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
  34 static struct w1_master * w1_alloc_dev(u32 id, int slave_count, int slave_ttl,
  35                                        struct device_driver *driver,
  36                                        struct device *device)
  37 {
  38         struct w1_master *dev;
  39         int err;
  40
  41         /*
  42          * We are in process context(kernel thread), so can sleep.
  43          */
  44         dev = kzalloc(sizeof(struct w1_master) + sizeof(struct w1_bus_master), GFP_KERNEL);
  45         if (!dev) {
  46                 printk(KERN_ERR
  47                         "Failed to allocate %zd bytes for new w1 device.\n",
  48                         sizeof(struct w1_master));
  49                 return NULL;
  50         }
  51
  52
  53         dev->bus_master = (struct w1_bus_master *)(dev + 1);
  54
  55         dev->owner              = THIS_MODULE;
  56         dev->max_slave_count    = slave_count;
  57         dev->slave_count        = 0;
  58         dev->attempts           = 0;
  59         dev->initialized        = 0;
  60         dev->id                 = id;
  61         dev->slave_ttl          = slave_ttl;
  62         dev->search_count       = -1; /* continual scan */
  63
  64         /* 1 for w1_process to decrement
  65          * 1 for __w1_remove_master_device to decrement
  66          */
  67         atomic_set(&dev->refcnt, 2);
  68
  69         INIT_LIST_HEAD(&dev->slist);
  70         mutex_init(&dev->mutex);
  71
  72         memcpy(&dev->dev, device, sizeof(struct device));
  73         snprintf(dev->dev.bus_id, sizeof(dev->dev.bus_id),
  74                   "w1_bus_master%u", dev->id);
  75         snprintf(dev->name, sizeof(dev->name), "w1_bus_master%u", dev->id);
  76
  77         dev->driver = driver;
  78
  79         dev->seq = 1;
  80
  81         err = device_register(&dev->dev);
  82         if (err) {
  83                 printk(KERN_ERR "Failed to register master device. err=%d\n", err);
  84                 memset(dev, 0, sizeof(struct w1_master));
  85                 kfree(dev);
  86                 dev = NULL;
  87         }
  88
  89         return dev;
  90 }
  91
  92 static void w1_free_dev(struct w1_master *dev)
  93 {
  94         device_unregister(&dev->dev);
  95 }
  96
  97 int w1_add_master_device(struct w1_bus_master *master)
  98 {
  99         struct w1_master *dev;
 100         int retval = 0;
 101         struct w1_netlink_msg msg;
 102
 103         /* validate minimum functionality */
 104         if (!(master->touch_bit && master->reset_bus) &&
 105             !(master->write_bit && master->read_bit) &&
 106             !(master->write_byte && master->read_byte && master->reset_bus)) {
 107                 printk(KERN_ERR "w1_add_master_device: invalid function set\n");
 108                 return(-EINVAL);
 109         }
 110
 111         dev = w1_alloc_dev(w1_ids++, w1_max_slave_count, w1_max_slave_ttl, &w1_master_driver, &w1_master_device);
 112         if (!dev)
 113                 return -ENOMEM;
 114
 115         retval =  w1_create_master_attributes(dev);
 116         if (retval)
 117                 goto err_out_free_dev;
 118
 119         memcpy(dev->bus_master, master, sizeof(struct w1_bus_master));
 120
 121         dev->initialized = 1;
 122
 123         dev->thread = kthread_run(&w1_process, dev, "%s", dev->name);
 124         if (IS_ERR(dev->thread)) {
 125                 retval = PTR_ERR(dev->thread);
 126                 dev_err(&dev->dev,
 127                          "Failed to create new kernel thread. err=%d\n",
 128                          retval);
 129                 goto err_out_rm_attr;
 130         }
 131
 132         mutex_lock(&w1_mlock);
 133         list_add(&dev->w1_master_entry, &w1_masters);
 134         mutex_unlock(&w1_mlock);
 135
 136         memset(&msg, 0, sizeof(msg));
 137         msg.id.mst.id = dev->id;
 138         msg.type = W1_MASTER_ADD;
 139         w1_netlink_send(dev, &msg);
 140
 141         return 0;
 142
 143 #if 0 /* Thread cleanup code, not required currently. */
 144 err_out_kill_thread:
 145         kthread_stop(dev->thread);
 146 #endif
 147 err_out_rm_attr:
 148         w1_destroy_master_attributes(dev);
 149 err_out_free_dev:
 150         w1_free_dev(dev);
 151
 152         return retval;
 153 }
 154
 155 void __w1_remove_master_device(struct w1_master *dev)
 156 {
 157         struct w1_netlink_msg msg;
 158         struct w1_slave *sl, *sln;
 159
 160         kthread_stop(dev->thread);
 161
 162         mutex_lock(&w1_mlock);
 163         list_del(&dev->w1_master_entry);
 164         mutex_unlock(&w1_mlock);
 165
 166         mutex_lock(&dev->mutex);
 167         list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry)
 168                 w1_slave_detach(sl);
 169         w1_destroy_master_attributes(dev);
 170         mutex_unlock(&dev->mutex);
 171         atomic_dec(&dev->refcnt);
 172
 173         while (atomic_read(&dev->refcnt)) {
 174                 dev_info(&dev->dev, "Waiting for %s to become free: refcnt=%d.\n",
 175                                 dev->name, atomic_read(&dev->refcnt));
 176
 177                 if (msleep_interruptible(1000))
 178                         flush_signals(current);
 179         }
 180
 181         memset(&msg, 0, sizeof(msg));
 182         msg.id.mst.id = dev->id;
 183         msg.type = W1_MASTER_REMOVE;
 184         w1_netlink_send(dev, &msg);
 185
 186         w1_free_dev(dev);
 187 }
 188
 189 void w1_remove_master_device(struct w1_bus_master *bm)
 190 {
 191         struct w1_master *dev, *found = NULL;
 192
 193         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
 194                 if (!dev->initialized)
 195                         continue;
 196
 197                 if (dev->bus_master->data == bm->data) {
 198                         found = dev;
 199                         break;
 200                 }
 201         }
 202
 203         if (!found) {
 204                 printk(KERN_ERR "Device doesn't exist.\n");
 205                 return;
 206         }
 207
 208         __w1_remove_master_device(found);
 209 }
 210
 211 EXPORT_SYMBOL(w1_add_master_device);
 212 EXPORT_SYMBOL(w1_remove_master_device);