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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * Copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net>4 */5 6#include <linux/kernel.h>7#include <linux/list.h>8#include <linux/delay.h>9#include <linux/kthread.h>10#include <linux/slab.h>11#include <linux/sched/signal.h>12#include <linux/export.h>13#include <linux/moduleparam.h>14 15#include "w1_internal.h"16#include "w1_netlink.h"17 18static int w1_search_count = -1; /* Default is continual scan */19module_param_named(search_count, w1_search_count, int, 0);20 21static int w1_enable_pullup = 1;22module_param_named(enable_pullup, w1_enable_pullup, int, 0);23 24static struct w1_master *w1_alloc_dev(u32 id, int slave_count, int slave_ttl,25 struct device_driver *driver,26 struct device *device)27{28 struct w1_master *dev;29 int err;30 31 /*32 * We are in process context(kernel thread), so can sleep.33 */34 dev = kzalloc(sizeof(struct w1_master) + sizeof(struct w1_bus_master), GFP_KERNEL);35 if (!dev)36 return NULL;37 38 dev->bus_master = (struct w1_bus_master *)(dev + 1);39 40 dev->owner = THIS_MODULE;41 dev->max_slave_count = slave_count;42 dev->slave_count = 0;43 dev->attempts = 0;44 dev->initialized = 0;45 dev->id = id;46 dev->slave_ttl = slave_ttl;47 dev->search_count = w1_search_count;48 dev->enable_pullup = w1_enable_pullup;49 50 /* For __w1_remove_master_device to decrement51 */52 atomic_set(&dev->refcnt, 1);53 54 INIT_LIST_HEAD(&dev->slist);55 INIT_LIST_HEAD(&dev->async_list);56 mutex_init(&dev->mutex);57 mutex_init(&dev->bus_mutex);58 mutex_init(&dev->list_mutex);59 60 memcpy(&dev->dev, device, sizeof(struct device));61 dev_set_name(&dev->dev, "w1_bus_master%u", dev->id);62 snprintf(dev->name, sizeof(dev->name), "w1_bus_master%u", dev->id);63 dev->dev.init_name = dev->name;64 65 dev->driver = driver;66 67 dev->seq = 1;68 69 err = device_register(&dev->dev);70 if (err) {71 pr_err("Failed to register master device. err=%d\n", err);72 put_device(&dev->dev);73 dev = NULL;74 }75 76 return dev;77}78 79static void w1_free_dev(struct w1_master *dev)80{81 device_unregister(&dev->dev);82}83 84/**85 * w1_add_master_device() - registers a new master device86 * @master: master bus device to register87 */88int w1_add_master_device(struct w1_bus_master *master)89{90 struct w1_master *dev, *entry;91 int retval = 0;92 struct w1_netlink_msg msg;93 int id, found;94 95 /* validate minimum functionality */96 if (!(master->touch_bit && master->reset_bus) &&97 !(master->write_bit && master->read_bit) &&98 !(master->write_byte && master->read_byte && master->reset_bus)) {99 pr_err("w1_add_master_device: invalid function set\n");100 return(-EINVAL);101 }102 103 /* Lock until the device is added (or not) to w1_masters. */104 mutex_lock(&w1_mlock);105 /* Search for the first available id (starting at 1). */106 id = 0;107 do {108 ++id;109 found = 0;110 list_for_each_entry(entry, &w1_masters, w1_master_entry) {111 if (entry->id == id) {112 found = 1;113 break;114 }115 }116 } while (found);117 118 dev = w1_alloc_dev(id, w1_max_slave_count, w1_max_slave_ttl,119 &w1_master_driver, &w1_master_device);120 if (!dev) {121 mutex_unlock(&w1_mlock);122 return -ENOMEM;123 }124 125 retval = w1_create_master_attributes(dev);126 if (retval) {127 mutex_unlock(&w1_mlock);128 goto err_out_free_dev;129 }130 131 memcpy(dev->bus_master, master, sizeof(struct w1_bus_master));132 133 dev->initialized = 1;134 135 dev->thread = kthread_run(&w1_process, dev, "%s", dev->name);136 if (IS_ERR(dev->thread)) {137 retval = PTR_ERR(dev->thread);138 dev_err(&dev->dev,139 "Failed to create new kernel thread. err=%d\n",140 retval);141 mutex_unlock(&w1_mlock);142 goto err_out_rm_attr;143 }144 145 list_add(&dev->w1_master_entry, &w1_masters);146 mutex_unlock(&w1_mlock);147 148 memset(&msg, 0, sizeof(msg));149 msg.id.mst.id = dev->id;150 msg.type = W1_MASTER_ADD;151 w1_netlink_send(dev, &msg);152 153 return 0;154 155#if 0 /* Thread cleanup code, not required currently. */156err_out_kill_thread:157 set_bit(W1_ABORT_SEARCH, &dev->flags);158 kthread_stop(dev->thread);159#endif160err_out_rm_attr:161 w1_destroy_master_attributes(dev);162err_out_free_dev:163 w1_free_dev(dev);164 165 return retval;166}167EXPORT_SYMBOL(w1_add_master_device);168 169void __w1_remove_master_device(struct w1_master *dev)170{171 struct w1_netlink_msg msg;172 struct w1_slave *sl, *sln;173 174 mutex_lock(&w1_mlock);175 list_del(&dev->w1_master_entry);176 mutex_unlock(&w1_mlock);177 178 set_bit(W1_ABORT_SEARCH, &dev->flags);179 kthread_stop(dev->thread);180 181 mutex_lock(&dev->mutex);182 mutex_lock(&dev->list_mutex);183 list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {184 mutex_unlock(&dev->list_mutex);185 w1_slave_detach(sl);186 mutex_lock(&dev->list_mutex);187 }188 w1_destroy_master_attributes(dev);189 mutex_unlock(&dev->list_mutex);190 mutex_unlock(&dev->mutex);191 atomic_dec(&dev->refcnt);192 193 while (atomic_read(&dev->refcnt)) {194 dev_info(&dev->dev, "Waiting for %s to become free: refcnt=%d.\n",195 dev->name, atomic_read(&dev->refcnt));196 197 if (msleep_interruptible(1000))198 flush_signals(current);199 mutex_lock(&dev->list_mutex);200 w1_process_callbacks(dev);201 mutex_unlock(&dev->list_mutex);202 }203 mutex_lock(&dev->list_mutex);204 w1_process_callbacks(dev);205 mutex_unlock(&dev->list_mutex);206 207 memset(&msg, 0, sizeof(msg));208 msg.id.mst.id = dev->id;209 msg.type = W1_MASTER_REMOVE;210 w1_netlink_send(dev, &msg);211 212 w1_free_dev(dev);213}214 215/**216 * w1_remove_master_device() - unregister a master device217 * @bm: master bus device to remove218 */219void w1_remove_master_device(struct w1_bus_master *bm)220{221 struct w1_master *dev, *found = NULL;222 223 list_for_each_entry(dev, &w1_masters, w1_master_entry) {224 if (!dev->initialized)225 continue;226 227 if (dev->bus_master->data == bm->data) {228 found = dev;229 break;230 }231 }232 233 if (!found) {234 pr_err("Device doesn't exist.\n");235 return;236 }237 238 __w1_remove_master_device(found);239}240EXPORT_SYMBOL(w1_remove_master_device);241