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         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
 101 static void w1_free_dev(struct w1_master *dev)
 102 {
 103         device_unregister(&dev->dev);
 104 }
 105
 106 int 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. */
 186 err_out_kill_thread:
 187         kthread_stop(dev->thread);
 188 #endif
 189 err_out_rm_attr:
 190         w1_destroy_master_attributes(dev);
 191 err_out_free_dev:
 192         w1_free_dev(dev);
 193
 194         return retval;
 195 }
 196
 197 void __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
 231 void 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
 253 EXPORT_SYMBOL(w1_add_master_device);
 254 EXPORT_SYMBOL(w1_remove_master_device);