/*
 * 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.
 */

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

#include "nfc.h"

#define VERSION "0.1"

int nfc_devlist_generation;
DEFINE_MUTEX(nfc_devlist_mutex);

int nfc_printk(const char *level, const char *format, ...)
{
        struct va_format vaf;
        va_list args;
        int r;

        va_start(args, format);

        vaf.fmt = format;
        vaf.va = &args;

        r = printk("%sNFC: %pV\n", level, &vaf);

        va_end(args);

        return r;
}
EXPORT_SYMBOL(nfc_printk);

/**
 * 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;

        nfc_dbg("dev_name=%s", 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->ops->dev_up)
                rc = dev->ops->dev_up(dev);

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

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;

        nfc_dbg("dev_name=%s", 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->remote_activated) {
                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;
}

/**
 * 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 protocols)
{
        int rc;

        nfc_dbg("dev_name=%s protocols=0x%x", dev_name(&dev->dev), protocols);

        if (!protocols)
                return -EINVAL;

        device_lock(&dev->dev);

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

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

        rc = dev->ops->start_poll(dev, protocols);
        if (!rc)
                dev->polling = true;

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;

        nfc_dbg("dev_name=%s", 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;

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

/**
 * 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;

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

        device_lock(&dev->dev);

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

        rc = dev->ops->activate_target(dev, target_idx, protocol);
        if (!rc)
                dev->remote_activated = true;

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;

        nfc_dbg("dev_name=%s target_idx=%u", dev_name(&dev->dev), target_idx);

        device_lock(&dev->dev);

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

        dev->ops->deactivate_target(dev, target_idx);
        dev->remote_activated = false;

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;

        nfc_dbg("dev_name=%s target_idx=%u skb->len=%u", 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;
        }

        rc = dev->ops->data_exchange(dev, target_idx, skb, cb, cb_context);

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

/**
 * nfc_alloc_skb - allocate a skb for data exchange responses
 *
 * @size: size to allocate
 * @gfp: gfp flags
 */
struct sk_buff *nfc_alloc_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_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.
 */
int nfc_targets_found(struct nfc_dev *dev, struct nfc_target *targets,
                                                        int n_targets)
{
        int i;

        nfc_dbg("dev_name=%s n_targets=%d", dev_name(&dev->dev), n_targets);

        dev->polling = false;

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

        spin_lock_bh(&dev->targets_lock);

        dev->targets_generation++;

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

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

        dev->n_targets = n_targets;
        spin_unlock_bh(&dev->targets_lock);

        nfc_genl_targets_found(dev);

        return 0;
}
EXPORT_SYMBOL(nfc_targets_found);

static void nfc_release(struct device *d)
{
        struct nfc_dev *dev = to_nfc_dev(d);

        nfc_dbg("dev_name=%s", dev_name(&dev->dev));

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

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

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

        return dev->idx == *idx;
}

struct nfc_dev *nfc_get_device(unsigned 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)
{
        static atomic_t dev_no = ATOMIC_INIT(0);
        struct nfc_dev *dev;

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

        if (!supported_protocols)
                return NULL;

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

        dev->dev.class = &nfc_class;
        dev->idx = atomic_inc_return(&dev_no) - 1;
        dev_set_name(&dev->dev, "nfc%d", dev->idx);
        device_initialize(&dev->dev);

        dev->ops = ops;
        dev->supported_protocols = supported_protocols;
        dev->tx_headroom = tx_headroom;
        dev->tx_tailroom = tx_tailroom;

        spin_lock_init(&dev->targets_lock);
        nfc_genl_data_init(&dev->genl_data);

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

        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;

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


        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;

        nfc_dbg("dev_name=%s", dev_name(&dev->dev));

        mutex_lock(&nfc_devlist_mutex);
        nfc_devlist_generation++;

        /* lock to avoid unregistering a device while an operation
           is in progress */
        device_lock(&dev->dev);
        device_del(&dev->dev);
        device_unlock(&dev->dev);

        mutex_unlock(&nfc_devlist_mutex);

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

}
EXPORT_SYMBOL(nfc_unregister_device);

static int __init nfc_init(void)
{
        int rc;

        nfc_info("NFC Core ver %s", 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 = af_nfc_init();
        if (rc)
                goto err_af_nfc;

        return 0;

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

static void __exit nfc_exit(void)
{
        af_nfc_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");