Merge git://bedivere.hansenpartnership.com/git/scsi-rc-fixes-2.6
[linux-2.6.git] / drivers / w1 / w1_int.c
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
28 #include "w1.h"
29 #include "w1_log.h"
30 #include "w1_netlink.h"
31 #include "w1_int.h"
32
33 static int w1_search_count = -1; /* Default is continual scan */
34 module_param_named(search_count, w1_search_count, int, 0);
35
36 static int w1_enable_pullup = 1;
37 module_param_named(enable_pullup, w1_enable_pullup, int, 0);
38
39 static struct w1_master * w1_alloc_dev(u32 id, int slave_count, int slave_ttl,
40                                        struct device_driver *driver,
41                                        struct device *device)
42 {
43         struct w1_master *dev;
44         int err;
45
46         /*
47          * We are in process context(kernel thread), so can sleep.
48          */
49         dev = kzalloc(sizeof(struct w1_master) + sizeof(struct w1_bus_master), GFP_KERNEL);
50         if (!dev) {
51                 printk(KERN_ERR
52                         "Failed to allocate %zd bytes for new w1 device.\n",
53                         sizeof(struct w1_master));
54                 return NULL;
55         }
56
57
58         dev->bus_master = (struct w1_bus_master *)(dev + 1);
59
60         dev->owner              = THIS_MODULE;
61         dev->max_slave_count    = slave_count;
62         dev->slave_count        = 0;
63         dev->attempts           = 0;
64         dev->initialized        = 0;
65         dev->id                 = id;
66         dev->slave_ttl          = slave_ttl;
67         dev->search_count       = w1_search_count;
68         dev->enable_pullup      = w1_enable_pullup;
69
70         /* 1 for w1_process to decrement
71          * 1 for __w1_remove_master_device to decrement
72          */
73         atomic_set(&dev->refcnt, 2);
74
75         INIT_LIST_HEAD(&dev->slist);
76         mutex_init(&dev->mutex);
77
78         memcpy(&dev->dev, device, sizeof(struct device));
79         dev_set_name(&dev->dev, "w1_bus_master%u", dev->id);
80         snprintf(dev->name, sizeof(dev->name), "w1_bus_master%u", dev->id);
81
82         dev->driver = driver;
83
84         dev->seq = 1;
85
86         err = device_register(&dev->dev);
87         if (err) {
88                 printk(KERN_ERR "Failed to register master device. err=%d\n", err);
89                 memset(dev, 0, sizeof(struct w1_master));
90                 kfree(dev);
91                 dev = NULL;
92         }
93
94         return dev;
95 }
96
97 static void w1_free_dev(struct w1_master *dev)
98 {
99         device_unregister(&dev->dev);
100 }
101
102 int w1_add_master_device(struct w1_bus_master *master)
103 {
104         struct w1_master *dev, *entry;
105         int retval = 0;
106         struct w1_netlink_msg msg;
107         int id, found;
108
109         /* validate minimum functionality */
110         if (!(master->touch_bit && master->reset_bus) &&
111             !(master->write_bit && master->read_bit) &&
112             !(master->write_byte && master->read_byte && master->reset_bus)) {
113                 printk(KERN_ERR "w1_add_master_device: invalid function set\n");
114                 return(-EINVAL);
115         }
116         /* While it would be electrically possible to make a device that
117          * generated a strong pullup in bit bang mode, only hardare that
118          * controls 1-wire time frames are even expected to support a strong
119          * pullup.  w1_io.c would need to support calling set_pullup before
120          * the last write_bit operation of a w1_write_8 which it currently
121          * doesn't.
122          */
123         if (!master->write_byte && !master->touch_bit && master->set_pullup) {
124                 printk(KERN_ERR "w1_add_master_device: set_pullup requires "
125                         "write_byte or touch_bit, disabling\n");
126                 master->set_pullup = NULL;
127         }
128
129         /* Lock until the device is added (or not) to w1_masters. */
130         mutex_lock(&w1_mlock);
131         /* Search for the first available id (starting at 1). */
132         id = 0;
133         do {
134                 ++id;
135                 found = 0;
136                 list_for_each_entry(entry, &w1_masters, w1_master_entry) {
137                         if (entry->id == id) {
138                                 found = 1;
139                                 break;
140                         }
141                 }
142         } while (found);
143
144         dev = w1_alloc_dev(id, w1_max_slave_count, w1_max_slave_ttl,
145                 &w1_master_driver, &w1_master_device);
146         if (!dev) {
147                 mutex_unlock(&w1_mlock);
148                 return -ENOMEM;
149         }
150
151         retval =  w1_create_master_attributes(dev);
152         if (retval) {
153                 mutex_unlock(&w1_mlock);
154                 goto err_out_free_dev;
155         }
156
157         memcpy(dev->bus_master, master, sizeof(struct w1_bus_master));
158
159         dev->initialized = 1;
160
161         dev->thread = kthread_run(&w1_process, dev, "%s", dev->name);
162         if (IS_ERR(dev->thread)) {
163                 retval = PTR_ERR(dev->thread);
164                 dev_err(&dev->dev,
165                          "Failed to create new kernel thread. err=%d\n",
166                          retval);
167                 mutex_unlock(&w1_mlock);
168                 goto err_out_rm_attr;
169         }
170
171         list_add(&dev->w1_master_entry, &w1_masters);
172         mutex_unlock(&w1_mlock);
173
174         memset(&msg, 0, sizeof(msg));
175         msg.id.mst.id = dev->id;
176         msg.type = W1_MASTER_ADD;
177         w1_netlink_send(dev, &msg);
178
179         return 0;
180
181 #if 0 /* Thread cleanup code, not required currently. */
182 err_out_kill_thread:
183         kthread_stop(dev->thread);
184 #endif
185 err_out_rm_attr:
186         w1_destroy_master_attributes(dev);
187 err_out_free_dev:
188         w1_free_dev(dev);
189
190         return retval;
191 }
192
193 void __w1_remove_master_device(struct w1_master *dev)
194 {
195         struct w1_netlink_msg msg;
196         struct w1_slave *sl, *sln;
197
198         kthread_stop(dev->thread);
199
200         mutex_lock(&w1_mlock);
201         list_del(&dev->w1_master_entry);
202         mutex_unlock(&w1_mlock);
203
204         mutex_lock(&dev->mutex);
205         list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry)
206                 w1_slave_detach(sl);
207         w1_destroy_master_attributes(dev);
208         mutex_unlock(&dev->mutex);
209         atomic_dec(&dev->refcnt);
210
211         while (atomic_read(&dev->refcnt)) {
212                 dev_info(&dev->dev, "Waiting for %s to become free: refcnt=%d.\n",
213                                 dev->name, atomic_read(&dev->refcnt));
214
215                 if (msleep_interruptible(1000))
216                         flush_signals(current);
217         }
218
219         memset(&msg, 0, sizeof(msg));
220         msg.id.mst.id = dev->id;
221         msg.type = W1_MASTER_REMOVE;
222         w1_netlink_send(dev, &msg);
223
224         w1_free_dev(dev);
225 }
226
227 void w1_remove_master_device(struct w1_bus_master *bm)
228 {
229         struct w1_master *dev, *found = NULL;
230
231         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
232                 if (!dev->initialized)
233                         continue;
234
235                 if (dev->bus_master->data == bm->data) {
236                         found = dev;
237                         break;
238                 }
239         }
240
241         if (!found) {
242                 printk(KERN_ERR "Device doesn't exist.\n");
243                 return;
244         }
245
246         __w1_remove_master_device(found);
247 }
248
249 EXPORT_SYMBOL(w1_add_master_device);
250 EXPORT_SYMBOL(w1_remove_master_device);