// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * LIRC base driver
 *
 * by Artur Lipowski <alipowski@interia.pl>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/device.h>
#include <linux/file.h>
#include <linux/idr.h>
#include <linux/poll.h>
#include <linux/sched.h>
#include <linux/wait.h>

#include "rc-core-priv.h"
#include <uapi/linux/lirc.h>

#define LIRCBUF_SIZE    1024

static dev_t lirc_base_dev;

/* Used to keep track of allocated lirc devices */
static DEFINE_IDA(lirc_ida);

/* Only used for sysfs but defined to void otherwise */
static const struct class lirc_class = {
        .name = "lirc",
};

/**
 * lirc_raw_event() - Send raw IR data to lirc to be relayed to userspace
 *
 * @dev:        the struct rc_dev descriptor of the device
 * @ev:         the struct ir_raw_event descriptor of the pulse/space
 */
void lirc_raw_event(struct rc_dev *dev, struct ir_raw_event ev)
{
        unsigned long flags;
        struct lirc_fh *fh;
        int sample;

        /* Receiver overflow, data missing */
        if (ev.overflow) {
                /*
                 * Send lirc overflow message. This message is unknown to
                 * lircd, but it will interpret this as a long space as
                 * long as the value is set to high value. This resets its
                 * decoder state.
                 */
                sample = LIRC_OVERFLOW(LIRC_VALUE_MASK);
                dev_dbg(&dev->dev, "delivering overflow to lirc_dev\n");

        /* Carrier reports */
        } else if (ev.carrier_report) {
                sample = LIRC_FREQUENCY(ev.carrier);
                dev_dbg(&dev->dev, "carrier report (freq: %d)\n", sample);

        /* Packet end */
        } else if (ev.timeout) {
                dev->gap_start = ktime_get();

                sample = LIRC_TIMEOUT(ev.duration);
                dev_dbg(&dev->dev, "timeout report (duration: %d)\n", sample);

        /* Normal sample */
        } else {
                if (dev->gap_start) {
                        u64 duration = ktime_us_delta(ktime_get(),
                                                      dev->gap_start);

                        /* Cap by LIRC_VALUE_MASK */
                        duration = min_t(u64, duration, LIRC_VALUE_MASK);

                        spin_lock_irqsave(&dev->lirc_fh_lock, flags);
                        list_for_each_entry(fh, &dev->lirc_fh, list)
                                kfifo_put(&fh->rawir, LIRC_SPACE(duration));
                        spin_unlock_irqrestore(&dev->lirc_fh_lock, flags);
                        dev->gap_start = 0;
                }

                sample = ev.pulse ? LIRC_PULSE(ev.duration) :
                                        LIRC_SPACE(ev.duration);
                dev_dbg(&dev->dev, "delivering %uus %s to lirc_dev\n",
                        ev.duration, TO_STR(ev.pulse));
        }

        /*
         * bpf does not care about the gap generated above; that exists
         * for backwards compatibility
         */
        lirc_bpf_run(dev, sample);

        spin_lock_irqsave(&dev->lirc_fh_lock, flags);
        list_for_each_entry(fh, &dev->lirc_fh, list) {
                if (kfifo_put(&fh->rawir, sample))
                        wake_up_poll(&fh->wait_poll, EPOLLIN | EPOLLRDNORM);
        }
        spin_unlock_irqrestore(&dev->lirc_fh_lock, flags);
}

/**
 * lirc_scancode_event() - Send scancode data to lirc to be relayed to
 *              userspace. This can be called in atomic context.
 * @dev:        the struct rc_dev descriptor of the device
 * @lsc:        the struct lirc_scancode describing the decoded scancode
 */
void lirc_scancode_event(struct rc_dev *dev, struct lirc_scancode *lsc)
{
        unsigned long flags;
        struct lirc_fh *fh;

        lsc->timestamp = ktime_get_ns();

        spin_lock_irqsave(&dev->lirc_fh_lock, flags);
        list_for_each_entry(fh, &dev->lirc_fh, list) {
                if (kfifo_put(&fh->scancodes, *lsc))
                        wake_up_poll(&fh->wait_poll, EPOLLIN | EPOLLRDNORM);
        }
        spin_unlock_irqrestore(&dev->lirc_fh_lock, flags);
}
EXPORT_SYMBOL_GPL(lirc_scancode_event);

static int lirc_open(struct inode *inode, struct file *file)
{
        struct rc_dev *dev = container_of(inode->i_cdev, struct rc_dev,
                                          lirc_cdev);
        struct lirc_fh *fh = kzalloc_obj(*fh);
        unsigned long flags;
        int retval;

        if (!fh)
                return -ENOMEM;

        get_device(&dev->dev);

        if (!dev->registered) {
                retval = -ENODEV;
                goto out_fh;
        }

        if (dev->driver_type == RC_DRIVER_IR_RAW) {
                if (kfifo_alloc(&fh->rawir, MAX_IR_EVENT_SIZE, GFP_KERNEL)) {
                        retval = -ENOMEM;
                        goto out_fh;
                }
        }

        if (dev->driver_type != RC_DRIVER_IR_RAW_TX) {
                if (kfifo_alloc(&fh->scancodes, 32, GFP_KERNEL)) {
                        retval = -ENOMEM;
                        goto out_rawir;
                }
        }

        fh->send_mode = LIRC_MODE_PULSE;
        fh->rc = dev;

        if (dev->driver_type == RC_DRIVER_SCANCODE)
                fh->rec_mode = LIRC_MODE_SCANCODE;
        else
                fh->rec_mode = LIRC_MODE_MODE2;

        retval = rc_open(dev);
        if (retval)
                goto out_kfifo;

        init_waitqueue_head(&fh->wait_poll);

        file->private_data = fh;
        spin_lock_irqsave(&dev->lirc_fh_lock, flags);
        list_add(&fh->list, &dev->lirc_fh);
        spin_unlock_irqrestore(&dev->lirc_fh_lock, flags);

        stream_open(inode, file);

        return 0;
out_kfifo:
        if (dev->driver_type != RC_DRIVER_IR_RAW_TX)
                kfifo_free(&fh->scancodes);
out_rawir:
        if (dev->driver_type == RC_DRIVER_IR_RAW)
                kfifo_free(&fh->rawir);
out_fh:
        kfree(fh);
        put_device(&dev->dev);

        return retval;
}

static int lirc_close(struct inode *inode, struct file *file)
{
        struct lirc_fh *fh = file->private_data;
        struct rc_dev *dev = fh->rc;
        unsigned long flags;

        spin_lock_irqsave(&dev->lirc_fh_lock, flags);
        list_del(&fh->list);
        spin_unlock_irqrestore(&dev->lirc_fh_lock, flags);

        if (dev->driver_type == RC_DRIVER_IR_RAW)
                kfifo_free(&fh->rawir);
        if (dev->driver_type != RC_DRIVER_IR_RAW_TX)
                kfifo_free(&fh->scancodes);
        kfree(fh);

        rc_close(dev);
        put_device(&dev->dev);

        return 0;
}

static ssize_t lirc_transmit(struct file *file, const char __user *buf,
                             size_t n, loff_t *ppos)
{
        struct lirc_fh *fh = file->private_data;
        struct rc_dev *dev = fh->rc;
        unsigned int *txbuf;
        struct ir_raw_event *raw = NULL;
        ssize_t ret;
        size_t count;
        ktime_t start;
        s64 towait;
        unsigned int duration = 0; /* signal duration in us */
        int i;

        ret = mutex_lock_interruptible(&dev->lock);
        if (ret)
                return ret;

        if (!dev->registered) {
                ret = -ENODEV;
                goto out_unlock;
        }

        if (!dev->tx_ir) {
                ret = -EINVAL;
                goto out_unlock;
        }

        if (fh->send_mode == LIRC_MODE_SCANCODE) {
                struct lirc_scancode scan;

                if (n != sizeof(scan)) {
                        ret = -EINVAL;
                        goto out_unlock;
                }

                if (copy_from_user(&scan, buf, sizeof(scan))) {
                        ret = -EFAULT;
                        goto out_unlock;
                }

                if (scan.flags || scan.keycode || scan.timestamp ||
                    scan.rc_proto > RC_PROTO_MAX) {
                        ret = -EINVAL;
                        goto out_unlock;
                }

                /* We only have encoders for 32-bit protocols. */
                if (scan.scancode > U32_MAX ||
                    !rc_validate_scancode(scan.rc_proto, scan.scancode)) {
                        ret = -EINVAL;
                        goto out_unlock;
                }

                raw = kmalloc_objs(*raw, LIRCBUF_SIZE);
                if (!raw) {
                        ret = -ENOMEM;
                        goto out_unlock;
                }

                ret = ir_raw_encode_scancode(scan.rc_proto, scan.scancode,
                                             raw, LIRCBUF_SIZE);
                if (ret < 0)
                        goto out_kfree_raw;

                /* drop trailing space */
                if (!(ret % 2))
                        count = ret - 1;
                else
                        count = ret;

                txbuf = kmalloc_array(count, sizeof(unsigned int), GFP_KERNEL);
                if (!txbuf) {
                        ret = -ENOMEM;
                        goto out_kfree_raw;
                }

                for (i = 0; i < count; i++)
                        txbuf[i] = raw[i].duration;

                if (dev->s_tx_carrier) {
                        int carrier = ir_raw_encode_carrier(scan.rc_proto);

                        if (carrier > 0)
                                dev->s_tx_carrier(dev, carrier);
                }
        } else {
                if (n < sizeof(unsigned int) || n % sizeof(unsigned int)) {
                        ret = -EINVAL;
                        goto out_unlock;
                }

                count = n / sizeof(unsigned int);
                if (count > LIRCBUF_SIZE || count % 2 == 0) {
                        ret = -EINVAL;
                        goto out_unlock;
                }

                txbuf = memdup_user(buf, n);
                if (IS_ERR(txbuf)) {
                        ret = PTR_ERR(txbuf);
                        goto out_unlock;
                }
        }

        for (i = 0; i < count; i++) {
                if (txbuf[i] > IR_MAX_DURATION - duration || !txbuf[i]) {
                        ret = -EINVAL;
                        goto out_kfree;
                }

                duration += txbuf[i];
        }

        start = ktime_get();

        ret = dev->tx_ir(dev, txbuf, count);
        if (ret < 0)
                goto out_kfree;

        kfree(txbuf);
        kfree(raw);
        mutex_unlock(&dev->lock);

        /*
         * The lircd gap calculation expects the write function to
         * wait for the actual IR signal to be transmitted before
         * returning.
         */
        towait = ktime_us_delta(ktime_add_us(start, duration),
                                ktime_get());
        if (towait > 0) {
                set_current_state(TASK_INTERRUPTIBLE);
                schedule_timeout(usecs_to_jiffies(towait));
        }

        return n;
out_kfree:
        kfree(txbuf);
out_kfree_raw:
        kfree(raw);
out_unlock:
        mutex_unlock(&dev->lock);
        return ret;
}

static long lirc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
        struct lirc_fh *fh = file->private_data;
        struct rc_dev *dev = fh->rc;
        u32 __user *argp = (u32 __user *)(arg);
        u32 val = 0;
        int ret;

        if (_IOC_DIR(cmd) & _IOC_WRITE) {
                ret = get_user(val, argp);
                if (ret)
                        return ret;
        }

        ret = mutex_lock_interruptible(&dev->lock);
        if (ret)
                return ret;

        if (!dev->registered) {
                ret = -ENODEV;
                goto out;
        }

        switch (cmd) {
        case LIRC_GET_FEATURES:
                if (dev->driver_type == RC_DRIVER_SCANCODE)
                        val |= LIRC_CAN_REC_SCANCODE;

                if (dev->driver_type == RC_DRIVER_IR_RAW) {
                        val |= LIRC_CAN_REC_MODE2;
                        if (dev->rx_resolution)
                                val |= LIRC_CAN_GET_REC_RESOLUTION;
                }

                if (dev->tx_ir) {
                        val |= LIRC_CAN_SEND_PULSE;
                        if (dev->s_tx_mask)
                                val |= LIRC_CAN_SET_TRANSMITTER_MASK;
                        if (dev->s_tx_carrier)
                                val |= LIRC_CAN_SET_SEND_CARRIER;
                        if (dev->s_tx_duty_cycle)
                                val |= LIRC_CAN_SET_SEND_DUTY_CYCLE;
                }

                if (dev->s_rx_carrier_range)
                        val |= LIRC_CAN_SET_REC_CARRIER |
                                LIRC_CAN_SET_REC_CARRIER_RANGE;

                if (dev->s_wideband_receiver)
                        val |= LIRC_CAN_USE_WIDEBAND_RECEIVER;

                if (dev->s_carrier_report)
                        val |= LIRC_CAN_MEASURE_CARRIER;

                if (dev->max_timeout)
                        val |= LIRC_CAN_SET_REC_TIMEOUT;

                break;

        /* mode support */
        case LIRC_GET_REC_MODE:
                if (dev->driver_type == RC_DRIVER_IR_RAW_TX)
                        ret = -ENOTTY;
                else
                        val = fh->rec_mode;
                break;

        case LIRC_SET_REC_MODE:
                switch (dev->driver_type) {
                case RC_DRIVER_IR_RAW_TX:
                        ret = -ENOTTY;
                        break;
                case RC_DRIVER_SCANCODE:
                        if (val != LIRC_MODE_SCANCODE)
                                ret = -EINVAL;
                        break;
                case RC_DRIVER_IR_RAW:
                        if (!(val == LIRC_MODE_MODE2 ||
                              val == LIRC_MODE_SCANCODE))
                                ret = -EINVAL;
                        break;
                }

                if (!ret)
                        fh->rec_mode = val;
                break;

        case LIRC_GET_SEND_MODE:
                if (!dev->tx_ir)
                        ret = -ENOTTY;
                else
                        val = fh->send_mode;
                break;

        case LIRC_SET_SEND_MODE:
                if (!dev->tx_ir)
                        ret = -ENOTTY;
                else if (!(val == LIRC_MODE_PULSE || val == LIRC_MODE_SCANCODE))
                        ret = -EINVAL;
                else
                        fh->send_mode = val;
                break;

        /* TX settings */
        case LIRC_SET_TRANSMITTER_MASK:
                if (!dev->s_tx_mask)
                        ret = -ENOTTY;
                else
                        ret = dev->s_tx_mask(dev, val);
                break;

        case LIRC_SET_SEND_CARRIER:
                if (!dev->s_tx_carrier)
                        ret = -ENOTTY;
                else
                        ret = dev->s_tx_carrier(dev, val);
                break;

        case LIRC_SET_SEND_DUTY_CYCLE:
                if (!dev->s_tx_duty_cycle)
                        ret = -ENOTTY;
                else if (val <= 0 || val >= 100)
                        ret = -EINVAL;
                else
                        ret = dev->s_tx_duty_cycle(dev, val);
                break;

        /* RX settings */
        case LIRC_SET_REC_CARRIER:
                if (!dev->s_rx_carrier_range)
                        ret = -ENOTTY;
                else if (val <= 0)
                        ret = -EINVAL;
                else
                        ret = dev->s_rx_carrier_range(dev, fh->carrier_low,
                                                      val);
                break;

        case LIRC_SET_REC_CARRIER_RANGE:
                if (!dev->s_rx_carrier_range)
                        ret = -ENOTTY;
                else if (val <= 0)
                        ret = -EINVAL;
                else
                        fh->carrier_low = val;
                break;

        case LIRC_GET_REC_RESOLUTION:
                if (!dev->rx_resolution)
                        ret = -ENOTTY;
                else
                        val = dev->rx_resolution;
                break;

        case LIRC_SET_WIDEBAND_RECEIVER:
                if (!dev->s_wideband_receiver)
                        ret = -ENOTTY;
                else
                        ret = dev->s_wideband_receiver(dev, !!val);
                break;

        case LIRC_SET_MEASURE_CARRIER_MODE:
                if (!dev->s_carrier_report)
                        ret = -ENOTTY;
                else
                        ret = dev->s_carrier_report(dev, !!val);
                break;

        /* Generic timeout support */
        case LIRC_GET_MIN_TIMEOUT:
                if (!dev->max_timeout)
                        ret = -ENOTTY;
                else
                        val = dev->min_timeout;
                break;

        case LIRC_GET_MAX_TIMEOUT:
                if (!dev->max_timeout)
                        ret = -ENOTTY;
                else
                        val = dev->max_timeout;
                break;

        case LIRC_SET_REC_TIMEOUT:
                if (!dev->max_timeout) {
                        ret = -ENOTTY;
                } else {
                        if (val < dev->min_timeout || val > dev->max_timeout)
                                ret = -EINVAL;
                        else if (dev->s_timeout)
                                ret = dev->s_timeout(dev, val);
                        else
                                dev->timeout = val;
                }
                break;

        case LIRC_GET_REC_TIMEOUT:
                if (!dev->timeout)
                        ret = -ENOTTY;
                else
                        val = dev->timeout;
                break;

        case LIRC_SET_REC_TIMEOUT_REPORTS:
                if (dev->driver_type != RC_DRIVER_IR_RAW)
                        ret = -ENOTTY;
                break;

        default:
                ret = -ENOTTY;
        }

        if (!ret && _IOC_DIR(cmd) & _IOC_READ)
                ret = put_user(val, argp);

out:
        mutex_unlock(&dev->lock);
        return ret;
}

static __poll_t lirc_poll(struct file *file, struct poll_table_struct *wait)
{
        struct lirc_fh *fh = file->private_data;
        struct rc_dev *rcdev = fh->rc;
        __poll_t events = 0;

        poll_wait(file, &fh->wait_poll, wait);

        if (!rcdev->registered) {
                events = EPOLLHUP | EPOLLERR;
        } else if (rcdev->driver_type != RC_DRIVER_IR_RAW_TX) {
                if (fh->rec_mode == LIRC_MODE_SCANCODE &&
                    !kfifo_is_empty(&fh->scancodes))
                        events = EPOLLIN | EPOLLRDNORM;

                if (fh->rec_mode == LIRC_MODE_MODE2 &&
                    !kfifo_is_empty(&fh->rawir))
                        events = EPOLLIN | EPOLLRDNORM;
        }

        return events;
}

static ssize_t lirc_read_mode2(struct file *file, char __user *buffer,
                               size_t length)
{
        struct lirc_fh *fh = file->private_data;
        struct rc_dev *rcdev = fh->rc;
        unsigned int copied;
        int ret;

        if (length < sizeof(unsigned int) || length % sizeof(unsigned int))
                return -EINVAL;

        do {
                if (kfifo_is_empty(&fh->rawir)) {
                        if (file->f_flags & O_NONBLOCK)
                                return -EAGAIN;

                        ret = wait_event_interruptible(fh->wait_poll,
                                        !kfifo_is_empty(&fh->rawir) ||
                                        !rcdev->registered);
                        if (ret)
                                return ret;
                }

                if (!rcdev->registered)
                        return -ENODEV;

                ret = mutex_lock_interruptible(&rcdev->lock);
                if (ret)
                        return ret;
                ret = kfifo_to_user(&fh->rawir, buffer, length, &copied);
                mutex_unlock(&rcdev->lock);
                if (ret)
                        return ret;
        } while (copied == 0);

        return copied;
}

static ssize_t lirc_read_scancode(struct file *file, char __user *buffer,
                                  size_t length)
{
        struct lirc_fh *fh = file->private_data;
        struct rc_dev *rcdev = fh->rc;
        unsigned int copied;
        int ret;

        if (length < sizeof(struct lirc_scancode) ||
            length % sizeof(struct lirc_scancode))
                return -EINVAL;

        do {
                if (kfifo_is_empty(&fh->scancodes)) {
                        if (file->f_flags & O_NONBLOCK)
                                return -EAGAIN;

                        ret = wait_event_interruptible(fh->wait_poll,
                                        !kfifo_is_empty(&fh->scancodes) ||
                                        !rcdev->registered);
                        if (ret)
                                return ret;
                }

                if (!rcdev->registered)
                        return -ENODEV;

                ret = mutex_lock_interruptible(&rcdev->lock);
                if (ret)
                        return ret;
                ret = kfifo_to_user(&fh->scancodes, buffer, length, &copied);
                mutex_unlock(&rcdev->lock);
                if (ret)
                        return ret;
        } while (copied == 0);

        return copied;
}

static ssize_t lirc_read(struct file *file, char __user *buffer, size_t length,
                         loff_t *ppos)
{
        struct lirc_fh *fh = file->private_data;
        struct rc_dev *rcdev = fh->rc;

        if (rcdev->driver_type == RC_DRIVER_IR_RAW_TX)
                return -EINVAL;

        if (!rcdev->registered)
                return -ENODEV;

        if (fh->rec_mode == LIRC_MODE_MODE2)
                return lirc_read_mode2(file, buffer, length);
        else /* LIRC_MODE_SCANCODE */
                return lirc_read_scancode(file, buffer, length);
}

static const struct file_operations lirc_fops = {
        .owner          = THIS_MODULE,
        .write          = lirc_transmit,
        .unlocked_ioctl = lirc_ioctl,
        .compat_ioctl   = compat_ptr_ioctl,
        .read           = lirc_read,
        .poll           = lirc_poll,
        .open           = lirc_open,
        .release        = lirc_close,
};

static void lirc_release_device(struct device *ld)
{
        struct rc_dev *rcdev = container_of(ld, struct rc_dev, lirc_dev);

        put_device(&rcdev->dev);
}

int lirc_register(struct rc_dev *dev)
{
        const char *rx_type, *tx_type;
        int err, minor;

        minor = ida_alloc_max(&lirc_ida, RC_DEV_MAX - 1, GFP_KERNEL);
        if (minor < 0)
                return minor;

        device_initialize(&dev->lirc_dev);
        dev->lirc_dev.class = &lirc_class;
        dev->lirc_dev.parent = &dev->dev;
        dev->lirc_dev.release = lirc_release_device;
        dev->lirc_dev.devt = MKDEV(MAJOR(lirc_base_dev), minor);
        dev_set_name(&dev->lirc_dev, "lirc%d", minor);

        INIT_LIST_HEAD(&dev->lirc_fh);
        spin_lock_init(&dev->lirc_fh_lock);

        cdev_init(&dev->lirc_cdev, &lirc_fops);

        get_device(&dev->dev);

        err = cdev_device_add(&dev->lirc_cdev, &dev->lirc_dev);
        if (err)
                goto out_put_device;

        switch (dev->driver_type) {
        case RC_DRIVER_SCANCODE:
                rx_type = "scancode";
                break;
        case RC_DRIVER_IR_RAW:
                rx_type = "raw IR";
                break;
        default:
                rx_type = "no";
                break;
        }

        if (dev->tx_ir)
                tx_type = "raw IR";
        else
                tx_type = "no";

        dev_info(&dev->dev, "lirc_dev: driver %s registered at minor = %d, %s receiver, %s transmitter",
                 dev->driver_name, minor, rx_type, tx_type);

        return 0;

out_put_device:
        put_device(&dev->lirc_dev);
        ida_free(&lirc_ida, minor);
        return err;
}

void lirc_unregister(struct rc_dev *dev)
{
        unsigned long flags;
        struct lirc_fh *fh;

        dev_dbg(&dev->dev, "lirc_dev: driver %s unregistered from minor = %d\n",
                dev->driver_name, MINOR(dev->lirc_dev.devt));

        spin_lock_irqsave(&dev->lirc_fh_lock, flags);
        list_for_each_entry(fh, &dev->lirc_fh, list)
                wake_up_poll(&fh->wait_poll, EPOLLHUP | EPOLLERR);
        spin_unlock_irqrestore(&dev->lirc_fh_lock, flags);

        cdev_device_del(&dev->lirc_cdev, &dev->lirc_dev);
        ida_free(&lirc_ida, MINOR(dev->lirc_dev.devt));
}

int __init lirc_dev_init(void)
{
        int retval;

        retval = class_register(&lirc_class);
        if (retval)
                return retval;

        retval = alloc_chrdev_region(&lirc_base_dev, 0, RC_DEV_MAX, "lirc");
        if (retval) {
                class_unregister(&lirc_class);
                pr_err("alloc_chrdev_region failed\n");
                return retval;
        }

        pr_debug("IR Remote Control driver registered, major %d\n",
                 MAJOR(lirc_base_dev));

        return 0;
}

void __exit lirc_dev_exit(void)
{
        class_unregister(&lirc_class);
        unregister_chrdev_region(lirc_base_dev, RC_DEV_MAX);
}

struct rc_dev *rc_dev_get_from_fd(int fd, bool write)
{
        CLASS(fd, f)(fd);
        struct lirc_fh *fh;
        struct rc_dev *dev;

        if (fd_empty(f))
                return ERR_PTR(-EBADF);

        if (fd_file(f)->f_op != &lirc_fops)
                return ERR_PTR(-EINVAL);

        if (write && !(fd_file(f)->f_mode & FMODE_WRITE))
                return ERR_PTR(-EPERM);

        fh = fd_file(f)->private_data;
        dev = fh->rc;

        get_device(&dev->dev);

        return dev;
}

MODULE_ALIAS("lirc_dev");