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                 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
 101 static 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  */
 110 int 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. */
 178 err_out_kill_thread:
 179         set_bit(W1_ABORT_SEARCH, &dev->flags);
 180         kthread_stop(dev->thread);
 181 #endif
 182 err_out_rm_attr:
 183         w1_destroy_master_attributes(dev);
 184 err_out_free_dev:
 185         w1_free_dev(dev);
 186
 187         return retval;
 188 }
 189
 190 void __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  */
 240 void 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
 262 EXPORT_SYMBOL(w1_add_master_device);
 263 EXPORT_SYMBOL(w1_remove_master_device);