core.c

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/*
 * Copyright (C) 2006 - 2007 Ivo van Doorn
 * Copyright (C) 2007 Dmitry Torokhov
 * Copyright 2009 Johannes Berg <[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/module.h>
#include <linux/init.h>
#include <linux/workqueue.h>
#include <linux/capability.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/rfkill.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/device.h>
#include <linux/miscdevice.h>
#include <linux/wait.h>
#include <linux/poll.h>
#include <linux/fs.h>
#include <linux/slab.h>

#include "rfkill.h"

#define POLL_INTERVAL       (5 * HZ)

#define RFKILL_BLOCK_HW     BIT(0)
#define RFKILL_BLOCK_SW     BIT(1)
#define RFKILL_BLOCK_SW_PREV    BIT(2)
#define RFKILL_BLOCK_ANY    (RFKILL_BLOCK_HW |\
                 RFKILL_BLOCK_SW |\
                 RFKILL_BLOCK_SW_PREV)
#define RFKILL_BLOCK_SW_SETCALL BIT(31)

struct rfkill {
    spinlock_t      lock;

    const char      *name;
    enum rfkill_type    type;

    unsigned long       state;

    u32         idx;

    bool            registered;
    bool            persistent;

    const struct rfkill_ops *ops;
    void            *data;

#ifdef CONFIG_RFKILL_LEDS
    struct led_trigger  led_trigger;
    const char      *ledtrigname;
#endif

    struct device       dev;
    struct list_head    node;

    struct delayed_work poll_work;
    struct work_struct  uevent_work;
    struct work_struct  sync_work;
};
#define to_rfkill(d)    container_of(d, struct rfkill, dev)

struct rfkill_int_event {
    struct list_head    list;
    struct rfkill_event ev;
};

struct rfkill_data {
    struct list_head    list;
    struct list_head    events;
    struct mutex        mtx;
    wait_queue_head_t   read_wait;
    bool            input_handler;
};


MODULE_AUTHOR("Ivo van Doorn <[email protected]>");
MODULE_AUTHOR("Johannes Berg <[email protected]>");
MODULE_DESCRIPTION("RF switch support");
MODULE_LICENSE("GPL");


/*
 * The locking here should be made much smarter, we currently have
 * a bit of a stupid situation because drivers might want to register
 * the rfkill struct under their own lock, and take this lock during
 * rfkill method calls -- which will cause an AB-BA deadlock situation.
 *
 * To fix that, we need to rework this code here to be mostly lock-free
 * and only use the mutex for list manipulations, not to protect the
 * various other global variables. Then we can avoid holding the mutex
 * around driver operations, and all is happy.
 */
static LIST_HEAD(rfkill_list);  /* list of registered rf switches */
static DEFINE_MUTEX(rfkill_global_mutex);
static LIST_HEAD(rfkill_fds);   /* list of open fds of /dev/rfkill */

static unsigned int rfkill_default_state = 1;
module_param_named(default_state, rfkill_default_state, uint, 0444);
MODULE_PARM_DESC(default_state,
         "Default initial state for all radio types, 0 = radio off");

static struct {
    bool cur, sav;
} rfkill_global_states[NUM_RFKILL_TYPES];

static bool rfkill_epo_lock_active;


#ifdef CONFIG_RFKILL_LEDS
static void rfkill_led_trigger_event(struct rfkill *rfkill)
{
    struct led_trigger *trigger;

    if (!rfkill->registered)
        return;

    trigger = &rfkill->led_trigger;

    if (rfkill->state & RFKILL_BLOCK_ANY)
        led_trigger_event(trigger, LED_OFF);
    else
        led_trigger_event(trigger, LED_FULL);
}

static void rfkill_led_trigger_activate(struct led_classdev *led)
{
    struct rfkill *rfkill;

    rfkill = container_of(led->trigger, struct rfkill, led_trigger);

    rfkill_led_trigger_event(rfkill);
}

const char *rfkill_get_led_trigger_name(struct rfkill *rfkill)
{
    return rfkill->led_trigger.name;
}
EXPORT_SYMBOL(rfkill_get_led_trigger_name);

void rfkill_set_led_trigger_name(struct rfkill *rfkill, const char *name)
{
    BUG_ON(!rfkill);

    rfkill->ledtrigname = name;
}
EXPORT_SYMBOL(rfkill_set_led_trigger_name);

static int rfkill_led_trigger_register(struct rfkill *rfkill)
{
    rfkill->led_trigger.name = rfkill->ledtrigname
                    ? : dev_name(&rfkill->dev);
    rfkill->led_trigger.activate = rfkill_led_trigger_activate;
    return led_trigger_register(&rfkill->led_trigger);
}

static void rfkill_led_trigger_unregister(struct rfkill *rfkill)
{
    led_trigger_unregister(&rfkill->led_trigger);
}
#else
static void rfkill_led_trigger_event(struct rfkill *rfkill)
{
}

static inline int rfkill_led_trigger_register(struct rfkill *rfkill)
{
    return 0;
}

static inline void rfkill_led_trigger_unregister(struct rfkill *rfkill)
{
}
#endif /* CONFIG_RFKILL_LEDS */

static void rfkill_fill_event(struct rfkill_event *ev, struct rfkill *rfkill,
                  enum rfkill_operation op)
{
    unsigned long flags;

    ev->idx = rfkill->idx;
    ev->type = rfkill->type;
    ev->op = op;

    spin_lock_irqsave(&rfkill->lock, flags);
    ev->hard = !!(rfkill->state & RFKILL_BLOCK_HW);
    ev->soft = !!(rfkill->state & (RFKILL_BLOCK_SW |
                    RFKILL_BLOCK_SW_PREV));
    spin_unlock_irqrestore(&rfkill->lock, flags);
}

static void rfkill_send_events(struct rfkill *rfkill, enum rfkill_operation op)
{
    struct rfkill_data *data;
    struct rfkill_int_event *ev;

    list_for_each_entry(data, &rfkill_fds, list) {
        ev = kzalloc(sizeof(*ev), GFP_KERNEL);
        if (!ev)
            continue;
        rfkill_fill_event(&ev->ev, rfkill, op);
        mutex_lock(&data->mtx);
        list_add_tail(&ev->list, &data->events);
        mutex_unlock(&data->mtx);
        wake_up_interruptible(&data->read_wait);
    }
}

static void rfkill_event(struct rfkill *rfkill)
{
    if (!rfkill->registered)
        return;

    kobject_uevent(&rfkill->dev.kobj, KOBJ_CHANGE);

    /* also send event to /dev/rfkill */
    rfkill_send_events(rfkill, RFKILL_OP_CHANGE);
}

static bool __rfkill_set_hw_state(struct rfkill *rfkill,
                  bool blocked, bool *change)
{
    unsigned long flags;
    bool prev, any;

    BUG_ON(!rfkill);

    spin_lock_irqsave(&rfkill->lock, flags);
    prev = !!(rfkill->state & RFKILL_BLOCK_HW);
    if (blocked)
        rfkill->state |= RFKILL_BLOCK_HW;
    else
        rfkill->state &= ~RFKILL_BLOCK_HW;
    *change = prev != blocked;
    any = !!(rfkill->state & RFKILL_BLOCK_ANY);
    spin_unlock_irqrestore(&rfkill->lock, flags);

    rfkill_led_trigger_event(rfkill);

    return any;
}

static void rfkill_set_block(struct rfkill *rfkill, bool blocked)
{
    unsigned long flags;
    bool prev, curr;
    int err;

    if (unlikely(rfkill->dev.power.power_state.event & PM_EVENT_SLEEP))
        return;

    /*
     * Some platforms (...!) generate input events which affect the
     * _hard_ kill state -- whenever something tries to change the
     * current software state query the hardware state too.
     */
    if (rfkill->ops->query)
        rfkill->ops->query(rfkill, rfkill->data);

    spin_lock_irqsave(&rfkill->lock, flags);
    prev = rfkill->state & RFKILL_BLOCK_SW;

    if (rfkill->state & RFKILL_BLOCK_SW)
        rfkill->state |= RFKILL_BLOCK_SW_PREV;
    else
        rfkill->state &= ~RFKILL_BLOCK_SW_PREV;

    if (blocked)
        rfkill->state |= RFKILL_BLOCK_SW;
    else
        rfkill->state &= ~RFKILL_BLOCK_SW;

    rfkill->state |= RFKILL_BLOCK_SW_SETCALL;
    spin_unlock_irqrestore(&rfkill->lock, flags);

    err = rfkill->ops->set_block(rfkill->data, blocked);

    spin_lock_irqsave(&rfkill->lock, flags);
    if (err) {
        /*
         * Failed -- reset status to _prev, this may be different
         * from what set set _PREV to earlier in this function
         * if rfkill_set_sw_state was invoked.
         */
        if (rfkill->state & RFKILL_BLOCK_SW_PREV)
            rfkill->state |= RFKILL_BLOCK_SW;
        else
            rfkill->state &= ~RFKILL_BLOCK_SW;
    }
    rfkill->state &= ~RFKILL_BLOCK_SW_SETCALL;
    rfkill->state &= ~RFKILL_BLOCK_SW_PREV;
    curr = rfkill->state & RFKILL_BLOCK_SW;
    spin_unlock_irqrestore(&rfkill->lock, flags);

    rfkill_led_trigger_event(rfkill);

    if (prev != curr)
        rfkill_event(rfkill);
}

#ifdef CONFIG_RFKILL_INPUT
static atomic_t rfkill_input_disabled = ATOMIC_INIT(0);

static void __rfkill_switch_all(const enum rfkill_type type, bool blocked)
{
    struct rfkill *rfkill;

    rfkill_global_states[type].cur = blocked;
    list_for_each_entry(rfkill, &rfkill_list, node) {
        if (rfkill->type != type && type != RFKILL_TYPE_ALL)
            continue;

        rfkill_set_block(rfkill, blocked);
    }
}

void rfkill_switch_all(enum rfkill_type type, bool blocked)
{
    if (atomic_read(&rfkill_input_disabled))
        return;

    mutex_lock(&rfkill_global_mutex);

    if (!rfkill_epo_lock_active)
        __rfkill_switch_all(type, blocked);

    mutex_unlock(&rfkill_global_mutex);
}

void rfkill_epo(void)
{
    struct rfkill *rfkill;
    int i;

    if (atomic_read(&rfkill_input_disabled))
        return;

    mutex_lock(&rfkill_global_mutex);

    rfkill_epo_lock_active = true;
    list_for_each_entry(rfkill, &rfkill_list, node)
        rfkill_set_block(rfkill, true);

    for (i = 0; i < NUM_RFKILL_TYPES; i++) {
        rfkill_global_states[i].sav = rfkill_global_states[i].cur;
        rfkill_global_states[i].cur = true;
    }

    mutex_unlock(&rfkill_global_mutex);
}

void rfkill_restore_states(void)
{
    int i;

    if (atomic_read(&rfkill_input_disabled))
        return;

    mutex_lock(&rfkill_global_mutex);

    rfkill_epo_lock_active = false;
    for (i = 0; i < NUM_RFKILL_TYPES; i++)
        __rfkill_switch_all(i, rfkill_global_states[i].sav);
    mutex_unlock(&rfkill_global_mutex);
}

void rfkill_remove_epo_lock(void)
{
    if (atomic_read(&rfkill_input_disabled))
        return;

    mutex_lock(&rfkill_global_mutex);
    rfkill_epo_lock_active = false;
    mutex_unlock(&rfkill_global_mutex);
}

bool rfkill_is_epo_lock_active(void)
{
    return rfkill_epo_lock_active;
}

bool rfkill_get_global_sw_state(const enum rfkill_type type)
{
    return rfkill_global_states[type].cur;
}
#endif


bool rfkill_set_hw_state(struct rfkill *rfkill, bool blocked)
{
    bool ret, change;

    ret = __rfkill_set_hw_state(rfkill, blocked, &change);

    if (!rfkill->registered)
        return ret;

    if (change)
        schedule_work(&rfkill->uevent_work);

    return ret;
}
EXPORT_SYMBOL(rfkill_set_hw_state);

static void __rfkill_set_sw_state(struct rfkill *rfkill, bool blocked)
{
    u32 bit = RFKILL_BLOCK_SW;

    /* if in a ops->set_block right now, use other bit */
    if (rfkill->state & RFKILL_BLOCK_SW_SETCALL)
        bit = RFKILL_BLOCK_SW_PREV;

    if (blocked)
        rfkill->state |= bit;
    else
        rfkill->state &= ~bit;
}

bool rfkill_set_sw_state(struct rfkill *rfkill, bool blocked)
{
    unsigned long flags;
    bool prev, hwblock;

    BUG_ON(!rfkill);

    spin_lock_irqsave(&rfkill->lock, flags);
    prev = !!(rfkill->state & RFKILL_BLOCK_SW);
    __rfkill_set_sw_state(rfkill, blocked);
    hwblock = !!(rfkill->state & RFKILL_BLOCK_HW);
    blocked = blocked || hwblock;
    spin_unlock_irqrestore(&rfkill->lock, flags);

    if (!rfkill->registered)
        return blocked;

    if (prev != blocked && !hwblock)
        schedule_work(&rfkill->uevent_work);

    rfkill_led_trigger_event(rfkill);

    return blocked;
}
EXPORT_SYMBOL(rfkill_set_sw_state);

void rfkill_init_sw_state(struct rfkill *rfkill, bool blocked)
{
    unsigned long flags;

    BUG_ON(!rfkill);
    BUG_ON(rfkill->registered);

    spin_lock_irqsave(&rfkill->lock, flags);
    __rfkill_set_sw_state(rfkill, blocked);
    rfkill->persistent = true;
    spin_unlock_irqrestore(&rfkill->lock, flags);
}
EXPORT_SYMBOL(rfkill_init_sw_state);

void rfkill_set_states(struct rfkill *rfkill, bool sw, bool hw)
{
    unsigned long flags;
    bool swprev, hwprev;

    BUG_ON(!rfkill);

    spin_lock_irqsave(&rfkill->lock, flags);

    /*
     * No need to care about prev/setblock ... this is for uevent only
     * and that will get triggered by rfkill_set_block anyway.
     */
    swprev = !!(rfkill->state & RFKILL_BLOCK_SW);
    hwprev = !!(rfkill->state & RFKILL_BLOCK_HW);
    __rfkill_set_sw_state(rfkill, sw);
    if (hw)
        rfkill->state |= RFKILL_BLOCK_HW;
    else
        rfkill->state &= ~RFKILL_BLOCK_HW;

    spin_unlock_irqrestore(&rfkill->lock, flags);

    if (!rfkill->registered) {
        rfkill->persistent = true;
    } else {
        if (swprev != sw || hwprev != hw)
            schedule_work(&rfkill->uevent_work);

        rfkill_led_trigger_event(rfkill);
    }
}
EXPORT_SYMBOL(rfkill_set_states);

static ssize_t rfkill_name_show(struct device *dev,
                struct device_attribute *attr,
                char *buf)
{
    struct rfkill *rfkill = to_rfkill(dev);

    return sprintf(buf, "%s\n", rfkill->name);
}

static const char *rfkill_get_type_str(enum rfkill_type type)
{
    BUILD_BUG_ON(NUM_RFKILL_TYPES != RFKILL_TYPE_FM + 1);

    switch (type) {
    case RFKILL_TYPE_WLAN:
        return "wlan";
    case RFKILL_TYPE_BLUETOOTH:
        return "bluetooth";
    case RFKILL_TYPE_UWB:
        return "ultrawideband";
    case RFKILL_TYPE_WIMAX:
        return "wimax";
    case RFKILL_TYPE_WWAN:
        return "wwan";
    case RFKILL_TYPE_GPS:
        return "gps";
    case RFKILL_TYPE_FM:
        return "fm";
    default:
        BUG();
    }
}

static ssize_t rfkill_type_show(struct device *dev,
                struct device_attribute *attr,
                char *buf)
{
    struct rfkill *rfkill = to_rfkill(dev);

    return sprintf(buf, "%s\n", rfkill_get_type_str(rfkill->type));
}

static ssize_t rfkill_idx_show(struct device *dev,
                   struct device_attribute *attr,
                   char *buf)
{
    struct rfkill *rfkill = to_rfkill(dev);

    return sprintf(buf, "%d\n", rfkill->idx);
}

static ssize_t rfkill_persistent_show(struct device *dev,
                   struct device_attribute *attr,
                   char *buf)
{
    struct rfkill *rfkill = to_rfkill(dev);

    return sprintf(buf, "%d\n", rfkill->persistent);
}

static ssize_t rfkill_hard_show(struct device *dev,
                 struct device_attribute *attr,
                 char *buf)
{
    struct rfkill *rfkill = to_rfkill(dev);

    return sprintf(buf, "%d\n", (rfkill->state & RFKILL_BLOCK_HW) ? 1 : 0 );
}

static ssize_t rfkill_soft_show(struct device *dev,
                 struct device_attribute *attr,
                 char *buf)
{
    struct rfkill *rfkill = to_rfkill(dev);

    return sprintf(buf, "%d\n", (rfkill->state & RFKILL_BLOCK_SW) ? 1 : 0 );
}

static ssize_t rfkill_soft_store(struct device *dev,
                  struct device_attribute *attr,
                  const char *buf, size_t count)
{
    struct rfkill *rfkill = to_rfkill(dev);
    unsigned long state;
    int err;

    if (!capable(CAP_NET_ADMIN))
        return -EPERM;

    err = kstrtoul(buf, 0, &state);
    if (err)
        return err;

    if (state > 1 )
        return -EINVAL;

    mutex_lock(&rfkill_global_mutex);
    rfkill_set_block(rfkill, state);
    mutex_unlock(&rfkill_global_mutex);

    return err ?: count;
}

static u8 user_state_from_blocked(unsigned long state)
{
    if (state & RFKILL_BLOCK_HW)
        return RFKILL_USER_STATE_HARD_BLOCKED;
    if (state & RFKILL_BLOCK_SW)
        return RFKILL_USER_STATE_SOFT_BLOCKED;

    return RFKILL_USER_STATE_UNBLOCKED;
}

static ssize_t rfkill_state_show(struct device *dev,
                 struct device_attribute *attr,
                 char *buf)
{
    struct rfkill *rfkill = to_rfkill(dev);

    return sprintf(buf, "%d\n", user_state_from_blocked(rfkill->state));
}

static ssize_t rfkill_state_store(struct device *dev,
                  struct device_attribute *attr,
                  const char *buf, size_t count)
{
    struct rfkill *rfkill = to_rfkill(dev);
    unsigned long state;
    int err;

    if (!capable(CAP_NET_ADMIN))
        return -EPERM;

    err = kstrtoul(buf, 0, &state);
    if (err)
        return err;

    if (state != RFKILL_USER_STATE_SOFT_BLOCKED &&
        state != RFKILL_USER_STATE_UNBLOCKED)
        return -EINVAL;

    mutex_lock(&rfkill_global_mutex);
    rfkill_set_block(rfkill, state == RFKILL_USER_STATE_SOFT_BLOCKED);
    mutex_unlock(&rfkill_global_mutex);

    return err ?: count;
}

static ssize_t rfkill_claim_show(struct device *dev,
                 struct device_attribute *attr,
                 char *buf)
{
    return sprintf(buf, "%d\n", 0);
}

static ssize_t rfkill_claim_store(struct device *dev,
                  struct device_attribute *attr,
                  const char *buf, size_t count)
{
    return -EOPNOTSUPP;
}

static struct device_attribute rfkill_dev_attrs[] = {
    __ATTR(name, S_IRUGO, rfkill_name_show, NULL),
    __ATTR(type, S_IRUGO, rfkill_type_show, NULL),
    __ATTR(index, S_IRUGO, rfkill_idx_show, NULL),
    __ATTR(persistent, S_IRUGO, rfkill_persistent_show, NULL),
    __ATTR(state, S_IRUGO|S_IWUSR, rfkill_state_show, rfkill_state_store),
    __ATTR(claim, S_IRUGO|S_IWUSR, rfkill_claim_show, rfkill_claim_store),
    __ATTR(soft, S_IRUGO|S_IWUSR, rfkill_soft_show, rfkill_soft_store),
    __ATTR(hard, S_IRUGO, rfkill_hard_show, NULL),
    __ATTR_NULL
};

static void rfkill_release(struct device *dev)
{
    struct rfkill *rfkill = to_rfkill(dev);

    kfree(rfkill);
}

static int rfkill_dev_uevent(struct device *dev, struct kobj_uevent_env *env)
{
    struct rfkill *rfkill = to_rfkill(dev);
    unsigned long flags;
    u32 state;
    int error;

    error = add_uevent_var(env, "RFKILL_NAME=%s", rfkill->name);
    if (error)
        return error;
    error = add_uevent_var(env, "RFKILL_TYPE=%s",
                   rfkill_get_type_str(rfkill->type));
    if (error)
        return error;
    spin_lock_irqsave(&rfkill->lock, flags);
    state = rfkill->state;
    spin_unlock_irqrestore(&rfkill->lock, flags);
    error = add_uevent_var(env, "RFKILL_STATE=%d",
                   user_state_from_blocked(state));
    return error;
}

void rfkill_pause_polling(struct rfkill *rfkill)
{
    BUG_ON(!rfkill);

    if (!rfkill->ops->poll)
        return;

    cancel_delayed_work_sync(&rfkill->poll_work);
}
EXPORT_SYMBOL(rfkill_pause_polling);

void rfkill_resume_polling(struct rfkill *rfkill)
{
    BUG_ON(!rfkill);

    if (!rfkill->ops->poll)
        return;

    schedule_work(&rfkill->poll_work.work);
}
EXPORT_SYMBOL(rfkill_resume_polling);

static int rfkill_suspend(struct device *dev, pm_message_t state)
{
    struct rfkill *rfkill = to_rfkill(dev);

    rfkill_pause_polling(rfkill);

    return 0;
}

static int rfkill_resume(struct device *dev)
{
    struct rfkill *rfkill = to_rfkill(dev);
    bool cur;

    if (!rfkill->persistent) {
        cur = !!(rfkill->state & RFKILL_BLOCK_SW);
        rfkill_set_block(rfkill, cur);
    }

    rfkill_resume_polling(rfkill);

    return 0;
}

static struct class rfkill_class = {
    .name       = "rfkill",
    .dev_release    = rfkill_release,
    .dev_attrs  = rfkill_dev_attrs,
    .dev_uevent = rfkill_dev_uevent,
    .suspend    = rfkill_suspend,
    .resume     = rfkill_resume,
};

bool rfkill_blocked(struct rfkill *rfkill)
{
    unsigned long flags;
    u32 state;

    spin_lock_irqsave(&rfkill->lock, flags);
    state = rfkill->state;
    spin_unlock_irqrestore(&rfkill->lock, flags);

    return !!(state & RFKILL_BLOCK_ANY);
}
EXPORT_SYMBOL(rfkill_blocked);


struct rfkill * __must_check rfkill_alloc(const char *name,
                      struct device *parent,
                      const enum rfkill_type type,
                      const struct rfkill_ops *ops,
                      void *ops_data)
{
    struct rfkill *rfkill;
    struct device *dev;

    if (WARN_ON(!ops))
        return NULL;

    if (WARN_ON(!ops->set_block))
        return NULL;

    if (WARN_ON(!name))
        return NULL;

    if (WARN_ON(type == RFKILL_TYPE_ALL || type >= NUM_RFKILL_TYPES))
        return NULL;

    rfkill = kzalloc(sizeof(*rfkill), GFP_KERNEL);
    if (!rfkill)
        return NULL;

    spin_lock_init(&rfkill->lock);
    INIT_LIST_HEAD(&rfkill->node);
    rfkill->type = type;
    rfkill->name = name;
    rfkill->ops = ops;
    rfkill->data = ops_data;

    dev = &rfkill->dev;
    dev->class = &rfkill_class;
    dev->parent = parent;
    device_initialize(dev);

    return rfkill;
}
EXPORT_SYMBOL(rfkill_alloc);

static void rfkill_poll(struct work_struct *work)
{
    struct rfkill *rfkill;

    rfkill = container_of(work, struct rfkill, poll_work.work);

    /*
     * Poll hardware state -- driver will use one of the
     * rfkill_set{,_hw,_sw}_state functions and use its
     * return value to update the current status.
     */
    rfkill->ops->poll(rfkill, rfkill->data);

    schedule_delayed_work(&rfkill->poll_work,
        round_jiffies_relative(POLL_INTERVAL));
}

static void rfkill_uevent_work(struct work_struct *work)
{
    struct rfkill *rfkill;

    rfkill = container_of(work, struct rfkill, uevent_work);

    mutex_lock(&rfkill_global_mutex);
    rfkill_event(rfkill);
    mutex_unlock(&rfkill_global_mutex);
}

static void rfkill_sync_work(struct work_struct *work)
{
    struct rfkill *rfkill;
    bool cur;

    rfkill = container_of(work, struct rfkill, sync_work);

    mutex_lock(&rfkill_global_mutex);
    cur = rfkill_global_states[rfkill->type].cur;
    rfkill_set_block(rfkill, cur);
    mutex_unlock(&rfkill_global_mutex);
}

int __must_check rfkill_register(struct rfkill *rfkill)
{
    static unsigned long rfkill_no;
    struct device *dev = &rfkill->dev;
    int error;

    BUG_ON(!rfkill);

    mutex_lock(&rfkill_global_mutex);

    if (rfkill->registered) {
        error = -EALREADY;
        goto unlock;
    }

    rfkill->idx = rfkill_no;
    dev_set_name(dev, "rfkill%lu", rfkill_no);
    rfkill_no++;

    list_add_tail(&rfkill->node, &rfkill_list);

    error = device_add(dev);
    if (error)
        goto remove;

    error = rfkill_led_trigger_register(rfkill);
    if (error)
        goto devdel;

    rfkill->registered = true;

    INIT_DELAYED_WORK(&rfkill->poll_work, rfkill_poll);
    INIT_WORK(&rfkill->uevent_work, rfkill_uevent_work);
    INIT_WORK(&rfkill->sync_work, rfkill_sync_work);

    if (rfkill->ops->poll)
        schedule_delayed_work(&rfkill->poll_work,
            round_jiffies_relative(POLL_INTERVAL));

    if (!rfkill->persistent || rfkill_epo_lock_active) {
        schedule_work(&rfkill->sync_work);
    } else {
#ifdef CONFIG_RFKILL_INPUT
        bool soft_blocked = !!(rfkill->state & RFKILL_BLOCK_SW);

        if (!atomic_read(&rfkill_input_disabled))
            __rfkill_switch_all(rfkill->type, soft_blocked);
#endif
    }

    rfkill_send_events(rfkill, RFKILL_OP_ADD);

    mutex_unlock(&rfkill_global_mutex);
    return 0;

 devdel:
    device_del(&rfkill->dev);
 remove:
    list_del_init(&rfkill->node);
 unlock:
    mutex_unlock(&rfkill_global_mutex);
    return error;
}
EXPORT_SYMBOL(rfkill_register);

void rfkill_unregister(struct rfkill *rfkill)
{
    BUG_ON(!rfkill);

    if (rfkill->ops->poll)
        cancel_delayed_work_sync(&rfkill->poll_work);

    cancel_work_sync(&rfkill->uevent_work);
    cancel_work_sync(&rfkill->sync_work);

    rfkill->registered = false;

    device_del(&rfkill->dev);

    mutex_lock(&rfkill_global_mutex);
    rfkill_send_events(rfkill, RFKILL_OP_DEL);
    list_del_init(&rfkill->node);
    mutex_unlock(&rfkill_global_mutex);

    rfkill_led_trigger_unregister(rfkill);
}
EXPORT_SYMBOL(rfkill_unregister);

void rfkill_destroy(struct rfkill *rfkill)
{
    if (rfkill)
        put_device(&rfkill->dev);
}
EXPORT_SYMBOL(rfkill_destroy);

static int rfkill_fop_open(struct inode *inode, struct file *file)
{
    struct rfkill_data *data;
    struct rfkill *rfkill;
    struct rfkill_int_event *ev, *tmp;

    data = kzalloc(sizeof(*data), GFP_KERNEL);
    if (!data)
        return -ENOMEM;

    INIT_LIST_HEAD(&data->events);
    mutex_init(&data->mtx);
    init_waitqueue_head(&data->read_wait);

    mutex_lock(&rfkill_global_mutex);
    mutex_lock(&data->mtx);
    /*
     * start getting events from elsewhere but hold mtx to get
     * startup events added first
     */

    list_for_each_entry(rfkill, &rfkill_list, node) {
        ev = kzalloc(sizeof(*ev), GFP_KERNEL);
        if (!ev)
            goto free;
        rfkill_fill_event(&ev->ev, rfkill, RFKILL_OP_ADD);
        list_add_tail(&ev->list, &data->events);
    }
    list_add(&data->list, &rfkill_fds);
    mutex_unlock(&data->mtx);
    mutex_unlock(&rfkill_global_mutex);

    file->private_data = data;

    return nonseekable_open(inode, file);

 free:
    mutex_unlock(&data->mtx);
    mutex_unlock(&rfkill_global_mutex);
    mutex_destroy(&data->mtx);
    list_for_each_entry_safe(ev, tmp, &data->events, list)
        kfree(ev);
    kfree(data);
    return -ENOMEM;
}

static unsigned int rfkill_fop_poll(struct file *file, poll_table *wait)
{
    struct rfkill_data *data = file->private_data;
    unsigned int res = POLLOUT | POLLWRNORM;

    poll_wait(file, &data->read_wait, wait);

    mutex_lock(&data->mtx);
    if (!list_empty(&data->events))
        res = POLLIN | POLLRDNORM;
    mutex_unlock(&data->mtx);

    return res;
}

static bool rfkill_readable(struct rfkill_data *data)
{
    bool r;

    mutex_lock(&data->mtx);
    r = !list_empty(&data->events);
    mutex_unlock(&data->mtx);

    return r;
}

static ssize_t rfkill_fop_read(struct file *file, char __user *buf,
                   size_t count, loff_t *pos)
{
    struct rfkill_data *data = file->private_data;
    struct rfkill_int_event *ev;
    unsigned long sz;
    int ret;

    mutex_lock(&data->mtx);

    while (list_empty(&data->events)) {
        if (file->f_flags & O_NONBLOCK) {
            ret = -EAGAIN;
            goto out;
        }
        mutex_unlock(&data->mtx);
        ret = wait_event_interruptible(data->read_wait,
                           rfkill_readable(data));
        mutex_lock(&data->mtx);

        if (ret)
            goto out;
    }

    ev = list_first_entry(&data->events, struct rfkill_int_event,
                list);

    sz = min_t(unsigned long, sizeof(ev->ev), count);
    ret = sz;
    if (copy_to_user(buf, &ev->ev, sz))
        ret = -EFAULT;

    list_del(&ev->list);
    kfree(ev);
 out:
    mutex_unlock(&data->mtx);
    return ret;
}

static ssize_t rfkill_fop_write(struct file *file, const char __user *buf,
                size_t count, loff_t *pos)
{
    struct rfkill *rfkill;
    struct rfkill_event ev;

    /* we don't need the 'hard' variable but accept it */
    if (count < RFKILL_EVENT_SIZE_V1 - 1)
        return -EINVAL;

    /*
     * Copy as much data as we can accept into our 'ev' buffer,
     * but tell userspace how much we've copied so it can determine
     * our API version even in a write() call, if it cares.
     */
    count = min(count, sizeof(ev));
    if (copy_from_user(&ev, buf, count))
        return -EFAULT;

    if (ev.op != RFKILL_OP_CHANGE && ev.op != RFKILL_OP_CHANGE_ALL)
        return -EINVAL;

    if (ev.type >= NUM_RFKILL_TYPES)
        return -EINVAL;

    mutex_lock(&rfkill_global_mutex);

    if (ev.op == RFKILL_OP_CHANGE_ALL) {
        if (ev.type == RFKILL_TYPE_ALL) {
            enum rfkill_type i;
            for (i = 0; i < NUM_RFKILL_TYPES; i++)
                rfkill_global_states[i].cur = ev.soft;
        } else {
            rfkill_global_states[ev.type].cur = ev.soft;
        }
    }

    list_for_each_entry(rfkill, &rfkill_list, node) {
        if (rfkill->idx != ev.idx && ev.op != RFKILL_OP_CHANGE_ALL)
            continue;

        if (rfkill->type != ev.type && ev.type != RFKILL_TYPE_ALL)
            continue;

        rfkill_set_block(rfkill, ev.soft);
    }
    mutex_unlock(&rfkill_global_mutex);

    return count;
}

static int rfkill_fop_release(struct inode *inode, struct file *file)
{
    struct rfkill_data *data = file->private_data;
    struct rfkill_int_event *ev, *tmp;

    mutex_lock(&rfkill_global_mutex);
    list_del(&data->list);
    mutex_unlock(&rfkill_global_mutex);

    mutex_destroy(&data->mtx);
    list_for_each_entry_safe(ev, tmp, &data->events, list)
        kfree(ev);

#ifdef CONFIG_RFKILL_INPUT
    if (data->input_handler)
        if (atomic_dec_return(&rfkill_input_disabled) == 0)
            printk(KERN_DEBUG "rfkill: input handler enabled\n");
#endif

    kfree(data);

    return 0;
}

#ifdef CONFIG_RFKILL_INPUT
static long rfkill_fop_ioctl(struct file *file, unsigned int cmd,
                 unsigned long arg)
{
    struct rfkill_data *data = file->private_data;

    if (_IOC_TYPE(cmd) != RFKILL_IOC_MAGIC)
        return -ENOSYS;

    if (_IOC_NR(cmd) != RFKILL_IOC_NOINPUT)
        return -ENOSYS;

    mutex_lock(&data->mtx);

    if (!data->input_handler) {
        if (atomic_inc_return(&rfkill_input_disabled) == 1)
            printk(KERN_DEBUG "rfkill: input handler disabled\n");
        data->input_handler = true;
    }

    mutex_unlock(&data->mtx);

    return 0;
}
#endif

static const struct file_operations rfkill_fops = {
    .owner      = THIS_MODULE,
    .open       = rfkill_fop_open,
    .read       = rfkill_fop_read,
    .write      = rfkill_fop_write,
    .poll       = rfkill_fop_poll,
    .release    = rfkill_fop_release,
#ifdef CONFIG_RFKILL_INPUT
    .unlocked_ioctl = rfkill_fop_ioctl,
    .compat_ioctl   = rfkill_fop_ioctl,
#endif
    .llseek     = no_llseek,
};

static struct miscdevice rfkill_miscdev = {
    .name   = "rfkill",
    .fops   = &rfkill_fops,
    .minor  = MISC_DYNAMIC_MINOR,
};

static int __init rfkill_init(void)
{
    int error;
    int i;

    for (i = 0; i < NUM_RFKILL_TYPES; i++)
        rfkill_global_states[i].cur = !rfkill_default_state;

    error = class_register(&rfkill_class);
    if (error)
        goto out;

    error = misc_register(&rfkill_miscdev);
    if (error) {
        class_unregister(&rfkill_class);
        goto out;
    }

#ifdef CONFIG_RFKILL_INPUT
    error = rfkill_handler_init();
    if (error) {
        misc_deregister(&rfkill_miscdev);
        class_unregister(&rfkill_class);
        goto out;
    }
#endif

 out:
    return error;
}
subsys_initcall(rfkill_init);

static void __exit rfkill_exit(void)
{
#ifdef CONFIG_RFKILL_INPUT
    rfkill_handler_exit();
#endif
    misc_deregister(&rfkill_miscdev);
    class_unregister(&rfkill_class);
}
module_exit(rfkill_exit);