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
  35 static int w1_search_count = -1; /* Default is continual scan */
  36 module_param_named(search_count, w1_search_count, int, 0);
  37
  38 static int w1_enable_pullup = 1;
  39 module_param_named(enable_pullup, w1_enable_pullup, int, 0);
  40
  41 static 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         INIT_LIST_HEAD(&dev->async_list);
  79         mutex_init(&dev->mutex);
  80         mutex_init(&dev->bus_mutex);
  81         mutex_init(&dev->list_mutex);
  82
  83         memcpy(&dev->dev, device, sizeof(struct device));
  84         dev_set_name(&dev->dev, "w1_bus_master%u", dev->id);
  85         snprintf(dev->name, sizeof(dev->name), "w1_bus_master%u", dev->id);
  86         dev->dev.init_name = dev->name;
  87
  88         dev->driver = driver;
  89
  90         dev->seq = 1;
  91
  92         err = device_register(&dev->dev);
  93         if (err) {
  94                 printk(KERN_ERR "Failed to register master device. err=%d\n", err);
  95                 memset(dev, 0, sizeof(struct w1_master));
  96                 kfree(dev);
  97                 dev = NULL;
  98         }
  99
 100         return dev;
 101 }
 102
 103 static void w1_free_dev(struct w1_master *dev)
 104 {
 105         device_unregister(&dev->dev);
 106 }
 107
 108 /**
 109  * w1_add_master_device() - registers a new master device
 110  * @master:     master bus device to register
 111  */
 112 int w1_add_master_device(struct w1_bus_master *master)
 113 {
 114         struct w1_master *dev, *entry;
 115         int retval = 0;
 116         struct w1_netlink_msg msg;
 117         int id, found;
 118
 119         /* validate minimum functionality */
 120         if (!(master->touch_bit && master->reset_bus) &&
 121             !(master->write_bit && master->read_bit) &&
 122             !(master->write_byte && master->read_byte && master->reset_bus)) {
 123                 printk(KERN_ERR "w1_add_master_device: invalid function set\n");
 124                 return(-EINVAL);
 125         }
 126
 127         /* Lock until the device is added (or not) to w1_masters. */
 128         mutex_lock(&w1_mlock);
 129         /* Search for the first available id (starting at 1). */
 130         id = 0;
 131         do {
 132                 ++id;
 133                 found = 0;
 134                 list_for_each_entry(entry, &w1_masters, w1_master_entry) {
 135                         if (entry->id == id) {
 136                                 found = 1;
 137                                 break;
 138                         }
 139                 }
 140         } while (found);
 141
 142         dev = w1_alloc_dev(id, w1_max_slave_count, w1_max_slave_ttl,
 143                 &w1_master_driver, &w1_master_device);
 144         if (!dev) {
 145                 mutex_unlock(&w1_mlock);
 146                 return -ENOMEM;
 147         }
 148
 149         retval =  w1_create_master_attributes(dev);
 150         if (retval) {
 151                 mutex_unlock(&w1_mlock);
 152                 goto err_out_free_dev;
 153         }
 154
 155         memcpy(dev->bus_master, master, sizeof(struct w1_bus_master));
 156
 157         dev->initialized = 1;
 158
 159         dev->thread = kthread_run(&w1_process, dev, "%s", dev->name);
 160         if (IS_ERR(dev->thread)) {
 161                 retval = PTR_ERR(dev->thread);
 162                 dev_err(&dev->dev,
 163                          "Failed to create new kernel thread. err=%d\n",
 164                          retval);
 165                 mutex_unlock(&w1_mlock);
 166                 goto err_out_rm_attr;
 167         }
 168
 169         list_add(&dev->w1_master_entry, &w1_masters);
 170         mutex_unlock(&w1_mlock);
 171
 172         memset(&msg, 0, sizeof(msg));
 173         msg.id.mst.id = dev->id;
 174         msg.type = W1_MASTER_ADD;
 175         w1_netlink_send(dev, &msg);
 176
 177         return 0;
 178
 179 #if 0 /* Thread cleanup code, not required currently. */
 180 err_out_kill_thread:
 181         set_bit(W1_ABORT_SEARCH, &dev->flags);
 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         mutex_lock(&w1_mlock);
 198         list_del(&dev->w1_master_entry);
 199         mutex_unlock(&w1_mlock);
 200
 201         set_bit(W1_ABORT_SEARCH, &dev->flags);
 202         kthread_stop(dev->thread);
 203
 204         mutex_lock(&dev->mutex);
 205         mutex_lock(&dev->list_mutex);
 206         list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
 207                 mutex_unlock(&dev->list_mutex);
 208                 w1_slave_detach(sl);
 209                 mutex_lock(&dev->list_mutex);
 210         }
 211         w1_destroy_master_attributes(dev);
 212         mutex_unlock(&dev->list_mutex);
 213         mutex_unlock(&dev->mutex);
 214         atomic_dec(&dev->refcnt);
 215
 216         while (atomic_read(&dev->refcnt)) {
 217                 dev_info(&dev->dev, "Waiting for %s to become free: refcnt=%d.\n",
 218                                 dev->name, atomic_read(&dev->refcnt));
 219
 220                 if (msleep_interruptible(1000))
 221                         flush_signals(current);
 222                 w1_process_callbacks(dev);
 223         }
 224         w1_process_callbacks(dev);
 225
 226         memset(&msg, 0, sizeof(msg));
 227         msg.id.mst.id = dev->id;
 228         msg.type = W1_MASTER_REMOVE;
 229         w1_netlink_send(dev, &msg);
 230
 231         w1_free_dev(dev);
 232 }
 233
 234 /**
 235  * w1_remove_master_device() - unregister a master device
 236  * @bm: master bus device to remove
 237  */
 238 void w1_remove_master_device(struct w1_bus_master *bm)
 239 {
 240         struct w1_master *dev, *found = NULL;
 241
 242         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
 243                 if (!dev->initialized)
 244                         continue;
 245
 246                 if (dev->bus_master->data == bm->data) {
 247                         found = dev;
 248                         break;
 249                 }
 250         }
 251
 252         if (!found) {
 253                 printk(KERN_ERR "Device doesn't exist.\n");
 254                 return;
 255         }
 256
 257         __w1_remove_master_device(found);
 258 }
 259
 260 EXPORT_SYMBOL(w1_add_master_device);
 261 EXPORT_SYMBOL(w1_remove_master_device);