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		pr_err("Failed to allocate %zd bytes for new w1 device.\n",
54			sizeof(struct w1_master));
55		return NULL;
56	}
57
58
59	dev->bus_master = (struct w1_bus_master *)(dev + 1);
60
61	dev->owner		= THIS_MODULE;
62	dev->max_slave_count	= slave_count;
63	dev->slave_count	= 0;
64	dev->attempts		= 0;
65	dev->initialized	= 0;
66	dev->id			= id;
67	dev->slave_ttl		= slave_ttl;
68	dev->search_count	= w1_search_count;
69	dev->enable_pullup	= w1_enable_pullup;
70
71	/* 1 for w1_process to decrement
72	 * 1 for __w1_remove_master_device to decrement
73	 */
74	atomic_set(&dev->refcnt, 2);
75
76	INIT_LIST_HEAD(&dev->slist);
77	INIT_LIST_HEAD(&dev->async_list);
78	mutex_init(&dev->mutex);
79	mutex_init(&dev->bus_mutex);
80	mutex_init(&dev->list_mutex);
81
82	memcpy(&dev->dev, device, sizeof(struct device));
83	dev_set_name(&dev->dev, "w1_bus_master%u", dev->id);
84	snprintf(dev->name, sizeof(dev->name), "w1_bus_master%u", dev->id);
85	dev->dev.init_name = dev->name;
86
87	dev->driver = driver;
88
89	dev->seq = 1;
90
91	err = device_register(&dev->dev);
92	if (err) {
93		pr_err("Failed to register master device. err=%d\n", err);
94		put_device(&dev->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
106/**
107 * w1_add_master_device() - registers a new master device
108 * @master:	master bus device to register
109 */
110int w1_add_master_device(struct w1_bus_master *master)
111{
112	struct w1_master *dev, *entry;
113	int retval = 0;
114	struct w1_netlink_msg msg;
115	int id, found;
116
117	/* validate minimum functionality */
118	if (!(master->touch_bit && master->reset_bus) &&
119	    !(master->write_bit && master->read_bit) &&
120	    !(master->write_byte && master->read_byte && master->reset_bus)) {
121		pr_err("w1_add_master_device: invalid function set\n");
122		return(-EINVAL);
123	}
124
125	/* Lock until the device is added (or not) to w1_masters. */
126	mutex_lock(&w1_mlock);
127	/* Search for the first available id (starting at 1). */
128	id = 0;
129	do {
130		++id;
131		found = 0;
132		list_for_each_entry(entry, &w1_masters, w1_master_entry) {
133			if (entry->id == id) {
134				found = 1;
135				break;
136			}
137		}
138	} while (found);
139
140	dev = w1_alloc_dev(id, w1_max_slave_count, w1_max_slave_ttl,
141		&w1_master_driver, &w1_master_device);
142	if (!dev) {
143		mutex_unlock(&w1_mlock);
144		return -ENOMEM;
145	}
146
147	retval =  w1_create_master_attributes(dev);
148	if (retval) {
149		mutex_unlock(&w1_mlock);
150		goto err_out_free_dev;
151	}
152
153	memcpy(dev->bus_master, master, sizeof(struct w1_bus_master));
154
155	dev->initialized = 1;
156
157	dev->thread = kthread_run(&w1_process, dev, "%s", dev->name);
158	if (IS_ERR(dev->thread)) {
159		retval = PTR_ERR(dev->thread);
160		dev_err(&dev->dev,
161			 "Failed to create new kernel thread. err=%d\n",
162			 retval);
163		mutex_unlock(&w1_mlock);
164		goto err_out_rm_attr;
165	}
166
167	list_add(&dev->w1_master_entry, &w1_masters);
168	mutex_unlock(&w1_mlock);
169
170	memset(&msg, 0, sizeof(msg));
171	msg.id.mst.id = dev->id;
172	msg.type = W1_MASTER_ADD;
173	w1_netlink_send(dev, &msg);
174
175	return 0;
176
177#if 0 /* Thread cleanup code, not required currently. */
178err_out_kill_thread:
179	set_bit(W1_ABORT_SEARCH, &dev->flags);
180	kthread_stop(dev->thread);
181#endif
182err_out_rm_attr:
183	w1_destroy_master_attributes(dev);
184err_out_free_dev:
185	w1_free_dev(dev);
186
187	return retval;
188}
189
190void __w1_remove_master_device(struct w1_master *dev)
191{
192	struct w1_netlink_msg msg;
193	struct w1_slave *sl, *sln;
194
195	mutex_lock(&w1_mlock);
196	list_del(&dev->w1_master_entry);
197	mutex_unlock(&w1_mlock);
198
199	set_bit(W1_ABORT_SEARCH, &dev->flags);
200	kthread_stop(dev->thread);
201
202	mutex_lock(&dev->mutex);
203	mutex_lock(&dev->list_mutex);
204	list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
205		mutex_unlock(&dev->list_mutex);
206		w1_slave_detach(sl);
207		mutex_lock(&dev->list_mutex);
208	}
209	w1_destroy_master_attributes(dev);
210	mutex_unlock(&dev->list_mutex);
211	mutex_unlock(&dev->mutex);
212	atomic_dec(&dev->refcnt);
213
214	while (atomic_read(&dev->refcnt)) {
215		dev_info(&dev->dev, "Waiting for %s to become free: refcnt=%d.\n",
216				dev->name, atomic_read(&dev->refcnt));
217
218		if (msleep_interruptible(1000))
219			flush_signals(current);
220		mutex_lock(&dev->list_mutex);
221		w1_process_callbacks(dev);
222		mutex_unlock(&dev->list_mutex);
223	}
224	mutex_lock(&dev->list_mutex);
225	w1_process_callbacks(dev);
226	mutex_unlock(&dev->list_mutex);
227
228	memset(&msg, 0, sizeof(msg));
229	msg.id.mst.id = dev->id;
230	msg.type = W1_MASTER_REMOVE;
231	w1_netlink_send(dev, &msg);
232
233	w1_free_dev(dev);
234}
235
236/**
237 * w1_remove_master_device() - unregister a master device
238 * @bm:	master bus device to remove
239 */
240void w1_remove_master_device(struct w1_bus_master *bm)
241{
242	struct w1_master *dev, *found = NULL;
243
244	list_for_each_entry(dev, &w1_masters, w1_master_entry) {
245		if (!dev->initialized)
246			continue;
247
248		if (dev->bus_master->data == bm->data) {
249			found = dev;
250			break;
251		}
252	}
253
254	if (!found) {
255		pr_err("Device doesn't exist.\n");
256		return;
257	}
258
259	__w1_remove_master_device(found);
260}
261
262EXPORT_SYMBOL(w1_add_master_device);
263EXPORT_SYMBOL(w1_remove_master_device);
264