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
  28 #include "w1.h"
  29 #include "w1_log.h"
  30 #include "w1_netlink.h"
  31 #include "w1_int.h"
  32
  33 static int w1_search_count = -1; /* Default is continual scan */
  34 module_param_named(search_count, w1_search_count, int, 0);
  35
  36 static int w1_enable_pullup = 1;
  37 module_param_named(enable_pullup, w1_enable_pullup, int, 0);
  38
  39 static struct w1_master * w1_alloc_dev(u32 id, int slave_count, int slave_ttl,
  40                                        struct device_driver *driver,
  41                                        struct device *device)
  42 {
  43         struct w1_master *dev;
  44         int err;
  45
  46         /*
  47          * We are in process context(kernel thread), so can sleep.
  48          */
  49         dev = kzalloc(sizeof(struct w1_master) + sizeof(struct w1_bus_master), GFP_KERNEL);
  50         if (!dev) {
  51                 printk(KERN_ERR
  52                         "Failed to allocate %zd bytes for new w1 device.\n",
  53                         sizeof(struct w1_master));
  54                 return NULL;
  55         }
  56
  57
  58         dev->bus_master = (struct w1_bus_master *)(dev + 1);
  59
  60         dev->owner              = THIS_MODULE;
  61         dev->max_slave_count    = slave_count;
  62         dev->slave_count        = 0;
  63         dev->attempts           = 0;
  64         dev->initialized        = 0;
  65         dev->id                 = id;
  66         dev->slave_ttl          = slave_ttl;
  67         dev->search_count       = w1_search_count;
  68         dev->enable_pullup      = w1_enable_pullup;
  69
  70         /* 1 for w1_process to decrement
  71          * 1 for __w1_remove_master_device to decrement
  72          */
  73         atomic_set(&dev->refcnt, 2);
  74
  75         INIT_LIST_HEAD(&dev->slist);
  76         mutex_init(&dev->mutex);
  77
  78         memcpy(&dev->dev, device, sizeof(struct device));
  79         dev_set_name(&dev->dev, "w1_bus_master%u", dev->id);
  80         snprintf(dev->name, sizeof(dev->name), "w1_bus_master%u", dev->id);
  81
  82         dev->driver = driver;
  83
  84         dev->seq = 1;
  85
  86         err = device_register(&dev->dev);
  87         if (err) {
  88                 printk(KERN_ERR "Failed to register master device. err=%d\n", err);
  89                 memset(dev, 0, sizeof(struct w1_master));
  90                 kfree(dev);
  91                 dev = NULL;
  92         }
  93
  94         return dev;
  95 }
  96
  97 static void w1_free_dev(struct w1_master *dev)
  98 {
  99         device_unregister(&dev->dev);
 100 }
 101
 102 int 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                 printk(KERN_ERR "w1_add_master_device: invalid function set\n");
 114                 return(-EINVAL);
 115         }
 116         /* While it would be electrically possible to make a device that
 117          * generated a strong pullup in bit bang mode, only hardare that
 118          * controls 1-wire time frames are even expected to support a strong
 119          * pullup.  w1_io.c would need to support calling set_pullup before
 120          * the last write_bit operation of a w1_write_8 which it currently
 121          * doesn't.
 122          */
 123         if (!master->write_byte && !master->touch_bit && master->set_pullup) {
 124                 printk(KERN_ERR "w1_add_master_device: set_pullup requires "
 125                         "write_byte or touch_bit, disabling\n");
 126                 master->set_pullup = NULL;
 127         }
 128
 129         /* Lock until the device is added (or not) to w1_masters. */
 130         mutex_lock(&w1_mlock);
 131         /* Search for the first available id (starting at 1). */
 132         id = 0;
 133         do {
 134                 ++id;
 135                 found = 0;
 136                 list_for_each_entry(entry, &w1_masters, w1_master_entry) {
 137                         if (entry->id == id) {
 138                                 found = 1;
 139                                 break;
 140                         }
 141                 }
 142         } while (found);
 143
 144         dev = w1_alloc_dev(id, w1_max_slave_count, w1_max_slave_ttl,
 145                 &w1_master_driver, &w1_master_device);
 146         if (!dev) {
 147                 mutex_unlock(&w1_mlock);
 148                 return -ENOMEM;
 149         }
 150
 151         retval =  w1_create_master_attributes(dev);
 152         if (retval) {
 153                 mutex_unlock(&w1_mlock);
 154                 goto err_out_free_dev;
 155         }
 156
 157         memcpy(dev->bus_master, master, sizeof(struct w1_bus_master));
 158
 159         dev->initialized = 1;
 160
 161         dev->thread = kthread_run(&w1_process, dev, "%s", dev->name);
 162         if (IS_ERR(dev->thread)) {
 163                 retval = PTR_ERR(dev->thread);
 164                 dev_err(&dev->dev,
 165                          "Failed to create new kernel thread. err=%d\n",
 166                          retval);
 167                 mutex_unlock(&w1_mlock);
 168                 goto err_out_rm_attr;
 169         }
 170
 171         list_add(&dev->w1_master_entry, &w1_masters);
 172         mutex_unlock(&w1_mlock);
 173
 174         memset(&msg, 0, sizeof(msg));
 175         msg.id.mst.id = dev->id;
 176         msg.type = W1_MASTER_ADD;
 177         w1_netlink_send(dev, &msg);
 178
 179         return 0;
 180
 181 #if 0 /* Thread cleanup code, not required currently. */
 182 err_out_kill_thread:
 183         kthread_stop(dev->thread);
 184 #endif
 185 err_out_rm_attr:
 186         w1_destroy_master_attributes(dev);
 187 err_out_free_dev:
 188         w1_free_dev(dev);
 189
 190         return retval;
 191 }
 192
 193 void __w1_remove_master_device(struct w1_master *dev)
 194 {
 195         struct w1_netlink_msg msg;
 196         struct w1_slave *sl, *sln;
 197
 198         kthread_stop(dev->thread);
 199
 200         mutex_lock(&w1_mlock);
 201         list_del(&dev->w1_master_entry);
 202         mutex_unlock(&w1_mlock);
 203
 204         mutex_lock(&dev->mutex);
 205         list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry)
 206                 w1_slave_detach(sl);
 207         w1_destroy_master_attributes(dev);
 208         mutex_unlock(&dev->mutex);
 209         atomic_dec(&dev->refcnt);
 210
 211         while (atomic_read(&dev->refcnt)) {
 212                 dev_info(&dev->dev, "Waiting for %s to become free: refcnt=%d.\n",
 213                                 dev->name, atomic_read(&dev->refcnt));
 214
 215                 if (msleep_interruptible(1000))
 216                         flush_signals(current);
 217         }
 218
 219         memset(&msg, 0, sizeof(msg));
 220         msg.id.mst.id = dev->id;
 221         msg.type = W1_MASTER_REMOVE;
 222         w1_netlink_send(dev, &msg);
 223
 224         w1_free_dev(dev);
 225 }
 226
 227 void w1_remove_master_device(struct w1_bus_master *bm)
 228 {
 229         struct w1_master *dev, *found = NULL;
 230
 231         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
 232                 if (!dev->initialized)
 233                         continue;
 234
 235                 if (dev->bus_master->data == bm->data) {
 236                         found = dev;
 237                         break;
 238                 }
 239         }
 240
 241         if (!found) {
 242                 printk(KERN_ERR "Device doesn't exist.\n");
 243                 return;
 244         }
 245
 246         __w1_remove_master_device(found);
 247 }
 248
 249 EXPORT_SYMBOL(w1_add_master_device);
 250 EXPORT_SYMBOL(w1_remove_master_device);