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