V4L/DVB: staging/lirc: add lirc_streamzap driver

Signed-off-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Jarod Wilson 2010-07-26 20:32:49 -03:00 committed by Mauro Carvalho Chehab
parent 404f3e956b
commit 19770693c3

View File

@ -0,0 +1,821 @@
/*
* Streamzap Remote Control driver
*
* Copyright (c) 2005 Christoph Bartelmus <lirc@bartelmus.de>
*
* This driver was based on the work of Greg Wickham and Adrian
* Dewhurst. It was substantially rewritten to support correct signal
* gaps and now maintains a delay buffer, which is used to present
* consistent timing behaviour to user space applications. Without the
* delay buffer an ugly hack would be required in lircd, which can
* cause sluggish signal decoding in certain situations.
*
* This driver is based on the USB skeleton driver packaged with the
* kernel; copyright (C) 2001-2003 Greg Kroah-Hartman (greg@kroah.com)
*
* 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/kernel.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/smp_lock.h>
#include <linux/completion.h>
#include <linux/uaccess.h>
#include <linux/usb.h>
#include <media/lirc.h>
#include <media/lirc_dev.h>
#define DRIVER_VERSION "1.28"
#define DRIVER_NAME "lirc_streamzap"
#define DRIVER_DESC "Streamzap Remote Control driver"
static int debug;
#define USB_STREAMZAP_VENDOR_ID 0x0e9c
#define USB_STREAMZAP_PRODUCT_ID 0x0000
/* Use our own dbg macro */
#define dprintk(fmt, args...) \
do { \
if (debug) \
printk(KERN_DEBUG DRIVER_NAME "[%d]: " \
fmt "\n", ## args); \
} while (0)
/* table of devices that work with this driver */
static struct usb_device_id streamzap_table[] = {
/* Streamzap Remote Control */
{ USB_DEVICE(USB_STREAMZAP_VENDOR_ID, USB_STREAMZAP_PRODUCT_ID) },
/* Terminating entry */
{ }
};
MODULE_DEVICE_TABLE(usb, streamzap_table);
#define STREAMZAP_PULSE_MASK 0xf0
#define STREAMZAP_SPACE_MASK 0x0f
#define STREAMZAP_TIMEOUT 0xff
#define STREAMZAP_RESOLUTION 256
/* number of samples buffered */
#define STREAMZAP_BUF_LEN 128
enum StreamzapDecoderState {
PulseSpace,
FullPulse,
FullSpace,
IgnorePulse
};
/* Structure to hold all of our device specific stuff
*
* some remarks regarding locking:
* theoretically this struct can be accessed from three threads:
*
* - from lirc_dev through set_use_inc/set_use_dec
*
* - from the USB layer throuh probe/disconnect/irq
*
* Careful placement of lirc_register_driver/lirc_unregister_driver
* calls will prevent conflicts. lirc_dev makes sure that
* set_use_inc/set_use_dec are not being executed and will not be
* called after lirc_unregister_driver returns.
*
* - by the timer callback
*
* The timer is only running when the device is connected and the
* LIRC device is open. Making sure the timer is deleted by
* set_use_dec will make conflicts impossible.
*/
struct usb_streamzap {
/* usb */
/* save off the usb device pointer */
struct usb_device *udev;
/* the interface for this device */
struct usb_interface *interface;
/* buffer & dma */
unsigned char *buf_in;
dma_addr_t dma_in;
unsigned int buf_in_len;
struct usb_endpoint_descriptor *endpoint;
/* IRQ */
struct urb *urb_in;
/* lirc */
struct lirc_driver *driver;
struct lirc_buffer *delay_buf;
/* timer used to support delay buffering */
struct timer_list delay_timer;
int timer_running;
spinlock_t timer_lock;
/* tracks whether we are currently receiving some signal */
int idle;
/* sum of signal lengths received since signal start */
unsigned long sum;
/* start time of signal; necessary for gap tracking */
struct timeval signal_last;
struct timeval signal_start;
enum StreamzapDecoderState decoder_state;
struct timer_list flush_timer;
int flush;
int in_use;
int timeout_enabled;
};
/* local function prototypes */
static int streamzap_probe(struct usb_interface *interface,
const struct usb_device_id *id);
static void streamzap_disconnect(struct usb_interface *interface);
static void usb_streamzap_irq(struct urb *urb);
static int streamzap_use_inc(void *data);
static void streamzap_use_dec(void *data);
static long streamzap_ioctl(struct file *filep, unsigned int cmd,
unsigned long arg);
static int streamzap_suspend(struct usb_interface *intf, pm_message_t message);
static int streamzap_resume(struct usb_interface *intf);
/* usb specific object needed to register this driver with the usb subsystem */
static struct usb_driver streamzap_driver = {
.name = DRIVER_NAME,
.probe = streamzap_probe,
.disconnect = streamzap_disconnect,
.suspend = streamzap_suspend,
.resume = streamzap_resume,
.id_table = streamzap_table,
};
static void stop_timer(struct usb_streamzap *sz)
{
unsigned long flags;
spin_lock_irqsave(&sz->timer_lock, flags);
if (sz->timer_running) {
sz->timer_running = 0;
spin_unlock_irqrestore(&sz->timer_lock, flags);
del_timer_sync(&sz->delay_timer);
} else {
spin_unlock_irqrestore(&sz->timer_lock, flags);
}
}
static void flush_timeout(unsigned long arg)
{
struct usb_streamzap *sz = (struct usb_streamzap *) arg;
/* finally start accepting data */
sz->flush = 0;
}
static void delay_timeout(unsigned long arg)
{
unsigned long flags;
/* deliver data every 10 ms */
static unsigned long timer_inc =
(10000/(1000000/HZ)) == 0 ? 1 : (10000/(1000000/HZ));
struct usb_streamzap *sz = (struct usb_streamzap *) arg;
int data;
spin_lock_irqsave(&sz->timer_lock, flags);
if (!lirc_buffer_empty(sz->delay_buf) &&
!lirc_buffer_full(sz->driver->rbuf)) {
lirc_buffer_read(sz->delay_buf, (unsigned char *) &data);
lirc_buffer_write(sz->driver->rbuf, (unsigned char *) &data);
}
if (!lirc_buffer_empty(sz->delay_buf)) {
while (lirc_buffer_available(sz->delay_buf) <
STREAMZAP_BUF_LEN / 2 &&
!lirc_buffer_full(sz->driver->rbuf)) {
lirc_buffer_read(sz->delay_buf,
(unsigned char *) &data);
lirc_buffer_write(sz->driver->rbuf,
(unsigned char *) &data);
}
if (sz->timer_running) {
sz->delay_timer.expires = jiffies + timer_inc;
add_timer(&sz->delay_timer);
}
} else {
sz->timer_running = 0;
}
if (!lirc_buffer_empty(sz->driver->rbuf))
wake_up(&sz->driver->rbuf->wait_poll);
spin_unlock_irqrestore(&sz->timer_lock, flags);
}
static void flush_delay_buffer(struct usb_streamzap *sz)
{
int data;
int empty = 1;
while (!lirc_buffer_empty(sz->delay_buf)) {
empty = 0;
lirc_buffer_read(sz->delay_buf, (unsigned char *) &data);
if (!lirc_buffer_full(sz->driver->rbuf)) {
lirc_buffer_write(sz->driver->rbuf,
(unsigned char *) &data);
} else {
dprintk("buffer overflow", sz->driver->minor);
}
}
if (!empty)
wake_up(&sz->driver->rbuf->wait_poll);
}
static void push(struct usb_streamzap *sz, unsigned char *data)
{
unsigned long flags;
spin_lock_irqsave(&sz->timer_lock, flags);
if (lirc_buffer_full(sz->delay_buf)) {
int read_data;
lirc_buffer_read(sz->delay_buf,
(unsigned char *) &read_data);
if (!lirc_buffer_full(sz->driver->rbuf)) {
lirc_buffer_write(sz->driver->rbuf,
(unsigned char *) &read_data);
} else {
dprintk("buffer overflow", sz->driver->minor);
}
}
lirc_buffer_write(sz->delay_buf, data);
if (!sz->timer_running) {
sz->delay_timer.expires = jiffies + HZ/10;
add_timer(&sz->delay_timer);
sz->timer_running = 1;
}
spin_unlock_irqrestore(&sz->timer_lock, flags);
}
static void push_full_pulse(struct usb_streamzap *sz,
unsigned char value)
{
int pulse;
if (sz->idle) {
long deltv;
int tmp;
sz->signal_last = sz->signal_start;
do_gettimeofday(&sz->signal_start);
deltv = sz->signal_start.tv_sec-sz->signal_last.tv_sec;
if (deltv > 15) {
/* really long time */
tmp = LIRC_SPACE(LIRC_VALUE_MASK);
} else {
tmp = (int) (deltv*1000000+
sz->signal_start.tv_usec -
sz->signal_last.tv_usec);
tmp -= sz->sum;
tmp = LIRC_SPACE(tmp);
}
dprintk("ls %u", sz->driver->minor, tmp);
push(sz, (char *)&tmp);
sz->idle = 0;
sz->sum = 0;
}
pulse = ((int) value) * STREAMZAP_RESOLUTION;
pulse += STREAMZAP_RESOLUTION / 2;
sz->sum += pulse;
pulse = LIRC_PULSE(pulse);
dprintk("p %u", sz->driver->minor, pulse & PULSE_MASK);
push(sz, (char *)&pulse);
}
static void push_half_pulse(struct usb_streamzap *sz,
unsigned char value)
{
push_full_pulse(sz, (value & STREAMZAP_PULSE_MASK)>>4);
}
static void push_full_space(struct usb_streamzap *sz,
unsigned char value)
{
int space;
space = ((int) value)*STREAMZAP_RESOLUTION;
space += STREAMZAP_RESOLUTION/2;
sz->sum += space;
space = LIRC_SPACE(space);
dprintk("s %u", sz->driver->minor, space);
push(sz, (char *)&space);
}
static void push_half_space(struct usb_streamzap *sz,
unsigned char value)
{
push_full_space(sz, value & STREAMZAP_SPACE_MASK);
}
/**
* usb_streamzap_irq - IRQ handler
*
* This procedure is invoked on reception of data from
* the usb remote.
*/
static void usb_streamzap_irq(struct urb *urb)
{
struct usb_streamzap *sz;
int len;
unsigned int i = 0;
if (!urb)
return;
sz = urb->context;
len = urb->actual_length;
switch (urb->status) {
case -ECONNRESET:
case -ENOENT:
case -ESHUTDOWN:
/*
* this urb is terminated, clean up.
* sz might already be invalid at this point
*/
dprintk("urb status: %d", -1, urb->status);
return;
default:
break;
}
dprintk("received %d", sz->driver->minor, urb->actual_length);
if (!sz->flush) {
for (i = 0; i < urb->actual_length; i++) {
dprintk("%d: %x", sz->driver->minor,
i, (unsigned char) sz->buf_in[i]);
switch (sz->decoder_state) {
case PulseSpace:
if ((sz->buf_in[i]&STREAMZAP_PULSE_MASK) ==
STREAMZAP_PULSE_MASK) {
sz->decoder_state = FullPulse;
continue;
} else if ((sz->buf_in[i]&STREAMZAP_SPACE_MASK)
== STREAMZAP_SPACE_MASK) {
push_half_pulse(sz, sz->buf_in[i]);
sz->decoder_state = FullSpace;
continue;
} else {
push_half_pulse(sz, sz->buf_in[i]);
push_half_space(sz, sz->buf_in[i]);
}
break;
case FullPulse:
push_full_pulse(sz, sz->buf_in[i]);
sz->decoder_state = IgnorePulse;
break;
case FullSpace:
if (sz->buf_in[i] == STREAMZAP_TIMEOUT) {
sz->idle = 1;
stop_timer(sz);
if (sz->timeout_enabled) {
int timeout =
LIRC_TIMEOUT
(STREAMZAP_TIMEOUT *
STREAMZAP_RESOLUTION);
push(sz, (char *)&timeout);
}
flush_delay_buffer(sz);
} else
push_full_space(sz, sz->buf_in[i]);
sz->decoder_state = PulseSpace;
break;
case IgnorePulse:
if ((sz->buf_in[i]&STREAMZAP_SPACE_MASK) ==
STREAMZAP_SPACE_MASK) {
sz->decoder_state = FullSpace;
continue;
}
push_half_space(sz, sz->buf_in[i]);
sz->decoder_state = PulseSpace;
break;
}
}
}
usb_submit_urb(urb, GFP_ATOMIC);
return;
}
static struct file_operations streamzap_fops = {
.owner = THIS_MODULE,
.unlocked_ioctl = streamzap_ioctl,
.read = lirc_dev_fop_read,
.write = lirc_dev_fop_write,
.poll = lirc_dev_fop_poll,
.open = lirc_dev_fop_open,
.release = lirc_dev_fop_close,
};
/**
* streamzap_probe
*
* Called by usb-core to associated with a candidate device
* On any failure the return value is the ERROR
* On success return 0
*/
static int streamzap_probe(struct usb_interface *interface,
const struct usb_device_id *id)
{
struct usb_device *udev = interface_to_usbdev(interface);
struct usb_host_interface *iface_host;
struct usb_streamzap *sz;
struct lirc_driver *driver;
struct lirc_buffer *lirc_buf;
struct lirc_buffer *delay_buf;
char buf[63], name[128] = "";
int retval = -ENOMEM;
int minor = 0;
/* Allocate space for device driver specific data */
sz = kzalloc(sizeof(struct usb_streamzap), GFP_KERNEL);
if (sz == NULL)
return -ENOMEM;
sz->udev = udev;
sz->interface = interface;
/* Check to ensure endpoint information matches requirements */
iface_host = interface->cur_altsetting;
if (iface_host->desc.bNumEndpoints != 1) {
err("%s: Unexpected desc.bNumEndpoints (%d)", __func__,
iface_host->desc.bNumEndpoints);
retval = -ENODEV;
goto free_sz;
}
sz->endpoint = &(iface_host->endpoint[0].desc);
if ((sz->endpoint->bEndpointAddress & USB_ENDPOINT_DIR_MASK)
!= USB_DIR_IN) {
err("%s: endpoint doesn't match input device 02%02x",
__func__, sz->endpoint->bEndpointAddress);
retval = -ENODEV;
goto free_sz;
}
if ((sz->endpoint->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK)
!= USB_ENDPOINT_XFER_INT) {
err("%s: endpoint attributes don't match xfer 02%02x",
__func__, sz->endpoint->bmAttributes);
retval = -ENODEV;
goto free_sz;
}
if (sz->endpoint->wMaxPacketSize == 0) {
err("%s: endpoint message size==0? ", __func__);
retval = -ENODEV;
goto free_sz;
}
/* Allocate the USB buffer and IRQ URB */
sz->buf_in_len = sz->endpoint->wMaxPacketSize;
sz->buf_in = usb_alloc_coherent(sz->udev, sz->buf_in_len,
GFP_ATOMIC, &sz->dma_in);
if (sz->buf_in == NULL)
goto free_sz;
sz->urb_in = usb_alloc_urb(0, GFP_KERNEL);
if (sz->urb_in == NULL)
goto free_sz;
/* Connect this device to the LIRC sub-system */
driver = kzalloc(sizeof(struct lirc_driver), GFP_KERNEL);
if (!driver)
goto free_sz;
lirc_buf = kmalloc(sizeof(struct lirc_buffer), GFP_KERNEL);
if (!lirc_buf)
goto free_driver;
if (lirc_buffer_init(lirc_buf, sizeof(int), STREAMZAP_BUF_LEN))
goto kfree_lirc_buf;
delay_buf = kmalloc(sizeof(struct lirc_buffer), GFP_KERNEL);
if (!delay_buf)
goto free_lirc_buf;
if (lirc_buffer_init(delay_buf, sizeof(int), STREAMZAP_BUF_LEN))
goto kfree_delay_buf;
sz->driver = driver;
strcpy(sz->driver->name, DRIVER_NAME);
sz->driver->minor = -1;
sz->driver->sample_rate = 0;
sz->driver->code_length = sizeof(int) * 8;
sz->driver->features = LIRC_CAN_REC_MODE2 |
LIRC_CAN_GET_REC_RESOLUTION |
LIRC_CAN_SET_REC_TIMEOUT;
sz->driver->data = sz;
sz->driver->min_timeout = STREAMZAP_TIMEOUT * STREAMZAP_RESOLUTION;
sz->driver->max_timeout = STREAMZAP_TIMEOUT * STREAMZAP_RESOLUTION;
sz->driver->rbuf = lirc_buf;
sz->delay_buf = delay_buf;
sz->driver->set_use_inc = &streamzap_use_inc;
sz->driver->set_use_dec = &streamzap_use_dec;
sz->driver->fops = &streamzap_fops;
sz->driver->dev = &interface->dev;
sz->driver->owner = THIS_MODULE;
sz->idle = 1;
sz->decoder_state = PulseSpace;
init_timer(&sz->delay_timer);
sz->delay_timer.function = delay_timeout;
sz->delay_timer.data = (unsigned long) sz;
sz->timer_running = 0;
spin_lock_init(&sz->timer_lock);
init_timer(&sz->flush_timer);
sz->flush_timer.function = flush_timeout;
sz->flush_timer.data = (unsigned long) sz;
/* Complete final initialisations */
usb_fill_int_urb(sz->urb_in, udev,
usb_rcvintpipe(udev, sz->endpoint->bEndpointAddress),
sz->buf_in, sz->buf_in_len, usb_streamzap_irq, sz,
sz->endpoint->bInterval);
sz->urb_in->transfer_dma = sz->dma_in;
sz->urb_in->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
if (udev->descriptor.iManufacturer
&& usb_string(udev, udev->descriptor.iManufacturer,
buf, sizeof(buf)) > 0)
strlcpy(name, buf, sizeof(name));
if (udev->descriptor.iProduct
&& usb_string(udev, udev->descriptor.iProduct,
buf, sizeof(buf)) > 0)
snprintf(name + strlen(name), sizeof(name) - strlen(name),
" %s", buf);
minor = lirc_register_driver(driver);
if (minor < 0)
goto free_delay_buf;
sz->driver->minor = minor;
usb_set_intfdata(interface, sz);
printk(KERN_INFO DRIVER_NAME "[%d]: %s on usb%d:%d attached\n",
sz->driver->minor, name,
udev->bus->busnum, sz->udev->devnum);
return 0;
free_delay_buf:
lirc_buffer_free(sz->delay_buf);
kfree_delay_buf:
kfree(delay_buf);
free_lirc_buf:
lirc_buffer_free(sz->driver->rbuf);
kfree_lirc_buf:
kfree(lirc_buf);
free_driver:
kfree(driver);
free_sz:
if (retval == -ENOMEM)
err("Out of memory");
if (sz) {
usb_free_urb(sz->urb_in);
usb_free_coherent(udev, sz->buf_in_len, sz->buf_in, sz->dma_in);
kfree(sz);
}
return retval;
}
static int streamzap_use_inc(void *data)
{
struct usb_streamzap *sz = data;
if (!sz) {
dprintk("%s called with no context", -1, __func__);
return -EINVAL;
}
dprintk("set use inc", sz->driver->minor);
lirc_buffer_clear(sz->driver->rbuf);
lirc_buffer_clear(sz->delay_buf);
sz->flush_timer.expires = jiffies + HZ;
sz->flush = 1;
add_timer(&sz->flush_timer);
sz->urb_in->dev = sz->udev;
if (usb_submit_urb(sz->urb_in, GFP_ATOMIC)) {
dprintk("open result = -EIO error submitting urb",
sz->driver->minor);
return -EIO;
}
sz->in_use++;
return 0;
}
static void streamzap_use_dec(void *data)
{
struct usb_streamzap *sz = data;
if (!sz) {
dprintk("%s called with no context", -1, __func__);
return;
}
dprintk("set use dec", sz->driver->minor);
if (sz->flush) {
sz->flush = 0;
del_timer_sync(&sz->flush_timer);
}
usb_kill_urb(sz->urb_in);
stop_timer(sz);
sz->in_use--;
}
static long streamzap_ioctl(struct file *filep, unsigned int cmd,
unsigned long arg)
{
int result = 0;
int val;
struct usb_streamzap *sz = lirc_get_pdata(filep);
switch (cmd) {
case LIRC_GET_REC_RESOLUTION:
result = put_user(STREAMZAP_RESOLUTION, (unsigned int *) arg);
break;
case LIRC_SET_REC_TIMEOUT:
result = get_user(val, (int *)arg);
if (result == 0) {
if (val == STREAMZAP_TIMEOUT * STREAMZAP_RESOLUTION)
sz->timeout_enabled = 1;
else if (val == 0)
sz->timeout_enabled = 0;
else
result = -EINVAL;
}
break;
default:
return lirc_dev_fop_ioctl(filep, cmd, arg);
}
return result;
}
/**
* streamzap_disconnect
*
* Called by the usb core when the device is removed from the system.
*
* This routine guarantees that the driver will not submit any more urbs
* by clearing dev->udev. It is also supposed to terminate any currently
* active urbs. Unfortunately, usb_bulk_msg(), used in streamzap_read(),
* does not provide any way to do this.
*/
static void streamzap_disconnect(struct usb_interface *interface)
{
struct usb_streamzap *sz;
int errnum;
int minor;
sz = usb_get_intfdata(interface);
/* unregister from the LIRC sub-system */
errnum = lirc_unregister_driver(sz->driver->minor);
if (errnum != 0)
dprintk("error in lirc_unregister: (returned %d)",
sz->driver->minor, errnum);
lirc_buffer_free(sz->delay_buf);
lirc_buffer_free(sz->driver->rbuf);
/* unregister from the USB sub-system */
usb_free_urb(sz->urb_in);
usb_free_coherent(sz->udev, sz->buf_in_len, sz->buf_in, sz->dma_in);
minor = sz->driver->minor;
kfree(sz->driver->rbuf);
kfree(sz->driver);
kfree(sz->delay_buf);
kfree(sz);
printk(KERN_INFO DRIVER_NAME "[%d]: disconnected\n", minor);
}
static int streamzap_suspend(struct usb_interface *intf, pm_message_t message)
{
struct usb_streamzap *sz = usb_get_intfdata(intf);
printk(KERN_INFO DRIVER_NAME "[%d]: suspend\n", sz->driver->minor);
if (sz->in_use) {
if (sz->flush) {
sz->flush = 0;
del_timer_sync(&sz->flush_timer);
}
stop_timer(sz);
usb_kill_urb(sz->urb_in);
}
return 0;
}
static int streamzap_resume(struct usb_interface *intf)
{
struct usb_streamzap *sz = usb_get_intfdata(intf);
lirc_buffer_clear(sz->driver->rbuf);
lirc_buffer_clear(sz->delay_buf);
if (sz->in_use) {
sz->flush_timer.expires = jiffies + HZ;
sz->flush = 1;
add_timer(&sz->flush_timer);
sz->urb_in->dev = sz->udev;
if (usb_submit_urb(sz->urb_in, GFP_ATOMIC)) {
dprintk("open result = -EIO error submitting urb",
sz->driver->minor);
return -EIO;
}
}
return 0;
}
/**
* usb_streamzap_init
*/
static int __init usb_streamzap_init(void)
{
int result;
/* register this driver with the USB subsystem */
result = usb_register(&streamzap_driver);
if (result) {
err("usb_register failed. Error number %d",
result);
return result;
}
printk(KERN_INFO DRIVER_NAME " " DRIVER_VERSION " registered\n");
return 0;
}
/**
* usb_streamzap_exit
*/
static void __exit usb_streamzap_exit(void)
{
usb_deregister(&streamzap_driver);
}
module_init(usb_streamzap_init);
module_exit(usb_streamzap_exit);
MODULE_AUTHOR("Christoph Bartelmus, Greg Wickham, Adrian Dewhurst");
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");
module_param(debug, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(debug, "Enable debugging messages");