Root/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#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
35static int w1_search_count = -1; /* Default is continual scan */
36module_param_named(search_count, w1_search_count, int, 0);
37
38static int w1_enable_pullup = 1;
39module_param_named(enable_pullup, w1_enable_pullup, int, 0);
40
41static 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    mutex_init(&dev->mutex);
79    mutex_init(&dev->bus_mutex);
80
81    memcpy(&dev->dev, device, sizeof(struct device));
82    dev_set_name(&dev->dev, "w1_bus_master%u", dev->id);
83    snprintf(dev->name, sizeof(dev->name), "w1_bus_master%u", dev->id);
84    dev->dev.init_name = dev->name;
85
86    dev->driver = driver;
87
88    dev->seq = 1;
89
90    err = device_register(&dev->dev);
91    if (err) {
92        printk(KERN_ERR "Failed to register master device. err=%d\n", err);
93        memset(dev, 0, sizeof(struct w1_master));
94        kfree(dev);
95        dev = NULL;
96    }
97
98    return dev;
99}
100
101static void w1_free_dev(struct w1_master *dev)
102{
103    device_unregister(&dev->dev);
104}
105
106int w1_add_master_device(struct w1_bus_master *master)
107{
108    struct w1_master *dev, *entry;
109    int retval = 0;
110    struct w1_netlink_msg msg;
111    int id, found;
112
113        /* validate minimum functionality */
114        if (!(master->touch_bit && master->reset_bus) &&
115            !(master->write_bit && master->read_bit) &&
116        !(master->write_byte && master->read_byte && master->reset_bus)) {
117        printk(KERN_ERR "w1_add_master_device: invalid function set\n");
118        return(-EINVAL);
119        }
120    /* While it would be electrically possible to make a device that
121     * generated a strong pullup in bit bang mode, only hardware that
122     * controls 1-wire time frames are even expected to support a strong
123     * pullup. w1_io.c would need to support calling set_pullup before
124     * the last write_bit operation of a w1_write_8 which it currently
125     * doesn't.
126     */
127    if (!master->write_byte && !master->touch_bit && master->set_pullup) {
128        printk(KERN_ERR "w1_add_master_device: set_pullup requires "
129            "write_byte or touch_bit, disabling\n");
130        master->set_pullup = NULL;
131    }
132
133    /* Lock until the device is added (or not) to w1_masters. */
134    mutex_lock(&w1_mlock);
135    /* Search for the first available id (starting at 1). */
136    id = 0;
137    do {
138        ++id;
139        found = 0;
140        list_for_each_entry(entry, &w1_masters, w1_master_entry) {
141            if (entry->id == id) {
142                found = 1;
143                break;
144            }
145        }
146    } while (found);
147
148    dev = w1_alloc_dev(id, w1_max_slave_count, w1_max_slave_ttl,
149        &w1_master_driver, &w1_master_device);
150    if (!dev) {
151        mutex_unlock(&w1_mlock);
152        return -ENOMEM;
153    }
154
155    retval = w1_create_master_attributes(dev);
156    if (retval) {
157        mutex_unlock(&w1_mlock);
158        goto err_out_free_dev;
159    }
160
161    memcpy(dev->bus_master, master, sizeof(struct w1_bus_master));
162
163    dev->initialized = 1;
164
165    dev->thread = kthread_run(&w1_process, dev, "%s", dev->name);
166    if (IS_ERR(dev->thread)) {
167        retval = PTR_ERR(dev->thread);
168        dev_err(&dev->dev,
169             "Failed to create new kernel thread. err=%d\n",
170             retval);
171        mutex_unlock(&w1_mlock);
172        goto err_out_rm_attr;
173    }
174
175    list_add(&dev->w1_master_entry, &w1_masters);
176    mutex_unlock(&w1_mlock);
177
178    memset(&msg, 0, sizeof(msg));
179    msg.id.mst.id = dev->id;
180    msg.type = W1_MASTER_ADD;
181    w1_netlink_send(dev, &msg);
182
183    return 0;
184
185#if 0 /* Thread cleanup code, not required currently. */
186err_out_kill_thread:
187    kthread_stop(dev->thread);
188#endif
189err_out_rm_attr:
190    w1_destroy_master_attributes(dev);
191err_out_free_dev:
192    w1_free_dev(dev);
193
194    return retval;
195}
196
197void __w1_remove_master_device(struct w1_master *dev)
198{
199    struct w1_netlink_msg msg;
200    struct w1_slave *sl, *sln;
201
202    kthread_stop(dev->thread);
203
204    mutex_lock(&w1_mlock);
205    list_del(&dev->w1_master_entry);
206    mutex_unlock(&w1_mlock);
207
208    mutex_lock(&dev->mutex);
209    list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry)
210        w1_slave_detach(sl);
211    w1_destroy_master_attributes(dev);
212    mutex_unlock(&dev->mutex);
213    atomic_dec(&dev->refcnt);
214
215    while (atomic_read(&dev->refcnt)) {
216        dev_info(&dev->dev, "Waiting for %s to become free: refcnt=%d.\n",
217                dev->name, atomic_read(&dev->refcnt));
218
219        if (msleep_interruptible(1000))
220            flush_signals(current);
221    }
222
223    memset(&msg, 0, sizeof(msg));
224    msg.id.mst.id = dev->id;
225    msg.type = W1_MASTER_REMOVE;
226    w1_netlink_send(dev, &msg);
227
228    w1_free_dev(dev);
229}
230
231void w1_remove_master_device(struct w1_bus_master *bm)
232{
233    struct w1_master *dev, *found = NULL;
234
235    list_for_each_entry(dev, &w1_masters, w1_master_entry) {
236        if (!dev->initialized)
237            continue;
238
239        if (dev->bus_master->data == bm->data) {
240            found = dev;
241            break;
242        }
243    }
244
245    if (!found) {
246        printk(KERN_ERR "Device doesn't exist.\n");
247        return;
248    }
249
250    __w1_remove_master_device(found);
251}
252
253EXPORT_SYMBOL(w1_add_master_device);
254EXPORT_SYMBOL(w1_remove_master_device);
255

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