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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net>
  */
 
 #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/of.h>
 
 #include <linux/atomic.h>
 
 #include "w1_internal.h"
 #include "w1_netlink.h"
 
 #define W1_FAMILY_DEFAULT   0
 #define W1_FAMILY_DS28E04       0x1C /* for crc quirk */
 
 
 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.\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 [%p]\n", __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\n", 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 const 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\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);
     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\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);
     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\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_timeout_us(struct device *dev,
     struct device_attribute *attr, char *buf)
 {
     ssize_t count;
     count = sprintf(buf, "%d\n", 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\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;
     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\n", sl->name);
     }
     if (!sl)
         c -= snprintf(buf + PAGE_SIZE - c, c, "not found.\n");
 
     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\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 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\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) {
         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\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_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.\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;
 }
 
 static int w1_family_notify(unsigned long action, struct w1_slave *sl)
 {
     const 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\n",
                     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\n",
                     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\n");
             } 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;
     sl->dev.of_node = of_find_matching_node(sl->master->dev.of_node,
                         sl->family->of_match_table);
 
     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);
 
     /* 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\n",
             dev_name(&sl->dev), err);
         put_device(&sl->dev);
         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.\n",
              __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\n",
           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.\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);
         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].\n", __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.\n", 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.\n", dev->name);
         mutex_unlock(&dev->list_mutex);
         mutex_unlock(&dev->mutex);
     }
     mutex_unlock(&w1_mlock);
 }
 
 static int w1_addr_crc_is_valid(struct w1_master *dev, u64 rn)
 {
     u64 rn_le = cpu_to_le64(rn);
     struct w1_reg_num *tmp = (struct w1_reg_num *)&rn;
     u8 crc;
 
     crc = w1_calc_crc8((u8 *)&rn_le, 7);
 
     /* quirk:
      *   DS28E04 (1w eeprom) has strapping pins to change
      *   address, but will not update the crc. So normal rules
      *   for consistent w1 addresses are violated. We test
      *   with the 7 LSBs of the address forced high.
      *
      *   (char*)&rn_le = { family, addr_lsb, ..., addr_msb, crc }.
      */
     if (crc != tmp->crc && tmp->family == W1_FAMILY_DS28E04) {
         u64 corr_le = rn_le;
 
         ((u8 *)&corr_le)[1] |= 0x7f;
         crc = w1_calc_crc8((u8 *)&corr_le, 7);
 
         dev_info(&dev->dev, "DS28E04 crc workaround on %02x.%012llx.%02x\n",
             tmp->family, (unsigned long long)tmp->id, tmp->crc);
     }
 
     if (crc != tmp->crc) {
         dev_dbg(&dev->dev, "w1 addr crc mismatch: %02x.%012llx.%02x != 0x%02x.\n",
             tmp->family, (unsigned long long)tmp->id, tmp->crc, crc);
         return 0;
     }
     return 1;
 }
 
 void w1_slave_found(struct w1_master *dev, u64 rn)
 {
     struct w1_slave *sl;
     struct w1_reg_num *tmp;
 
     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 && w1_addr_crc_is_valid(dev, rn))
             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.\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);
 
             /* 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\n");
                 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.\n", __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.\n");
 
     w1_init_netlink();
 
     retval = bus_register(&w1_bus_type);
     if (retval) {
         pr_err("Failed to register bus. err=%d.\n", retval);
         goto err_out_exit_init;
     }
 
     retval = driver_register(&w1_master_driver);
     if (retval) {
         pr_err("Failed to register master driver. err=%d.\n",
             retval);
         goto err_out_bus_unregister;
     }
 
     retval = driver_register(&w1_slave_driver);
     if (retval) {
         pr_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);
 
 MODULE_AUTHOR("Evgeniy Polyakov <zbr@ioremap.net>");
 MODULE_DESCRIPTION("Driver for 1-wire Dallas network protocol.");
 MODULE_LICENSE("GPL");

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