xref: /openbmc/linux/drivers/w1/w1_int.c (revision d2999e1b)
1 /*
2  *	w1_int.c
3  *
4  * Copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net>
5  *
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License as published by
9  * the Free Software Foundation; either version 2 of the License, or
10  * (at your option) any later version.
11  *
12  * This program is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15  * GNU General Public License for more details.
16  *
17  * You should have received a copy of the GNU General Public License
18  * along with this program; if not, write to the Free Software
19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20  */
21 
22 #include <linux/kernel.h>
23 #include <linux/list.h>
24 #include <linux/delay.h>
25 #include <linux/kthread.h>
26 #include <linux/slab.h>
27 #include <linux/export.h>
28 #include <linux/moduleparam.h>
29 
30 #include "w1.h"
31 #include "w1_log.h"
32 #include "w1_netlink.h"
33 #include "w1_int.h"
34 
35 static int w1_search_count = -1; /* Default is continual scan */
36 module_param_named(search_count, w1_search_count, int, 0);
37 
38 static int w1_enable_pullup = 1;
39 module_param_named(enable_pullup, w1_enable_pullup, int, 0);
40 
41 static struct w1_master * w1_alloc_dev(u32 id, int slave_count, int slave_ttl,
42 				       struct device_driver *driver,
43 				       struct device *device)
44 {
45 	struct w1_master *dev;
46 	int err;
47 
48 	/*
49 	 * We are in process context(kernel thread), so can sleep.
50 	 */
51 	dev = kzalloc(sizeof(struct w1_master) + sizeof(struct w1_bus_master), GFP_KERNEL);
52 	if (!dev) {
53 		printk(KERN_ERR
54 			"Failed to allocate %zd bytes for new w1 device.\n",
55 			sizeof(struct w1_master));
56 		return NULL;
57 	}
58 
59 
60 	dev->bus_master = (struct w1_bus_master *)(dev + 1);
61 
62 	dev->owner		= THIS_MODULE;
63 	dev->max_slave_count	= slave_count;
64 	dev->slave_count	= 0;
65 	dev->attempts		= 0;
66 	dev->initialized	= 0;
67 	dev->id			= id;
68 	dev->slave_ttl		= slave_ttl;
69 	dev->search_count	= w1_search_count;
70 	dev->enable_pullup	= w1_enable_pullup;
71 
72 	/* 1 for w1_process to decrement
73 	 * 1 for __w1_remove_master_device to decrement
74 	 */
75 	atomic_set(&dev->refcnt, 2);
76 
77 	INIT_LIST_HEAD(&dev->slist);
78 	INIT_LIST_HEAD(&dev->async_list);
79 	mutex_init(&dev->mutex);
80 	mutex_init(&dev->bus_mutex);
81 	mutex_init(&dev->list_mutex);
82 
83 	memcpy(&dev->dev, device, sizeof(struct device));
84 	dev_set_name(&dev->dev, "w1_bus_master%u", dev->id);
85 	snprintf(dev->name, sizeof(dev->name), "w1_bus_master%u", dev->id);
86 	dev->dev.init_name = dev->name;
87 
88 	dev->driver = driver;
89 
90 	dev->seq = 1;
91 
92 	err = device_register(&dev->dev);
93 	if (err) {
94 		printk(KERN_ERR "Failed to register master device. err=%d\n", err);
95 		memset(dev, 0, sizeof(struct w1_master));
96 		kfree(dev);
97 		dev = NULL;
98 	}
99 
100 	return dev;
101 }
102 
103 static void w1_free_dev(struct w1_master *dev)
104 {
105 	device_unregister(&dev->dev);
106 }
107 
108 /**
109  * w1_add_master_device() - registers a new master device
110  * @master:	master bus device to register
111  */
112 int w1_add_master_device(struct w1_bus_master *master)
113 {
114 	struct w1_master *dev, *entry;
115 	int retval = 0;
116 	struct w1_netlink_msg msg;
117 	int id, found;
118 
119         /* validate minimum functionality */
120         if (!(master->touch_bit && master->reset_bus) &&
121             !(master->write_bit && master->read_bit) &&
122 	    !(master->write_byte && master->read_byte && master->reset_bus)) {
123 		printk(KERN_ERR "w1_add_master_device: invalid function set\n");
124 		return(-EINVAL);
125         }
126 
127 	/* Lock until the device is added (or not) to w1_masters. */
128 	mutex_lock(&w1_mlock);
129 	/* Search for the first available id (starting at 1). */
130 	id = 0;
131 	do {
132 		++id;
133 		found = 0;
134 		list_for_each_entry(entry, &w1_masters, w1_master_entry) {
135 			if (entry->id == id) {
136 				found = 1;
137 				break;
138 			}
139 		}
140 	} while (found);
141 
142 	dev = w1_alloc_dev(id, w1_max_slave_count, w1_max_slave_ttl,
143 		&w1_master_driver, &w1_master_device);
144 	if (!dev) {
145 		mutex_unlock(&w1_mlock);
146 		return -ENOMEM;
147 	}
148 
149 	retval =  w1_create_master_attributes(dev);
150 	if (retval) {
151 		mutex_unlock(&w1_mlock);
152 		goto err_out_free_dev;
153 	}
154 
155 	memcpy(dev->bus_master, master, sizeof(struct w1_bus_master));
156 
157 	dev->initialized = 1;
158 
159 	dev->thread = kthread_run(&w1_process, dev, "%s", dev->name);
160 	if (IS_ERR(dev->thread)) {
161 		retval = PTR_ERR(dev->thread);
162 		dev_err(&dev->dev,
163 			 "Failed to create new kernel thread. err=%d\n",
164 			 retval);
165 		mutex_unlock(&w1_mlock);
166 		goto err_out_rm_attr;
167 	}
168 
169 	list_add(&dev->w1_master_entry, &w1_masters);
170 	mutex_unlock(&w1_mlock);
171 
172 	memset(&msg, 0, sizeof(msg));
173 	msg.id.mst.id = dev->id;
174 	msg.type = W1_MASTER_ADD;
175 	w1_netlink_send(dev, &msg);
176 
177 	return 0;
178 
179 #if 0 /* Thread cleanup code, not required currently. */
180 err_out_kill_thread:
181 	set_bit(W1_ABORT_SEARCH, &dev->flags);
182 	kthread_stop(dev->thread);
183 #endif
184 err_out_rm_attr:
185 	w1_destroy_master_attributes(dev);
186 err_out_free_dev:
187 	w1_free_dev(dev);
188 
189 	return retval;
190 }
191 
192 void __w1_remove_master_device(struct w1_master *dev)
193 {
194 	struct w1_netlink_msg msg;
195 	struct w1_slave *sl, *sln;
196 
197 	mutex_lock(&w1_mlock);
198 	list_del(&dev->w1_master_entry);
199 	mutex_unlock(&w1_mlock);
200 
201 	set_bit(W1_ABORT_SEARCH, &dev->flags);
202 	kthread_stop(dev->thread);
203 
204 	mutex_lock(&dev->mutex);
205 	mutex_lock(&dev->list_mutex);
206 	list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
207 		mutex_unlock(&dev->list_mutex);
208 		w1_slave_detach(sl);
209 		mutex_lock(&dev->list_mutex);
210 	}
211 	w1_destroy_master_attributes(dev);
212 	mutex_unlock(&dev->list_mutex);
213 	mutex_unlock(&dev->mutex);
214 	atomic_dec(&dev->refcnt);
215 
216 	while (atomic_read(&dev->refcnt)) {
217 		dev_info(&dev->dev, "Waiting for %s to become free: refcnt=%d.\n",
218 				dev->name, atomic_read(&dev->refcnt));
219 
220 		if (msleep_interruptible(1000))
221 			flush_signals(current);
222 		mutex_lock(&dev->list_mutex);
223 		w1_process_callbacks(dev);
224 		mutex_unlock(&dev->list_mutex);
225 	}
226 	mutex_lock(&dev->list_mutex);
227 	w1_process_callbacks(dev);
228 	mutex_unlock(&dev->list_mutex);
229 
230 	memset(&msg, 0, sizeof(msg));
231 	msg.id.mst.id = dev->id;
232 	msg.type = W1_MASTER_REMOVE;
233 	w1_netlink_send(dev, &msg);
234 
235 	w1_free_dev(dev);
236 }
237 
238 /**
239  * w1_remove_master_device() - unregister a master device
240  * @bm:	master bus device to remove
241  */
242 void w1_remove_master_device(struct w1_bus_master *bm)
243 {
244 	struct w1_master *dev, *found = NULL;
245 
246 	list_for_each_entry(dev, &w1_masters, w1_master_entry) {
247 		if (!dev->initialized)
248 			continue;
249 
250 		if (dev->bus_master->data == bm->data) {
251 			found = dev;
252 			break;
253 		}
254 	}
255 
256 	if (!found) {
257 		printk(KERN_ERR "Device doesn't exist.\n");
258 		return;
259 	}
260 
261 	__w1_remove_master_device(found);
262 }
263 
264 EXPORT_SYMBOL(w1_add_master_device);
265 EXPORT_SYMBOL(w1_remove_master_device);
266