GNU Linux-libre 5.19-rc6-gnu
[releases.git] / drivers / w1 / w1_int.c
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);