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         /* 1 for w1_process to decrement
  64          * 1 for __w1_remove_master_device to decrement
  65          */
  66         atomic_set(&dev->refcnt, 2);
  67
  68         INIT_LIST_HEAD(&dev->slist);
  69         INIT_LIST_HEAD(&dev->async_list);
  70         mutex_init(&dev->mutex);
  71         mutex_init(&dev->bus_mutex);
  72         mutex_init(&dev->list_mutex);
  73
  74         memcpy(&dev->dev, device, sizeof(struct device));
  75         dev_set_name(&dev->dev, "w1_bus_master%u", dev->id);
  76         snprintf(dev->name, sizeof(dev->name), "w1_bus_master%u", dev->id);
  77         dev->dev.init_name = dev->name;
  78
  79         dev->driver = driver;
  80
  81         dev->seq = 1;
  82
  83         err = device_register(&dev->dev);
  84         if (err) {
  85                 pr_err("Failed to register master device. err=%d\n", err);
  86                 put_device(&dev->dev);
  87                 dev = NULL;
  88         }
  89
  90         return dev;
  91 }
  92
  93 static void w1_free_dev(struct w1_master *dev)
  94 {
  95         device_unregister(&dev->dev);
  96 }
  97
  98 /**
  99  * w1_add_master_device() - registers a new master device
 100  * @master:     master bus device to register
 101  */
 102 int w1_add_master_device(struct w1_bus_master *master)
 103 {
 104         struct w1_master *dev, *entry;
 105         int retval = 0;
 106         struct w1_netlink_msg msg;
 107         int id, found;
 108
 109         /* validate minimum functionality */
 110         if (!(master->touch_bit && master->reset_bus) &&
 111             !(master->write_bit && master->read_bit) &&
 112             !(master->write_byte && master->read_byte && master->reset_bus)) {
 113                 pr_err("w1_add_master_device: invalid function set\n");
 114                 return(-EINVAL);
 115         }
 116
 117         /* Lock until the device is added (or not) to w1_masters. */
 118         mutex_lock(&w1_mlock);
 119         /* Search for the first available id (starting at 1). */
 120         id = 0;
 121         do {
 122                 ++id;
 123                 found = 0;
 124                 list_for_each_entry(entry, &w1_masters, w1_master_entry) {
 125                         if (entry->id == id) {
 126                                 found = 1;
 127                                 break;
 128                         }
 129                 }
 130         } while (found);
 131
 132         dev = w1_alloc_dev(id, w1_max_slave_count, w1_max_slave_ttl,
 133                 &w1_master_driver, &w1_master_device);
 134         if (!dev) {
 135                 mutex_unlock(&w1_mlock);
 136                 return -ENOMEM;
 137         }
 138
 139         retval =  w1_create_master_attributes(dev);
 140         if (retval) {
 141                 mutex_unlock(&w1_mlock);
 142                 goto err_out_free_dev;
 143         }
 144
 145         memcpy(dev->bus_master, master, sizeof(struct w1_bus_master));
 146
 147         dev->initialized = 1;
 148
 149         dev->thread = kthread_run(&w1_process, dev, "%s", dev->name);
 150         if (IS_ERR(dev->thread)) {
 151                 retval = PTR_ERR(dev->thread);
 152                 dev_err(&dev->dev,
 153                          "Failed to create new kernel thread. err=%d\n",
 154                          retval);
 155                 mutex_unlock(&w1_mlock);
 156                 goto err_out_rm_attr;
 157         }
 158
 159         list_add(&dev->w1_master_entry, &w1_masters);
 160         mutex_unlock(&w1_mlock);
 161
 162         memset(&msg, 0, sizeof(msg));
 163         msg.id.mst.id = dev->id;
 164         msg.type = W1_MASTER_ADD;
 165         w1_netlink_send(dev, &msg);
 166
 167         return 0;
 168
 169 #if 0 /* Thread cleanup code, not required currently. */
 170 err_out_kill_thread:
 171         set_bit(W1_ABORT_SEARCH, &dev->flags);
 172         kthread_stop(dev->thread);
 173 #endif
 174 err_out_rm_attr:
 175         w1_destroy_master_attributes(dev);
 176 err_out_free_dev:
 177         w1_free_dev(dev);
 178
 179         return retval;
 180 }
 181 EXPORT_SYMBOL(w1_add_master_device);
 182
 183 void __w1_remove_master_device(struct w1_master *dev)
 184 {
 185         struct w1_netlink_msg msg;
 186         struct w1_slave *sl, *sln;
 187
 188         mutex_lock(&w1_mlock);
 189         list_del(&dev->w1_master_entry);
 190         mutex_unlock(&w1_mlock);
 191
 192         set_bit(W1_ABORT_SEARCH, &dev->flags);
 193         kthread_stop(dev->thread);
 194
 195         mutex_lock(&dev->mutex);
 196         mutex_lock(&dev->list_mutex);
 197         list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
 198                 mutex_unlock(&dev->list_mutex);
 199                 w1_slave_detach(sl);
 200                 mutex_lock(&dev->list_mutex);
 201         }
 202         w1_destroy_master_attributes(dev);
 203         mutex_unlock(&dev->list_mutex);
 204         mutex_unlock(&dev->mutex);
 205         atomic_dec(&dev->refcnt);
 206
 207         while (atomic_read(&dev->refcnt)) {
 208                 dev_info(&dev->dev, "Waiting for %s to become free: refcnt=%d.\n",
 209                                 dev->name, atomic_read(&dev->refcnt));
 210
 211                 if (msleep_interruptible(1000))
 212                         flush_signals(current);
 213                 mutex_lock(&dev->list_mutex);
 214                 w1_process_callbacks(dev);
 215                 mutex_unlock(&dev->list_mutex);
 216         }
 217         mutex_lock(&dev->list_mutex);
 218         w1_process_callbacks(dev);
 219         mutex_unlock(&dev->list_mutex);
 220
 221         memset(&msg, 0, sizeof(msg));
 222         msg.id.mst.id = dev->id;
 223         msg.type = W1_MASTER_REMOVE;
 224         w1_netlink_send(dev, &msg);
 225
 226         w1_free_dev(dev);
 227 }
 228
 229 /**
 230  * w1_remove_master_device() - unregister a master device
 231  * @bm: master bus device to remove
 232  */
 233 void w1_remove_master_device(struct w1_bus_master *bm)
 234 {
 235         struct w1_master *dev, *found = NULL;
 236
 237         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
 238                 if (!dev->initialized)
 239                         continue;
 240
 241                 if (dev->bus_master->data == bm->data) {
 242                         found = dev;
 243                         break;
 244                 }
 245         }
 246
 247         if (!found) {
 248                 pr_err("Device doesn't exist.\n");
 249                 return;
 250         }
 251
 252         __w1_remove_master_device(found);
 253 }
 254 EXPORT_SYMBOL(w1_remove_master_device);