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 	/* 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 
w1_free_dev(struct w1_master * dev)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  */
w1_add_master_device(struct w1_bus_master * master)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 
__w1_remove_master_device(struct w1_master * dev)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  */
w1_remove_master_device(struct w1_bus_master * bm)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);
246