System call wrappers part 05

[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / drivers / s390 / char / vmur.c

/*
 * Linux driver for System z and s390 unit record devices
 * (z/VM virtual punch, reader, printer)
 *
 * Copyright IBM Corp. 2001, 2007
 * Authors: Malcolm Beattie <beattiem@uk.ibm.com>
 *          Michael Holzheu <holzheu@de.ibm.com>
 *          Frank Munzert <munzert@de.ibm.com>
 */

#include <linux/cdev.h>
#include <linux/smp_lock.h>

#include <asm/uaccess.h>
#include <asm/cio.h>
#include <asm/ccwdev.h>
#include <asm/debug.h>
#include <asm/diag.h>

#include "vmur.h"

/*
 * Driver overview
 *
 * Unit record device support is implemented as a character device driver.
 * We can fit at least 16 bits into a device minor number and use the
 * simple method of mapping a character device number with minor abcd
 * to the unit record device with devno abcd.
 * I/O to virtual unit record devices is handled as follows:
 * Reads: Diagnose code 0x14 (input spool file manipulation)
 * is used to read spool data page-wise.
 * Writes: The CCW used is WRITE_CCW_CMD (0x01). The device's record length
 * is available by reading sysfs attr reclen. Each write() to the device
 * must specify an integral multiple (maximal 511) of reclen.
 */

static char ur_banner[] = "z/VM virtual unit record device driver";

MODULE_AUTHOR("IBM Corporation");
MODULE_DESCRIPTION("s390 z/VM virtual unit record device driver");
MODULE_LICENSE("GPL");

#define PRINTK_HEADER "vmur: "

static dev_t ur_first_dev_maj_min;
static struct class *vmur_class;
static struct debug_info *vmur_dbf;

/* We put the device's record length (for writes) in the driver_info field */
static struct ccw_device_id ur_ids[] = {
        { CCWDEV_CU_DI(READER_PUNCH_DEVTYPE, 80) },
        { CCWDEV_CU_DI(PRINTER_DEVTYPE, 132) },
        { /* end of list */ }
};

MODULE_DEVICE_TABLE(ccw, ur_ids);

static int ur_probe(struct ccw_device *cdev);
static void ur_remove(struct ccw_device *cdev);
static int ur_set_online(struct ccw_device *cdev);
static int ur_set_offline(struct ccw_device *cdev);

static struct ccw_driver ur_driver = {
        .name           = "vmur",
        .owner          = THIS_MODULE,
        .ids            = ur_ids,
        .probe          = ur_probe,
        .remove         = ur_remove,
        .set_online     = ur_set_online,
        .set_offline    = ur_set_offline,
};

static DEFINE_MUTEX(vmur_mutex);

/*
 * Allocation, freeing, getting and putting of urdev structures
 *
 * Each ur device (urd) contains a reference to its corresponding ccw device
 * (cdev) using the urd->cdev pointer. Each ccw device has a reference to the
 * ur device using the cdev->dev.driver_data pointer.
 *
 * urd references:
 * - ur_probe gets a urd reference, ur_remove drops the reference
 *   (cdev->dev.driver_data)
 * - ur_open gets a urd reference, ur_relase drops the reference
 *   (urf->urd)
 *
 * cdev references:
 * - urdev_alloc get a cdev reference (urd->cdev)
 * - urdev_free drops the cdev reference (urd->cdev)
 *
 * Setting and clearing of cdev->dev.driver_data is protected by the ccwdev lock
 */
static struct urdev *urdev_alloc(struct ccw_device *cdev)
{
        struct urdev *urd;

        urd = kzalloc(sizeof(struct urdev), GFP_KERNEL);
        if (!urd)
                return NULL;
        urd->reclen = cdev->id.driver_info;
        ccw_device_get_id(cdev, &urd->dev_id);
        mutex_init(&urd->io_mutex);
        init_waitqueue_head(&urd->wait);
        spin_lock_init(&urd->open_lock);
        atomic_set(&urd->ref_count,  1);
        urd->cdev = cdev;
        get_device(&cdev->dev);
        return urd;
}

static void urdev_free(struct urdev *urd)
{
        TRACE("urdev_free: %p\n", urd);
        if (urd->cdev)
                put_device(&urd->cdev->dev);
        kfree(urd);
}

static void urdev_get(struct urdev *urd)
{
        atomic_inc(&urd->ref_count);
}

static struct urdev *urdev_get_from_cdev(struct ccw_device *cdev)
{
        struct urdev *urd;
        unsigned long flags;

        spin_lock_irqsave(get_ccwdev_lock(cdev), flags);
        urd = cdev->dev.driver_data;
        if (urd)
                urdev_get(urd);
        spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);
        return urd;
}

static struct urdev *urdev_get_from_devno(u16 devno)
{
        char bus_id[16];
        struct ccw_device *cdev;
        struct urdev *urd;

        sprintf(bus_id, "0.0.%04x", devno);
        cdev = get_ccwdev_by_busid(&ur_driver, bus_id);
        if (!cdev)
                return NULL;
        urd = urdev_get_from_cdev(cdev);
        put_device(&cdev->dev);
        return urd;
}

static void urdev_put(struct urdev *urd)
{
        if (atomic_dec_and_test(&urd->ref_count))
                urdev_free(urd);
}

/*
 * Low-level functions to do I/O to a ur device.
 *     alloc_chan_prog
 *     free_chan_prog
 *     do_ur_io
 *     ur_int_handler
 *
 * alloc_chan_prog allocates and builds the channel program
 * free_chan_prog frees memory of the channel program
 *
 * do_ur_io issues the channel program to the device and blocks waiting
 * on a completion event it publishes at urd->io_done. The function
 * serialises itself on the device's mutex so that only one I/O
 * is issued at a time (and that I/O is synchronous).
 *
 * ur_int_handler catches the "I/O done" interrupt, writes the
 * subchannel status word into the scsw member of the urdev structure
 * and complete()s the io_done to wake the waiting do_ur_io.
 *
 * The caller of do_ur_io is responsible for kfree()ing the channel program
 * address pointer that alloc_chan_prog returned.
 */

static void free_chan_prog(struct ccw1 *cpa)
{
        struct ccw1 *ptr = cpa;

        while (ptr->cda) {
                kfree((void *)(addr_t) ptr->cda);
                ptr++;
        }
        kfree(cpa);
}

/*
 * alloc_chan_prog
 * The channel program we use is write commands chained together
 * with a final NOP CCW command-chained on (which ensures that CE and DE
 * are presented together in a single interrupt instead of as separate
 * interrupts unless an incorrect length indication kicks in first). The
 * data length in each CCW is reclen.
 */
static struct ccw1 *alloc_chan_prog(const char __user *ubuf, int rec_count,
                                    int reclen)
{
        struct ccw1 *cpa;
        void *kbuf;
        int i;

        TRACE("alloc_chan_prog(%p, %i, %i)\n", ubuf, rec_count, reclen);

        /*
         * We chain a NOP onto the writes to force CE+DE together.
         * That means we allocate room for CCWs to cover count/reclen
         * records plus a NOP.
         */
        cpa = kzalloc((rec_count + 1) * sizeof(struct ccw1),
                      GFP_KERNEL | GFP_DMA);
        if (!cpa)
                return ERR_PTR(-ENOMEM);

        for (i = 0; i < rec_count; i++) {
                cpa[i].cmd_code = WRITE_CCW_CMD;
                cpa[i].flags = CCW_FLAG_CC | CCW_FLAG_SLI;
                cpa[i].count = reclen;
                kbuf = kmalloc(reclen, GFP_KERNEL | GFP_DMA);
                if (!kbuf) {
                        free_chan_prog(cpa);
                        return ERR_PTR(-ENOMEM);
                }
                cpa[i].cda = (u32)(addr_t) kbuf;
                if (copy_from_user(kbuf, ubuf, reclen)) {
                        free_chan_prog(cpa);
                        return ERR_PTR(-EFAULT);
                }
                ubuf += reclen;
        }
        /* The following NOP CCW forces CE+DE to be presented together */
        cpa[i].cmd_code = CCW_CMD_NOOP;
        return cpa;
}

static int do_ur_io(struct urdev *urd, struct ccw1 *cpa)
{
        int rc;
        struct ccw_device *cdev = urd->cdev;
        DECLARE_COMPLETION_ONSTACK(event);

        TRACE("do_ur_io: cpa=%p\n", cpa);

        rc = mutex_lock_interruptible(&urd->io_mutex);
        if (rc)
                return rc;

        urd->io_done = &event;

        spin_lock_irq(get_ccwdev_lock(cdev));
        rc = ccw_device_start(cdev, cpa, 1, 0, 0);
        spin_unlock_irq(get_ccwdev_lock(cdev));

        TRACE("do_ur_io: ccw_device_start returned %d\n", rc);
        if (rc)
                goto out;

        wait_for_completion(&event);
        TRACE("do_ur_io: I/O complete\n");
        rc = 0;

out:
        mutex_unlock(&urd->io_mutex);
        return rc;
}

/*
 * ur interrupt handler, called from the ccw_device layer
 */
static void ur_int_handler(struct ccw_device *cdev, unsigned long intparm,
                           struct irb *irb)
{
        struct urdev *urd;

        TRACE("ur_int_handler: intparm=0x%lx cstat=%02x dstat=%02x res=%u\n",
              intparm, irb->scsw.cmd.cstat, irb->scsw.cmd.dstat,
              irb->scsw.cmd.count);

        if (!intparm) {
                TRACE("ur_int_handler: unsolicited interrupt\n");
                return;
        }
        urd = cdev->dev.driver_data;
        BUG_ON(!urd);
        /* On special conditions irb is an error pointer */
        if (IS_ERR(irb))
                urd->io_request_rc = PTR_ERR(irb);
        else if (irb->scsw.cmd.dstat == (DEV_STAT_CHN_END | DEV_STAT_DEV_END))
                urd->io_request_rc = 0;
        else
                urd->io_request_rc = -EIO;

        complete(urd->io_done);
}

/*
 * reclen sysfs attribute - The record length to be used for write CCWs
 */
static ssize_t ur_attr_reclen_show(struct device *dev,
                                   struct device_attribute *attr, char *buf)
{
        struct urdev *urd;
        int rc;

        urd = urdev_get_from_cdev(to_ccwdev(dev));
        if (!urd)
                return -ENODEV;
        rc = sprintf(buf, "%zu\n", urd->reclen);
        urdev_put(urd);
        return rc;
}

static DEVICE_ATTR(reclen, 0444, ur_attr_reclen_show, NULL);

static int ur_create_attributes(struct device *dev)
{
        return device_create_file(dev, &dev_attr_reclen);
}

static void ur_remove_attributes(struct device *dev)
{
        device_remove_file(dev, &dev_attr_reclen);
}

/*
 * diagnose code 0x210 - retrieve device information
 * cc=0  normal completion, we have a real device
 * cc=1  CP paging error
 * cc=2  The virtual device exists, but is not associated with a real device
 * cc=3  Invalid device address, or the virtual device does not exist
 */
static int get_urd_class(struct urdev *urd)
{
        static struct diag210 ur_diag210;
        int cc;

        ur_diag210.vrdcdvno = urd->dev_id.devno;
        ur_diag210.vrdclen = sizeof(struct diag210);

        cc = diag210(&ur_diag210);
        switch (cc) {
        case 0:
                return -EOPNOTSUPP;
        case 2:
                return ur_diag210.vrdcvcla; /* virtual device class */
        case 3:
                return -ENODEV;
        default:
                return -EIO;
        }
}

/*
 * Allocation and freeing of urfile structures
 */
static struct urfile *urfile_alloc(struct urdev *urd)
{
        struct urfile *urf;

        urf = kzalloc(sizeof(struct urfile), GFP_KERNEL);
        if (!urf)
                return NULL;
        urf->urd = urd;

        TRACE("urfile_alloc: urd=%p urf=%p rl=%zu\n", urd, urf,
              urf->dev_reclen);

        return urf;
}

static void urfile_free(struct urfile *urf)
{
        TRACE("urfile_free: urf=%p urd=%p\n", urf, urf->urd);
        kfree(urf);
}

/*
 * The fops implementation of the character device driver
 */
static ssize_t do_write(struct urdev *urd, const char __user *udata,
                        size_t count, size_t reclen, loff_t *ppos)
{
        struct ccw1 *cpa;
        int rc;

        cpa = alloc_chan_prog(udata, count / reclen, reclen);
        if (IS_ERR(cpa))
                return PTR_ERR(cpa);

        rc = do_ur_io(urd, cpa);
        if (rc)
                goto fail_kfree_cpa;

        if (urd->io_request_rc) {
                rc = urd->io_request_rc;
                goto fail_kfree_cpa;
        }
        *ppos += count;
        rc = count;

fail_kfree_cpa:
        free_chan_prog(cpa);
        return rc;
}

static ssize_t ur_write(struct file *file, const char __user *udata,
                        size_t count, loff_t *ppos)
{
        struct urfile *urf = file->private_data;

        TRACE("ur_write: count=%zu\n", count);

        if (count == 0)
                return 0;

        if (count % urf->dev_reclen)
                return -EINVAL; /* count must be a multiple of reclen */

        if (count > urf->dev_reclen * MAX_RECS_PER_IO)
                count = urf->dev_reclen * MAX_RECS_PER_IO;

        return do_write(urf->urd, udata, count, urf->dev_reclen, ppos);
}

/*
 * diagnose code 0x14 subcode 0x0028 - position spool file to designated
 *                                     record
 * cc=0  normal completion
 * cc=2  no file active on the virtual reader or device not ready
 * cc=3  record specified is beyond EOF
 */
static int diag_position_to_record(int devno, int record)
{
        int cc;

        cc = diag14(record, devno, 0x28);
        switch (cc) {
        case 0:
                return 0;
        case 2:
                return -ENOMEDIUM;
        case 3:
                return -ENODATA; /* position beyond end of file */
        default:
                return -EIO;
        }
}

/*
 * diagnose code 0x14 subcode 0x0000 - read next spool file buffer
 * cc=0  normal completion
 * cc=1  EOF reached
 * cc=2  no file active on the virtual reader, and no file eligible
 * cc=3  file already active on the virtual reader or specified virtual
 *       reader does not exist or is not a reader
 */
static int diag_read_file(int devno, char *buf)
{
        int cc;

        cc = diag14((unsigned long) buf, devno, 0x00);
        switch (cc) {
        case 0:
                return 0;
        case 1:
                return -ENODATA;
        case 2:
                return -ENOMEDIUM;
        default:
                return -EIO;
        }
}

static ssize_t diag14_read(struct file *file, char __user *ubuf, size_t count,
                           loff_t *offs)
{
        size_t len, copied, res;
        char *buf;
        int rc;
        u16 reclen;
        struct urdev *urd;

        urd = ((struct urfile *) file->private_data)->urd;
        reclen = ((struct urfile *) file->private_data)->file_reclen;

        rc = diag_position_to_record(urd->dev_id.devno, *offs / PAGE_SIZE + 1);
        if (rc == -ENODATA)
                return 0;
        if (rc)
                return rc;

        len = min((size_t) PAGE_SIZE, count);
        buf = (char *) __get_free_page(GFP_KERNEL | GFP_DMA);
        if (!buf)
                return -ENOMEM;

        copied = 0;
        res = (size_t) (*offs % PAGE_SIZE);
        do {
                rc = diag_read_file(urd->dev_id.devno, buf);
                if (rc == -ENODATA) {
                        break;
                }
                if (rc)
                        goto fail;
                if (reclen && (copied == 0) && (*offs < PAGE_SIZE))
                        *((u16 *) &buf[FILE_RECLEN_OFFSET]) = reclen;
                len = min(count - copied, PAGE_SIZE - res);
                if (copy_to_user(ubuf + copied, buf + res, len)) {
                        rc = -EFAULT;
                        goto fail;
                }
                res = 0;
                copied += len;
        } while (copied != count);

        *offs += copied;
        rc = copied;
fail:
        free_page((unsigned long) buf);
        return rc;
}

static ssize_t ur_read(struct file *file, char __user *ubuf, size_t count,
                       loff_t *offs)
{
        struct urdev *urd;
        int rc;

        TRACE("ur_read: count=%zu ppos=%li\n", count, (unsigned long) *offs);

        if (count == 0)
                return 0;

        urd = ((struct urfile *) file->private_data)->urd;
        rc = mutex_lock_interruptible(&urd->io_mutex);
        if (rc)
                return rc;
        rc = diag14_read(file, ubuf, count, offs);
        mutex_unlock(&urd->io_mutex);
        return rc;
}

/*
 * diagnose code 0x14 subcode 0x0fff - retrieve next file descriptor
 * cc=0  normal completion
 * cc=1  no files on reader queue or no subsequent file
 * cc=2  spid specified is invalid
 */
static int diag_read_next_file_info(struct file_control_block *buf, int spid)
{
        int cc;

        cc = diag14((unsigned long) buf, spid, 0xfff);
        switch (cc) {
        case 0:
                return 0;
        default:
                return -ENODATA;
        }
}

static int verify_uri_device(struct urdev *urd)
{
        struct file_control_block *fcb;
        char *buf;
        int rc;

        fcb = kmalloc(sizeof(*fcb), GFP_KERNEL | GFP_DMA);
        if (!fcb)
                return -ENOMEM;

        /* check for empty reader device (beginning of chain) */
        rc = diag_read_next_file_info(fcb, 0);
        if (rc)
                goto fail_free_fcb;

        /* if file is in hold status, we do not read it */
        if (fcb->file_stat & (FLG_SYSTEM_HOLD | FLG_USER_HOLD)) {
                rc = -EPERM;
                goto fail_free_fcb;
        }

        /* open file on virtual reader  */
        buf = (char *) __get_free_page(GFP_KERNEL | GFP_DMA);
        if (!buf) {
                rc = -ENOMEM;
                goto fail_free_fcb;
        }
        rc = diag_read_file(urd->dev_id.devno, buf);
        if ((rc != 0) && (rc != -ENODATA)) /* EOF does not hurt */
                goto fail_free_buf;

        /* check if the file on top of the queue is open now */
        rc = diag_read_next_file_info(fcb, 0);
        if (rc)
                goto fail_free_buf;
        if (!(fcb->file_stat & FLG_IN_USE)) {
                rc = -EMFILE;
                goto fail_free_buf;
        }
        rc = 0;

fail_free_buf:
        free_page((unsigned long) buf);
fail_free_fcb:
        kfree(fcb);
        return rc;
}

static int verify_device(struct urdev *urd)
{
        switch (urd->class) {
        case DEV_CLASS_UR_O:
                return 0; /* no check needed here */
        case DEV_CLASS_UR_I:
                return verify_uri_device(urd);
        default:
                return -EOPNOTSUPP;
        }
}

static int get_uri_file_reclen(struct urdev *urd)
{
        struct file_control_block *fcb;
        int rc;

        fcb = kmalloc(sizeof(*fcb), GFP_KERNEL | GFP_DMA);
        if (!fcb)
                return -ENOMEM;
        rc = diag_read_next_file_info(fcb, 0);
        if (rc)
                goto fail_free;
        if (fcb->file_stat & FLG_CP_DUMP)
                rc = 0;
        else
                rc = fcb->rec_len;

fail_free:
        kfree(fcb);
        return rc;
}

static int get_file_reclen(struct urdev *urd)
{
        switch (urd->class) {
        case DEV_CLASS_UR_O:
                return 0;
        case DEV_CLASS_UR_I:
                return get_uri_file_reclen(urd);
        default:
                return -EOPNOTSUPP;
        }
}

static int ur_open(struct inode *inode, struct file *file)
{
        u16 devno;
        struct urdev *urd;
        struct urfile *urf;
        unsigned short accmode;
        int rc;

        accmode = file->f_flags & O_ACCMODE;

        if (accmode == O_RDWR)
                return -EACCES;
        lock_kernel();
        /*
         * We treat the minor number as the devno of the ur device
         * to find in the driver tree.
         */
        devno = MINOR(file->f_dentry->d_inode->i_rdev);

        urd = urdev_get_from_devno(devno);
        if (!urd) {
                rc = -ENXIO;
                goto out;
        }

        spin_lock(&urd->open_lock);
        while (urd->open_flag) {
                spin_unlock(&urd->open_lock);
                if (file->f_flags & O_NONBLOCK) {
                        rc = -EBUSY;
                        goto fail_put;
                }
                if (wait_event_interruptible(urd->wait, urd->open_flag == 0)) {
                        rc = -ERESTARTSYS;
                        goto fail_put;
                }
                spin_lock(&urd->open_lock);
        }
        urd->open_flag++;
        spin_unlock(&urd->open_lock);

        TRACE("ur_open\n");

        if (((accmode == O_RDONLY) && (urd->class != DEV_CLASS_UR_I)) ||
            ((accmode == O_WRONLY) && (urd->class != DEV_CLASS_UR_O))) {
                TRACE("ur_open: unsupported dev class (%d)\n", urd->class);
                rc = -EACCES;
                goto fail_unlock;
        }

        rc = verify_device(urd);
        if (rc)
                goto fail_unlock;

        urf = urfile_alloc(urd);
        if (!urf) {
                rc = -ENOMEM;
                goto fail_unlock;
        }

        urf->dev_reclen = urd->reclen;
        rc = get_file_reclen(urd);
        if (rc < 0)
                goto fail_urfile_free;
        urf->file_reclen = rc;
        file->private_data = urf;
        unlock_kernel();
        return 0;

fail_urfile_free:
        urfile_free(urf);
fail_unlock:
        spin_lock(&urd->open_lock);
        urd->open_flag--;
        spin_unlock(&urd->open_lock);
fail_put:
        urdev_put(urd);
out:
        unlock_kernel();
        return rc;
}

static int ur_release(struct inode *inode, struct file *file)
{
        struct urfile *urf = file->private_data;

        TRACE("ur_release\n");
        spin_lock(&urf->urd->open_lock);
        urf->urd->open_flag--;
        spin_unlock(&urf->urd->open_lock);
        wake_up_interruptible(&urf->urd->wait);
        urdev_put(urf->urd);
        urfile_free(urf);
        return 0;
}

static loff_t ur_llseek(struct file *file, loff_t offset, int whence)
{
        loff_t newpos;

        if ((file->f_flags & O_ACCMODE) != O_RDONLY)
                return -ESPIPE; /* seek allowed only for reader */
        if (offset % PAGE_SIZE)
                return -ESPIPE; /* only multiples of 4K allowed */
        switch (whence) {
        case 0: /* SEEK_SET */
                newpos = offset;
                break;
        case 1: /* SEEK_CUR */
                newpos = file->f_pos + offset;
                break;
        default:
                return -EINVAL;
        }
        file->f_pos = newpos;
        return newpos;
}

static const struct file_operations ur_fops = {
        .owner   = THIS_MODULE,
        .open    = ur_open,
        .release = ur_release,
        .read    = ur_read,
        .write   = ur_write,
        .llseek  = ur_llseek,
};

/*
 * ccw_device infrastructure:
 *     ur_probe creates the struct urdev (with refcount = 1), the device
 *     attributes, sets up the interrupt handler and validates the virtual
 *     unit record device.
 *     ur_remove removes the device attributes and drops the reference to
 *     struct urdev.
 *
 *     ur_probe, ur_remove, ur_set_online and ur_set_offline are serialized
 *     by the vmur_mutex lock.
 *
 *     urd->char_device is used as indication that the online function has
 *     been completed successfully.
 */
static int ur_probe(struct ccw_device *cdev)
{
        struct urdev *urd;
        int rc;

        TRACE("ur_probe: cdev=%p\n", cdev);

        mutex_lock(&vmur_mutex);
        urd = urdev_alloc(cdev);
        if (!urd) {
                rc = -ENOMEM;
                goto fail_unlock;
        }

        rc = ur_create_attributes(&cdev->dev);
        if (rc) {
                rc = -ENOMEM;
                goto fail_urdev_put;
        }
        cdev->handler = ur_int_handler;

        /* validate virtual unit record device */
        urd->class = get_urd_class(urd);
        if (urd->class < 0) {
                rc = urd->class;
                goto fail_remove_attr;
        }
        if ((urd->class != DEV_CLASS_UR_I) && (urd->class != DEV_CLASS_UR_O)) {
                rc = -EOPNOTSUPP;
                goto fail_remove_attr;
        }
        spin_lock_irq(get_ccwdev_lock(cdev));
        cdev->dev.driver_data = urd;
        spin_unlock_irq(get_ccwdev_lock(cdev));

        mutex_unlock(&vmur_mutex);
        return 0;

fail_remove_attr:
        ur_remove_attributes(&cdev->dev);
fail_urdev_put:
        urdev_put(urd);
fail_unlock:
        mutex_unlock(&vmur_mutex);
        return rc;
}

static int ur_set_online(struct ccw_device *cdev)
{
        struct urdev *urd;
        int minor, major, rc;
        char node_id[16];

        TRACE("ur_set_online: cdev=%p\n", cdev);

        mutex_lock(&vmur_mutex);
        urd = urdev_get_from_cdev(cdev);
        if (!urd) {
                /* ur_remove already deleted our urd */
                rc = -ENODEV;
                goto fail_unlock;
        }

        if (urd->char_device) {
                /* Another ur_set_online was faster */
                rc = -EBUSY;
                goto fail_urdev_put;
        }

        minor = urd->dev_id.devno;
        major = MAJOR(ur_first_dev_maj_min);

        urd->char_device = cdev_alloc();
        if (!urd->char_device) {
                rc = -ENOMEM;
                goto fail_urdev_put;
        }

        cdev_init(urd->char_device, &ur_fops);
        urd->char_device->dev = MKDEV(major, minor);
        urd->char_device->owner = ur_fops.owner;

        rc = cdev_add(urd->char_device, urd->char_device->dev, 1);
        if (rc)
                goto fail_free_cdev;
        if (urd->cdev->id.cu_type == READER_PUNCH_DEVTYPE) {
                if (urd->class == DEV_CLASS_UR_I)
                        sprintf(node_id, "vmrdr-%s", cdev->dev.bus_id);
                if (urd->class == DEV_CLASS_UR_O)
                        sprintf(node_id, "vmpun-%s", cdev->dev.bus_id);
        } else if (urd->cdev->id.cu_type == PRINTER_DEVTYPE) {
                sprintf(node_id, "vmprt-%s", cdev->dev.bus_id);
        } else {
                rc = -EOPNOTSUPP;
                goto fail_free_cdev;
        }

        urd->device = device_create_drvdata(vmur_class, NULL,
                                            urd->char_device->dev, NULL,
                                            "%s", node_id);
        if (IS_ERR(urd->device)) {
                rc = PTR_ERR(urd->device);
                TRACE("ur_set_online: device_create rc=%d\n", rc);
                goto fail_free_cdev;
        }
        urdev_put(urd);
        mutex_unlock(&vmur_mutex);
        return 0;

fail_free_cdev:
        cdev_del(urd->char_device);
        urd->char_device = NULL;
fail_urdev_put:
        urdev_put(urd);
fail_unlock:
        mutex_unlock(&vmur_mutex);
        return rc;
}

static int ur_set_offline_force(struct ccw_device *cdev, int force)
{
        struct urdev *urd;
        int rc;

        TRACE("ur_set_offline: cdev=%p\n", cdev);
        urd = urdev_get_from_cdev(cdev);
        if (!urd)
                /* ur_remove already deleted our urd */
                return -ENODEV;
        if (!urd->char_device) {
                /* Another ur_set_offline was faster */
                rc = -EBUSY;
                goto fail_urdev_put;
        }
        if (!force && (atomic_read(&urd->ref_count) > 2)) {
                /* There is still a user of urd (e.g. ur_open) */
                TRACE("ur_set_offline: BUSY\n");
                rc = -EBUSY;
                goto fail_urdev_put;
        }
        device_destroy(vmur_class, urd->char_device->dev);
        cdev_del(urd->char_device);
        urd->char_device = NULL;
        rc = 0;

fail_urdev_put:
        urdev_put(urd);
        return rc;
}

static int ur_set_offline(struct ccw_device *cdev)
{
        int rc;

        mutex_lock(&vmur_mutex);
        rc = ur_set_offline_force(cdev, 0);
        mutex_unlock(&vmur_mutex);
        return rc;
}

static void ur_remove(struct ccw_device *cdev)
{
        unsigned long flags;

        TRACE("ur_remove\n");

        mutex_lock(&vmur_mutex);

        if (cdev->online)
                ur_set_offline_force(cdev, 1);
        ur_remove_attributes(&cdev->dev);

        spin_lock_irqsave(get_ccwdev_lock(cdev), flags);
        urdev_put(cdev->dev.driver_data);
        cdev->dev.driver_data = NULL;
        spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);

        mutex_unlock(&vmur_mutex);
}

/*
 * Module initialisation and cleanup
 */
static int __init ur_init(void)
{
        int rc;
        dev_t dev;

        if (!MACHINE_IS_VM) {
                PRINT_ERR("%s is only available under z/VM.\n", ur_banner);
                return -ENODEV;
        }

        vmur_dbf = debug_register("vmur", 4, 1, 4 * sizeof(long));
        if (!vmur_dbf)
                return -ENOMEM;
        rc = debug_register_view(vmur_dbf, &debug_sprintf_view);
        if (rc)
                goto fail_free_dbf;

        debug_set_level(vmur_dbf, 6);

        rc = ccw_driver_register(&ur_driver);
        if (rc)
                goto fail_free_dbf;

        rc = alloc_chrdev_region(&dev, 0, NUM_MINORS, "vmur");
        if (rc) {
                PRINT_ERR("alloc_chrdev_region failed: err = %d\n", rc);
                goto fail_unregister_driver;
        }
        ur_first_dev_maj_min = MKDEV(MAJOR(dev), 0);

        vmur_class = class_create(THIS_MODULE, "vmur");
        if (IS_ERR(vmur_class)) {
                rc = PTR_ERR(vmur_class);
                goto fail_unregister_region;
        }
        PRINT_INFO("%s loaded.\n", ur_banner);
        return 0;

fail_unregister_region:
        unregister_chrdev_region(ur_first_dev_maj_min, NUM_MINORS);
fail_unregister_driver:
        ccw_driver_unregister(&ur_driver);
fail_free_dbf:
        debug_unregister(vmur_dbf);
        return rc;
}

static void __exit ur_exit(void)
{
        class_destroy(vmur_class);
        unregister_chrdev_region(ur_first_dev_maj_min, NUM_MINORS);
        ccw_driver_unregister(&ur_driver);
        debug_unregister(vmur_dbf);
        PRINT_INFO("%s unloaded.\n", ur_banner);
}

module_init(ur_init);
module_exit(ur_exit);