1/*
2 * Copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 */
14
15#include <linux/kernel.h>
16#include <linux/list.h>
17#include <linux/delay.h>
18#include <linux/kthread.h>
19#include <linux/slab.h>
20#include <linux/sched/signal.h>
21#include <linux/export.h>
22#include <linux/moduleparam.h>
23
24#include "w1_internal.h"
25#include "w1_netlink.h"
26
27static int w1_search_count = -1; /* Default is continual scan */
28module_param_named(search_count, w1_search_count, int, 0);
29
30static int w1_enable_pullup = 1;
31module_param_named(enable_pullup, w1_enable_pullup, int, 0);
32
33static struct w1_master *w1_alloc_dev(u32 id, int slave_count, int slave_ttl,
34 struct device_driver *driver,
35 struct device *device)
36{
37 struct w1_master *dev;
38 int err;
39
40 /*
41 * We are in process context(kernel thread), so can sleep.
42 */
43 dev = kzalloc(sizeof(struct w1_master) + sizeof(struct w1_bus_master), GFP_KERNEL);
44 if (!dev) {
45 pr_err("Failed to allocate %zd bytes for new w1 device.\n",
46 sizeof(struct w1_master));
47 return NULL;
48 }
49
50
51 dev->bus_master = (struct w1_bus_master *)(dev + 1);
52
53 dev->owner = THIS_MODULE;
54 dev->max_slave_count = slave_count;
55 dev->slave_count = 0;
56 dev->attempts = 0;
57 dev->initialized = 0;
58 dev->id = id;
59 dev->slave_ttl = slave_ttl;
60 dev->search_count = w1_search_count;
61 dev->enable_pullup = w1_enable_pullup;
62
63 /* 1 for w1_process to decrement
64 * 1 for __w1_remove_master_device to decrement
65 */
66 atomic_set(&dev->refcnt, 2);
67
68 INIT_LIST_HEAD(&dev->slist);
69 INIT_LIST_HEAD(&dev->async_list);
70 mutex_init(&dev->mutex);
71 mutex_init(&dev->bus_mutex);
72 mutex_init(&dev->list_mutex);
73
74 memcpy(&dev->dev, device, sizeof(struct device));
75 dev_set_name(&dev->dev, "w1_bus_master%u", dev->id);
76 snprintf(dev->name, sizeof(dev->name), "w1_bus_master%u", dev->id);
77 dev->dev.init_name = dev->name;
78
79 dev->driver = driver;
80
81 dev->seq = 1;
82
83 err = device_register(&dev->dev);
84 if (err) {
85 pr_err("Failed to register master device. err=%d\n", err);
86 put_device(&dev->dev);
87 dev = NULL;
88 }
89
90 return dev;
91}
92
93static void w1_free_dev(struct w1_master *dev)
94{
95 device_unregister(&dev->dev);
96}
97
98/**
99 * w1_add_master_device() - registers a new master device
100 * @master: master bus device to register
101 */
102int 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 pr_err("w1_add_master_device: invalid function set\n");
114 return(-EINVAL);
115 }
116
117 /* Lock until the device is added (or not) to w1_masters. */
118 mutex_lock(&w1_mlock);
119 /* Search for the first available id (starting at 1). */
120 id = 0;
121 do {
122 ++id;
123 found = 0;
124 list_for_each_entry(entry, &w1_masters, w1_master_entry) {
125 if (entry->id == id) {
126 found = 1;
127 break;
128 }
129 }
130 } while (found);
131
132 dev = w1_alloc_dev(id, w1_max_slave_count, w1_max_slave_ttl,
133 &w1_master_driver, &w1_master_device);
134 if (!dev) {
135 mutex_unlock(&w1_mlock);
136 return -ENOMEM;
137 }
138
139 retval = w1_create_master_attributes(dev);
140 if (retval) {
141 mutex_unlock(&w1_mlock);
142 goto err_out_free_dev;
143 }
144
145 memcpy(dev->bus_master, master, sizeof(struct w1_bus_master));
146
147 dev->initialized = 1;
148
149 dev->thread = kthread_run(&w1_process, dev, "%s", dev->name);
150 if (IS_ERR(dev->thread)) {
151 retval = PTR_ERR(dev->thread);
152 dev_err(&dev->dev,
153 "Failed to create new kernel thread. err=%d\n",
154 retval);
155 mutex_unlock(&w1_mlock);
156 goto err_out_rm_attr;
157 }
158
159 list_add(&dev->w1_master_entry, &w1_masters);
160 mutex_unlock(&w1_mlock);
161
162 memset(&msg, 0, sizeof(msg));
163 msg.id.mst.id = dev->id;
164 msg.type = W1_MASTER_ADD;
165 w1_netlink_send(dev, &msg);
166
167 return 0;
168
169#if 0 /* Thread cleanup code, not required currently. */
170err_out_kill_thread:
171 set_bit(W1_ABORT_SEARCH, &dev->flags);
172 kthread_stop(dev->thread);
173#endif
174err_out_rm_attr:
175 w1_destroy_master_attributes(dev);
176err_out_free_dev:
177 w1_free_dev(dev);
178
179 return retval;
180}
181EXPORT_SYMBOL(w1_add_master_device);
182
183void __w1_remove_master_device(struct w1_master *dev)
184{
185 struct w1_netlink_msg msg;
186 struct w1_slave *sl, *sln;
187
188 mutex_lock(&w1_mlock);
189 list_del(&dev->w1_master_entry);
190 mutex_unlock(&w1_mlock);
191
192 set_bit(W1_ABORT_SEARCH, &dev->flags);
193 kthread_stop(dev->thread);
194
195 mutex_lock(&dev->mutex);
196 mutex_lock(&dev->list_mutex);
197 list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
198 mutex_unlock(&dev->list_mutex);
199 w1_slave_detach(sl);
200 mutex_lock(&dev->list_mutex);
201 }
202 w1_destroy_master_attributes(dev);
203 mutex_unlock(&dev->list_mutex);
204 mutex_unlock(&dev->mutex);
205 atomic_dec(&dev->refcnt);
206
207 while (atomic_read(&dev->refcnt)) {
208 dev_info(&dev->dev, "Waiting for %s to become free: refcnt=%d.\n",
209 dev->name, atomic_read(&dev->refcnt));
210
211 if (msleep_interruptible(1000))
212 flush_signals(current);
213 mutex_lock(&dev->list_mutex);
214 w1_process_callbacks(dev);
215 mutex_unlock(&dev->list_mutex);
216 }
217 mutex_lock(&dev->list_mutex);
218 w1_process_callbacks(dev);
219 mutex_unlock(&dev->list_mutex);
220
221 memset(&msg, 0, sizeof(msg));
222 msg.id.mst.id = dev->id;
223 msg.type = W1_MASTER_REMOVE;
224 w1_netlink_send(dev, &msg);
225
226 w1_free_dev(dev);
227}
228
229/**
230 * w1_remove_master_device() - unregister a master device
231 * @bm: master bus device to remove
232 */
233void w1_remove_master_device(struct w1_bus_master *bm)
234{
235 struct w1_master *dev, *found = NULL;
236
237 list_for_each_entry(dev, &w1_masters, w1_master_entry) {
238 if (!dev->initialized)
239 continue;
240
241 if (dev->bus_master->data == bm->data) {
242 found = dev;
243 break;
244 }
245 }
246
247 if (!found) {
248 pr_err("Device doesn't exist.\n");
249 return;
250 }
251
252 __w1_remove_master_device(found);
253}
254EXPORT_SYMBOL(w1_remove_master_device);
255