xref: /openbmc/linux/drivers/w1/w1_int.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
1 /*
2  *	w1_int.c
3  *
4  * Copyright (c) 2004 Evgeniy Polyakov <johnpol@2ka.mipt.ru>
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 
26 #include "w1.h"
27 #include "w1_log.h"
28 #include "w1_netlink.h"
29 
30 static u32 w1_ids = 1;
31 
32 extern struct device_driver w1_master_driver;
33 extern struct bus_type w1_bus_type;
34 extern struct device w1_master_device;
35 extern int w1_max_slave_count;
36 extern int w1_max_slave_ttl;
37 extern struct list_head w1_masters;
38 extern spinlock_t w1_mlock;
39 
40 extern int w1_process(void *);
41 
42 static struct w1_master * w1_alloc_dev(u32 id, int slave_count, int slave_ttl,
43 				       struct device_driver *driver,
44 				       struct device *device)
45 {
46 	struct w1_master *dev;
47 	int err;
48 
49 	/*
50 	 * We are in process context(kernel thread), so can sleep.
51 	 */
52 	dev = kmalloc(sizeof(struct w1_master) + sizeof(struct w1_bus_master), GFP_KERNEL);
53 	if (!dev) {
54 		printk(KERN_ERR
55 			"Failed to allocate %zd bytes for new w1 device.\n",
56 			sizeof(struct w1_master));
57 		return NULL;
58 	}
59 
60 	memset(dev, 0, sizeof(struct w1_master) + sizeof(struct w1_bus_master));
61 
62 	dev->bus_master = (struct w1_bus_master *)(dev + 1);
63 
64 	dev->owner		= THIS_MODULE;
65 	dev->max_slave_count	= slave_count;
66 	dev->slave_count	= 0;
67 	dev->attempts		= 0;
68 	dev->kpid		= -1;
69 	dev->initialized	= 0;
70 	dev->id			= id;
71 	dev->slave_ttl		= slave_ttl;
72         dev->search_count	= -1; /* continual scan */
73 
74 	atomic_set(&dev->refcnt, 2);
75 
76 	INIT_LIST_HEAD(&dev->slist);
77 	init_MUTEX(&dev->mutex);
78 
79 	init_completion(&dev->dev_exited);
80 
81 	memcpy(&dev->dev, device, sizeof(struct device));
82 	snprintf(dev->dev.bus_id, sizeof(dev->dev.bus_id),
83 		  "w1_bus_master%u", dev->id);
84 	snprintf(dev->name, sizeof(dev->name), "w1_bus_master%u", dev->id);
85 
86 	dev->driver = driver;
87 
88 	dev->groups = 1;
89 	dev->seq = 1;
90 	dev_init_netlink(dev);
91 
92 	err = device_register(&dev->dev);
93 	if (err) {
94 		printk(KERN_ERR "Failed to register master device. err=%d\n", err);
95 
96 		dev_fini_netlink(dev);
97 
98 		memset(dev, 0, sizeof(struct w1_master));
99 		kfree(dev);
100 		dev = NULL;
101 	}
102 
103 	return dev;
104 }
105 
106 void w1_free_dev(struct w1_master *dev)
107 {
108 	device_unregister(&dev->dev);
109 }
110 
111 int w1_add_master_device(struct w1_bus_master *master)
112 {
113 	struct w1_master *dev;
114 	int retval = 0;
115 	struct w1_netlink_msg msg;
116 
117         /* validate minimum functionality */
118         if (!(master->touch_bit && master->reset_bus) &&
119             !(master->write_bit && master->read_bit)) {
120 		printk(KERN_ERR "w1_add_master_device: invalid function set\n");
121 		return(-EINVAL);
122         }
123 
124 	dev = w1_alloc_dev(w1_ids++, w1_max_slave_count, w1_max_slave_ttl, &w1_master_driver, &w1_master_device);
125 	if (!dev)
126 		return -ENOMEM;
127 
128 	dev->kpid = kernel_thread(&w1_process, dev, 0);
129 	if (dev->kpid < 0) {
130 		dev_err(&dev->dev,
131 			 "Failed to create new kernel thread. err=%d\n",
132 			 dev->kpid);
133 		retval = dev->kpid;
134 		goto err_out_free_dev;
135 	}
136 
137 	retval =  w1_create_master_attributes(dev);
138 	if (retval)
139 		goto err_out_kill_thread;
140 
141 	memcpy(dev->bus_master, master, sizeof(struct w1_bus_master));
142 
143 	dev->initialized = 1;
144 
145 	spin_lock(&w1_mlock);
146 	list_add(&dev->w1_master_entry, &w1_masters);
147 	spin_unlock(&w1_mlock);
148 
149 	msg.id.mst.id = dev->id;
150 	msg.id.mst.pid = dev->kpid;
151 	msg.type = W1_MASTER_ADD;
152 	w1_netlink_send(dev, &msg);
153 
154 	return 0;
155 
156 err_out_kill_thread:
157 	set_bit(W1_MASTER_NEED_EXIT, &dev->flags);
158 	if (kill_proc(dev->kpid, SIGTERM, 1))
159 		dev_err(&dev->dev,
160 			 "Failed to send signal to w1 kernel thread %d.\n",
161 			 dev->kpid);
162 	wait_for_completion(&dev->dev_exited);
163 
164 err_out_free_dev:
165 	w1_free_dev(dev);
166 
167 	return retval;
168 }
169 
170 void __w1_remove_master_device(struct w1_master *dev)
171 {
172 	int err;
173 	struct w1_netlink_msg msg;
174 
175 	set_bit(W1_MASTER_NEED_EXIT, &dev->flags);
176 	err = kill_proc(dev->kpid, SIGTERM, 1);
177 	if (err)
178 		dev_err(&dev->dev,
179 			 "%s: Failed to send signal to w1 kernel thread %d.\n",
180 			 __func__, dev->kpid);
181 
182 	while (atomic_read(&dev->refcnt)) {
183 		dev_dbg(&dev->dev, "Waiting for %s to become free: refcnt=%d.\n",
184 				dev->name, atomic_read(&dev->refcnt));
185 
186 		if (msleep_interruptible(1000))
187 			flush_signals(current);
188 	}
189 
190 	msg.id.mst.id = dev->id;
191 	msg.id.mst.pid = dev->kpid;
192 	msg.type = W1_MASTER_REMOVE;
193 	w1_netlink_send(dev, &msg);
194 
195 	w1_free_dev(dev);
196 }
197 
198 void w1_remove_master_device(struct w1_bus_master *bm)
199 {
200 	struct w1_master *dev = NULL;
201 
202 	list_for_each_entry(dev, &w1_masters, w1_master_entry) {
203 		if (!dev->initialized)
204 			continue;
205 
206 		if (dev->bus_master->data == bm->data)
207 			break;
208 	}
209 
210 	if (!dev) {
211 		printk(KERN_ERR "Device doesn't exist.\n");
212 		return;
213 	}
214 
215 	__w1_remove_master_device(dev);
216 }
217 
218 EXPORT_SYMBOL(w1_add_master_device);
219 EXPORT_SYMBOL(w1_remove_master_device);
220 
221 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_W1);
222