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         /* 1 for w1_process to decrement
  55          * 1 for __w1_remove_master_device to decrement
  56          */
  57         atomic_set(&dev->refcnt, 2);
  58
  59         INIT_LIST_HEAD(&dev->slist);
  60         INIT_LIST_HEAD(&dev->async_list);
  61         mutex_init(&dev->mutex);
  62         mutex_init(&dev->bus_mutex);
  63         mutex_init(&dev->list_mutex);
  64
  65         memcpy(&dev->dev, device, sizeof(struct device));
  66         dev_set_name(&dev->dev, "w1_bus_master%u", dev->id);
  67         snprintf(dev->name, sizeof(dev->name), "w1_bus_master%u", dev->id);
  68         dev->dev.init_name = dev->name;
  69
  70         dev->driver = driver;
  71
  72         dev->seq = 1;
  73
  74         err = device_register(&dev->dev);
  75         if (err) {
  76                 pr_err("Failed to register master device. err=%d\n", err);
  77                 put_device(&dev->dev);
  78                 dev = NULL;
  79         }
  80
  81         return dev;
  82 }
  83
  84 static void w1_free_dev(struct w1_master *dev)
  85 {
  86         device_unregister(&dev->dev);
  87 }
  88
  89 /**
  90  * w1_add_master_device() - registers a new master device
  91  * @master:     master bus device to register
  92  */
  93 int w1_add_master_device(struct w1_bus_master *master)
  94 {
  95         struct w1_master *dev, *entry;
  96         int retval = 0;
  97         struct w1_netlink_msg msg;
  98         int id, found;
  99
 100         /* validate minimum functionality */
 101         if (!(master->touch_bit && master->reset_bus) &&
 102             !(master->write_bit && master->read_bit) &&
 103             !(master->write_byte && master->read_byte && master->reset_bus)) {
 104                 pr_err("w1_add_master_device: invalid function set\n");
 105                 return(-EINVAL);
 106         }
 107
 108         /* Lock until the device is added (or not) to w1_masters. */
 109         mutex_lock(&w1_mlock);
 110         /* Search for the first available id (starting at 1). */
 111         id = 0;
 112         do {
 113                 ++id;
 114                 found = 0;
 115                 list_for_each_entry(entry, &w1_masters, w1_master_entry) {
 116                         if (entry->id == id) {
 117                                 found = 1;
 118                                 break;
 119                         }
 120                 }
 121         } while (found);
 122
 123         dev = w1_alloc_dev(id, w1_max_slave_count, w1_max_slave_ttl,
 124                 &w1_master_driver, &w1_master_device);
 125         if (!dev) {
 126                 mutex_unlock(&w1_mlock);
 127                 return -ENOMEM;
 128         }
 129
 130         retval =  w1_create_master_attributes(dev);
 131         if (retval) {
 132                 mutex_unlock(&w1_mlock);
 133                 goto err_out_free_dev;
 134         }
 135
 136         memcpy(dev->bus_master, master, sizeof(struct w1_bus_master));
 137
 138         dev->initialized = 1;
 139
 140         dev->thread = kthread_run(&w1_process, dev, "%s", dev->name);
 141         if (IS_ERR(dev->thread)) {
 142                 retval = PTR_ERR(dev->thread);
 143                 dev_err(&dev->dev,
 144                          "Failed to create new kernel thread. err=%d\n",
 145                          retval);
 146                 mutex_unlock(&w1_mlock);
 147                 goto err_out_rm_attr;
 148         }
 149
 150         list_add(&dev->w1_master_entry, &w1_masters);
 151         mutex_unlock(&w1_mlock);
 152
 153         memset(&msg, 0, sizeof(msg));
 154         msg.id.mst.id = dev->id;
 155         msg.type = W1_MASTER_ADD;
 156         w1_netlink_send(dev, &msg);
 157
 158         return 0;
 159
 160 #if 0 /* Thread cleanup code, not required currently. */
 161 err_out_kill_thread:
 162         set_bit(W1_ABORT_SEARCH, &dev->flags);
 163         kthread_stop(dev->thread);
 164 #endif
 165 err_out_rm_attr:
 166         w1_destroy_master_attributes(dev);
 167 err_out_free_dev:
 168         w1_free_dev(dev);
 169
 170         return retval;
 171 }
 172 EXPORT_SYMBOL(w1_add_master_device);
 173
 174 void __w1_remove_master_device(struct w1_master *dev)
 175 {
 176         struct w1_netlink_msg msg;
 177         struct w1_slave *sl, *sln;
 178
 179         mutex_lock(&w1_mlock);
 180         list_del(&dev->w1_master_entry);
 181         mutex_unlock(&w1_mlock);
 182
 183         set_bit(W1_ABORT_SEARCH, &dev->flags);
 184         kthread_stop(dev->thread);
 185
 186         mutex_lock(&dev->mutex);
 187         mutex_lock(&dev->list_mutex);
 188         list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
 189                 mutex_unlock(&dev->list_mutex);
 190                 w1_slave_detach(sl);
 191                 mutex_lock(&dev->list_mutex);
 192         }
 193         w1_destroy_master_attributes(dev);
 194         mutex_unlock(&dev->list_mutex);
 195         mutex_unlock(&dev->mutex);
 196         atomic_dec(&dev->refcnt);
 197
 198         while (atomic_read(&dev->refcnt)) {
 199                 dev_info(&dev->dev, "Waiting for %s to become free: refcnt=%d.\n",
 200                                 dev->name, atomic_read(&dev->refcnt));
 201
 202                 if (msleep_interruptible(1000))
 203                         flush_signals(current);
 204                 mutex_lock(&dev->list_mutex);
 205                 w1_process_callbacks(dev);
 206                 mutex_unlock(&dev->list_mutex);
 207         }
 208         mutex_lock(&dev->list_mutex);
 209         w1_process_callbacks(dev);
 210         mutex_unlock(&dev->list_mutex);
 211
 212         memset(&msg, 0, sizeof(msg));
 213         msg.id.mst.id = dev->id;
 214         msg.type = W1_MASTER_REMOVE;
 215         w1_netlink_send(dev, &msg);
 216
 217         w1_free_dev(dev);
 218 }
 219
 220 /**
 221  * w1_remove_master_device() - unregister a master device
 222  * @bm: master bus device to remove
 223  */
 224 void w1_remove_master_device(struct w1_bus_master *bm)
 225 {
 226         struct w1_master *dev, *found = NULL;
 227
 228         list_for_each_entry(dev, &w1_masters, w1_master_entry) {
 229                 if (!dev->initialized)
 230                         continue;
 231
 232                 if (dev->bus_master->data == bm->data) {
 233                         found = dev;
 234                         break;
 235                 }
 236         }
 237
 238         if (!found) {
 239                 pr_err("Device doesn't exist.\n");
 240                 return;
 241         }
 242
 243         __w1_remove_master_device(found);
 244 }
 245 EXPORT_SYMBOL(w1_remove_master_device);