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