queue. Start this one. */
        rc = __tape_start_io(device, request);
        if (rc)
            return rc;

        DBF_LH(5, "Request %p added for execution.\n", request);
        list_add(&request->list, &device->req_queue);
    } else {
        DBF_LH(5, "Request %p add to queue.\n", request);
        request->status = TAPE_REQUEST_QUEUED;
        list_add_tail(&request->list, &device->req_queue);
    }
    return 0;
}

/*
 * Add the request to the request queue, try to start it if the
 * tape is idle. Return without waiting for end of i/o.
 */
int
tape_do_io_async(struct tape_device *device, struct tape_request *request)
{
    int rc;

    DBF_LH(6, "tape_do_io_async(%p, %p)\n", device, request);

    spin_lock_irq(get_ccwdev_lock(device->cdev));
    /* Add request to request queue and try to start it. */
    rc = __tape_start_request(device, request);
    spin_unlock_irq(get_ccwdev_lock(device->cdev));
    return rc;
}

/*
 * tape_do_io/__tape_wake_up
 * Add the request to the request queue, try to start it if the
 * tape is idle and wait uninterruptible for its completion.
 */
static void
__tape_wake_up(struct tape_request *request, void *data)
{
    request->callback = NULL;
    wake_up((wait_queue_head_t *) data);
}

int
tape_do_io(struct tape_device *device, struct tape_request *request)
{
    int rc;

    spin_lock_irq(get_ccwdev_lock(device->cdev));
    /* Setup callback */
    request->callback = __tape_wake_up;
    request->callback_data = &device->wait_queue;
    /* Add request to request queue and try to start it. */
    rc = __tape_start_request(device, request);
    spin_unlock_irq(get_ccwdev_lock(device->cdev));
    if (rc)
        return rc;
    /* Request added to the queue. Wait for its completion. */
    wait_event(device->wait_queue, (request->callback == NULL));
    /* Get rc from request */
    return request->rc;
}

/*
 * tape_do_io_interruptible/__tape_wake_up_interruptible
 * Add the request to the request queue, try to start it if the
 * tape is idle and wait uninterruptible for its completion.
 */
static void
__tape_wake_up_interruptible(struct tape_request *request, void *data)
{
    request->callback = NULL;
    wake_up_interruptible((wait_queue_head_t *) data);
}

int
tape_do_io_interruptible(struct tape_device *device,
             struct tape_request *request)
{
    int rc;

    spin_lock_irq(get_ccwdev_lock(device->cdev));
    /* Setup callback */
    request->callback = __tape_wake_up_interruptible;
    request->callback_data = &device->wait_queue;
    rc = __tape_start_request(device, request);
    spin_unlock_irq(get_ccwdev_lock(device->cdev));
    if (rc)
        return rc;
    /* Request added to the queue. Wait for its completion. */
    rc = wait_event_interruptible(device->wait_queue,
                      (request->callback == NULL));
    if (rc != -ERESTARTSYS)
        /* Request finished normally. */
        return request->rc;

    /* Interrupted by a signal. We have to stop the current request. */
    spin_lock_irq(get_ccwdev_lock(device->cdev));
    rc = __tape_cancel_io(device, request);
    spin_unlock_irq(get_ccwdev_lock(device->cdev));
    if (rc == 0) {
        /* Wait for the interrupt that acknowledges the halt. */
        do {
            rc = wait_event_interruptible(
                device->wait_queue,
                (request->callback == NULL)
            );
        } while (rc == -ERESTARTSYS);

        DBF_EVENT(3, "IO stopped on %08x\n", device->cdev_id);
        rc = -ERESTARTSYS;
    }
    return rc;
}

/*
 * Stop running ccw.
 */
int
tape_cancel_io(struct tape_device *device, struct tape_request *request)
{
    int rc;

    spin_lock_irq(get_ccwdev_lock(device->cdev));
    rc = __tape_cancel_io(device, request);
    spin_unlock_irq(get_ccwdev_lock(device->cdev));
    return rc;
}

/*
 * Tape interrupt routine, called from the ccw_device layer
 */
static void
__tape_do_irq (struct ccw_device *cdev, unsigned long intparm, struct irb *irb)
{
    struct tape_device *device;
    struct tape_request *request;
    int rc;

    device = dev_get_drvdata(&cdev->dev);
    if (device == NULL) {
        return;
    }
    request = (struct tape_request *) intparm;

    DBF_LH(6, "__tape_do_irq(device=%p, request=%p)\n", device, request);

    /* On special conditions irb is an error pointer */
    if (IS_ERR(irb)) {
        /* FIXME: What to do with the request? */
        switch (PTR_ERR(irb)) {
            case -ETIMEDOUT:
                DBF_LH(1, "(%08x): Request timed out\n",
                       device->cdev_id);
            case -EIO:
                __tape_end_request(device, request, -EIO);
                break;
            default:
                DBF_LH(1, "(%08x): Unexpected i/o error %li\n",
                       device->cdev_id, PTR_ERR(irb));
        }
        return;
    }

    /*
     * If the condition code is not zero and the start function bit is
     * still set, this is an deferred error and the last start I/O did
     * not succeed. At this point the condition that caused the deferred
     * error might still apply. So we just schedule the request to be
     * started later.
     */
    if (irb->scsw.cmd.cc != 0 &&
        (irb->scsw.cmd.fctl & SCSW_FCTL_START_FUNC) &&
        (request->status == TAPE_REQUEST_IN_IO)) {
        DBF_EVENT(3,"(%08x): deferred cc=%i, fctl=%i. restarting\n",
            device->cdev_id, irb->scsw.cmd.cc, irb->scsw.cmd.fctl);
        request->status = TAPE_REQUEST_QUEUED;
        schedule_delayed_work(&device->tape_dnr, HZ);
        return;
    }

    /* May be an unsolicited irq */
    if(request != NULL)
        request->rescnt = irb->scsw.cmd.count;
    else if ((irb->scsw.cmd.dstat == 0x85 || irb->scsw.cmd.dstat == 0x80) &&
         !list_empty(&device->req_queue)) {
        /* Not Ready to Ready after long busy ? */
        struct tape_request *req;
        req = list_entry(device->req_queue.next,
                 struct tape_request, list);
        if (req->status == TAPE_REQUEST_LONG_BUSY) {
            DBF_EVENT(3, "(%08x): del timer\n", device->cdev_id);
            if (del_timer(&device->lb_timeout)) {
                device->lb_timeout.data = 0UL;
                tape_put_device(device);
                __tape_start_next_request(device);
            }
            return;
        }
    }
    if (irb->scsw.cmd.dstat != 0x0c) {
        /* Set the 'ONLINE' flag depending on sense byte 1 */
        if(*(((__u8 *) irb->ecw) + 1) & SENSE_DRIVE_ONLINE)
            device->tape_generic_status |= GMT_ONLINE(~0);
        else
            device->tape_generic_status &= ~GMT_ONLINE(~0);

        /*
         * Any request that does not come back with channel end
         * and device end is unusual. Log the sense data.
         */
        DBF_EVENT(3,"-- Tape Interrupthandler --\n");
        tape_dump_sense_dbf(device, request, irb);
    } else {
        /* Upon normal completion the device _is_ online */
        device->tape_generic_status |= GMT_ONLINE(~0);
    }
    if (device->tape_state == TS_NOT_OPER) {
        DBF_EVENT(6, "tape:device is not operational\n");
        return;
    }

    /*
     * Request that were canceled still come back with an interrupt.
     * To detect these request the state will be set to TAPE_REQUEST_DONE.
     */
    if(request != NULL && request->status == TAPE_REQUEST_DONE) {
        __tape_end_request(device, request, -EIO);
        return;
    }

    rc = device->discipline->irq(device, request, irb);
    /*
     * rc < 0 : request finished unsuccessfully.
     * rc == TAPE_IO_SUCCESS: request finished successfully.
     * rc == TAPE_IO_PENDING: request is still running. Ignore rc.
     * rc == TAPE_IO_RETRY: request finished but needs another go.
     * rc == TAPE_IO_STOP: request needs to get terminated.
     */
    switch (rc) {
        case TAPE_IO_SUCCESS:
            /* Upon normal completion the device _is_ online */
            device->tape_generic_status |= GMT_ONLINE(~0);
            __tape_end_request(device, request, rc);
            break;
        case TAPE_IO_PENDING:
            break;
        case TAPE_IO_LONG_BUSY:
            device->lb_timeout.data =
                (unsigned long) tape_get_device(device);
            device->lb_timeout.expires = jiffies +
                LONG_BUSY_TIMEOUT * HZ;
            DBF_EVENT(3, "(%08x): add timer\n", device->cdev_id);
            add_timer(&device->lb_timeout);
            request->status = TAPE_REQUEST_LONG_BUSY;
            break;
        case TAPE_IO_RETRY:
            rc = __tape_start_io(device, request);
            if (rc)
                __tape_end_request(device, request, rc);
            break;
        case TAPE_IO_STOP:
            rc = __tape_cancel_io(device, request);
            if (rc)
                __tape_end_request(device, request, rc);
            break;
        default:
            if (rc > 0) {
                DBF_EVENT(6, "xunknownrc\n");
                __tape_end_request(device, request, -EIO);
            } else {
                __tape_end_request(device, request, rc);
            }
            break;
    }
}

/*
 * Tape device open function used by tape_char frontend.
 */
int
tape_open(struct tape_device *device)
{
    int rc;

    spin_lock_irq(get_ccwdev_lock(device->cdev));
    if (device->tape_state == TS_NOT_OPER) {
        DBF_EVENT(6, "TAPE:nodev\n");
        rc = -ENODEV;
    } else if (device->tape_state == TS_IN_USE) {
        DBF_EVENT(6, "TAPE:dbusy\n");
        rc = -EBUSY;
    } else if (device->tape_state == TS_BLKUSE) {
        DBF_EVENT(6, "TAPE:dbusy\n");
        rc = -EBUSY;
    } else if (device->discipline != NULL &&
           !try_module_get(device->discipline->owner)) {
        DBF_EVENT(6, "TAPE:nodisc\n");
        rc = -ENODEV;
    } else {
        tape_state_set(device, TS_IN_USE);
        rc = 0;
    }
    spin_unlock_irq(get_ccwdev_lock(device->cdev));
    return rc;
}

/*
 * Tape device release function used by tape_char frontend.
 */
int
tape_release(struct tape_device *device)
{
    spin_lock_irq(get_ccwdev_lock(device->cdev));
    if (device->tape_state == TS_IN_USE)
        tape_state_set(device, TS_UNUSED);
    module_put(device->discipline->owner);
    spin_unlock_irq(get_ccwdev_lock(device->cdev));
    return 0;
}

/*
 * Execute a magnetic tape command a number of times.
 */
int
tape_mtop(struct tape_device *device, int mt_op, int mt_count)
{
    tape_mtop_fn fn;
    int rc;

    DBF_EVENT(6, "TAPE:mtio\n");
    DBF_EVENT(6, "TAPE:ioop: %x\n", mt_op);
    DBF_EVENT(6, "TAPE:arg:  %x\n", mt_count);

    if (mt_op < 0 || mt_op >= TAPE_NR_MTOPS)
        return -EINVAL;
    fn = device->discipline->mtop_array[mt_op];
    if (fn == NULL)
        return -EINVAL;

    /* We assume that the backends can handle count up to 500. */
    if (mt_op == MTBSR  || mt_op == MTFSR  || mt_op == MTFSF  ||
        mt_op == MTBSF  || mt_op == MTFSFM || mt_op == MTBSFM) {
        rc = 0;
        for (; mt_count > 500; mt_count -= 500)
            if ((rc = fn(device, 500)) != 0)
                break;
        if (rc == 0)
            rc = fn(device, mt_count);
    } else
        rc = fn(device, mt_count);
    return rc;

}

/*
 * Tape init function.
 */
static int
tape_init (void)
{
    TAPE_DBF_AREA = debug_register ( "tape", 2, 2, 4*sizeof(long));
    debug_register_view(TAPE_DBF_AREA, &debug_sprintf_view);
#ifdef DBF_LIKE_HELL
    debug_set_level(TAPE_DBF_AREA, 6);
#endif
    DBF_EVENT(3, "tape init\n");
    tape_proc_init();
    tapechar_init ();
    return 0;
}

/*
 * Tape exit function.
 */
static void
tape_exit(void)
{
    DBF_EVENT(6, "tape exit\n");

    /* Get rid of the frontends */
    tapechar_exit();
    tape_proc_cleanup();
    debug_unregister (TAPE_DBF_AREA);
}

MODULE_AUTHOR("(C) 2001 IBM Deutschland Entwicklung GmbH by Carsten Otte and "
          "Michael Holzheu ([email protected],[email protected])");
MODULE_DESCRIPTION("Linux on zSeries channel attached tape device driver");
MODULE_LICENSE("GPL");

module_init(tape_init);
module_exit(tape_exit);

EXPORT_SYMBOL(tape_generic_remove);
EXPORT_SYMBOL(tape_generic_probe);
EXPORT_SYMBOL(tape_generic_online);
EXPORT_SYMBOL(tape_generic_offline);
EXPORT_SYMBOL(tape_generic_pm_suspend);
EXPORT_SYMBOL(tape_put_device);
EXPORT_SYMBOL(tape_get_device);
EXPORT_SYMBOL(tape_state_verbose);
EXPORT_SYMBOL(tape_op_verbose);
EXPORT_SYMBOL(tape_state_set);
EXPORT_SYMBOL(tape_med_state_set);
EXPORT_SYMBOL(tape_alloc_request);
EXPORT_SYMBOL(tape_free_request);
EXPORT_SYMBOL(tape_dump_sense_dbf);
EXPORT_SYMBOL(tape_do_io);
EXPORT_SYMBOL(tape_do_io_async);
EXPORT_SYMBOL(tape_do_io_interruptible);
EXPORT_SYMBOL(tape_cancel_io);
EXPORT_SYMBOL(tape_mtop);