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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net>
*/
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/delay.h>
#include <linux/kthread.h>
#include <linux/slab.h>
#include <linux/sched/signal.h>
#include <linux/export.h>
#include <linux/moduleparam.h>
#include "w1_internal.h"
#include "w1_netlink.h"
static int w1_search_count = -1; /* Default is continual scan */
module_param_named(search_count, w1_search_count, int, 0);
static int w1_enable_pullup = 1;
module_param_named(enable_pullup, w1_enable_pullup, int, 0);
static struct w1_master *w1_alloc_dev(u32 id, int slave_count, int slave_ttl,
struct device_driver *driver,
struct device *device)
{
struct w1_master *dev;
int err;
/*
* We are in process context(kernel thread), so can sleep.
*/
dev = kzalloc(sizeof(struct w1_master) + sizeof(struct w1_bus_master), GFP_KERNEL);
if (!dev) {
pr_err("Failed to allocate %zd bytes for new w1 device.\n",
sizeof(struct w1_master));
return NULL;
}
dev->bus_master = (struct w1_bus_master *)(dev + 1);
dev->owner = THIS_MODULE;
dev->max_slave_count = slave_count;
dev->slave_count = 0;
dev->attempts = 0;
dev->initialized = 0;
dev->id = id;
dev->slave_ttl = slave_ttl;
dev->search_count = w1_search_count;
dev->enable_pullup = w1_enable_pullup;
/* For __w1_remove_master_device to decrement
*/
atomic_set(&dev->refcnt, 1);
INIT_LIST_HEAD(&dev->slist);
INIT_LIST_HEAD(&dev->async_list);
mutex_init(&dev->mutex);
mutex_init(&dev->bus_mutex);
mutex_init(&dev->list_mutex);
memcpy(&dev->dev, device, sizeof(struct device));
dev_set_name(&dev->dev, "w1_bus_master%u", dev->id);
snprintf(dev->name, sizeof(dev->name), "w1_bus_master%u", dev->id);
dev->dev.init_name = dev->name;
dev->driver = driver;
dev->seq = 1;
err = device_register(&dev->dev);
if (err) {
pr_err("Failed to register master device. err=%d\n", err);
put_device(&dev->dev);
dev = NULL;
}
return dev;
}
static void w1_free_dev(struct w1_master *dev)
{
device_unregister(&dev->dev);
}
/**
* w1_add_master_device() - registers a new master device
* @master: master bus device to register
*/
int w1_add_master_device(struct w1_bus_master *master)
{
struct w1_master *dev, *entry;
int retval = 0;
struct w1_netlink_msg msg;
int id, found;
/* validate minimum functionality */
if (!(master->touch_bit && master->reset_bus) &&
!(master->write_bit && master->read_bit) &&
!(master->write_byte && master->read_byte && master->reset_bus)) {
pr_err("w1_add_master_device: invalid function set\n");
return(-EINVAL);
}
/* Lock until the device is added (or not) to w1_masters. */
mutex_lock(&w1_mlock);
/* Search for the first available id (starting at 1). */
id = 0;
do {
++id;
found = 0;
list_for_each_entry(entry, &w1_masters, w1_master_entry) {
if (entry->id == id) {
found = 1;
break;
}
}
} while (found);
dev = w1_alloc_dev(id, w1_max_slave_count, w1_max_slave_ttl,
&w1_master_driver, &w1_master_device);
if (!dev) {
mutex_unlock(&w1_mlock);
return -ENOMEM;
}
retval = w1_create_master_attributes(dev);
if (retval) {
mutex_unlock(&w1_mlock);
goto err_out_free_dev;
}
memcpy(dev->bus_master, master, sizeof(struct w1_bus_master));
dev->initialized = 1;
dev->thread = kthread_run(&w1_process, dev, "%s", dev->name);
if (IS_ERR(dev->thread)) {
retval = PTR_ERR(dev->thread);
dev_err(&dev->dev,
"Failed to create new kernel thread. err=%d\n",
retval);
mutex_unlock(&w1_mlock);
goto err_out_rm_attr;
}
list_add(&dev->w1_master_entry, &w1_masters);
mutex_unlock(&w1_mlock);
memset(&msg, 0, sizeof(msg));
msg.id.mst.id = dev->id;
msg.type = W1_MASTER_ADD;
w1_netlink_send(dev, &msg);
return 0;
#if 0 /* Thread cleanup code, not required currently. */
err_out_kill_thread:
set_bit(W1_ABORT_SEARCH, &dev->flags);
kthread_stop(dev->thread);
#endif
err_out_rm_attr:
w1_destroy_master_attributes(dev);
err_out_free_dev:
w1_free_dev(dev);
return retval;
}
EXPORT_SYMBOL(w1_add_master_device);
void __w1_remove_master_device(struct w1_master *dev)
{
struct w1_netlink_msg msg;
struct w1_slave *sl, *sln;
mutex_lock(&w1_mlock);
list_del(&dev->w1_master_entry);
mutex_unlock(&w1_mlock);
set_bit(W1_ABORT_SEARCH, &dev->flags);
kthread_stop(dev->thread);
mutex_lock(&dev->mutex);
mutex_lock(&dev->list_mutex);
list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry) {
mutex_unlock(&dev->list_mutex);
w1_slave_detach(sl);
mutex_lock(&dev->list_mutex);
}
w1_destroy_master_attributes(dev);
mutex_unlock(&dev->list_mutex);
mutex_unlock(&dev->mutex);
atomic_dec(&dev->refcnt);
while (atomic_read(&dev->refcnt)) {
dev_info(&dev->dev, "Waiting for %s to become free: refcnt=%d.\n",
dev->name, atomic_read(&dev->refcnt));
if (msleep_interruptible(1000))
flush_signals(current);
mutex_lock(&dev->list_mutex);
w1_process_callbacks(dev);
mutex_unlock(&dev->list_mutex);
}
mutex_lock(&dev->list_mutex);
w1_process_callbacks(dev);
mutex_unlock(&dev->list_mutex);
memset(&msg, 0, sizeof(msg));
msg.id.mst.id = dev->id;
msg.type = W1_MASTER_REMOVE;
w1_netlink_send(dev, &msg);
w1_free_dev(dev);
}
/**
* w1_remove_master_device() - unregister a master device
* @bm: master bus device to remove
*/
void w1_remove_master_device(struct w1_bus_master *bm)
{
struct w1_master *dev, *found = NULL;
list_for_each_entry(dev, &w1_masters, w1_master_entry) {
if (!dev->initialized)
continue;
if (dev->bus_master->data == bm->data) {
found = dev;
break;
}
}
if (!found) {
pr_err("Device doesn't exist.\n");
return;
}
__w1_remove_master_device(found);
}
EXPORT_SYMBOL(w1_remove_master_device);
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