drivers/w1/w1_int.c

   1 /*
   2  *      w1_int.c
   3  *
   4  * Copyright (c) 2004 Evgeniy Polyakov <johnpol@2ka.mipt.ru>
   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
  27 #include "w1.h"
  28 #include "w1_log.h"
  29 #include "w1_netlink.h"
  30 #include "w1_int.h"
  31
  32 static int w1_search_count = -1; /* Default is continual scan */
  33 module_param_named(search_count, w1_search_count, int, 0);
  34
  35 static int w1_enable_pullup = 1;
  36 module_param_named(enable_pullup, w1_enable_pullup, int, 0);
  37
  38 static struct w1_master * w1_alloc_dev(u32 id, int slave_count, int slave_ttl,
  39                                        struct device_driver *driver,
  40                                        struct device *device)
  41 {
  42         struct w1_master *dev;
  43         int err;
  44
  45         /*
  46          * We are in process context(kernel thread), so can sleep.
  47          */
  48         dev = kzalloc(sizeof(struct w1_master) + sizeof(struct w1_bus_master), GFP_KERNEL);
  49         if (!dev) {
  50                 printk(KERN_ERR
  51                         "Failed to allocate %zd bytes for new w1 device.\n",
  52                         sizeof(struct w1_master));
  53                 return NULL;
  54         }
  55
  56
  57         dev->bus_master = (struct w1_bus_master *)(dev + 1);
  58
  59         dev->owner              = THIS_MODULE;
  60         dev->max_slave_count    = slave_count;
  61         dev->slave_count        = 0;
  62         dev->attempts           = 0;
  63         dev->initialized        = 0;
  64         dev->id                 = id;
  65         dev->slave_ttl          = slave_ttl;
  66         dev->search_count       = w1_search_count;
  67         dev->enable_pullup      = w1_enable_pullup;
  68
  69         /* 1 for w1_process to decrement
  70          * 1 for __w1_remove_master_device to decrement
  71          */
  72         atomic_set(&dev->refcnt, 2);
  73
  74         INIT_LIST_HEAD(&dev->slist);
  75         mutex_init(&dev->mutex);
  76
  77         memcpy(&dev->dev, device, sizeof(struct device));
  78         dev_set_name(&dev->dev, "w1_bus_master%u", dev->id);
  79         snprintf(dev->name, sizeof(dev->name), "w1_bus_master%u", dev->id);
  80
  81         dev->driver = driver;
  82
  83         dev->seq = 1;
  84
  85         err = device_register(&dev->dev);
  86         if (err) {
  87                 printk(KERN_ERR "Failed to register master device. err=%d\n", err);
  88                 memset(dev, 0, sizeof(struct w1_master));
  89                 kfree(dev);
  90                 dev = NULL;
  91         }
  92
  93         return dev;
  94 }
  95
  96 static void w1_free_dev(struct w1_master *dev)
  97 {
  98         device_unregister(&dev->dev);
  99 }
 100
 101 int w1_add_master_device(struct w1_bus_master *master)
 102 {
 103         struct w1_master *dev, *entry;
 104         int retval = 0;
 105         struct w1_netlink_msg msg;
 106         int id, found;
 107
 108         /* validate minimum functionality */
 109         if (!(master->touch_bit && master->reset_bus) &&
 110             !(master->write_bit && master->read_bit) &&
 111             !(master->write_byte && master->read_byte && master->reset_bus)) {
 112                 printk(KERN_ERR "w1_add_master_device: invalid function set\n");
 113                 return(-EINVAL);
 114         }
 115         /* While it would be electrically possible to make a device that
 116          * generated a strong pullup in bit bang mode, only hardare that
 117          * controls 1-wire time frames are even expected to support a strong
 118          * pullup.  w1_io.c would need to support calling set_pullup before
 119          * the last write_bit operation of a w1_write_8 which it currently
 120          * doesn't.
 121          */
 122         if (!master->write_byte && !master->touch_bit && master->set_pullup) {
 123                 printk(KERN_ERR "w1_add_master_device: set_pullup requires "
 124                         "write_byte or touch_bit, disabling\n");
 125                 master->set_pullup = NULL;
 126         }
 127
 128         /* Lock until the device is added (or not) to w1_masters. */
 129         mutex_lock(&w1_mlock);
 130         /* Search for the first available id (starting at 1). */
 131         id = 0;
 132         do {
 133                 ++id;
 134                 found = 0;
 135                 list_for_each_entry(entry, &w1_masters, w1_master_entry) {
 136                         if (entry->id == id) {
 137                                 found = 1;
 138                                 break;
 139                         }
 140                 }
 141         } while (found);
 142
 143         dev = w1_alloc_dev(id, w1_max_slave_count, w1_max_slave_ttl,
 144                 &w1_master_driver, &w1_master_device);
 145         if (!dev) {
 146                 mutex_unlock(&w1_mlock);
 147                 return -ENOMEM;
 148         }
 149
 150         retval =  w1_create_master_attributes(dev);
 151         if (retval) {
 152                 mutex_unlock(&w1_mlock);
 153                 goto err_out_free_dev;
 154         }
 155
 156         memcpy(dev->bus_master, master, sizeof(struct w1_bus_master));
 157
 158         dev->initialized = 1;
 159
 160         dev->thread = kthread_run(&w1_process, dev, "%s", dev->name);
 161         if (IS_ERR(dev->thread)) {
 162                 retval = PTR_ERR(dev->thread);
 163                 dev_err(&dev->dev,
 164                          "Failed to create new kernel thread. err=%d\n",
 165                          retval);
 166                 mutex_unlock(&w1_mlock);
 167                 goto err_out_rm_attr;
 168         }
 169
 170         list_add(&dev->w1_master_entry, &w1_masters);
 171         mutex_unlock(&w1_mlock);
 172
 173         memset(&msg, 0, sizeof(msg));
 174         msg.id.mst.id = dev->id;
 175         msg.type = W1_MASTER_ADD;
 176         w1_netlink_send(dev, &msg);
 177
 178         return 0;
 179
 180 #if 0 /* Thread cleanup code, not required currently. */
 181 err_out_kill_thread:
 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         kthread_stop(dev->thread);
 198
 199         mutex_lock(&w1_mlock);
 200         list_del(&dev->w1_master_entry);
 201         mutex_unlock(&w1_mlock);
 202
 203         mutex_lock(&dev->mutex);
 204         list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry)
 205                 w1_slave_detach(sl);
 206         w1_destroy_master_attributes(dev);
 207         mutex_unlock(&dev->mutex);
 208         atomic_dec(&dev->refcnt);
 209
 210         while (atomic_read(&dev->refcnt)) {
 211                 dev_info(&dev->dev, "Waiting for %s to become free: refcnt=%d.\n",
 212                                 dev->name, atomic_read(&dev->refcnt));
 213
 214                 if (msleep_interruptible(1000))
 215                         flush_signals(current);
 216         }
 217
 218         memset(&msg, 0, sizeof(msg));
 219         msg.id.mst.id = dev->id;
 220         msg.type = W1_MASTER_REMOVE;
 221         w1_netlink_send(dev, &msg);
 222
 223         w1_free_dev(dev);
 224 }
 225
 226 void w1_remove_master_device(struct w1_bus_master *bm)
 227 {
 228         struct w1_master *dev, *found = NULL;
 229
 230         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
 231                 if (!dev->initialized)
 232                         continue;
 233
 234                 if (dev->bus_master->data == bm->data) {
 235                         found = dev;
 236                         break;
 237                 }
 238         }
 239
 240         if (!found) {
 241                 printk(KERN_ERR "Device doesn't exist.\n");
 242                 return;
 243         }
 244
 245         __w1_remove_master_device(found);
 246 }
 247
 248 EXPORT_SYMBOL(w1_add_master_device);
 249 EXPORT_SYMBOL(w1_remove_master_device);