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(size: 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(v: &dev->refcnt, i: 1); |
57 | |
58 | INIT_LIST_HEAD(list: &dev->slist); |
59 | INIT_LIST_HEAD(list: &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->dev, name: "w1_bus_master%u" , dev->id); |
66 | snprintf(buf: dev->name, size: sizeof(dev->name), fmt: "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->dev); |
74 | if (err) { |
75 | pr_err("Failed to register master device. err=%d\n" , err); |
76 | put_device(dev: &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->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, slave_count: w1_max_slave_count, slave_ttl: w1_max_slave_ttl, |
123 | driver: &w1_master_driver, device: &w1_master_device); |
124 | if (!dev) { |
125 | mutex_unlock(lock: &w1_mlock); |
126 | return -ENOMEM; |
127 | } |
128 | |
129 | retval = w1_create_master_attributes(master: dev); |
130 | if (retval) { |
131 | mutex_unlock(lock: &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(ptr: dev->thread)) { |
141 | retval = PTR_ERR(ptr: dev->thread); |
142 | dev_err(&dev->dev, |
143 | "Failed to create new kernel thread. err=%d\n" , |
144 | retval); |
145 | mutex_unlock(lock: &w1_mlock); |
146 | goto err_out_rm_attr; |
147 | } |
148 | |
149 | list_add(new: &dev->w1_master_entry, head: &w1_masters); |
150 | mutex_unlock(lock: &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(master: 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(entry: &dev->w1_master_entry); |
180 | mutex_unlock(lock: &w1_mlock); |
181 | |
182 | set_bit(nr: W1_ABORT_SEARCH, addr: &dev->flags); |
183 | kthread_stop(k: 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(lock: &dev->list_mutex); |
189 | w1_slave_detach(sl); |
190 | mutex_lock(&dev->list_mutex); |
191 | } |
192 | w1_destroy_master_attributes(master: dev); |
193 | mutex_unlock(lock: &dev->list_mutex); |
194 | mutex_unlock(lock: &dev->mutex); |
195 | atomic_dec(v: &dev->refcnt); |
196 | |
197 | while (atomic_read(v: &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(msecs: 1000)) |
202 | flush_signals(current); |
203 | mutex_lock(&dev->list_mutex); |
204 | w1_process_callbacks(dev); |
205 | mutex_unlock(lock: &dev->list_mutex); |
206 | } |
207 | mutex_lock(&dev->list_mutex); |
208 | w1_process_callbacks(dev); |
209 | mutex_unlock(lock: &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(dev: found); |
243 | } |
244 | EXPORT_SYMBOL(w1_remove_master_device); |
245 | |