1 /* 2 * Copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net> 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License as published by 6 * the Free Software Foundation; either version 2 of the License, or 7 * (at your option) any later version. 8 * 9 * This program is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 * GNU General Public License for more details. 13 */ 14 15 #include <linux/kernel.h> 16 #include <linux/list.h> 17 #include <linux/delay.h> 18 #include <linux/kthread.h> 19 #include <linux/slab.h> 20 #include <linux/sched/signal.h> 21 #include <linux/export.h> 22 #include <linux/moduleparam.h> 23 24 #include "w1.h" 25 #include "w1_log.h" 26 #include "w1_netlink.h" 27 #include "w1_int.h" 28 29 static int w1_search_count = -1; /* Default is continual scan */ 30 module_param_named(search_count, w1_search_count, int, 0); 31 32 static int w1_enable_pullup = 1; 33 module_param_named(enable_pullup, w1_enable_pullup, int, 0); 34 35 static struct w1_master *w1_alloc_dev(u32 id, int slave_count, int slave_ttl, 36 struct device_driver *driver, 37 struct device *device) 38 { 39 struct w1_master *dev; 40 int err; 41 42 /* 43 * We are in process context(kernel thread), so can sleep. 44 */ 45 dev = kzalloc(sizeof(struct w1_master) + sizeof(struct w1_bus_master), GFP_KERNEL); 46 if (!dev) { 47 pr_err("Failed to allocate %zd bytes for new w1 device.\n", 48 sizeof(struct w1_master)); 49 return NULL; 50 } 51 52 53 dev->bus_master = (struct w1_bus_master *)(dev + 1); 54 55 dev->owner = THIS_MODULE; 56 dev->max_slave_count = slave_count; 57 dev->slave_count = 0; 58 dev->attempts = 0; 59 dev->initialized = 0; 60 dev->id = id; 61 dev->slave_ttl = slave_ttl; 62 dev->search_count = w1_search_count; 63 dev->enable_pullup = w1_enable_pullup; 64 65 /* 1 for w1_process to decrement 66 * 1 for __w1_remove_master_device to decrement 67 */ 68 atomic_set(&dev->refcnt, 2); 69 70 INIT_LIST_HEAD(&dev->slist); 71 INIT_LIST_HEAD(&dev->async_list); 72 mutex_init(&dev->mutex); 73 mutex_init(&dev->bus_mutex); 74 mutex_init(&dev->list_mutex); 75 76 memcpy(&dev->dev, device, sizeof(struct device)); 77 dev_set_name(&dev->dev, "w1_bus_master%u", dev->id); 78 snprintf(dev->name, sizeof(dev->name), "w1_bus_master%u", dev->id); 79 dev->dev.init_name = dev->name; 80 81 dev->driver = driver; 82 83 dev->seq = 1; 84 85 err = device_register(&dev->dev); 86 if (err) { 87 pr_err("Failed to register master device. err=%d\n", err); 88 put_device(&dev->dev); 89 dev = NULL; 90 } 91 92 return dev; 93 } 94 95 static void w1_free_dev(struct w1_master *dev) 96 { 97 device_unregister(&dev->dev); 98 } 99 100 /** 101 * w1_add_master_device() - registers a new master device 102 * @master: master bus device to register 103 */ 104 int w1_add_master_device(struct w1_bus_master *master) 105 { 106 struct w1_master *dev, *entry; 107 int retval = 0; 108 struct w1_netlink_msg msg; 109 int id, found; 110 111 /* validate minimum functionality */ 112 if (!(master->touch_bit && master->reset_bus) && 113 !(master->write_bit && master->read_bit) && 114 !(master->write_byte && master->read_byte && master->reset_bus)) { 115 pr_err("w1_add_master_device: invalid function set\n"); 116 return(-EINVAL); 117 } 118 119 /* Lock until the device is added (or not) to w1_masters. */ 120 mutex_lock(&w1_mlock); 121 /* Search for the first available id (starting at 1). */ 122 id = 0; 123 do { 124 ++id; 125 found = 0; 126 list_for_each_entry(entry, &w1_masters, w1_master_entry) { 127 if (entry->id == id) { 128 found = 1; 129 break; 130 } 131 } 132 } while (found); 133 134 dev = w1_alloc_dev(id, w1_max_slave_count, w1_max_slave_ttl, 135 &w1_master_driver, &w1_master_device); 136 if (!dev) { 137 mutex_unlock(&w1_mlock); 138 return -ENOMEM; 139 } 140 141 retval = w1_create_master_attributes(dev); 142 if (retval) { 143 mutex_unlock(&w1_mlock); 144 goto err_out_free_dev; 145 } 146 147 memcpy(dev->bus_master, master, sizeof(struct w1_bus_master)); 148 149 dev->initialized = 1; 150 151 dev->thread = kthread_run(&w1_process, dev, "%s", dev->name); 152 if (IS_ERR(dev->thread)) { 153 retval = PTR_ERR(dev->thread); 154 dev_err(&dev->dev, 155 "Failed to create new kernel thread. err=%d\n", 156 retval); 157 mutex_unlock(&w1_mlock); 158 goto err_out_rm_attr; 159 } 160 161 list_add(&dev->w1_master_entry, &w1_masters); 162 mutex_unlock(&w1_mlock); 163 164 memset(&msg, 0, sizeof(msg)); 165 msg.id.mst.id = dev->id; 166 msg.type = W1_MASTER_ADD; 167 w1_netlink_send(dev, &msg); 168 169 return 0; 170 171 #if 0 /* Thread cleanup code, not required currently. */ 172 err_out_kill_thread: 173 set_bit(W1_ABORT_SEARCH, &dev->flags); 174 kthread_stop(dev->thread); 175 #endif 176 err_out_rm_attr: 177 w1_destroy_master_attributes(dev); 178 err_out_free_dev: 179 w1_free_dev(dev); 180 181 return retval; 182 } 183 184 void __w1_remove_master_device(struct w1_master *dev) 185 { 186 struct w1_netlink_msg msg; 187 struct w1_slave *sl, *sln; 188 189 mutex_lock(&w1_mlock); 190 list_del(&dev->w1_master_entry); 191 mutex_unlock(&w1_mlock); 192 193 set_bit(W1_ABORT_SEARCH, &dev->flags); 194 kthread_stop(dev->thread); 195 196 mutex_lock(&dev->mutex); 197 mutex_lock(&dev->list_mutex); 198 list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) { 199 mutex_unlock(&dev->list_mutex); 200 w1_slave_detach(sl); 201 mutex_lock(&dev->list_mutex); 202 } 203 w1_destroy_master_attributes(dev); 204 mutex_unlock(&dev->list_mutex); 205 mutex_unlock(&dev->mutex); 206 atomic_dec(&dev->refcnt); 207 208 while (atomic_read(&dev->refcnt)) { 209 dev_info(&dev->dev, "Waiting for %s to become free: refcnt=%d.\n", 210 dev->name, atomic_read(&dev->refcnt)); 211 212 if (msleep_interruptible(1000)) 213 flush_signals(current); 214 mutex_lock(&dev->list_mutex); 215 w1_process_callbacks(dev); 216 mutex_unlock(&dev->list_mutex); 217 } 218 mutex_lock(&dev->list_mutex); 219 w1_process_callbacks(dev); 220 mutex_unlock(&dev->list_mutex); 221 222 memset(&msg, 0, sizeof(msg)); 223 msg.id.mst.id = dev->id; 224 msg.type = W1_MASTER_REMOVE; 225 w1_netlink_send(dev, &msg); 226 227 w1_free_dev(dev); 228 } 229 230 /** 231 * w1_remove_master_device() - unregister a master device 232 * @bm: master bus device to remove 233 */ 234 void w1_remove_master_device(struct w1_bus_master *bm) 235 { 236 struct w1_master *dev, *found = NULL; 237 238 list_for_each_entry(dev, &w1_masters, w1_master_entry) { 239 if (!dev->initialized) 240 continue; 241 242 if (dev->bus_master->data == bm->data) { 243 found = dev; 244 break; 245 } 246 } 247 248 if (!found) { 249 pr_err("Device doesn't exist.\n"); 250 return; 251 } 252 253 __w1_remove_master_device(found); 254 } 255 256 EXPORT_SYMBOL(w1_add_master_device); 257 EXPORT_SYMBOL(w1_remove_master_device); 258