linux/drivers/w1/w1_int.c
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   1/*
   2 *      w1_int.c
   3 *
   4 * Copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net>
   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#include <linux/slab.h>
  27#include <linux/export.h>
  28#include <linux/moduleparam.h>
  29
  30#include "w1.h"
  31#include "w1_log.h"
  32#include "w1_netlink.h"
  33#include "w1_int.h"
  34
  35static int w1_search_count = -1; /* Default is continual scan */
  36module_param_named(search_count, w1_search_count, int, 0);
  37
  38static int w1_enable_pullup = 1;
  39module_param_named(enable_pullup, w1_enable_pullup, int, 0);
  40
  41static struct w1_master * w1_alloc_dev(u32 id, int slave_count, int slave_ttl,
  42                                       struct device_driver *driver,
  43                                       struct device *device)
  44{
  45        struct w1_master *dev;
  46        int err;
  47
  48        /*
  49         * We are in process context(kernel thread), so can sleep.
  50         */
  51        dev = kzalloc(sizeof(struct w1_master) + sizeof(struct w1_bus_master), GFP_KERNEL);
  52        if (!dev) {
  53                printk(KERN_ERR
  54                        "Failed to allocate %zd bytes for new w1 device.\n",
  55                        sizeof(struct w1_master));
  56                return NULL;
  57        }
  58
  59
  60        dev->bus_master = (struct w1_bus_master *)(dev + 1);
  61
  62        dev->owner              = THIS_MODULE;
  63        dev->max_slave_count    = slave_count;
  64        dev->slave_count        = 0;
  65        dev->attempts           = 0;
  66        dev->initialized        = 0;
  67        dev->id                 = id;
  68        dev->slave_ttl          = slave_ttl;
  69        dev->search_count       = w1_search_count;
  70        dev->enable_pullup      = w1_enable_pullup;
  71
  72        /* 1 for w1_process to decrement
  73         * 1 for __w1_remove_master_device to decrement
  74         */
  75        atomic_set(&dev->refcnt, 2);
  76
  77        INIT_LIST_HEAD(&dev->slist);
  78        mutex_init(&dev->mutex);
  79        mutex_init(&dev->bus_mutex);
  80
  81        memcpy(&dev->dev, device, sizeof(struct device));
  82        dev_set_name(&dev->dev, "w1_bus_master%u", dev->id);
  83        snprintf(dev->name, sizeof(dev->name), "w1_bus_master%u", dev->id);
  84        dev->dev.init_name = dev->name;
  85
  86        dev->driver = driver;
  87
  88        dev->seq = 1;
  89
  90        err = device_register(&dev->dev);
  91        if (err) {
  92                printk(KERN_ERR "Failed to register master device. err=%d\n", err);
  93                memset(dev, 0, sizeof(struct w1_master));
  94                kfree(dev);
  95                dev = NULL;
  96        }
  97
  98        return dev;
  99}
 100
 101static void w1_free_dev(struct w1_master *dev)
 102{
 103        device_unregister(&dev->dev);
 104}
 105
 106int w1_add_master_device(struct w1_bus_master *master)
 107{
 108        struct w1_master *dev, *entry;
 109        int retval = 0;
 110        struct w1_netlink_msg msg;
 111        int id, found;
 112
 113        /* validate minimum functionality */
 114        if (!(master->touch_bit && master->reset_bus) &&
 115            !(master->write_bit && master->read_bit) &&
 116            !(master->write_byte && master->read_byte && master->reset_bus)) {
 117                printk(KERN_ERR "w1_add_master_device: invalid function set\n");
 118                return(-EINVAL);
 119        }
 120        /* While it would be electrically possible to make a device that
 121         * generated a strong pullup in bit bang mode, only hardware that
 122         * controls 1-wire time frames are even expected to support a strong
 123         * pullup.  w1_io.c would need to support calling set_pullup before
 124         * the last write_bit operation of a w1_write_8 which it currently
 125         * doesn't.
 126         */
 127        if (!master->write_byte && !master->touch_bit && master->set_pullup) {
 128                printk(KERN_ERR "w1_add_master_device: set_pullup requires "
 129                        "write_byte or touch_bit, disabling\n");
 130                master->set_pullup = NULL;
 131        }
 132
 133        /* Lock until the device is added (or not) to w1_masters. */
 134        mutex_lock(&w1_mlock);
 135        /* Search for the first available id (starting at 1). */
 136        id = 0;
 137        do {
 138                ++id;
 139                found = 0;
 140                list_for_each_entry(entry, &w1_masters, w1_master_entry) {
 141                        if (entry->id == id) {
 142                                found = 1;
 143                                break;
 144                        }
 145                }
 146        } while (found);
 147
 148        dev = w1_alloc_dev(id, w1_max_slave_count, w1_max_slave_ttl,
 149                &w1_master_driver, &w1_master_device);
 150        if (!dev) {
 151                mutex_unlock(&w1_mlock);
 152                return -ENOMEM;
 153        }
 154
 155        retval =  w1_create_master_attributes(dev);
 156        if (retval) {
 157                mutex_unlock(&w1_mlock);
 158                goto err_out_free_dev;
 159        }
 160
 161        memcpy(dev->bus_master, master, sizeof(struct w1_bus_master));
 162
 163        dev->initialized = 1;
 164
 165        dev->thread = kthread_run(&w1_process, dev, "%s", dev->name);
 166        if (IS_ERR(dev->thread)) {
 167                retval = PTR_ERR(dev->thread);
 168                dev_err(&dev->dev,
 169                         "Failed to create new kernel thread. err=%d\n",
 170                         retval);
 171                mutex_unlock(&w1_mlock);
 172                goto err_out_rm_attr;
 173        }
 174
 175        list_add(&dev->w1_master_entry, &w1_masters);
 176        mutex_unlock(&w1_mlock);
 177
 178        memset(&msg, 0, sizeof(msg));
 179        msg.id.mst.id = dev->id;
 180        msg.type = W1_MASTER_ADD;
 181        w1_netlink_send(dev, &msg);
 182
 183        return 0;
 184
 185#if 0 /* Thread cleanup code, not required currently. */
 186err_out_kill_thread:
 187        kthread_stop(dev->thread);
 188#endif
 189err_out_rm_attr:
 190        w1_destroy_master_attributes(dev);
 191err_out_free_dev:
 192        w1_free_dev(dev);
 193
 194        return retval;
 195}
 196
 197void __w1_remove_master_device(struct w1_master *dev)
 198{
 199        struct w1_netlink_msg msg;
 200        struct w1_slave *sl, *sln;
 201
 202        kthread_stop(dev->thread);
 203
 204        mutex_lock(&w1_mlock);
 205        list_del(&dev->w1_master_entry);
 206        mutex_unlock(&w1_mlock);
 207
 208        mutex_lock(&dev->mutex);
 209        list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry)
 210                w1_slave_detach(sl);
 211        w1_destroy_master_attributes(dev);
 212        mutex_unlock(&dev->mutex);
 213        atomic_dec(&dev->refcnt);
 214
 215        while (atomic_read(&dev->refcnt)) {
 216                dev_info(&dev->dev, "Waiting for %s to become free: refcnt=%d.\n",
 217                                dev->name, atomic_read(&dev->refcnt));
 218
 219                if (msleep_interruptible(1000))
 220                        flush_signals(current);
 221        }
 222
 223        memset(&msg, 0, sizeof(msg));
 224        msg.id.mst.id = dev->id;
 225        msg.type = W1_MASTER_REMOVE;
 226        w1_netlink_send(dev, &msg);
 227
 228        w1_free_dev(dev);
 229}
 230
 231void w1_remove_master_device(struct w1_bus_master *bm)
 232{
 233        struct w1_master *dev, *found = NULL;
 234
 235        list_for_each_entry(dev, &w1_masters, w1_master_entry) {
 236                if (!dev->initialized)
 237                        continue;
 238
 239                if (dev->bus_master->data == bm->data) {
 240                        found = dev;
 241                        break;
 242                }
 243        }
 244
 245        if (!found) {
 246                printk(KERN_ERR "Device doesn't exist.\n");
 247                return;
 248        }
 249
 250        __w1_remove_master_device(found);
 251}
 252
 253EXPORT_SYMBOL(w1_add_master_device);
 254EXPORT_SYMBOL(w1_remove_master_device);
 255
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