Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-2.6
[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 int w1_search_count = -1; /* Default is continual scan */
33 module_param_named(search_count, w1_search_count, int, 0);
34
35 static int w1_enable_pullup = 1;
36 module_param_named(enable_pullup, w1_enable_pullup, int, 0);
37
38 static struct w1_master * w1_alloc_dev(u32 id, int slave_count, int slave_ttl,
39                                        struct device_driver *driver,
40                                        struct device *device)
41 {
42         struct w1_master *dev;
43         int err;
44
45         /*
46          * We are in process context(kernel thread), so can sleep.
47          */
48         dev = kzalloc(sizeof(struct w1_master) + sizeof(struct w1_bus_master), GFP_KERNEL);
49         if (!dev) {
50                 printk(KERN_ERR
51                         "Failed to allocate %zd bytes for new w1 device.\n",
52                         sizeof(struct w1_master));
53                 return NULL;
54         }
55
56
57         dev->bus_master = (struct w1_bus_master *)(dev + 1);
58
59         dev->owner              = THIS_MODULE;
60         dev->max_slave_count    = slave_count;
61         dev->slave_count        = 0;
62         dev->attempts           = 0;
63         dev->initialized        = 0;
64         dev->id                 = id;
65         dev->slave_ttl          = slave_ttl;
66         dev->search_count       = w1_search_count;
67         dev->enable_pullup      = w1_enable_pullup;
68
69         /* 1 for w1_process to decrement
70          * 1 for __w1_remove_master_device to decrement
71          */
72         atomic_set(&dev->refcnt, 2);
73
74         INIT_LIST_HEAD(&dev->slist);
75         mutex_init(&dev->mutex);
76
77         memcpy(&dev->dev, device, sizeof(struct device));
78         dev_set_name(&dev->dev, "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, *entry;
104         int retval = 0;
105         struct w1_netlink_msg msg;
106         int id, found;
107
108         /* validate minimum functionality */
109         if (!(master->touch_bit && master->reset_bus) &&
110             !(master->write_bit && master->read_bit) &&
111             !(master->write_byte && master->read_byte && master->reset_bus)) {
112                 printk(KERN_ERR "w1_add_master_device: invalid function set\n");
113                 return(-EINVAL);
114         }
115         /* While it would be electrically possible to make a device that
116          * generated a strong pullup in bit bang mode, only hardare that
117          * controls 1-wire time frames are even expected to support a strong
118          * pullup.  w1_io.c would need to support calling set_pullup before
119          * the last write_bit operation of a w1_write_8 which it currently
120          * doesn't.
121          */
122         if (!master->write_byte && !master->touch_bit && master->set_pullup) {
123                 printk(KERN_ERR "w1_add_master_device: set_pullup requires "
124                         "write_byte or touch_bit, disabling\n");
125                 master->set_pullup = NULL;
126         }
127
128         /* Lock until the device is added (or not) to w1_masters. */
129         mutex_lock(&w1_mlock);
130         /* Search for the first available id (starting at 1). */
131         id = 0;
132         do {
133                 ++id;
134                 found = 0;
135                 list_for_each_entry(entry, &w1_masters, w1_master_entry) {
136                         if (entry->id == id) {
137                                 found = 1;
138                                 break;
139                         }
140                 }
141         } while (found);
142
143         dev = w1_alloc_dev(id, w1_max_slave_count, w1_max_slave_ttl,
144                 &w1_master_driver, &w1_master_device);
145         if (!dev) {
146                 mutex_unlock(&w1_mlock);
147                 return -ENOMEM;
148         }
149
150         retval =  w1_create_master_attributes(dev);
151         if (retval) {
152                 mutex_unlock(&w1_mlock);
153                 goto err_out_free_dev;
154         }
155
156         memcpy(dev->bus_master, master, sizeof(struct w1_bus_master));
157
158         dev->initialized = 1;
159
160         dev->thread = kthread_run(&w1_process, dev, "%s", dev->name);
161         if (IS_ERR(dev->thread)) {
162                 retval = PTR_ERR(dev->thread);
163                 dev_err(&dev->dev,
164                          "Failed to create new kernel thread. err=%d\n",
165                          retval);
166                 mutex_unlock(&w1_mlock);
167                 goto err_out_rm_attr;
168         }
169
170         list_add(&dev->w1_master_entry, &w1_masters);
171         mutex_unlock(&w1_mlock);
172
173         memset(&msg, 0, sizeof(msg));
174         msg.id.mst.id = dev->id;
175         msg.type = W1_MASTER_ADD;
176         w1_netlink_send(dev, &msg);
177
178         return 0;
179
180 #if 0 /* Thread cleanup code, not required currently. */
181 err_out_kill_thread:
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         kthread_stop(dev->thread);
198
199         mutex_lock(&w1_mlock);
200         list_del(&dev->w1_master_entry);
201         mutex_unlock(&w1_mlock);
202
203         mutex_lock(&dev->mutex);
204         list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry)
205                 w1_slave_detach(sl);
206         w1_destroy_master_attributes(dev);
207         mutex_unlock(&dev->mutex);
208         atomic_dec(&dev->refcnt);
209
210         while (atomic_read(&dev->refcnt)) {
211                 dev_info(&dev->dev, "Waiting for %s to become free: refcnt=%d.\n",
212                                 dev->name, atomic_read(&dev->refcnt));
213
214                 if (msleep_interruptible(1000))
215                         flush_signals(current);
216         }
217
218         memset(&msg, 0, sizeof(msg));
219         msg.id.mst.id = dev->id;
220         msg.type = W1_MASTER_REMOVE;
221         w1_netlink_send(dev, &msg);
222
223         w1_free_dev(dev);
224 }
225
226 void w1_remove_master_device(struct w1_bus_master *bm)
227 {
228         struct w1_master *dev, *found = NULL;
229
230         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
231                 if (!dev->initialized)
232                         continue;
233
234                 if (dev->bus_master->data == bm->data) {
235                         found = dev;
236                         break;
237                 }
238         }
239
240         if (!found) {
241                 printk(KERN_ERR "Device doesn't exist.\n");
242                 return;
243         }
244
245         __w1_remove_master_device(found);
246 }
247
248 EXPORT_SYMBOL(w1_add_master_device);
249 EXPORT_SYMBOL(w1_remove_master_device);