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
  80         memcpy(&dev->dev, device, sizeof(struct device));
  81         dev_set_name(&dev->dev, "w1_bus_master%u", dev->id);
  82         snprintf(dev->name, sizeof(dev->name), "w1_bus_master%u", dev->id);
  83         dev->dev.init_name = dev->name;
  84
  85         dev->driver = driver;
  86
  87         dev->seq = 1;
  88
  89         err = device_register(&dev->dev);
  90         if (err) {
  91                 printk(KERN_ERR "Failed to register master device. err=%d\n", err);
  92                 memset(dev, 0, sizeof(struct w1_master));
  93                 kfree(dev);
  94                 dev = NULL;
  95         }
  96
  97         return dev;
  98 }
  99
 100 static void w1_free_dev(struct w1_master *dev)
 101 {
 102         device_unregister(&dev->dev);
 103 }
 104
 105 int w1_add_master_device(struct w1_bus_master *master)
 106 {
 107         struct w1_master *dev, *entry;
 108         int retval = 0;
 109         struct w1_netlink_msg msg;
 110         int id, found;
 111
 112         /* validate minimum functionality */
 113         if (!(master->touch_bit && master->reset_bus) &&
 114             !(master->write_bit && master->read_bit) &&
 115             !(master->write_byte && master->read_byte && master->reset_bus)) {
 116                 printk(KERN_ERR "w1_add_master_device: invalid function set\n");
 117                 return(-EINVAL);
 118         }
 119         /* While it would be electrically possible to make a device that
 120          * generated a strong pullup in bit bang mode, only hardare that
 121          * controls 1-wire time frames are even expected to support a strong
 122          * pullup.  w1_io.c would need to support calling set_pullup before
 123          * the last write_bit operation of a w1_write_8 which it currently
 124          * doesn't.
 125          */
 126         if (!master->write_byte && !master->touch_bit && master->set_pullup) {
 127                 printk(KERN_ERR "w1_add_master_device: set_pullup requires "
 128                         "write_byte or touch_bit, disabling\n");
 129                 master->set_pullup = NULL;
 130         }
 131
 132         /* Lock until the device is added (or not) to w1_masters. */
 133         mutex_lock(&w1_mlock);
 134         /* Search for the first available id (starting at 1). */
 135         id = 0;
 136         do {
 137                 ++id;
 138                 found = 0;
 139                 list_for_each_entry(entry, &w1_masters, w1_master_entry) {
 140                         if (entry->id == id) {
 141                                 found = 1;
 142                                 break;
 143                         }
 144                 }
 145         } while (found);
 146
 147         dev = w1_alloc_dev(id, w1_max_slave_count, w1_max_slave_ttl,
 148                 &w1_master_driver, &w1_master_device);
 149         if (!dev) {
 150                 mutex_unlock(&w1_mlock);
 151                 return -ENOMEM;
 152         }
 153
 154         retval =  w1_create_master_attributes(dev);
 155         if (retval) {
 156                 mutex_unlock(&w1_mlock);
 157                 goto err_out_free_dev;
 158         }
 159
 160         memcpy(dev->bus_master, master, sizeof(struct w1_bus_master));
 161
 162         dev->initialized = 1;
 163
 164         dev->thread = kthread_run(&w1_process, dev, "%s", dev->name);
 165         if (IS_ERR(dev->thread)) {
 166                 retval = PTR_ERR(dev->thread);
 167                 dev_err(&dev->dev,
 168                          "Failed to create new kernel thread. err=%d\n",
 169                          retval);
 170                 mutex_unlock(&w1_mlock);
 171                 goto err_out_rm_attr;
 172         }
 173
 174         list_add(&dev->w1_master_entry, &w1_masters);
 175         mutex_unlock(&w1_mlock);
 176
 177         memset(&msg, 0, sizeof(msg));
 178         msg.id.mst.id = dev->id;
 179         msg.type = W1_MASTER_ADD;
 180         w1_netlink_send(dev, &msg);
 181
 182         return 0;
 183
 184 #if 0 /* Thread cleanup code, not required currently. */
 185 err_out_kill_thread:
 186         kthread_stop(dev->thread);
 187 #endif
 188 err_out_rm_attr:
 189         w1_destroy_master_attributes(dev);
 190 err_out_free_dev:
 191         w1_free_dev(dev);
 192
 193         return retval;
 194 }
 195
 196 void __w1_remove_master_device(struct w1_master *dev)
 197 {
 198         struct w1_netlink_msg msg;
 199         struct w1_slave *sl, *sln;
 200
 201         kthread_stop(dev->thread);
 202
 203         mutex_lock(&w1_mlock);
 204         list_del(&dev->w1_master_entry);
 205         mutex_unlock(&w1_mlock);
 206
 207         mutex_lock(&dev->mutex);
 208         list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry)
 209                 w1_slave_detach(sl);
 210         w1_destroy_master_attributes(dev);
 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         }
 221
 222         memset(&msg, 0, sizeof(msg));
 223         msg.id.mst.id = dev->id;
 224         msg.type = W1_MASTER_REMOVE;
 225         w1_netlink_send(dev, &msg);
 226
 227         w1_free_dev(dev);
 228 }
 229
 230 void w1_remove_master_device(struct w1_bus_master *bm)
 231 {
 232         struct w1_master *dev, *found = NULL;
 233
 234         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
 235                 if (!dev->initialized)
 236                         continue;
 237
 238                 if (dev->bus_master->data == bm->data) {
 239                         found = dev;
 240                         break;
 241                 }
 242         }
 243
 244         if (!found) {
 245                 printk(KERN_ERR "Device doesn't exist.\n");
 246                 return;
 247         }
 248
 249         __w1_remove_master_device(found);
 250 }
 251
 252 EXPORT_SYMBOL(w1_add_master_device);
 253 EXPORT_SYMBOL(w1_remove_master_device);