drivers/w1/w1_int.c

   1 /*
   2  * Copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  */
  14
  15 #include <linux/kernel.h>
  16 #include <linux/list.h>
  17 #include <linux/delay.h>
  18 #include <linux/kthread.h>
  19 #include <linux/slab.h>
  20 #include <linux/sched/signal.h>
  21 #include <linux/export.h>
  22 #include <linux/moduleparam.h>
  23
  24 #include "w1_internal.h"
  25 #include "w1_netlink.h"
  26
  27 static int w1_search_count = -1; /* Default is continual scan */
  28 module_param_named(search_count, w1_search_count, int, 0);
  29
  30 static int w1_enable_pullup = 1;
  31 module_param_named(enable_pullup, w1_enable_pullup, int, 0);
  32
  33 static struct w1_master *w1_alloc_dev(u32 id, int slave_count, int slave_ttl,
  34                                        struct device_driver *driver,
  35                                        struct device *device)
  36 {
  37         struct w1_master *dev;
  38         int err;
  39
  40         /*
  41          * We are in process context(kernel thread), so can sleep.
  42          */
  43         dev = kzalloc(sizeof(struct w1_master) + sizeof(struct w1_bus_master), GFP_KERNEL);
  44         if (!dev) {
  45                 pr_err("Failed to allocate %zd bytes for new w1 device.\n",
  46                         sizeof(struct w1_master));
  47                 return NULL;
  48         }
  49
  50
  51         dev->bus_master = (struct w1_bus_master *)(dev + 1);
  52
  53         dev->owner              = THIS_MODULE;
  54         dev->max_slave_count    = slave_count;
  55         dev->slave_count        = 0;
  56         dev->attempts           = 0;
  57         dev->initialized        = 0;
  58         dev->id                 = id;
  59         dev->slave_ttl          = slave_ttl;
  60         dev->search_count       = w1_search_count;
  61         dev->enable_pullup      = w1_enable_pullup;
  62
  63         /* For __w1_remove_master_device to decrement
  64          */
  65         atomic_set(&dev->refcnt, 1);
  66
  67         INIT_LIST_HEAD(&dev->slist);
  68         INIT_LIST_HEAD(&dev->async_list);
  69         mutex_init(&dev->mutex);
  70         mutex_init(&dev->bus_mutex);
  71         mutex_init(&dev->list_mutex);
  72
  73         memcpy(&dev->dev, device, sizeof(struct device));
  74         dev_set_name(&dev->dev, "w1_bus_master%u", dev->id);
  75         snprintf(dev->name, sizeof(dev->name), "w1_bus_master%u", dev->id);
  76         dev->dev.init_name = dev->name;
  77
  78         dev->driver = driver;
  79
  80         dev->seq = 1;
  81
  82         err = device_register(&dev->dev);
  83         if (err) {
  84                 pr_err("Failed to register master device. err=%d\n", err);
  85                 put_device(&dev->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 /**
  98  * w1_add_master_device() - registers a new master device
  99  * @master:     master bus device to register
 100  */
 101 int w1_add_master_device(struct w1_bus_master *master)
 102 {
 103         struct w1_master *dev, *entry;
 104         int retval = 0;
 105         struct w1_netlink_msg msg;
 106         int id, found;
 107
 108         /* validate minimum functionality */
 109         if (!(master->touch_bit && master->reset_bus) &&
 110             !(master->write_bit && master->read_bit) &&
 111             !(master->write_byte && master->read_byte && master->reset_bus)) {
 112                 pr_err("w1_add_master_device: invalid function set\n");
 113                 return(-EINVAL);
 114         }
 115
 116         /* Lock until the device is added (or not) to w1_masters. */
 117         mutex_lock(&w1_mlock);
 118         /* Search for the first available id (starting at 1). */
 119         id = 0;
 120         do {
 121                 ++id;
 122                 found = 0;
 123                 list_for_each_entry(entry, &w1_masters, w1_master_entry) {
 124                         if (entry->id == id) {
 125                                 found = 1;
 126                                 break;
 127                         }
 128                 }
 129         } while (found);
 130
 131         dev = w1_alloc_dev(id, w1_max_slave_count, w1_max_slave_ttl,
 132                 &w1_master_driver, &w1_master_device);
 133         if (!dev) {
 134                 mutex_unlock(&w1_mlock);
 135                 return -ENOMEM;
 136         }
 137
 138         retval =  w1_create_master_attributes(dev);
 139         if (retval) {
 140                 mutex_unlock(&w1_mlock);
 141                 goto err_out_free_dev;
 142         }
 143
 144         memcpy(dev->bus_master, master, sizeof(struct w1_bus_master));
 145
 146         dev->initialized = 1;
 147
 148         dev->thread = kthread_run(&w1_process, dev, "%s", dev->name);
 149         if (IS_ERR(dev->thread)) {
 150                 retval = PTR_ERR(dev->thread);
 151                 dev_err(&dev->dev,
 152                          "Failed to create new kernel thread. err=%d\n",
 153                          retval);
 154                 mutex_unlock(&w1_mlock);
 155                 goto err_out_rm_attr;
 156         }
 157
 158         list_add(&dev->w1_master_entry, &w1_masters);
 159         mutex_unlock(&w1_mlock);
 160
 161         memset(&msg, 0, sizeof(msg));
 162         msg.id.mst.id = dev->id;
 163         msg.type = W1_MASTER_ADD;
 164         w1_netlink_send(dev, &msg);
 165
 166         return 0;
 167
 168 #if 0 /* Thread cleanup code, not required currently. */
 169 err_out_kill_thread:
 170         set_bit(W1_ABORT_SEARCH, &dev->flags);
 171         kthread_stop(dev->thread);
 172 #endif
 173 err_out_rm_attr:
 174         w1_destroy_master_attributes(dev);
 175 err_out_free_dev:
 176         w1_free_dev(dev);
 177
 178         return retval;
 179 }
 180 EXPORT_SYMBOL(w1_add_master_device);
 181
 182 void __w1_remove_master_device(struct w1_master *dev)
 183 {
 184         struct w1_netlink_msg msg;
 185         struct w1_slave *sl, *sln;
 186
 187         mutex_lock(&w1_mlock);
 188         list_del(&dev->w1_master_entry);
 189         mutex_unlock(&w1_mlock);
 190
 191         set_bit(W1_ABORT_SEARCH, &dev->flags);
 192         kthread_stop(dev->thread);
 193
 194         mutex_lock(&dev->mutex);
 195         mutex_lock(&dev->list_mutex);
 196         list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
 197                 mutex_unlock(&dev->list_mutex);
 198                 w1_slave_detach(sl);
 199                 mutex_lock(&dev->list_mutex);
 200         }
 201         w1_destroy_master_attributes(dev);
 202         mutex_unlock(&dev->list_mutex);
 203         mutex_unlock(&dev->mutex);
 204         atomic_dec(&dev->refcnt);
 205
 206         while (atomic_read(&dev->refcnt)) {
 207                 dev_info(&dev->dev, "Waiting for %s to become free: refcnt=%d.\n",
 208                                 dev->name, atomic_read(&dev->refcnt));
 209
 210                 if (msleep_interruptible(1000))
 211                         flush_signals(current);
 212                 mutex_lock(&dev->list_mutex);
 213                 w1_process_callbacks(dev);
 214                 mutex_unlock(&dev->list_mutex);
 215         }
 216         mutex_lock(&dev->list_mutex);
 217         w1_process_callbacks(dev);
 218         mutex_unlock(&dev->list_mutex);
 219
 220         memset(&msg, 0, sizeof(msg));
 221         msg.id.mst.id = dev->id;
 222         msg.type = W1_MASTER_REMOVE;
 223         w1_netlink_send(dev, &msg);
 224
 225         w1_free_dev(dev);
 226 }
 227
 228 /**
 229  * w1_remove_master_device() - unregister a master device
 230  * @bm: master bus device to remove
 231  */
 232 void w1_remove_master_device(struct w1_bus_master *bm)
 233 {
 234         struct w1_master *dev, *found = NULL;
 235
 236         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
 237                 if (!dev->initialized)
 238                         continue;
 239
 240                 if (dev->bus_master->data == bm->data) {
 241                         found = dev;
 242                         break;
 243                 }
 244         }
 245
 246         if (!found) {
 247                 pr_err("Device doesn't exist.\n");
 248                 return;
 249         }
 250
 251         __w1_remove_master_device(found);
 252 }
 253 EXPORT_SYMBOL(w1_remove_master_device);