w1_int.c

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/*
 *  w1_int.c
 *
 * Copyright (c) 2004 Evgeniy Polyakov <[email protected]>
 *
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/delay.h>
#include <linux/kthread.h>
#include <linux/slab.h>
#include <linux/export.h>
#include <linux/moduleparam.h>

#include "w1.h"
#include "w1_log.h"
#include "w1_netlink.h"
#include "w1_int.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) {
        printk(KERN_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;

    /* 1 for w1_process to decrement
     * 1 for __w1_remove_master_device to decrement
     */
    atomic_set(&dev->refcnt, 2);

    INIT_LIST_HEAD(&dev->slist);
    mutex_init(&dev->mutex);
    mutex_init(&dev->bus_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) {
        printk(KERN_ERR "Failed to register master device. err=%d\n", err);
        memset(dev, 0, sizeof(struct w1_master));
        kfree(dev);
        dev = NULL;
    }

    return dev;
}

static void w1_free_dev(struct w1_master *dev)
{
    device_unregister(&dev->dev);
}

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)) {
        printk(KERN_ERR "w1_add_master_device: invalid function set\n");
        return(-EINVAL);
        }
    /* While it would be electrically possible to make a device that
     * generated a strong pullup in bit bang mode, only hardware that
     * controls 1-wire time frames are even expected to support a strong
     * pullup.  w1_io.c would need to support calling set_pullup before
     * the last write_bit operation of a w1_write_8 which it currently
     * doesn't.
     */
    if (!master->write_byte && !master->touch_bit && master->set_pullup) {
        printk(KERN_ERR "w1_add_master_device: set_pullup requires "
            "write_byte or touch_bit, disabling\n");
        master->set_pullup = NULL;
    }

    /* 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:
    kthread_stop(dev->thread);
#endif
err_out_rm_attr:
    w1_destroy_master_attributes(dev);
err_out_free_dev:
    w1_free_dev(dev);

    return retval;
}

void __w1_remove_master_device(struct w1_master *dev)
{
    struct w1_netlink_msg msg;
    struct w1_slave *sl, *sln;

    kthread_stop(dev->thread);

    mutex_lock(&w1_mlock);
    list_del(&dev->w1_master_entry);
    mutex_unlock(&w1_mlock);

    mutex_lock(&dev->mutex);
    list_for_each_entry_safe(sl, sln, &dev->slist, w1_slave_entry)
        w1_slave_detach(sl);
    w1_destroy_master_attributes(dev);
    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);
    }

    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);
}

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) {
        printk(KERN_ERR "Device doesn't exist.\n");
        return;
    }

    __w1_remove_master_device(found);
}

EXPORT_SYMBOL(w1_add_master_device);
EXPORT_SYMBOL(w1_remove_master_device);