/*

   * Copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net>

   *

   * 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 <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/hwmon.h>

  #include <linux/atomic.h>

  #include "w1_internal.h"

  #include "w1_netlink.h"

  #define W1_FAMILY_DEFAULT	0

  static int w1_timeout = 10;

  module_param_named(timeout, w1_timeout, int, 0);

  MODULE_PARM_DESC(timeout, "time in seconds between automatic slave searches");

  
  static int w1_timeout_us = 0;

  module_param_named(timeout_us, w1_timeout_us, int, 0);

  MODULE_PARM_DESC(timeout_us,
  		 "time in microseconds between automatic slave searches");

  /* A search stops when w1_max_slave_count devices have been found in that
   * search.  The next search will start over and detect the same set of devices
   * on a static 1-wire bus.  Memory is not allocated based on this number, just
   * on the number of devices known to the kernel.  Having a high number does not
   * consume additional resources.  As a special case, if there is only one
   * device on the network and w1_max_slave_count is set to 1, the device id can
   * be read directly skipping the normal slower search process.
   */

  int w1_max_slave_count = 64;

  module_param_named(max_slave_count, w1_max_slave_count, int, 0);

  MODULE_PARM_DESC(max_slave_count,
  	"maximum number of slaves detected in a search");

  
  int w1_max_slave_ttl = 10;

  module_param_named(slave_ttl, w1_max_slave_ttl, int, 0);

  MODULE_PARM_DESC(slave_ttl,
  	"Number of searches not seeing a slave before it will be removed");

  DEFINE_MUTEX(w1_mlock);

  LIST_HEAD(w1_masters);

  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.
  ", __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 [%p]
  ", __func__, sl->name, sl);

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

  }

  static ssize_t name_show(struct device *dev, struct device_attribute *attr, char *buf)

  {

  	struct w1_slave *sl = dev_to_w1_slave(dev);

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

  }

  static DEVICE_ATTR_RO(name);

  static ssize_t id_show(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 DEVICE_ATTR_RO(id);

  static struct attribute *w1_slave_attrs[] = {
  	&dev_attr_name.attr,
  	&dev_attr_id.attr,
  	NULL,
  };
  ATTRIBUTE_GROUPS(w1_slave);

  /* Default family */

  static ssize_t rw_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 rw_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 BIN_ATTR_RW(rw, PAGE_SIZE);
  
  static struct bin_attribute *w1_slave_bin_attrs[] = {
  	&bin_attr_rw,
  	NULL,

  };

  static const struct attribute_group w1_slave_default_group = {
  	.bin_attrs = w1_slave_bin_attrs,
  };

  static const struct attribute_group *w1_slave_default_groups[] = {
  	&w1_slave_default_group,
  	NULL,
  };

  
  static struct w1_family_ops w1_default_fops = {

  	.groups		= w1_slave_default_groups,

  };
  
  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
  ", 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);

  	int ret;

  	ret = kstrtol(buf, 0, &tmp);
  	if (ret)
  		return ret;

  	mutex_lock(&md->mutex);

  	md->search_count = tmp;

  	mutex_unlock(&md->mutex);

  	/* Only wake if it is going to be searching. */
  	if (tmp)
  		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
  ", 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);

  	int ret;

  	ret = kstrtol(buf, 0, &tmp);
  	if (ret)
  		return ret;

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

  
  	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
  ", 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
  ", 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
  ", w1_timeout);
  	return count;
  }

  static ssize_t w1_master_attribute_show_timeout_us(struct device *dev,
  	struct device_attribute *attr, char *buf)
  {
  	ssize_t count;
  	count = sprintf(buf, "%d
  ", w1_timeout_us);
  	return count;
  }

  static ssize_t w1_master_attribute_store_max_slave_count(struct device *dev,
  	struct device_attribute *attr, const char *buf, size_t count)
  {

  	int tmp;

  	struct w1_master *md = dev_to_w1_master(dev);

  	if (kstrtoint(buf, 0, &tmp) || tmp < 1)

  		return -EINVAL;
  
  	mutex_lock(&md->mutex);
  	md->max_slave_count = tmp;
  	/* allow each time the max_slave_count is updated */
  	clear_bit(W1_WARN_MAX_COUNT, &md->flags);
  	mutex_unlock(&md->mutex);
  
  	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
  ", 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
  ", 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
  ", 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;

  	struct list_head *ent, *n;
  	struct w1_slave *sl = NULL;

  	mutex_lock(&md->list_mutex);

  	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
  ", sl->name);

  	}

  	if (!sl)
  		c -= snprintf(buf + PAGE_SIZE - c, c, "not found.
  ");

  	mutex_unlock(&md->list_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
  ");
  	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
  ";
  
  	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.
  ",
  		  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 not hold list_mutex

   */

  struct w1_slave *w1_slave_search_device(struct w1_master *dev,

  	struct w1_reg_num *rn)
  {
  	struct w1_slave *sl;

  	mutex_lock(&dev->list_mutex);

  	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) {

  			mutex_unlock(&dev->list_mutex);

  			return sl;
  		}
  	}

  	mutex_unlock(&dev->list_mutex);

  	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
  ", 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
  ");
  	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) {

  		result = w1_slave_detach(sl);
  		/* refcnt 0 means it was detached in the call */
  		if (result == 0)
  			result = count;

  	} else {
  		dev_info(dev, "Device %02x-%012llx doesn't exists
  ", 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_RW(max_slave_count, S_IRUGO | S_IWUSR | S_IWGRP);

  static W1_MASTER_ATTR_RO(attempts, S_IRUGO);
  static W1_MASTER_ATTR_RO(timeout, S_IRUGO);

  static W1_MASTER_ATTR_RO(timeout_us, 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_timeout_us.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 const 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);
  }

  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.
  ");

  		return -EINVAL;
  	}

  	dev_dbg(dev, "Hotplug event for %s %s, bus_id=%s.
  ",

  			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;
  }

  static int w1_family_notify(unsigned long action, struct w1_slave *sl)

  {

  	struct w1_family_ops *fops;

  	int err;

  	fops = sl->family->fops;

  	if (!fops)
  		return 0;

  	switch (action) {
  	case BUS_NOTIFY_ADD_DEVICE:

  		/* if the family driver needs to initialize something... */

  		if (fops->add_slave) {
  			err = fops->add_slave(sl);
  			if (err < 0) {
  				dev_err(&sl->dev,
  					"add_slave() call failed. err=%d
  ",
  					err);
  				return err;
  			}
  		}
  		if (fops->groups) {
  			err = sysfs_create_groups(&sl->dev.kobj, fops->groups);
  			if (err) {
  				dev_err(&sl->dev,
  					"sysfs group creation failed. err=%d
  ",
  					err);
  				return err;
  			}

  		}

  		if (IS_REACHABLE(CONFIG_HWMON) && fops->chip_info) {
  			struct device *hwmon
  				= hwmon_device_register_with_info(&sl->dev,
  						"w1_slave_temp", sl,
  						fops->chip_info,
  						NULL);
  			if (IS_ERR(hwmon)) {
  				dev_warn(&sl->dev,
  					 "could not create hwmon device
  ");
  			} else {
  				sl->hwmon = hwmon;
  			}
  		}

  		break;
  	case BUS_NOTIFY_DEL_DEVICE:

  		if (IS_REACHABLE(CONFIG_HWMON) && fops->chip_info &&
  			    sl->hwmon)
  			hwmon_device_unregister(sl->hwmon);

  		if (fops->remove_slave)

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

  		if (fops->groups)
  			sysfs_remove_groups(&sl->dev.kobj, fops->groups);

  		break;
  	}
  	return 0;
  }

  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;

  	sl->dev.groups = w1_slave_groups;

  	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.
  ", __func__,

  		dev_name(&sl->dev), sl);

  	/* suppress for w1_family_notify before sending KOBJ_ADD */
  	dev_set_uevent_suppress(&sl->dev, true);

  	err = device_register(&sl->dev);
  	if (err < 0) {
  		dev_err(&sl->dev,

  			"Device registration [%s] failed. err=%d
  ",

  			dev_name(&sl->dev), err);

  		return err;
  	}

  	w1_family_notify(BUS_NOTIFY_ADD_DEVICE, sl);

  	dev_set_uevent_suppress(&sl->dev, false);
  	kobject_uevent(&sl->dev.kobj, KOBJ_ADD);

  	mutex_lock(&sl->master->list_mutex);

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

  	mutex_unlock(&sl->master->list_mutex);

  
  	return 0;
  }

  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.
  ",
  			 __func__);
  		return -ENOMEM;
  	}

  
  	sl->owner = THIS_MODULE;
  	sl->master = dev;

  	set_bit(W1_SLAVE_ACTIVE, &sl->flags);

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

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

  	atomic_set(&sl->refcnt, 1);
  	atomic_inc(&sl->master->refcnt);

  	dev->slave_count++;

  	dev_info(&dev->dev, "Attaching one wire slave %02x.%012llx crc %02x
  ",
  		  rn->family, (unsigned long long)rn->id, rn->crc);

  	/* slave modules need to be loaded in a context with unlocked mutex */
  	mutex_unlock(&dev->mutex);

  	request_module("w1-family-0x%02X", rn->family);

  	mutex_lock(&dev->mutex);

  	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.
  ",
  			  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.
  ", __func__,
  			 sl->name);

  		dev->slave_count--;

  		w1_family_put(sl->family);

  		atomic_dec(&sl->master->refcnt);

  		kfree(sl);
  		return err;
  	}
  
  	sl->ttl = dev->slave_ttl;

  	memcpy(msg.id.id, rn, sizeof(msg.id));

  	msg.type = W1_SLAVE_ADD;
  	w1_netlink_send(dev, &msg);
  
  	return 0;
  }

  int w1_unref_slave(struct w1_slave *sl)

  {

  	struct w1_master *dev = sl->master;
  	int refcnt;
  	mutex_lock(&dev->list_mutex);
  	refcnt = atomic_sub_return(1, &sl->refcnt);
  	if (refcnt == 0) {
  		struct w1_netlink_msg msg;
  
  		dev_dbg(&sl->dev, "%s: detaching %s [%p].
  ", __func__,
  			sl->name, sl);
  
  		list_del(&sl->w1_slave_entry);
  
  		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);

  		w1_family_notify(BUS_NOTIFY_DEL_DEVICE, sl);

  		device_unregister(&sl->dev);
  		#ifdef DEBUG
  		memset(sl, 0, sizeof(*sl));
  		#endif
  		kfree(sl);
  	}
  	atomic_dec(&dev->refcnt);
  	mutex_unlock(&dev->list_mutex);
  	return refcnt;
  }

  int w1_slave_detach(struct w1_slave *sl)
  {
  	/* Only detach a slave once as it decreases the refcnt each time. */
  	int destroy_now;
  	mutex_lock(&sl->master->list_mutex);
  	destroy_now = !test_bit(W1_SLAVE_DETACH, &sl->flags);
  	set_bit(W1_SLAVE_DETACH, &sl->flags);
  	mutex_unlock(&sl->master->list_mutex);
  
  	if (destroy_now)
  		destroy_now = !w1_unref_slave(sl);
  	return destroy_now ? 0 : -EBUSY;

  }

  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->list_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->list_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.
  ", dev->name, f->fid);
  		mutex_lock(&dev->mutex);

  		mutex_lock(&dev->list_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;

  				mutex_unlock(&dev->list_mutex);

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

  				/* If it was already in use let the automatic
  				 * scan pick it up again later.
  				 */
  				if (!w1_slave_detach(sl))
  					w1_attach_slave_device(dev, &rn);
  				mutex_lock(&dev->list_mutex);

  			}
  		}
  		dev_dbg(&dev->dev, "Reconnecting slaves in device %s "
  			"has been finished.
  ", dev->name);

  		mutex_unlock(&dev->list_mutex);

  		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, &sl->flags);

  	} else {
  		if (rn && tmp->crc == w1_calc_crc8((u8 *)&rn_le, 7))
  			w1_attach_slave_device(dev, tmp);

  	}

  	atomic_dec(&dev->refcnt);
  }

  /**

   * w1_search() - Performs a ROM Search & registers any devices found.
   * @dev: The master device to search
   * @search_type: W1_SEARCH to search all devices, or W1_ALARM_SEARCH
   * to return only devices in the alarmed state
   * @cb: Function to call when a device is found
   *

   * The 1-wire search is a simple binary tree search.
   * For each bit of the address, we read two bits and write one bit.
   * The bit written will put to sleep all devies that don't match that bit.
   * When the two reads differ, the direction choice is obvious.
   * When both bits are 0, we must choose a path to take.
   * When we can scan all 64 bits without having to choose a path, we are done.
   *
   * See "Application note 187 1-wire search algorithm" at www.maxim-ic.com
   *

   */

  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 = dev->search_id;
  	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.
  ");

  			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);

  			/* Read two bits and write one bit */

  			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 (test_bit(W1_ABORT_SEARCH, &dev->flags)) {

  				mutex_unlock(&dev->bus_mutex);

  				dev_dbg(&dev->dev, "Abort w1_search
  ");

  				return;
  			}

  		}

  		mutex_unlock(&dev->bus_mutex);

  		if ( (triplet_ret & 0x03) != 0x03 ) {

  			if ((desc_bit == last_zero) || (last_zero < 0)) {

  				last_device = 1;

  				dev->search_id = 0;
  			} else {
  				dev->search_id = rn;
  			}

  			desc_bit = last_zero;

  			cb(dev, rn);

  		}

  
  		if (!last_device && slave_count == dev->max_slave_count &&
  			!test_bit(W1_WARN_MAX_COUNT, &dev->flags)) {

  			/* Only max_slave_count will be scanned in a search,
  			 * but it will start where it left off next search
  			 * until all ids are identified and then it will start
  			 * over.  A continued search will report the previous
  			 * last id as the first id (provided it is still on the
  			 * bus).
  			 */

  			dev_info(&dev->dev, "%s: max_slave_count %d reached, "

  				"will continue next search.
  ", __func__,

  				dev->max_slave_count);
  			set_bit(W1_WARN_MAX_COUNT, &dev->flags);
  		}

  	}
  }

  void w1_search_process_cb(struct w1_master *dev, u8 search_type,
  	w1_slave_found_callback cb)

  {
  	struct w1_slave *sl, *sln;

  	mutex_lock(&dev->list_mutex);

  	list_for_each_entry(sl, &dev->slist, w1_slave_entry)

  		clear_bit(W1_SLAVE_ACTIVE, &sl->flags);

  	mutex_unlock(&dev->list_mutex);

  	w1_search_devices(dev, search_type, cb);

  	mutex_lock(&dev->list_mutex);

  	list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {

  		if (!test_bit(W1_SLAVE_ACTIVE, &sl->flags) && !--sl->ttl) {
  			mutex_unlock(&dev->list_mutex);

  			w1_slave_detach(sl);

  			mutex_lock(&dev->list_mutex);
  		}

  		else if (test_bit(W1_SLAVE_ACTIVE, &sl->flags))

  			sl->ttl = dev->slave_ttl;
  	}

  	mutex_unlock(&dev->list_mutex);

  
  	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);
  }

  /**
   * w1_process_callbacks() - execute each dev->async_list callback entry
   * @dev: w1_master device
   *

   * The w1 master list_mutex must be held.
   *

   * Return: 1 if there were commands to executed 0 otherwise
   */

  int w1_process_callbacks(struct w1_master *dev)
  {
  	int ret = 0;
  	struct w1_async_cmd *async_cmd, *async_n;
  
  	/* The list can be added to in another thread, loop until it is empty */
  	while (!list_empty(&dev->async_list)) {
  		list_for_each_entry_safe(async_cmd, async_n, &dev->async_list,
  			async_entry) {
  			/* drop the lock, if it is a search it can take a long
  			 * time */
  			mutex_unlock(&dev->list_mutex);
  			async_cmd->cb(dev, async_cmd);
  			ret = 1;
  			mutex_lock(&dev->list_mutex);
  		}
  	}
  	return ret;
  }

  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 =
  	  usecs_to_jiffies(w1_timeout * 1000000 + w1_timeout_us);

  	/* remainder if it woke up early */
  	unsigned long jremain = 0;

  	for (;;) {
  
  		if (!jremain && dev->search_count) {

  			mutex_lock(&dev->mutex);
  			w1_search_process(dev, W1_SEARCH);
  			mutex_unlock(&dev->mutex);
  		}

  		mutex_lock(&dev->list_mutex);
  		/* Note, w1_process_callback drops the lock while processing,
  		 * but locks it again before returning.
  		 */
  		if (!w1_process_callbacks(dev) && jremain) {
  			/* a wake up is either to stop the thread, process
  			 * callbacks, or search, it isn't process callbacks, so
  			 * schedule a search.
  			 */
  			jremain = 1;
  		}

  		__set_current_state(TASK_INTERRUPTIBLE);

  		/* hold list_mutex until after interruptible to prevent loosing
  		 * the wakeup signal when async_cmd is added.
  		 */
  		mutex_unlock(&dev->list_mutex);

  		if (kthread_should_stop())
  			break;
  
  		/* Only sleep when the search is active. */

  		if (dev->search_count) {
  			if (!jremain)
  				jremain = jtime;
  			jremain = schedule_timeout(jremain);
  		}

  		else
  			schedule();

  	}
  
  	atomic_dec(&dev->refcnt);

  
  	return 0;
  }

  static int __init w1_init(void)

  {
  	int retval;

  	pr_info("Driver for 1-wire Dallas network protocol.
  ");

  	w1_init_netlink();

  	retval = bus_register(&w1_bus_type);
  	if (retval) {

  		pr_err("Failed to register bus. err=%d.
  ", retval);

  		goto err_out_exit_init;
  	}

  	retval = driver_register(&w1_master_driver);

  	if (retval) {

  		pr_err("Failed to register master driver. err=%d.
  ",

  			retval);
  		goto err_out_bus_unregister;
  	}

  	retval = driver_register(&w1_slave_driver);
  	if (retval) {

  		pr_err("Failed to register slave driver. err=%d.
  ",

  			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);

  
  MODULE_AUTHOR("Evgeniy Polyakov <zbr@ioremap.net>");
  MODULE_DESCRIPTION("Driver for 1-wire Dallas network protocol.");
  MODULE_LICENSE("GPL");