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
  29 #include "w1.h"
  30 #include "w1_log.h"
  31 #include "w1_netlink.h"
  32 #include "w1_int.h"
  33
  34 static int w1_search_count = -1; /* Default is continual scan */
  35 module_param_named(search_count, w1_search_count, int, 0);
  36
  37 static int w1_enable_pullup = 1;
  38 module_param_named(enable_pullup, w1_enable_pullup, int, 0);
  39
  40 static struct w1_master * w1_alloc_dev(u32 id, int slave_count, int slave_ttl,
  41                                        struct device_driver *driver,
  42                                        struct device *device)
  43 {
  44         struct w1_master *dev;
  45         int err;
  46
  47         /*
  48          * We are in process context(kernel thread), so can sleep.
  49          */
  50         dev = kzalloc(sizeof(struct w1_master) + sizeof(struct w1_bus_master), GFP_KERNEL);
  51         if (!dev) {
  52                 printk(KERN_ERR
  53                         "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         mutex_init(&dev->mutex);
  78
  79         memcpy(&dev->dev, device, sizeof(struct device));
  80         dev_set_name(&dev->dev, "w1_bus_master%u", dev->id);
  81         snprintf(dev->name, sizeof(dev->name), "w1_bus_master%u", dev->id);
  82
  83         dev->driver = driver;
  84
  85         dev->seq = 1;
  86
  87         err = device_register(&dev->dev);
  88         if (err) {
  89                 printk(KERN_ERR "Failed to register master device. err=%d\n", err);
  90                 memset(dev, 0, sizeof(struct w1_master));
  91                 kfree(dev);
  92                 dev = NULL;
  93         }
  94
  95         return dev;
  96 }
  97
  98 static void w1_free_dev(struct w1_master *dev)
  99 {
 100         device_unregister(&dev->dev);
 101 }
 102
 103 int w1_add_master_device(struct w1_bus_master *master)
 104 {
 105         struct w1_master *dev, *entry;
 106         int retval = 0;
 107         struct w1_netlink_msg msg;
 108         int id, found;
 109
 110         /* validate minimum functionality */
 111         if (!(master->touch_bit && master->reset_bus) &&
 112             !(master->write_bit && master->read_bit) &&
 113             !(master->write_byte && master->read_byte && master->reset_bus)) {
 114                 printk(KERN_ERR "w1_add_master_device: invalid function set\n");
 115                 return(-EINVAL);
 116         }
 117         /* While it would be electrically possible to make a device that
 118          * generated a strong pullup in bit bang mode, only hardare that
 119          * controls 1-wire time frames are even expected to support a strong
 120          * pullup.  w1_io.c would need to support calling set_pullup before
 121          * the last write_bit operation of a w1_write_8 which it currently
 122          * doesn't.
 123          */
 124         if (!master->write_byte && !master->touch_bit && master->set_pullup) {
 125                 printk(KERN_ERR "w1_add_master_device: set_pullup requires "
 126                         "write_byte or touch_bit, disabling\n");
 127                 master->set_pullup = NULL;
 128         }
 129
 130         /* Lock until the device is added (or not) to w1_masters. */
 131         mutex_lock(&w1_mlock);
 132         /* Search for the first available id (starting at 1). */
 133         id = 0;
 134         do {
 135                 ++id;
 136                 found = 0;
 137                 list_for_each_entry(entry, &w1_masters, w1_master_entry) {
 138                         if (entry->id == id) {
 139                                 found = 1;
 140                                 break;
 141                         }
 142                 }
 143         } while (found);
 144
 145         dev = w1_alloc_dev(id, w1_max_slave_count, w1_max_slave_ttl,
 146                 &w1_master_driver, &w1_master_device);
 147         if (!dev) {
 148                 mutex_unlock(&w1_mlock);
 149                 return -ENOMEM;
 150         }
 151
 152         retval =  w1_create_master_attributes(dev);
 153         if (retval) {
 154                 mutex_unlock(&w1_mlock);
 155                 goto err_out_free_dev;
 156         }
 157
 158         memcpy(dev->bus_master, master, sizeof(struct w1_bus_master));
 159
 160         dev->initialized = 1;
 161
 162         dev->thread = kthread_run(&w1_process, dev, "%s", dev->name);
 163         if (IS_ERR(dev->thread)) {
 164                 retval = PTR_ERR(dev->thread);
 165                 dev_err(&dev->dev,
 166                          "Failed to create new kernel thread. err=%d\n",
 167                          retval);
 168                 mutex_unlock(&w1_mlock);
 169                 goto err_out_rm_attr;
 170         }
 171
 172         list_add(&dev->w1_master_entry, &w1_masters);
 173         mutex_unlock(&w1_mlock);
 174
 175         memset(&msg, 0, sizeof(msg));
 176         msg.id.mst.id = dev->id;
 177         msg.type = W1_MASTER_ADD;
 178         w1_netlink_send(dev, &msg);
 179
 180         return 0;
 181
 182 #if 0 /* Thread cleanup code, not required currently. */
 183 err_out_kill_thread:
 184         kthread_stop(dev->thread);
 185 #endif
 186 err_out_rm_attr:
 187         w1_destroy_master_attributes(dev);
 188 err_out_free_dev:
 189         w1_free_dev(dev);
 190
 191         return retval;
 192 }
 193
 194 void __w1_remove_master_device(struct w1_master *dev)
 195 {
 196         struct w1_netlink_msg msg;
 197         struct w1_slave *sl, *sln;
 198
 199         kthread_stop(dev->thread);
 200
 201         mutex_lock(&w1_mlock);
 202         list_del(&dev->w1_master_entry);
 203         mutex_unlock(&w1_mlock);
 204
 205         mutex_lock(&dev->mutex);
 206         list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry)
 207                 w1_slave_detach(sl);
 208         w1_destroy_master_attributes(dev);
 209         mutex_unlock(&dev->mutex);
 210         atomic_dec(&dev->refcnt);
 211
 212         while (atomic_read(&dev->refcnt)) {
 213                 dev_info(&dev->dev, "Waiting for %s to become free: refcnt=%d.\n",
 214                                 dev->name, atomic_read(&dev->refcnt));
 215
 216                 if (msleep_interruptible(1000))
 217                         flush_signals(current);
 218         }
 219
 220         memset(&msg, 0, sizeof(msg));
 221         msg.id.mst.id = dev->id;
 222         msg.type = W1_MASTER_REMOVE;
 223         w1_netlink_send(dev, &msg);
 224
 225         w1_free_dev(dev);
 226 }
 227
 228 void w1_remove_master_device(struct w1_bus_master *bm)
 229 {
 230         struct w1_master *dev, *found = NULL;
 231
 232         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
 233                 if (!dev->initialized)
 234                         continue;
 235
 236                 if (dev->bus_master->data == bm->data) {
 237                         found = dev;
 238                         break;
 239                 }
 240         }
 241
 242         if (!found) {
 243                 printk(KERN_ERR "Device doesn't exist.\n");
 244                 return;
 245         }
 246
 247         __w1_remove_master_device(found);
 248 }
 249
 250 EXPORT_SYMBOL(w1_add_master_device);
 251 EXPORT_SYMBOL(w1_remove_master_device);