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 u32 w1_ids = 1;
  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         snprintf(dev->dev.bus_id, sizeof(dev->dev.bus_id),
  80                   "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;
 106         int retval = 0;
 107         struct w1_netlink_msg msg;
 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         dev = w1_alloc_dev(w1_ids++, w1_max_slave_count, w1_max_slave_ttl, &w1_master_driver, &w1_master_device);
 130         if (!dev)
 131                 return -ENOMEM;
 132
 133         retval =  w1_create_master_attributes(dev);
 134         if (retval)
 135                 goto err_out_free_dev;
 136
 137         memcpy(dev->bus_master, master, sizeof(struct w1_bus_master));
 138
 139         dev->initialized = 1;
 140
 141         dev->thread = kthread_run(&w1_process, dev, "%s", dev->name);
 142         if (IS_ERR(dev->thread)) {
 143                 retval = PTR_ERR(dev->thread);
 144                 dev_err(&dev->dev,
 145                          "Failed to create new kernel thread. err=%d\n",
 146                          retval);
 147                 goto err_out_rm_attr;
 148         }
 149
 150         mutex_lock(&w1_mlock);
 151         list_add(&dev->w1_master_entry, &w1_masters);
 152         mutex_unlock(&w1_mlock);
 153
 154         memset(&msg, 0, sizeof(msg));
 155         msg.id.mst.id = dev->id;
 156         msg.type = W1_MASTER_ADD;
 157         w1_netlink_send(dev, &msg);
 158
 159         return 0;
 160
 161 #if 0 /* Thread cleanup code, not required currently. */
 162 err_out_kill_thread:
 163         kthread_stop(dev->thread);
 164 #endif
 165 err_out_rm_attr:
 166         w1_destroy_master_attributes(dev);
 167 err_out_free_dev:
 168         w1_free_dev(dev);
 169
 170         return retval;
 171 }
 172
 173 void __w1_remove_master_device(struct w1_master *dev)
 174 {
 175         struct w1_netlink_msg msg;
 176         struct w1_slave *sl, *sln;
 177
 178         kthread_stop(dev->thread);
 179
 180         mutex_lock(&w1_mlock);
 181         list_del(&dev->w1_master_entry);
 182         mutex_unlock(&w1_mlock);
 183
 184         mutex_lock(&dev->mutex);
 185         list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry)
 186                 w1_slave_detach(sl);
 187         w1_destroy_master_attributes(dev);
 188         mutex_unlock(&dev->mutex);
 189         atomic_dec(&dev->refcnt);
 190
 191         while (atomic_read(&dev->refcnt)) {
 192                 dev_info(&dev->dev, "Waiting for %s to become free: refcnt=%d.\n",
 193                                 dev->name, atomic_read(&dev->refcnt));
 194
 195                 if (msleep_interruptible(1000))
 196                         flush_signals(current);
 197         }
 198
 199         memset(&msg, 0, sizeof(msg));
 200         msg.id.mst.id = dev->id;
 201         msg.type = W1_MASTER_REMOVE;
 202         w1_netlink_send(dev, &msg);
 203
 204         w1_free_dev(dev);
 205 }
 206
 207 void w1_remove_master_device(struct w1_bus_master *bm)
 208 {
 209         struct w1_master *dev, *found = NULL;
 210
 211         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
 212                 if (!dev->initialized)
 213                         continue;
 214
 215                 if (dev->bus_master->data == bm->data) {
 216                         found = dev;
 217                         break;
 218                 }
 219         }
 220
 221         if (!found) {
 222                 printk(KERN_ERR "Device doesn't exist.\n");
 223                 return;
 224         }
 225
 226         __w1_remove_master_device(found);
 227 }
 228
 229 EXPORT_SYMBOL(w1_add_master_device);
 230 EXPORT_SYMBOL(w1_remove_master_device);