RK3288 nfc技持的NFC 驱动 pn544 [复制链接]

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/*
* Driver for the PN544 NFC chip.
*
* Copyright (C) Nokia Corporation
*
* Author: Jari Vanhala <ext-jari.vanhala@nokia.com>
* Contact: Matti Aaltonen <matti.j.aaltonen@nokia.com>
*
* 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
*/

#include <linux/completion.h>
#include <linux/crc-ccitt.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/nfc/pn544.h>
#include <linux/poll.h>
#include <linux/regulator/consumer.h>
#include <linux/serial_core.h> /* for TCGETS */
#include <linux/slab.h>

#define DRIVER_CARD    "PN544 NFC"
#define DRIVER_DESC    "NFC driver for PN544"

static struct i2c_device_id pn544_id_table[] = {
    { PN544_DRIVER_NAME, 0 },
    { }
};
MODULE_DEVICE_TABLE(i2c, pn544_id_table);

#define HCI_MODE    0
#define FW_MODE        1

enum pn544_state {
    PN544_ST_COLD,
    PN544_ST_FW_READY,
    PN544_ST_READY,
};

enum pn544_irq {
    PN544_NONE,
    PN544_INT,
};

struct pn544_info {
    struct miscdevice miscdev;
    struct i2c_client *i2c_dev;
    struct regulator_bulk_data regs[3];

    enum pn544_state state;
    wait_queue_head_t read_wait;
    loff_t read_offset;
    enum pn544_irq read_irq;
    struct mutex read_mutex; /* Serialize read_irq access */
    struct mutex mutex; /* Serialize info struct access */
    u8 *buf;
    size_t buflen;
};

static const char reg_vdd_io[]    = "Vdd_IO";
static const char reg_vbat[]    = "VBat";
static const char reg_vsim[]    = "VSim";

/* sysfs interface */
static ssize_t pn544_test(struct device *dev,
              struct device_attribute *attr, char *buf)
{
    struct pn544_info *info = dev_get_drvdata(dev);
    struct i2c_client *client = info->i2c_dev;
    struct pn544_nfc_platform_data *pdata = client->dev.platform_data;

    return snprintf(buf, PAGE_SIZE, "%d\n", pdata->test());
}

static int pn544_enable(struct pn544_info *info, int mode)
{
    struct pn544_nfc_platform_data *pdata;
    struct i2c_client *client = info->i2c_dev;

    int r;

    r = regulator_bulk_enable(ARRAY_SIZE(info->regs), info->regs);
    if (r < 0)
        return r;

    pdata = client->dev.platform_data;
    info->read_irq = PN544_NONE;
    if (pdata->enable)
        pdata->enable(mode);

    if (mode) {
        info->state = PN544_ST_FW_READY;
        dev_dbg(&client->dev, "now in FW-mode\n");
    } else {
        info->state = PN544_ST_READY;
        dev_dbg(&client->dev, "now in HCI-mode\n");
    }

    usleep_range(10000, 15000);

    return 0;
}

static void pn544_disable(struct pn544_info *info)
{
    struct pn544_nfc_platform_data *pdata;
    struct i2c_client *client = info->i2c_dev;

    pdata = client->dev.platform_data;
    if (pdata->disable)
        pdata->disable();

    info->state = PN544_ST_COLD;

    dev_dbg(&client->dev, "Now in OFF-mode\n");

    msleep(PN544_RESETVEN_TIME);

    info->read_irq = PN544_NONE;
    regulator_bulk_disable(ARRAY_SIZE(info->regs), info->regs);
}

static int check_crc(u8 *buf, int buflen)
{
    u8 len;
    u16 crc;

    len = buf[0] + 1;
    if (len < 4 || len != buflen || len > PN544_MSG_MAX_SIZE) {
        pr_err(PN544_DRIVER_NAME
               ": CRC; corrupt packet len %u (%d)\n", len, buflen);
        print_hex_dump(KERN_DEBUG, "crc: ", DUMP_PREFIX_NONE,
                   16, 2, buf, buflen, false);
        return -EPERM;
    }
    crc = crc_ccitt(0xffff, buf, len - 2);
    crc = ~crc;

    if (buf[len-2] != (crc & 0xff) || buf[len-1] != (crc >> 8)) {
        pr_err(PN544_DRIVER_NAME ": CRC error 0x%x != 0x%x 0x%x\n",
               crc, buf[len-1], buf[len-2]);

        print_hex_dump(KERN_DEBUG, "crc: ", DUMP_PREFIX_NONE,
                   16, 2, buf, buflen, false);
        return -EPERM;
    }
    return 0;
}

static int pn544_i2c_write(struct i2c_client *client, u8 *buf, int len)
{
    int r;

    if (len < 4 || len != (buf[0] + 1)) {
        dev_err(&client->dev, "%s: Illegal message length: %d\n",
            __func__, len);
        return -EINVAL;
    }

    if (check_crc(buf, len))
        return -EINVAL;

    usleep_range(3000, 6000);

    r = i2c_master_send(client, buf, len);
    dev_dbg(&client->dev, "send: %d\n", r);

    if (r == -EREMOTEIO) { /* Retry, chip was in standby */
        usleep_range(6000, 10000);
        r = i2c_master_send(client, buf, len);
        dev_dbg(&client->dev, "send2: %d\n", r);
    }

    if (r != len)
        return -EREMOTEIO;

    return r;
}

static int pn544_i2c_read(struct i2c_client *client, u8 *buf, int buflen)
{
    int r;
    u8 len;

    /*
     * You could read a packet in one go, but then you'd need to read
     * max size and rest would be 0xff fill, so we do split reads.
     */
    r = i2c_master_recv(client, &len, 1);
    dev_dbg(&client->dev, "recv1: %d\n", r);

    if (r != 1)
        return -EREMOTEIO;

    if (len < PN544_LLC_HCI_OVERHEAD)
        len = PN544_LLC_HCI_OVERHEAD;
    else if (len > (PN544_MSG_MAX_SIZE - 1))
        len = PN544_MSG_MAX_SIZE - 1;

    if (1 + len > buflen) /* len+(data+crc16) */
        return -EMSGSIZE;

    buf[0] = len;

    r = i2c_master_recv(client, buf + 1, len);
    dev_dbg(&client->dev, "recv2: %d\n", r);

    if (r != len)
        return -EREMOTEIO;

    usleep_range(3000, 6000);

    return r + 1;
}

static int pn544_fw_write(struct i2c_client *client, u8 *buf, int len)
{
    int r;

    dev_dbg(&client->dev, "%s\n", __func__);

    if (len < PN544_FW_HEADER_SIZE ||
        (PN544_FW_HEADER_SIZE + (buf[1] << 8) + buf[2]) != len)
        return -EINVAL;

    r = i2c_master_send(client, buf, len);
    dev_dbg(&client->dev, "fw send: %d\n", r);

    if (r == -EREMOTEIO) { /* Retry, chip was in standby */
        usleep_range(6000, 10000);
        r = i2c_master_send(client, buf, len);
        dev_dbg(&client->dev, "fw send2: %d\n", r);
    }

    if (r != len)
        return -EREMOTEIO;

    return r;
}

static int pn544_fw_read(struct i2c_client *client, u8 *buf, int buflen)
{
    int r, len;

    if (buflen < PN544_FW_HEADER_SIZE)
        return -EINVAL;

    r = i2c_master_recv(client, buf, PN544_FW_HEADER_SIZE);
    dev_dbg(&client->dev, "FW recv1: %d\n", r);

    if (r < 0)
        return r;

    if (r < PN544_FW_HEADER_SIZE)
        return -EINVAL;

    len = (buf[1] << 8) + buf[2];
    if (len == 0) /* just header, no additional data */
        return r;

    if (len > buflen - PN544_FW_HEADER_SIZE)
        return -EMSGSIZE;

    r = i2c_master_recv(client, buf + PN544_FW_HEADER_SIZE, len);
    dev_dbg(&client->dev, "fw recv2: %d\n", r);

    if (r != len)
        return -EINVAL;

    return r + PN544_FW_HEADER_SIZE;
}

static irqreturn_t pn544_irq_thread_fn(int irq, void *dev_id)
{
    struct pn544_info *info = dev_id;
    struct i2c_client *client = info->i2c_dev;

    BUG_ON(!info);
    BUG_ON(irq != info->i2c_dev->irq);

    dev_dbg(&client->dev, "IRQ\n");

    mutex_lock(&info->read_mutex);
    info->read_irq = PN544_INT;
    mutex_unlock(&info->read_mutex);

    wake_up_interruptible(&info->read_wait);

    return IRQ_HANDLED;
}

static enum pn544_irq pn544_irq_state(struct pn544_info *info)
{
    enum pn544_irq irq;

    mutex_lock(&info->read_mutex);
    irq = info->read_irq;
    mutex_unlock(&info->read_mutex);
    /*
     * XXX: should we check GPIO-line status directly?
     * return pdata->irq_status() ? PN544_INT : PN544_NONE;
     */

    return irq;
}

static ssize_t pn544_read(struct file *file, char __user *buf,
              size_t count, loff_t *offset)
{
    struct pn544_info *info = container_of(file->private_data,
                           struct pn544_info, miscdev);
    struct i2c_client *client = info->i2c_dev;
    enum pn544_irq irq;
    size_t len;
    int r = 0;

    dev_dbg(&client->dev, "%s: info: %p, count: %zu\n", __func__,
        info, count);

    mutex_lock(&info->mutex);

    if (info->state == PN544_ST_COLD) {
        r = -ENODEV;
        goto out;
    }

    irq = pn544_irq_state(info);
    if (irq == PN544_NONE) {
        if (file->f_flags & O_NONBLOCK) {
            r = -EAGAIN;
            goto out;
        }

        if (wait_event_interruptible(info->read_wait,
                         (info->read_irq == PN544_INT))) {
            r = -ERESTARTSYS;
            goto out;
        }
    }

    if (info->state == PN544_ST_FW_READY) {
        len = min(count, info->buflen);

        mutex_lock(&info->read_mutex);
        r = pn544_fw_read(info->i2c_dev, info->buf, len);
        info->read_irq = PN544_NONE;
        mutex_unlock(&info->read_mutex);

        if (r < 0) {
            dev_err(&info->i2c_dev->dev, "FW read failed: %d\n", r);
            goto out;
        }

        print_hex_dump(KERN_DEBUG, "FW read: ", DUMP_PREFIX_NONE,
                   16, 2, info->buf, r, false);

        *offset += r;
        if (copy_to_user(buf, info->buf, r)) {
            r = -EFAULT;
            goto out;
        }
    } else {
        len = min(count, info->buflen);

        mutex_lock(&info->read_mutex);
        r = pn544_i2c_read(info->i2c_dev, info->buf, len);
        info->read_irq = PN544_NONE;
        mutex_unlock(&info->read_mutex);

        if (r < 0) {
            dev_err(&info->i2c_dev->dev, "read failed (%d)\n", r);
            goto out;
        }
        print_hex_dump(KERN_DEBUG, "read: ", DUMP_PREFIX_NONE,
                   16, 2, info->buf, r, false);

        *offset += r;
        if (copy_to_user(buf, info->buf, r)) {
            r = -EFAULT;
            goto out;
        }
    }

out:
    mutex_unlock(&info->mutex);

    return r;
}

static unsigned int pn544_poll(struct file *file, poll_table *wait)
{
    struct pn544_info *info = container_of(file->private_data,
                           struct pn544_info, miscdev);
    struct i2c_client *client = info->i2c_dev;
    int r = 0;

    dev_dbg(&client->dev, "%s: info: %p\n", __func__, info);

    mutex_lock(&info->mutex);

    if (info->state == PN544_ST_COLD) {
        r = -ENODEV;
        goto out;
    }

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

    if (pn544_irq_state(info) == PN544_INT) {
        r = POLLIN | POLLRDNORM;
        goto out;
    }
out:
    mutex_unlock(&info->mutex);

    return r;
}

static ssize_t pn544_write(struct file *file, const char __user *buf,
               size_t count, loff_t *ppos)
{
    struct pn544_info *info = container_of(file->private_data,
                           struct pn544_info, miscdev);
    struct i2c_client *client = info->i2c_dev;
    ssize_t    len;
    int r;

    dev_dbg(&client->dev, "%s: info: %p, count %zu\n", __func__,
        info, count);

    mutex_lock(&info->mutex);

    if (info->state == PN544_ST_COLD) {
        r = -ENODEV;
        goto out;
    }

    /*
     * XXX: should we detect rset-writes and clean possible
     * read_irq state
     */
    if (info->state == PN544_ST_FW_READY) {
        size_t fw_len;

        if (count < PN544_FW_HEADER_SIZE) {
            r = -EINVAL;
            goto out;
        }

        len = min(count, info->buflen);
        if (copy_from_user(info->buf, buf, len)) {
            r = -EFAULT;
            goto out;
        }

        print_hex_dump(KERN_DEBUG, "FW write: ", DUMP_PREFIX_NONE,
                   16, 2, info->buf, len, false);

        fw_len = PN544_FW_HEADER_SIZE + (info->buf[1] << 8) +
            info->buf[2];

        if (len > fw_len) /* 1 msg at a time */
            len = fw_len;

        r = pn544_fw_write(info->i2c_dev, info->buf, len);
    } else {
        if (count < PN544_LLC_MIN_SIZE) {
            r = -EINVAL;
            goto out;
        }

        len = min(count, info->buflen);
        if (copy_from_user(info->buf, buf, len)) {
            r = -EFAULT;
            goto out;
        }

        print_hex_dump(KERN_DEBUG, "write: ", DUMP_PREFIX_NONE,
                   16, 2, info->buf, len, false);

        if (len > (info->buf[0] + 1)) /* 1 msg at a time */
            len  = info->buf[0] + 1;

        r = pn544_i2c_write(info->i2c_dev, info->buf, len);
    }
out:
    mutex_unlock(&info->mutex);

    return r;

}

static long pn544_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    struct pn544_info *info = container_of(file->private_data,
                           struct pn544_info, miscdev);
    struct i2c_client *client = info->i2c_dev;
    struct pn544_nfc_platform_data *pdata;
    unsigned int val;
    int r = 0;

    dev_dbg(&client->dev, "%s: info: %p, cmd: 0x%x\n", __func__, info, cmd);

    mutex_lock(&info->mutex);

    if (info->state == PN544_ST_COLD) {
        r = -ENODEV;
        goto out;
    }

    pdata = info->i2c_dev->dev.platform_data;
    switch (cmd) {
    case PN544_GET_FW_MODE:
        dev_dbg(&client->dev, "%s:  PN544_GET_FW_MODE\n", __func__);

        val = (info->state == PN544_ST_FW_READY);
        if (copy_to_user((void __user *)arg, &val, sizeof(val))) {
            r = -EFAULT;
            goto out;
        }

        break;

    case PN544_SET_FW_MODE:
        dev_dbg(&client->dev, "%s:  PN544_SET_FW_MODE\n", __func__);

        if (copy_from_user(&val, (void __user *)arg, sizeof(val))) {
            r = -EFAULT;
            goto out;
        }

        if (val) {
            if (info->state == PN544_ST_FW_READY)
                break;

            pn544_disable(info);
            r = pn544_enable(info, FW_MODE);
            if (r < 0)
                goto out;
        } else {
            if (info->state == PN544_ST_READY)
                break;
            pn544_disable(info);
            r = pn544_enable(info, HCI_MODE);
            if (r < 0)
                goto out;
        }
        file->f_pos = info->read_offset;
        break;

    case TCGETS:
        dev_dbg(&client->dev, "%s:  TCGETS\n", __func__);

        r = -ENOIOCTLCMD;
        break;

    default:
        dev_err(&client->dev, "Unknown ioctl 0x%x\n", cmd);
        r = -ENOIOCTLCMD;
        break;
    }

out:
    mutex_unlock(&info->mutex);

    return r;
}

static int pn544_open(struct inode *inode, struct file *file)
{
    struct pn544_info *info = container_of(file->private_data,
                           struct pn544_info, miscdev);
    struct i2c_client *client = info->i2c_dev;
    int r = 0;

    dev_dbg(&client->dev, "%s: info: %p, client %p\n", __func__,
        info, info->i2c_dev);

    mutex_lock(&info->mutex);

    /*
     * Only 1 at a time.
     * XXX: maybe user (counter) would work better
     */
    if (info->state != PN544_ST_COLD) {
        r = -EBUSY;
        goto out;
    }

    file->f_pos = info->read_offset;
    r = pn544_enable(info, HCI_MODE);

out:
    mutex_unlock(&info->mutex);
    return r;
}

static int pn544_close(struct inode *inode, struct file *file)
{
    struct pn544_info *info = container_of(file->private_data,
                           struct pn544_info, miscdev);
    struct i2c_client *client = info->i2c_dev;

    dev_dbg(&client->dev, "%s: info: %p, client %p\n",
        __func__, info, info->i2c_dev);

    mutex_lock(&info->mutex);
    pn544_disable(info);
    mutex_unlock(&info->mutex);

    return 0;
}

static const struct file_operations pn544_fops = {
    .owner        = THIS_MODULE,
    .llseek        = no_llseek,
    .read        = pn544_read,
    .write        = pn544_write,
    .poll        = pn544_poll,
    .open        = pn544_open,
    .release    = pn544_close,
    .unlocked_ioctl    = pn544_ioctl,
};

#ifdef CONFIG_PM
static int pn544_suspend(struct device *dev)
{
    struct i2c_client *client = to_i2c_client(dev);
    struct pn544_info *info;
    int r = 0;

    dev_info(&client->dev, "***\n%s: client %p\n***\n", __func__, client);

    info = i2c_get_clientdata(client);
    dev_info(&client->dev, "%s: info: %p, client %p\n", __func__,
         info, client);

    mutex_lock(&info->mutex);

    switch (info->state) {
    case PN544_ST_FW_READY:
        /* Do not suspend while upgrading FW, please! */
        r = -EPERM;
        break;

    case PN544_ST_READY:
        /*
         * CHECK: Device should be in standby-mode. No way to check?
         * Allowing low power mode for the regulator is potentially
         * dangerous if pn544 does not go to suspension.
         */
        break;

    case PN544_ST_COLD:
        break;
    };

    mutex_unlock(&info->mutex);
    return r;
}

static int pn544_resume(struct device *dev)
{
    struct i2c_client *client = to_i2c_client(dev);
    struct pn544_info *info = i2c_get_clientdata(client);
    int r = 0;

    dev_dbg(&client->dev, "%s: info: %p, client %p\n", __func__,
        info, client);

    mutex_lock(&info->mutex);

    switch (info->state) {
    case PN544_ST_READY:
        /*
         * CHECK: If regulator low power mode is allowed in
         * pn544_suspend, we should go back to normal mode
         * here.
         */
        break;

    case PN544_ST_COLD:
        break;

    case PN544_ST_FW_READY:
        break;
    };

    mutex_unlock(&info->mutex);

    return r;
}

static SIMPLE_DEV_PM_OPS(pn544_pm_ops, pn544_suspend, pn544_resume);
#endif

static struct device_attribute pn544_attr =
    __ATTR(nfc_test, S_IRUGO, pn544_test, NULL);

static int __devinit pn544_probe(struct i2c_client *client,
                 const struct i2c_device_id *id)
{
    struct pn544_info *info;
    struct pn544_nfc_platform_data *pdata;
    int r = 0;

    dev_dbg(&client->dev, "%s\n", __func__);
    dev_dbg(&client->dev, "IRQ: %d\n", client->irq);

    /* private data allocation */
    info = kzalloc(sizeof(struct pn544_info), GFP_KERNEL);
    if (!info) {
        dev_err(&client->dev,
            "Cannot allocate memory for pn544_info.\n");
        r = -ENOMEM;
        goto err_info_alloc;
    }

    info->buflen = max(PN544_MSG_MAX_SIZE, PN544_MAX_I2C_TRANSFER);
    info->buf = kzalloc(info->buflen, GFP_KERNEL);
    if (!info->buf) {
        dev_err(&client->dev,
            "Cannot allocate memory for pn544_info->buf.\n");
        r = -ENOMEM;
        goto err_buf_alloc;
    }

    info->regs[0].supply = reg_vdd_io;
    info->regs[1].supply = reg_vbat;
    info->regs[2].supply = reg_vsim;
    r = regulator_bulk_get(&client->dev, ARRAY_SIZE(info->regs),
                 info->regs);
    if (r < 0)
        goto err_kmalloc;

    info->i2c_dev = client;
    info->state = PN544_ST_COLD;
    info->read_irq = PN544_NONE;
    mutex_init(&info->read_mutex);
    mutex_init(&info->mutex);
    init_waitqueue_head(&info->read_wait);
    i2c_set_clientdata(client, info);
    pdata = client->dev.platform_data;
    if (!pdata) {
        dev_err(&client->dev, "No platform data\n");
        r = -EINVAL;
        goto err_reg;
    }

    if (!pdata->request_resources) {
        dev_err(&client->dev, "request_resources() missing\n");
        r = -EINVAL;
        goto err_reg;
    }

    r = pdata->request_resources(client);
    if (r) {
        dev_err(&client->dev, "Cannot get platform resources\n");
        goto err_reg;
    }

    r = request_threaded_irq(client->irq, NULL, pn544_irq_thread_fn,
                 IRQF_TRIGGER_RISING, PN544_DRIVER_NAME,
                 info);
    if (r < 0) {
        dev_err(&client->dev, "Unable to register IRQ handler\n");
        goto err_res;
    }

    /* If we don't have the test we don't need the sysfs file */
    if (pdata->test) {
        r = device_create_file(&client->dev, &pn544_attr);
        if (r) {
            dev_err(&client->dev,
                "sysfs registration failed, error %d\n", r);
            goto err_irq;
        }
    }

    info->miscdev.minor = MISC_DYNAMIC_MINOR;
    info->miscdev.name = PN544_DRIVER_NAME;
    info->miscdev.fops = &pn544_fops;
    info->miscdev.parent = &client->dev;
    r = misc_register(&info->miscdev);
    if (r < 0) {
        dev_err(&client->dev, "Device registration failed\n");
        goto err_sysfs;
    }

    dev_dbg(&client->dev, "%s: info: %p, pdata %p, client %p\n",
        __func__, info, pdata, client);

    return 0;

err_sysfs:
    if (pdata->test)
        device_remove_file(&client->dev, &pn544_attr);
err_irq:
    free_irq(client->irq, info);
err_res:
    if (pdata->free_resources)
        pdata->free_resources();
err_reg:
    regulator_bulk_free(ARRAY_SIZE(info->regs), info->regs);
err_kmalloc:
    kfree(info->buf);
err_buf_alloc:
    kfree(info);
err_info_alloc:
    return r;
}

static __devexit int pn544_remove(struct i2c_client *client)
{
    struct pn544_info *info = i2c_get_clientdata(client);
    struct pn544_nfc_platform_data *pdata = client->dev.platform_data;

    dev_dbg(&client->dev, "%s\n", __func__);

    misc_deregister(&info->miscdev);
    if (pdata->test)
        device_remove_file(&client->dev, &pn544_attr);

    if (info->state != PN544_ST_COLD) {
        if (pdata->disable)
            pdata->disable();

        info->read_irq = PN544_NONE;
    }

    free_irq(client->irq, info);
    if (pdata->free_resources)
        pdata->free_resources();

    regulator_bulk_free(ARRAY_SIZE(info->regs), info->regs);
    kfree(info->buf);
    kfree(info);

    return 0;
}

static struct i2c_driver pn544_driver = {
    .driver = {
        .name = PN544_DRIVER_NAME,
#ifdef CONFIG_PM
        .pm = &pn544_pm_ops,
#endif
    },
    .probe = pn544_probe,
    .id_table = pn544_id_table,
    .remove = __devexit_p(pn544_remove),
};

static int __init pn544_init(void)
{
    int r;

    pr_debug(DRIVER_DESC ": %s\n", __func__);

    r = i2c_add_driver(&pn544_driver);
    if (r) {
        pr_err(PN544_DRIVER_NAME ": driver registration failed\n");
        return r;
    }

    return 0;
}

static void __exit pn544_exit(void)
{
    i2c_del_driver(&pn544_driver);
    pr_info(DRIVER_DESC ", Exiting.\n");
}

module_init(pn544_init);
module_exit(pn544_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION(DRIVER_DESC);