/*
 *    tape device discipline for 3480/3490 tapes.
 *
 *    Copyright IBM Corp. 2001, 2009
 *    Author(s): Carsten Otte <cotte@de.ibm.com>
 *               Tuan Ngo-Anh <ngoanh@de.ibm.com>
 *               Martin Schwidefsky <schwidefsky@de.ibm.com>
 */

#define KMSG_COMPONENT "tape_34xx"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/module.h>
#include <linux/init.h>
#include <linux/bio.h>
#include <linux/workqueue.h>
#include <linux/slab.h>

#define TAPE_DBF_AREA   tape_34xx_dbf

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

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

#define TAPE34XX_FMT_3480       0
#define TAPE34XX_FMT_3480_2_XF  1
#define TAPE34XX_FMT_3480_XF    2

struct tape_34xx_block_id {
        unsigned int    wrap            : 1;
        unsigned int    segment         : 7;
        unsigned int    format          : 2;
        unsigned int    block           : 22;
};

/*
 * A list of block ID's is used to faster seek blocks.
 */
struct tape_34xx_sbid {
        struct list_head                list;
        struct tape_34xx_block_id       bid;
};

static void tape_34xx_delete_sbid_from(struct tape_device *, int);

/*
 * Medium sense for 34xx tapes. There is no 'real' medium sense call.
 * So we just do a normal sense.
 */
static void __tape_34xx_medium_sense(struct tape_request *request)
{
        struct tape_device *device = request->device;
        unsigned char *sense;

        if (request->rc == 0) {
                sense = request->cpdata;

                /*
                 * This isn't quite correct. But since INTERVENTION_REQUIRED
                 * means that the drive is 'neither ready nor on-line' it is
                 * only slightly inaccurate to say there is no tape loaded if
                 * the drive isn't online...
                 */
                if (sense[0] & SENSE_INTERVENTION_REQUIRED)
                        tape_med_state_set(device, MS_UNLOADED);
                else
                        tape_med_state_set(device, MS_LOADED);

                if (sense[1] & SENSE_WRITE_PROTECT)
                        device->tape_generic_status |= GMT_WR_PROT(~0);
                else
                        device->tape_generic_status &= ~GMT_WR_PROT(~0);
        } else
                DBF_EVENT(4, "tape_34xx: medium sense failed with rc=%d\n",
                        request->rc);
        tape_free_request(request);
}

static int tape_34xx_medium_sense(struct tape_device *device)
{
        struct tape_request *request;
        int rc;

        request = tape_alloc_request(1, 32);
        if (IS_ERR(request)) {
                DBF_EXCEPTION(6, "MSEN fail\n");
                return PTR_ERR(request);
        }

        request->op = TO_MSEN;
        tape_ccw_end(request->cpaddr, SENSE, 32, request->cpdata);
        rc = tape_do_io_interruptible(device, request);
        __tape_34xx_medium_sense(request);
        return rc;
}

static void tape_34xx_medium_sense_async(struct tape_device *device)
{
        struct tape_request *request;

        request = tape_alloc_request(1, 32);
        if (IS_ERR(request)) {
                DBF_EXCEPTION(6, "MSEN fail\n");
                return;
        }

        request->op = TO_MSEN;
        tape_ccw_end(request->cpaddr, SENSE, 32, request->cpdata);
        request->callback = (void *) __tape_34xx_medium_sense;
        request->callback_data = NULL;
        tape_do_io_async(device, request);
}

struct tape_34xx_work {
        struct tape_device      *device;
        enum tape_op             op;
        struct work_struct       work;
};

/*
 * These functions are currently used only to schedule a medium_sense for
 * later execution. This is because we get an interrupt whenever a medium
 * is inserted but cannot call tape_do_io* from an interrupt context.
 * Maybe that's useful for other actions we want to start from the
 * interrupt handler.
 * Note: the work handler is called by the system work queue. The tape
 * commands started by the handler need to be asynchrounous, otherwise
 * a deadlock can occur e.g. in case of a deferred cc=1 (see __tape_do_irq).
 */
static void
tape_34xx_work_handler(struct work_struct *work)
{
        struct tape_34xx_work *p =
                container_of(work, struct tape_34xx_work, work);
        struct tape_device *device = p->device;

        switch(p->op) {
                case TO_MSEN:
                        tape_34xx_medium_sense_async(device);
                        break;
                default:
                        DBF_EVENT(3, "T34XX: internal error: unknown work\n");
        }
        tape_put_device(device);
        kfree(p);
}

static int
tape_34xx_schedule_work(struct tape_device *device, enum tape_op op)
{
        struct tape_34xx_work *p;

        if ((p = kzalloc(sizeof(*p), GFP_ATOMIC)) == NULL)
                return -ENOMEM;

        INIT_WORK(&p->work, tape_34xx_work_handler);

        p->device = tape_get_device(device);
        p->op     = op;

        schedule_work(&p->work);
        return 0;
}

/*
 * Done Handler is called when dev stat = DEVICE-END (successful operation)
 */
static inline int
tape_34xx_done(struct tape_request *request)
{
        DBF_EVENT(6, "%s done\n", tape_op_verbose[request->op]);

        switch (request->op) {
                case TO_DSE:
                case TO_RUN:
                case TO_WRI:
                case TO_WTM:
                case TO_ASSIGN:
                case TO_UNASSIGN:
                        tape_34xx_delete_sbid_from(request->device, 0);
                        break;
                default:
                        ;
        }
        return TAPE_IO_SUCCESS;
}

static inline int
tape_34xx_erp_failed(struct tape_request *request, int rc)
{
        DBF_EVENT(3, "Error recovery failed for %s (RC=%d)\n",
                  tape_op_verbose[request->op], rc);
        return rc;
}

static inline int
tape_34xx_erp_succeeded(struct tape_request *request)
{
        DBF_EVENT(3, "Error Recovery successful for %s\n",
                  tape_op_verbose[request->op]);
        return tape_34xx_done(request);
}

static inline int
tape_34xx_erp_retry(struct tape_request *request)
{
        DBF_EVENT(3, "xerp retr %s\n", tape_op_verbose[request->op]);
        return TAPE_IO_RETRY;
}

/*
 * This function is called, when no request is outstanding and we get an
 * interrupt
 */
static int
tape_34xx_unsolicited_irq(struct tape_device *device, struct irb *irb)
{
        if (irb->scsw.cmd.dstat == 0x85) { /* READY */
                /* A medium was inserted in the drive. */
                DBF_EVENT(6, "xuud med\n");
                tape_34xx_delete_sbid_from(device, 0);
                tape_34xx_schedule_work(device, TO_MSEN);
        } else {
                DBF_EVENT(3, "unsol.irq! dev end: %08x\n", device->cdev_id);
                tape_dump_sense_dbf(device, NULL, irb);
        }
        return TAPE_IO_SUCCESS;
}

/*
 * Read Opposite Error Recovery Function:
 * Used, when Read Forward does not work
 */
static int
tape_34xx_erp_read_opposite(struct tape_device *device,
                            struct tape_request *request)
{
        if (request->op == TO_RFO) {
                /*
                 * We did read forward, but the data could not be read
                 * *correctly*. We transform the request to a read backward
                 * and try again.
                 */
                tape_std_read_backward(device, request);
                return tape_34xx_erp_retry(request);
        }

        /*
         * We tried to read forward and backward, but hat no
         * success -> failed.
         */
        return tape_34xx_erp_failed(request, -EIO);
}

static int
tape_34xx_erp_bug(struct tape_device *device, struct tape_request *request,
                  struct irb *irb, int no)
{
        if (request->op != TO_ASSIGN) {
                dev_err(&device->cdev->dev, "An unexpected condition %d "
                        "occurred in tape error recovery\n", no);
                tape_dump_sense_dbf(device, request, irb);
        }
        return tape_34xx_erp_failed(request, -EIO);
}

/*
 * Handle data overrun between cu and drive. The channel speed might
 * be too slow.
 */
static int
tape_34xx_erp_overrun(struct tape_device *device, struct tape_request *request,
                      struct irb *irb)
{
        if (irb->ecw[3] == 0x40) {
                dev_warn (&device->cdev->dev, "A data overrun occurred between"
                        " the control unit and tape unit\n");
                return tape_34xx_erp_failed(request, -EIO);
        }
        return tape_34xx_erp_bug(device, request, irb, -1);
}

/*
 * Handle record sequence error.
 */
static int
tape_34xx_erp_sequence(struct tape_device *device,
                       struct tape_request *request, struct irb *irb)
{
        if (irb->ecw[3] == 0x41) {
                /*
                 * cu detected incorrect block-id sequence on tape.
                 */
                dev_warn (&device->cdev->dev, "The block ID sequence on the "
                        "tape is incorrect\n");
                return tape_34xx_erp_failed(request, -EIO);
        }
        /*
         * Record sequence error bit is set, but erpa does not
         * show record sequence error.
         */
        return tape_34xx_erp_bug(device, request, irb, -2);
}

/*
 * This function analyses the tape's sense-data in case of a unit-check.
 * If possible, it tries to recover from the error. Else the user is
 * informed about the problem.
 */
static int
tape_34xx_unit_check(struct tape_device *device, struct tape_request *request,
                     struct irb *irb)
{
        int inhibit_cu_recovery;
        __u8* sense;

        inhibit_cu_recovery = (*device->modeset_byte & 0x80) ? 1 : 0;
        sense = irb->ecw;

        if (
                sense[0] & SENSE_COMMAND_REJECT &&
                sense[1] & SENSE_WRITE_PROTECT
        ) {
                if (
                        request->op == TO_DSE ||
                        request->op == TO_WRI ||
                        request->op == TO_WTM
                ) {
                        /* medium is write protected */
                        return tape_34xx_erp_failed(request, -EACCES);
                } else {
                        return tape_34xx_erp_bug(device, request, irb, -3);
                }
        }

        /*
         * Special cases for various tape-states when reaching
         * end of recorded area
         *
         * FIXME: Maybe a special case of the special case:
         *        sense[0] == SENSE_EQUIPMENT_CHECK &&
         *        sense[1] == SENSE_DRIVE_ONLINE    &&
         *        sense[3] == 0x47 (Volume Fenced)
         *
         *        This was caused by continued FSF or FSR after an
         *        'End Of Data'.
         */
        if ((
                sense[0] == SENSE_DATA_CHECK      ||
                sense[0] == SENSE_EQUIPMENT_CHECK ||
                sense[0] == SENSE_EQUIPMENT_CHECK + SENSE_DEFERRED_UNIT_CHECK
        ) && (
                sense[1] == SENSE_DRIVE_ONLINE ||
                sense[1] == SENSE_BEGINNING_OF_TAPE + SENSE_WRITE_MODE
        )) {
                switch (request->op) {
                /*
                 * sense[0] == SENSE_DATA_CHECK   &&
                 * sense[1] == SENSE_DRIVE_ONLINE
                 * sense[3] == 0x36 (End Of Data)
                 *
                 * Further seeks might return a 'Volume Fenced'.
                 */
                case TO_FSF:
                case TO_FSB:
                        /* Trying to seek beyond end of recorded area */
                        return tape_34xx_erp_failed(request, -ENOSPC);
                case TO_BSB:
                        return tape_34xx_erp_retry(request);

                /*
                 * sense[0] == SENSE_DATA_CHECK   &&
                 * sense[1] == SENSE_DRIVE_ONLINE &&
                 * sense[3] == 0x36 (End Of Data)
                 */
                case TO_LBL:
                        /* Block could not be located. */
                        tape_34xx_delete_sbid_from(device, 0);
                        return tape_34xx_erp_failed(request, -EIO);

                case TO_RFO:
                        /* Read beyond end of recorded area -> 0 bytes read */
                        return tape_34xx_erp_failed(request, 0);

                /*
                 * sense[0] == SENSE_EQUIPMENT_CHECK &&
                 * sense[1] == SENSE_DRIVE_ONLINE    &&
                 * sense[3] == 0x38 (Physical End Of Volume)
                 */
                case TO_WRI:
                        /* Writing at physical end of volume */
                        return tape_34xx_erp_failed(request, -ENOSPC);
                default:
                        return tape_34xx_erp_failed(request, 0);
                }
        }

        /* Sensing special bits */
        if (sense[0] & SENSE_BUS_OUT_CHECK)
                return tape_34xx_erp_retry(request);

        if (sense[0] & SENSE_DATA_CHECK) {
                /*
                 * hardware failure, damaged tape or improper
                 * operating conditions
                 */
                switch (sense[3]) {
                case 0x23:
                        /* a read data check occurred */
                        if ((sense[2] & SENSE_TAPE_SYNC_MODE) ||
                            inhibit_cu_recovery)
                                // data check is not permanent, may be
                                // recovered. We always use async-mode with
                                // cu-recovery, so this should *never* happen.
                                return tape_34xx_erp_bug(device, request,
                                                         irb, -4);

                        /* data check is permanent, CU recovery has failed */
                        dev_warn (&device->cdev->dev, "A read error occurred "
                                "that cannot be recovered\n");
                        return tape_34xx_erp_failed(request, -EIO);
                case 0x25:
                        // a write data check occurred
                        if ((sense[2] & SENSE_TAPE_SYNC_MODE) ||
                            inhibit_cu_recovery)
                                // data check is not permanent, may be
                                // recovered. We always use async-mode with
                                // cu-recovery, so this should *never* happen.
                                return tape_34xx_erp_bug(device, request,
                                                         irb, -5);

                        // data check is permanent, cu-recovery has failed
                        dev_warn (&device->cdev->dev, "A write error on the "
                                "tape cannot be recovered\n");
                        return tape_34xx_erp_failed(request, -EIO);
                case 0x26:
                        /* Data Check (read opposite) occurred. */
                        return tape_34xx_erp_read_opposite(device, request);
                case 0x28:
                        /* ID-Mark at tape start couldn't be written */
                        dev_warn (&device->cdev->dev, "Writing the ID-mark "
                                "failed\n");
                        return tape_34xx_erp_failed(request, -EIO);
                case 0x31:
                        /* Tape void. Tried to read beyond end of device. */
                        dev_warn (&device->cdev->dev, "Reading the tape beyond"
                                " the end of the recorded area failed\n");
                        return tape_34xx_erp_failed(request, -ENOSPC);
                case 0x41:
                        /* Record sequence error. */
                        dev_warn (&device->cdev->dev, "The tape contains an "
                                "incorrect block ID sequence\n");
                        return tape_34xx_erp_failed(request, -EIO);
                default:
                        /* all data checks for 3480 should result in one of
                         * the above erpa-codes. For 3490, other data-check
                         * conditions do exist. */
                        if (device->cdev->id.driver_info == tape_3480)
                                return tape_34xx_erp_bug(device, request,
                                                         irb, -6);
                }
        }

        if (sense[0] & SENSE_OVERRUN)
                return tape_34xx_erp_overrun(device, request, irb);

        if (sense[1] & SENSE_RECORD_SEQUENCE_ERR)
                return tape_34xx_erp_sequence(device, request, irb);

        /* Sensing erpa codes */
        switch (sense[3]) {
        case 0x00:
                /* Unit check with erpa code 0. Report and ignore. */
                return TAPE_IO_SUCCESS;
        case 0x21:
                /*
                 * Data streaming not operational. CU will switch to
                 * interlock mode. Reissue the command.
                 */
                return tape_34xx_erp_retry(request);
        case 0x22:
                /*
                 * Path equipment check. Might be drive adapter error, buffer
                 * error on the lower interface, internal path not usable,
                 * or error during cartridge load.
                 */
                dev_warn (&device->cdev->dev, "A path equipment check occurred"
                        " for the tape device\n");
                return tape_34xx_erp_failed(request, -EIO);
        case 0x24:
                /*
                 * Load display check. Load display was command was issued,
                 * but the drive is displaying a drive check message. Can
                 * be threated as "device end".
                 */
                return tape_34xx_erp_succeeded(request);
        case 0x27:
                /*
                 * Command reject. May indicate illegal channel program or
                 * buffer over/underrun. Since all channel programs are
                 * issued by this driver and ought be correct, we assume a
                 * over/underrun situation and retry the channel program.
                 */
                return tape_34xx_erp_retry(request);
        case 0x29:
                /*
                 * Function incompatible. Either the tape is idrc compressed
                 * but the hardware isn't capable to do idrc, or a perform
                 * subsystem func is issued and the CU is not on-line.
                 */
                return tape_34xx_erp_failed(request, -EIO);
        case 0x2a:
                /*
                 * Unsolicited environmental data. An internal counter
                 * overflows, we can ignore this and reissue the cmd.
                 */
                return tape_34xx_erp_retry(request);
        case 0x2b:
                /*
                 * Environmental data present. Indicates either unload
                 * completed ok or read buffered log command completed ok.
                 */
                if (request->op == TO_RUN) {
                        /* Rewind unload completed ok. */
                        tape_med_state_set(device, MS_UNLOADED);
                        return tape_34xx_erp_succeeded(request);
                }
                /* tape_34xx doesn't use read buffered log commands. */
                return tape_34xx_erp_bug(device, request, irb, sense[3]);
        case 0x2c:
                /*
                 * Permanent equipment check. CU has tried recovery, but
                 * did not succeed.
                 */
                return tape_34xx_erp_failed(request, -EIO);
        case 0x2d:
                /* Data security erase failure. */
                if (request->op == TO_DSE)
                        return tape_34xx_erp_failed(request, -EIO);
                /* Data security erase failure, but no such command issued. */
                return tape_34xx_erp_bug(device, request, irb, sense[3]);
        case 0x2e:
                /*
                 * Not capable. This indicates either that the drive fails
                 * reading the format id mark or that that format specified
                 * is not supported by the drive.
                 */
                dev_warn (&device->cdev->dev, "The tape unit cannot process "
                        "the tape format\n");
                return tape_34xx_erp_failed(request, -EMEDIUMTYPE);
        case 0x30:
                /* The medium is write protected. */
                dev_warn (&device->cdev->dev, "The tape medium is write-"
                        "protected\n");
                return tape_34xx_erp_failed(request, -EACCES);
        case 0x32:
                // Tension loss. We cannot recover this, it's an I/O error.
                dev_warn (&device->cdev->dev, "The tape does not have the "
                        "required tape tension\n");
                return tape_34xx_erp_failed(request, -EIO);
        case 0x33:
                /*
                 * Load Failure. The cartridge was not inserted correctly or
                 * the tape is not threaded correctly.
                 */
                dev_warn (&device->cdev->dev, "The tape unit failed to load"
                        " the cartridge\n");
                tape_34xx_delete_sbid_from(device, 0);
                return tape_34xx_erp_failed(request, -EIO);
        case 0x34:
                /*
                 * Unload failure. The drive cannot maintain tape tension
                 * and control tape movement during an unload operation.
                 */
                dev_warn (&device->cdev->dev, "Automatic unloading of the tape"
                        " cartridge failed\n");
                if (request->op == TO_RUN)
                        return tape_34xx_erp_failed(request, -EIO);
                return tape_34xx_erp_bug(device, request, irb, sense[3]);
        case 0x35:
                /*
                 * Drive equipment check. One of the following:
                 * - cu cannot recover from a drive detected error
                 * - a check code message is shown on drive display
                 * - the cartridge loader does not respond correctly
                 * - a failure occurs during an index, load, or unload cycle
                 */
                dev_warn (&device->cdev->dev, "An equipment check has occurred"
                        " on the tape unit\n");
                return tape_34xx_erp_failed(request, -EIO);
        case 0x36:
                if (device->cdev->id.driver_info == tape_3490)
                        /* End of data. */
                        return tape_34xx_erp_failed(request, -EIO);
                /* This erpa is reserved for 3480 */
                return tape_34xx_erp_bug(device, request, irb, sense[3]);
        case 0x37:
                /*
                 * Tape length error. The tape is shorter than reported in
                 * the beginning-of-tape data.
                 */
                dev_warn (&device->cdev->dev, "The tape information states an"
                        " incorrect length\n");
                return tape_34xx_erp_failed(request, -EIO);
        case 0x38:
                /*
                 * Physical end of tape. A read/write operation reached
                 * the physical end of tape.
                 */
                if (request->op==TO_WRI ||
                    request->op==TO_DSE ||
                    request->op==TO_WTM)
                        return tape_34xx_erp_failed(request, -ENOSPC);
                return tape_34xx_erp_failed(request, -EIO);
        case 0x39:
                /* Backward at Beginning of tape. */
                return tape_34xx_erp_failed(request, -EIO);
        case 0x3a:
                /* Drive switched to not ready. */
                dev_warn (&device->cdev->dev, "The tape unit is not ready\n");
                return tape_34xx_erp_failed(request, -EIO);
        case 0x3b:
                /* Manual rewind or unload. This causes an I/O error. */
                dev_warn (&device->cdev->dev, "The tape medium has been "
                        "rewound or unloaded manually\n");
                tape_34xx_delete_sbid_from(device, 0);
                return tape_34xx_erp_failed(request, -EIO);
        case 0x42:
                /*
                 * Degraded mode. A condition that can cause degraded
                 * performance is detected.
                 */
                dev_warn (&device->cdev->dev, "The tape subsystem is running "
                        "in degraded mode\n");
                return tape_34xx_erp_retry(request);
        case 0x43:
                /* Drive not ready. */
                tape_34xx_delete_sbid_from(device, 0);
                tape_med_state_set(device, MS_UNLOADED);
                /* Some commands commands are successful even in this case */
                if (sense[1] & SENSE_DRIVE_ONLINE) {
                        switch(request->op) {
                                case TO_ASSIGN:
                                case TO_UNASSIGN:
                                case TO_DIS:
                                case TO_NOP:
                                        return tape_34xx_done(request);
                                        break;
                                default:
                                        break;
                        }
                }
                return tape_34xx_erp_failed(request, -ENOMEDIUM);
        case 0x44:
                /* Locate Block unsuccessful. */
                if (request->op != TO_BLOCK && request->op != TO_LBL)
                        /* No locate block was issued. */
                        return tape_34xx_erp_bug(device, request,
                                                 irb, sense[3]);
                return tape_34xx_erp_failed(request, -EIO);
        case 0x45:
                /* The drive is assigned to a different channel path. */
                dev_warn (&device->cdev->dev, "The tape unit is already "
                        "assigned\n");
                return tape_34xx_erp_failed(request, -EIO);
        case 0x46:
                /*
                 * Drive not on-line. Drive may be switched offline,
                 * the power supply may be switched off or
                 * the drive address may not be set correctly.
                 */
                dev_warn (&device->cdev->dev, "The tape unit is not online\n");
                return tape_34xx_erp_failed(request, -EIO);
        case 0x47:
                /* Volume fenced. CU reports volume integrity is lost. */
                dev_warn (&device->cdev->dev, "The control unit has fenced "
                        "access to the tape volume\n");
                tape_34xx_delete_sbid_from(device, 0);
                return tape_34xx_erp_failed(request, -EIO);
        case 0x48:
                /* Log sense data and retry request. */
                return tape_34xx_erp_retry(request);
        case 0x49:
                /* Bus out check. A parity check error on the bus was found. */
                dev_warn (&device->cdev->dev, "A parity error occurred on the "
                        "tape bus\n");
                return tape_34xx_erp_failed(request, -EIO);
        case 0x4a:
                /* Control unit erp failed. */
                dev_warn (&device->cdev->dev, "I/O error recovery failed on "
                        "the tape control unit\n");
                return tape_34xx_erp_failed(request, -EIO);
        case 0x4b:
                /*
                 * CU and drive incompatible. The drive requests micro-program
                 * patches, which are not available on the CU.
                 */
                dev_warn (&device->cdev->dev, "The tape unit requires a "
                        "firmware update\n");
                return tape_34xx_erp_failed(request, -EIO);
        case 0x4c:
                /*
                 * Recovered Check-One failure. Cu develops a hardware error,
                 * but is able to recover.
                 */
                return tape_34xx_erp_retry(request);
        case 0x4d:
                if (device->cdev->id.driver_info == tape_3490)
                        /*
                         * Resetting event received. Since the driver does
                         * not support resetting event recovery (which has to
                         * be handled by the I/O Layer), retry our command.
                         */
                        return tape_34xx_erp_retry(request);
                /* This erpa is reserved for 3480. */
                return tape_34xx_erp_bug(device, request, irb, sense[3]);
        case 0x4e:
                if (device->cdev->id.driver_info == tape_3490) {
                        /*
                         * Maximum block size exceeded. This indicates, that
                         * the block to be written is larger than allowed for
                         * buffered mode.
                         */
                        dev_warn (&device->cdev->dev, "The maximum block size"
                                " for buffered mode is exceeded\n");
                        return tape_34xx_erp_failed(request, -ENOBUFS);
                }
                /* This erpa is reserved for 3480. */
                return tape_34xx_erp_bug(device, request, irb, sense[3]);
        case 0x50:
                /*
                 * Read buffered log (Overflow). CU is running in extended
                 * buffered log mode, and a counter overflows. This should
                 * never happen, since we're never running in extended
                 * buffered log mode.
                 */
                return tape_34xx_erp_retry(request);
        case 0x51:
                /*
                 * Read buffered log (EOV). EOF processing occurs while the
                 * CU is in extended buffered log mode. This should never
                 * happen, since we're never running in extended buffered
                 * log mode.
                 */
                return tape_34xx_erp_retry(request);
        case 0x52:
                /* End of Volume complete. Rewind unload completed ok. */
                if (request->op == TO_RUN) {
                        tape_med_state_set(device, MS_UNLOADED);
                        tape_34xx_delete_sbid_from(device, 0);
                        return tape_34xx_erp_succeeded(request);
                }
                return tape_34xx_erp_bug(device, request, irb, sense[3]);
        case 0x53:
                /* Global command intercept. */
                return tape_34xx_erp_retry(request);
        case 0x54:
                /* Channel interface recovery (temporary). */
                return tape_34xx_erp_retry(request);
        case 0x55:
                /* Channel interface recovery (permanent). */
                dev_warn (&device->cdev->dev, "A channel interface error cannot be"
                        " recovered\n");
                return tape_34xx_erp_failed(request, -EIO);
        case 0x56:
                /* Channel protocol error. */
                dev_warn (&device->cdev->dev, "A channel protocol error "
                        "occurred\n");
                return tape_34xx_erp_failed(request, -EIO);
        case 0x57:
                /*
                 * 3480: Attention intercept.
                 * 3490: Global status intercept.
                 */
                return tape_34xx_erp_retry(request);
        case 0x5a:
                /*
                 * Tape length incompatible. The tape inserted is too long,
                 * which could cause damage to the tape or the drive.
                 */
                dev_warn (&device->cdev->dev, "The tape unit does not support "
                        "the tape length\n");
                return tape_34xx_erp_failed(request, -EIO);
        case 0x5b:
                /* Format 3480 XF incompatible */
                if (sense[1] & SENSE_BEGINNING_OF_TAPE)
                        /* The tape will get overwritten. */
                        return tape_34xx_erp_retry(request);
                dev_warn (&device->cdev->dev, "The tape unit does not support"
                        " format 3480 XF\n");
                return tape_34xx_erp_failed(request, -EIO);
        case 0x5c:
                /* Format 3480-2 XF incompatible */
                dev_warn (&device->cdev->dev, "The tape unit does not support tape "
                        "format 3480-2 XF\n");
                return tape_34xx_erp_failed(request, -EIO);
        case 0x5d:
                /* Tape length violation. */
                dev_warn (&device->cdev->dev, "The tape unit does not support"
                        " the current tape length\n");
                return tape_34xx_erp_failed(request, -EMEDIUMTYPE);
        case 0x5e:
                /* Compaction algorithm incompatible. */
                dev_warn (&device->cdev->dev, "The tape unit does not support"
                        " the compaction algorithm\n");
                return tape_34xx_erp_failed(request, -EMEDIUMTYPE);

                /* The following erpas should have been covered earlier. */
        case 0x23: /* Read data check. */
        case 0x25: /* Write data check. */
        case 0x26: /* Data check (read opposite). */
        case 0x28: /* Write id mark check. */
        case 0x31: /* Tape void. */
        case 0x40: /* Overrun error. */
        case 0x41: /* Record sequence error. */
                /* All other erpas are reserved for future use. */
        default:
                return tape_34xx_erp_bug(device, request, irb, sense[3]);
        }
}

/*
 * 3480/3490 interrupt handler
 */
static int
tape_34xx_irq(struct tape_device *device, struct tape_request *request,
              struct irb *irb)
{
        if (request == NULL)
                return tape_34xx_unsolicited_irq(device, irb);

        if ((irb->scsw.cmd.dstat & DEV_STAT_UNIT_EXCEP) &&
            (irb->scsw.cmd.dstat & DEV_STAT_DEV_END) &&
            (request->op == TO_WRI)) {
                /* Write at end of volume */
                return tape_34xx_erp_failed(request, -ENOSPC);
        }

        if (irb->scsw.cmd.dstat & DEV_STAT_UNIT_CHECK)
                return tape_34xx_unit_check(device, request, irb);

        if (irb->scsw.cmd.dstat & DEV_STAT_DEV_END) {
                /*
                 * A unit exception occurs on skipping over a tapemark block.
                 */
                if (irb->scsw.cmd.dstat & DEV_STAT_UNIT_EXCEP) {
                        if (request->op == TO_BSB || request->op == TO_FSB)
                                request->rescnt++;
                        else
                                DBF_EVENT(5, "Unit Exception!\n");
                }
                return tape_34xx_done(request);
        }

        DBF_EVENT(6, "xunknownirq\n");
        tape_dump_sense_dbf(device, request, irb);
        return TAPE_IO_STOP;
}

/*
 * ioctl_overload
 */
static int
tape_34xx_ioctl(struct tape_device *device, unsigned int cmd, unsigned long arg)
{
        if (cmd == TAPE390_DISPLAY) {
                struct display_struct disp;

                if (copy_from_user(&disp, (char __user *) arg, sizeof(disp)) != 0)
                        return -EFAULT;

                return tape_std_display(device, &disp);
        } else
                return -EINVAL;
}

static inline void
tape_34xx_append_new_sbid(struct tape_34xx_block_id bid, struct list_head *l)
{
        struct tape_34xx_sbid * new_sbid;

        new_sbid = kmalloc(sizeof(*new_sbid), GFP_ATOMIC);
        if (!new_sbid)
                return;

        new_sbid->bid = bid;
        list_add(&new_sbid->list, l);
}

/*
 * Build up the search block ID list. The block ID consists of a logical
 * block number and a hardware specific part. The hardware specific part
 * helps the tape drive to speed up searching for a specific block.
 */
static void
tape_34xx_add_sbid(struct tape_device *device, struct tape_34xx_block_id bid)
{
        struct list_head *      sbid_list;
        struct tape_34xx_sbid * sbid;
        struct list_head *      l;

        /*
         * immediately return if there is no list at all or the block to add
         * is located in segment 1 of wrap 0 because this position is used
         * if no hardware position data is supplied.
         */
        sbid_list = (struct list_head *) device->discdata;
        if (!sbid_list || (bid.segment < 2 && bid.wrap == 0))
                return;

        /*
         * Search the position where to insert the new entry. Hardware
         * acceleration uses only the segment and wrap number. So we
         * need only one entry for a specific wrap/segment combination.
         * If there is a block with a lower number but the same hard-
         * ware position data we just update the block number in the
         * existing entry.
         */
        list_for_each(l, sbid_list) {
                sbid = list_entry(l, struct tape_34xx_sbid, list);

                if (
                        (sbid->bid.segment == bid.segment) &&
                        (sbid->bid.wrap    == bid.wrap)
                ) {
                        if (bid.block < sbid->bid.block)
                                sbid->bid = bid;
                        else return;
                        break;
                }

                /* Sort in according to logical block number. */
                if (bid.block < sbid->bid.block) {
                        tape_34xx_append_new_sbid(bid, l->prev);
                        break;
                }
        }
        /* List empty or new block bigger than last entry. */
        if (l == sbid_list)
                tape_34xx_append_new_sbid(bid, l->prev);

        DBF_LH(4, "Current list is:\n");
        list_for_each(l, sbid_list) {
                sbid = list_entry(l, struct tape_34xx_sbid, list);
                DBF_LH(4, "%d:%03d@%05d\n",
                        sbid->bid.wrap,
                        sbid->bid.segment,
                        sbid->bid.block
                );
        }
}

/*
 * Delete all entries from the search block ID list that belong to tape blocks
 * equal or higher than the given number.
 */
static void
tape_34xx_delete_sbid_from(struct tape_device *device, int from)
{
        struct list_head *      sbid_list;
        struct tape_34xx_sbid * sbid;
        struct list_head *      l;
        struct list_head *      n;

        sbid_list = (struct list_head *) device->discdata;
        if (!sbid_list)
                return;

        list_for_each_safe(l, n, sbid_list) {
                sbid = list_entry(l, struct tape_34xx_sbid, list);
                if (sbid->bid.block >= from) {
                        DBF_LH(4, "Delete sbid %d:%03d@%05d\n",
                                sbid->bid.wrap,
                                sbid->bid.segment,
                                sbid->bid.block
                        );
                        list_del(l);
                        kfree(sbid);
                }
        }
}

/*
 * Merge hardware position data into a block id.
 */
static void
tape_34xx_merge_sbid(
        struct tape_device *            device,
        struct tape_34xx_block_id *     bid
) {
        struct tape_34xx_sbid * sbid;
        struct tape_34xx_sbid * sbid_to_use;
        struct list_head *      sbid_list;
        struct list_head *      l;

        sbid_list = (struct list_head *) device->discdata;
        bid->wrap    = 0;
        bid->segment = 1;

        if (!sbid_list || list_empty(sbid_list))
                return;

        sbid_to_use = NULL;
        list_for_each(l, sbid_list) {
                sbid = list_entry(l, struct tape_34xx_sbid, list);

                if (sbid->bid.block >= bid->block)
                        break;
                sbid_to_use = sbid;
        }
        if (sbid_to_use) {
                bid->wrap    = sbid_to_use->bid.wrap;
                bid->segment = sbid_to_use->bid.segment;
                DBF_LH(4, "Use %d:%03d@%05d for %05d\n",
                        sbid_to_use->bid.wrap,
                        sbid_to_use->bid.segment,
                        sbid_to_use->bid.block,
                        bid->block
                );
        }
}

static int
tape_34xx_setup_device(struct tape_device * device)
{
        int                     rc;
        struct list_head *      discdata;

        DBF_EVENT(6, "34xx device setup\n");
        if ((rc = tape_std_assign(device)) == 0) {
                if ((rc = tape_34xx_medium_sense(device)) != 0) {
                        DBF_LH(3, "34xx medium sense returned %d\n", rc);
                }
        }
        discdata = kmalloc(sizeof(struct list_head), GFP_KERNEL);
        if (discdata) {
                        INIT_LIST_HEAD(discdata);
                        device->discdata = discdata;
        }

        return rc;
}

static void
tape_34xx_cleanup_device(struct tape_device *device)
{
        tape_std_unassign(device);
        
        if (device->discdata) {
                tape_34xx_delete_sbid_from(device, 0);
                kfree(device->discdata);
                device->discdata = NULL;
        }
}


/*
 * MTTELL: Tell block. Return the number of block relative to current file.
 */
static int
tape_34xx_mttell(struct tape_device *device, int mt_count)
{
        struct {
                struct tape_34xx_block_id       cbid;
                struct tape_34xx_block_id       dbid;
        } __attribute__ ((packed)) block_id;
        int rc;

        rc = tape_std_read_block_id(device, (__u64 *) &block_id);
        if (rc)
                return rc;

        tape_34xx_add_sbid(device, block_id.cbid);
        return block_id.cbid.block;
}

/*
 * MTSEEK: seek to the specified block.
 */
static int
tape_34xx_mtseek(struct tape_device *device, int mt_count)
{
        struct tape_request *request;
        struct tape_34xx_block_id *     bid;

        if (mt_count > 0x3fffff) {
                DBF_EXCEPTION(6, "xsee parm\n");
                return -EINVAL;
        }
        request = tape_alloc_request(3, 4);
        if (IS_ERR(request))
                return PTR_ERR(request);

        /* setup ccws */
        request->op = TO_LBL;
        bid         = (struct tape_34xx_block_id *) request->cpdata;
        bid->format = (*device->modeset_byte & 0x08) ?
                        TAPE34XX_FMT_3480_XF : TAPE34XX_FMT_3480;
        bid->block  = mt_count;
        tape_34xx_merge_sbid(device, bid);

        tape_ccw_cc(request->cpaddr, MODE_SET_DB, 1, device->modeset_byte);
        tape_ccw_cc(request->cpaddr + 1, LOCATE, 4, request->cpdata);
        tape_ccw_end(request->cpaddr + 2, NOP, 0, NULL);

        /* execute it */
        return tape_do_io_free(device, request);
}

/*
 * List of 3480/3490 magnetic tape commands.
 */
static tape_mtop_fn tape_34xx_mtop[TAPE_NR_MTOPS] = {
        [MTRESET]        = tape_std_mtreset,
        [MTFSF]          = tape_std_mtfsf,
        [MTBSF]          = tape_std_mtbsf,
        [MTFSR]          = tape_std_mtfsr,
        [MTBSR]          = tape_std_mtbsr,
        [MTWEOF]         = tape_std_mtweof,
        [MTREW]          = tape_std_mtrew,
        [MTOFFL]         = tape_std_mtoffl,
        [MTNOP]          = tape_std_mtnop,
        [MTRETEN]        = tape_std_mtreten,
        [MTBSFM]         = tape_std_mtbsfm,
        [MTFSFM]         = tape_std_mtfsfm,
        [MTEOM]          = tape_std_mteom,
        [MTERASE]        = tape_std_mterase,
        [MTRAS1]         = NULL,
        [MTRAS2]         = NULL,
        [MTRAS3]         = NULL,
        [MTSETBLK]       = tape_std_mtsetblk,
        [MTSETDENSITY]   = NULL,
        [MTSEEK]         = tape_34xx_mtseek,
        [MTTELL]         = tape_34xx_mttell,
        [MTSETDRVBUFFER] = NULL,
        [MTFSS]          = NULL,
        [MTBSS]          = NULL,
        [MTWSM]          = NULL,
        [MTLOCK]         = NULL,
        [MTUNLOCK]       = NULL,
        [MTLOAD]         = tape_std_mtload,
        [MTUNLOAD]       = tape_std_mtunload,
        [MTCOMPRESSION]  = tape_std_mtcompression,
        [MTSETPART]      = NULL,
        [MTMKPART]       = NULL
};

/*
 * Tape discipline structure for 3480 and 3490.
 */
static struct tape_discipline tape_discipline_34xx = {
        .owner = THIS_MODULE,
        .setup_device = tape_34xx_setup_device,
        .cleanup_device = tape_34xx_cleanup_device,
        .process_eov = tape_std_process_eov,
        .irq = tape_34xx_irq,
        .read_block = tape_std_read_block,
        .write_block = tape_std_write_block,
        .ioctl_fn = tape_34xx_ioctl,
        .mtop_array = tape_34xx_mtop
};

static struct ccw_device_id tape_34xx_ids[] = {
        { CCW_DEVICE_DEVTYPE(0x3480, 0, 0x3480, 0), .driver_info = tape_3480},
        { CCW_DEVICE_DEVTYPE(0x3490, 0, 0x3490, 0), .driver_info = tape_3490},
        { /* end of list */ },
};

static int
tape_34xx_online(struct ccw_device *cdev)
{
        return tape_generic_online(
                dev_get_drvdata(&cdev->dev),
                &tape_discipline_34xx
        );
}

static struct ccw_driver tape_34xx_driver = {
        .driver = {
                .name = "tape_34xx",
                .owner = THIS_MODULE,
        },
        .ids = tape_34xx_ids,
        .probe = tape_generic_probe,
        .remove = tape_generic_remove,
        .set_online = tape_34xx_online,
        .set_offline = tape_generic_offline,
        .freeze = tape_generic_pm_suspend,
        .int_class = IRQIO_TAP,
};

static int
tape_34xx_init (void)
{
        int rc;

        TAPE_DBF_AREA = debug_register ( "tape_34xx", 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, "34xx init\n");
        /* Register driver for 3480/3490 tapes. */
        rc = ccw_driver_register(&tape_34xx_driver);
        if (rc)
                DBF_EVENT(3, "34xx init failed\n");
        else
                DBF_EVENT(3, "34xx registered\n");
        return rc;
}

static void
tape_34xx_exit(void)
{
        ccw_driver_unregister(&tape_34xx_driver);

        debug_unregister(TAPE_DBF_AREA);
}

MODULE_DEVICE_TABLE(ccw, tape_34xx_ids);
MODULE_AUTHOR("(C) 2001-2002 IBM Deutschland Entwicklung GmbH");
MODULE_DESCRIPTION("Linux on zSeries channel attached 3480 tape device driver");
MODULE_LICENSE("GPL");

module_init(tape_34xx_init);
module_exit(tape_34xx_exit);