1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 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 18 static int w1_search_count = -1; /* Default is continual scan */ 19 module_param_named(search_count, w1_search_count, int, 0); 20 21 static int w1_enable_pullup = 1; 22 module_param_named(enable_pullup, w1_enable_pullup, int, 0); 23 24 static 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 pr_err("Failed to allocate %zd bytes for new w1 device.\n", 37 sizeof(struct w1_master)); 38 return NULL; 39 } 40 41 42 dev->bus_master = (struct w1_bus_master *)(dev + 1); 43 44 dev->owner = THIS_MODULE; 45 dev->max_slave_count = slave_count; 46 dev->slave_count = 0; 47 dev->attempts = 0; 48 dev->initialized = 0; 49 dev->id = id; 50 dev->slave_ttl = slave_ttl; 51 dev->search_count = w1_search_count; 52 dev->enable_pullup = w1_enable_pullup; 53 54 /* 1 for w1_process to decrement 55 * 1 for __w1_remove_master_device to decrement 56 */ 57 atomic_set(&dev->refcnt, 2); 58 59 INIT_LIST_HEAD(&dev->slist); 60 INIT_LIST_HEAD(&dev->async_list); 61 mutex_init(&dev->mutex); 62 mutex_init(&dev->bus_mutex); 63 mutex_init(&dev->list_mutex); 64 65 memcpy(&dev->dev, device, sizeof(struct device)); 66 dev_set_name(&dev->dev, "w1_bus_master%u", dev->id); 67 snprintf(dev->name, sizeof(dev->name), "w1_bus_master%u", dev->id); 68 dev->dev.init_name = dev->name; 69 70 dev->driver = driver; 71 72 dev->seq = 1; 73 74 err = device_register(&dev->dev); 75 if (err) { 76 pr_err("Failed to register master device. err=%d\n", err); 77 put_device(&dev->dev); 78 dev = NULL; 79 } 80 81 return dev; 82 } 83 84 static void w1_free_dev(struct w1_master *dev) 85 { 86 device_unregister(&dev->dev); 87 } 88 89 /** 90 * w1_add_master_device() - registers a new master device 91 * @master: master bus device to register 92 */ 93 int w1_add_master_device(struct w1_bus_master *master) 94 { 95 struct w1_master *dev, *entry; 96 int retval = 0; 97 struct w1_netlink_msg msg; 98 int id, found; 99 100 /* validate minimum functionality */ 101 if (!(master->touch_bit && master->reset_bus) && 102 !(master->write_bit && master->read_bit) && 103 !(master->write_byte && master->read_byte && master->reset_bus)) { 104 pr_err("w1_add_master_device: invalid function set\n"); 105 return(-EINVAL); 106 } 107 108 /* Lock until the device is added (or not) to w1_masters. */ 109 mutex_lock(&w1_mlock); 110 /* Search for the first available id (starting at 1). */ 111 id = 0; 112 do { 113 ++id; 114 found = 0; 115 list_for_each_entry(entry, &w1_masters, w1_master_entry) { 116 if (entry->id == id) { 117 found = 1; 118 break; 119 } 120 } 121 } while (found); 122 123 dev = w1_alloc_dev(id, w1_max_slave_count, w1_max_slave_ttl, 124 &w1_master_driver, &w1_master_device); 125 if (!dev) { 126 mutex_unlock(&w1_mlock); 127 return -ENOMEM; 128 } 129 130 retval = w1_create_master_attributes(dev); 131 if (retval) { 132 mutex_unlock(&w1_mlock); 133 goto err_out_free_dev; 134 } 135 136 memcpy(dev->bus_master, master, sizeof(struct w1_bus_master)); 137 138 dev->initialized = 1; 139 140 dev->thread = kthread_run(&w1_process, dev, "%s", dev->name); 141 if (IS_ERR(dev->thread)) { 142 retval = PTR_ERR(dev->thread); 143 dev_err(&dev->dev, 144 "Failed to create new kernel thread. err=%d\n", 145 retval); 146 mutex_unlock(&w1_mlock); 147 goto err_out_rm_attr; 148 } 149 150 list_add(&dev->w1_master_entry, &w1_masters); 151 mutex_unlock(&w1_mlock); 152 153 memset(&msg, 0, sizeof(msg)); 154 msg.id.mst.id = dev->id; 155 msg.type = W1_MASTER_ADD; 156 w1_netlink_send(dev, &msg); 157 158 return 0; 159 160 #if 0 /* Thread cleanup code, not required currently. */ 161 err_out_kill_thread: 162 set_bit(W1_ABORT_SEARCH, &dev->flags); 163 kthread_stop(dev->thread); 164 #endif 165 err_out_rm_attr: 166 w1_destroy_master_attributes(dev); 167 err_out_free_dev: 168 w1_free_dev(dev); 169 170 return retval; 171 } 172 EXPORT_SYMBOL(w1_add_master_device); 173 174 void __w1_remove_master_device(struct w1_master *dev) 175 { 176 struct w1_netlink_msg msg; 177 struct w1_slave *sl, *sln; 178 179 mutex_lock(&w1_mlock); 180 list_del(&dev->w1_master_entry); 181 mutex_unlock(&w1_mlock); 182 183 set_bit(W1_ABORT_SEARCH, &dev->flags); 184 kthread_stop(dev->thread); 185 186 mutex_lock(&dev->mutex); 187 mutex_lock(&dev->list_mutex); 188 list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) { 189 mutex_unlock(&dev->list_mutex); 190 w1_slave_detach(sl); 191 mutex_lock(&dev->list_mutex); 192 } 193 w1_destroy_master_attributes(dev); 194 mutex_unlock(&dev->list_mutex); 195 mutex_unlock(&dev->mutex); 196 atomic_dec(&dev->refcnt); 197 198 while (atomic_read(&dev->refcnt)) { 199 dev_info(&dev->dev, "Waiting for %s to become free: refcnt=%d.\n", 200 dev->name, atomic_read(&dev->refcnt)); 201 202 if (msleep_interruptible(1000)) 203 flush_signals(current); 204 mutex_lock(&dev->list_mutex); 205 w1_process_callbacks(dev); 206 mutex_unlock(&dev->list_mutex); 207 } 208 mutex_lock(&dev->list_mutex); 209 w1_process_callbacks(dev); 210 mutex_unlock(&dev->list_mutex); 211 212 memset(&msg, 0, sizeof(msg)); 213 msg.id.mst.id = dev->id; 214 msg.type = W1_MASTER_REMOVE; 215 w1_netlink_send(dev, &msg); 216 217 w1_free_dev(dev); 218 } 219 220 /** 221 * w1_remove_master_device() - unregister a master device 222 * @bm: master bus device to remove 223 */ 224 void w1_remove_master_device(struct w1_bus_master *bm) 225 { 226 struct w1_master *dev, *found = NULL; 227 228 list_for_each_entry(dev, &w1_masters, w1_master_entry) { 229 if (!dev->initialized) 230 continue; 231 232 if (dev->bus_master->data == bm->data) { 233 found = dev; 234 break; 235 } 236 } 237 238 if (!found) { 239 pr_err("Device doesn't exist.\n"); 240 return; 241 } 242 243 __w1_remove_master_device(found); 244 } 245 EXPORT_SYMBOL(w1_remove_master_device); 246