/*
    comedi/comedi_fops.c
    comedi kernel module

    COMEDI - Linux Control and Measurement Device Interface
    Copyright (C) 1997-2000 David A. Schleef <ds@schleef.org>

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
*/

#include "comedi_compat32.h"

#include <linux/module.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/fcntl.h>
#include <linux/delay.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/kmod.h>
#include <linux/poll.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/vmalloc.h>
#include <linux/fs.h>
#include "comedidev.h"
#include <linux/cdev.h>
#include <linux/stat.h>

#include <linux/io.h>
#include <linux/uaccess.h>

#include "comedi_internal.h"

#define COMEDI_NUM_MINORS 0x100
#define COMEDI_NUM_SUBDEVICE_MINORS     \
        (COMEDI_NUM_MINORS - COMEDI_NUM_BOARD_MINORS)

static int comedi_num_legacy_minors;
module_param(comedi_num_legacy_minors, int, S_IRUGO);
MODULE_PARM_DESC(comedi_num_legacy_minors,
                 "number of comedi minor devices to reserve for non-auto-configured devices (default 0)"
                );

unsigned int comedi_default_buf_size_kb = CONFIG_COMEDI_DEFAULT_BUF_SIZE_KB;
module_param(comedi_default_buf_size_kb, uint, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(comedi_default_buf_size_kb,
                 "default asynchronous buffer size in KiB (default "
                 __MODULE_STRING(CONFIG_COMEDI_DEFAULT_BUF_SIZE_KB) ")");

unsigned int comedi_default_buf_maxsize_kb
        = CONFIG_COMEDI_DEFAULT_BUF_MAXSIZE_KB;
module_param(comedi_default_buf_maxsize_kb, uint, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(comedi_default_buf_maxsize_kb,
                 "default maximum size of asynchronous buffer in KiB (default "
                 __MODULE_STRING(CONFIG_COMEDI_DEFAULT_BUF_MAXSIZE_KB) ")");

static DEFINE_MUTEX(comedi_board_minor_table_lock);
static struct comedi_device
*comedi_board_minor_table[COMEDI_NUM_BOARD_MINORS];

static DEFINE_MUTEX(comedi_subdevice_minor_table_lock);
/* Note: indexed by minor - COMEDI_NUM_BOARD_MINORS. */
static struct comedi_subdevice
*comedi_subdevice_minor_table[COMEDI_NUM_SUBDEVICE_MINORS];

static struct class *comedi_class;
static struct cdev comedi_cdev;

static void comedi_device_init(struct comedi_device *dev)
{
        kref_init(&dev->refcount);
        spin_lock_init(&dev->spinlock);
        mutex_init(&dev->mutex);
        init_rwsem(&dev->attach_lock);
        dev->minor = -1;
}

static void comedi_dev_kref_release(struct kref *kref)
{
        struct comedi_device *dev =
                container_of(kref, struct comedi_device, refcount);

        mutex_destroy(&dev->mutex);
        put_device(dev->class_dev);
        kfree(dev);
}

int comedi_dev_put(struct comedi_device *dev)
{
        if (dev)
                return kref_put(&dev->refcount, comedi_dev_kref_release);
        return 1;
}
EXPORT_SYMBOL_GPL(comedi_dev_put);

static struct comedi_device *comedi_dev_get(struct comedi_device *dev)
{
        if (dev)
                kref_get(&dev->refcount);
        return dev;
}

static void comedi_device_cleanup(struct comedi_device *dev)
{
        struct module *driver_module = NULL;

        if (dev == NULL)
                return;
        mutex_lock(&dev->mutex);
        if (dev->attached)
                driver_module = dev->driver->module;
        comedi_device_detach(dev);
        if (driver_module && dev->use_count)
                module_put(driver_module);
        mutex_unlock(&dev->mutex);
}

static bool comedi_clear_board_dev(struct comedi_device *dev)
{
        unsigned int i = dev->minor;
        bool cleared = false;

        mutex_lock(&comedi_board_minor_table_lock);
        if (dev == comedi_board_minor_table[i]) {
                comedi_board_minor_table[i] = NULL;
                cleared = true;
        }
        mutex_unlock(&comedi_board_minor_table_lock);
        return cleared;
}

static struct comedi_device *comedi_clear_board_minor(unsigned minor)
{
        struct comedi_device *dev;

        mutex_lock(&comedi_board_minor_table_lock);
        dev = comedi_board_minor_table[minor];
        comedi_board_minor_table[minor] = NULL;
        mutex_unlock(&comedi_board_minor_table_lock);
        return dev;
}

static void comedi_free_board_dev(struct comedi_device *dev)
{
        if (dev) {
                comedi_device_cleanup(dev);
                if (dev->class_dev) {
                        device_destroy(comedi_class,
                                       MKDEV(COMEDI_MAJOR, dev->minor));
                }
                comedi_dev_put(dev);
        }
}

static struct comedi_subdevice
*comedi_subdevice_from_minor(const struct comedi_device *dev, unsigned minor)
{
        struct comedi_subdevice *s;
        unsigned int i = minor - COMEDI_NUM_BOARD_MINORS;

        BUG_ON(i >= COMEDI_NUM_SUBDEVICE_MINORS);
        mutex_lock(&comedi_subdevice_minor_table_lock);
        s = comedi_subdevice_minor_table[i];
        if (s && s->device != dev)
                s = NULL;
        mutex_unlock(&comedi_subdevice_minor_table_lock);
        return s;
}

static struct comedi_device *comedi_dev_get_from_board_minor(unsigned minor)
{
        struct comedi_device *dev;

        BUG_ON(minor >= COMEDI_NUM_BOARD_MINORS);
        mutex_lock(&comedi_board_minor_table_lock);
        dev = comedi_dev_get(comedi_board_minor_table[minor]);
        mutex_unlock(&comedi_board_minor_table_lock);
        return dev;
}

static struct comedi_device *comedi_dev_get_from_subdevice_minor(unsigned minor)
{
        struct comedi_device *dev;
        struct comedi_subdevice *s;
        unsigned int i = minor - COMEDI_NUM_BOARD_MINORS;

        BUG_ON(i >= COMEDI_NUM_SUBDEVICE_MINORS);
        mutex_lock(&comedi_subdevice_minor_table_lock);
        s = comedi_subdevice_minor_table[i];
        dev = comedi_dev_get(s ? s->device : NULL);
        mutex_unlock(&comedi_subdevice_minor_table_lock);
        return dev;
}

struct comedi_device *comedi_dev_get_from_minor(unsigned minor)
{
        if (minor < COMEDI_NUM_BOARD_MINORS)
                return comedi_dev_get_from_board_minor(minor);
        else
                return comedi_dev_get_from_subdevice_minor(minor);
}
EXPORT_SYMBOL_GPL(comedi_dev_get_from_minor);

static struct comedi_subdevice *
comedi_read_subdevice(const struct comedi_device *dev, unsigned int minor)
{
        struct comedi_subdevice *s;

        if (minor >= COMEDI_NUM_BOARD_MINORS) {
                s = comedi_subdevice_from_minor(dev, minor);
                if (s == NULL || (s->subdev_flags & SDF_CMD_READ))
                        return s;
        }
        return dev->read_subdev;
}

static struct comedi_subdevice *
comedi_write_subdevice(const struct comedi_device *dev, unsigned int minor)
{
        struct comedi_subdevice *s;

        if (minor >= COMEDI_NUM_BOARD_MINORS) {
                s = comedi_subdevice_from_minor(dev, minor);
                if (s == NULL || (s->subdev_flags & SDF_CMD_WRITE))
                        return s;
        }
        return dev->write_subdev;
}

static int resize_async_buffer(struct comedi_device *dev,
                               struct comedi_subdevice *s,
                               struct comedi_async *async, unsigned new_size)
{
        int retval;

        if (new_size > async->max_bufsize)
                return -EPERM;

        if (s->busy) {
                dev_dbg(dev->class_dev,
                        "subdevice is busy, cannot resize buffer\n");
                return -EBUSY;
        }
        if (comedi_buf_is_mmapped(async)) {
                dev_dbg(dev->class_dev,
                        "subdevice is mmapped, cannot resize buffer\n");
                return -EBUSY;
        }

        /* make sure buffer is an integral number of pages
         * (we round up) */
        new_size = (new_size + PAGE_SIZE - 1) & PAGE_MASK;

        retval = comedi_buf_alloc(dev, s, new_size);
        if (retval < 0)
                return retval;

        if (s->buf_change) {
                retval = s->buf_change(dev, s, new_size);
                if (retval < 0)
                        return retval;
        }

        dev_dbg(dev->class_dev, "subd %d buffer resized to %i bytes\n",
                s->index, async->prealloc_bufsz);
        return 0;
}

/* sysfs attribute files */

static ssize_t max_read_buffer_kb_show(struct device *csdev,
                                       struct device_attribute *attr, char *buf)
{
        unsigned int minor = MINOR(csdev->devt);
        struct comedi_device *dev;
        struct comedi_subdevice *s;
        unsigned int size = 0;

        dev = comedi_dev_get_from_minor(minor);
        if (!dev)
                return -ENODEV;

        mutex_lock(&dev->mutex);
        s = comedi_read_subdevice(dev, minor);
        if (s && (s->subdev_flags & SDF_CMD_READ) && s->async)
                size = s->async->max_bufsize / 1024;
        mutex_unlock(&dev->mutex);

        comedi_dev_put(dev);
        return snprintf(buf, PAGE_SIZE, "%i\n", size);
}

static ssize_t max_read_buffer_kb_store(struct device *csdev,
                                        struct device_attribute *attr,
                                        const char *buf, size_t count)
{
        unsigned int minor = MINOR(csdev->devt);
        struct comedi_device *dev;
        struct comedi_subdevice *s;
        unsigned int size;
        int err;

        err = kstrtouint(buf, 10, &size);
        if (err)
                return err;
        if (size > (UINT_MAX / 1024))
                return -EINVAL;
        size *= 1024;

        dev = comedi_dev_get_from_minor(minor);
        if (!dev)
                return -ENODEV;

        mutex_lock(&dev->mutex);
        s = comedi_read_subdevice(dev, minor);
        if (s && (s->subdev_flags & SDF_CMD_READ) && s->async)
                s->async->max_bufsize = size;
        else
                err = -EINVAL;
        mutex_unlock(&dev->mutex);

        comedi_dev_put(dev);
        return err ? err : count;
}
static DEVICE_ATTR_RW(max_read_buffer_kb);

static ssize_t read_buffer_kb_show(struct device *csdev,
                                   struct device_attribute *attr, char *buf)
{
        unsigned int minor = MINOR(csdev->devt);
        struct comedi_device *dev;
        struct comedi_subdevice *s;
        unsigned int size = 0;

        dev = comedi_dev_get_from_minor(minor);
        if (!dev)
                return -ENODEV;

        mutex_lock(&dev->mutex);
        s = comedi_read_subdevice(dev, minor);
        if (s && (s->subdev_flags & SDF_CMD_READ) && s->async)
                size = s->async->prealloc_bufsz / 1024;
        mutex_unlock(&dev->mutex);

        comedi_dev_put(dev);
        return snprintf(buf, PAGE_SIZE, "%i\n", size);
}

static ssize_t read_buffer_kb_store(struct device *csdev,
                                    struct device_attribute *attr,
                                    const char *buf, size_t count)
{
        unsigned int minor = MINOR(csdev->devt);
        struct comedi_device *dev;
        struct comedi_subdevice *s;
        unsigned int size;
        int err;

        err = kstrtouint(buf, 10, &size);
        if (err)
                return err;
        if (size > (UINT_MAX / 1024))
                return -EINVAL;
        size *= 1024;

        dev = comedi_dev_get_from_minor(minor);
        if (!dev)
                return -ENODEV;

        mutex_lock(&dev->mutex);
        s = comedi_read_subdevice(dev, minor);
        if (s && (s->subdev_flags & SDF_CMD_READ) && s->async)
                err = resize_async_buffer(dev, s, s->async, size);
        else
                err = -EINVAL;
        mutex_unlock(&dev->mutex);

        comedi_dev_put(dev);
        return err ? err : count;
}
static DEVICE_ATTR_RW(read_buffer_kb);

static ssize_t max_write_buffer_kb_show(struct device *csdev,
                                        struct device_attribute *attr,
                                        char *buf)
{
        unsigned int minor = MINOR(csdev->devt);
        struct comedi_device *dev;
        struct comedi_subdevice *s;
        unsigned int size = 0;

        dev = comedi_dev_get_from_minor(minor);
        if (!dev)
                return -ENODEV;

        mutex_lock(&dev->mutex);
        s = comedi_write_subdevice(dev, minor);
        if (s && (s->subdev_flags & SDF_CMD_WRITE) && s->async)
                size = s->async->max_bufsize / 1024;
        mutex_unlock(&dev->mutex);

        comedi_dev_put(dev);
        return snprintf(buf, PAGE_SIZE, "%i\n", size);
}

static ssize_t max_write_buffer_kb_store(struct device *csdev,
                                         struct device_attribute *attr,
                                         const char *buf, size_t count)
{
        unsigned int minor = MINOR(csdev->devt);
        struct comedi_device *dev;
        struct comedi_subdevice *s;
        unsigned int size;
        int err;

        err = kstrtouint(buf, 10, &size);
        if (err)
                return err;
        if (size > (UINT_MAX / 1024))
                return -EINVAL;
        size *= 1024;

        dev = comedi_dev_get_from_minor(minor);
        if (!dev)
                return -ENODEV;

        mutex_lock(&dev->mutex);
        s = comedi_write_subdevice(dev, minor);
        if (s && (s->subdev_flags & SDF_CMD_WRITE) && s->async)
                s->async->max_bufsize = size;
        else
                err = -EINVAL;
        mutex_unlock(&dev->mutex);

        comedi_dev_put(dev);
        return err ? err : count;
}
static DEVICE_ATTR_RW(max_write_buffer_kb);

static ssize_t write_buffer_kb_show(struct device *csdev,
                                    struct device_attribute *attr, char *buf)
{
        unsigned int minor = MINOR(csdev->devt);
        struct comedi_device *dev;
        struct comedi_subdevice *s;
        unsigned int size = 0;

        dev = comedi_dev_get_from_minor(minor);
        if (!dev)
                return -ENODEV;

        mutex_lock(&dev->mutex);
        s = comedi_write_subdevice(dev, minor);
        if (s && (s->subdev_flags & SDF_CMD_WRITE) && s->async)
                size = s->async->prealloc_bufsz / 1024;
        mutex_unlock(&dev->mutex);

        comedi_dev_put(dev);
        return snprintf(buf, PAGE_SIZE, "%i\n", size);
}

static ssize_t write_buffer_kb_store(struct device *csdev,
                                     struct device_attribute *attr,
                                     const char *buf, size_t count)
{
        unsigned int minor = MINOR(csdev->devt);
        struct comedi_device *dev;
        struct comedi_subdevice *s;
        unsigned int size;
        int err;

        err = kstrtouint(buf, 10, &size);
        if (err)
                return err;
        if (size > (UINT_MAX / 1024))
                return -EINVAL;
        size *= 1024;

        dev = comedi_dev_get_from_minor(minor);
        if (!dev)
                return -ENODEV;

        mutex_lock(&dev->mutex);
        s = comedi_write_subdevice(dev, minor);
        if (s && (s->subdev_flags & SDF_CMD_WRITE) && s->async)
                err = resize_async_buffer(dev, s, s->async, size);
        else
                err = -EINVAL;
        mutex_unlock(&dev->mutex);

        comedi_dev_put(dev);
        return err ? err : count;
}
static DEVICE_ATTR_RW(write_buffer_kb);

static struct attribute *comedi_dev_attrs[] = {
        &dev_attr_max_read_buffer_kb.attr,
        &dev_attr_read_buffer_kb.attr,
        &dev_attr_max_write_buffer_kb.attr,
        &dev_attr_write_buffer_kb.attr,
        NULL,
};
ATTRIBUTE_GROUPS(comedi_dev);

static void comedi_set_subdevice_runflags(struct comedi_subdevice *s,
                                          unsigned mask, unsigned bits)
{
        unsigned long flags;

        spin_lock_irqsave(&s->spin_lock, flags);
        s->runflags &= ~mask;
        s->runflags |= (bits & mask);
        spin_unlock_irqrestore(&s->spin_lock, flags);
}

static unsigned comedi_get_subdevice_runflags(struct comedi_subdevice *s)
{
        unsigned long flags;
        unsigned runflags;

        spin_lock_irqsave(&s->spin_lock, flags);
        runflags = s->runflags;
        spin_unlock_irqrestore(&s->spin_lock, flags);
        return runflags;
}

bool comedi_is_subdevice_running(struct comedi_subdevice *s)
{
        unsigned runflags = comedi_get_subdevice_runflags(s);

        return (runflags & SRF_RUNNING) ? true : false;
}
EXPORT_SYMBOL_GPL(comedi_is_subdevice_running);

static bool comedi_is_subdevice_in_error(struct comedi_subdevice *s)
{
        unsigned runflags = comedi_get_subdevice_runflags(s);

        return (runflags & SRF_ERROR) ? true : false;
}

static bool comedi_is_subdevice_idle(struct comedi_subdevice *s)
{
        unsigned runflags = comedi_get_subdevice_runflags(s);

        return (runflags & (SRF_ERROR | SRF_RUNNING)) ? false : true;
}

/**
 * comedi_alloc_spriv() - Allocate memory for the subdevice private data.
 * @s: comedi_subdevice struct
 * @size: size of the memory to allocate
 *
 * This also sets the subdevice runflags to allow the core to automatically
 * free the private data during the detach.
 */
void *comedi_alloc_spriv(struct comedi_subdevice *s, size_t size)
{
        s->private = kzalloc(size, GFP_KERNEL);
        if (s->private)
                s->runflags |= SRF_FREE_SPRIV;
        return s->private;
}
EXPORT_SYMBOL_GPL(comedi_alloc_spriv);

/*
   This function restores a subdevice to an idle state.
 */
static void do_become_nonbusy(struct comedi_device *dev,
                              struct comedi_subdevice *s)
{
        struct comedi_async *async = s->async;

        comedi_set_subdevice_runflags(s, SRF_RUNNING, 0);
        if (async) {
                comedi_buf_reset(async);
                async->inttrig = NULL;
                kfree(async->cmd.chanlist);
                async->cmd.chanlist = NULL;
                s->busy = NULL;
                wake_up_interruptible_all(&s->async->wait_head);
        } else {
                dev_err(dev->class_dev,
                        "BUG: (?) do_become_nonbusy called with async=NULL\n");
                s->busy = NULL;
        }
}

static int do_cancel(struct comedi_device *dev, struct comedi_subdevice *s)
{
        int ret = 0;

        if (comedi_is_subdevice_running(s) && s->cancel)
                ret = s->cancel(dev, s);

        do_become_nonbusy(dev, s);

        return ret;
}

void comedi_device_cancel_all(struct comedi_device *dev)
{
        struct comedi_subdevice *s;
        int i;

        if (!dev->attached)
                return;

        for (i = 0; i < dev->n_subdevices; i++) {
                s = &dev->subdevices[i];
                if (s->async)
                        do_cancel(dev, s);
        }
}

static int is_device_busy(struct comedi_device *dev)
{
        struct comedi_subdevice *s;
        int i;

        if (!dev->attached)
                return 0;

        for (i = 0; i < dev->n_subdevices; i++) {
                s = &dev->subdevices[i];
                if (s->busy)
                        return 1;
                if (s->async && comedi_buf_is_mmapped(s->async))
                        return 1;
        }

        return 0;
}

/*
        COMEDI_DEVCONFIG
        device config ioctl

        arg:
                pointer to devconfig structure

        reads:
                devconfig structure at arg

        writes:
                none
*/
static int do_devconfig_ioctl(struct comedi_device *dev,
                              struct comedi_devconfig __user *arg)
{
        struct comedi_devconfig it;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        if (arg == NULL) {
                if (is_device_busy(dev))
                        return -EBUSY;
                if (dev->attached) {
                        struct module *driver_module = dev->driver->module;
                        comedi_device_detach(dev);
                        module_put(driver_module);
                }
                return 0;
        }

        if (copy_from_user(&it, arg, sizeof(it)))
                return -EFAULT;

        it.board_name[COMEDI_NAMELEN - 1] = 0;

        if (it.options[COMEDI_DEVCONF_AUX_DATA_LENGTH]) {
                dev_warn(dev->class_dev,
                         "comedi_config --init_data is deprecated\n");
                return -EINVAL;
        }

        if (dev->minor >= comedi_num_legacy_minors)
                /* don't re-use dynamically allocated comedi devices */
                return -EBUSY;

        /* This increments the driver module count on success. */
        return comedi_device_attach(dev, &it);
}

/*
        COMEDI_BUFCONFIG
        buffer configuration ioctl

        arg:
                pointer to bufconfig structure

        reads:
                bufconfig at arg

        writes:
                modified bufconfig at arg

*/
static int do_bufconfig_ioctl(struct comedi_device *dev,
                              struct comedi_bufconfig __user *arg)
{
        struct comedi_bufconfig bc;
        struct comedi_async *async;
        struct comedi_subdevice *s;
        int retval = 0;

        if (copy_from_user(&bc, arg, sizeof(bc)))
                return -EFAULT;

        if (bc.subdevice >= dev->n_subdevices)
                return -EINVAL;

        s = &dev->subdevices[bc.subdevice];
        async = s->async;

        if (!async) {
                dev_dbg(dev->class_dev,
                        "subdevice does not have async capability\n");
                bc.size = 0;
                bc.maximum_size = 0;
                goto copyback;
        }

        if (bc.maximum_size) {
                if (!capable(CAP_SYS_ADMIN))
                        return -EPERM;

                async->max_bufsize = bc.maximum_size;
        }

        if (bc.size) {
                retval = resize_async_buffer(dev, s, async, bc.size);
                if (retval < 0)
                        return retval;
        }

        bc.size = async->prealloc_bufsz;
        bc.maximum_size = async->max_bufsize;

copyback:
        if (copy_to_user(arg, &bc, sizeof(bc)))
                return -EFAULT;

        return 0;
}

/*
        COMEDI_DEVINFO
        device info ioctl

        arg:
                pointer to devinfo structure

        reads:
                none

        writes:
                devinfo structure

*/
static int do_devinfo_ioctl(struct comedi_device *dev,
                            struct comedi_devinfo __user *arg,
                            struct file *file)
{
        const unsigned minor = iminor(file_inode(file));
        struct comedi_subdevice *s;
        struct comedi_devinfo devinfo;

        memset(&devinfo, 0, sizeof(devinfo));

        /* fill devinfo structure */
        devinfo.version_code = COMEDI_VERSION_CODE;
        devinfo.n_subdevs = dev->n_subdevices;
        strlcpy(devinfo.driver_name, dev->driver->driver_name, COMEDI_NAMELEN);
        strlcpy(devinfo.board_name, dev->board_name, COMEDI_NAMELEN);

        s = comedi_read_subdevice(dev, minor);
        if (s)
                devinfo.read_subdevice = s->index;
        else
                devinfo.read_subdevice = -1;

        s = comedi_write_subdevice(dev, minor);
        if (s)
                devinfo.write_subdevice = s->index;
        else
                devinfo.write_subdevice = -1;

        if (copy_to_user(arg, &devinfo, sizeof(devinfo)))
                return -EFAULT;

        return 0;
}

/*
        COMEDI_SUBDINFO
        subdevice info ioctl

        arg:
                pointer to array of subdevice info structures

        reads:
                none

        writes:
                array of subdevice info structures at arg

*/
static int do_subdinfo_ioctl(struct comedi_device *dev,
                             struct comedi_subdinfo __user *arg, void *file)
{
        int ret, i;
        struct comedi_subdinfo *tmp, *us;
        struct comedi_subdevice *s;

        tmp = kcalloc(dev->n_subdevices, sizeof(*tmp), GFP_KERNEL);
        if (!tmp)
                return -ENOMEM;

        /* fill subdinfo structs */
        for (i = 0; i < dev->n_subdevices; i++) {
                s = &dev->subdevices[i];
                us = tmp + i;

                us->type = s->type;
                us->n_chan = s->n_chan;
                us->subd_flags = s->subdev_flags;
                if (comedi_is_subdevice_running(s))
                        us->subd_flags |= SDF_RUNNING;
#define TIMER_nanosec 5         /* backwards compatibility */
                us->timer_type = TIMER_nanosec;
                us->len_chanlist = s->len_chanlist;
                us->maxdata = s->maxdata;
                if (s->range_table) {
                        us->range_type =
                            (i << 24) | (0 << 16) | (s->range_table->length);
                } else {
                        us->range_type = 0;     /* XXX */
                }

                if (s->busy)
                        us->subd_flags |= SDF_BUSY;
                if (s->busy == file)
                        us->subd_flags |= SDF_BUSY_OWNER;
                if (s->lock)
                        us->subd_flags |= SDF_LOCKED;
                if (s->lock == file)
                        us->subd_flags |= SDF_LOCK_OWNER;
                if (!s->maxdata && s->maxdata_list)
                        us->subd_flags |= SDF_MAXDATA;
                if (s->range_table_list)
                        us->subd_flags |= SDF_RANGETYPE;
                if (s->do_cmd)
                        us->subd_flags |= SDF_CMD;

                if (s->insn_bits != &insn_inval)
                        us->insn_bits_support = COMEDI_SUPPORTED;
                else
                        us->insn_bits_support = COMEDI_UNSUPPORTED;
        }

        ret = copy_to_user(arg, tmp, dev->n_subdevices * sizeof(*tmp));

        kfree(tmp);

        return ret ? -EFAULT : 0;
}

/*
        COMEDI_CHANINFO
        subdevice info ioctl

        arg:
                pointer to chaninfo structure

        reads:
                chaninfo structure at arg

        writes:
                arrays at elements of chaninfo structure

*/
static int do_chaninfo_ioctl(struct comedi_device *dev,
                             struct comedi_chaninfo __user *arg)
{
        struct comedi_subdevice *s;
        struct comedi_chaninfo it;

        if (copy_from_user(&it, arg, sizeof(it)))
                return -EFAULT;

        if (it.subdev >= dev->n_subdevices)
                return -EINVAL;
        s = &dev->subdevices[it.subdev];

        if (it.maxdata_list) {
                if (s->maxdata || !s->maxdata_list)
                        return -EINVAL;
                if (copy_to_user(it.maxdata_list, s->maxdata_list,
                                 s->n_chan * sizeof(unsigned int)))
                        return -EFAULT;
        }

        if (it.flaglist)
                return -EINVAL; /* flaglist not supported */

        if (it.rangelist) {
                int i;

                if (!s->range_table_list)
                        return -EINVAL;
                for (i = 0; i < s->n_chan; i++) {
                        int x;

                        x = (dev->minor << 28) | (it.subdev << 24) | (i << 16) |
                            (s->range_table_list[i]->length);
                        if (put_user(x, it.rangelist + i))
                                return -EFAULT;
                }
#if 0
                if (copy_to_user(it.rangelist, s->range_type_list,
                                 s->n_chan * sizeof(unsigned int)))
                        return -EFAULT;
#endif
        }

        return 0;
}

 /*
    COMEDI_BUFINFO
    buffer information ioctl

    arg:
    pointer to bufinfo structure

    reads:
    bufinfo at arg

    writes:
    modified bufinfo at arg

  */
static int do_bufinfo_ioctl(struct comedi_device *dev,
                            struct comedi_bufinfo __user *arg, void *file)
{
        struct comedi_bufinfo bi;
        struct comedi_subdevice *s;
        struct comedi_async *async;

        if (copy_from_user(&bi, arg, sizeof(bi)))
                return -EFAULT;

        if (bi.subdevice >= dev->n_subdevices)
                return -EINVAL;

        s = &dev->subdevices[bi.subdevice];

        if (s->lock && s->lock != file)
                return -EACCES;

        async = s->async;

        if (!async) {
                dev_dbg(dev->class_dev,
                        "subdevice does not have async capability\n");
                bi.buf_write_ptr = 0;
                bi.buf_read_ptr = 0;
                bi.buf_write_count = 0;
                bi.buf_read_count = 0;
                bi.bytes_read = 0;
                bi.bytes_written = 0;
                goto copyback;
        }
        if (!s->busy) {
                bi.bytes_read = 0;
                bi.bytes_written = 0;
                goto copyback_position;
        }
        if (s->busy != file)
                return -EACCES;

        if (bi.bytes_read && (s->subdev_flags & SDF_CMD_READ)) {
                bi.bytes_read = comedi_buf_read_alloc(async, bi.bytes_read);
                comedi_buf_read_free(async, bi.bytes_read);

                if (comedi_is_subdevice_idle(s) &&
                    async->buf_write_count == async->buf_read_count) {
                        do_become_nonbusy(dev, s);

                }
        }

        if (bi.bytes_written && (s->subdev_flags & SDF_CMD_WRITE)) {
                bi.bytes_written =
                    comedi_buf_write_alloc(async, bi.bytes_written);
                comedi_buf_write_free(async, bi.bytes_written);
        }

copyback_position:
        bi.buf_write_count = async->buf_write_count;
        bi.buf_write_ptr = async->buf_write_ptr;
        bi.buf_read_count = async->buf_read_count;
        bi.buf_read_ptr = async->buf_read_ptr;

copyback:
        if (copy_to_user(arg, &bi, sizeof(bi)))
                return -EFAULT;

        return 0;
}

static int check_insn_config_length(struct comedi_insn *insn,
                                    unsigned int *data)
{
        if (insn->n < 1)
                return -EINVAL;

        switch (data[0]) {
        case INSN_CONFIG_DIO_OUTPUT:
        case INSN_CONFIG_DIO_INPUT:
        case INSN_CONFIG_DISARM:
        case INSN_CONFIG_RESET:
                if (insn->n == 1)
                        return 0;
                break;
        case INSN_CONFIG_ARM:
        case INSN_CONFIG_DIO_QUERY:
        case INSN_CONFIG_BLOCK_SIZE:
        case INSN_CONFIG_FILTER:
        case INSN_CONFIG_SERIAL_CLOCK:
        case INSN_CONFIG_BIDIRECTIONAL_DATA:
        case INSN_CONFIG_ALT_SOURCE:
        case INSN_CONFIG_SET_COUNTER_MODE:
        case INSN_CONFIG_8254_READ_STATUS:
        case INSN_CONFIG_SET_ROUTING:
        case INSN_CONFIG_GET_ROUTING:
        case INSN_CONFIG_GET_PWM_STATUS:
        case INSN_CONFIG_PWM_SET_PERIOD:
        case INSN_CONFIG_PWM_GET_PERIOD:
                if (insn->n == 2)
                        return 0;
                break;
        case INSN_CONFIG_SET_GATE_SRC:
        case INSN_CONFIG_GET_GATE_SRC:
        case INSN_CONFIG_SET_CLOCK_SRC:
        case INSN_CONFIG_GET_CLOCK_SRC:
        case INSN_CONFIG_SET_OTHER_SRC:
        case INSN_CONFIG_GET_COUNTER_STATUS:
        case INSN_CONFIG_PWM_SET_H_BRIDGE:
        case INSN_CONFIG_PWM_GET_H_BRIDGE:
        case INSN_CONFIG_GET_HARDWARE_BUFFER_SIZE:
                if (insn->n == 3)
                        return 0;
                break;
        case INSN_CONFIG_PWM_OUTPUT:
        case INSN_CONFIG_ANALOG_TRIG:
                if (insn->n == 5)
                        return 0;
                break;
        case INSN_CONFIG_DIGITAL_TRIG:
                if (insn->n == 6)
                        return 0;
                break;
                /* by default we allow the insn since we don't have checks for
                 * all possible cases yet */
        default:
                pr_warn("comedi: No check for data length of config insn id %i is implemented.\n",
                        data[0]);
                pr_warn("comedi: Add a check to %s in %s.\n",
                        __func__, __FILE__);
                pr_warn("comedi: Assuming n=%i is correct.\n", insn->n);
                return 0;
        }
        return -EINVAL;
}

static int parse_insn(struct comedi_device *dev, struct comedi_insn *insn,
                      unsigned int *data, void *file)
{
        struct comedi_subdevice *s;
        int ret = 0;
        int i;

        if (insn->insn & INSN_MASK_SPECIAL) {
                /* a non-subdevice instruction */

                switch (insn->insn) {
                case INSN_GTOD:
                        {
                                struct timeval tv;

                                if (insn->n != 2) {
                                        ret = -EINVAL;
                                        break;
                                }

                                do_gettimeofday(&tv);
                                data[0] = tv.tv_sec;
                                data[1] = tv.tv_usec;
                                ret = 2;

                                break;
                        }
                case INSN_WAIT:
                        if (insn->n != 1 || data[0] >= 100000) {
                                ret = -EINVAL;
                                break;
                        }
                        udelay(data[0] / 1000);
                        ret = 1;
                        break;
                case INSN_INTTRIG:
                        if (insn->n != 1) {
                                ret = -EINVAL;
                                break;
                        }
                        if (insn->subdev >= dev->n_subdevices) {
                                dev_dbg(dev->class_dev,
                                        "%d not usable subdevice\n",
                                        insn->subdev);
                                ret = -EINVAL;
                                break;
                        }
                        s = &dev->subdevices[insn->subdev];
                        if (!s->async) {
                                dev_dbg(dev->class_dev, "no async\n");
                                ret = -EINVAL;
                                break;
                        }
                        if (!s->async->inttrig) {
                                dev_dbg(dev->class_dev, "no inttrig\n");
                                ret = -EAGAIN;
                                break;
                        }
                        ret = s->async->inttrig(dev, s, data[0]);
                        if (ret >= 0)
                                ret = 1;
                        break;
                default:
                        dev_dbg(dev->class_dev, "invalid insn\n");
                        ret = -EINVAL;
                        break;
                }
        } else {
                /* a subdevice instruction */
                unsigned int maxdata;

                if (insn->subdev >= dev->n_subdevices) {
                        dev_dbg(dev->class_dev, "subdevice %d out of range\n",
                                insn->subdev);
                        ret = -EINVAL;
                        goto out;
                }
                s = &dev->subdevices[insn->subdev];

                if (s->type == COMEDI_SUBD_UNUSED) {
                        dev_dbg(dev->class_dev, "%d not usable subdevice\n",
                                insn->subdev);
                        ret = -EIO;
                        goto out;
                }

                /* are we locked? (ioctl lock) */
                if (s->lock && s->lock != file) {
                        dev_dbg(dev->class_dev, "device locked\n");
                        ret = -EACCES;
                        goto out;
                }

                ret = comedi_check_chanlist(s, 1, &insn->chanspec);
                if (ret < 0) {
                        ret = -EINVAL;
                        dev_dbg(dev->class_dev, "bad chanspec\n");
                        goto out;
                }

                if (s->busy) {
                        ret = -EBUSY;
                        goto out;
                }
                /* This looks arbitrary.  It is. */
                s->busy = &parse_insn;
                switch (insn->insn) {
                case INSN_READ:
                        ret = s->insn_read(dev, s, insn, data);
                        break;
                case INSN_WRITE:
                        maxdata = s->maxdata_list
                            ? s->maxdata_list[CR_CHAN(insn->chanspec)]
                            : s->maxdata;
                        for (i = 0; i < insn->n; ++i) {
                                if (data[i] > maxdata) {
                                        ret = -EINVAL;
                                        dev_dbg(dev->class_dev,
                                                "bad data value(s)\n");
                                        break;
                                }
                        }
                        if (ret == 0)
                                ret = s->insn_write(dev, s, insn, data);
                        break;
                case INSN_BITS:
                        if (insn->n != 2) {
                                ret = -EINVAL;
                        } else {
                                /* Most drivers ignore the base channel in
                                 * insn->chanspec.  Fix this here if
                                 * the subdevice has <= 32 channels.  */
                                unsigned int shift;
                                unsigned int orig_mask;

                                orig_mask = data[0];
                                if (s->n_chan <= 32) {
                                        shift = CR_CHAN(insn->chanspec);
                                        if (shift > 0) {
                                                insn->chanspec = 0;
                                                data[0] <<= shift;
                                                data[1] <<= shift;
                                        }
                                } else
                                        shift = 0;
                                ret = s->insn_bits(dev, s, insn, data);
                                data[0] = orig_mask;
                                if (shift > 0)
                                        data[1] >>= shift;
                        }
                        break;
                case INSN_CONFIG:
                        ret = check_insn_config_length(insn, data);
                        if (ret)
                                break;
                        ret = s->insn_config(dev, s, insn, data);
                        break;
                default:
                        ret = -EINVAL;
                        break;
                }

                s->busy = NULL;
        }

out:
        return ret;
}

/*
 *      COMEDI_INSNLIST
 *      synchronous instructions
 *
 *      arg:
 *              pointer to sync cmd structure
 *
 *      reads:
 *              sync cmd struct at arg
 *              instruction list
 *              data (for writes)
 *
 *      writes:
 *              data (for reads)
 */
/* arbitrary limits */
#define MAX_SAMPLES 256
static int do_insnlist_ioctl(struct comedi_device *dev,
                             struct comedi_insnlist __user *arg, void *file)
{
        struct comedi_insnlist insnlist;
        struct comedi_insn *insns = NULL;
        unsigned int *data = NULL;
        int i = 0;
        int ret = 0;

        if (copy_from_user(&insnlist, arg, sizeof(insnlist)))
                return -EFAULT;

        data = kmalloc(sizeof(unsigned int) * MAX_SAMPLES, GFP_KERNEL);
        if (!data) {
                ret = -ENOMEM;
                goto error;
        }

        insns = kcalloc(insnlist.n_insns, sizeof(*insns), GFP_KERNEL);
        if (!insns) {
                ret = -ENOMEM;
                goto error;
        }

        if (copy_from_user(insns, insnlist.insns,
                           sizeof(*insns) * insnlist.n_insns)) {
                dev_dbg(dev->class_dev, "copy_from_user failed\n");
                ret = -EFAULT;
                goto error;
        }

        for (i = 0; i < insnlist.n_insns; i++) {
                if (insns[i].n > MAX_SAMPLES) {
                        dev_dbg(dev->class_dev,
                                "number of samples too large\n");
                        ret = -EINVAL;
                        goto error;
                }
                if (insns[i].insn & INSN_MASK_WRITE) {
                        if (copy_from_user(data, insns[i].data,
                                           insns[i].n * sizeof(unsigned int))) {
                                dev_dbg(dev->class_dev,
                                        "copy_from_user failed\n");
                                ret = -EFAULT;
                                goto error;
                        }
                }
                ret = parse_insn(dev, insns + i, data, file);
                if (ret < 0)
                        goto error;
                if (insns[i].insn & INSN_MASK_READ) {
                        if (copy_to_user(insns[i].data, data,
                                         insns[i].n * sizeof(unsigned int))) {
                                dev_dbg(dev->class_dev,
                                        "copy_to_user failed\n");
                                ret = -EFAULT;
                                goto error;
                        }
                }
                if (need_resched())
                        schedule();
        }

error:
        kfree(insns);
        kfree(data);

        if (ret < 0)
                return ret;
        return i;
}

/*
 *      COMEDI_INSN
 *      synchronous instructions
 *
 *      arg:
 *              pointer to insn
 *
 *      reads:
 *              struct comedi_insn struct at arg
 *              data (for writes)
 *
 *      writes:
 *              data (for reads)
 */
static int do_insn_ioctl(struct comedi_device *dev,
                         struct comedi_insn __user *arg, void *file)
{
        struct comedi_insn insn;
        unsigned int *data = NULL;
        int ret = 0;

        data = kmalloc(sizeof(unsigned int) * MAX_SAMPLES, GFP_KERNEL);
        if (!data) {
                ret = -ENOMEM;
                goto error;
        }

        if (copy_from_user(&insn, arg, sizeof(insn))) {
                ret = -EFAULT;
                goto error;
        }

        /* This is where the behavior of insn and insnlist deviate. */
        if (insn.n > MAX_SAMPLES)
                insn.n = MAX_SAMPLES;
        if (insn.insn & INSN_MASK_WRITE) {
                if (copy_from_user(data,
                                   insn.data,
                                   insn.n * sizeof(unsigned int))) {
                        ret = -EFAULT;
                        goto error;
                }
        }
        ret = parse_insn(dev, &insn, data, file);
        if (ret < 0)
                goto error;
        if (insn.insn & INSN_MASK_READ) {
                if (copy_to_user(insn.data,
                                 data,
                                 insn.n * sizeof(unsigned int))) {
                        ret = -EFAULT;
                        goto error;
                }
        }
        ret = insn.n;

error:
        kfree(data);

        return ret;
}

static int do_cmd_ioctl(struct comedi_device *dev,
                        struct comedi_cmd __user *arg, void *file)
{
        struct comedi_cmd cmd;
        struct comedi_subdevice *s;
        struct comedi_async *async;
        int ret = 0;
        unsigned int __user *user_chanlist;

        if (copy_from_user(&cmd, arg, sizeof(cmd))) {
                dev_dbg(dev->class_dev, "bad cmd address\n");
                return -EFAULT;
        }
        /* save user's chanlist pointer so it can be restored later */
        user_chanlist = (unsigned int __user *)cmd.chanlist;

        if (cmd.subdev >= dev->n_subdevices) {
                dev_dbg(dev->class_dev, "%d no such subdevice\n", cmd.subdev);
                return -ENODEV;
        }

        s = &dev->subdevices[cmd.subdev];
        async = s->async;

        if (s->type == COMEDI_SUBD_UNUSED) {
                dev_dbg(dev->class_dev, "%d not valid subdevice\n", cmd.subdev);
                return -EIO;
        }

        if (!s->do_cmd || !s->do_cmdtest || !s->async) {
                dev_dbg(dev->class_dev,
                        "subdevice %i does not support commands\n", cmd.subdev);
                return -EIO;
        }

        /* are we locked? (ioctl lock) */
        if (s->lock && s->lock != file) {
                dev_dbg(dev->class_dev, "subdevice locked\n");
                return -EACCES;
        }

        /* are we busy? */
        if (s->busy) {
                dev_dbg(dev->class_dev, "subdevice busy\n");
                return -EBUSY;
        }

        /* make sure channel/gain list isn't too long */
        if (cmd.chanlist_len > s->len_chanlist) {
                dev_dbg(dev->class_dev, "channel/gain list too long %u > %d\n",
                        cmd.chanlist_len, s->len_chanlist);
                return -EINVAL;
        }

        /* make sure channel/gain list isn't too short */
        if (cmd.chanlist_len < 1) {
                dev_dbg(dev->class_dev, "channel/gain list too short %u < 1\n",
                        cmd.chanlist_len);
                return -EINVAL;
        }

        async->cmd = cmd;
        async->cmd.data = NULL;
        /* load channel/gain list */
        async->cmd.chanlist = memdup_user(user_chanlist,
                                          async->cmd.chanlist_len * sizeof(int));
        if (IS_ERR(async->cmd.chanlist)) {
                ret = PTR_ERR(async->cmd.chanlist);
                async->cmd.chanlist = NULL;
                dev_dbg(dev->class_dev, "memdup_user failed with code %d\n",
                        ret);
                goto cleanup;
        }

        /* make sure each element in channel/gain list is valid */
        ret = comedi_check_chanlist(s,
                                    async->cmd.chanlist_len,
                                    async->cmd.chanlist);
        if (ret < 0) {
                dev_dbg(dev->class_dev, "bad chanlist\n");
                goto cleanup;
        }

        ret = s->do_cmdtest(dev, s, &async->cmd);

        if (async->cmd.flags & TRIG_BOGUS || ret) {
                dev_dbg(dev->class_dev, "test returned %d\n", ret);
                cmd = async->cmd;
                /* restore chanlist pointer before copying back */
                cmd.chanlist = (unsigned int __force *)user_chanlist;
                cmd.data = NULL;
                if (copy_to_user(arg, &cmd, sizeof(cmd))) {
                        dev_dbg(dev->class_dev, "fault writing cmd\n");
                        ret = -EFAULT;
                        goto cleanup;
                }
                ret = -EAGAIN;
                goto cleanup;
        }

        if (!async->prealloc_bufsz) {
                ret = -ENOMEM;
                dev_dbg(dev->class_dev, "no buffer (?)\n");
                goto cleanup;
        }

        comedi_buf_reset(async);

        async->cb_mask =
            COMEDI_CB_EOA | COMEDI_CB_BLOCK | COMEDI_CB_ERROR |
            COMEDI_CB_OVERFLOW;
        if (async->cmd.flags & TRIG_WAKE_EOS)
                async->cb_mask |= COMEDI_CB_EOS;

        comedi_set_subdevice_runflags(s, SRF_ERROR | SRF_RUNNING, SRF_RUNNING);

        /* set s->busy _after_ setting SRF_RUNNING flag to avoid race with
         * comedi_read() or comedi_write() */
        s->busy = file;
        ret = s->do_cmd(dev, s);
        if (ret == 0)
                return 0;

cleanup:
        do_become_nonbusy(dev, s);

        return ret;
}

/*
        COMEDI_CMDTEST
        command testing ioctl

        arg:
                pointer to cmd structure

        reads:
                cmd structure at arg
                channel/range list

        writes:
                modified cmd structure at arg

*/
static int do_cmdtest_ioctl(struct comedi_device *dev,
                            struct comedi_cmd __user *arg, void *file)
{
        struct comedi_cmd cmd;
        struct comedi_subdevice *s;
        int ret = 0;
        unsigned int *chanlist = NULL;
        unsigned int __user *user_chanlist;

        if (copy_from_user(&cmd, arg, sizeof(cmd))) {
                dev_dbg(dev->class_dev, "bad cmd address\n");
                return -EFAULT;
        }
        /* save user's chanlist pointer so it can be restored later */
        user_chanlist = (unsigned int __user *)cmd.chanlist;

        if (cmd.subdev >= dev->n_subdevices) {
                dev_dbg(dev->class_dev, "%d no such subdevice\n", cmd.subdev);
                return -ENODEV;
        }

        s = &dev->subdevices[cmd.subdev];
        if (s->type == COMEDI_SUBD_UNUSED) {
                dev_dbg(dev->class_dev, "%d not valid subdevice\n", cmd.subdev);
                return -EIO;
        }

        if (!s->do_cmd || !s->do_cmdtest) {
                dev_dbg(dev->class_dev,
                        "subdevice %i does not support commands\n", cmd.subdev);
                return -EIO;
        }

        /* make sure channel/gain list isn't too long */
        if (cmd.chanlist_len > s->len_chanlist) {
                dev_dbg(dev->class_dev, "channel/gain list too long %d > %d\n",
                        cmd.chanlist_len, s->len_chanlist);
                ret = -EINVAL;
                goto cleanup;
        }

        /* load channel/gain list */
        if (cmd.chanlist) {
                chanlist = memdup_user(user_chanlist,
                                       cmd.chanlist_len * sizeof(int));
                if (IS_ERR(chanlist)) {
                        ret = PTR_ERR(chanlist);
                        chanlist = NULL;
                        dev_dbg(dev->class_dev,
                                "memdup_user exited with code %d", ret);
                        goto cleanup;
                }

                /* make sure each element in channel/gain list is valid */
                ret = comedi_check_chanlist(s, cmd.chanlist_len, chanlist);
                if (ret < 0) {
                        dev_dbg(dev->class_dev, "bad chanlist\n");
                        goto cleanup;
                }

                cmd.chanlist = chanlist;
        }

        ret = s->do_cmdtest(dev, s, &cmd);

        /* restore chanlist pointer before copying back */
        cmd.chanlist = (unsigned int __force *)user_chanlist;

        if (copy_to_user(arg, &cmd, sizeof(cmd))) {
                dev_dbg(dev->class_dev, "bad cmd address\n");
                ret = -EFAULT;
                goto cleanup;
        }
cleanup:
        kfree(chanlist);

        return ret;
}

/*
        COMEDI_LOCK
        lock subdevice

        arg:
                subdevice number

        reads:
                none

        writes:
                none

*/

static int do_lock_ioctl(struct comedi_device *dev, unsigned int arg,
                         void *file)
{
        int ret = 0;
        unsigned long flags;
        struct comedi_subdevice *s;

        if (arg >= dev->n_subdevices)
                return -EINVAL;
        s = &dev->subdevices[arg];

        spin_lock_irqsave(&s->spin_lock, flags);
        if (s->busy || s->lock)
                ret = -EBUSY;
        else
                s->lock = file;
        spin_unlock_irqrestore(&s->spin_lock, flags);

#if 0
        if (ret < 0)
                return ret;

        if (s->lock_f)
                ret = s->lock_f(dev, s);
#endif

        return ret;
}

/*
        COMEDI_UNLOCK
        unlock subdevice

        arg:
                subdevice number

        reads:
                none

        writes:
                none

        This function isn't protected by the semaphore, since
        we already own the lock.
*/
static int do_unlock_ioctl(struct comedi_device *dev, unsigned int arg,
                           void *file)
{
        struct comedi_subdevice *s;

        if (arg >= dev->n_subdevices)
                return -EINVAL;
        s = &dev->subdevices[arg];

        if (s->busy)
                return -EBUSY;

        if (s->lock && s->lock != file)
                return -EACCES;

        if (s->lock == file) {
#if 0
                if (s->unlock)
                        s->unlock(dev, s);
#endif

                s->lock = NULL;
        }

        return 0;
}

/*
        COMEDI_CANCEL
        cancel acquisition ioctl

        arg:
                subdevice number

        reads:
                nothing

        writes:
                nothing

*/
static int do_cancel_ioctl(struct comedi_device *dev, unsigned int arg,
                           void *file)
{
        struct comedi_subdevice *s;
        int ret;

        if (arg >= dev->n_subdevices)
                return -EINVAL;
        s = &dev->subdevices[arg];
        if (s->async == NULL)
                return -EINVAL;

        if (s->lock && s->lock != file)
                return -EACCES;

        if (!s->busy)
                return 0;

        if (s->busy != file)
                return -EBUSY;

        ret = do_cancel(dev, s);

        return ret;
}

/*
        COMEDI_POLL ioctl
        instructs driver to synchronize buffers

        arg:
                subdevice number

        reads:
                nothing

        writes:
                nothing

*/
static int do_poll_ioctl(struct comedi_device *dev, unsigned int arg,
                         void *file)
{
        struct comedi_subdevice *s;

        if (arg >= dev->n_subdevices)
                return -EINVAL;
        s = &dev->subdevices[arg];

        if (s->lock && s->lock != file)
                return -EACCES;

        if (!s->busy)
                return 0;

        if (s->busy != file)
                return -EBUSY;

        if (s->poll)
                return s->poll(dev, s);

        return -EINVAL;
}

static long comedi_unlocked_ioctl(struct file *file, unsigned int cmd,
                                  unsigned long arg)
{
        const unsigned minor = iminor(file_inode(file));
        struct comedi_device *dev = file->private_data;
        int rc;

        mutex_lock(&dev->mutex);

        /* Device config is special, because it must work on
         * an unconfigured device. */
        if (cmd == COMEDI_DEVCONFIG) {
                if (minor >= COMEDI_NUM_BOARD_MINORS) {
                        /* Device config not appropriate on non-board minors. */
                        rc = -ENOTTY;
                        goto done;
                }
                rc = do_devconfig_ioctl(dev,
                                        (struct comedi_devconfig __user *)arg);
                if (rc == 0) {
                        if (arg == 0 &&
                            dev->minor >= comedi_num_legacy_minors) {
                                /* Successfully unconfigured a dynamically
                                 * allocated device.  Try and remove it. */
                                if (comedi_clear_board_dev(dev)) {
                                        mutex_unlock(&dev->mutex);
                                        comedi_free_board_dev(dev);
                                        return rc;
                                }
                        }
                }
                goto done;
        }

        if (!dev->attached) {
                dev_dbg(dev->class_dev, "no driver attached\n");
                rc = -ENODEV;
                goto done;
        }

        switch (cmd) {
        case COMEDI_BUFCONFIG:
                rc = do_bufconfig_ioctl(dev,
                                        (struct comedi_bufconfig __user *)arg);
                break;
        case COMEDI_DEVINFO:
                rc = do_devinfo_ioctl(dev, (struct comedi_devinfo __user *)arg,
                                      file);
                break;
        case COMEDI_SUBDINFO:
                rc = do_subdinfo_ioctl(dev,
                                       (struct comedi_subdinfo __user *)arg,
                                       file);
                break;
        case COMEDI_CHANINFO:
                rc = do_chaninfo_ioctl(dev, (void __user *)arg);
                break;
        case COMEDI_RANGEINFO:
                rc = do_rangeinfo_ioctl(dev, (void __user *)arg);
                break;
        case COMEDI_BUFINFO:
                rc = do_bufinfo_ioctl(dev,
                                      (struct comedi_bufinfo __user *)arg,
                                      file);
                break;
        case COMEDI_LOCK:
                rc = do_lock_ioctl(dev, arg, file);
                break;
        case COMEDI_UNLOCK:
                rc = do_unlock_ioctl(dev, arg, file);
                break;
        case COMEDI_CANCEL:
                rc = do_cancel_ioctl(dev, arg, file);
                break;
        case COMEDI_CMD:
                rc = do_cmd_ioctl(dev, (struct comedi_cmd __user *)arg, file);
                break;
        case COMEDI_CMDTEST:
                rc = do_cmdtest_ioctl(dev, (struct comedi_cmd __user *)arg,
                                      file);
                break;
        case COMEDI_INSNLIST:
                rc = do_insnlist_ioctl(dev,
                                       (struct comedi_insnlist __user *)arg,
                                       file);
                break;
        case COMEDI_INSN:
                rc = do_insn_ioctl(dev, (struct comedi_insn __user *)arg,
                                   file);
                break;
        case COMEDI_POLL:
                rc = do_poll_ioctl(dev, arg, file);
                break;
        default:
                rc = -ENOTTY;
                break;
        }

done:
        mutex_unlock(&dev->mutex);
        return rc;
}

static void comedi_vm_open(struct vm_area_struct *area)
{
        struct comedi_buf_map *bm;

        bm = area->vm_private_data;
        comedi_buf_map_get(bm);
}

static void comedi_vm_close(struct vm_area_struct *area)
{
        struct comedi_buf_map *bm;

        bm = area->vm_private_data;
        comedi_buf_map_put(bm);
}

static struct vm_operations_struct comedi_vm_ops = {
        .open = comedi_vm_open,
        .close = comedi_vm_close,
};

static int comedi_mmap(struct file *file, struct vm_area_struct *vma)
{
        const unsigned minor = iminor(file_inode(file));
        struct comedi_device *dev = file->private_data;
        struct comedi_subdevice *s;
        struct comedi_async *async;
        struct comedi_buf_map *bm;
        unsigned long start = vma->vm_start;
        unsigned long size;
        int n_pages;
        int i;
        int retval;

        mutex_lock(&dev->mutex);

        if (!dev->attached) {
                dev_dbg(dev->class_dev, "no driver attached\n");
                retval = -ENODEV;
                goto done;
        }

        if (vma->vm_flags & VM_WRITE)
                s = comedi_write_subdevice(dev, minor);
        else
                s = comedi_read_subdevice(dev, minor);
        if (!s) {
                retval = -EINVAL;
                goto done;
        }

        async = s->async;
        if (!async) {
                retval = -EINVAL;
                goto done;
        }

        if (vma->vm_pgoff != 0) {
                dev_dbg(dev->class_dev, "mmap() offset must be 0.\n");
                retval = -EINVAL;
                goto done;
        }

        size = vma->vm_end - vma->vm_start;
        if (size > async->prealloc_bufsz) {
                retval = -EFAULT;
                goto done;
        }
        if (size & (~PAGE_MASK)) {
                retval = -EFAULT;
                goto done;
        }

        n_pages = size >> PAGE_SHIFT;
        bm = async->buf_map;
        if (!bm || n_pages > bm->n_pages) {
                retval = -EINVAL;
                goto done;
        }
        for (i = 0; i < n_pages; ++i) {
                struct comedi_buf_page *buf = &bm->page_list[i];

                if (remap_pfn_range(vma, start,
                                    page_to_pfn(virt_to_page(buf->virt_addr)),
                                    PAGE_SIZE, PAGE_SHARED)) {
                        retval = -EAGAIN;
                        goto done;
                }
                start += PAGE_SIZE;
        }

        vma->vm_ops = &comedi_vm_ops;
        vma->vm_private_data = bm;

        vma->vm_ops->open(vma);

        retval = 0;
done:
        mutex_unlock(&dev->mutex);
        return retval;
}

static unsigned int comedi_poll(struct file *file, poll_table *wait)
{
        unsigned int mask = 0;
        const unsigned minor = iminor(file_inode(file));
        struct comedi_device *dev = file->private_data;
        struct comedi_subdevice *s;

        mutex_lock(&dev->mutex);

        if (!dev->attached) {
                dev_dbg(dev->class_dev, "no driver attached\n");
                goto done;
        }

        s = comedi_read_subdevice(dev, minor);
        if (s && s->async) {
                poll_wait(file, &s->async->wait_head, wait);
                if (!s->busy || !comedi_is_subdevice_running(s) ||
                    comedi_buf_read_n_available(s->async) > 0)
                        mask |= POLLIN | POLLRDNORM;
        }

        s = comedi_write_subdevice(dev, minor);
        if (s && s->async) {
                unsigned int bps = bytes_per_sample(s->async->subdevice);

                poll_wait(file, &s->async->wait_head, wait);
                comedi_buf_write_alloc(s->async, s->async->prealloc_bufsz);
                if (!s->busy || !comedi_is_subdevice_running(s) ||
                    comedi_buf_write_n_allocated(s->async) >= bps)
                        mask |= POLLOUT | POLLWRNORM;
        }

done:
        mutex_unlock(&dev->mutex);
        return mask;
}

static ssize_t comedi_write(struct file *file, const char __user *buf,
                            size_t nbytes, loff_t *offset)
{
        struct comedi_subdevice *s;
        struct comedi_async *async;
        int n, m, count = 0, retval = 0;
        DECLARE_WAITQUEUE(wait, current);
        const unsigned minor = iminor(file_inode(file));
        struct comedi_device *dev = file->private_data;
        bool on_wait_queue = false;
        bool attach_locked;
        unsigned int old_detach_count;

        /* Protect against device detachment during operation. */
        down_read(&dev->attach_lock);
        attach_locked = true;
        old_detach_count = dev->detach_count;

        if (!dev->attached) {
                dev_dbg(dev->class_dev, "no driver attached\n");
                retval = -ENODEV;
                goto out;
        }

        s = comedi_write_subdevice(dev, minor);
        if (!s || !s->async) {
                retval = -EIO;
                goto out;
        }

        async = s->async;

        if (!s->busy || !nbytes)
                goto out;
        if (s->busy != file) {
                retval = -EACCES;
                goto out;
        }

        add_wait_queue(&async->wait_head, &wait);
        on_wait_queue = true;
        while (nbytes > 0 && !retval) {
                set_current_state(TASK_INTERRUPTIBLE);

                if (!comedi_is_subdevice_running(s)) {
                        if (count == 0) {
                                struct comedi_subdevice *new_s;

                                if (comedi_is_subdevice_in_error(s))
                                        retval = -EPIPE;
                                else
                                        retval = 0;
                                /*
                                 * To avoid deadlock, cannot acquire dev->mutex
                                 * while dev->attach_lock is held.  Need to
                                 * remove task from the async wait queue before
                                 * releasing dev->attach_lock, as it might not
                                 * be valid afterwards.
                                 */
                                remove_wait_queue(&async->wait_head, &wait);
                                on_wait_queue = false;
                                up_read(&dev->attach_lock);
                                attach_locked = false;
                                mutex_lock(&dev->mutex);
                                /*
                                 * Become non-busy unless things have changed
                                 * behind our back.  Checking dev->detach_count
                                 * is unchanged ought to be sufficient (unless
                                 * there have been 2**32 detaches in the
                                 * meantime!), but check the subdevice pointer
                                 * as well just in case.
                                 */
                                new_s = comedi_write_subdevice(dev, minor);
                                if (dev->attached &&
                                    old_detach_count == dev->detach_count &&
                                    s == new_s && new_s->async == async)
                                        do_become_nonbusy(dev, s);
                                mutex_unlock(&dev->mutex);
                        }
                        break;
                }

                n = nbytes;

                m = n;
                if (async->buf_write_ptr + m > async->prealloc_bufsz)
                        m = async->prealloc_bufsz - async->buf_write_ptr;
                comedi_buf_write_alloc(async, async->prealloc_bufsz);
                if (m > comedi_buf_write_n_allocated(async))
                        m = comedi_buf_write_n_allocated(async);
                if (m < n)
                        n = m;

                if (n == 0) {
                        if (file->f_flags & O_NONBLOCK) {
                                retval = -EAGAIN;
                                break;
                        }
                        schedule();
                        if (signal_pending(current)) {
                                retval = -ERESTARTSYS;
                                break;
                        }
                        if (!s->busy)
                                break;
                        if (s->busy != file) {
                                retval = -EACCES;
                                break;
                        }
                        continue;
                }

                m = copy_from_user(async->prealloc_buf + async->buf_write_ptr,
                                   buf, n);
                if (m) {
                        n -= m;
                        retval = -EFAULT;
                }
                comedi_buf_write_free(async, n);

                count += n;
                nbytes -= n;

                buf += n;
                break;          /* makes device work like a pipe */
        }
out:
        if (on_wait_queue)
                remove_wait_queue(&async->wait_head, &wait);
        set_current_state(TASK_RUNNING);
        if (attach_locked)
                up_read(&dev->attach_lock);

        return count ? count : retval;
}

static ssize_t comedi_read(struct file *file, char __user *buf, size_t nbytes,
                                loff_t *offset)
{
        struct comedi_subdevice *s;
        struct comedi_async *async;
        int n, m, count = 0, retval = 0;
        DECLARE_WAITQUEUE(wait, current);
        const unsigned minor = iminor(file_inode(file));
        struct comedi_device *dev = file->private_data;
        unsigned int old_detach_count;
        bool become_nonbusy = false;
        bool attach_locked;

        /* Protect against device detachment during operation. */
        down_read(&dev->attach_lock);
        attach_locked = true;
        old_detach_count = dev->detach_count;

        if (!dev->attached) {
                dev_dbg(dev->class_dev, "no driver attached\n");
                retval = -ENODEV;
                goto out;
        }

        s = comedi_read_subdevice(dev, minor);
        if (!s || !s->async) {
                retval = -EIO;
                goto out;
        }

        async = s->async;
        if (!s->busy || !nbytes)
                goto out;
        if (s->busy != file) {
                retval = -EACCES;
                goto out;
        }

        add_wait_queue(&async->wait_head, &wait);
        while (nbytes > 0 && !retval) {
                set_current_state(TASK_INTERRUPTIBLE);

                n = nbytes;

                m = comedi_buf_read_n_available(async);
                /* printk("%d available\n",m); */
                if (async->buf_read_ptr + m > async->prealloc_bufsz)
                        m = async->prealloc_bufsz - async->buf_read_ptr;
                /* printk("%d contiguous\n",m); */
                if (m < n)
                        n = m;

                if (n == 0) {
                        if (!comedi_is_subdevice_running(s)) {
                                if (comedi_is_subdevice_in_error(s))
                                        retval = -EPIPE;
                                else
                                        retval = 0;
                                become_nonbusy = true;
                                break;
                        }
                        if (file->f_flags & O_NONBLOCK) {
                                retval = -EAGAIN;
                                break;
                        }
                        schedule();
                        if (signal_pending(current)) {
                                retval = -ERESTARTSYS;
                                break;
                        }
                        if (!s->busy) {
                                retval = 0;
                                break;
                        }
                        if (s->busy != file) {
                                retval = -EACCES;
                                break;
                        }
                        continue;
                }
                m = copy_to_user(buf, async->prealloc_buf +
                                 async->buf_read_ptr, n);
                if (m) {
                        n -= m;
                        retval = -EFAULT;
                }

                comedi_buf_read_alloc(async, n);
                comedi_buf_read_free(async, n);

                count += n;
                nbytes -= n;

                buf += n;
                break;          /* makes device work like a pipe */
        }
        remove_wait_queue(&async->wait_head, &wait);
        set_current_state(TASK_RUNNING);
        if (become_nonbusy || comedi_is_subdevice_idle(s)) {
                struct comedi_subdevice *new_s;

                /*
                 * To avoid deadlock, cannot acquire dev->mutex
                 * while dev->attach_lock is held.
                 */
                up_read(&dev->attach_lock);
                attach_locked = false;
                mutex_lock(&dev->mutex);
                /*
                 * Check device hasn't become detached behind our back.
                 * Checking dev->detach_count is unchanged ought to be
                 * sufficient (unless there have been 2**32 detaches in the
                 * meantime!), but check the subdevice pointer as well just in
                 * case.
                 */
                new_s = comedi_read_subdevice(dev, minor);
                if (dev->attached && old_detach_count == dev->detach_count &&
                    s == new_s && new_s->async == async) {
                        if (become_nonbusy ||
                            async->buf_read_count - async->buf_write_count == 0)
                                do_become_nonbusy(dev, s);
                }
                mutex_unlock(&dev->mutex);
        }
out:
        if (attach_locked)
                up_read(&dev->attach_lock);

        return count ? count : retval;
}

static int comedi_open(struct inode *inode, struct file *file)
{
        const unsigned minor = iminor(inode);
        struct comedi_device *dev = comedi_dev_get_from_minor(minor);
        int rc;

        if (!dev) {
                pr_debug("invalid minor number\n");
                return -ENODEV;
        }

        /* This is slightly hacky, but we want module autoloading
         * to work for root.
         * case: user opens device, attached -> ok
         * case: user opens device, unattached, !in_request_module -> autoload
         * case: user opens device, unattached, in_request_module -> fail
         * case: root opens device, attached -> ok
         * case: root opens device, unattached, in_request_module -> ok
         *   (typically called from modprobe)
         * case: root opens device, unattached, !in_request_module -> autoload
         *
         * The last could be changed to "-> ok", which would deny root
         * autoloading.
         */
        mutex_lock(&dev->mutex);
        if (dev->attached)
                goto ok;
        if (!capable(CAP_NET_ADMIN) && dev->in_request_module) {
                dev_dbg(dev->class_dev, "in request module\n");
                rc = -ENODEV;
                goto out;
        }
        if (capable(CAP_NET_ADMIN) && dev->in_request_module)
                goto ok;

        dev->in_request_module = true;

#ifdef CONFIG_KMOD
        mutex_unlock(&dev->mutex);
        request_module("char-major-%i-%i", COMEDI_MAJOR, dev->minor);
        mutex_lock(&dev->mutex);
#endif

        dev->in_request_module = false;

        if (!dev->attached && !capable(CAP_NET_ADMIN)) {
                dev_dbg(dev->class_dev, "not attached and not CAP_NET_ADMIN\n");
                rc = -ENODEV;
                goto out;
        }
ok:
        if (dev->attached && dev->use_count == 0) {
                if (!try_module_get(dev->driver->module)) {
                        rc = -ENOSYS;
                        goto out;
                }
                if (dev->open) {
                        rc = dev->open(dev);
                        if (rc < 0) {
                                module_put(dev->driver->module);
                                goto out;
                        }
                }
        }

        dev->use_count++;
        file->private_data = dev;
        rc = 0;

out:
        mutex_unlock(&dev->mutex);
        if (rc)
                comedi_dev_put(dev);
        return rc;
}

static int comedi_fasync(int fd, struct file *file, int on)
{
        struct comedi_device *dev = file->private_data;

        return fasync_helper(fd, file, on, &dev->async_queue);
}

static int comedi_close(struct inode *inode, struct file *file)
{
        struct comedi_device *dev = file->private_data;
        struct comedi_subdevice *s = NULL;
        int i;

        mutex_lock(&dev->mutex);

        if (dev->subdevices) {
                for (i = 0; i < dev->n_subdevices; i++) {
                        s = &dev->subdevices[i];

                        if (s->busy == file)
                                do_cancel(dev, s);
                        if (s->lock == file)
                                s->lock = NULL;
                }
        }
        if (dev->attached && dev->use_count == 1) {
                if (dev->close)
                        dev->close(dev);
                module_put(dev->driver->module);
        }

        dev->use_count--;

        mutex_unlock(&dev->mutex);
        comedi_dev_put(dev);

        return 0;
}

static const struct file_operations comedi_fops = {
        .owner = THIS_MODULE,
        .unlocked_ioctl = comedi_unlocked_ioctl,
        .compat_ioctl = comedi_compat_ioctl,
        .open = comedi_open,
        .release = comedi_close,
        .read = comedi_read,
        .write = comedi_write,
        .mmap = comedi_mmap,
        .poll = comedi_poll,
        .fasync = comedi_fasync,
        .llseek = noop_llseek,
};

void comedi_error(const struct comedi_device *dev, const char *s)
{
        dev_err(dev->class_dev, "%s: %s\n", dev->driver->driver_name, s);
}
EXPORT_SYMBOL_GPL(comedi_error);

void comedi_event(struct comedi_device *dev, struct comedi_subdevice *s)
{
        struct comedi_async *async = s->async;
        unsigned runflags = 0;
        unsigned runflags_mask = 0;

        if (!comedi_is_subdevice_running(s))
                return;

        if (s->
            async->events & (COMEDI_CB_EOA | COMEDI_CB_ERROR |
                             COMEDI_CB_OVERFLOW)) {
                runflags_mask |= SRF_RUNNING;
        }
        /* remember if an error event has occurred, so an error
         * can be returned the next time the user does a read() */
        if (s->async->events & (COMEDI_CB_ERROR | COMEDI_CB_OVERFLOW)) {
                runflags_mask |= SRF_ERROR;
                runflags |= SRF_ERROR;
        }
        if (runflags_mask) {
                /*sets SRF_ERROR and SRF_RUNNING together atomically */
                comedi_set_subdevice_runflags(s, runflags_mask, runflags);
        }

        if (async->cb_mask & s->async->events) {
                wake_up_interruptible(&async->wait_head);
                if (s->subdev_flags & SDF_CMD_READ)
                        kill_fasync(&dev->async_queue, SIGIO, POLL_IN);
                if (s->subdev_flags & SDF_CMD_WRITE)
                        kill_fasync(&dev->async_queue, SIGIO, POLL_OUT);
        }
        s->async->events = 0;
}
EXPORT_SYMBOL_GPL(comedi_event);

/* Note: the ->mutex is pre-locked on successful return */
struct comedi_device *comedi_alloc_board_minor(struct device *hardware_device)
{
        struct comedi_device *dev;
        struct device *csdev;
        unsigned i;

        dev = kzalloc(sizeof(struct comedi_device), GFP_KERNEL);
        if (dev == NULL)
                return ERR_PTR(-ENOMEM);
        comedi_device_init(dev);
        comedi_set_hw_dev(dev, hardware_device);
        mutex_lock(&dev->mutex);
        mutex_lock(&comedi_board_minor_table_lock);
        for (i = hardware_device ? comedi_num_legacy_minors : 0;
             i < COMEDI_NUM_BOARD_MINORS; ++i) {
                if (comedi_board_minor_table[i] == NULL) {
                        comedi_board_minor_table[i] = dev;
                        break;
                }
        }
        mutex_unlock(&comedi_board_minor_table_lock);
        if (i == COMEDI_NUM_BOARD_MINORS) {
                mutex_unlock(&dev->mutex);
                comedi_device_cleanup(dev);
                comedi_dev_put(dev);
                pr_err("comedi: error: ran out of minor numbers for board device files.\n");
                return ERR_PTR(-EBUSY);
        }
        dev->minor = i;
        csdev = device_create(comedi_class, hardware_device,
                              MKDEV(COMEDI_MAJOR, i), NULL, "comedi%i", i);
        if (!IS_ERR(csdev))
                dev->class_dev = get_device(csdev);

        /* Note: dev->mutex needs to be unlocked by the caller. */
        return dev;
}

static void comedi_free_board_minor(unsigned minor)
{
        BUG_ON(minor >= COMEDI_NUM_BOARD_MINORS);
        comedi_free_board_dev(comedi_clear_board_minor(minor));
}

void comedi_release_hardware_device(struct device *hardware_device)
{
        int minor;
        struct comedi_device *dev;

        for (minor = comedi_num_legacy_minors; minor < COMEDI_NUM_BOARD_MINORS;
             minor++) {
                mutex_lock(&comedi_board_minor_table_lock);
                dev = comedi_board_minor_table[minor];
                if (dev && dev->hw_dev == hardware_device) {
                        comedi_board_minor_table[minor] = NULL;
                        mutex_unlock(&comedi_board_minor_table_lock);
                        comedi_free_board_dev(dev);
                        break;
                }
                mutex_unlock(&comedi_board_minor_table_lock);
        }
}

int comedi_alloc_subdevice_minor(struct comedi_subdevice *s)
{
        struct comedi_device *dev = s->device;
        struct device *csdev;
        unsigned i;

        mutex_lock(&comedi_subdevice_minor_table_lock);
        for (i = 0; i < COMEDI_NUM_SUBDEVICE_MINORS; ++i) {
                if (comedi_subdevice_minor_table[i] == NULL) {
                        comedi_subdevice_minor_table[i] = s;
                        break;
                }
        }
        mutex_unlock(&comedi_subdevice_minor_table_lock);
        if (i == COMEDI_NUM_SUBDEVICE_MINORS) {
                pr_err("comedi: error: ran out of minor numbers for subdevice files.\n");
                return -EBUSY;
        }
        i += COMEDI_NUM_BOARD_MINORS;
        s->minor = i;
        csdev = device_create(comedi_class, dev->class_dev,
                              MKDEV(COMEDI_MAJOR, i), NULL, "comedi%i_subd%i",
                              dev->minor, s->index);
        if (!IS_ERR(csdev))
                s->class_dev = csdev;

        return 0;
}

void comedi_free_subdevice_minor(struct comedi_subdevice *s)
{
        unsigned int i;

        if (s == NULL)
                return;
        if (s->minor < 0)
                return;

        BUG_ON(s->minor >= COMEDI_NUM_MINORS);
        BUG_ON(s->minor < COMEDI_NUM_BOARD_MINORS);

        i = s->minor - COMEDI_NUM_BOARD_MINORS;
        mutex_lock(&comedi_subdevice_minor_table_lock);
        if (s == comedi_subdevice_minor_table[i])
                comedi_subdevice_minor_table[i] = NULL;
        mutex_unlock(&comedi_subdevice_minor_table_lock);
        if (s->class_dev) {
                device_destroy(comedi_class, MKDEV(COMEDI_MAJOR, s->minor));
                s->class_dev = NULL;
        }
}

static void comedi_cleanup_board_minors(void)
{
        unsigned i;

        for (i = 0; i < COMEDI_NUM_BOARD_MINORS; i++)
                comedi_free_board_minor(i);
}

static int __init comedi_init(void)
{
        int i;
        int retval;

        pr_info("comedi: version " COMEDI_RELEASE " - http://www.comedi.org\n");

        if (comedi_num_legacy_minors < 0 ||
            comedi_num_legacy_minors > COMEDI_NUM_BOARD_MINORS) {
                pr_err("comedi: error: invalid value for module parameter \"comedi_num_legacy_minors\".  Valid values are 0 through %i.\n",
                       COMEDI_NUM_BOARD_MINORS);
                return -EINVAL;
        }

        retval = register_chrdev_region(MKDEV(COMEDI_MAJOR, 0),
                                        COMEDI_NUM_MINORS, "comedi");
        if (retval)
                return -EIO;
        cdev_init(&comedi_cdev, &comedi_fops);
        comedi_cdev.owner = THIS_MODULE;
        kobject_set_name(&comedi_cdev.kobj, "comedi");
        if (cdev_add(&comedi_cdev, MKDEV(COMEDI_MAJOR, 0), COMEDI_NUM_MINORS)) {
                unregister_chrdev_region(MKDEV(COMEDI_MAJOR, 0),
                                         COMEDI_NUM_MINORS);
                return -EIO;
        }
        comedi_class = class_create(THIS_MODULE, "comedi");
        if (IS_ERR(comedi_class)) {
                pr_err("comedi: failed to create class\n");
                cdev_del(&comedi_cdev);
                unregister_chrdev_region(MKDEV(COMEDI_MAJOR, 0),
                                         COMEDI_NUM_MINORS);
                return PTR_ERR(comedi_class);
        }

        comedi_class->dev_groups = comedi_dev_groups;

        /* XXX requires /proc interface */
        comedi_proc_init();

        /* create devices files for legacy/manual use */
        for (i = 0; i < comedi_num_legacy_minors; i++) {
                struct comedi_device *dev;
                dev = comedi_alloc_board_minor(NULL);
                if (IS_ERR(dev)) {
                        comedi_cleanup_board_minors();
                        cdev_del(&comedi_cdev);
                        unregister_chrdev_region(MKDEV(COMEDI_MAJOR, 0),
                                                 COMEDI_NUM_MINORS);
                        return PTR_ERR(dev);
                } else {
                        /* comedi_alloc_board_minor() locked the mutex */
                        mutex_unlock(&dev->mutex);
                }
        }

        return 0;
}
module_init(comedi_init);

static void __exit comedi_cleanup(void)
{
        int i;

        comedi_cleanup_board_minors();
        for (i = 0; i < COMEDI_NUM_BOARD_MINORS; ++i)
                BUG_ON(comedi_board_minor_table[i]);
        for (i = 0; i < COMEDI_NUM_SUBDEVICE_MINORS; ++i)
                BUG_ON(comedi_subdevice_minor_table[i]);

        class_destroy(comedi_class);
        cdev_del(&comedi_cdev);
        unregister_chrdev_region(MKDEV(COMEDI_MAJOR, 0), COMEDI_NUM_MINORS);

        comedi_proc_cleanup();
}
module_exit(comedi_cleanup);

MODULE_AUTHOR("http://www.comedi.org");
MODULE_DESCRIPTION("Comedi core module");
MODULE_LICENSE("GPL");