/*
 * Copyright (C) 2011 Instituto Nokia de Tecnologia
 *
 * Authors:
 *    Lauro Ramos Venancio <lauro.venancio@openbossa.org>
 *    Aloisio Almeida Jr <aloisio.almeida@openbossa.org>
 *
 * 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.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": %s: " fmt, __func__

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/rfkill.h>
#include <linux/nfc.h>

#include <net/genetlink.h>

#include "nfc.h"

#define VERSION "0.1"

#define NFC_CHECK_PRES_FREQ_MS  2000

int nfc_devlist_generation;
DEFINE_MUTEX(nfc_devlist_mutex);

/* NFC device ID bitmap */
static DEFINE_IDA(nfc_index_ida);

int nfc_fw_download(struct nfc_dev *dev, const char *firmware_name)
{
        int rc = 0;

        pr_debug("%s do firmware %s\n", dev_name(&dev->dev), firmware_name);

        device_lock(&dev->dev);

        if (!device_is_registered(&dev->dev)) {
                rc = -ENODEV;
                goto error;
        }

        if (dev->dev_up) {
                rc = -EBUSY;
                goto error;
        }

        if (!dev->ops->fw_download) {
                rc = -EOPNOTSUPP;
                goto error;
        }

        dev->fw_download_in_progress = true;
        rc = dev->ops->fw_download(dev, firmware_name);
        if (rc)
                dev->fw_download_in_progress = false;

error:
        device_unlock(&dev->dev);
        return rc;
}

/**
 * nfc_fw_download_done - inform that a firmware download was completed
 *
 * @dev: The nfc device to which firmware was downloaded
 * @firmware_name: The firmware filename
 * @result: The positive value of a standard errno value
 */
int nfc_fw_download_done(struct nfc_dev *dev, const char *firmware_name,
                         u32 result)
{
        dev->fw_download_in_progress = false;

        return nfc_genl_fw_download_done(dev, firmware_name, result);
}
EXPORT_SYMBOL(nfc_fw_download_done);

/**
 * nfc_dev_up - turn on the NFC device
 *
 * @dev: The nfc device to be turned on
 *
 * The device remains up until the nfc_dev_down function is called.
 */
int nfc_dev_up(struct nfc_dev *dev)
{
        int rc = 0;

        pr_debug("dev_name=%s\n", dev_name(&dev->dev));

        device_lock(&dev->dev);

        if (dev->rfkill && rfkill_blocked(dev->rfkill)) {
                rc = -ERFKILL;
                goto error;
        }

        if (!device_is_registered(&dev->dev)) {
                rc = -ENODEV;
                goto error;
        }

        if (dev->fw_download_in_progress) {
                rc = -EBUSY;
                goto error;
        }

        if (dev->dev_up) {
                rc = -EALREADY;
                goto error;
        }

        if (dev->ops->dev_up)
                rc = dev->ops->dev_up(dev);

        if (!rc)
                dev->dev_up = true;

        /* We have to enable the device before discovering SEs */
        if (dev->ops->discover_se) {
                rc = dev->ops->discover_se(dev);
                if (rc)
                        pr_warn("SE discovery failed\n");
        }

error:
        device_unlock(&dev->dev);
        return rc;
}

/**
 * nfc_dev_down - turn off the NFC device
 *
 * @dev: The nfc device to be turned off
 */
int nfc_dev_down(struct nfc_dev *dev)
{
        int rc = 0;

        pr_debug("dev_name=%s\n", dev_name(&dev->dev));

        device_lock(&dev->dev);

        if (!device_is_registered(&dev->dev)) {
                rc = -ENODEV;
                goto error;
        }

        if (!dev->dev_up) {
                rc = -EALREADY;
                goto error;
        }

        if (dev->polling || dev->active_target) {
                rc = -EBUSY;
                goto error;
        }

        if (dev->ops->dev_down)
                dev->ops->dev_down(dev);

        dev->dev_up = false;

error:
        device_unlock(&dev->dev);
        return rc;
}

static int nfc_rfkill_set_block(void *data, bool blocked)
{
        struct nfc_dev *dev = data;

        pr_debug("%s blocked %d", dev_name(&dev->dev), blocked);

        if (!blocked)
                return 0;

        nfc_dev_down(dev);

        return 0;
}

static const struct rfkill_ops nfc_rfkill_ops = {
        .set_block = nfc_rfkill_set_block,
};

/**
 * nfc_start_poll - start polling for nfc targets
 *
 * @dev: The nfc device that must start polling
 * @protocols: bitset of nfc protocols that must be used for polling
 *
 * The device remains polling for targets until a target is found or
 * the nfc_stop_poll function is called.
 */
int nfc_start_poll(struct nfc_dev *dev, u32 im_protocols, u32 tm_protocols)
{
        int rc;

        pr_debug("dev_name %s initiator protocols 0x%x target protocols 0x%x\n",
                 dev_name(&dev->dev), im_protocols, tm_protocols);

        if (!im_protocols && !tm_protocols)
                return -EINVAL;

        device_lock(&dev->dev);

        if (!device_is_registered(&dev->dev)) {
                rc = -ENODEV;
                goto error;
        }

        if (!dev->dev_up) {
                rc = -ENODEV;
                goto error;
        }

        if (dev->polling) {
                rc = -EBUSY;
                goto error;
        }

        rc = dev->ops->start_poll(dev, im_protocols, tm_protocols);
        if (!rc) {
                dev->polling = true;
                dev->rf_mode = NFC_RF_NONE;
        }

error:
        device_unlock(&dev->dev);
        return rc;
}

/**
 * nfc_stop_poll - stop polling for nfc targets
 *
 * @dev: The nfc device that must stop polling
 */
int nfc_stop_poll(struct nfc_dev *dev)
{
        int rc = 0;

        pr_debug("dev_name=%s\n", dev_name(&dev->dev));

        device_lock(&dev->dev);

        if (!device_is_registered(&dev->dev)) {
                rc = -ENODEV;
                goto error;
        }

        if (!dev->polling) {
                rc = -EINVAL;
                goto error;
        }

        dev->ops->stop_poll(dev);
        dev->polling = false;
        dev->rf_mode = NFC_RF_NONE;

error:
        device_unlock(&dev->dev);
        return rc;
}

static struct nfc_target *nfc_find_target(struct nfc_dev *dev, u32 target_idx)
{
        int i;

        if (dev->n_targets == 0)
                return NULL;

        for (i = 0; i < dev->n_targets; i++) {
                if (dev->targets[i].idx == target_idx)
                        return &dev->targets[i];
        }

        return NULL;
}

int nfc_dep_link_up(struct nfc_dev *dev, int target_index, u8 comm_mode)
{
        int rc = 0;
        u8 *gb;
        size_t gb_len;
        struct nfc_target *target;

        pr_debug("dev_name=%s comm %d\n", dev_name(&dev->dev), comm_mode);

        if (!dev->ops->dep_link_up)
                return -EOPNOTSUPP;

        device_lock(&dev->dev);

        if (!device_is_registered(&dev->dev)) {
                rc = -ENODEV;
                goto error;
        }

        if (dev->dep_link_up == true) {
                rc = -EALREADY;
                goto error;
        }

        gb = nfc_llcp_general_bytes(dev, &gb_len);
        if (gb_len > NFC_MAX_GT_LEN) {
                rc = -EINVAL;
                goto error;
        }

        target = nfc_find_target(dev, target_index);
        if (target == NULL) {
                rc = -ENOTCONN;
                goto error;
        }

        rc = dev->ops->dep_link_up(dev, target, comm_mode, gb, gb_len);
        if (!rc) {
                dev->active_target = target;
                dev->rf_mode = NFC_RF_INITIATOR;
        }

error:
        device_unlock(&dev->dev);
        return rc;
}

int nfc_dep_link_down(struct nfc_dev *dev)
{
        int rc = 0;

        pr_debug("dev_name=%s\n", dev_name(&dev->dev));

        if (!dev->ops->dep_link_down)
                return -EOPNOTSUPP;

        device_lock(&dev->dev);

        if (!device_is_registered(&dev->dev)) {
                rc = -ENODEV;
                goto error;
        }

        if (dev->dep_link_up == false) {
                rc = -EALREADY;
                goto error;
        }

        rc = dev->ops->dep_link_down(dev);
        if (!rc) {
                dev->dep_link_up = false;
                dev->active_target = NULL;
                dev->rf_mode = NFC_RF_NONE;
                nfc_llcp_mac_is_down(dev);
                nfc_genl_dep_link_down_event(dev);
        }

error:
        device_unlock(&dev->dev);

        return rc;
}

int nfc_dep_link_is_up(struct nfc_dev *dev, u32 target_idx,
                       u8 comm_mode, u8 rf_mode)
{
        dev->dep_link_up = true;

        nfc_llcp_mac_is_up(dev, target_idx, comm_mode, rf_mode);

        return nfc_genl_dep_link_up_event(dev, target_idx, comm_mode, rf_mode);
}
EXPORT_SYMBOL(nfc_dep_link_is_up);

/**
 * nfc_activate_target - prepare the target for data exchange
 *
 * @dev: The nfc device that found the target
 * @target_idx: index of the target that must be activated
 * @protocol: nfc protocol that will be used for data exchange
 */
int nfc_activate_target(struct nfc_dev *dev, u32 target_idx, u32 protocol)
{
        int rc;
        struct nfc_target *target;

        pr_debug("dev_name=%s target_idx=%u protocol=%u\n",
                 dev_name(&dev->dev), target_idx, protocol);

        device_lock(&dev->dev);

        if (!device_is_registered(&dev->dev)) {
                rc = -ENODEV;
                goto error;
        }

        if (dev->active_target) {
                rc = -EBUSY;
                goto error;
        }

        target = nfc_find_target(dev, target_idx);
        if (target == NULL) {
                rc = -ENOTCONN;
                goto error;
        }

        rc = dev->ops->activate_target(dev, target, protocol);
        if (!rc) {
                dev->active_target = target;
                dev->rf_mode = NFC_RF_INITIATOR;

                if (dev->ops->check_presence && !dev->shutting_down)
                        mod_timer(&dev->check_pres_timer, jiffies +
                                  msecs_to_jiffies(NFC_CHECK_PRES_FREQ_MS));
        }

error:
        device_unlock(&dev->dev);
        return rc;
}

/**
 * nfc_deactivate_target - deactivate a nfc target
 *
 * @dev: The nfc device that found the target
 * @target_idx: index of the target that must be deactivated
 */
int nfc_deactivate_target(struct nfc_dev *dev, u32 target_idx)
{
        int rc = 0;

        pr_debug("dev_name=%s target_idx=%u\n",
                 dev_name(&dev->dev), target_idx);

        device_lock(&dev->dev);

        if (!device_is_registered(&dev->dev)) {
                rc = -ENODEV;
                goto error;
        }

        if (dev->active_target == NULL) {
                rc = -ENOTCONN;
                goto error;
        }

        if (dev->active_target->idx != target_idx) {
                rc = -ENOTCONN;
                goto error;
        }

        if (dev->ops->check_presence)
                del_timer_sync(&dev->check_pres_timer);

        dev->ops->deactivate_target(dev, dev->active_target);
        dev->active_target = NULL;

error:
        device_unlock(&dev->dev);
        return rc;
}

/**
 * nfc_data_exchange - transceive data
 *
 * @dev: The nfc device that found the target
 * @target_idx: index of the target
 * @skb: data to be sent
 * @cb: callback called when the response is received
 * @cb_context: parameter for the callback function
 *
 * The user must wait for the callback before calling this function again.
 */
int nfc_data_exchange(struct nfc_dev *dev, u32 target_idx, struct sk_buff *skb,
                      data_exchange_cb_t cb, void *cb_context)
{
        int rc;

        pr_debug("dev_name=%s target_idx=%u skb->len=%u\n",
                 dev_name(&dev->dev), target_idx, skb->len);

        device_lock(&dev->dev);

        if (!device_is_registered(&dev->dev)) {
                rc = -ENODEV;
                kfree_skb(skb);
                goto error;
        }

        if (dev->rf_mode == NFC_RF_INITIATOR && dev->active_target != NULL) {
                if (dev->active_target->idx != target_idx) {
                        rc = -EADDRNOTAVAIL;
                        kfree_skb(skb);
                        goto error;
                }

                if (dev->ops->check_presence)
                        del_timer_sync(&dev->check_pres_timer);

                rc = dev->ops->im_transceive(dev, dev->active_target, skb, cb,
                                             cb_context);

                if (!rc && dev->ops->check_presence && !dev->shutting_down)
                        mod_timer(&dev->check_pres_timer, jiffies +
                                  msecs_to_jiffies(NFC_CHECK_PRES_FREQ_MS));
        } else if (dev->rf_mode == NFC_RF_TARGET && dev->ops->tm_send != NULL) {
                rc = dev->ops->tm_send(dev, skb);
        } else {
                rc = -ENOTCONN;
                kfree_skb(skb);
                goto error;
        }


error:
        device_unlock(&dev->dev);
        return rc;
}

static struct nfc_se *find_se(struct nfc_dev *dev, u32 se_idx)
{
        struct nfc_se *se, *n;

        list_for_each_entry_safe(se, n, &dev->secure_elements, list)
                if (se->idx == se_idx)
                        return se;

        return NULL;
}

int nfc_enable_se(struct nfc_dev *dev, u32 se_idx)
{

        struct nfc_se *se;
        int rc;

        pr_debug("%s se index %d\n", dev_name(&dev->dev), se_idx);

        device_lock(&dev->dev);

        if (!device_is_registered(&dev->dev)) {
                rc = -ENODEV;
                goto error;
        }

        if (!dev->dev_up) {
                rc = -ENODEV;
                goto error;
        }

        if (dev->polling) {
                rc = -EBUSY;
                goto error;
        }

        if (!dev->ops->enable_se || !dev->ops->disable_se) {
                rc = -EOPNOTSUPP;
                goto error;
        }

        se = find_se(dev, se_idx);
        if (!se) {
                rc = -EINVAL;
                goto error;
        }

        if (se->state == NFC_SE_ENABLED) {
                rc = -EALREADY;
                goto error;
        }

        rc = dev->ops->enable_se(dev, se_idx);
        if (rc >= 0)
                se->state = NFC_SE_ENABLED;

error:
        device_unlock(&dev->dev);
        return rc;
}

int nfc_disable_se(struct nfc_dev *dev, u32 se_idx)
{

        struct nfc_se *se;
        int rc;

        pr_debug("%s se index %d\n", dev_name(&dev->dev), se_idx);

        device_lock(&dev->dev);

        if (!device_is_registered(&dev->dev)) {
                rc = -ENODEV;
                goto error;
        }

        if (!dev->dev_up) {
                rc = -ENODEV;
                goto error;
        }

        if (!dev->ops->enable_se || !dev->ops->disable_se) {
                rc = -EOPNOTSUPP;
                goto error;
        }

        se = find_se(dev, se_idx);
        if (!se) {
                rc = -EINVAL;
                goto error;
        }

        if (se->state == NFC_SE_DISABLED) {
                rc = -EALREADY;
                goto error;
        }

        rc = dev->ops->disable_se(dev, se_idx);
        if (rc >= 0)
                se->state = NFC_SE_DISABLED;

error:
        device_unlock(&dev->dev);
        return rc;
}

int nfc_set_remote_general_bytes(struct nfc_dev *dev, u8 *gb, u8 gb_len)
{
        pr_debug("dev_name=%s gb_len=%d\n", dev_name(&dev->dev), gb_len);

        if (gb_len > NFC_MAX_GT_LEN)
                return -EINVAL;

        return nfc_llcp_set_remote_gb(dev, gb, gb_len);
}
EXPORT_SYMBOL(nfc_set_remote_general_bytes);

u8 *nfc_get_local_general_bytes(struct nfc_dev *dev, size_t *gb_len)
{
        pr_debug("dev_name=%s\n", dev_name(&dev->dev));

        return nfc_llcp_general_bytes(dev, gb_len);
}
EXPORT_SYMBOL(nfc_get_local_general_bytes);

int nfc_tm_data_received(struct nfc_dev *dev, struct sk_buff *skb)
{
        /* Only LLCP target mode for now */
        if (dev->dep_link_up == false) {
                kfree_skb(skb);
                return -ENOLINK;
        }

        return nfc_llcp_data_received(dev, skb);
}
EXPORT_SYMBOL(nfc_tm_data_received);

int nfc_tm_activated(struct nfc_dev *dev, u32 protocol, u8 comm_mode,
                     u8 *gb, size_t gb_len)
{
        int rc;

        device_lock(&dev->dev);

        dev->polling = false;

        if (gb != NULL) {
                rc = nfc_set_remote_general_bytes(dev, gb, gb_len);
                if (rc < 0)
                        goto out;
        }

        dev->rf_mode = NFC_RF_TARGET;

        if (protocol == NFC_PROTO_NFC_DEP_MASK)
                nfc_dep_link_is_up(dev, 0, comm_mode, NFC_RF_TARGET);

        rc = nfc_genl_tm_activated(dev, protocol);

out:
        device_unlock(&dev->dev);

        return rc;
}
EXPORT_SYMBOL(nfc_tm_activated);

int nfc_tm_deactivated(struct nfc_dev *dev)
{
        dev->dep_link_up = false;
        dev->rf_mode = NFC_RF_NONE;

        return nfc_genl_tm_deactivated(dev);
}
EXPORT_SYMBOL(nfc_tm_deactivated);

/**
 * nfc_alloc_send_skb - allocate a skb for data exchange responses
 *
 * @size: size to allocate
 * @gfp: gfp flags
 */
struct sk_buff *nfc_alloc_send_skb(struct nfc_dev *dev, struct sock *sk,
                                   unsigned int flags, unsigned int size,
                                   unsigned int *err)
{
        struct sk_buff *skb;
        unsigned int total_size;

        total_size = size +
                dev->tx_headroom + dev->tx_tailroom + NFC_HEADER_SIZE;

        skb = sock_alloc_send_skb(sk, total_size, flags & MSG_DONTWAIT, err);
        if (skb)
                skb_reserve(skb, dev->tx_headroom + NFC_HEADER_SIZE);

        return skb;
}

/**
 * nfc_alloc_recv_skb - allocate a skb for data exchange responses
 *
 * @size: size to allocate
 * @gfp: gfp flags
 */
struct sk_buff *nfc_alloc_recv_skb(unsigned int size, gfp_t gfp)
{
        struct sk_buff *skb;
        unsigned int total_size;

        total_size = size + 1;
        skb = alloc_skb(total_size, gfp);

        if (skb)
                skb_reserve(skb, 1);

        return skb;
}
EXPORT_SYMBOL(nfc_alloc_recv_skb);

/**
 * nfc_targets_found - inform that targets were found
 *
 * @dev: The nfc device that found the targets
 * @targets: array of nfc targets found
 * @ntargets: targets array size
 *
 * The device driver must call this function when one or many nfc targets
 * are found. After calling this function, the device driver must stop
 * polling for targets.
 * NOTE: This function can be called with targets=NULL and n_targets=0 to
 * notify a driver error, meaning that the polling operation cannot complete.
 * IMPORTANT: this function must not be called from an atomic context.
 * In addition, it must also not be called from a context that would prevent
 * the NFC Core to call other nfc ops entry point concurrently.
 */
int nfc_targets_found(struct nfc_dev *dev,
                      struct nfc_target *targets, int n_targets)
{
        int i;

        pr_debug("dev_name=%s n_targets=%d\n", dev_name(&dev->dev), n_targets);

        for (i = 0; i < n_targets; i++)
                targets[i].idx = dev->target_next_idx++;

        device_lock(&dev->dev);

        if (dev->polling == false) {
                device_unlock(&dev->dev);
                return 0;
        }

        dev->polling = false;

        dev->targets_generation++;

        kfree(dev->targets);
        dev->targets = NULL;

        if (targets) {
                dev->targets = kmemdup(targets,
                                       n_targets * sizeof(struct nfc_target),
                                       GFP_ATOMIC);

                if (!dev->targets) {
                        dev->n_targets = 0;
                        device_unlock(&dev->dev);
                        return -ENOMEM;
                }
        }

        dev->n_targets = n_targets;
        device_unlock(&dev->dev);

        nfc_genl_targets_found(dev);

        return 0;
}
EXPORT_SYMBOL(nfc_targets_found);

/**
 * nfc_target_lost - inform that an activated target went out of field
 *
 * @dev: The nfc device that had the activated target in field
 * @target_idx: the nfc index of the target
 *
 * The device driver must call this function when the activated target
 * goes out of the field.
 * IMPORTANT: this function must not be called from an atomic context.
 * In addition, it must also not be called from a context that would prevent
 * the NFC Core to call other nfc ops entry point concurrently.
 */
int nfc_target_lost(struct nfc_dev *dev, u32 target_idx)
{
        struct nfc_target *tg;
        int i;

        pr_debug("dev_name %s n_target %d\n", dev_name(&dev->dev), target_idx);

        device_lock(&dev->dev);

        for (i = 0; i < dev->n_targets; i++) {
                tg = &dev->targets[i];
                if (tg->idx == target_idx)
                        break;
        }

        if (i == dev->n_targets) {
                device_unlock(&dev->dev);
                return -EINVAL;
        }

        dev->targets_generation++;
        dev->n_targets--;
        dev->active_target = NULL;

        if (dev->n_targets) {
                memcpy(&dev->targets[i], &dev->targets[i + 1],
                       (dev->n_targets - i) * sizeof(struct nfc_target));
        } else {
                kfree(dev->targets);
                dev->targets = NULL;
        }

        device_unlock(&dev->dev);

        nfc_genl_target_lost(dev, target_idx);

        return 0;
}
EXPORT_SYMBOL(nfc_target_lost);

inline void nfc_driver_failure(struct nfc_dev *dev, int err)
{
        nfc_targets_found(dev, NULL, 0);
}
EXPORT_SYMBOL(nfc_driver_failure);

int nfc_add_se(struct nfc_dev *dev, u32 se_idx, u16 type)
{
        struct nfc_se *se;
        int rc;

        pr_debug("%s se index %d\n", dev_name(&dev->dev), se_idx);

        se = find_se(dev, se_idx);
        if (se)
                return -EALREADY;

        se = kzalloc(sizeof(struct nfc_se), GFP_KERNEL);
        if (!se)
                return -ENOMEM;

        se->idx = se_idx;
        se->type = type;
        se->state = NFC_SE_DISABLED;
        INIT_LIST_HEAD(&se->list);

        list_add(&se->list, &dev->secure_elements);

        rc = nfc_genl_se_added(dev, se_idx, type);
        if (rc < 0) {
                list_del(&se->list);
                kfree(se);

                return rc;
        }

        return 0;
}
EXPORT_SYMBOL(nfc_add_se);

int nfc_remove_se(struct nfc_dev *dev, u32 se_idx)
{
        struct nfc_se *se, *n;
        int rc;

        pr_debug("%s se index %d\n", dev_name(&dev->dev), se_idx);

        list_for_each_entry_safe(se, n, &dev->secure_elements, list)
                if (se->idx == se_idx) {
                        rc = nfc_genl_se_removed(dev, se_idx);
                        if (rc < 0)
                                return rc;

                        list_del(&se->list);
                        kfree(se);

                        return 0;
                }

        return -EINVAL;
}
EXPORT_SYMBOL(nfc_remove_se);

static void nfc_release(struct device *d)
{
        struct nfc_dev *dev = to_nfc_dev(d);
        struct nfc_se *se, *n;

        pr_debug("dev_name=%s\n", dev_name(&dev->dev));

        nfc_genl_data_exit(&dev->genl_data);
        kfree(dev->targets);

        list_for_each_entry_safe(se, n, &dev->secure_elements, list) {
                        nfc_genl_se_removed(dev, se->idx);
                        list_del(&se->list);
                        kfree(se);
        }

        kfree(dev);
}

static void nfc_check_pres_work(struct work_struct *work)
{
        struct nfc_dev *dev = container_of(work, struct nfc_dev,
                                           check_pres_work);
        int rc;

        device_lock(&dev->dev);

        if (dev->active_target && timer_pending(&dev->check_pres_timer) == 0) {
                rc = dev->ops->check_presence(dev, dev->active_target);
                if (rc == -EOPNOTSUPP)
                        goto exit;
                if (rc) {
                        u32 active_target_idx = dev->active_target->idx;
                        device_unlock(&dev->dev);
                        nfc_target_lost(dev, active_target_idx);
                        return;
                }

                if (!dev->shutting_down)
                        mod_timer(&dev->check_pres_timer, jiffies +
                                  msecs_to_jiffies(NFC_CHECK_PRES_FREQ_MS));
        }

exit:
        device_unlock(&dev->dev);
}

static void nfc_check_pres_timeout(unsigned long data)
{
        struct nfc_dev *dev = (struct nfc_dev *)data;

        schedule_work(&dev->check_pres_work);
}

struct class nfc_class = {
        .name = "nfc",
        .dev_release = nfc_release,
};
EXPORT_SYMBOL(nfc_class);

static int match_idx(struct device *d, const void *data)
{
        struct nfc_dev *dev = to_nfc_dev(d);
        const unsigned int *idx = data;

        return dev->idx == *idx;
}

struct nfc_dev *nfc_get_device(unsigned int idx)
{
        struct device *d;

        d = class_find_device(&nfc_class, NULL, &idx, match_idx);
        if (!d)
                return NULL;

        return to_nfc_dev(d);
}

/**
 * nfc_allocate_device - allocate a new nfc device
 *
 * @ops: device operations
 * @supported_protocols: NFC protocols supported by the device
 */
struct nfc_dev *nfc_allocate_device(struct nfc_ops *ops,
                                    u32 supported_protocols,
                                    int tx_headroom, int tx_tailroom)
{
        struct nfc_dev *dev;

        if (!ops->start_poll || !ops->stop_poll || !ops->activate_target ||
            !ops->deactivate_target || !ops->im_transceive)
                return NULL;

        if (!supported_protocols)
                return NULL;

        dev = kzalloc(sizeof(struct nfc_dev), GFP_KERNEL);
        if (!dev)
                return NULL;

        dev->ops = ops;
        dev->supported_protocols = supported_protocols;
        dev->tx_headroom = tx_headroom;
        dev->tx_tailroom = tx_tailroom;
        INIT_LIST_HEAD(&dev->secure_elements);

        nfc_genl_data_init(&dev->genl_data);

        dev->rf_mode = NFC_RF_NONE;

        /* first generation must not be 0 */
        dev->targets_generation = 1;

        if (ops->check_presence) {
                init_timer(&dev->check_pres_timer);
                dev->check_pres_timer.data = (unsigned long)dev;
                dev->check_pres_timer.function = nfc_check_pres_timeout;

                INIT_WORK(&dev->check_pres_work, nfc_check_pres_work);
        }

        return dev;
}
EXPORT_SYMBOL(nfc_allocate_device);

/**
 * nfc_register_device - register a nfc device in the nfc subsystem
 *
 * @dev: The nfc device to register
 */
int nfc_register_device(struct nfc_dev *dev)
{
        int rc;

        pr_debug("dev_name=%s\n", dev_name(&dev->dev));

        dev->idx = ida_simple_get(&nfc_index_ida, 0, 0, GFP_KERNEL);
        if (dev->idx < 0)
                return dev->idx;

        dev->dev.class = &nfc_class;
        dev_set_name(&dev->dev, "nfc%d", dev->idx);
        device_initialize(&dev->dev);

        mutex_lock(&nfc_devlist_mutex);
        nfc_devlist_generation++;
        rc = device_add(&dev->dev);
        mutex_unlock(&nfc_devlist_mutex);

        if (rc < 0)
                return rc;

        rc = nfc_llcp_register_device(dev);
        if (rc)
                pr_err("Could not register llcp device\n");

        rc = nfc_genl_device_added(dev);
        if (rc)
                pr_debug("The userspace won't be notified that the device %s was added\n",
                         dev_name(&dev->dev));

        dev->rfkill = rfkill_alloc(dev_name(&dev->dev), &dev->dev,
                                   RFKILL_TYPE_NFC, &nfc_rfkill_ops, dev);
        if (dev->rfkill) {
                if (rfkill_register(dev->rfkill) < 0) {
                        rfkill_destroy(dev->rfkill);
                        dev->rfkill = NULL;
                }
        }

        return 0;
}
EXPORT_SYMBOL(nfc_register_device);

/**
 * nfc_unregister_device - unregister a nfc device in the nfc subsystem
 *
 * @dev: The nfc device to unregister
 */
void nfc_unregister_device(struct nfc_dev *dev)
{
        int rc, id;

        pr_debug("dev_name=%s\n", dev_name(&dev->dev));

        id = dev->idx;

        if (dev->rfkill) {
                rfkill_unregister(dev->rfkill);
                rfkill_destroy(dev->rfkill);
        }

        if (dev->ops->check_presence) {
                device_lock(&dev->dev);
                dev->shutting_down = true;
                device_unlock(&dev->dev);
                del_timer_sync(&dev->check_pres_timer);
                cancel_work_sync(&dev->check_pres_work);
        }

        rc = nfc_genl_device_removed(dev);
        if (rc)
                pr_debug("The userspace won't be notified that the device %s "
                         "was removed\n", dev_name(&dev->dev));

        nfc_llcp_unregister_device(dev);

        mutex_lock(&nfc_devlist_mutex);
        nfc_devlist_generation++;
        device_del(&dev->dev);
        mutex_unlock(&nfc_devlist_mutex);

        ida_simple_remove(&nfc_index_ida, id);
}
EXPORT_SYMBOL(nfc_unregister_device);

static int __init nfc_init(void)
{
        int rc;

        pr_info("NFC Core ver %s\n", VERSION);

        rc = class_register(&nfc_class);
        if (rc)
                return rc;

        rc = nfc_genl_init();
        if (rc)
                goto err_genl;

        /* the first generation must not be 0 */
        nfc_devlist_generation = 1;

        rc = rawsock_init();
        if (rc)
                goto err_rawsock;

        rc = nfc_llcp_init();
        if (rc)
                goto err_llcp_sock;

        rc = af_nfc_init();
        if (rc)
                goto err_af_nfc;

        return 0;

err_af_nfc:
        nfc_llcp_exit();
err_llcp_sock:
        rawsock_exit();
err_rawsock:
        nfc_genl_exit();
err_genl:
        class_unregister(&nfc_class);
        return rc;
}

static void __exit nfc_exit(void)
{
        af_nfc_exit();
        nfc_llcp_exit();
        rawsock_exit();
        nfc_genl_exit();
        class_unregister(&nfc_class);
}

subsys_initcall(nfc_init);
module_exit(nfc_exit);

MODULE_AUTHOR("Lauro Ramos Venancio <lauro.venancio@openbossa.org>");
MODULE_DESCRIPTION("NFC Core ver " VERSION);
MODULE_VERSION(VERSION);
MODULE_LICENSE("GPL");
MODULE_ALIAS_NETPROTO(PF_NFC);
MODULE_ALIAS_GENL_FAMILY(NFC_GENL_NAME);