core.c

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/*
 *  The NFC Controller Interface is the communication protocol between an
 *  NFC Controller (NFCC) and a Device Host (DH).
 *
 *  Copyright (C) 2011 Texas Instruments, Inc.
 *
 *  Written by Ilan Elias <[email protected]>
 *
 *  Acknowledgements:
 *  This file is based on hci_core.c, which was written
 *  by Maxim Krasnyansky.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2
 *  as published by the Free Software Foundation
 *
 *  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/module.h>
#include <linux/types.h>
#include <linux/workqueue.h>
#include <linux/completion.h>
#include <linux/export.h>
#include <linux/sched.h>
#include <linux/bitops.h>
#include <linux/skbuff.h>

#include "../nfc.h"
#include <net/nfc/nci.h>
#include <net/nfc/nci_core.h>
#include <linux/nfc.h>

static void nci_cmd_work(struct work_struct *work);
static void nci_rx_work(struct work_struct *work);
static void nci_tx_work(struct work_struct *work);

/* ---- NCI requests ---- */

void nci_req_complete(struct nci_dev *ndev, int result)
{
    if (ndev->req_status == NCI_REQ_PEND) {
        ndev->req_result = result;
        ndev->req_status = NCI_REQ_DONE;
        complete(&ndev->req_completion);
    }
}

static void nci_req_cancel(struct nci_dev *ndev, int err)
{
    if (ndev->req_status == NCI_REQ_PEND) {
        ndev->req_result = err;
        ndev->req_status = NCI_REQ_CANCELED;
        complete(&ndev->req_completion);
    }
}

/* Execute request and wait for completion. */
static int __nci_request(struct nci_dev *ndev,
             void (*req)(struct nci_dev *ndev, unsigned long opt),
             unsigned long opt, __u32 timeout)
{
    int rc = 0;
    long completion_rc;

    ndev->req_status = NCI_REQ_PEND;

    init_completion(&ndev->req_completion);
    req(ndev, opt);
    completion_rc =
        wait_for_completion_interruptible_timeout(&ndev->req_completion,
                              timeout);

    pr_debug("wait_for_completion return %ld\n", completion_rc);

    if (completion_rc > 0) {
        switch (ndev->req_status) {
        case NCI_REQ_DONE:
            rc = nci_to_errno(ndev->req_result);
            break;

        case NCI_REQ_CANCELED:
            rc = -ndev->req_result;
            break;

        default:
            rc = -ETIMEDOUT;
            break;
        }
    } else {
        pr_err("wait_for_completion_interruptible_timeout failed %ld\n",
               completion_rc);

        rc = ((completion_rc == 0) ? (-ETIMEDOUT) : (completion_rc));
    }

    ndev->req_status = ndev->req_result = 0;

    return rc;
}

static inline int nci_request(struct nci_dev *ndev,
                  void (*req)(struct nci_dev *ndev,
                      unsigned long opt),
                  unsigned long opt, __u32 timeout)
{
    int rc;

    if (!test_bit(NCI_UP, &ndev->flags))
        return -ENETDOWN;

    /* Serialize all requests */
    mutex_lock(&ndev->req_lock);
    rc = __nci_request(ndev, req, opt, timeout);
    mutex_unlock(&ndev->req_lock);

    return rc;
}

static void nci_reset_req(struct nci_dev *ndev, unsigned long opt)
{
    struct nci_core_reset_cmd cmd;

    cmd.reset_type = NCI_RESET_TYPE_RESET_CONFIG;
    nci_send_cmd(ndev, NCI_OP_CORE_RESET_CMD, 1, &cmd);
}

static void nci_init_req(struct nci_dev *ndev, unsigned long opt)
{
    nci_send_cmd(ndev, NCI_OP_CORE_INIT_CMD, 0, NULL);
}

static void nci_init_complete_req(struct nci_dev *ndev, unsigned long opt)
{
    struct nci_rf_disc_map_cmd cmd;
    struct disc_map_config *cfg = cmd.mapping_configs;
    __u8 *num = &cmd.num_mapping_configs;
    int i;

    /* set rf mapping configurations */
    *num = 0;

    /* by default mapping is set to NCI_RF_INTERFACE_FRAME */
    for (i = 0; i < ndev->num_supported_rf_interfaces; i++) {
        if (ndev->supported_rf_interfaces[i] ==
            NCI_RF_INTERFACE_ISO_DEP) {
            cfg[*num].rf_protocol = NCI_RF_PROTOCOL_ISO_DEP;
            cfg[*num].mode = NCI_DISC_MAP_MODE_POLL |
                NCI_DISC_MAP_MODE_LISTEN;
            cfg[*num].rf_interface = NCI_RF_INTERFACE_ISO_DEP;
            (*num)++;
        } else if (ndev->supported_rf_interfaces[i] ==
               NCI_RF_INTERFACE_NFC_DEP) {
            cfg[*num].rf_protocol = NCI_RF_PROTOCOL_NFC_DEP;
            cfg[*num].mode = NCI_DISC_MAP_MODE_POLL |
                NCI_DISC_MAP_MODE_LISTEN;
            cfg[*num].rf_interface = NCI_RF_INTERFACE_NFC_DEP;
            (*num)++;
        }

        if (*num == NCI_MAX_NUM_MAPPING_CONFIGS)
            break;
    }

    nci_send_cmd(ndev, NCI_OP_RF_DISCOVER_MAP_CMD,
             (1 + ((*num) * sizeof(struct disc_map_config))), &cmd);
}

struct nci_set_config_param {
    __u8    id;
    size_t  len;
    __u8    *val;
};

static void nci_set_config_req(struct nci_dev *ndev, unsigned long opt)
{
    struct nci_set_config_param *param = (struct nci_set_config_param *)opt;
    struct nci_core_set_config_cmd cmd;

    BUG_ON(param->len > NCI_MAX_PARAM_LEN);

    cmd.num_params = 1;
    cmd.param.id = param->id;
    cmd.param.len = param->len;
    memcpy(cmd.param.val, param->val, param->len);

    nci_send_cmd(ndev, NCI_OP_CORE_SET_CONFIG_CMD, (3 + param->len), &cmd);
}

static void nci_rf_discover_req(struct nci_dev *ndev, unsigned long opt)
{
    struct nci_rf_disc_cmd cmd;
    __u32 protocols = opt;

    cmd.num_disc_configs = 0;

    if ((cmd.num_disc_configs < NCI_MAX_NUM_RF_CONFIGS) &&
        (protocols & NFC_PROTO_JEWEL_MASK
         || protocols & NFC_PROTO_MIFARE_MASK
         || protocols & NFC_PROTO_ISO14443_MASK
         || protocols & NFC_PROTO_NFC_DEP_MASK)) {
        cmd.disc_configs[cmd.num_disc_configs].rf_tech_and_mode =
            NCI_NFC_A_PASSIVE_POLL_MODE;
        cmd.disc_configs[cmd.num_disc_configs].frequency = 1;
        cmd.num_disc_configs++;
    }

    if ((cmd.num_disc_configs < NCI_MAX_NUM_RF_CONFIGS) &&
        (protocols & NFC_PROTO_ISO14443_B_MASK)) {
        cmd.disc_configs[cmd.num_disc_configs].rf_tech_and_mode =
            NCI_NFC_B_PASSIVE_POLL_MODE;
        cmd.disc_configs[cmd.num_disc_configs].frequency = 1;
        cmd.num_disc_configs++;
    }

    if ((cmd.num_disc_configs < NCI_MAX_NUM_RF_CONFIGS) &&
        (protocols & NFC_PROTO_FELICA_MASK
         || protocols & NFC_PROTO_NFC_DEP_MASK)) {
        cmd.disc_configs[cmd.num_disc_configs].rf_tech_and_mode =
            NCI_NFC_F_PASSIVE_POLL_MODE;
        cmd.disc_configs[cmd.num_disc_configs].frequency = 1;
        cmd.num_disc_configs++;
    }

    nci_send_cmd(ndev, NCI_OP_RF_DISCOVER_CMD,
             (1 + (cmd.num_disc_configs * sizeof(struct disc_config))),
             &cmd);
}

struct nci_rf_discover_select_param {
    __u8    rf_discovery_id;
    __u8    rf_protocol;
};

static void nci_rf_discover_select_req(struct nci_dev *ndev, unsigned long opt)
{
    struct nci_rf_discover_select_param *param =
        (struct nci_rf_discover_select_param *)opt;
    struct nci_rf_discover_select_cmd cmd;

    cmd.rf_discovery_id = param->rf_discovery_id;
    cmd.rf_protocol = param->rf_protocol;

    switch (cmd.rf_protocol) {
    case NCI_RF_PROTOCOL_ISO_DEP:
        cmd.rf_interface = NCI_RF_INTERFACE_ISO_DEP;
        break;

    case NCI_RF_PROTOCOL_NFC_DEP:
        cmd.rf_interface = NCI_RF_INTERFACE_NFC_DEP;
        break;

    default:
        cmd.rf_interface = NCI_RF_INTERFACE_FRAME;
        break;
    }

    nci_send_cmd(ndev, NCI_OP_RF_DISCOVER_SELECT_CMD,
             sizeof(struct nci_rf_discover_select_cmd), &cmd);
}

static void nci_rf_deactivate_req(struct nci_dev *ndev, unsigned long opt)
{
    struct nci_rf_deactivate_cmd cmd;

    cmd.type = NCI_DEACTIVATE_TYPE_IDLE_MODE;

    nci_send_cmd(ndev, NCI_OP_RF_DEACTIVATE_CMD,
             sizeof(struct nci_rf_deactivate_cmd), &cmd);
}

static int nci_open_device(struct nci_dev *ndev)
{
    int rc = 0;

    mutex_lock(&ndev->req_lock);

    if (test_bit(NCI_UP, &ndev->flags)) {
        rc = -EALREADY;
        goto done;
    }

    if (ndev->ops->open(ndev)) {
        rc = -EIO;
        goto done;
    }

    atomic_set(&ndev->cmd_cnt, 1);

    set_bit(NCI_INIT, &ndev->flags);

    rc = __nci_request(ndev, nci_reset_req, 0,
               msecs_to_jiffies(NCI_RESET_TIMEOUT));

    if (!rc) {
        rc = __nci_request(ndev, nci_init_req, 0,
                   msecs_to_jiffies(NCI_INIT_TIMEOUT));
    }

    if (!rc) {
        rc = __nci_request(ndev, nci_init_complete_req, 0,
                   msecs_to_jiffies(NCI_INIT_TIMEOUT));
    }

    clear_bit(NCI_INIT, &ndev->flags);

    if (!rc) {
        set_bit(NCI_UP, &ndev->flags);
        nci_clear_target_list(ndev);
        atomic_set(&ndev->state, NCI_IDLE);
    } else {
        /* Init failed, cleanup */
        skb_queue_purge(&ndev->cmd_q);
        skb_queue_purge(&ndev->rx_q);
        skb_queue_purge(&ndev->tx_q);

        ndev->ops->close(ndev);
        ndev->flags = 0;
    }

done:
    mutex_unlock(&ndev->req_lock);
    return rc;
}

static int nci_close_device(struct nci_dev *ndev)
{
    nci_req_cancel(ndev, ENODEV);
    mutex_lock(&ndev->req_lock);

    if (!test_and_clear_bit(NCI_UP, &ndev->flags)) {
        del_timer_sync(&ndev->cmd_timer);
        del_timer_sync(&ndev->data_timer);
        mutex_unlock(&ndev->req_lock);
        return 0;
    }

    /* Drop RX and TX queues */
    skb_queue_purge(&ndev->rx_q);
    skb_queue_purge(&ndev->tx_q);

    /* Flush RX and TX wq */
    flush_workqueue(ndev->rx_wq);
    flush_workqueue(ndev->tx_wq);

    /* Reset device */
    skb_queue_purge(&ndev->cmd_q);
    atomic_set(&ndev->cmd_cnt, 1);

    set_bit(NCI_INIT, &ndev->flags);
    __nci_request(ndev, nci_reset_req, 0,
              msecs_to_jiffies(NCI_RESET_TIMEOUT));
    clear_bit(NCI_INIT, &ndev->flags);

    /* Flush cmd wq */
    flush_workqueue(ndev->cmd_wq);

    /* After this point our queues are empty
     * and no works are scheduled. */
    ndev->ops->close(ndev);

    /* Clear flags */
    ndev->flags = 0;

    mutex_unlock(&ndev->req_lock);

    return 0;
}

/* NCI command timer function */
static void nci_cmd_timer(unsigned long arg)
{
    struct nci_dev *ndev = (void *) arg;

    atomic_set(&ndev->cmd_cnt, 1);
    queue_work(ndev->cmd_wq, &ndev->cmd_work);
}

/* NCI data exchange timer function */
static void nci_data_timer(unsigned long arg)
{
    struct nci_dev *ndev = (void *) arg;

    set_bit(NCI_DATA_EXCHANGE_TO, &ndev->flags);
    queue_work(ndev->rx_wq, &ndev->rx_work);
}

static int nci_dev_up(struct nfc_dev *nfc_dev)
{
    struct nci_dev *ndev = nfc_get_drvdata(nfc_dev);

    return nci_open_device(ndev);
}

static int nci_dev_down(struct nfc_dev *nfc_dev)
{
    struct nci_dev *ndev = nfc_get_drvdata(nfc_dev);

    return nci_close_device(ndev);
}

static int nci_set_local_general_bytes(struct nfc_dev *nfc_dev)
{
    struct nci_dev *ndev = nfc_get_drvdata(nfc_dev);
    struct nci_set_config_param param;
    __u8 local_gb[NFC_MAX_GT_LEN];
    int i, rc = 0;

    param.val = nfc_get_local_general_bytes(nfc_dev, &param.len);
    if ((param.val == NULL) || (param.len == 0))
        return rc;

    if (param.len > NCI_MAX_PARAM_LEN)
        return -EINVAL;

    for (i = 0; i < param.len; i++)
        local_gb[param.len-1-i] = param.val[i];

    param.id = NCI_PN_ATR_REQ_GEN_BYTES;
    param.val = local_gb;

    rc = nci_request(ndev, nci_set_config_req, (unsigned long)&param,
             msecs_to_jiffies(NCI_SET_CONFIG_TIMEOUT));

    return rc;
}

static int nci_start_poll(struct nfc_dev *nfc_dev,
              __u32 im_protocols, __u32 tm_protocols)
{
    struct nci_dev *ndev = nfc_get_drvdata(nfc_dev);
    int rc;

    if ((atomic_read(&ndev->state) == NCI_DISCOVERY) ||
        (atomic_read(&ndev->state) == NCI_W4_ALL_DISCOVERIES)) {
        pr_err("unable to start poll, since poll is already active\n");
        return -EBUSY;
    }

    if (ndev->target_active_prot) {
        pr_err("there is an active target\n");
        return -EBUSY;
    }

    if ((atomic_read(&ndev->state) == NCI_W4_HOST_SELECT) ||
        (atomic_read(&ndev->state) == NCI_POLL_ACTIVE)) {
        pr_debug("target active or w4 select, implicitly deactivate\n");

        rc = nci_request(ndev, nci_rf_deactivate_req, 0,
                 msecs_to_jiffies(NCI_RF_DEACTIVATE_TIMEOUT));
        if (rc)
            return -EBUSY;
    }

    if (im_protocols & NFC_PROTO_NFC_DEP_MASK) {
        rc = nci_set_local_general_bytes(nfc_dev);
        if (rc) {
            pr_err("failed to set local general bytes\n");
            return rc;
        }
    }

    rc = nci_request(ndev, nci_rf_discover_req, im_protocols,
             msecs_to_jiffies(NCI_RF_DISC_TIMEOUT));

    if (!rc)
        ndev->poll_prots = im_protocols;

    return rc;
}

static void nci_stop_poll(struct nfc_dev *nfc_dev)
{
    struct nci_dev *ndev = nfc_get_drvdata(nfc_dev);

    if ((atomic_read(&ndev->state) != NCI_DISCOVERY) &&
        (atomic_read(&ndev->state) != NCI_W4_ALL_DISCOVERIES)) {
        pr_err("unable to stop poll, since poll is not active\n");
        return;
    }

    nci_request(ndev, nci_rf_deactivate_req, 0,
            msecs_to_jiffies(NCI_RF_DEACTIVATE_TIMEOUT));
}

static int nci_activate_target(struct nfc_dev *nfc_dev,
                   struct nfc_target *target, __u32 protocol)
{
    struct nci_dev *ndev = nfc_get_drvdata(nfc_dev);
    struct nci_rf_discover_select_param param;
    struct nfc_target *nci_target = NULL;
    int i;
    int rc = 0;

    pr_debug("target_idx %d, protocol 0x%x\n", target->idx, protocol);

    if ((atomic_read(&ndev->state) != NCI_W4_HOST_SELECT) &&
        (atomic_read(&ndev->state) != NCI_POLL_ACTIVE)) {
        pr_err("there is no available target to activate\n");
        return -EINVAL;
    }

    if (ndev->target_active_prot) {
        pr_err("there is already an active target\n");
        return -EBUSY;
    }

    for (i = 0; i < ndev->n_targets; i++) {
        if (ndev->targets[i].idx == target->idx) {
            nci_target = &ndev->targets[i];
            break;
        }
    }

    if (!nci_target) {
        pr_err("unable to find the selected target\n");
        return -EINVAL;
    }

    if (!(nci_target->supported_protocols & (1 << protocol))) {
        pr_err("target does not support the requested protocol 0x%x\n",
               protocol);
        return -EINVAL;
    }

    if (atomic_read(&ndev->state) == NCI_W4_HOST_SELECT) {
        param.rf_discovery_id = nci_target->logical_idx;

        if (protocol == NFC_PROTO_JEWEL)
            param.rf_protocol = NCI_RF_PROTOCOL_T1T;
        else if (protocol == NFC_PROTO_MIFARE)
            param.rf_protocol = NCI_RF_PROTOCOL_T2T;
        else if (protocol == NFC_PROTO_FELICA)
            param.rf_protocol = NCI_RF_PROTOCOL_T3T;
        else if (protocol == NFC_PROTO_ISO14443 ||
             protocol == NFC_PROTO_ISO14443_B)
            param.rf_protocol = NCI_RF_PROTOCOL_ISO_DEP;
        else
            param.rf_protocol = NCI_RF_PROTOCOL_NFC_DEP;

        rc = nci_request(ndev, nci_rf_discover_select_req,
                 (unsigned long)&param,
                 msecs_to_jiffies(NCI_RF_DISC_SELECT_TIMEOUT));
    }

    if (!rc)
        ndev->target_active_prot = protocol;

    return rc;
}

static void nci_deactivate_target(struct nfc_dev *nfc_dev,
                  struct nfc_target *target)
{
    struct nci_dev *ndev = nfc_get_drvdata(nfc_dev);

    pr_debug("entry\n");

    if (!ndev->target_active_prot) {
        pr_err("unable to deactivate target, no active target\n");
        return;
    }

    ndev->target_active_prot = 0;

    if (atomic_read(&ndev->state) == NCI_POLL_ACTIVE) {
        nci_request(ndev, nci_rf_deactivate_req, 0,
                msecs_to_jiffies(NCI_RF_DEACTIVATE_TIMEOUT));
    }
}


static int nci_dep_link_up(struct nfc_dev *nfc_dev, struct nfc_target *target,
               __u8 comm_mode, __u8 *gb, size_t gb_len)
{
    struct nci_dev *ndev = nfc_get_drvdata(nfc_dev);
    int rc;

    pr_debug("target_idx %d, comm_mode %d\n", target->idx, comm_mode);

    rc = nci_activate_target(nfc_dev, target, NFC_PROTO_NFC_DEP);
    if (rc)
        return rc;

    rc = nfc_set_remote_general_bytes(nfc_dev, ndev->remote_gb,
                      ndev->remote_gb_len);
    if (!rc)
        rc = nfc_dep_link_is_up(nfc_dev, target->idx, NFC_COMM_PASSIVE,
                    NFC_RF_INITIATOR);

    return rc;
}

static int nci_dep_link_down(struct nfc_dev *nfc_dev)
{
    pr_debug("entry\n");

    nci_deactivate_target(nfc_dev, NULL);

    return 0;
}


static int nci_transceive(struct nfc_dev *nfc_dev, struct nfc_target *target,
              struct sk_buff *skb,
              data_exchange_cb_t cb, void *cb_context)
{
    struct nci_dev *ndev = nfc_get_drvdata(nfc_dev);
    int rc;

    pr_debug("target_idx %d, len %d\n", target->idx, skb->len);

    if (!ndev->target_active_prot) {
        pr_err("unable to exchange data, no active target\n");
        return -EINVAL;
    }

    if (test_and_set_bit(NCI_DATA_EXCHANGE, &ndev->flags))
        return -EBUSY;

    /* store cb and context to be used on receiving data */
    ndev->data_exchange_cb = cb;
    ndev->data_exchange_cb_context = cb_context;

    rc = nci_send_data(ndev, NCI_STATIC_RF_CONN_ID, skb);
    if (rc)
        clear_bit(NCI_DATA_EXCHANGE, &ndev->flags);

    return rc;
}

static struct nfc_ops nci_nfc_ops = {
    .dev_up = nci_dev_up,
    .dev_down = nci_dev_down,
    .start_poll = nci_start_poll,
    .stop_poll = nci_stop_poll,
    .dep_link_up = nci_dep_link_up,
    .dep_link_down = nci_dep_link_down,
    .activate_target = nci_activate_target,
    .deactivate_target = nci_deactivate_target,
    .im_transceive = nci_transceive,
};

/* ---- Interface to NCI drivers ---- */

struct nci_dev *nci_allocate_device(struct nci_ops *ops,
                    __u32 supported_protocols,
                    int tx_headroom, int tx_tailroom)
{
    struct nci_dev *ndev;

    pr_debug("supported_protocols 0x%x\n", supported_protocols);

    if (!ops->open || !ops->close || !ops->send)
        return NULL;

    if (!supported_protocols)
        return NULL;

    ndev = kzalloc(sizeof(struct nci_dev), GFP_KERNEL);
    if (!ndev)
        return NULL;

    ndev->ops = ops;
    ndev->tx_headroom = tx_headroom;
    ndev->tx_tailroom = tx_tailroom;

    ndev->nfc_dev = nfc_allocate_device(&nci_nfc_ops,
                        supported_protocols,
                        tx_headroom + NCI_DATA_HDR_SIZE,
                        tx_tailroom);
    if (!ndev->nfc_dev)
        goto free_exit;

    nfc_set_drvdata(ndev->nfc_dev, ndev);

    return ndev;

free_exit:
    kfree(ndev);
    return NULL;
}
EXPORT_SYMBOL(nci_allocate_device);

void nci_free_device(struct nci_dev *ndev)
{
    nfc_free_device(ndev->nfc_dev);
    kfree(ndev);
}
EXPORT_SYMBOL(nci_free_device);

int nci_register_device(struct nci_dev *ndev)
{
    int rc;
    struct device *dev = &ndev->nfc_dev->dev;
    char name[32];

    rc = nfc_register_device(ndev->nfc_dev);
    if (rc)
        goto exit;

    ndev->flags = 0;

    INIT_WORK(&ndev->cmd_work, nci_cmd_work);
    snprintf(name, sizeof(name), "%s_nci_cmd_wq", dev_name(dev));
    ndev->cmd_wq = create_singlethread_workqueue(name);
    if (!ndev->cmd_wq) {
        rc = -ENOMEM;
        goto unreg_exit;
    }

    INIT_WORK(&ndev->rx_work, nci_rx_work);
    snprintf(name, sizeof(name), "%s_nci_rx_wq", dev_name(dev));
    ndev->rx_wq = create_singlethread_workqueue(name);
    if (!ndev->rx_wq) {
        rc = -ENOMEM;
        goto destroy_cmd_wq_exit;
    }

    INIT_WORK(&ndev->tx_work, nci_tx_work);
    snprintf(name, sizeof(name), "%s_nci_tx_wq", dev_name(dev));
    ndev->tx_wq = create_singlethread_workqueue(name);
    if (!ndev->tx_wq) {
        rc = -ENOMEM;
        goto destroy_rx_wq_exit;
    }

    skb_queue_head_init(&ndev->cmd_q);
    skb_queue_head_init(&ndev->rx_q);
    skb_queue_head_init(&ndev->tx_q);

    setup_timer(&ndev->cmd_timer, nci_cmd_timer,
            (unsigned long) ndev);
    setup_timer(&ndev->data_timer, nci_data_timer,
            (unsigned long) ndev);

    mutex_init(&ndev->req_lock);

    goto exit;

destroy_rx_wq_exit:
    destroy_workqueue(ndev->rx_wq);

destroy_cmd_wq_exit:
    destroy_workqueue(ndev->cmd_wq);

unreg_exit:
    nfc_unregister_device(ndev->nfc_dev);

exit:
    return rc;
}
EXPORT_SYMBOL(nci_register_device);

void nci_unregister_device(struct nci_dev *ndev)
{
    nci_close_device(ndev);

    destroy_workqueue(ndev->cmd_wq);
    destroy_workqueue(ndev->rx_wq);
    destroy_workqueue(ndev->tx_wq);

    nfc_unregister_device(ndev->nfc_dev);
}
EXPORT_SYMBOL(nci_unregister_device);

int nci_recv_frame(struct sk_buff *skb)
{
    struct nci_dev *ndev = (struct nci_dev *) skb->dev;

    pr_debug("len %d\n", skb->len);

    if (!ndev || (!test_bit(NCI_UP, &ndev->flags)
              && !test_bit(NCI_INIT, &ndev->flags))) {
        kfree_skb(skb);
        return -ENXIO;
    }

    /* Queue frame for rx worker thread */
    skb_queue_tail(&ndev->rx_q, skb);
    queue_work(ndev->rx_wq, &ndev->rx_work);

    return 0;
}
EXPORT_SYMBOL(nci_recv_frame);

static int nci_send_frame(struct sk_buff *skb)
{
    struct nci_dev *ndev = (struct nci_dev *) skb->dev;

    pr_debug("len %d\n", skb->len);

    if (!ndev) {
        kfree_skb(skb);
        return -ENODEV;
    }

    /* Get rid of skb owner, prior to sending to the driver. */
    skb_orphan(skb);

    return ndev->ops->send(skb);
}

/* Send NCI command */
int nci_send_cmd(struct nci_dev *ndev, __u16 opcode, __u8 plen, void *payload)
{
    struct nci_ctrl_hdr *hdr;
    struct sk_buff *skb;

    pr_debug("opcode 0x%x, plen %d\n", opcode, plen);

    skb = nci_skb_alloc(ndev, (NCI_CTRL_HDR_SIZE + plen), GFP_KERNEL);
    if (!skb) {
        pr_err("no memory for command\n");
        return -ENOMEM;
    }

    hdr = (struct nci_ctrl_hdr *) skb_put(skb, NCI_CTRL_HDR_SIZE);
    hdr->gid = nci_opcode_gid(opcode);
    hdr->oid = nci_opcode_oid(opcode);
    hdr->plen = plen;

    nci_mt_set((__u8 *)hdr, NCI_MT_CMD_PKT);
    nci_pbf_set((__u8 *)hdr, NCI_PBF_LAST);

    if (plen)
        memcpy(skb_put(skb, plen), payload, plen);

    skb->dev = (void *) ndev;

    skb_queue_tail(&ndev->cmd_q, skb);
    queue_work(ndev->cmd_wq, &ndev->cmd_work);

    return 0;
}

/* ---- NCI TX Data worker thread ---- */

static void nci_tx_work(struct work_struct *work)
{
    struct nci_dev *ndev = container_of(work, struct nci_dev, tx_work);
    struct sk_buff *skb;

    pr_debug("credits_cnt %d\n", atomic_read(&ndev->credits_cnt));

    /* Send queued tx data */
    while (atomic_read(&ndev->credits_cnt)) {
        skb = skb_dequeue(&ndev->tx_q);
        if (!skb)
            return;

        /* Check if data flow control is used */
        if (atomic_read(&ndev->credits_cnt) !=
            NCI_DATA_FLOW_CONTROL_NOT_USED)
            atomic_dec(&ndev->credits_cnt);

        pr_debug("NCI TX: MT=data, PBF=%d, conn_id=%d, plen=%d\n",
             nci_pbf(skb->data),
             nci_conn_id(skb->data),
             nci_plen(skb->data));

        nci_send_frame(skb);

        mod_timer(&ndev->data_timer,
              jiffies + msecs_to_jiffies(NCI_DATA_TIMEOUT));
    }
}

/* ----- NCI RX worker thread (data & control) ----- */

static void nci_rx_work(struct work_struct *work)
{
    struct nci_dev *ndev = container_of(work, struct nci_dev, rx_work);
    struct sk_buff *skb;

    while ((skb = skb_dequeue(&ndev->rx_q))) {
        /* Process frame */
        switch (nci_mt(skb->data)) {
        case NCI_MT_RSP_PKT:
            nci_rsp_packet(ndev, skb);
            break;

        case NCI_MT_NTF_PKT:
            nci_ntf_packet(ndev, skb);
            break;

        case NCI_MT_DATA_PKT:
            nci_rx_data_packet(ndev, skb);
            break;

        default:
            pr_err("unknown MT 0x%x\n", nci_mt(skb->data));
            kfree_skb(skb);
            break;
        }
    }

    /* check if a data exchange timout has occurred */
    if (test_bit(NCI_DATA_EXCHANGE_TO, &ndev->flags)) {
        /* complete the data exchange transaction, if exists */
        if (test_bit(NCI_DATA_EXCHANGE, &ndev->flags))
            nci_data_exchange_complete(ndev, NULL, -ETIMEDOUT);

        clear_bit(NCI_DATA_EXCHANGE_TO, &ndev->flags);
    }
}

/* ----- NCI TX CMD worker thread ----- */

static void nci_cmd_work(struct work_struct *work)
{
    struct nci_dev *ndev = container_of(work, struct nci_dev, cmd_work);
    struct sk_buff *skb;

    pr_debug("cmd_cnt %d\n", atomic_read(&ndev->cmd_cnt));

    /* Send queued command */
    if (atomic_read(&ndev->cmd_cnt)) {
        skb = skb_dequeue(&ndev->cmd_q);
        if (!skb)
            return;

        atomic_dec(&ndev->cmd_cnt);

        pr_debug("NCI TX: MT=cmd, PBF=%d, GID=0x%x, OID=0x%x, plen=%d\n",
             nci_pbf(skb->data),
             nci_opcode_gid(nci_opcode(skb->data)),
             nci_opcode_oid(nci_opcode(skb->data)),
             nci_plen(skb->data));

        nci_send_frame(skb);

        mod_timer(&ndev->cmd_timer,
              jiffies + msecs_to_jiffies(NCI_CMD_TIMEOUT));
    }
}

MODULE_LICENSE("GPL");