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_internal.h" 25 #include "w1_netlink.h" 26 27 static int w1_search_count = -1; /* Default is continual scan */ 28 module_param_named(search_count, w1_search_count, int, 0); 29 30 static int w1_enable_pullup = 1; 31 module_param_named(enable_pullup, w1_enable_pullup, int, 0); 32 33 static struct w1_master *w1_alloc_dev(u32 id, int slave_count, int slave_ttl, 34 struct device_driver *driver, 35 struct device *device) 36 { 37 struct w1_master *dev; 38 int err; 39 40 /* 41 * We are in process context(kernel thread), so can sleep. 42 */ 43 dev = kzalloc(sizeof(struct w1_master) + sizeof(struct w1_bus_master), GFP_KERNEL); 44 if (!dev) { 45 pr_err("Failed to allocate %zd bytes for new w1 device.\n", 46 sizeof(struct w1_master)); 47 return NULL; 48 } 49 50 51 dev->bus_master = (struct w1_bus_master *)(dev + 1); 52 53 dev->owner = THIS_MODULE; 54 dev->max_slave_count = slave_count; 55 dev->slave_count = 0; 56 dev->attempts = 0; 57 dev->initialized = 0; 58 dev->id = id; 59 dev->slave_ttl = slave_ttl; 60 dev->search_count = w1_search_count; 61 dev->enable_pullup = w1_enable_pullup; 62 63 /* 1 for w1_process to decrement 64 * 1 for __w1_remove_master_device to decrement 65 */ 66 atomic_set(&dev->refcnt, 2); 67 68 INIT_LIST_HEAD(&dev->slist); 69 INIT_LIST_HEAD(&dev->async_list); 70 mutex_init(&dev->mutex); 71 mutex_init(&dev->bus_mutex); 72 mutex_init(&dev->list_mutex); 73 74 memcpy(&dev->dev, device, sizeof(struct device)); 75 dev_set_name(&dev->dev, "w1_bus_master%u", dev->id); 76 snprintf(dev->name, sizeof(dev->name), "w1_bus_master%u", dev->id); 77 dev->dev.init_name = dev->name; 78 79 dev->driver = driver; 80 81 dev->seq = 1; 82 83 err = device_register(&dev->dev); 84 if (err) { 85 pr_err("Failed to register master device. err=%d\n", err); 86 put_device(&dev->dev); 87 dev = NULL; 88 } 89 90 return dev; 91 } 92 93 static void w1_free_dev(struct w1_master *dev) 94 { 95 device_unregister(&dev->dev); 96 } 97 98 /** 99 * w1_add_master_device() - registers a new master device 100 * @master: master bus device to register 101 */ 102 int w1_add_master_device(struct w1_bus_master *master) 103 { 104 struct w1_master *dev, *entry; 105 int retval = 0; 106 struct w1_netlink_msg msg; 107 int id, found; 108 109 /* validate minimum functionality */ 110 if (!(master->touch_bit && master->reset_bus) && 111 !(master->write_bit && master->read_bit) && 112 !(master->write_byte && master->read_byte && master->reset_bus)) { 113 pr_err("w1_add_master_device: invalid function set\n"); 114 return(-EINVAL); 115 } 116 117 /* Lock until the device is added (or not) to w1_masters. */ 118 mutex_lock(&w1_mlock); 119 /* Search for the first available id (starting at 1). */ 120 id = 0; 121 do { 122 ++id; 123 found = 0; 124 list_for_each_entry(entry, &w1_masters, w1_master_entry) { 125 if (entry->id == id) { 126 found = 1; 127 break; 128 } 129 } 130 } while (found); 131 132 dev = w1_alloc_dev(id, w1_max_slave_count, w1_max_slave_ttl, 133 &w1_master_driver, &w1_master_device); 134 if (!dev) { 135 mutex_unlock(&w1_mlock); 136 return -ENOMEM; 137 } 138 139 retval = w1_create_master_attributes(dev); 140 if (retval) { 141 mutex_unlock(&w1_mlock); 142 goto err_out_free_dev; 143 } 144 145 memcpy(dev->bus_master, master, sizeof(struct w1_bus_master)); 146 147 dev->initialized = 1; 148 149 dev->thread = kthread_run(&w1_process, dev, "%s", dev->name); 150 if (IS_ERR(dev->thread)) { 151 retval = PTR_ERR(dev->thread); 152 dev_err(&dev->dev, 153 "Failed to create new kernel thread. err=%d\n", 154 retval); 155 mutex_unlock(&w1_mlock); 156 goto err_out_rm_attr; 157 } 158 159 list_add(&dev->w1_master_entry, &w1_masters); 160 mutex_unlock(&w1_mlock); 161 162 memset(&msg, 0, sizeof(msg)); 163 msg.id.mst.id = dev->id; 164 msg.type = W1_MASTER_ADD; 165 w1_netlink_send(dev, &msg); 166 167 return 0; 168 169 #if 0 /* Thread cleanup code, not required currently. */ 170 err_out_kill_thread: 171 set_bit(W1_ABORT_SEARCH, &dev->flags); 172 kthread_stop(dev->thread); 173 #endif 174 err_out_rm_attr: 175 w1_destroy_master_attributes(dev); 176 err_out_free_dev: 177 w1_free_dev(dev); 178 179 return retval; 180 } 181 EXPORT_SYMBOL(w1_add_master_device); 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 EXPORT_SYMBOL(w1_remove_master_device); 255