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.h"
  25 #include "w1_log.h"
  26 #include "w1_netlink.h"
  27 #include "w1_int.h"
  28
  29 static int w1_search_count = -1; /* Default is continual scan */
  30 module_param_named(search_count, w1_search_count, int, 0);
  31
  32 static int w1_enable_pullup = 1;
  33 module_param_named(enable_pullup, w1_enable_pullup, int, 0);
  34
  35 static struct w1_master *w1_alloc_dev(u32 id, int slave_count, int slave_ttl,
  36                                        struct device_driver *driver,
  37                                        struct device *device)
  38 {
  39         struct w1_master *dev;
  40         int err;
  41
  42         /*
  43          * We are in process context(kernel thread), so can sleep.
  44          */
  45         dev = kzalloc(sizeof(struct w1_master) + sizeof(struct w1_bus_master), GFP_KERNEL);
  46         if (!dev) {
  47                 pr_err("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       = w1_search_count;
  63         dev->enable_pullup      = w1_enable_pullup;
  64
  65         /* 1 for w1_process to decrement
  66          * 1 for __w1_remove_master_device to decrement
  67          */
  68         atomic_set(&dev->refcnt, 2);
  69
  70         INIT_LIST_HEAD(&dev->slist);
  71         INIT_LIST_HEAD(&dev->async_list);
  72         mutex_init(&dev->mutex);
  73         mutex_init(&dev->bus_mutex);
  74         mutex_init(&dev->list_mutex);
  75
  76         memcpy(&dev->dev, device, sizeof(struct device));
  77         dev_set_name(&dev->dev, "w1_bus_master%u", dev->id);
  78         snprintf(dev->name, sizeof(dev->name), "w1_bus_master%u", dev->id);
  79         dev->dev.init_name = dev->name;
  80
  81         dev->driver = driver;
  82
  83         dev->seq = 1;
  84
  85         err = device_register(&dev->dev);
  86         if (err) {
  87                 pr_err("Failed to register master device. err=%d\n", err);
  88                 put_device(&dev->dev);
  89                 dev = NULL;
  90         }
  91
  92         return dev;
  93 }
  94
  95 static void w1_free_dev(struct w1_master *dev)
  96 {
  97         device_unregister(&dev->dev);
  98 }
  99
 100 /**
 101  * w1_add_master_device() - registers a new master device
 102  * @master:     master bus device to register
 103  */
 104 int w1_add_master_device(struct w1_bus_master *master)
 105 {
 106         struct w1_master *dev, *entry;
 107         int retval = 0;
 108         struct w1_netlink_msg msg;
 109         int id, found;
 110
 111         /* validate minimum functionality */
 112         if (!(master->touch_bit && master->reset_bus) &&
 113             !(master->write_bit && master->read_bit) &&
 114             !(master->write_byte && master->read_byte && master->reset_bus)) {
 115                 pr_err("w1_add_master_device: invalid function set\n");
 116                 return(-EINVAL);
 117         }
 118
 119         /* Lock until the device is added (or not) to w1_masters. */
 120         mutex_lock(&w1_mlock);
 121         /* Search for the first available id (starting at 1). */
 122         id = 0;
 123         do {
 124                 ++id;
 125                 found = 0;
 126                 list_for_each_entry(entry, &w1_masters, w1_master_entry) {
 127                         if (entry->id == id) {
 128                                 found = 1;
 129                                 break;
 130                         }
 131                 }
 132         } while (found);
 133
 134         dev = w1_alloc_dev(id, w1_max_slave_count, w1_max_slave_ttl,
 135                 &w1_master_driver, &w1_master_device);
 136         if (!dev) {
 137                 mutex_unlock(&w1_mlock);
 138                 return -ENOMEM;
 139         }
 140
 141         retval =  w1_create_master_attributes(dev);
 142         if (retval) {
 143                 mutex_unlock(&w1_mlock);
 144                 goto err_out_free_dev;
 145         }
 146
 147         memcpy(dev->bus_master, master, sizeof(struct w1_bus_master));
 148
 149         dev->initialized = 1;
 150
 151         dev->thread = kthread_run(&w1_process, dev, "%s", dev->name);
 152         if (IS_ERR(dev->thread)) {
 153                 retval = PTR_ERR(dev->thread);
 154                 dev_err(&dev->dev,
 155                          "Failed to create new kernel thread. err=%d\n",
 156                          retval);
 157                 mutex_unlock(&w1_mlock);
 158                 goto err_out_rm_attr;
 159         }
 160
 161         list_add(&dev->w1_master_entry, &w1_masters);
 162         mutex_unlock(&w1_mlock);
 163
 164         memset(&msg, 0, sizeof(msg));
 165         msg.id.mst.id = dev->id;
 166         msg.type = W1_MASTER_ADD;
 167         w1_netlink_send(dev, &msg);
 168
 169         return 0;
 170
 171 #if 0 /* Thread cleanup code, not required currently. */
 172 err_out_kill_thread:
 173         set_bit(W1_ABORT_SEARCH, &dev->flags);
 174         kthread_stop(dev->thread);
 175 #endif
 176 err_out_rm_attr:
 177         w1_destroy_master_attributes(dev);
 178 err_out_free_dev:
 179         w1_free_dev(dev);
 180
 181         return retval;
 182 }
 183
 184 void __w1_remove_master_device(struct w1_master *dev)
 185 {
 186         struct w1_netlink_msg msg;
 187         struct w1_slave *sl, *sln;
 188
 189         mutex_lock(&w1_mlock);
 190         list_del(&dev->w1_master_entry);
 191         mutex_unlock(&w1_mlock);
 192
 193         set_bit(W1_ABORT_SEARCH, &dev->flags);
 194         kthread_stop(dev->thread);
 195
 196         mutex_lock(&dev->mutex);
 197         mutex_lock(&dev->list_mutex);
 198         list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
 199                 mutex_unlock(&dev->list_mutex);
 200                 w1_slave_detach(sl);
 201                 mutex_lock(&dev->list_mutex);
 202         }
 203         w1_destroy_master_attributes(dev);
 204         mutex_unlock(&dev->list_mutex);
 205         mutex_unlock(&dev->mutex);
 206         atomic_dec(&dev->refcnt);
 207
 208         while (atomic_read(&dev->refcnt)) {
 209                 dev_info(&dev->dev, "Waiting for %s to become free: refcnt=%d.\n",
 210                                 dev->name, atomic_read(&dev->refcnt));
 211
 212                 if (msleep_interruptible(1000))
 213                         flush_signals(current);
 214                 mutex_lock(&dev->list_mutex);
 215                 w1_process_callbacks(dev);
 216                 mutex_unlock(&dev->list_mutex);
 217         }
 218         mutex_lock(&dev->list_mutex);
 219         w1_process_callbacks(dev);
 220         mutex_unlock(&dev->list_mutex);
 221
 222         memset(&msg, 0, sizeof(msg));
 223         msg.id.mst.id = dev->id;
 224         msg.type = W1_MASTER_REMOVE;
 225         w1_netlink_send(dev, &msg);
 226
 227         w1_free_dev(dev);
 228 }
 229
 230 /**
 231  * w1_remove_master_device() - unregister a master device
 232  * @bm: master bus device to remove
 233  */
 234 void w1_remove_master_device(struct w1_bus_master *bm)
 235 {
 236         struct w1_master *dev, *found = NULL;
 237
 238         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
 239                 if (!dev->initialized)
 240                         continue;
 241
 242                 if (dev->bus_master->data == bm->data) {
 243                         found = dev;
 244                         break;
 245                 }
 246         }
 247
 248         if (!found) {
 249                 pr_err("Device doesn't exist.\n");
 250                 return;
 251         }
 252
 253         __w1_remove_master_device(found);
 254 }
 255
 256 EXPORT_SYMBOL(w1_add_master_device);
 257 EXPORT_SYMBOL(w1_remove_master_device);