drivers/w1/w1_int.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net>
   4  */
   5
   6 #include <linux/kernel.h>
   7 #include <linux/list.h>
   8 #include <linux/delay.h>
   9 #include <linux/kthread.h>
  10 #include <linux/slab.h>
  11 #include <linux/sched/signal.h>
  12 #include <linux/export.h>
  13 #include <linux/moduleparam.h>
  14
  15 #include "w1_internal.h"
  16 #include "w1_netlink.h"
  17
  18 static int w1_search_count = -1; /* Default is continual scan */
  19 module_param_named(search_count, w1_search_count, int, 0);
  20
  21 static int w1_enable_pullup = 1;
  22 module_param_named(enable_pullup, w1_enable_pullup, int, 0);
  23
  24 static struct w1_master *w1_alloc_dev(u32 id, int slave_count, int slave_ttl,
  25                                        struct device_driver *driver,
  26                                        struct device *device)
  27 {
  28         struct w1_master *dev;
  29         int err;
  30
  31         /*
  32          * We are in process context(kernel thread), so can sleep.
  33          */
  34         dev = kzalloc(sizeof(struct w1_master) + sizeof(struct w1_bus_master), GFP_KERNEL);
  35         if (!dev) {
  36                 pr_err("Failed to allocate %zd bytes for new w1 device.\n",
  37                         sizeof(struct w1_master));
  38                 return NULL;
  39         }
  40
  41
  42         dev->bus_master = (struct w1_bus_master *)(dev + 1);
  43
  44         dev->owner              = THIS_MODULE;
  45         dev->max_slave_count    = slave_count;
  46         dev->slave_count        = 0;
  47         dev->attempts           = 0;
  48         dev->initialized        = 0;
  49         dev->id                 = id;
  50         dev->slave_ttl          = slave_ttl;
  51         dev->search_count       = w1_search_count;
  52         dev->enable_pullup      = w1_enable_pullup;
  53
  54         /* For __w1_remove_master_device to decrement
  55          */
  56         atomic_set(&dev->refcnt, 1);
  57
  58         INIT_LIST_HEAD(&dev->slist);
  59         INIT_LIST_HEAD(&dev->async_list);
  60         mutex_init(&dev->mutex);
  61         mutex_init(&dev->bus_mutex);
  62         mutex_init(&dev->list_mutex);
  63
  64         memcpy(&dev->dev, device, sizeof(struct device));
  65         dev_set_name(&dev->dev, "w1_bus_master%u", dev->id);
  66         snprintf(dev->name, sizeof(dev->name), "w1_bus_master%u", dev->id);
  67         dev->dev.init_name = dev->name;
  68
  69         dev->driver = driver;
  70
  71         dev->seq = 1;
  72
  73         err = device_register(&dev->dev);
  74         if (err) {
  75                 pr_err("Failed to register master device. err=%d\n", err);
  76                 put_device(&dev->dev);
  77                 dev = NULL;
  78         }
  79
  80         return dev;
  81 }
  82
  83 static void w1_free_dev(struct w1_master *dev)
  84 {
  85         device_unregister(&dev->dev);
  86 }
  87
  88 /**
  89  * w1_add_master_device() - registers a new master device
  90  * @master:     master bus device to register
  91  */
  92 int w1_add_master_device(struct w1_bus_master *master)
  93 {
  94         struct w1_master *dev, *entry;
  95         int retval = 0;
  96         struct w1_netlink_msg msg;
  97         int id, found;
  98
  99         /* validate minimum functionality */
 100         if (!(master->touch_bit && master->reset_bus) &&
 101             !(master->write_bit && master->read_bit) &&
 102             !(master->write_byte && master->read_byte && master->reset_bus)) {
 103                 pr_err("w1_add_master_device: invalid function set\n");
 104                 return(-EINVAL);
 105         }
 106
 107         /* Lock until the device is added (or not) to w1_masters. */
 108         mutex_lock(&w1_mlock);
 109         /* Search for the first available id (starting at 1). */
 110         id = 0;
 111         do {
 112                 ++id;
 113                 found = 0;
 114                 list_for_each_entry(entry, &w1_masters, w1_master_entry) {
 115                         if (entry->id == id) {
 116                                 found = 1;
 117                                 break;
 118                         }
 119                 }
 120         } while (found);
 121
 122         dev = w1_alloc_dev(id, w1_max_slave_count, w1_max_slave_ttl,
 123                 &w1_master_driver, &w1_master_device);
 124         if (!dev) {
 125                 mutex_unlock(&w1_mlock);
 126                 return -ENOMEM;
 127         }
 128
 129         retval =  w1_create_master_attributes(dev);
 130         if (retval) {
 131                 mutex_unlock(&w1_mlock);
 132                 goto err_out_free_dev;
 133         }
 134
 135         memcpy(dev->bus_master, master, sizeof(struct w1_bus_master));
 136
 137         dev->initialized = 1;
 138
 139         dev->thread = kthread_run(&w1_process, dev, "%s", dev->name);
 140         if (IS_ERR(dev->thread)) {
 141                 retval = PTR_ERR(dev->thread);
 142                 dev_err(&dev->dev,
 143                          "Failed to create new kernel thread. err=%d\n",
 144                          retval);
 145                 mutex_unlock(&w1_mlock);
 146                 goto err_out_rm_attr;
 147         }
 148
 149         list_add(&dev->w1_master_entry, &w1_masters);
 150         mutex_unlock(&w1_mlock);
 151
 152         memset(&msg, 0, sizeof(msg));
 153         msg.id.mst.id = dev->id;
 154         msg.type = W1_MASTER_ADD;
 155         w1_netlink_send(dev, &msg);
 156
 157         return 0;
 158
 159 #if 0 /* Thread cleanup code, not required currently. */
 160 err_out_kill_thread:
 161         set_bit(W1_ABORT_SEARCH, &dev->flags);
 162         kthread_stop(dev->thread);
 163 #endif
 164 err_out_rm_attr:
 165         w1_destroy_master_attributes(dev);
 166 err_out_free_dev:
 167         w1_free_dev(dev);
 168
 169         return retval;
 170 }
 171 EXPORT_SYMBOL(w1_add_master_device);
 172
 173 void __w1_remove_master_device(struct w1_master *dev)
 174 {
 175         struct w1_netlink_msg msg;
 176         struct w1_slave *sl, *sln;
 177
 178         mutex_lock(&w1_mlock);
 179         list_del(&dev->w1_master_entry);
 180         mutex_unlock(&w1_mlock);
 181
 182         set_bit(W1_ABORT_SEARCH, &dev->flags);
 183         kthread_stop(dev->thread);
 184
 185         mutex_lock(&dev->mutex);
 186         mutex_lock(&dev->list_mutex);
 187         list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
 188                 mutex_unlock(&dev->list_mutex);
 189                 w1_slave_detach(sl);
 190                 mutex_lock(&dev->list_mutex);
 191         }
 192         w1_destroy_master_attributes(dev);
 193         mutex_unlock(&dev->list_mutex);
 194         mutex_unlock(&dev->mutex);
 195         atomic_dec(&dev->refcnt);
 196
 197         while (atomic_read(&dev->refcnt)) {
 198                 dev_info(&dev->dev, "Waiting for %s to become free: refcnt=%d.\n",
 199                                 dev->name, atomic_read(&dev->refcnt));
 200
 201                 if (msleep_interruptible(1000))
 202                         flush_signals(current);
 203                 mutex_lock(&dev->list_mutex);
 204                 w1_process_callbacks(dev);
 205                 mutex_unlock(&dev->list_mutex);
 206         }
 207         mutex_lock(&dev->list_mutex);
 208         w1_process_callbacks(dev);
 209         mutex_unlock(&dev->list_mutex);
 210
 211         memset(&msg, 0, sizeof(msg));
 212         msg.id.mst.id = dev->id;
 213         msg.type = W1_MASTER_REMOVE;
 214         w1_netlink_send(dev, &msg);
 215
 216         w1_free_dev(dev);
 217 }
 218
 219 /**
 220  * w1_remove_master_device() - unregister a master device
 221  * @bm: master bus device to remove
 222  */
 223 void w1_remove_master_device(struct w1_bus_master *bm)
 224 {
 225         struct w1_master *dev, *found = NULL;
 226
 227         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
 228                 if (!dev->initialized)
 229                         continue;
 230
 231                 if (dev->bus_master->data == bm->data) {
 232                         found = dev;
 233                         break;
 234                 }
 235         }
 236
 237         if (!found) {
 238                 pr_err("Device doesn't exist.\n");
 239                 return;
 240         }
 241
 242         __w1_remove_master_device(found);
 243 }
 244 EXPORT_SYMBOL(w1_remove_master_device);