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tape_core.c

/*
 *  drivers/s390/char/tape_core.c
 *    basic function of the tape device driver
 *
 *  S390 and zSeries version
 *    Copyright IBM Corp. 2001,2006
 *    Author(s): Carsten Otte <cotte@de.ibm.com>
 *           Michael Holzheu <holzheu@de.ibm.com>
 *           Tuan Ngo-Anh <ngoanh@de.ibm.com>
 *           Martin Schwidefsky <schwidefsky@de.ibm.com>
 *           Stefan Bader <shbader@de.ibm.com>
 */

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

#define TAPE_DBF_AREA   tape_core_dbf

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

#define PRINTK_HEADER "TAPE_CORE: "
#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 struct list_head tape_device_list = LIST_HEAD_INIT(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
busid_to_int(char *bus_id)
{
      int   dec;
      int   d;
      char *      s;

      for(s = bus_id, d = 0; *s != '\0' && *s != '.'; s++)
            d = (d * 10) + (*s - '0');
      dec = d;
      for(s++, d = 0; *s != '\0' && *s != '.'; s++)
            d = (d * 10) + (*s - '0');
      dec = (dec << 8) + d;

      for(s++; *s != '\0'; s++) {
            if (*s >= '0' && *s <= '9') {
                  d = *s - '0';
            } else if (*s >= 'a' && *s <= 'f') {
                  d = *s - 'a' + 10;
            } else {
                  d = *s - 'A' + 10;
            }
            dec = (dec << 4) + d;
      }

      return dec;
}

/*
 * 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 = (struct tape_device *) dev->driver_data;
      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 = (struct tape_device *) dev->driver_data;
      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 = (struct tape_device *) dev->driver_data;
      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 = (struct tape_device *) dev->driver_data;
      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 = (struct tape_device *) dev->driver_data;

      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);
}

void
tape_med_state_set(struct tape_device *device, enum tape_medium_state newstate)
{
      if (device->medium_state == newstate)
            return;
      switch(newstate){
      case MS_UNLOADED:
            device->tape_generic_status |= GMT_DR_OPEN(~0);
            PRINT_INFO("(%s): Tape is unloaded\n",
                     device->cdev->dev.bus_id);
            break;
      case MS_LOADED:
            device->tape_generic_status &= ~GMT_DR_OPEN(~0);
            PRINT_INFO("(%s): Tape has been mounted\n",
                     device->cdev->dev.bus_id);
            break;
      default:
            // print nothing
            break;
      }
      device->medium_state = newstate;
      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)) {
            PRINT_ERR("Cannot get module. Module gone.\n");
            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;
      rc = tapeblock_setup_device(device);
      if (rc)
            goto out_char;

      tape_state_set(device, TS_UNUSED);

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

      return 0;

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

static void
tape_cleanup_device(struct tape_device *device)
{
      tapeblock_cleanup_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);
}

/*
 * 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 tape_device *device)
{
      if (!device) {
            PRINT_ERR("tape_generic_offline: no such device\n");
            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);
                  PRINT_WARN("(%s): Set offline failed "
                        "- drive in use.\n",
                        device->cdev->dev.bus_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");
            PRINT_INFO ("can't allocate memory for "
                      "tape info structure\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");
            PRINT_INFO("can't allocate memory for modeset byte\n");
            kfree(device);
            return ERR_PTR(-ENOMEM);
      }
      INIT_LIST_HEAD(&device->req_queue);
      INIT_LIST_HEAD(&device->node);
      init_waitqueue_head(&device->state_change_wq);
      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_reference(struct tape_device *device)
{
      DBF_EVENT(4, "tape_get_device_reference(%p) = %i\n", device,
            atomic_inc_return(&device->ref_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.
 */
struct tape_device *
tape_put_device(struct tape_device *device)
{
      int remain;

      remain = atomic_dec_return(&device->ref_count);
      if (remain > 0) {
            DBF_EVENT(4, "tape_put_device(%p) -> %i\n", device, remain);
      } else {
            if (remain < 0) {
                  DBF_EVENT(4, "put device without reference\n");
                  PRINT_ERR("put device without reference\n");
            } else {
                  DBF_EVENT(4, "tape_free_device(%p)\n", device);
                  kfree(device->modeset_byte);
                  kfree(device);
            }
      }

      return NULL;                  
}

/*
 * Find tape device by a device index.
 */
struct tape_device *
tape_get_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_reference(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;

      device = tape_alloc_device();
      if (IS_ERR(device))
            return -ENODEV;
      ccw_device_set_options(cdev, CCWDEV_DO_PATHGROUP);
      ret = sysfs_create_group(&cdev->dev.kobj, &tape_attr_group);
      if (ret) {
            tape_put_device(device);
            PRINT_ERR("probe failed for tape device %s\n", cdev->dev.bus_id);
            return ret;
      }
      cdev->dev.driver_data = device;
      cdev->handler = __tape_do_irq;
      device->cdev = cdev;
      device->cdev_id = busid_to_int(cdev->dev.bus_id);
      PRINT_INFO("tape device %s found\n", cdev->dev.bus_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 = 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 = cdev->dev.driver_data;
      if (!device) {
            PRINT_ERR("No device pointer in tape_generic_remove!\n");
            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);
                  PRINT_WARN("(%s): Drive in use vanished - "
                        "expect trouble!\n",
                        device->cdev->dev.bus_id);
                  PRINT_WARN("State was %i\n", device->tape_state);
                  tape_state_set(device, TS_NOT_OPER);
                  __tape_discard_requests(device);
                  spin_unlock_irq(get_ccwdev_lock(device->cdev));
                  tape_cleanup_device(device);
      }

      if (cdev->dev.driver_data != NULL) {
            sysfs_remove_group(&cdev->dev.kobj, &tape_attr_group);
            cdev->dev.driver_data = tape_put_device(cdev->dev.driver_data);
      }
}

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

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

      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 != NULL) {
            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;

#ifdef CONFIG_S390_TAPE_BLOCK
      if (request->op == TO_BLOCK)
            device->discipline->check_locate(device, request);
#endif
      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);
      if (request->status != TAPE_REQUEST_LONG_BUSY)
            BUG();
      DBF_LH(6, "%08x: Long busy timeout.\n", device->cdev_id);
      __tape_start_next_request(device);
      device->lb_timeout.data = (unsigned long) 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 console/dbf
 */
void
tape_dump_sense(struct tape_device* device, struct tape_request *request,
            struct irb *irb)
{
      unsigned int *sptr;

      PRINT_INFO("-------------------------------------------------\n");
      PRINT_INFO("DSTAT : %02x  CSTAT: %02x     CPA: %04x\n",
               irb->scsw.dstat, irb->scsw.cstat, irb->scsw.cpa);
      PRINT_INFO("DEVICE: %s\n", device->cdev->dev.bus_id);
      if (request != NULL)
            PRINT_INFO("OP      : %s\n", tape_op_verbose[request->op]);

      sptr = (unsigned int *) irb->ecw;
      PRINT_INFO("Sense data: %08X %08X %08X %08X \n",
               sptr[0], sptr[1], sptr[2], sptr[3]);
      PRINT_INFO("Sense data: %08X %08X %08X %08X \n",
               sptr[4], sptr[5], sptr[6], sptr[7]);
      PRINT_INFO("--------------------------------------------------\n");
}

/*
 * 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.dstat,irb->scsw.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_reference(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)
{
      wait_queue_head_t wq;
      int rc;

      init_waitqueue_head(&wq);
      spin_lock_irq(get_ccwdev_lock(device->cdev));
      /* Setup callback */
      request->callback = __tape_wake_up;
      request->callback_data = &wq;
      /* 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(wq, (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)
{
      wait_queue_head_t wq;
      int rc;

      init_waitqueue_head(&wq);
      spin_lock_irq(get_ccwdev_lock(device->cdev));
      /* Setup callback */
      request->callback = __tape_wake_up_interruptible;
      request->callback_data = &wq;
      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(wq, (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(
                        wq,
                        (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 = (struct tape_device *) cdev->dev.driver_data;
      if (device == NULL) {
            PRINT_ERR("could not get device structure for %s "
                    "in interrupt\n", cdev->dev.bus_id);
            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:
                        PRINT_WARN("(%s): Request timed out\n",
                              cdev->dev.bus_id);
                  case -EIO:
                        __tape_end_request(device, request, -EIO);
                        break;
                  default:
                        PRINT_ERR("(%s): Unexpected i/o error %li\n",
                              cdev->dev.bus_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.cc != 0 && (irb->scsw.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.cc, irb->scsw.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.count;
      else if ((irb->scsw.dstat == 0x85 || irb->scsw.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 = (unsigned long)
                              tape_put_device(device);
                        __tape_start_next_request(device);
                  }
                  return;
            }
      }
      if (irb->scsw.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_reference(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");
                        PRINT_ERR("Invalid return code from discipline "
                              "interrupt function.\n");
                        __tape_end_request(device, request, -EIO);
                  } else {
                        __tape_end_request(device, request, rc);
                  }
                  break;
      }
}

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

      spin_lock(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(get_ccwdev_lock(device->cdev));
      return rc;
}

/*
 * Tape device release function used by tape_char & tape_block frontends.
 */
int
tape_release(struct tape_device *device)
{
      spin_lock(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(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 ();
      tapeblock_init ();
      return 0;
}

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

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

MODULE_AUTHOR("(C) 2001 IBM Deutschland Entwicklung GmbH by Carsten Otte and "
            "Michael Holzheu (cotte@de.ibm.com,holzheu@de.ibm.com)");
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_put_device);
EXPORT_SYMBOL(tape_get_device_reference);
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);
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);

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