rfkill: rewrite

This patch completely rewrites the rfkill core to address
the following deficiencies:

 * all rfkill drivers need to implement polling where necessary
   rather than having one central implementation

 * updating the rfkill state cannot be done from arbitrary
   contexts, forcing drivers to use schedule_work and requiring
   lots of code

 * rfkill drivers need to keep track of soft/hard blocked
   internally -- the core should do this

 * the rfkill API has many unexpected quirks, for example being
   asymmetric wrt. alloc/free and register/unregister

 * rfkill can call back into a driver from within a function the
   driver called -- this is prone to deadlocks and generally
   should be avoided

 * rfkill-input pointlessly is a separate module

 * drivers need to #ifdef rfkill functions (unless they want to
   depend on or select RFKILL) -- rfkill should provide inlines
   that do nothing if it isn't compiled in

 * the rfkill structure is not opaque -- drivers need to initialise
   it correctly (lots of sanity checking code required) -- instead
   force drivers to pass the right variables to rfkill_alloc()

 * the documentation is hard to read because it always assumes the
   reader is completely clueless and contains way TOO MANY CAPS

 * the rfkill code needlessly uses a lot of locks and atomic
   operations in locked sections

 * fix LED trigger to actually change the LED when the radio state
   changes -- this wasn't done before

Tested-by: Alan Jenkins <alan-jenkins@tuffmail.co.uk>
Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br> [thinkpad]
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 896 insertions, 0 deletions

diff --git a/net/rfkill/core.c b/net/rfkill/core.c
new file mode 100644
index 000000000000..30a6f8d819b2
--- /dev/null
+++ b/net/rfkill/core.c
@@ -0,0 +1,896 @@
+/*
+ * Copyright (C) 2006 - 2007 Ivo van Doorn
+ * Copyright (C) 2007 Dmitry Torokhov
+ * Copyright 2009 Johannes Berg <johannes@sipsolutions.net>
+ *
+ * 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/spinlock.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;
+
+        bool                    registered;
+        bool                    suspended;
+
+        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)
+
+
+
+MODULE_AUTHOR("Ivo van Doorn <IvDoorn@gmail.com>");
+MODULE_AUTHOR("Johannes Berg <johannes@sipsolutions.net>");
+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 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, def;
+} rfkill_global_states[NUM_RFKILL_TYPES];
+
+static unsigned long rfkill_states_default_locked;
+
+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_uevent(struct rfkill *rfkill)
+{
+        if (!rfkill->registered || rfkill->suspended)
+                return;
+
+        kobject_uevent(&rfkill->dev.kobj, KOBJ_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;
+}
+
+/**
+ * rfkill_set_block - wrapper for set_block method
+ *
+ * @rfkill: the rfkill struct to use
+ * @blocked: the new software state
+ *
+ * Calls the set_block method (when applicable) and handles notifications
+ * etc. as well.
+ */
+static void rfkill_set_block(struct rfkill *rfkill, bool blocked)
+{
+        unsigned long flags;
+        int err;
+
+        /*
+         * 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);
+        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);
+
+        if (unlikely(rfkill->dev.power.power_state.event & PM_EVENT_SLEEP))
+                return;
+
+        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;
+        spin_unlock_irqrestore(&rfkill->lock, flags);
+
+        rfkill_led_trigger_event(rfkill);
+        rfkill_uevent(rfkill);
+}
+
+/**
+ * __rfkill_switch_all - Toggle state of all switches of given type
+ * @type: type of interfaces to be affected
+ * @state: the new state
+ *
+ * This function sets the state of all switches of given type,
+ * unless a specific switch is claimed by userspace (in which case,
+ * that switch is left alone) or suspended.
+ *
+ * Caller must have acquired rfkill_global_mutex.
+ */
+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)
+                        continue;
+
+                rfkill_set_block(rfkill, blocked);
+        }
+}
+
+/**
+ * rfkill_switch_all - Toggle state of all switches of given type
+ * @type: type of interfaces to be affected
+ * @state: the new state
+ *
+ * Acquires rfkill_global_mutex and calls __rfkill_switch_all(@type, @state).
+ * Please refer to __rfkill_switch_all() for details.
+ *
+ * Does nothing if the EPO lock is active.
+ */
+void rfkill_switch_all(enum rfkill_type type, bool blocked)
+{
+        mutex_lock(&rfkill_global_mutex);
+
+        if (!rfkill_epo_lock_active)
+                __rfkill_switch_all(type, blocked);
+
+        mutex_unlock(&rfkill_global_mutex);
+}
+
+/**
+ * rfkill_epo - emergency power off all transmitters
+ *
+ * This kicks all non-suspended rfkill devices to RFKILL_STATE_SOFT_BLOCKED,
+ * ignoring everything in its path but rfkill_global_mutex and rfkill->mutex.
+ *
+ * The global state before the EPO is saved and can be restored later
+ * using rfkill_restore_states().
+ */
+void rfkill_epo(void)
+{
+        struct rfkill *rfkill;
+        int i;
+
+        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].def = rfkill_global_states[i].cur;
+                rfkill_global_states[i].cur = true;
+        }
+        mutex_unlock(&rfkill_global_mutex);
+}
+
+/**
+ * rfkill_restore_states - restore global states
+ *
+ * Restore (and sync switches to) the global state from the
+ * states in rfkill_default_states.  This can undo the effects of
+ * a call to rfkill_epo().
+ */
+void rfkill_restore_states(void)
+{
+        int i;
+
+        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].def);
+        mutex_unlock(&rfkill_global_mutex);
+}
+
+/**
+ * rfkill_remove_epo_lock - unlock state changes
+ *
+ * Used by rfkill-input manually unlock state changes, when
+ * the EPO switch is deactivated.
+ */
+void rfkill_remove_epo_lock(void)
+{
+        mutex_lock(&rfkill_global_mutex);
+        rfkill_epo_lock_active = false;
+        mutex_unlock(&rfkill_global_mutex);
+}
+
+/**
+ * rfkill_is_epo_lock_active - returns true EPO is active
+ *
+ * Returns 0 (false) if there is NOT an active EPO contidion,
+ * and 1 (true) if there is an active EPO contition, which
+ * locks all radios in one of the BLOCKED states.
+ *
+ * Can be called in atomic context.
+ */
+bool rfkill_is_epo_lock_active(void)
+{
+        return rfkill_epo_lock_active;
+}
+
+/**
+ * rfkill_get_global_sw_state - returns global state for a type
+ * @type: the type to get the global state of
+ *
+ * Returns the current global state for a given wireless
+ * device type.
+ */
+bool rfkill_get_global_sw_state(const enum rfkill_type type)
+{
+        return rfkill_global_states[type].cur;
+}
+
+void rfkill_set_global_sw_state(const enum rfkill_type type, bool blocked)
+{
+        mutex_lock(&rfkill_global_mutex);
+
+        /* don't allow unblock when epo */
+        if (rfkill_epo_lock_active && !blocked)
+                goto out;
+
+        /* too late */
+        if (rfkill_states_default_locked & BIT(type))
+                goto out;
+
+        rfkill_states_default_locked |= BIT(type);
+
+        rfkill_global_states[type].cur = blocked;
+        rfkill_global_states[type].def = blocked;
+ out:
+        mutex_unlock(&rfkill_global_mutex);
+}
+EXPORT_SYMBOL(rfkill_set_global_sw_state);
+
+
+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_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);
+
+        spin_unlock_irqrestore(&rfkill->lock, flags);
+
+        if (!rfkill->registered)
+                return;
+
+        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)
+{
+        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";
+        default:
+                BUG();
+        }
+
+        BUILD_BUG_ON(NUM_RFKILL_TYPES != RFKILL_TYPE_WWAN + 1);
+}
+
+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 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);
+        unsigned long flags;
+        u32 state;
+
+        spin_lock_irqsave(&rfkill->lock, flags);
+        state = rfkill->state;
+        spin_unlock_irqrestore(&rfkill->lock, flags);
+
+        return sprintf(buf, "%d\n", user_state_from_blocked(state));
+}
+
+static ssize_t rfkill_state_store(struct device *dev,
+                                  struct device_attribute *attr,
+                                  const char *buf, size_t count)
+{
+        /*
+         * The intention was that userspace can only take control over
+         * a given device when/if rfkill-input doesn't control it due
+         * to user_claim. Since user_claim is currently unsupported,
+         * we never support changing the state from userspace -- this
+         * can be implemented again later.
+         */
+
+        return -EPERM;
+}
+
+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(state, S_IRUGO|S_IWUSR, rfkill_state_show, rfkill_state_store),
+        __ATTR(claim, S_IRUGO|S_IWUSR, rfkill_claim_show, rfkill_claim_store),
+        __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);
+
+        rfkill->suspended = true;
+
+        return 0;
+}
+
+static int rfkill_resume(struct device *dev)
+{
+        struct rfkill *rfkill = to_rfkill(dev);
+        bool cur;
+
+        mutex_lock(&rfkill_global_mutex);
+        cur = rfkill_global_states[rfkill->type].cur;
+        rfkill_set_block(rfkill, cur);
+        mutex_unlock(&rfkill_global_mutex);
+
+        rfkill->suspended = false;
+
+        schedule_work(&rfkill->uevent_work);
+
+        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,
+};
+
+
+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 >= 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);
+
+        rfkill_uevent(rfkill);
+}
+
+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;
+        }
+
+        dev_set_name(dev, "rfkill%lu", rfkill_no);
+        rfkill_no++;
+
+        if (!(rfkill_states_default_locked & BIT(rfkill->type))) {
+                /* first of its kind */
+                BUILD_BUG_ON(NUM_RFKILL_TYPES >
+                        sizeof(rfkill_states_default_locked) * 8);
+                rfkill_states_default_locked |= BIT(rfkill->type);
+                rfkill_global_states[rfkill->type].cur =
+                        rfkill_global_states[rfkill->type].def;
+        }
+
+        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;
+
+        if (rfkill->ops->poll) {
+                INIT_DELAYED_WORK(&rfkill->poll_work, rfkill_poll);
+                schedule_delayed_work(&rfkill->poll_work,
+                        round_jiffies_relative(POLL_INTERVAL));
+        }
+
+        INIT_WORK(&rfkill->uevent_work, rfkill_uevent_work);
+
+        INIT_WORK(&rfkill->sync_work, rfkill_sync_work);
+        schedule_work(&rfkill->sync_work);
+
+        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);
+        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 __init rfkill_init(void)
+{
+        int error;
+        int i;
+
+        for (i = 0; i < NUM_RFKILL_TYPES; i++)
+                rfkill_global_states[i].def = !rfkill_default_state;
+
+        error = class_register(&rfkill_class);
+        if (error)
+                goto out;
+
+#ifdef CONFIG_RFKILL_INPUT
+        error = rfkill_handler_init();
+        if (error)
+                class_unregister(&rfkill_class);
+#endif
+
+ out:
+        return error;
+}
+subsys_initcall(rfkill_init);
+
+static void __exit rfkill_exit(void)
+{
+#ifdef CONFIG_RFKILL_INPUT
+        rfkill_handler_exit();
+#endif
+        class_unregister(&rfkill_class);
+}
+module_exit(rfkill_exit);