w1.c

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/*
 *  w1.c
 *
 * Copyright (c) 2004 Evgeniy Polyakov <[email protected]>
 *
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/list.h>
#include <linux/interrupt.h>
#include <linux/spinlock.h>
#include <linux/timer.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/kthread.h>
#include <linux/freezer.h>

#include <linux/atomic.h>

#include "w1.h"
#include "w1_log.h"
#include "w1_int.h"
#include "w1_family.h"
#include "w1_netlink.h"

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Evgeniy Polyakov <[email protected]>");
MODULE_DESCRIPTION("Driver for 1-wire Dallas network protocol.");

static int w1_timeout = 10;
int w1_max_slave_count = 10;
int w1_max_slave_ttl = 10;

module_param_named(timeout, w1_timeout, int, 0);
module_param_named(max_slave_count, w1_max_slave_count, int, 0);
module_param_named(slave_ttl, w1_max_slave_ttl, int, 0);

DEFINE_MUTEX(w1_mlock);
LIST_HEAD(w1_masters);

static int w1_attach_slave_device(struct w1_master *dev, struct w1_reg_num *rn);

static int w1_master_match(struct device *dev, struct device_driver *drv)
{
    return 1;
}

static int w1_master_probe(struct device *dev)
{
    return -ENODEV;
}

static void w1_master_release(struct device *dev)
{
    struct w1_master *md = dev_to_w1_master(dev);

    dev_dbg(dev, "%s: Releasing %s.\n", __func__, md->name);
    memset(md, 0, sizeof(struct w1_master) + sizeof(struct w1_bus_master));
    kfree(md);
}

static void w1_slave_release(struct device *dev)
{
    struct w1_slave *sl = dev_to_w1_slave(dev);

    dev_dbg(dev, "%s: Releasing %s.\n", __func__, sl->name);

    while (atomic_read(&sl->refcnt)) {
        dev_dbg(dev, "Waiting for %s to become free: refcnt=%d.\n",
                sl->name, atomic_read(&sl->refcnt));
        if (msleep_interruptible(1000))
            flush_signals(current);
    }

    w1_family_put(sl->family);
    sl->master->slave_count--;

    complete(&sl->released);
}

static ssize_t w1_slave_read_name(struct device *dev, struct device_attribute *attr, char *buf)
{
    struct w1_slave *sl = dev_to_w1_slave(dev);

    return sprintf(buf, "%s\n", sl->name);
}

static ssize_t w1_slave_read_id(struct device *dev,
    struct device_attribute *attr, char *buf)
{
    struct w1_slave *sl = dev_to_w1_slave(dev);
    ssize_t count = sizeof(sl->reg_num);

    memcpy(buf, (u8 *)&sl->reg_num, count);
    return count;
}

static struct device_attribute w1_slave_attr_name =
    __ATTR(name, S_IRUGO, w1_slave_read_name, NULL);
static struct device_attribute w1_slave_attr_id =
    __ATTR(id, S_IRUGO, w1_slave_read_id, NULL);

/* Default family */

static ssize_t w1_default_write(struct file *filp, struct kobject *kobj,
                struct bin_attribute *bin_attr,
                char *buf, loff_t off, size_t count)
{
    struct w1_slave *sl = kobj_to_w1_slave(kobj);

    mutex_lock(&sl->master->mutex);
    if (w1_reset_select_slave(sl)) {
        count = 0;
        goto out_up;
    }

    w1_write_block(sl->master, buf, count);

out_up:
    mutex_unlock(&sl->master->mutex);
    return count;
}

static ssize_t w1_default_read(struct file *filp, struct kobject *kobj,
                   struct bin_attribute *bin_attr,
                   char *buf, loff_t off, size_t count)
{
    struct w1_slave *sl = kobj_to_w1_slave(kobj);

    mutex_lock(&sl->master->mutex);
    w1_read_block(sl->master, buf, count);
    mutex_unlock(&sl->master->mutex);
    return count;
}

static struct bin_attribute w1_default_attr = {
      .attr = {
              .name = "rw",
              .mode = S_IRUGO | S_IWUSR,
      },
      .size = PAGE_SIZE,
      .read = w1_default_read,
      .write = w1_default_write,
};

static int w1_default_add_slave(struct w1_slave *sl)
{
    return sysfs_create_bin_file(&sl->dev.kobj, &w1_default_attr);
}

static void w1_default_remove_slave(struct w1_slave *sl)
{
    sysfs_remove_bin_file(&sl->dev.kobj, &w1_default_attr);
}

static struct w1_family_ops w1_default_fops = {
    .add_slave  = w1_default_add_slave,
    .remove_slave   = w1_default_remove_slave,
};

static struct w1_family w1_default_family = {
    .fops = &w1_default_fops,
};

static int w1_uevent(struct device *dev, struct kobj_uevent_env *env);

static struct bus_type w1_bus_type = {
    .name = "w1",
    .match = w1_master_match,
    .uevent = w1_uevent,
};

struct device_driver w1_master_driver = {
    .name = "w1_master_driver",
    .bus = &w1_bus_type,
    .probe = w1_master_probe,
};

struct device w1_master_device = {
    .parent = NULL,
    .bus = &w1_bus_type,
    .init_name = "w1 bus master",
    .driver = &w1_master_driver,
    .release = &w1_master_release
};

static struct device_driver w1_slave_driver = {
    .name = "w1_slave_driver",
    .bus = &w1_bus_type,
};

#if 0
struct device w1_slave_device = {
    .parent = NULL,
    .bus = &w1_bus_type,
    .init_name = "w1 bus slave",
    .driver = &w1_slave_driver,
    .release = &w1_slave_release
};
#endif  /*  0  */

static ssize_t w1_master_attribute_show_name(struct device *dev, struct device_attribute *attr, char *buf)
{
    struct w1_master *md = dev_to_w1_master(dev);
    ssize_t count;

    mutex_lock(&md->mutex);
    count = sprintf(buf, "%s\n", md->name);
    mutex_unlock(&md->mutex);

    return count;
}

static ssize_t w1_master_attribute_store_search(struct device * dev,
                        struct device_attribute *attr,
                        const char * buf, size_t count)
{
    long tmp;
    struct w1_master *md = dev_to_w1_master(dev);

    if (strict_strtol(buf, 0, &tmp) == -EINVAL)
        return -EINVAL;

    mutex_lock(&md->mutex);
    md->search_count = tmp;
    mutex_unlock(&md->mutex);
    wake_up_process(md->thread);

    return count;
}

static ssize_t w1_master_attribute_show_search(struct device *dev,
                           struct device_attribute *attr,
                           char *buf)
{
    struct w1_master *md = dev_to_w1_master(dev);
    ssize_t count;

    mutex_lock(&md->mutex);
    count = sprintf(buf, "%d\n", md->search_count);
    mutex_unlock(&md->mutex);

    return count;
}

static ssize_t w1_master_attribute_store_pullup(struct device *dev,
                        struct device_attribute *attr,
                        const char *buf, size_t count)
{
    long tmp;
    struct w1_master *md = dev_to_w1_master(dev);

    if (strict_strtol(buf, 0, &tmp) == -EINVAL)
        return -EINVAL;

    mutex_lock(&md->mutex);
    md->enable_pullup = tmp;
    mutex_unlock(&md->mutex);
    wake_up_process(md->thread);

    return count;
}

static ssize_t w1_master_attribute_show_pullup(struct device *dev,
                           struct device_attribute *attr,
                           char *buf)
{
    struct w1_master *md = dev_to_w1_master(dev);
    ssize_t count;

    mutex_lock(&md->mutex);
    count = sprintf(buf, "%d\n", md->enable_pullup);
    mutex_unlock(&md->mutex);

    return count;
}

static ssize_t w1_master_attribute_show_pointer(struct device *dev, struct device_attribute *attr, char *buf)
{
    struct w1_master *md = dev_to_w1_master(dev);
    ssize_t count;

    mutex_lock(&md->mutex);
    count = sprintf(buf, "0x%p\n", md->bus_master);
    mutex_unlock(&md->mutex);
    return count;
}

static ssize_t w1_master_attribute_show_timeout(struct device *dev, struct device_attribute *attr, char *buf)
{
    ssize_t count;
    count = sprintf(buf, "%d\n", w1_timeout);
    return count;
}

static ssize_t w1_master_attribute_show_max_slave_count(struct device *dev, struct device_attribute *attr, char *buf)
{
    struct w1_master *md = dev_to_w1_master(dev);
    ssize_t count;

    mutex_lock(&md->mutex);
    count = sprintf(buf, "%d\n", md->max_slave_count);
    mutex_unlock(&md->mutex);
    return count;
}

static ssize_t w1_master_attribute_show_attempts(struct device *dev, struct device_attribute *attr, char *buf)
{
    struct w1_master *md = dev_to_w1_master(dev);
    ssize_t count;

    mutex_lock(&md->mutex);
    count = sprintf(buf, "%lu\n", md->attempts);
    mutex_unlock(&md->mutex);
    return count;
}

static ssize_t w1_master_attribute_show_slave_count(struct device *dev, struct device_attribute *attr, char *buf)
{
    struct w1_master *md = dev_to_w1_master(dev);
    ssize_t count;

    mutex_lock(&md->mutex);
    count = sprintf(buf, "%d\n", md->slave_count);
    mutex_unlock(&md->mutex);
    return count;
}

static ssize_t w1_master_attribute_show_slaves(struct device *dev,
    struct device_attribute *attr, char *buf)
{
    struct w1_master *md = dev_to_w1_master(dev);
    int c = PAGE_SIZE;

    mutex_lock(&md->mutex);

    if (md->slave_count == 0)
        c -= snprintf(buf + PAGE_SIZE - c, c, "not found.\n");
    else {
        struct list_head *ent, *n;
        struct w1_slave *sl;

        list_for_each_safe(ent, n, &md->slist) {
            sl = list_entry(ent, struct w1_slave, w1_slave_entry);

            c -= snprintf(buf + PAGE_SIZE - c, c, "%s\n", sl->name);
        }
    }

    mutex_unlock(&md->mutex);

    return PAGE_SIZE - c;
}

static ssize_t w1_master_attribute_show_add(struct device *dev,
    struct device_attribute *attr, char *buf)
{
    int c = PAGE_SIZE;
    c -= snprintf(buf+PAGE_SIZE - c, c,
        "write device id xx-xxxxxxxxxxxx to add slave\n");
    return PAGE_SIZE - c;
}

static int w1_atoreg_num(struct device *dev, const char *buf, size_t count,
    struct w1_reg_num *rn)
{
    unsigned int family;
    unsigned long long id;
    int i;
    u64 rn64_le;

    /* The CRC value isn't read from the user because the sysfs directory
     * doesn't include it and most messages from the bus search don't
     * print it either.  It would be unreasonable for the user to then
     * provide it.
     */
    const char *error_msg = "bad slave string format, expecting "
        "ff-dddddddddddd\n";

    if (buf[2] != '-') {
        dev_err(dev, "%s", error_msg);
        return -EINVAL;
    }
    i = sscanf(buf, "%02x-%012llx", &family, &id);
    if (i != 2) {
        dev_err(dev, "%s", error_msg);
        return -EINVAL;
    }
    rn->family = family;
    rn->id = id;

    rn64_le = cpu_to_le64(*(u64 *)rn);
    rn->crc = w1_calc_crc8((u8 *)&rn64_le, 7);

#if 0
    dev_info(dev, "With CRC device is %02x.%012llx.%02x.\n",
          rn->family, (unsigned long long)rn->id, rn->crc);
#endif

    return 0;
}

/* Searches the slaves in the w1_master and returns a pointer or NULL.
 * Note: must hold the mutex
 */
static struct w1_slave *w1_slave_search_device(struct w1_master *dev,
    struct w1_reg_num *rn)
{
    struct w1_slave *sl;
    list_for_each_entry(sl, &dev->slist, w1_slave_entry) {
        if (sl->reg_num.family == rn->family &&
                sl->reg_num.id == rn->id &&
                sl->reg_num.crc == rn->crc) {
            return sl;
        }
    }
    return NULL;
}

static ssize_t w1_master_attribute_store_add(struct device *dev,
                        struct device_attribute *attr,
                        const char *buf, size_t count)
{
    struct w1_master *md = dev_to_w1_master(dev);
    struct w1_reg_num rn;
    struct w1_slave *sl;
    ssize_t result = count;

    if (w1_atoreg_num(dev, buf, count, &rn))
        return -EINVAL;

    mutex_lock(&md->mutex);
    sl = w1_slave_search_device(md, &rn);
    /* It would be nice to do a targeted search one the one-wire bus
     * for the new device to see if it is out there or not.  But the
     * current search doesn't support that.
     */
    if (sl) {
        dev_info(dev, "Device %s already exists\n", sl->name);
        result = -EINVAL;
    } else {
        w1_attach_slave_device(md, &rn);
    }
    mutex_unlock(&md->mutex);

    return result;
}

static ssize_t w1_master_attribute_show_remove(struct device *dev,
    struct device_attribute *attr, char *buf)
{
    int c = PAGE_SIZE;
    c -= snprintf(buf+PAGE_SIZE - c, c,
        "write device id xx-xxxxxxxxxxxx to remove slave\n");
    return PAGE_SIZE - c;
}

static ssize_t w1_master_attribute_store_remove(struct device *dev,
                        struct device_attribute *attr,
                        const char *buf, size_t count)
{
    struct w1_master *md = dev_to_w1_master(dev);
    struct w1_reg_num rn;
    struct w1_slave *sl;
    ssize_t result = count;

    if (w1_atoreg_num(dev, buf, count, &rn))
        return -EINVAL;

    mutex_lock(&md->mutex);
    sl = w1_slave_search_device(md, &rn);
    if (sl) {
        w1_slave_detach(sl);
    } else {
        dev_info(dev, "Device %02x-%012llx doesn't exists\n", rn.family,
            (unsigned long long)rn.id);
        result = -EINVAL;
    }
    mutex_unlock(&md->mutex);

    return result;
}

#define W1_MASTER_ATTR_RO(_name, _mode)             \
    struct device_attribute w1_master_attribute_##_name =   \
        __ATTR(w1_master_##_name, _mode,        \
               w1_master_attribute_show_##_name, NULL)

#define W1_MASTER_ATTR_RW(_name, _mode)             \
    struct device_attribute w1_master_attribute_##_name =   \
        __ATTR(w1_master_##_name, _mode,        \
               w1_master_attribute_show_##_name,    \
               w1_master_attribute_store_##_name)

static W1_MASTER_ATTR_RO(name, S_IRUGO);
static W1_MASTER_ATTR_RO(slaves, S_IRUGO);
static W1_MASTER_ATTR_RO(slave_count, S_IRUGO);
static W1_MASTER_ATTR_RO(max_slave_count, S_IRUGO);
static W1_MASTER_ATTR_RO(attempts, S_IRUGO);
static W1_MASTER_ATTR_RO(timeout, S_IRUGO);
static W1_MASTER_ATTR_RO(pointer, S_IRUGO);
static W1_MASTER_ATTR_RW(search, S_IRUGO | S_IWUSR | S_IWGRP);
static W1_MASTER_ATTR_RW(pullup, S_IRUGO | S_IWUSR | S_IWGRP);
static W1_MASTER_ATTR_RW(add, S_IRUGO | S_IWUSR | S_IWGRP);
static W1_MASTER_ATTR_RW(remove, S_IRUGO | S_IWUSR | S_IWGRP);

static struct attribute *w1_master_default_attrs[] = {
    &w1_master_attribute_name.attr,
    &w1_master_attribute_slaves.attr,
    &w1_master_attribute_slave_count.attr,
    &w1_master_attribute_max_slave_count.attr,
    &w1_master_attribute_attempts.attr,
    &w1_master_attribute_timeout.attr,
    &w1_master_attribute_pointer.attr,
    &w1_master_attribute_search.attr,
    &w1_master_attribute_pullup.attr,
    &w1_master_attribute_add.attr,
    &w1_master_attribute_remove.attr,
    NULL
};

static struct attribute_group w1_master_defattr_group = {
    .attrs = w1_master_default_attrs,
};

int w1_create_master_attributes(struct w1_master *master)
{
    return sysfs_create_group(&master->dev.kobj, &w1_master_defattr_group);
}

void w1_destroy_master_attributes(struct w1_master *master)
{
    sysfs_remove_group(&master->dev.kobj, &w1_master_defattr_group);
}

#ifdef CONFIG_HOTPLUG
static int w1_uevent(struct device *dev, struct kobj_uevent_env *env)
{
    struct w1_master *md = NULL;
    struct w1_slave *sl = NULL;
    char *event_owner, *name;
    int err = 0;

    if (dev->driver == &w1_master_driver) {
        md = container_of(dev, struct w1_master, dev);
        event_owner = "master";
        name = md->name;
    } else if (dev->driver == &w1_slave_driver) {
        sl = container_of(dev, struct w1_slave, dev);
        event_owner = "slave";
        name = sl->name;
    } else {
        dev_dbg(dev, "Unknown event.\n");
        return -EINVAL;
    }

    dev_dbg(dev, "Hotplug event for %s %s, bus_id=%s.\n",
            event_owner, name, dev_name(dev));

    if (dev->driver != &w1_slave_driver || !sl)
        goto end;

    err = add_uevent_var(env, "W1_FID=%02X", sl->reg_num.family);
    if (err)
        goto end;

    err = add_uevent_var(env, "W1_SLAVE_ID=%024LX",
                 (unsigned long long)sl->reg_num.id);
end:
    return err;
}
#else
static int w1_uevent(struct device *dev, struct kobj_uevent_env *env)
{
    return 0;
}
#endif

static int __w1_attach_slave_device(struct w1_slave *sl)
{
    int err;

    sl->dev.parent = &sl->master->dev;
    sl->dev.driver = &w1_slave_driver;
    sl->dev.bus = &w1_bus_type;
    sl->dev.release = &w1_slave_release;

    dev_set_name(&sl->dev, "%02x-%012llx",
         (unsigned int) sl->reg_num.family,
         (unsigned long long) sl->reg_num.id);
    snprintf(&sl->name[0], sizeof(sl->name),
         "%02x-%012llx",
         (unsigned int) sl->reg_num.family,
         (unsigned long long) sl->reg_num.id);

    dev_dbg(&sl->dev, "%s: registering %s as %p.\n", __func__,
        dev_name(&sl->dev), sl);

    err = device_register(&sl->dev);
    if (err < 0) {
        dev_err(&sl->dev,
            "Device registration [%s] failed. err=%d\n",
            dev_name(&sl->dev), err);
        return err;
    }

    /* Create "name" entry */
    err = device_create_file(&sl->dev, &w1_slave_attr_name);
    if (err < 0) {
        dev_err(&sl->dev,
            "sysfs file creation for [%s] failed. err=%d\n",
            dev_name(&sl->dev), err);
        goto out_unreg;
    }

    /* Create "id" entry */
    err = device_create_file(&sl->dev, &w1_slave_attr_id);
    if (err < 0) {
        dev_err(&sl->dev,
            "sysfs file creation for [%s] failed. err=%d\n",
            dev_name(&sl->dev), err);
        goto out_rem1;
    }

    /* if the family driver needs to initialize something... */
    if (sl->family->fops && sl->family->fops->add_slave &&
        ((err = sl->family->fops->add_slave(sl)) < 0)) {
        dev_err(&sl->dev,
            "sysfs file creation for [%s] failed. err=%d\n",
            dev_name(&sl->dev), err);
        goto out_rem2;
    }

    list_add_tail(&sl->w1_slave_entry, &sl->master->slist);

    return 0;

out_rem2:
    device_remove_file(&sl->dev, &w1_slave_attr_id);
out_rem1:
    device_remove_file(&sl->dev, &w1_slave_attr_name);
out_unreg:
    device_unregister(&sl->dev);
    return err;
}

static int w1_attach_slave_device(struct w1_master *dev, struct w1_reg_num *rn)
{
    struct w1_slave *sl;
    struct w1_family *f;
    int err;
    struct w1_netlink_msg msg;

    sl = kzalloc(sizeof(struct w1_slave), GFP_KERNEL);
    if (!sl) {
        dev_err(&dev->dev,
             "%s: failed to allocate new slave device.\n",
             __func__);
        return -ENOMEM;
    }


    sl->owner = THIS_MODULE;
    sl->master = dev;
    set_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);

    memset(&msg, 0, sizeof(msg));
    memcpy(&sl->reg_num, rn, sizeof(sl->reg_num));
    atomic_set(&sl->refcnt, 0);
    init_completion(&sl->released);

    spin_lock(&w1_flock);
    f = w1_family_registered(rn->family);
    if (!f) {
        f= &w1_default_family;
        dev_info(&dev->dev, "Family %x for %02x.%012llx.%02x is not registered.\n",
              rn->family, rn->family,
              (unsigned long long)rn->id, rn->crc);
    }
    __w1_family_get(f);
    spin_unlock(&w1_flock);

    sl->family = f;


    err = __w1_attach_slave_device(sl);
    if (err < 0) {
        dev_err(&dev->dev, "%s: Attaching %s failed.\n", __func__,
             sl->name);
        w1_family_put(sl->family);
        kfree(sl);
        return err;
    }

    sl->ttl = dev->slave_ttl;
    dev->slave_count++;

    memcpy(msg.id.id, rn, sizeof(msg.id));
    msg.type = W1_SLAVE_ADD;
    w1_netlink_send(dev, &msg);

    return 0;
}

void w1_slave_detach(struct w1_slave *sl)
{
    struct w1_netlink_msg msg;

    dev_dbg(&sl->dev, "%s: detaching %s [%p].\n", __func__, sl->name, sl);

    list_del(&sl->w1_slave_entry);

    if (sl->family->fops && sl->family->fops->remove_slave)
        sl->family->fops->remove_slave(sl);

    memset(&msg, 0, sizeof(msg));
    memcpy(msg.id.id, &sl->reg_num, sizeof(msg.id));
    msg.type = W1_SLAVE_REMOVE;
    w1_netlink_send(sl->master, &msg);

    device_remove_file(&sl->dev, &w1_slave_attr_id);
    device_remove_file(&sl->dev, &w1_slave_attr_name);
    device_unregister(&sl->dev);

    wait_for_completion(&sl->released);
    kfree(sl);
}

struct w1_master *w1_search_master_id(u32 id)
{
    struct w1_master *dev;
    int found = 0;

    mutex_lock(&w1_mlock);
    list_for_each_entry(dev, &w1_masters, w1_master_entry) {
        if (dev->id == id) {
            found = 1;
            atomic_inc(&dev->refcnt);
            break;
        }
    }
    mutex_unlock(&w1_mlock);

    return (found)?dev:NULL;
}

struct w1_slave *w1_search_slave(struct w1_reg_num *id)
{
    struct w1_master *dev;
    struct w1_slave *sl = NULL;
    int found = 0;

    mutex_lock(&w1_mlock);
    list_for_each_entry(dev, &w1_masters, w1_master_entry) {
        mutex_lock(&dev->mutex);
        list_for_each_entry(sl, &dev->slist, w1_slave_entry) {
            if (sl->reg_num.family == id->family &&
                    sl->reg_num.id == id->id &&
                    sl->reg_num.crc == id->crc) {
                found = 1;
                atomic_inc(&dev->refcnt);
                atomic_inc(&sl->refcnt);
                break;
            }
        }
        mutex_unlock(&dev->mutex);

        if (found)
            break;
    }
    mutex_unlock(&w1_mlock);

    return (found)?sl:NULL;
}

void w1_reconnect_slaves(struct w1_family *f, int attach)
{
    struct w1_slave *sl, *sln;
    struct w1_master *dev;

    mutex_lock(&w1_mlock);
    list_for_each_entry(dev, &w1_masters, w1_master_entry) {
        dev_dbg(&dev->dev, "Reconnecting slaves in device %s "
            "for family %02x.\n", dev->name, f->fid);
        mutex_lock(&dev->mutex);
        list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
            /* If it is a new family, slaves with the default
             * family driver and are that family will be
             * connected.  If the family is going away, devices
             * matching that family are reconneced.
             */
            if ((attach && sl->family->fid == W1_FAMILY_DEFAULT
                && sl->reg_num.family == f->fid) ||
                (!attach && sl->family->fid == f->fid)) {
                struct w1_reg_num rn;

                memcpy(&rn, &sl->reg_num, sizeof(rn));
                w1_slave_detach(sl);

                w1_attach_slave_device(dev, &rn);
            }
        }
        dev_dbg(&dev->dev, "Reconnecting slaves in device %s "
            "has been finished.\n", dev->name);
        mutex_unlock(&dev->mutex);
    }
    mutex_unlock(&w1_mlock);
}

void w1_slave_found(struct w1_master *dev, u64 rn)
{
    struct w1_slave *sl;
    struct w1_reg_num *tmp;
    u64 rn_le = cpu_to_le64(rn);

    atomic_inc(&dev->refcnt);

    tmp = (struct w1_reg_num *) &rn;

    sl = w1_slave_search_device(dev, tmp);
    if (sl) {
        set_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);
    } else {
        if (rn && tmp->crc == w1_calc_crc8((u8 *)&rn_le, 7))
            w1_attach_slave_device(dev, tmp);
    }

    atomic_dec(&dev->refcnt);
}

void w1_search(struct w1_master *dev, u8 search_type, w1_slave_found_callback cb)
{
    u64 last_rn, rn, tmp64;
    int i, slave_count = 0;
    int last_zero, last_device;
    int search_bit, desc_bit;
    u8  triplet_ret = 0;

    search_bit = 0;
    rn = last_rn = 0;
    last_device = 0;
    last_zero = -1;

    desc_bit = 64;

    while ( !last_device && (slave_count++ < dev->max_slave_count) ) {
        last_rn = rn;
        rn = 0;

        /*
         * Reset bus and all 1-wire device state machines
         * so they can respond to our requests.
         *
         * Return 0 - device(s) present, 1 - no devices present.
         */
        mutex_lock(&dev->bus_mutex);
        if (w1_reset_bus(dev)) {
            mutex_unlock(&dev->bus_mutex);
            dev_dbg(&dev->dev, "No devices present on the wire.\n");
            break;
        }

        /* Do fast search on single slave bus */
        if (dev->max_slave_count == 1) {
            int rv;
            w1_write_8(dev, W1_READ_ROM);
            rv = w1_read_block(dev, (u8 *)&rn, 8);
            mutex_unlock(&dev->bus_mutex);

            if (rv == 8 && rn)
                cb(dev, rn);

            break;
        }

        /* Start the search */
        w1_write_8(dev, search_type);
        for (i = 0; i < 64; ++i) {
            /* Determine the direction/search bit */
            if (i == desc_bit)
                search_bit = 1;   /* took the 0 path last time, so take the 1 path */
            else if (i > desc_bit)
                search_bit = 0;   /* take the 0 path on the next branch */
            else
                search_bit = ((last_rn >> i) & 0x1);

            triplet_ret = w1_triplet(dev, search_bit);

            /* quit if no device responded */
            if ( (triplet_ret & 0x03) == 0x03 )
                break;

            /* If both directions were valid, and we took the 0 path... */
            if (triplet_ret == 0)
                last_zero = i;

            /* extract the direction taken & update the device number */
            tmp64 = (triplet_ret >> 2);
            rn |= (tmp64 << i);

            if (kthread_should_stop()) {
                mutex_unlock(&dev->bus_mutex);
                dev_dbg(&dev->dev, "Abort w1_search\n");
                return;
            }
        }
        mutex_unlock(&dev->bus_mutex);

        if ( (triplet_ret & 0x03) != 0x03 ) {
            if ( (desc_bit == last_zero) || (last_zero < 0))
                last_device = 1;
            desc_bit = last_zero;
            cb(dev, rn);
        }
    }
}

void w1_search_process_cb(struct w1_master *dev, u8 search_type,
    w1_slave_found_callback cb)
{
    struct w1_slave *sl, *sln;

    list_for_each_entry(sl, &dev->slist, w1_slave_entry)
        clear_bit(W1_SLAVE_ACTIVE, (long *)&sl->flags);

    w1_search_devices(dev, search_type, cb);

    list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
        if (!test_bit(W1_SLAVE_ACTIVE, (unsigned long *)&sl->flags) && !--sl->ttl)
            w1_slave_detach(sl);
        else if (test_bit(W1_SLAVE_ACTIVE, (unsigned long *)&sl->flags))
            sl->ttl = dev->slave_ttl;
    }

    if (dev->search_count > 0)
        dev->search_count--;
}

static void w1_search_process(struct w1_master *dev, u8 search_type)
{
    w1_search_process_cb(dev, search_type, w1_slave_found);
}

int w1_process(void *data)
{
    struct w1_master *dev = (struct w1_master *) data;
    /* As long as w1_timeout is only set by a module parameter the sleep
     * time can be calculated in jiffies once.
     */
    const unsigned long jtime = msecs_to_jiffies(w1_timeout * 1000);

    while (!kthread_should_stop()) {
        if (dev->search_count) {
            mutex_lock(&dev->mutex);
            w1_search_process(dev, W1_SEARCH);
            mutex_unlock(&dev->mutex);
        }

        try_to_freeze();
        __set_current_state(TASK_INTERRUPTIBLE);

        if (kthread_should_stop())
            break;

        /* Only sleep when the search is active. */
        if (dev->search_count)
            schedule_timeout(jtime);
        else
            schedule();
    }

    atomic_dec(&dev->refcnt);

    return 0;
}

static int __init w1_init(void)
{
    int retval;

    printk(KERN_INFO "Driver for 1-wire Dallas network protocol.\n");

    w1_init_netlink();

    retval = bus_register(&w1_bus_type);
    if (retval) {
        printk(KERN_ERR "Failed to register bus. err=%d.\n", retval);
        goto err_out_exit_init;
    }

    retval = driver_register(&w1_master_driver);
    if (retval) {
        printk(KERN_ERR
            "Failed to register master driver. err=%d.\n",
            retval);
        goto err_out_bus_unregister;
    }

    retval = driver_register(&w1_slave_driver);
    if (retval) {
        printk(KERN_ERR
            "Failed to register slave driver. err=%d.\n",
            retval);
        goto err_out_master_unregister;
    }

    return 0;

#if 0
/* For undoing the slave register if there was a step after it. */
err_out_slave_unregister:
    driver_unregister(&w1_slave_driver);
#endif

err_out_master_unregister:
    driver_unregister(&w1_master_driver);

err_out_bus_unregister:
    bus_unregister(&w1_bus_type);

err_out_exit_init:
    return retval;
}

static void __exit w1_fini(void)
{
    struct w1_master *dev;

    /* Set netlink removal messages and some cleanup */
    list_for_each_entry(dev, &w1_masters, w1_master_entry)
        __w1_remove_master_device(dev);

    w1_fini_netlink();

    driver_unregister(&w1_slave_driver);
    driver_unregister(&w1_master_driver);
    bus_unregister(&w1_bus_type);
}

module_init(w1_init);
module_exit(w1_fini);