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 int w1_enable_pullup = 1;
  35 module_param_named(enable_pullup, w1_enable_pullup, int, 0);
  36
  37 static struct w1_master * w1_alloc_dev(u32 id, int slave_count, int slave_ttl,
  38                                        struct device_driver *driver,
  39                                        struct device *device)
  40 {
  41         struct w1_master *dev;
  42         int err;
  43
  44         /*
  45          * We are in process context(kernel thread), so can sleep.
  46          */
  47         dev = kzalloc(sizeof(struct w1_master) + sizeof(struct w1_bus_master), GFP_KERNEL);
  48         if (!dev) {
  49                 printk(KERN_ERR
  50                         "Failed to allocate %zd bytes for new w1 device.\n",
  51                         sizeof(struct w1_master));
  52                 return NULL;
  53         }
  54
  55
  56         dev->bus_master = (struct w1_bus_master *)(dev + 1);
  57
  58         dev->owner              = THIS_MODULE;
  59         dev->max_slave_count    = slave_count;
  60         dev->slave_count        = 0;
  61         dev->attempts           = 0;
  62         dev->initialized        = 0;
  63         dev->id                 = id;
  64         dev->slave_ttl          = slave_ttl;
  65         dev->enable_pullup      = w1_enable_pullup;
  66         dev->search_count       = -1; /* continual scan */
  67
  68         /* 1 for w1_process to decrement
  69          * 1 for __w1_remove_master_device to decrement
  70          */
  71         atomic_set(&dev->refcnt, 2);
  72
  73         INIT_LIST_HEAD(&dev->slist);
  74         mutex_init(&dev->mutex);
  75
  76         memcpy(&dev->dev, device, sizeof(struct device));
  77         snprintf(dev->dev.bus_id, sizeof(dev->dev.bus_id),
  78                   "w1_bus_master%u", dev->id);
  79         snprintf(dev->name, sizeof(dev->name), "w1_bus_master%u", dev->id);
  80
  81         dev->driver = driver;
  82
  83         dev->seq = 1;
  84
  85         err = device_register(&dev->dev);
  86         if (err) {
  87                 printk(KERN_ERR "Failed to register master device. err=%d\n", err);
  88                 memset(dev, 0, sizeof(struct w1_master));
  89                 kfree(dev);
  90                 dev = NULL;
  91         }
  92
  93         return dev;
  94 }
  95
  96 static void w1_free_dev(struct w1_master *dev)
  97 {
  98         device_unregister(&dev->dev);
  99 }
 100
 101 int w1_add_master_device(struct w1_bus_master *master)
 102 {
 103         struct w1_master *dev;
 104         int retval = 0;
 105         struct w1_netlink_msg msg;
 106
 107         /* validate minimum functionality */
 108         if (!(master->touch_bit && master->reset_bus) &&
 109             !(master->write_bit && master->read_bit) &&
 110             !(master->write_byte && master->read_byte && master->reset_bus)) {
 111                 printk(KERN_ERR "w1_add_master_device: invalid function set\n");
 112                 return(-EINVAL);
 113         }
 114         /* While it would be electrically possible to make a device that
 115          * generated a strong pullup in bit bang mode, only hardare that
 116          * controls 1-wire time frames are even expected to support a strong
 117          * pullup.  w1_io.c would need to support calling set_pullup before
 118          * the last write_bit operation of a w1_write_8 which it currently
 119          * doesn't.
 120          */
 121         if (!master->write_byte && !master->touch_bit && master->set_pullup) {
 122                 printk(KERN_ERR "w1_add_master_device: set_pullup requires "
 123                         "write_byte or touch_bit, disabling\n");
 124                 master->set_pullup = NULL;
 125         }
 126
 127         dev = w1_alloc_dev(w1_ids++, w1_max_slave_count, w1_max_slave_ttl, &w1_master_driver, &w1_master_device);
 128         if (!dev)
 129                 return -ENOMEM;
 130
 131         retval =  w1_create_master_attributes(dev);
 132         if (retval)
 133                 goto err_out_free_dev;
 134
 135         memcpy(dev->bus_master, master, sizeof(struct w1_bus_master));
 136
 137         dev->initialized = 1;
 138
 139         dev->thread = kthread_run(&w1_process, dev, "%s", dev->name);
 140         if (IS_ERR(dev->thread)) {
 141                 retval = PTR_ERR(dev->thread);
 142                 dev_err(&dev->dev,
 143                          "Failed to create new kernel thread. err=%d\n",
 144                          retval);
 145                 goto err_out_rm_attr;
 146         }
 147
 148         mutex_lock(&w1_mlock);
 149         list_add(&dev->w1_master_entry, &w1_masters);
 150         mutex_unlock(&w1_mlock);
 151
 152         memset(&msg, 0, sizeof(msg));
 153         msg.id.mst.id = dev->id;
 154         msg.type = W1_MASTER_ADD;
 155         w1_netlink_send(dev, &msg);
 156
 157         return 0;
 158
 159 #if 0 /* Thread cleanup code, not required currently. */
 160 err_out_kill_thread:
 161         kthread_stop(dev->thread);
 162 #endif
 163 err_out_rm_attr:
 164         w1_destroy_master_attributes(dev);
 165 err_out_free_dev:
 166         w1_free_dev(dev);
 167
 168         return retval;
 169 }
 170
 171 void __w1_remove_master_device(struct w1_master *dev)
 172 {
 173         struct w1_netlink_msg msg;
 174         struct w1_slave *sl, *sln;
 175
 176         kthread_stop(dev->thread);
 177
 178         mutex_lock(&w1_mlock);
 179         list_del(&dev->w1_master_entry);
 180         mutex_unlock(&w1_mlock);
 181
 182         mutex_lock(&dev->mutex);
 183         list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry)
 184                 w1_slave_detach(sl);
 185         w1_destroy_master_attributes(dev);
 186         mutex_unlock(&dev->mutex);
 187         atomic_dec(&dev->refcnt);
 188
 189         while (atomic_read(&dev->refcnt)) {
 190                 dev_info(&dev->dev, "Waiting for %s to become free: refcnt=%d.\n",
 191                                 dev->name, atomic_read(&dev->refcnt));
 192
 193                 if (msleep_interruptible(1000))
 194                         flush_signals(current);
 195         }
 196
 197         memset(&msg, 0, sizeof(msg));
 198         msg.id.mst.id = dev->id;
 199         msg.type = W1_MASTER_REMOVE;
 200         w1_netlink_send(dev, &msg);
 201
 202         w1_free_dev(dev);
 203 }
 204
 205 void w1_remove_master_device(struct w1_bus_master *bm)
 206 {
 207         struct w1_master *dev, *found = NULL;
 208
 209         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
 210                 if (!dev->initialized)
 211                         continue;
 212
 213                 if (dev->bus_master->data == bm->data) {
 214                         found = dev;
 215                         break;
 216                 }
 217         }
 218
 219         if (!found) {
 220                 printk(KERN_ERR "Device doesn't exist.\n");
 221                 return;
 222         }
 223
 224         __w1_remove_master_device(found);
 225 }
 226
 227 EXPORT_SYMBOL(w1_add_master_device);
 228 EXPORT_SYMBOL(w1_remove_master_device);