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