9d723efdf91543f9a7d650ae37e5662e137845e4
[linux-2.6.git] / drivers / w1 / w1_int.c
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 #include <linux/kthread.h>
26
27 #include "w1.h"
28 #include "w1_log.h"
29 #include "w1_netlink.h"
30 #include "w1_int.h"
31
32 static u32 w1_ids = 1;
33
34 static int w1_enable_pullup = 1;
35 module_param_named(enable_pullup, w1_enable_pullup, int, 0);
36
37 static struct w1_master * w1_alloc_dev(u32 id, int slave_count, int slave_ttl,
38                                        struct device_driver *driver,
39                                        struct device *device)
40 {
41         struct w1_master *dev;
42         int err;
43
44         /*
45          * We are in process context(kernel thread), so can sleep.
46          */
47         dev = kzalloc(sizeof(struct w1_master) + sizeof(struct w1_bus_master), GFP_KERNEL);
48         if (!dev) {
49                 printk(KERN_ERR
50                         "Failed to allocate %zd bytes for new w1 device.\n",
51                         sizeof(struct w1_master));
52                 return NULL;
53         }
54
55
56         dev->bus_master = (struct w1_bus_master *)(dev + 1);
57
58         dev->owner              = THIS_MODULE;
59         dev->max_slave_count    = slave_count;
60         dev->slave_count        = 0;
61         dev->attempts           = 0;
62         dev->initialized        = 0;
63         dev->id                 = id;
64         dev->slave_ttl          = slave_ttl;
65         dev->enable_pullup      = w1_enable_pullup;
66         dev->search_count       = -1; /* continual scan */
67
68         /* 1 for w1_process to decrement
69          * 1 for __w1_remove_master_device to decrement
70          */
71         atomic_set(&dev->refcnt, 2);
72
73         INIT_LIST_HEAD(&dev->slist);
74         mutex_init(&dev->mutex);
75
76         memcpy(&dev->dev, device, sizeof(struct device));
77         snprintf(dev->dev.bus_id, sizeof(dev->dev.bus_id),
78                   "w1_bus_master%u", dev->id);
79         snprintf(dev->name, sizeof(dev->name), "w1_bus_master%u", dev->id);
80
81         dev->driver = driver;
82
83         dev->seq = 1;
84
85         err = device_register(&dev->dev);
86         if (err) {
87                 printk(KERN_ERR "Failed to register master device. err=%d\n", err);
88                 memset(dev, 0, sizeof(struct w1_master));
89                 kfree(dev);
90                 dev = NULL;
91         }
92
93         return dev;
94 }
95
96 static void w1_free_dev(struct w1_master *dev)
97 {
98         device_unregister(&dev->dev);
99 }
100
101 int w1_add_master_device(struct w1_bus_master *master)
102 {
103         struct w1_master *dev;
104         int retval = 0;
105         struct w1_netlink_msg msg;
106
107         /* validate minimum functionality */
108         if (!(master->touch_bit && master->reset_bus) &&
109             !(master->write_bit && master->read_bit) &&
110             !(master->write_byte && master->read_byte && master->reset_bus)) {
111                 printk(KERN_ERR "w1_add_master_device: invalid function set\n");
112                 return(-EINVAL);
113         }
114         /* While it would be electrically possible to make a device that
115          * generated a strong pullup in bit bang mode, only hardare that
116          * controls 1-wire time frames are even expected to support a strong
117          * pullup.  w1_io.c would need to support calling set_pullup before
118          * the last write_bit operation of a w1_write_8 which it currently
119          * doesn't.
120          */
121         if (!master->write_byte && !master->touch_bit && master->set_pullup) {
122                 printk(KERN_ERR "w1_add_master_device: set_pullup requires "
123                         "write_byte or touch_bit, disabling\n");
124                 master->set_pullup = NULL;
125         }
126
127         dev = w1_alloc_dev(w1_ids++, w1_max_slave_count, w1_max_slave_ttl, &w1_master_driver, &w1_master_device);
128         if (!dev)
129                 return -ENOMEM;
130
131         retval =  w1_create_master_attributes(dev);
132         if (retval)
133                 goto err_out_free_dev;
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                 goto err_out_rm_attr;
146         }
147
148         mutex_lock(&w1_mlock);
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         kthread_stop(dev->thread);
162 #endif
163 err_out_rm_attr:
164         w1_destroy_master_attributes(dev);
165 err_out_free_dev:
166         w1_free_dev(dev);
167
168         return retval;
169 }
170
171 void __w1_remove_master_device(struct w1_master *dev)
172 {
173         struct w1_netlink_msg msg;
174         struct w1_slave *sl, *sln;
175
176         kthread_stop(dev->thread);
177
178         mutex_lock(&w1_mlock);
179         list_del(&dev->w1_master_entry);
180         mutex_unlock(&w1_mlock);
181
182         mutex_lock(&dev->mutex);
183         list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry)
184                 w1_slave_detach(sl);
185         w1_destroy_master_attributes(dev);
186         mutex_unlock(&dev->mutex);
187         atomic_dec(&dev->refcnt);
188
189         while (atomic_read(&dev->refcnt)) {
190                 dev_info(&dev->dev, "Waiting for %s to become free: refcnt=%d.\n",
191                                 dev->name, atomic_read(&dev->refcnt));
192
193                 if (msleep_interruptible(1000))
194                         flush_signals(current);
195         }
196
197         memset(&msg, 0, sizeof(msg));
198         msg.id.mst.id = dev->id;
199         msg.type = W1_MASTER_REMOVE;
200         w1_netlink_send(dev, &msg);
201
202         w1_free_dev(dev);
203 }
204
205 void w1_remove_master_device(struct w1_bus_master *bm)
206 {
207         struct w1_master *dev, *found = NULL;
208
209         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
210                 if (!dev->initialized)
211                         continue;
212
213                 if (dev->bus_master->data == bm->data) {
214                         found = dev;
215                         break;
216                 }
217         }
218
219         if (!found) {
220                 printk(KERN_ERR "Device doesn't exist.\n");
221                 return;
222         }
223
224         __w1_remove_master_device(found);
225 }
226
227 EXPORT_SYMBOL(w1_add_master_device);
228 EXPORT_SYMBOL(w1_remove_master_device);