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