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_netlink.h"
  26 #include "w1_int.h"
  27
  28 static int w1_search_count = -1; /* Default is continual scan */
  29 module_param_named(search_count, w1_search_count, int, 0);
  30
  31 static int w1_enable_pullup = 1;
  32 module_param_named(enable_pullup, w1_enable_pullup, int, 0);
  33
  34 static struct w1_master *w1_alloc_dev(u32 id, int slave_count, int slave_ttl,
  35                                        struct device_driver *driver,
  36                                        struct device *device)
  37 {
  38         struct w1_master *dev;
  39         int err;
  40
  41         /*
  42          * We are in process context(kernel thread), so can sleep.
  43          */
  44         dev = kzalloc(sizeof(struct w1_master) + sizeof(struct w1_bus_master), GFP_KERNEL);
  45         if (!dev) {
  46                 pr_err("Failed to allocate %zd bytes for new w1 device.\n",
  47                         sizeof(struct w1_master));
  48                 return NULL;
  49         }
  50
  51
  52         dev->bus_master = (struct w1_bus_master *)(dev + 1);
  53
  54         dev->owner              = THIS_MODULE;
  55         dev->max_slave_count    = slave_count;
  56         dev->slave_count        = 0;
  57         dev->attempts           = 0;
  58         dev->initialized        = 0;
  59         dev->id                 = id;
  60         dev->slave_ttl          = slave_ttl;
  61         dev->search_count       = w1_search_count;
  62         dev->enable_pullup      = w1_enable_pullup;
  63
  64         /* 1 for w1_process to decrement
  65          * 1 for __w1_remove_master_device to decrement
  66          */
  67         atomic_set(&dev->refcnt, 2);
  68
  69         INIT_LIST_HEAD(&dev->slist);
  70         INIT_LIST_HEAD(&dev->async_list);
  71         mutex_init(&dev->mutex);
  72         mutex_init(&dev->bus_mutex);
  73         mutex_init(&dev->list_mutex);
  74
  75         memcpy(&dev->dev, device, sizeof(struct device));
  76         dev_set_name(&dev->dev, "w1_bus_master%u", dev->id);
  77         snprintf(dev->name, sizeof(dev->name), "w1_bus_master%u", dev->id);
  78         dev->dev.init_name = dev->name;
  79
  80         dev->driver = driver;
  81
  82         dev->seq = 1;
  83
  84         err = device_register(&dev->dev);
  85         if (err) {
  86                 pr_err("Failed to register master device. err=%d\n", err);
  87                 put_device(&dev->dev);
  88                 dev = NULL;
  89         }
  90
  91         return dev;
  92 }
  93
  94 static void w1_free_dev(struct w1_master *dev)
  95 {
  96         device_unregister(&dev->dev);
  97 }
  98
  99 /**
 100  * w1_add_master_device() - registers a new master device
 101  * @master:     master bus device to register
 102  */
 103 int w1_add_master_device(struct w1_bus_master *master)
 104 {
 105         struct w1_master *dev, *entry;
 106         int retval = 0;
 107         struct w1_netlink_msg msg;
 108         int id, found;
 109
 110         /* validate minimum functionality */
 111         if (!(master->touch_bit && master->reset_bus) &&
 112             !(master->write_bit && master->read_bit) &&
 113             !(master->write_byte && master->read_byte && master->reset_bus)) {
 114                 pr_err("w1_add_master_device: invalid function set\n");
 115                 return(-EINVAL);
 116         }
 117
 118         /* Lock until the device is added (or not) to w1_masters. */
 119         mutex_lock(&w1_mlock);
 120         /* Search for the first available id (starting at 1). */
 121         id = 0;
 122         do {
 123                 ++id;
 124                 found = 0;
 125                 list_for_each_entry(entry, &w1_masters, w1_master_entry) {
 126                         if (entry->id == id) {
 127                                 found = 1;
 128                                 break;
 129                         }
 130                 }
 131         } while (found);
 132
 133         dev = w1_alloc_dev(id, w1_max_slave_count, w1_max_slave_ttl,
 134                 &w1_master_driver, &w1_master_device);
 135         if (!dev) {
 136                 mutex_unlock(&w1_mlock);
 137                 return -ENOMEM;
 138         }
 139
 140         retval =  w1_create_master_attributes(dev);
 141         if (retval) {
 142                 mutex_unlock(&w1_mlock);
 143                 goto err_out_free_dev;
 144         }
 145
 146         memcpy(dev->bus_master, master, sizeof(struct w1_bus_master));
 147
 148         dev->initialized = 1;
 149
 150         dev->thread = kthread_run(&w1_process, dev, "%s", dev->name);
 151         if (IS_ERR(dev->thread)) {
 152                 retval = PTR_ERR(dev->thread);
 153                 dev_err(&dev->dev,
 154                          "Failed to create new kernel thread. err=%d\n",
 155                          retval);
 156                 mutex_unlock(&w1_mlock);
 157                 goto err_out_rm_attr;
 158         }
 159
 160         list_add(&dev->w1_master_entry, &w1_masters);
 161         mutex_unlock(&w1_mlock);
 162
 163         memset(&msg, 0, sizeof(msg));
 164         msg.id.mst.id = dev->id;
 165         msg.type = W1_MASTER_ADD;
 166         w1_netlink_send(dev, &msg);
 167
 168         return 0;
 169
 170 #if 0 /* Thread cleanup code, not required currently. */
 171 err_out_kill_thread:
 172         set_bit(W1_ABORT_SEARCH, &dev->flags);
 173         kthread_stop(dev->thread);
 174 #endif
 175 err_out_rm_attr:
 176         w1_destroy_master_attributes(dev);
 177 err_out_free_dev:
 178         w1_free_dev(dev);
 179
 180         return retval;
 181 }
 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
 255 EXPORT_SYMBOL(w1_add_master_device);
 256 EXPORT_SYMBOL(w1_remove_master_device);