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
w1_alloc_dev(u32 id,int slave_count,int slave_ttl,struct device_driver * driver,struct device * device)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
w1_free_dev(struct w1_master * dev)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 */
w1_add_master_device(struct w1_bus_master * master)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
__w1_remove_master_device(struct w1_master * dev)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 */
w1_remove_master_device(struct w1_bus_master * bm)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