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 = kmalloc(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         memset(dev, 0, sizeof(struct w1_master) + sizeof(struct w1_bus_master));
  53
  54         dev->bus_master = (struct w1_bus_master *)(dev + 1);
  55
  56         dev->owner              = THIS_MODULE;
  57         dev->max_slave_count    = slave_count;
  58         dev->slave_count        = 0;
  59         dev->attempts           = 0;
  60         dev->initialized        = 0;
  61         dev->id                 = id;
  62         dev->slave_ttl          = slave_ttl;
  63         dev->search_count       = -1; /* continual scan */
  64
  65         atomic_set(&dev->refcnt, 2);
  66
  67         INIT_LIST_HEAD(&dev->slist);
  68         init_MUTEX(&dev->mutex);
  69
  70         memcpy(&dev->dev, device, sizeof(struct device));
  71         snprintf(dev->dev.bus_id, sizeof(dev->dev.bus_id),
  72                   "w1_bus_master%u", dev->id);
  73         snprintf(dev->name, sizeof(dev->name), "w1_bus_master%u", dev->id);
  74
  75         dev->driver = driver;
  76
  77         dev->groups = 1;
  78         dev->seq = 1;
  79         dev_init_netlink(dev);
  80
  81         err = device_register(&dev->dev);
  82         if (err) {
  83                 printk(KERN_ERR "Failed to register master device. err=%d\n", err);
  84
  85                 dev_fini_netlink(dev);
  86
  87                 memset(dev, 0, sizeof(struct w1_master));
  88                 kfree(dev);
  89                 dev = NULL;
  90         }
  91
  92         return dev;
  93 }
  94
  95 static void w1_free_dev(struct w1_master *dev)
  96 {
  97         device_unregister(&dev->dev);
  98 }
  99
 100 int w1_add_master_device(struct w1_bus_master *master)
 101 {
 102         struct w1_master *dev;
 103         int retval = 0;
 104         struct w1_netlink_msg msg;
 105
 106         /* validate minimum functionality */
 107         if (!(master->touch_bit && master->reset_bus) &&
 108             !(master->write_bit && master->read_bit)) {
 109                 printk(KERN_ERR "w1_add_master_device: invalid function set\n");
 110                 return(-EINVAL);
 111         }
 112
 113         dev = w1_alloc_dev(w1_ids++, w1_max_slave_count, w1_max_slave_ttl, &w1_master_driver, &w1_master_device);
 114         if (!dev)
 115                 return -ENOMEM;
 116
 117         dev->thread = kthread_run(&w1_process, dev, "%s", dev->name);
 118         if (IS_ERR(dev->thread)) {
 119                 retval = PTR_ERR(dev->thread);
 120                 dev_err(&dev->dev,
 121                          "Failed to create new kernel thread. err=%d\n",
 122                          retval);
 123                 goto err_out_free_dev;
 124         }
 125
 126         retval =  w1_create_master_attributes(dev);
 127         if (retval)
 128                 goto err_out_kill_thread;
 129
 130         memcpy(dev->bus_master, master, sizeof(struct w1_bus_master));
 131
 132         dev->initialized = 1;
 133
 134         spin_lock(&w1_mlock);
 135         list_add(&dev->w1_master_entry, &w1_masters);
 136         spin_unlock(&w1_mlock);
 137
 138         msg.id.mst.id = dev->id;
 139         msg.id.mst.pid = dev->thread->pid;
 140         msg.type = W1_MASTER_ADD;
 141         w1_netlink_send(dev, &msg);
 142
 143         return 0;
 144
 145 err_out_kill_thread:
 146         kthread_stop(dev->thread);
 147 err_out_free_dev:
 148         w1_free_dev(dev);
 149
 150         return retval;
 151 }
 152
 153 void __w1_remove_master_device(struct w1_master *dev)
 154 {
 155         struct w1_netlink_msg msg;
 156         pid_t pid = dev->thread->pid;
 157
 158         set_bit(W1_MASTER_NEED_EXIT, &dev->flags);
 159         kthread_stop(dev->thread);
 160
 161         while (atomic_read(&dev->refcnt)) {
 162                 dev_info(&dev->dev, "Waiting for %s to become free: refcnt=%d.\n",
 163                                 dev->name, atomic_read(&dev->refcnt));
 164
 165                 if (msleep_interruptible(1000))
 166                         flush_signals(current);
 167         }
 168
 169         msg.id.mst.id = dev->id;
 170         msg.id.mst.pid = pid;
 171         msg.type = W1_MASTER_REMOVE;
 172         w1_netlink_send(dev, &msg);
 173
 174         w1_free_dev(dev);
 175 }
 176
 177 void w1_remove_master_device(struct w1_bus_master *bm)
 178 {
 179         struct w1_master *dev = NULL;
 180
 181         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
 182                 if (!dev->initialized)
 183                         continue;
 184
 185                 if (dev->bus_master->data == bm->data)
 186                         break;
 187         }
 188
 189         if (!dev) {
 190                 printk(KERN_ERR "Device doesn't exist.\n");
 191                 return;
 192         }
 193
 194         __w1_remove_master_device(dev);
 195 }
 196
 197 EXPORT_SYMBOL(w1_add_master_device);
 198 EXPORT_SYMBOL(w1_remove_master_device);