/*
 * File...........: linux/drivers/s390/block/dasd.c
 * Author(s)......: Holger Smolinski <Holger.Smolinski@de.ibm.com>
 *                  Horst Hummel <Horst.Hummel@de.ibm.com>
 *                  Carsten Otte <Cotte@de.ibm.com>
 *                  Martin Schwidefsky <schwidefsky@de.ibm.com>
 * Bugreports.to..: <Linux390@de.ibm.com>
 * (C) IBM Corporation, IBM Deutschland Entwicklung GmbH, 1999-2001
 *
 */

#include <linux/kmod.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/ctype.h>
#include <linux/major.h>
#include <linux/slab.h>
#include <linux/buffer_head.h>
#include <linux/hdreg.h>

#include <asm/ccwdev.h>
#include <asm/ebcdic.h>
#include <asm/idals.h>
#include <asm/todclk.h>

/* This is ugly... */
#define PRINTK_HEADER "dasd:"

#include "dasd_int.h"
/*
 * SECTION: Constant definitions to be used within this file
 */
#define DASD_CHANQ_MAX_SIZE 4

/*
 * SECTION: exported variables of dasd.c
 */
debug_info_t *dasd_debug_area;
struct dasd_discipline *dasd_diag_discipline_pointer;
void dasd_int_handler(struct ccw_device *, unsigned long, struct irb *);

MODULE_AUTHOR("Holger Smolinski <Holger.Smolinski@de.ibm.com>");
MODULE_DESCRIPTION("Linux on S/390 DASD device driver,"
                   " Copyright 2000 IBM Corporation");
MODULE_SUPPORTED_DEVICE("dasd");
MODULE_LICENSE("GPL");

/*
 * SECTION: prototypes for static functions of dasd.c
 */
static int  dasd_alloc_queue(struct dasd_device * device);
static void dasd_setup_queue(struct dasd_device * device);
static void dasd_free_queue(struct dasd_device * device);
static void dasd_flush_request_queue(struct dasd_device *);
static int dasd_flush_ccw_queue(struct dasd_device *, int);
static void dasd_tasklet(struct dasd_device *);
static void do_kick_device(struct work_struct *);

/*
 * SECTION: Operations on the device structure.
 */
static wait_queue_head_t dasd_init_waitq;
static wait_queue_head_t dasd_flush_wq;

/*
 * Allocate memory for a new device structure.
 */
struct dasd_device *
dasd_alloc_device(void)
{
        struct dasd_device *device;

        device = kzalloc(sizeof (struct dasd_device), GFP_ATOMIC);
        if (device == NULL)
                return ERR_PTR(-ENOMEM);
        /* open_count = 0 means device online but not in use */
        atomic_set(&device->open_count, -1);

        /* Get two pages for normal block device operations. */
        device->ccw_mem = (void *) __get_free_pages(GFP_ATOMIC | GFP_DMA, 1);
        if (device->ccw_mem == NULL) {
                kfree(device);
                return ERR_PTR(-ENOMEM);
        }
        /* Get one page for error recovery. */
        device->erp_mem = (void *) get_zeroed_page(GFP_ATOMIC | GFP_DMA);
        if (device->erp_mem == NULL) {
                free_pages((unsigned long) device->ccw_mem, 1);
                kfree(device);
                return ERR_PTR(-ENOMEM);
        }

        dasd_init_chunklist(&device->ccw_chunks, device->ccw_mem, PAGE_SIZE*2);
        dasd_init_chunklist(&device->erp_chunks, device->erp_mem, PAGE_SIZE);
        spin_lock_init(&device->mem_lock);
        spin_lock_init(&device->request_queue_lock);
        atomic_set (&device->tasklet_scheduled, 0);
        tasklet_init(&device->tasklet,
                     (void (*)(unsigned long)) dasd_tasklet,
                     (unsigned long) device);
        INIT_LIST_HEAD(&device->ccw_queue);
        init_timer(&device->timer);
        INIT_WORK(&device->kick_work, do_kick_device);
        device->state = DASD_STATE_NEW;
        device->target = DASD_STATE_NEW;

        return device;
}

/*
 * Free memory of a device structure.
 */
void
dasd_free_device(struct dasd_device *device)
{
        kfree(device->private);
        free_page((unsigned long) device->erp_mem);
        free_pages((unsigned long) device->ccw_mem, 1);
        kfree(device);
}

/*
 * Make a new device known to the system.
 */
static int
dasd_state_new_to_known(struct dasd_device *device)
{
        int rc;

        /*
         * As long as the device is not in state DASD_STATE_NEW we want to
         * keep the reference count > 0.
         */
        dasd_get_device(device);

        rc = dasd_alloc_queue(device);
        if (rc) {
                dasd_put_device(device);
                return rc;
        }

        device->state = DASD_STATE_KNOWN;
        return 0;
}

/*
 * Let the system forget about a device.
 */
static int
dasd_state_known_to_new(struct dasd_device * device)
{
        /* Disable extended error reporting for this device. */
        dasd_eer_disable(device);
        /* Forget the discipline information. */
        if (device->discipline)
                module_put(device->discipline->owner);
        device->discipline = NULL;
        if (device->base_discipline)
                module_put(device->base_discipline->owner);
        device->base_discipline = NULL;
        device->state = DASD_STATE_NEW;

        dasd_free_queue(device);

        /* Give up reference we took in dasd_state_new_to_known. */
        dasd_put_device(device);
        return 0;
}

/*
 * Request the irq line for the device.
 */
static int
dasd_state_known_to_basic(struct dasd_device * device)
{
        int rc;

        /* Allocate and register gendisk structure. */
        rc = dasd_gendisk_alloc(device);
        if (rc)
                return rc;

        /* register 'device' debug area, used for all DBF_DEV_XXX calls */
        device->debug_area = debug_register(device->cdev->dev.bus_id, 1, 2,
                                            8 * sizeof (long));
        debug_register_view(device->debug_area, &debug_sprintf_view);
        debug_set_level(device->debug_area, DBF_WARNING);
        DBF_DEV_EVENT(DBF_EMERG, device, "%s", "debug area created");

        device->state = DASD_STATE_BASIC;
        return 0;
}

/*
 * Release the irq line for the device. Terminate any running i/o.
 */
static int
dasd_state_basic_to_known(struct dasd_device * device)
{
        int rc;

        dasd_gendisk_free(device);
        rc = dasd_flush_ccw_queue(device, 1);
        if (rc)
                return rc;
        dasd_clear_timer(device);

        DBF_DEV_EVENT(DBF_EMERG, device, "%p debug area deleted", device);
        if (device->debug_area != NULL) {
                debug_unregister(device->debug_area);
                device->debug_area = NULL;
        }
        device->state = DASD_STATE_KNOWN;
        return 0;
}

/*
 * Do the initial analysis. The do_analysis function may return
 * -EAGAIN in which case the device keeps the state DASD_STATE_BASIC
 * until the discipline decides to continue the startup sequence
 * by calling the function dasd_change_state. The eckd disciplines
 * uses this to start a ccw that detects the format. The completion
 * interrupt for this detection ccw uses the kernel event daemon to
 * trigger the call to dasd_change_state. All this is done in the
 * discipline code, see dasd_eckd.c.
 * After the analysis ccw is done (do_analysis returned 0) the block
 * device is setup.
 * In case the analysis returns an error, the device setup is stopped
 * (a fake disk was already added to allow formatting).
 */
static int
dasd_state_basic_to_ready(struct dasd_device * device)
{
        int rc;

        rc = 0;
        if (device->discipline->do_analysis != NULL)
                rc = device->discipline->do_analysis(device);
        if (rc) {
                if (rc != -EAGAIN)
                        device->state = DASD_STATE_UNFMT;
                return rc;
        }
        /* make disk known with correct capacity */
        dasd_setup_queue(device);
        set_capacity(device->gdp, device->blocks << device->s2b_shift);
        device->state = DASD_STATE_READY;
        rc = dasd_scan_partitions(device);
        if (rc)
                device->state = DASD_STATE_BASIC;
        return rc;
}

/*
 * Remove device from block device layer. Destroy dirty buffers.
 * Forget format information. Check if the target level is basic
 * and if it is create fake disk for formatting.
 */
static int
dasd_state_ready_to_basic(struct dasd_device * device)
{
        int rc;

        rc = dasd_flush_ccw_queue(device, 0);
        if (rc)
                return rc;
        dasd_destroy_partitions(device);
        dasd_flush_request_queue(device);
        device->blocks = 0;
        device->bp_block = 0;
        device->s2b_shift = 0;
        device->state = DASD_STATE_BASIC;
        return 0;
}

/*
 * Back to basic.
 */
static int
dasd_state_unfmt_to_basic(struct dasd_device * device)
{
        device->state = DASD_STATE_BASIC;
        return 0;
}

/*
 * Make the device online and schedule the bottom half to start
 * the requeueing of requests from the linux request queue to the
 * ccw queue.
 */
static int
dasd_state_ready_to_online(struct dasd_device * device)
{
        device->state = DASD_STATE_ONLINE;
        dasd_schedule_bh(device);
        return 0;
}

/*
 * Stop the requeueing of requests again.
 */
static int
dasd_state_online_to_ready(struct dasd_device * device)
{
        device->state = DASD_STATE_READY;
        return 0;
}

/*
 * Device startup state changes.
 */
static int
dasd_increase_state(struct dasd_device *device)
{
        int rc;

        rc = 0;
        if (device->state == DASD_STATE_NEW &&
            device->target >= DASD_STATE_KNOWN)
                rc = dasd_state_new_to_known(device);

        if (!rc &&
            device->state == DASD_STATE_KNOWN &&
            device->target >= DASD_STATE_BASIC)
                rc = dasd_state_known_to_basic(device);

        if (!rc &&
            device->state == DASD_STATE_BASIC &&
            device->target >= DASD_STATE_READY)
                rc = dasd_state_basic_to_ready(device);

        if (!rc &&
            device->state == DASD_STATE_UNFMT &&
            device->target > DASD_STATE_UNFMT)
                rc = -EPERM;

        if (!rc &&
            device->state == DASD_STATE_READY &&
            device->target >= DASD_STATE_ONLINE)
                rc = dasd_state_ready_to_online(device);

        return rc;
}

/*
 * Device shutdown state changes.
 */
static int
dasd_decrease_state(struct dasd_device *device)
{
        int rc;

        rc = 0;
        if (device->state == DASD_STATE_ONLINE &&
            device->target <= DASD_STATE_READY)
                rc = dasd_state_online_to_ready(device);

        if (!rc &&
            device->state == DASD_STATE_READY &&
            device->target <= DASD_STATE_BASIC)
                rc = dasd_state_ready_to_basic(device);

        if (!rc &&
            device->state == DASD_STATE_UNFMT &&
            device->target <= DASD_STATE_BASIC)
                rc = dasd_state_unfmt_to_basic(device);

        if (!rc &&
            device->state == DASD_STATE_BASIC &&
            device->target <= DASD_STATE_KNOWN)
                rc = dasd_state_basic_to_known(device);

        if (!rc &&
            device->state == DASD_STATE_KNOWN &&
            device->target <= DASD_STATE_NEW)
                rc = dasd_state_known_to_new(device);

        return rc;
}

/*
 * This is the main startup/shutdown routine.
 */
static void
dasd_change_state(struct dasd_device *device)
{
        int rc;

        if (device->state == device->target)
                /* Already where we want to go today... */
                return;
        if (device->state < device->target)
                rc = dasd_increase_state(device);
        else
                rc = dasd_decrease_state(device);
        if (rc && rc != -EAGAIN)
                device->target = device->state;

        if (device->state == device->target)
                wake_up(&dasd_init_waitq);

        /* let user-space know that the device status changed */
        kobject_uevent(&device->cdev->dev.kobj, KOBJ_CHANGE);
}

/*
 * Kick starter for devices that did not complete the startup/shutdown
 * procedure or were sleeping because of a pending state.
 * dasd_kick_device will schedule a call do do_kick_device to the kernel
 * event daemon.
 */
static void
do_kick_device(struct work_struct *work)
{
        struct dasd_device *device = container_of(work, struct dasd_device, kick_work);
        dasd_change_state(device);
        dasd_schedule_bh(device);
        dasd_put_device(device);
}

void
dasd_kick_device(struct dasd_device *device)
{
        dasd_get_device(device);
        /* queue call to dasd_kick_device to the kernel event daemon. */
        schedule_work(&device->kick_work);
}

/*
 * Set the target state for a device and starts the state change.
 */
void
dasd_set_target_state(struct dasd_device *device, int target)
{
        /* If we are in probeonly mode stop at DASD_STATE_READY. */
        if (dasd_probeonly && target > DASD_STATE_READY)
                target = DASD_STATE_READY;
        if (device->target != target) {
                if (device->state == target)
                        wake_up(&dasd_init_waitq);
                device->target = target;
        }
        if (device->state != device->target)
                dasd_change_state(device);
}

/*
 * Enable devices with device numbers in [from..to].
 */
static inline int
_wait_for_device(struct dasd_device *device)
{
        return (device->state == device->target);
}

void
dasd_enable_device(struct dasd_device *device)
{
        dasd_set_target_state(device, DASD_STATE_ONLINE);
        if (device->state <= DASD_STATE_KNOWN)
                /* No discipline for device found. */
                dasd_set_target_state(device, DASD_STATE_NEW);
        /* Now wait for the devices to come up. */
        wait_event(dasd_init_waitq, _wait_for_device(device));
}

/*
 * SECTION: device operation (interrupt handler, start i/o, term i/o ...)
 */
#ifdef CONFIG_DASD_PROFILE

struct dasd_profile_info_t dasd_global_profile;
unsigned int dasd_profile_level = DASD_PROFILE_OFF;

/*
 * Increments counter in global and local profiling structures.
 */
#define dasd_profile_counter(value, counter, device) \
{ \
        int index; \
        for (index = 0; index < 31 && value >> (2+index); index++); \
        dasd_global_profile.counter[index]++; \
        device->profile.counter[index]++; \
}

/*
 * Add profiling information for cqr before execution.
 */
static void
dasd_profile_start(struct dasd_device *device, struct dasd_ccw_req * cqr,
                   struct request *req)
{
        struct list_head *l;
        unsigned int counter;

        if (dasd_profile_level != DASD_PROFILE_ON)
                return;

        /* count the length of the chanq for statistics */
        counter = 0;
        list_for_each(l, &device->ccw_queue)
                if (++counter >= 31)
                        break;
        dasd_global_profile.dasd_io_nr_req[counter]++;
        device->profile.dasd_io_nr_req[counter]++;
}

/*
 * Add profiling information for cqr after execution.
 */
static void
dasd_profile_end(struct dasd_device *device, struct dasd_ccw_req * cqr,
                 struct request *req)
{
        long strtime, irqtime, endtime, tottime;        /* in microseconds */
        long tottimeps, sectors;

        if (dasd_profile_level != DASD_PROFILE_ON)
                return;

        sectors = req->nr_sectors;
        if (!cqr->buildclk || !cqr->startclk ||
            !cqr->stopclk || !cqr->endclk ||
            !sectors)
                return;

        strtime = ((cqr->startclk - cqr->buildclk) >> 12);
        irqtime = ((cqr->stopclk - cqr->startclk) >> 12);
        endtime = ((cqr->endclk - cqr->stopclk) >> 12);
        tottime = ((cqr->endclk - cqr->buildclk) >> 12);
        tottimeps = tottime / sectors;

        if (!dasd_global_profile.dasd_io_reqs)
                memset(&dasd_global_profile, 0,
                       sizeof (struct dasd_profile_info_t));
        dasd_global_profile.dasd_io_reqs++;
        dasd_global_profile.dasd_io_sects += sectors;

        if (!device->profile.dasd_io_reqs)
                memset(&device->profile, 0,
                       sizeof (struct dasd_profile_info_t));
        device->profile.dasd_io_reqs++;
        device->profile.dasd_io_sects += sectors;

        dasd_profile_counter(sectors, dasd_io_secs, device);
        dasd_profile_counter(tottime, dasd_io_times, device);
        dasd_profile_counter(tottimeps, dasd_io_timps, device);
        dasd_profile_counter(strtime, dasd_io_time1, device);
        dasd_profile_counter(irqtime, dasd_io_time2, device);
        dasd_profile_counter(irqtime / sectors, dasd_io_time2ps, device);
        dasd_profile_counter(endtime, dasd_io_time3, device);
}
#else
#define dasd_profile_start(device, cqr, req) do {} while (0)
#define dasd_profile_end(device, cqr, req) do {} while (0)
#endif                          /* CONFIG_DASD_PROFILE */

/*
 * Allocate memory for a channel program with 'cplength' channel
 * command words and 'datasize' additional space. There are two
 * variantes: 1) dasd_kmalloc_request uses kmalloc to get the needed
 * memory and 2) dasd_smalloc_request uses the static ccw memory
 * that gets allocated for each device.
 */
struct dasd_ccw_req *
dasd_kmalloc_request(char *magic, int cplength, int datasize,
                   struct dasd_device * device)
{
        struct dasd_ccw_req *cqr;

        /* Sanity checks */
        BUG_ON( magic == NULL || datasize > PAGE_SIZE ||
             (cplength*sizeof(struct ccw1)) > PAGE_SIZE);

        cqr = kzalloc(sizeof(struct dasd_ccw_req), GFP_ATOMIC);
        if (cqr == NULL)
                return ERR_PTR(-ENOMEM);
        cqr->cpaddr = NULL;
        if (cplength > 0) {
                cqr->cpaddr = kcalloc(cplength, sizeof(struct ccw1),
                                      GFP_ATOMIC | GFP_DMA);
                if (cqr->cpaddr == NULL) {
                        kfree(cqr);
                        return ERR_PTR(-ENOMEM);
                }
        }
        cqr->data = NULL;
        if (datasize > 0) {
                cqr->data = kzalloc(datasize, GFP_ATOMIC | GFP_DMA);
                if (cqr->data == NULL) {
                        kfree(cqr->cpaddr);
                        kfree(cqr);
                        return ERR_PTR(-ENOMEM);
                }
        }
        strncpy((char *) &cqr->magic, magic, 4);
        ASCEBC((char *) &cqr->magic, 4);
        set_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
        dasd_get_device(device);
        return cqr;
}

struct dasd_ccw_req *
dasd_smalloc_request(char *magic, int cplength, int datasize,
                   struct dasd_device * device)
{
        unsigned long flags;
        struct dasd_ccw_req *cqr;
        char *data;
        int size;

        /* Sanity checks */
        BUG_ON( magic == NULL || datasize > PAGE_SIZE ||
             (cplength*sizeof(struct ccw1)) > PAGE_SIZE);

        size = (sizeof(struct dasd_ccw_req) + 7L) & -8L;
        if (cplength > 0)
                size += cplength * sizeof(struct ccw1);
        if (datasize > 0)
                size += datasize;
        spin_lock_irqsave(&device->mem_lock, flags);
        cqr = (struct dasd_ccw_req *)
                dasd_alloc_chunk(&device->ccw_chunks, size);
        spin_unlock_irqrestore(&device->mem_lock, flags);
        if (cqr == NULL)
                return ERR_PTR(-ENOMEM);
        memset(cqr, 0, sizeof(struct dasd_ccw_req));
        data = (char *) cqr + ((sizeof(struct dasd_ccw_req) + 7L) & -8L);
        cqr->cpaddr = NULL;
        if (cplength > 0) {
                cqr->cpaddr = (struct ccw1 *) data;
                data += cplength*sizeof(struct ccw1);
                memset(cqr->cpaddr, 0, cplength*sizeof(struct ccw1));
        }
        cqr->data = NULL;
        if (datasize > 0) {
                cqr->data = data;
                memset(cqr->data, 0, datasize);
        }
        strncpy((char *) &cqr->magic, magic, 4);
        ASCEBC((char *) &cqr->magic, 4);
        set_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
        dasd_get_device(device);
        return cqr;
}

/*
 * Free memory of a channel program. This function needs to free all the
 * idal lists that might have been created by dasd_set_cda and the
 * struct dasd_ccw_req itself.
 */
void
dasd_kfree_request(struct dasd_ccw_req * cqr, struct dasd_device * device)
{
#ifdef CONFIG_64BIT
        struct ccw1 *ccw;

        /* Clear any idals used for the request. */
        ccw = cqr->cpaddr;
        do {
                clear_normalized_cda(ccw);
        } while (ccw++->flags & (CCW_FLAG_CC | CCW_FLAG_DC));
#endif
        kfree(cqr->cpaddr);
        kfree(cqr->data);
        kfree(cqr);
        dasd_put_device(device);
}

void
dasd_sfree_request(struct dasd_ccw_req * cqr, struct dasd_device * device)
{
        unsigned long flags;

        spin_lock_irqsave(&device->mem_lock, flags);
        dasd_free_chunk(&device->ccw_chunks, cqr);
        spin_unlock_irqrestore(&device->mem_lock, flags);
        dasd_put_device(device);
}

/*
 * Check discipline magic in cqr.
 */
static inline int
dasd_check_cqr(struct dasd_ccw_req *cqr)
{
        struct dasd_device *device;

        if (cqr == NULL)
                return -EINVAL;
        device = cqr->device;
        if (strncmp((char *) &cqr->magic, device->discipline->ebcname, 4)) {
                DEV_MESSAGE(KERN_WARNING, device,
                            " dasd_ccw_req 0x%08x magic doesn't match"
                            " discipline 0x%08x",
                            cqr->magic,
                            *(unsigned int *) device->discipline->name);
                return -EINVAL;
        }
        return 0;
}

/*
 * Terminate the current i/o and set the request to clear_pending.
 * Timer keeps device runnig.
 * ccw_device_clear can fail if the i/o subsystem
 * is in a bad mood.
 */
int
dasd_term_IO(struct dasd_ccw_req * cqr)
{
        struct dasd_device *device;
        int retries, rc;

        /* Check the cqr */
        rc = dasd_check_cqr(cqr);
        if (rc)
                return rc;
        retries = 0;
        device = (struct dasd_device *) cqr->device;
        while ((retries < 5) && (cqr->status == DASD_CQR_IN_IO)) {
                rc = ccw_device_clear(device->cdev, (long) cqr);
                switch (rc) {
                case 0: /* termination successful */
                        cqr->retries--;
                        cqr->status = DASD_CQR_CLEAR;
                        cqr->stopclk = get_clock();
                        cqr->starttime = 0;
                        DBF_DEV_EVENT(DBF_DEBUG, device,
                                      "terminate cqr %p successful",
                                      cqr);
                        break;
                case -ENODEV:
                        DBF_DEV_EVENT(DBF_ERR, device, "%s",
                                      "device gone, retry");
                        break;
                case -EIO:
                        DBF_DEV_EVENT(DBF_ERR, device, "%s",
                                      "I/O error, retry");
                        break;
                case -EINVAL:
                case -EBUSY:
                        DBF_DEV_EVENT(DBF_ERR, device, "%s",
                                      "device busy, retry later");
                        break;
                default:
                        DEV_MESSAGE(KERN_ERR, device,
                                    "line %d unknown RC=%d, please "
                                    "report to linux390@de.ibm.com",
                                    __LINE__, rc);
                        BUG();
                        break;
                }
                retries++;
        }
        dasd_schedule_bh(device);
        return rc;
}

/*
 * Start the i/o. This start_IO can fail if the channel is really busy.
 * In that case set up a timer to start the request later.
 */
int
dasd_start_IO(struct dasd_ccw_req * cqr)
{
        struct dasd_device *device;
        int rc;

        /* Check the cqr */
        rc = dasd_check_cqr(cqr);
        if (rc)
                return rc;
        device = (struct dasd_device *) cqr->device;
        if (cqr->retries < 0) {
                DEV_MESSAGE(KERN_DEBUG, device,
                            "start_IO: request %p (%02x/%i) - no retry left.",
                            cqr, cqr->status, cqr->retries);
                cqr->status = DASD_CQR_FAILED;
                return -EIO;
        }
        cqr->startclk = get_clock();
        cqr->starttime = jiffies;
        cqr->retries--;
        rc = ccw_device_start(device->cdev, cqr->cpaddr, (long) cqr,
                              cqr->lpm, 0);
        switch (rc) {
        case 0:
                cqr->status = DASD_CQR_IN_IO;
                DBF_DEV_EVENT(DBF_DEBUG, device,
                              "start_IO: request %p started successful",
                              cqr);
                break;
        case -EBUSY:
                DBF_DEV_EVENT(DBF_ERR, device, "%s",
                              "start_IO: device busy, retry later");
                break;
        case -ETIMEDOUT:
                DBF_DEV_EVENT(DBF_ERR, device, "%s",
                              "start_IO: request timeout, retry later");
                break;
        case -EACCES:
                /* -EACCES indicates that the request used only a
                 * subset of the available pathes and all these
                 * pathes are gone.
                 * Do a retry with all available pathes.
                 */
                cqr->lpm = LPM_ANYPATH;
                DBF_DEV_EVENT(DBF_ERR, device, "%s",
                              "start_IO: selected pathes gone,"
                              " retry on all pathes");
                break;
        case -ENODEV:
        case -EIO:
                DBF_DEV_EVENT(DBF_ERR, device, "%s",
                              "start_IO: device gone, retry");
                break;
        default:
                DEV_MESSAGE(KERN_ERR, device,
                            "line %d unknown RC=%d, please report"
                            " to linux390@de.ibm.com", __LINE__, rc);
                BUG();
                break;
        }
        return rc;
}

/*
 * Timeout function for dasd devices. This is used for different purposes
 *  1) missing interrupt handler for normal operation
 *  2) delayed start of request where start_IO failed with -EBUSY
 *  3) timeout for missing state change interrupts
 * The head of the ccw queue will have status DASD_CQR_IN_IO for 1),
 * DASD_CQR_QUEUED for 2) and 3).
 */
static void
dasd_timeout_device(unsigned long ptr)
{
        unsigned long flags;
        struct dasd_device *device;

        device = (struct dasd_device *) ptr;
        spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
        /* re-activate request queue */
        device->stopped &= ~DASD_STOPPED_PENDING;
        spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
        dasd_schedule_bh(device);
}

/*
 * Setup timeout for a device in jiffies.
 */
void
dasd_set_timer(struct dasd_device *device, int expires)
{
        if (expires == 0) {
                if (timer_pending(&device->timer))
                        del_timer(&device->timer);
                return;
        }
        if (timer_pending(&device->timer)) {
                if (mod_timer(&device->timer, jiffies + expires))
                        return;
        }
        device->timer.function = dasd_timeout_device;
        device->timer.data = (unsigned long) device;
        device->timer.expires = jiffies + expires;
        add_timer(&device->timer);
}

/*
 * Clear timeout for a device.
 */
void
dasd_clear_timer(struct dasd_device *device)
{
        if (timer_pending(&device->timer))
                del_timer(&device->timer);
}

static void
dasd_handle_killed_request(struct ccw_device *cdev, unsigned long intparm)
{
        struct dasd_ccw_req *cqr;
        struct dasd_device *device;

        cqr = (struct dasd_ccw_req *) intparm;
        if (cqr->status != DASD_CQR_IN_IO) {
                MESSAGE(KERN_DEBUG,
                        "invalid status in handle_killed_request: "
                        "bus_id %s, status %02x",
                        cdev->dev.bus_id, cqr->status);
                return;
        }

        device = (struct dasd_device *) cqr->device;
        if (device == NULL ||
            device != dasd_device_from_cdev_locked(cdev) ||
            strncmp(device->discipline->ebcname, (char *) &cqr->magic, 4)) {
                MESSAGE(KERN_DEBUG, "invalid device in request: bus_id %s",
                        cdev->dev.bus_id);
                return;
        }

        /* Schedule request to be retried. */
        cqr->status = DASD_CQR_QUEUED;

        dasd_clear_timer(device);
        dasd_schedule_bh(device);
        dasd_put_device(device);
}

static void
dasd_handle_state_change_pending(struct dasd_device *device)
{
        struct dasd_ccw_req *cqr;
        struct list_head *l, *n;

        /* First of all start sense subsystem status request. */
        dasd_eer_snss(device);

        device->stopped &= ~DASD_STOPPED_PENDING;

        /* restart all 'running' IO on queue */
        list_for_each_safe(l, n, &device->ccw_queue) {
                cqr = list_entry(l, struct dasd_ccw_req, list);
                if (cqr->status == DASD_CQR_IN_IO) {
                        cqr->status = DASD_CQR_QUEUED;
                }
        }
        dasd_clear_timer(device);
        dasd_schedule_bh(device);
}

/*
 * Interrupt handler for "normal" ssch-io based dasd devices.
 */
void
dasd_int_handler(struct ccw_device *cdev, unsigned long intparm,
                 struct irb *irb)
{
        struct dasd_ccw_req *cqr, *next;
        struct dasd_device *device;
        unsigned long long now;
        int expires;
        dasd_era_t era;
        char mask;

        if (IS_ERR(irb)) {
                switch (PTR_ERR(irb)) {
                case -EIO:
                        dasd_handle_killed_request(cdev, intparm);
                        break;
                case -ETIMEDOUT:
                        printk(KERN_WARNING"%s(%s): request timed out\n",
                               __FUNCTION__, cdev->dev.bus_id);
                        //FIXME - dasd uses own timeout interface...
                        break;
                default:
                        printk(KERN_WARNING"%s(%s): unknown error %ld\n",
                               __FUNCTION__, cdev->dev.bus_id, PTR_ERR(irb));
                }
                return;
        }

        now = get_clock();

        DBF_EVENT(DBF_ERR, "Interrupt: bus_id %s CS/DS %04x ip %08x",
                  cdev->dev.bus_id, ((irb->scsw.cstat<<8)|irb->scsw.dstat),
                  (unsigned int) intparm);

        /* first of all check for state change pending interrupt */
        mask = DEV_STAT_ATTENTION | DEV_STAT_DEV_END | DEV_STAT_UNIT_EXCEP;
        if ((irb->scsw.dstat & mask) == mask) {
                device = dasd_device_from_cdev_locked(cdev);
                if (!IS_ERR(device)) {
                        dasd_handle_state_change_pending(device);
                        dasd_put_device(device);
                }
                return;
        }

        cqr = (struct dasd_ccw_req *) intparm;

        /* check for unsolicited interrupts */
        if (cqr == NULL) {
                MESSAGE(KERN_DEBUG,
                        "unsolicited interrupt received: bus_id %s",
                        cdev->dev.bus_id);
                return;
        }

        device = (struct dasd_device *) cqr->device;
        if (device == NULL ||
            strncmp(device->discipline->ebcname, (char *) &cqr->magic, 4)) {
                MESSAGE(KERN_DEBUG, "invalid device in request: bus_id %s",
                        cdev->dev.bus_id);
                return;
        }

        /* Check for clear pending */
        if (cqr->status == DASD_CQR_CLEAR &&
            irb->scsw.fctl & SCSW_FCTL_CLEAR_FUNC) {
                cqr->status = DASD_CQR_QUEUED;
                dasd_clear_timer(device);
                wake_up(&dasd_flush_wq);
                dasd_schedule_bh(device);
                return;
        }

        /* check status - the request might have been killed by dyn detach */
        if (cqr->status != DASD_CQR_IN_IO) {
                MESSAGE(KERN_DEBUG,
                        "invalid status: bus_id %s, status %02x",
                        cdev->dev.bus_id, cqr->status);
                return;
        }
        DBF_DEV_EVENT(DBF_DEBUG, device, "Int: CS/DS 0x%04x for cqr %p",
                      ((irb->scsw.cstat << 8) | irb->scsw.dstat), cqr);

        /* Find out the appropriate era_action. */
        if (irb->scsw.fctl & SCSW_FCTL_HALT_FUNC)
                era = dasd_era_fatal;
        else if (irb->scsw.dstat == (DEV_STAT_CHN_END | DEV_STAT_DEV_END) &&
                 irb->scsw.cstat == 0 &&
                 !irb->esw.esw0.erw.cons)
                era = dasd_era_none;
        else if (irb->esw.esw0.erw.cons)
                era = device->discipline->examine_error(cqr, irb);
        else
                era = dasd_era_recover;

        DBF_DEV_EVENT(DBF_DEBUG, device, "era_code %d", era);
        expires = 0;
        if (era == dasd_era_none) {
                cqr->status = DASD_CQR_DONE;
                cqr->stopclk = now;
                /* Start first request on queue if possible -> fast_io. */
                if (cqr->list.next != &device->ccw_queue) {
                        next = list_entry(cqr->list.next,
                                          struct dasd_ccw_req, list);
                        if ((next->status == DASD_CQR_QUEUED) &&
                            (!device->stopped)) {
                                if (device->discipline->start_IO(next) == 0)
                                        expires = next->expires;
                                else
                                        DEV_MESSAGE(KERN_DEBUG, device, "%s",
                                                    "Interrupt fastpath "
                                                    "failed!");
                        }
                }
        } else {                /* error */
                memcpy(&cqr->irb, irb, sizeof (struct irb));
                if (device->features & DASD_FEATURE_ERPLOG) {
                        /* dump sense data */
                        dasd_log_sense(cqr, irb);
                }
                switch (era) {
                case dasd_era_fatal:
                        cqr->status = DASD_CQR_FAILED;
                        cqr->stopclk = now;
                        break;
                case dasd_era_recover:
                        cqr->status = DASD_CQR_ERROR;
                        break;
                default:
                        BUG();
                }
        }
        if (expires != 0)
                dasd_set_timer(device, expires);
        else
                dasd_clear_timer(device);
        dasd_schedule_bh(device);
}

/*
 * posts the buffer_cache about a finalized request
 */
static inline void
dasd_end_request(struct request *req, int uptodate)
{
        if (end_that_request_first(req, uptodate, req->hard_nr_sectors))
                BUG();
        add_disk_randomness(req->rq_disk);
        end_that_request_last(req, uptodate);
}

/*
 * Process finished error recovery ccw.
 */
static inline void
__dasd_process_erp(struct dasd_device *device, struct dasd_ccw_req *cqr)
{
        dasd_erp_fn_t erp_fn;

        if (cqr->status == DASD_CQR_DONE)
                DBF_DEV_EVENT(DBF_NOTICE, device, "%s", "ERP successful");
        else
                DEV_MESSAGE(KERN_ERR, device, "%s", "ERP unsuccessful");
        erp_fn = device->discipline->erp_postaction(cqr);
        erp_fn(cqr);
}

/*
 * Process ccw request queue.
 */
static void
__dasd_process_ccw_queue(struct dasd_device * device,
                         struct list_head *final_queue)
{
        struct list_head *l, *n;
        struct dasd_ccw_req *cqr;
        dasd_erp_fn_t erp_fn;

restart:
        /* Process request with final status. */
        list_for_each_safe(l, n, &device->ccw_queue) {
                cqr = list_entry(l, struct dasd_ccw_req, list);
                /* Stop list processing at the first non-final request. */
                if (cqr->status != DASD_CQR_DONE &&
                    cqr->status != DASD_CQR_FAILED &&
                    cqr->status != DASD_CQR_ERROR)
                        break;
                /*  Process requests with DASD_CQR_ERROR */
                if (cqr->status == DASD_CQR_ERROR) {
                        if (cqr->irb.scsw.fctl & SCSW_FCTL_HALT_FUNC) {
                                cqr->status = DASD_CQR_FAILED;
                                cqr->stopclk = get_clock();
                        } else {
                                if (cqr->irb.esw.esw0.erw.cons &&
                                    test_bit(DASD_CQR_FLAGS_USE_ERP,
                                             &cqr->flags)) {
                                        erp_fn = device->discipline->
                                                erp_action(cqr);
                                        erp_fn(cqr);
                                } else
                                        dasd_default_erp_action(cqr);
                        }
                        goto restart;
                }

                /* First of all call extended error reporting. */
                if (dasd_eer_enabled(device) &&
                    cqr->status == DASD_CQR_FAILED) {
                        dasd_eer_write(device, cqr, DASD_EER_FATALERROR);

                        /* restart request  */
                        cqr->status = DASD_CQR_QUEUED;
                        cqr->retries = 255;
                        device->stopped |= DASD_STOPPED_QUIESCE;
                        goto restart;
                }

                /* Process finished ERP request. */
                if (cqr->refers) {
                        __dasd_process_erp(device, cqr);
                        goto restart;
                }

                /* Rechain finished requests to final queue */
                cqr->endclk = get_clock();
                list_move_tail(&cqr->list, final_queue);
        }
}

static void
dasd_end_request_cb(struct dasd_ccw_req * cqr, void *data)
{
        struct request *req;
        struct dasd_device *device;
        int status;

        req = (struct request *) data;
        device = cqr->device;
        dasd_profile_end(device, cqr, req);
        status = cqr->device->discipline->free_cp(cqr,req);
        spin_lock_irq(&device->request_queue_lock);
        dasd_end_request(req, status);
        spin_unlock_irq(&device->request_queue_lock);
}


/*
 * Fetch requests from the block device queue.
 */
static void
__dasd_process_blk_queue(struct dasd_device * device)
{
        struct request_queue *queue;
        struct request *req;
        struct dasd_ccw_req *cqr;
        int nr_queued;

        queue = device->request_queue;
        /* No queue ? Then there is nothing to do. */
        if (queue == NULL)
                return;

        /*
         * We requeue request from the block device queue to the ccw
         * queue only in two states. In state DASD_STATE_READY the
         * partition detection is done and we need to requeue requests
         * for that. State DASD_STATE_ONLINE is normal block device
         * operation.
         */
        if (device->state != DASD_STATE_READY &&
            device->state != DASD_STATE_ONLINE)
                return;
        nr_queued = 0;
        /* Now we try to fetch requests from the request queue */
        list_for_each_entry(cqr, &device->ccw_queue, list)
                if (cqr->status == DASD_CQR_QUEUED)
                        nr_queued++;
        while (!blk_queue_plugged(queue) &&
               elv_next_request(queue) &&
                nr_queued < DASD_CHANQ_MAX_SIZE) {
                req = elv_next_request(queue);

                if (device->features & DASD_FEATURE_READONLY &&
                    rq_data_dir(req) == WRITE) {
                        DBF_DEV_EVENT(DBF_ERR, device,
                                      "Rejecting write request %p",
                                      req);
                        blkdev_dequeue_request(req);
                        dasd_end_request(req, 0);
                        continue;
                }
                if (device->stopped & DASD_STOPPED_DC_EIO) {
                        blkdev_dequeue_request(req);
                        dasd_end_request(req, 0);
                        continue;
                }
                cqr = device->discipline->build_cp(device, req);
                if (IS_ERR(cqr)) {
                        if (PTR_ERR(cqr) == -ENOMEM)
                                break;  /* terminate request queue loop */
                        if (PTR_ERR(cqr) == -EAGAIN) {
                                /*
                                 * The current request cannot be build right
                                 * now, we have to try later. If this request
                                 * is the head-of-queue we stop the device
                                 * for 1/2 second.
                                 */
                                if (!list_empty(&device->ccw_queue))
                                        break;
                                device->stopped |= DASD_STOPPED_PENDING;
                                dasd_set_timer(device, HZ/2);
                                break;
                        }
                        DBF_DEV_EVENT(DBF_ERR, device,
                                      "CCW creation failed (rc=%ld) "
                                      "on request %p",
                                      PTR_ERR(cqr), req);
                        blkdev_dequeue_request(req);
                        dasd_end_request(req, 0);
                        continue;
                }
                cqr->callback = dasd_end_request_cb;
                cqr->callback_data = (void *) req;
                cqr->status = DASD_CQR_QUEUED;
                blkdev_dequeue_request(req);
                list_add_tail(&cqr->list, &device->ccw_queue);
                dasd_profile_start(device, cqr, req);
                nr_queued++;
        }
}

/*
 * Take a look at the first request on the ccw queue and check
 * if it reached its expire time. If so, terminate the IO.
 */
static void
__dasd_check_expire(struct dasd_device * device)
{
        struct dasd_ccw_req *cqr;

        if (list_empty(&device->ccw_queue))
                return;
        cqr = list_entry(device->ccw_queue.next, struct dasd_ccw_req, list);
        if ((cqr->status == DASD_CQR_IN_IO && cqr->expires != 0) &&
            (time_after_eq(jiffies, cqr->expires + cqr->starttime))) {
                if (device->discipline->term_IO(cqr) != 0) {
                        /* Hmpf, try again in 5 sec */
                        dasd_set_timer(device, 5*HZ);
                        DEV_MESSAGE(KERN_ERR, device,
                                    "internal error - timeout (%is) expired "
                                    "for cqr %p, termination failed, "
                                    "retrying in 5s",
                                    (cqr->expires/HZ), cqr);
                } else {
                        DEV_MESSAGE(KERN_ERR, device,
                                    "internal error - timeout (%is) expired "
                                    "for cqr %p (%i retries left)",
                                    (cqr->expires/HZ), cqr, cqr->retries);
                }
        }
}

/*
 * Take a look at the first request on the ccw queue and check
 * if it needs to be started.
 */
static void
__dasd_start_head(struct dasd_device * device)
{
        struct dasd_ccw_req *cqr;
        int rc;

        if (list_empty(&device->ccw_queue))
                return;
        cqr = list_entry(device->ccw_queue.next, struct dasd_ccw_req, list);
        if (cqr->status != DASD_CQR_QUEUED)
                return;
        /* Non-temporary stop condition will trigger fail fast */
        if (device->stopped & ~DASD_STOPPED_PENDING &&
            test_bit(DASD_CQR_FLAGS_FAILFAST, &cqr->flags) &&
            (!dasd_eer_enabled(device))) {
                cqr->status = DASD_CQR_FAILED;
                dasd_schedule_bh(device);
                return;
        }
        /* Don't try to start requests if device is stopped */
        if (device->stopped)
                return;

        rc = device->discipline->start_IO(cqr);
        if (rc == 0)
                dasd_set_timer(device, cqr->expires);
        else if (rc == -EACCES) {
                dasd_schedule_bh(device);
        } else
                /* Hmpf, try again in 1/2 sec */
                dasd_set_timer(device, 50);
}

static inline int
_wait_for_clear(struct dasd_ccw_req *cqr)
{
        return (cqr->status == DASD_CQR_QUEUED);
}

/*
 * Remove all requests from the ccw queue (all = '1') or only block device
 * requests in case all = '0'.
 * Take care of the erp-chain (chained via cqr->refers) and remove either
 * the whole erp-chain or none of the erp-requests.
 * If a request is currently running, term_IO is called and the request
 * is re-queued. Prior to removing the terminated request we need to wait
 * for the clear-interrupt.
 * In case termination is not possible we stop processing and just finishing
 * the already moved requests.
 */
static int
dasd_flush_ccw_queue(struct dasd_device * device, int all)
{
        struct dasd_ccw_req *cqr, *orig, *n;
        int rc, i;

        struct list_head flush_queue;

        INIT_LIST_HEAD(&flush_queue);
        spin_lock_irq(get_ccwdev_lock(device->cdev));
        rc = 0;
restart:
        list_for_each_entry_safe(cqr, n, &device->ccw_queue, list) {
                /* get original request of erp request-chain */
                for (orig = cqr; orig->refers != NULL; orig = orig->refers);

                /* Flush all request or only block device requests? */
                if (all == 0 && cqr->callback != dasd_end_request_cb &&
                    orig->callback != dasd_end_request_cb) {
                        continue;
                }
                /* Check status and move request to flush_queue */
                switch (cqr->status) {
                case DASD_CQR_IN_IO:
                        rc = device->discipline->term_IO(cqr);
                        if (rc) {
                                /* unable to terminate requeust */
                                DEV_MESSAGE(KERN_ERR, device,
                                            "dasd flush ccw_queue is unable "
                                            " to terminate request %p",
                                            cqr);
                                /* stop flush processing */
                                goto finished;
                        }
                        break;
                case DASD_CQR_QUEUED:
                case DASD_CQR_ERROR:
                        /* set request to FAILED */
                        cqr->stopclk = get_clock();
                        cqr->status = DASD_CQR_FAILED;
                        break;
                default: /* do not touch the others */
                        break;
                }
                /* Rechain request (including erp chain) */
                for (i = 0; cqr != NULL; cqr = cqr->refers, i++) {
                        cqr->endclk = get_clock();
                        list_move_tail(&cqr->list, &flush_queue);
                }
                if (i > 1)
                        /* moved more than one request - need to restart */
                        goto restart;
        }

finished:
        spin_unlock_irq(get_ccwdev_lock(device->cdev));
        /* Now call the callback function of flushed requests */
restart_cb:
        list_for_each_entry_safe(cqr, n, &flush_queue, list) {
                if (cqr->status == DASD_CQR_CLEAR) {
                        /* wait for clear interrupt! */
                        wait_event(dasd_flush_wq, _wait_for_clear(cqr));
                        cqr->status = DASD_CQR_FAILED;
                }
                /* Process finished ERP request. */
                if (cqr->refers) {
                        __dasd_process_erp(device, cqr);
                        /* restart list_for_xx loop since dasd_process_erp
                         * might remove multiple elements */
                        goto restart_cb;
                }
                /* call the callback function */
                cqr->endclk = get_clock();
                if (cqr->callback != NULL)
                        (cqr->callback)(cqr, cqr->callback_data);
        }
        return rc;
}

/*
 * Acquire the device lock and process queues for the device.
 */
static void
dasd_tasklet(struct dasd_device * device)
{
        struct list_head final_queue;
        struct list_head *l, *n;
        struct dasd_ccw_req *cqr;

        atomic_set (&device->tasklet_scheduled, 0);
        INIT_LIST_HEAD(&final_queue);
        spin_lock_irq(get_ccwdev_lock(device->cdev));
        /* Check expire time of first request on the ccw queue. */
        __dasd_check_expire(device);
        /* Finish off requests on ccw queue */
        __dasd_process_ccw_queue(device, &final_queue);
        spin_unlock_irq(get_ccwdev_lock(device->cdev));
        /* Now call the callback function of requests with final status */
        list_for_each_safe(l, n, &final_queue) {
                cqr = list_entry(l, struct dasd_ccw_req, list);
                list_del_init(&cqr->list);
                if (cqr->callback != NULL)
                        (cqr->callback)(cqr, cqr->callback_data);
        }
        spin_lock_irq(&device->request_queue_lock);
        spin_lock(get_ccwdev_lock(device->cdev));
        /* Get new request from the block device request queue */
        __dasd_process_blk_queue(device);
        /* Now check if the head of the ccw queue needs to be started. */
        __dasd_start_head(device);
        spin_unlock(get_ccwdev_lock(device->cdev));
        spin_unlock_irq(&device->request_queue_lock);
        dasd_put_device(device);
}

/*
 * Schedules a call to dasd_tasklet over the device tasklet.
 */
void
dasd_schedule_bh(struct dasd_device * device)
{
        /* Protect against rescheduling. */
        if (atomic_cmpxchg (&device->tasklet_scheduled, 0, 1) != 0)
                return;
        dasd_get_device(device);
        tasklet_hi_schedule(&device->tasklet);
}

/*
 * Queue a request to the head of the ccw_queue. Start the I/O if
 * possible.
 */
void
dasd_add_request_head(struct dasd_ccw_req *req)
{
        struct dasd_device *device;
        unsigned long flags;

        device = req->device;
        spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
        req->status = DASD_CQR_QUEUED;
        req->device = device;
        list_add(&req->list, &device->ccw_queue);
        /* let the bh start the request to keep them in order */
        dasd_schedule_bh(device);
        spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
}

/*
 * Queue a request to the tail of the ccw_queue. Start the I/O if
 * possible.
 */
void
dasd_add_request_tail(struct dasd_ccw_req *req)
{
        struct dasd_device *device;
        unsigned long flags;

        device = req->device;
        spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
        req->status = DASD_CQR_QUEUED;
        req->device = device;
        list_add_tail(&req->list, &device->ccw_queue);
        /* let the bh start the request to keep them in order */
        dasd_schedule_bh(device);
        spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
}

/*
 * Wakeup callback.
 */
static void
dasd_wakeup_cb(struct dasd_ccw_req *cqr, void *data)
{
        wake_up((wait_queue_head_t *) data);
}

static inline int
_wait_for_wakeup(struct dasd_ccw_req *cqr)
{
        struct dasd_device *device;
        int rc;

        device = cqr->device;
        spin_lock_irq(get_ccwdev_lock(device->cdev));
        rc = ((cqr->status == DASD_CQR_DONE ||
               cqr->status == DASD_CQR_FAILED) &&
              list_empty(&cqr->list));
        spin_unlock_irq(get_ccwdev_lock(device->cdev));
        return rc;
}

/*
 * Attempts to start a special ccw queue and waits for its completion.
 */
int
dasd_sleep_on(struct dasd_ccw_req * cqr)
{
        wait_queue_head_t wait_q;
        struct dasd_device *device;
        int rc;

        device = cqr->device;
        spin_lock_irq(get_ccwdev_lock(device->cdev));

        init_waitqueue_head (&wait_q);
        cqr->callback = dasd_wakeup_cb;
        cqr->callback_data = (void *) &wait_q;
        cqr->status = DASD_CQR_QUEUED;
        list_add_tail(&cqr->list, &device->ccw_queue);

        /* let the bh start the request to keep them in order */
        dasd_schedule_bh(device);

        spin_unlock_irq(get_ccwdev_lock(device->cdev));

        wait_event(wait_q, _wait_for_wakeup(cqr));

        /* Request status is either done or failed. */
        rc = (cqr->status == DASD_CQR_FAILED) ? -EIO : 0;
        return rc;
}

/*
 * Attempts to start a special ccw queue and wait interruptible
 * for its completion.
 */
int
dasd_sleep_on_interruptible(struct dasd_ccw_req * cqr)
{
        wait_queue_head_t wait_q;
        struct dasd_device *device;
        int rc, finished;

        device = cqr->device;
        spin_lock_irq(get_ccwdev_lock(device->cdev));

        init_waitqueue_head (&wait_q);
        cqr->callback = dasd_wakeup_cb;
        cqr->callback_data = (void *) &wait_q;
        cqr->status = DASD_CQR_QUEUED;
        list_add_tail(&cqr->list, &device->ccw_queue);

        /* let the bh start the request to keep them in order */
        dasd_schedule_bh(device);
        spin_unlock_irq(get_ccwdev_lock(device->cdev));

        finished = 0;
        while (!finished) {
                rc = wait_event_interruptible(wait_q, _wait_for_wakeup(cqr));
                if (rc != -ERESTARTSYS) {
                        /* Request is final (done or failed) */
                        rc = (cqr->status == DASD_CQR_DONE) ? 0 : -EIO;
                        break;
                }
                spin_lock_irq(get_ccwdev_lock(device->cdev));
                switch (cqr->status) {
                case DASD_CQR_IN_IO:
                        /* terminate runnig cqr */
                        if (device->discipline->term_IO) {
                                cqr->retries = -1;
                                device->discipline->term_IO(cqr);
                                /* wait (non-interruptible) for final status
                                 * because signal ist still pending */
                                spin_unlock_irq(get_ccwdev_lock(device->cdev));
                                wait_event(wait_q, _wait_for_wakeup(cqr));
                                spin_lock_irq(get_ccwdev_lock(device->cdev));
                                rc = (cqr->status == DASD_CQR_DONE) ? 0 : -EIO;
                                finished = 1;
                        }
                        break;
                case DASD_CQR_QUEUED:
                        /* request  */
                        list_del_init(&cqr->list);
                        rc = -EIO;
                        finished = 1;
                        break;
                default:
                        /* cqr with 'non-interruptable' status - just wait */
                        break;
                }
                spin_unlock_irq(get_ccwdev_lock(device->cdev));
        }
        return rc;
}

/*
 * Whoa nelly now it gets really hairy. For some functions (e.g. steal lock
 * for eckd devices) the currently running request has to be terminated
 * and be put back to status queued, before the special request is added
 * to the head of the queue. Then the special request is waited on normally.
 */
static inline int
_dasd_term_running_cqr(struct dasd_device *device)
{
        struct dasd_ccw_req *cqr;

        if (list_empty(&device->ccw_queue))
                return 0;
        cqr = list_entry(device->ccw_queue.next, struct dasd_ccw_req, list);
        return device->discipline->term_IO(cqr);
}

int
dasd_sleep_on_immediatly(struct dasd_ccw_req * cqr)
{
        wait_queue_head_t wait_q;
        struct dasd_device *device;
        int rc;

        device = cqr->device;
        spin_lock_irq(get_ccwdev_lock(device->cdev));
        rc = _dasd_term_running_cqr(device);
        if (rc) {
                spin_unlock_irq(get_ccwdev_lock(device->cdev));
                return rc;
        }

        init_waitqueue_head (&wait_q);
        cqr->callback = dasd_wakeup_cb;
        cqr->callback_data = (void *) &wait_q;
        cqr->status = DASD_CQR_QUEUED;
        list_add(&cqr->list, &device->ccw_queue);

        /* let the bh start the request to keep them in order */
        dasd_schedule_bh(device);

        spin_unlock_irq(get_ccwdev_lock(device->cdev));

        wait_event(wait_q, _wait_for_wakeup(cqr));

        /* Request status is either done or failed. */
        rc = (cqr->status == DASD_CQR_FAILED) ? -EIO : 0;
        return rc;
}

/*
 * Cancels a request that was started with dasd_sleep_on_req.
 * This is useful to timeout requests. The request will be
 * terminated if it is currently in i/o.
 * Returns 1 if the request has been terminated.
 */
int
dasd_cancel_req(struct dasd_ccw_req *cqr)
{
        struct dasd_device *device = cqr->device;
        unsigned long flags;
        int rc;

        rc = 0;
        spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
        switch (cqr->status) {
        case DASD_CQR_QUEUED:
                /* request was not started - just set to failed */
                cqr->status = DASD_CQR_FAILED;
                break;
        case DASD_CQR_IN_IO:
                /* request in IO - terminate IO and release again */
                if (device->discipline->term_IO(cqr) != 0)
                        /* what to do if unable to terminate ??????
                           e.g. not _IN_IO */
                        cqr->status = DASD_CQR_FAILED;
                cqr->stopclk = get_clock();
                rc = 1;
                break;
        case DASD_CQR_DONE:
        case DASD_CQR_FAILED:
                /* already finished - do nothing */
                break;
        default:
                DEV_MESSAGE(KERN_ALERT, device,
                            "invalid status %02x in request",
                            cqr->status);
                BUG();

        }
        spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
        dasd_schedule_bh(device);
        return rc;
}

/*
 * SECTION: Block device operations (request queue, partitions, open, release).
 */

/*
 * Dasd request queue function. Called from ll_rw_blk.c
 */
static void
do_dasd_request(struct request_queue * queue)
{
        struct dasd_device *device;

        device = (struct dasd_device *) queue->queuedata;
        spin_lock(get_ccwdev_lock(device->cdev));
        /* Get new request from the block device request queue */
        __dasd_process_blk_queue(device);
        /* Now check if the head of the ccw queue needs to be started. */
        __dasd_start_head(device);
        spin_unlock(get_ccwdev_lock(device->cdev));
}

/*
 * Allocate and initialize request queue and default I/O scheduler.
 */
static int
dasd_alloc_queue(struct dasd_device * device)
{
        int rc;

        device->request_queue = blk_init_queue(do_dasd_request,
                                               &device->request_queue_lock);
        if (device->request_queue == NULL)
                return -ENOMEM;

        device->request_queue->queuedata = device;

        elevator_exit(device->request_queue->elevator);
        rc = elevator_init(device->request_queue, "deadline");
        if (rc) {
                blk_cleanup_queue(device->request_queue);
                return rc;
        }
        return 0;
}

/*
 * Allocate and initialize request queue.
 */
static void
dasd_setup_queue(struct dasd_device * device)
{
        int max;

        blk_queue_hardsect_size(device->request_queue, device->bp_block);
        max = device->discipline->max_blocks << device->s2b_shift;
        blk_queue_max_sectors(device->request_queue, max);
        blk_queue_max_phys_segments(device->request_queue, -1L);
        blk_queue_max_hw_segments(device->request_queue, -1L);
        blk_queue_max_segment_size(device->request_queue, -1L);
        blk_queue_segment_boundary(device->request_queue, -1L);
        blk_queue_ordered(device->request_queue, QUEUE_ORDERED_TAG, NULL);
}

/*
 * Deactivate and free request queue.
 */
static void
dasd_free_queue(struct dasd_device * device)
{
        if (device->request_queue) {
                blk_cleanup_queue(device->request_queue);
                device->request_queue = NULL;
        }
}

/*
 * Flush request on the request queue.
 */
static void
dasd_flush_request_queue(struct dasd_device * device)
{
        struct request *req;

        if (!device->request_queue)
                return;

        spin_lock_irq(&device->request_queue_lock);
        while ((req = elv_next_request(device->request_queue))) {
                blkdev_dequeue_request(req);
                dasd_end_request(req, 0);
        }
        spin_unlock_irq(&device->request_queue_lock);
}

static int
dasd_open(struct inode *inp, struct file *filp)
{
        struct gendisk *disk = inp->i_bdev->bd_disk;
        struct dasd_device *device = disk->private_data;
        int rc;

        atomic_inc(&device->open_count);
        if (test_bit(DASD_FLAG_OFFLINE, &device->flags)) {
                rc = -ENODEV;
                goto unlock;
        }

        if (!try_module_get(device->discipline->owner)) {
                rc = -EINVAL;
                goto unlock;
        }

        if (dasd_probeonly) {
                DEV_MESSAGE(KERN_INFO, device, "%s",
                            "No access to device due to probeonly mode");
                rc = -EPERM;
                goto out;
        }

        if (device->state <= DASD_STATE_BASIC) {
                DBF_DEV_EVENT(DBF_ERR, device, " %s",
                              " Cannot open unrecognized device");
                rc = -ENODEV;
                goto out;
        }

        return 0;

out:
        module_put(device->discipline->owner);
unlock:
        atomic_dec(&device->open_count);
        return rc;
}

static int
dasd_release(struct inode *inp, struct file *filp)
{
        struct gendisk *disk = inp->i_bdev->bd_disk;
        struct dasd_device *device = disk->private_data;

        atomic_dec(&device->open_count);
        module_put(device->discipline->owner);
        return 0;
}

/*
 * Return disk geometry.
 */
static int
dasd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
{
        struct dasd_device *device;

        device = bdev->bd_disk->private_data;
        if (!device)
                return -ENODEV;

        if (!device->discipline ||
            !device->discipline->fill_geometry)
                return -EINVAL;

        device->discipline->fill_geometry(device, geo);
        geo->start = get_start_sect(bdev) >> device->s2b_shift;
        return 0;
}

struct block_device_operations
dasd_device_operations = {
        .owner          = THIS_MODULE,
        .open           = dasd_open,
        .release        = dasd_release,
        .ioctl          = dasd_ioctl,
        .compat_ioctl   = dasd_compat_ioctl,
        .getgeo         = dasd_getgeo,
};


static void
dasd_exit(void)
{
#ifdef CONFIG_PROC_FS
        dasd_proc_exit();
#endif
        dasd_eer_exit();
        if (dasd_page_cache != NULL) {
                kmem_cache_destroy(dasd_page_cache);
                dasd_page_cache = NULL;
        }
        dasd_gendisk_exit();
        dasd_devmap_exit();
        if (dasd_debug_area != NULL) {
                debug_unregister(dasd_debug_area);
                dasd_debug_area = NULL;
        }
}

/*
 * SECTION: common functions for ccw_driver use
 */

/*
 * Initial attempt at a probe function. this can be simplified once
 * the other detection code is gone.
 */
int
dasd_generic_probe (struct ccw_device *cdev,
                    struct dasd_discipline *discipline)
{
        int ret;

        ret = ccw_device_set_options(cdev, CCWDEV_DO_PATHGROUP);
        if (ret) {
                printk(KERN_WARNING
                       "dasd_generic_probe: could not set ccw-device options "
                       "for %s\n", cdev->dev.bus_id);
                return ret;
        }
        ret = dasd_add_sysfs_files(cdev);
        if (ret) {
                printk(KERN_WARNING
                       "dasd_generic_probe: could not add sysfs entries "
                       "for %s\n", cdev->dev.bus_id);
                return ret;
        }
        cdev->handler = &dasd_int_handler;

        /*
         * Automatically online either all dasd devices (dasd_autodetect)
         * or all devices specified with dasd= parameters during
         * initial probe.
         */
        if ((dasd_get_feature(cdev, DASD_FEATURE_INITIAL_ONLINE) > 0 ) ||
            (dasd_autodetect && dasd_busid_known(cdev->dev.bus_id) != 0))
                ret = ccw_device_set_online(cdev);
        if (ret)
                printk(KERN_WARNING
                       "dasd_generic_probe: could not initially online "
                       "ccw-device %s\n", cdev->dev.bus_id);
        return ret;
}

/*
 * This will one day be called from a global not_oper handler.
 * It is also used by driver_unregister during module unload.
 */
void
dasd_generic_remove (struct ccw_device *cdev)
{
        struct dasd_device *device;

        cdev->handler = NULL;

        dasd_remove_sysfs_files(cdev);
        device = dasd_device_from_cdev(cdev);
        if (IS_ERR(device))
                return;
        if (test_and_set_bit(DASD_FLAG_OFFLINE, &device->flags)) {
                /* Already doing offline processing */
                dasd_put_device(device);
                return;
        }
        /*
         * This device is removed unconditionally. Set offline
         * flag to prevent dasd_open from opening it while it is
         * no quite down yet.

         */
        dasd_set_target_state(device, DASD_STATE_NEW);
        /* dasd_delete_device destroys the device reference. */
        dasd_delete_device(device);
}

/*
 * Activate a device. This is called from dasd_{eckd,fba}_probe() when either
 * the device is detected for the first time and is supposed to be used
 * or the user has started activation through sysfs.
 */
int
dasd_generic_set_online (struct ccw_device *cdev,
                         struct dasd_discipline *base_discipline)

{
        struct dasd_discipline *discipline;
        struct dasd_device *device;
        int rc;

        /* first online clears initial online feature flag */
        dasd_set_feature(cdev, DASD_FEATURE_INITIAL_ONLINE, 0);
        device = dasd_create_device(cdev);
        if (IS_ERR(device))
                return PTR_ERR(device);

        discipline = base_discipline;
        if (device->features & DASD_FEATURE_USEDIAG) {
                if (!dasd_diag_discipline_pointer) {
                        printk (KERN_WARNING
                                "dasd_generic couldn't online device %s "
                                "- discipline DIAG not available\n",
                                cdev->dev.bus_id);
                        dasd_delete_device(device);
                        return -ENODEV;
                }
                discipline = dasd_diag_discipline_pointer;
        }
        if (!try_module_get(base_discipline->owner)) {
                dasd_delete_device(device);
                return -EINVAL;
        }
        if (!try_module_get(discipline->owner)) {
                module_put(base_discipline->owner);
                dasd_delete_device(device);
                return -EINVAL;
        }
        device->base_discipline = base_discipline;
        device->discipline = discipline;

        rc = discipline->check_device(device);
        if (rc) {
                printk (KERN_WARNING
                        "dasd_generic couldn't online device %s "
                        "with discipline %s rc=%i\n",
                        cdev->dev.bus_id, discipline->name, rc);
                module_put(discipline->owner);
                module_put(base_discipline->owner);
                dasd_delete_device(device);
                return rc;
        }

        dasd_set_target_state(device, DASD_STATE_ONLINE);
        if (device->state <= DASD_STATE_KNOWN) {
                printk (KERN_WARNING
                        "dasd_generic discipline not found for %s\n",
                        cdev->dev.bus_id);
                rc = -ENODEV;
                dasd_set_target_state(device, DASD_STATE_NEW);
                dasd_delete_device(device);
        } else
                pr_debug("dasd_generic device %s found\n",
                                cdev->dev.bus_id);

        /* FIXME: we have to wait for the root device but we don't want
         * to wait for each single device but for all at once. */
        wait_event(dasd_init_waitq, _wait_for_device(device));

        dasd_put_device(device);

        return rc;
}

int
dasd_generic_set_offline (struct ccw_device *cdev)
{
        struct dasd_device *device;
        int max_count, open_count;

        device = dasd_device_from_cdev(cdev);
        if (IS_ERR(device))
                return PTR_ERR(device);
        if (test_and_set_bit(DASD_FLAG_OFFLINE, &device->flags)) {
                /* Already doing offline processing */
                dasd_put_device(device);
                return 0;
        }
        /*
         * We must make sure that this device is currently not in use.
         * The open_count is increased for every opener, that includes
         * the blkdev_get in dasd_scan_partitions. We are only interested
         * in the other openers.
         */
        max_count = device->bdev ? 0 : -1;
        open_count = (int) atomic_read(&device->open_count);
        if (open_count > max_count) {
                if (open_count > 0)
                        printk (KERN_WARNING "Can't offline dasd device with "
                                "open count = %i.\n",
                                open_count);
                else
                        printk (KERN_WARNING "%s",
                                "Can't offline dasd device due to internal "
                                "use\n");
                clear_bit(DASD_FLAG_OFFLINE, &device->flags);
                dasd_put_device(device);
                return -EBUSY;
        }
        dasd_set_target_state(device, DASD_STATE_NEW);
        /* dasd_delete_device destroys the device reference. */
        dasd_delete_device(device);

        return 0;
}

int
dasd_generic_notify(struct ccw_device *cdev, int event)
{
        struct dasd_device *device;
        struct dasd_ccw_req *cqr;
        unsigned long flags;
        int ret;

        device = dasd_device_from_cdev(cdev);
        if (IS_ERR(device))
                return 0;
        spin_lock_irqsave(get_ccwdev_lock(cdev), flags);
        ret = 0;
        switch (event) {
        case CIO_GONE:
        case CIO_NO_PATH:
                /* First of all call extended error reporting. */
                dasd_eer_write(device, NULL, DASD_EER_NOPATH);

                if (device->state < DASD_STATE_BASIC)
                        break;
                /* Device is active. We want to keep it. */
                if (test_bit(DASD_FLAG_DSC_ERROR, &device->flags)) {
                        list_for_each_entry(cqr, &device->ccw_queue, list)
                                if (cqr->status == DASD_CQR_IN_IO)
                                        cqr->status = DASD_CQR_FAILED;
                        device->stopped |= DASD_STOPPED_DC_EIO;
                } else {
                        list_for_each_entry(cqr, &device->ccw_queue, list)
                                if (cqr->status == DASD_CQR_IN_IO) {
                                        cqr->status = DASD_CQR_QUEUED;
                                        cqr->retries++;
                                }
                        device->stopped |= DASD_STOPPED_DC_WAIT;
                        dasd_set_timer(device, 0);
                }
                dasd_schedule_bh(device);
                ret = 1;
                break;
        case CIO_OPER:
                /* FIXME: add a sanity check. */
                device->stopped &= ~(DASD_STOPPED_DC_WAIT|DASD_STOPPED_DC_EIO);
                dasd_schedule_bh(device);
                ret = 1;
                break;
        }
        spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);
        dasd_put_device(device);
        return ret;
}

static struct dasd_ccw_req *dasd_generic_build_rdc(struct dasd_device *device,
                                                   void *rdc_buffer,
                                                   int rdc_buffer_size,
                                                   char *magic)
{
        struct dasd_ccw_req *cqr;
        struct ccw1 *ccw;

        cqr = dasd_smalloc_request(magic, 1 /* RDC */, rdc_buffer_size, device);

        if (IS_ERR(cqr)) {
                DEV_MESSAGE(KERN_WARNING, device, "%s",
                            "Could not allocate RDC request");
                return cqr;
        }

        ccw = cqr->cpaddr;
        ccw->cmd_code = CCW_CMD_RDC;
        ccw->cda = (__u32)(addr_t)rdc_buffer;
        ccw->count = rdc_buffer_size;

        cqr->device = device;
        cqr->expires = 10*HZ;
        clear_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
        cqr->retries = 2;
        cqr->buildclk = get_clock();
        cqr->status = DASD_CQR_FILLED;
        return cqr;
}


int dasd_generic_read_dev_chars(struct dasd_device *device, char *magic,
                                void **rdc_buffer, int rdc_buffer_size)
{
        int ret;
        struct dasd_ccw_req *cqr;

        cqr = dasd_generic_build_rdc(device, *rdc_buffer, rdc_buffer_size,
                                     magic);
        if (IS_ERR(cqr))
                return PTR_ERR(cqr);

        ret = dasd_sleep_on(cqr);
        dasd_sfree_request(cqr, cqr->device);
        return ret;
}
EXPORT_SYMBOL_GPL(dasd_generic_read_dev_chars);

static int __init
dasd_init(void)
{
        int rc;

        init_waitqueue_head(&dasd_init_waitq);
        init_waitqueue_head(&dasd_flush_wq);

        /* register 'common' DASD debug area, used for all DBF_XXX calls */
        dasd_debug_area = debug_register("dasd", 1, 2, 8 * sizeof (long));
        if (dasd_debug_area == NULL) {
                rc = -ENOMEM;
                goto failed;
        }
        debug_register_view(dasd_debug_area, &debug_sprintf_view);
        debug_set_level(dasd_debug_area, DBF_WARNING);

        DBF_EVENT(DBF_EMERG, "%s", "debug area created");

        dasd_diag_discipline_pointer = NULL;

        rc = dasd_devmap_init();
        if (rc)
                goto failed;
        rc = dasd_gendisk_init();
        if (rc)
                goto failed;
        rc = dasd_parse();
        if (rc)
                goto failed;
        rc = dasd_eer_init();
        if (rc)
                goto failed;
#ifdef CONFIG_PROC_FS
        rc = dasd_proc_init();
        if (rc)
                goto failed;
#endif

        return 0;
failed:
        MESSAGE(KERN_INFO, "%s", "initialization not performed due to errors");
        dasd_exit();
        return rc;
}

module_init(dasd_init);
module_exit(dasd_exit);

EXPORT_SYMBOL(dasd_debug_area);
EXPORT_SYMBOL(dasd_diag_discipline_pointer);

EXPORT_SYMBOL(dasd_add_request_head);
EXPORT_SYMBOL(dasd_add_request_tail);
EXPORT_SYMBOL(dasd_cancel_req);
EXPORT_SYMBOL(dasd_clear_timer);
EXPORT_SYMBOL(dasd_enable_device);
EXPORT_SYMBOL(dasd_int_handler);
EXPORT_SYMBOL(dasd_kfree_request);
EXPORT_SYMBOL(dasd_kick_device);
EXPORT_SYMBOL(dasd_kmalloc_request);
EXPORT_SYMBOL(dasd_schedule_bh);
EXPORT_SYMBOL(dasd_set_target_state);
EXPORT_SYMBOL(dasd_set_timer);
EXPORT_SYMBOL(dasd_sfree_request);
EXPORT_SYMBOL(dasd_sleep_on);
EXPORT_SYMBOL(dasd_sleep_on_immediatly);
EXPORT_SYMBOL(dasd_sleep_on_interruptible);
EXPORT_SYMBOL(dasd_smalloc_request);
EXPORT_SYMBOL(dasd_start_IO);
EXPORT_SYMBOL(dasd_term_IO);

EXPORT_SYMBOL_GPL(dasd_generic_probe);
EXPORT_SYMBOL_GPL(dasd_generic_remove);
EXPORT_SYMBOL_GPL(dasd_generic_notify);
EXPORT_SYMBOL_GPL(dasd_generic_set_online);
EXPORT_SYMBOL_GPL(dasd_generic_set_offline);