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_netlink.h" 26 #include "w1_int.h" 27 28 static int w1_search_count = -1; /* Default is continual scan */ 29 module_param_named(search_count, w1_search_count, int, 0); 30 31 static int w1_enable_pullup = 1; 32 module_param_named(enable_pullup, w1_enable_pullup, int, 0); 33 34 static struct w1_master *w1_alloc_dev(u32 id, int slave_count, int slave_ttl, 35 struct device_driver *driver, 36 struct device *device) 37 { 38 struct w1_master *dev; 39 int err; 40 41 /* 42 * We are in process context(kernel thread), so can sleep. 43 */ 44 dev = kzalloc(sizeof(struct w1_master) + sizeof(struct w1_bus_master), GFP_KERNEL); 45 if (!dev) { 46 pr_err("Failed to allocate %zd bytes for new w1 device.\n", 47 sizeof(struct w1_master)); 48 return NULL; 49 } 50 51 52 dev->bus_master = (struct w1_bus_master *)(dev + 1); 53 54 dev->owner = THIS_MODULE; 55 dev->max_slave_count = slave_count; 56 dev->slave_count = 0; 57 dev->attempts = 0; 58 dev->initialized = 0; 59 dev->id = id; 60 dev->slave_ttl = slave_ttl; 61 dev->search_count = w1_search_count; 62 dev->enable_pullup = w1_enable_pullup; 63 64 /* 1 for w1_process to decrement 65 * 1 for __w1_remove_master_device to decrement 66 */ 67 atomic_set(&dev->refcnt, 2); 68 69 INIT_LIST_HEAD(&dev->slist); 70 INIT_LIST_HEAD(&dev->async_list); 71 mutex_init(&dev->mutex); 72 mutex_init(&dev->bus_mutex); 73 mutex_init(&dev->list_mutex); 74 75 memcpy(&dev->dev, device, sizeof(struct device)); 76 dev_set_name(&dev->dev, "w1_bus_master%u", dev->id); 77 snprintf(dev->name, sizeof(dev->name), "w1_bus_master%u", dev->id); 78 dev->dev.init_name = dev->name; 79 80 dev->driver = driver; 81 82 dev->seq = 1; 83 84 err = device_register(&dev->dev); 85 if (err) { 86 pr_err("Failed to register master device. err=%d\n", err); 87 put_device(&dev->dev); 88 dev = NULL; 89 } 90 91 return dev; 92 } 93 94 static void w1_free_dev(struct w1_master *dev) 95 { 96 device_unregister(&dev->dev); 97 } 98 99 /** 100 * w1_add_master_device() - registers a new master device 101 * @master: master bus device to register 102 */ 103 int w1_add_master_device(struct w1_bus_master *master) 104 { 105 struct w1_master *dev, *entry; 106 int retval = 0; 107 struct w1_netlink_msg msg; 108 int id, found; 109 110 /* validate minimum functionality */ 111 if (!(master->touch_bit && master->reset_bus) && 112 !(master->write_bit && master->read_bit) && 113 !(master->write_byte && master->read_byte && master->reset_bus)) { 114 pr_err("w1_add_master_device: invalid function set\n"); 115 return(-EINVAL); 116 } 117 118 /* Lock until the device is added (or not) to w1_masters. */ 119 mutex_lock(&w1_mlock); 120 /* Search for the first available id (starting at 1). */ 121 id = 0; 122 do { 123 ++id; 124 found = 0; 125 list_for_each_entry(entry, &w1_masters, w1_master_entry) { 126 if (entry->id == id) { 127 found = 1; 128 break; 129 } 130 } 131 } while (found); 132 133 dev = w1_alloc_dev(id, w1_max_slave_count, w1_max_slave_ttl, 134 &w1_master_driver, &w1_master_device); 135 if (!dev) { 136 mutex_unlock(&w1_mlock); 137 return -ENOMEM; 138 } 139 140 retval = w1_create_master_attributes(dev); 141 if (retval) { 142 mutex_unlock(&w1_mlock); 143 goto err_out_free_dev; 144 } 145 146 memcpy(dev->bus_master, master, sizeof(struct w1_bus_master)); 147 148 dev->initialized = 1; 149 150 dev->thread = kthread_run(&w1_process, dev, "%s", dev->name); 151 if (IS_ERR(dev->thread)) { 152 retval = PTR_ERR(dev->thread); 153 dev_err(&dev->dev, 154 "Failed to create new kernel thread. err=%d\n", 155 retval); 156 mutex_unlock(&w1_mlock); 157 goto err_out_rm_attr; 158 } 159 160 list_add(&dev->w1_master_entry, &w1_masters); 161 mutex_unlock(&w1_mlock); 162 163 memset(&msg, 0, sizeof(msg)); 164 msg.id.mst.id = dev->id; 165 msg.type = W1_MASTER_ADD; 166 w1_netlink_send(dev, &msg); 167 168 return 0; 169 170 #if 0 /* Thread cleanup code, not required currently. */ 171 err_out_kill_thread: 172 set_bit(W1_ABORT_SEARCH, &dev->flags); 173 kthread_stop(dev->thread); 174 #endif 175 err_out_rm_attr: 176 w1_destroy_master_attributes(dev); 177 err_out_free_dev: 178 w1_free_dev(dev); 179 180 return retval; 181 } 182 183 void __w1_remove_master_device(struct w1_master *dev) 184 { 185 struct w1_netlink_msg msg; 186 struct w1_slave *sl, *sln; 187 188 mutex_lock(&w1_mlock); 189 list_del(&dev->w1_master_entry); 190 mutex_unlock(&w1_mlock); 191 192 set_bit(W1_ABORT_SEARCH, &dev->flags); 193 kthread_stop(dev->thread); 194 195 mutex_lock(&dev->mutex); 196 mutex_lock(&dev->list_mutex); 197 list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) { 198 mutex_unlock(&dev->list_mutex); 199 w1_slave_detach(sl); 200 mutex_lock(&dev->list_mutex); 201 } 202 w1_destroy_master_attributes(dev); 203 mutex_unlock(&dev->list_mutex); 204 mutex_unlock(&dev->mutex); 205 atomic_dec(&dev->refcnt); 206 207 while (atomic_read(&dev->refcnt)) { 208 dev_info(&dev->dev, "Waiting for %s to become free: refcnt=%d.\n", 209 dev->name, atomic_read(&dev->refcnt)); 210 211 if (msleep_interruptible(1000)) 212 flush_signals(current); 213 mutex_lock(&dev->list_mutex); 214 w1_process_callbacks(dev); 215 mutex_unlock(&dev->list_mutex); 216 } 217 mutex_lock(&dev->list_mutex); 218 w1_process_callbacks(dev); 219 mutex_unlock(&dev->list_mutex); 220 221 memset(&msg, 0, sizeof(msg)); 222 msg.id.mst.id = dev->id; 223 msg.type = W1_MASTER_REMOVE; 224 w1_netlink_send(dev, &msg); 225 226 w1_free_dev(dev); 227 } 228 229 /** 230 * w1_remove_master_device() - unregister a master device 231 * @bm: master bus device to remove 232 */ 233 void w1_remove_master_device(struct w1_bus_master *bm) 234 { 235 struct w1_master *dev, *found = NULL; 236 237 list_for_each_entry(dev, &w1_masters, w1_master_entry) { 238 if (!dev->initialized) 239 continue; 240 241 if (dev->bus_master->data == bm->data) { 242 found = dev; 243 break; 244 } 245 } 246 247 if (!found) { 248 pr_err("Device doesn't exist.\n"); 249 return; 250 } 251 252 __w1_remove_master_device(found); 253 } 254 255 EXPORT_SYMBOL(w1_add_master_device); 256 EXPORT_SYMBOL(w1_remove_master_device); 257