path: root/target/linux/brcm2708/patches-3.18/0015-lirc-added-support-for-RaspberryPi-GPIO.patch

From 96fbef3b8f8ab61f7f32d52b54d7993117a5fdbc Mon Sep 17 00:00:00 2001
From: Aron Szabo <aron@aron.ws>
Date: Sat, 16 Jun 2012 12:15:55 +0200
Subject: [PATCH 015/114] lirc: added support for RaspberryPi GPIO

lirc_rpi: Use read_current_timer to determine transmitter delay. Thanks to jjmz and others
See: https://github.com/raspberrypi/linux/issues/525

lirc: Remove restriction on gpio pins that can be used with lirc

Compute Module, for example could use different pins

lirc_rpi: Add parameter to specify input pin pull

Depending on the connected IR circuitry it might be desirable to change the
gpios internal pull from it pull-down default behaviour. Add a module
parameter to allow the user to set it explicitly.

Signed-off-by: Julian Scheel <julian@jusst.de>

lirc-rpi: Use the higher-level irq control functions

This module used to access the irq_chip methods of the
gpio controller directly, rather than going through the
standard enable_irq/irq_set_irq_type functions. This
caused problems on pinctrl-bcm2835 which only implements
the irq_enable/disable methods and not irq_unmask/mask.

lirc-rpi: Correct the interrupt usage

1) Correct the use of enable_irq (i.e. don't call it so often)
2) Correct the shutdown sequence.
3) Avoid a bcm2708_gpio driver quirk by setting the irq flags earlier
---
 drivers/staging/media/lirc/Kconfig    |   6 +
 drivers/staging/media/lirc/Makefile   |   1 +
 drivers/staging/media/lirc/lirc_rpi.c | 659 ++++++++++++++++++++++++++++++++++
 3 files changed, 666 insertions(+)
 create mode 100644 drivers/staging/media/lirc/lirc_rpi.c

--- a/drivers/staging/media/lirc/Kconfig
+++ b/drivers/staging/media/lirc/Kconfig
@@ -38,6 +38,12 @@ config LIRC_PARALLEL
 	help
 	  Driver for Homebrew Parallel Port Receivers
 
+config LIRC_RPI
+	tristate "Homebrew GPIO Port Receiver/Transmitter for the RaspberryPi"
+	depends on LIRC
+	help
+	  Driver for Homebrew GPIO Port Receiver/Transmitter for the RaspberryPi
+
 config LIRC_SASEM
 	tristate "Sasem USB IR Remote"
 	depends on LIRC && USB
--- a/drivers/staging/media/lirc/Makefile
+++ b/drivers/staging/media/lirc/Makefile
@@ -7,6 +7,7 @@ obj-$(CONFIG_LIRC_BT829)	+= lirc_bt829.o
 obj-$(CONFIG_LIRC_IGORPLUGUSB)	+= lirc_igorplugusb.o
 obj-$(CONFIG_LIRC_IMON)		+= lirc_imon.o
 obj-$(CONFIG_LIRC_PARALLEL)	+= lirc_parallel.o
+obj-$(CONFIG_LIRC_RPI)		+= lirc_rpi.o
 obj-$(CONFIG_LIRC_SASEM)	+= lirc_sasem.o
 obj-$(CONFIG_LIRC_SERIAL)	+= lirc_serial.o
 obj-$(CONFIG_LIRC_SIR)		+= lirc_sir.o
--- /dev/null
+++ b/drivers/staging/media/lirc/lirc_rpi.c
@@ -0,0 +1,659 @@
+/*
+ * lirc_rpi.c
+ *
+ * lirc_rpi - Device driver that records pulse- and pause-lengths
+ *	      (space-lengths) (just like the lirc_serial driver does)
+ *	      between GPIO interrupt events on the Raspberry Pi.
+ *	      Lots of code has been taken from the lirc_serial module,
+ *	      so I would like say thanks to the authors.
+ *
+ * Copyright (C) 2012 Aron Robert Szabo <aron@reon.hu>,
+ *		      Michael Bishop <cleverca22@gmail.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/module.h>
+#include <linux/errno.h>
+#include <linux/interrupt.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/time.h>
+#include <linux/timex.h>
+#include <linux/string.h>
+#include <linux/delay.h>
+#include <linux/platform_device.h>
+#include <linux/irq.h>
+#include <linux/spinlock.h>
+#include <media/lirc.h>
+#include <media/lirc_dev.h>
+#include <mach/gpio.h>
+#include <linux/gpio.h>
+
+#include <linux/platform_data/bcm2708.h>
+
+#define LIRC_DRIVER_NAME "lirc_rpi"
+#define RBUF_LEN 256
+#define LIRC_TRANSMITTER_LATENCY 50
+
+#ifndef MAX_UDELAY_MS
+#define MAX_UDELAY_US 5000
+#else
+#define MAX_UDELAY_US (MAX_UDELAY_MS*1000)
+#endif
+
+#define dprintk(fmt, args...)					\
+	do {							\
+		if (debug)					\
+			printk(KERN_DEBUG LIRC_DRIVER_NAME ": "	\
+			       fmt, ## args);			\
+	} while (0)
+
+/* module parameters */
+
+/* set the default GPIO input pin */
+static int gpio_in_pin = 18;
+/* set the default pull behaviour for input pin */
+static int gpio_in_pull = BCM2708_PULL_DOWN;
+/* set the default GPIO output pin */
+static int gpio_out_pin = 17;
+/* enable debugging messages */
+static bool debug;
+/* -1 = auto, 0 = active high, 1 = active low */
+static int sense = -1;
+/* use softcarrier by default */
+static bool softcarrier = 1;
+/* 0 = do not invert output, 1 = invert output */
+static bool invert = 0;
+
+struct gpio_chip *gpiochip;
+static int irq_num;
+
+/* forward declarations */
+static long send_pulse(unsigned long length);
+static void send_space(long length);
+static void lirc_rpi_exit(void);
+
+static struct platform_device *lirc_rpi_dev;
+static struct timeval lasttv = { 0, 0 };
+static struct lirc_buffer rbuf;
+static spinlock_t lock;
+
+/* initialized/set in init_timing_params() */
+static unsigned int freq = 38000;
+static unsigned int duty_cycle = 50;
+static unsigned long period;
+static unsigned long pulse_width;
+static unsigned long space_width;
+
+static void safe_udelay(unsigned long usecs)
+{
+	while (usecs > MAX_UDELAY_US) {
+		udelay(MAX_UDELAY_US);
+		usecs -= MAX_UDELAY_US;
+	}
+	udelay(usecs);
+}
+
+static int init_timing_params(unsigned int new_duty_cycle,
+	unsigned int new_freq)
+{
+	if (1000 * 1000000L / new_freq * new_duty_cycle / 100 <=
+	    LIRC_TRANSMITTER_LATENCY)
+		return -EINVAL;
+	if (1000 * 1000000L / new_freq * (100 - new_duty_cycle) / 100 <=
+	    LIRC_TRANSMITTER_LATENCY)
+		return -EINVAL;
+	duty_cycle = new_duty_cycle;
+	freq = new_freq;
+	period = 1000 * 1000000L / freq;
+	pulse_width = period * duty_cycle / 100;
+	space_width = period - pulse_width;
+	dprintk("in init_timing_params, freq=%d pulse=%ld, "
+		"space=%ld\n", freq, pulse_width, space_width);
+	return 0;
+}
+
+static long send_pulse_softcarrier(unsigned long length)
+{
+	int flag;
+	unsigned long actual, target;
+	unsigned long actual_us, initial_us, target_us;
+
+	length *= 1000;
+
+	actual = 0; target = 0; flag = 0;
+	read_current_timer(&actual_us);
+
+	while (actual < length) {
+		if (flag) {
+			gpiochip->set(gpiochip, gpio_out_pin, invert);
+			target += space_width;
+		} else {
+			gpiochip->set(gpiochip, gpio_out_pin, !invert);
+			target += pulse_width;
+		}
+		initial_us = actual_us;
+		target_us = actual_us + (target - actual) / 1000;
+		/*
+		 * Note - we've checked in ioctl that the pulse/space
+		 * widths are big enough so that d is > 0
+		 */
+		if  ((int)(target_us - actual_us) > 0)
+			udelay(target_us - actual_us);
+		read_current_timer(&actual_us);
+		actual += (actual_us - initial_us) * 1000;
+		flag = !flag;
+	}
+	return (actual-length) / 1000;
+}
+
+static long send_pulse(unsigned long length)
+{
+	if (length <= 0)
+		return 0;
+
+	if (softcarrier) {
+		return send_pulse_softcarrier(length);
+	} else {
+		gpiochip->set(gpiochip, gpio_out_pin, !invert);
+		safe_udelay(length);
+		return 0;
+	}
+}
+
+static void send_space(long length)
+{
+	gpiochip->set(gpiochip, gpio_out_pin, invert);
+	if (length <= 0)
+		return;
+	safe_udelay(length);
+}
+
+static void rbwrite(int l)
+{
+	if (lirc_buffer_full(&rbuf)) {
+		/* no new signals will be accepted */
+		dprintk("Buffer overrun\n");
+		return;
+	}
+	lirc_buffer_write(&rbuf, (void *)&l);
+}
+
+static void frbwrite(int l)
+{
+	/* simple noise filter */
+	static int pulse, space;
+	static unsigned int ptr;
+
+	if (ptr > 0 && (l & PULSE_BIT)) {
+		pulse += l & PULSE_MASK;
+		if (pulse > 250) {
+			rbwrite(space);
+			rbwrite(pulse | PULSE_BIT);
+			ptr = 0;
+			pulse = 0;
+		}
+		return;
+	}
+	if (!(l & PULSE_BIT)) {
+		if (ptr == 0) {
+			if (l > 20000) {
+				space = l;
+				ptr++;
+				return;
+			}
+		} else {
+			if (l > 20000) {
+				space += pulse;
+				if (space > PULSE_MASK)
+					space = PULSE_MASK;
+				space += l;
+				if (space > PULSE_MASK)
+					space = PULSE_MASK;
+				pulse = 0;
+				return;
+			}
+			rbwrite(space);
+			rbwrite(pulse | PULSE_BIT);
+			ptr = 0;
+			pulse = 0;
+		}
+	}
+	rbwrite(l);
+}
+
+static irqreturn_t irq_handler(int i, void *blah, struct pt_regs *regs)
+{
+	struct timeval tv;
+	long deltv;
+	int data;
+	int signal;
+
+	/* use the GPIO signal level */
+	signal = gpiochip->get(gpiochip, gpio_in_pin);
+
+	if (sense != -1) {
+		/* get current time */
+		do_gettimeofday(&tv);
+
+		/* calc time since last interrupt in microseconds */
+		deltv = tv.tv_sec-lasttv.tv_sec;
+		if (tv.tv_sec < lasttv.tv_sec ||
+		    (tv.tv_sec == lasttv.tv_sec &&
+		     tv.tv_usec < lasttv.tv_usec)) {
+			printk(KERN_WARNING LIRC_DRIVER_NAME
+			       ": AIEEEE: your clock just jumped backwards\n");
+			printk(KERN_WARNING LIRC_DRIVER_NAME
+			       ": %d %d %lx %lx %lx %lx\n", signal, sense,
+			       tv.tv_sec, lasttv.tv_sec,
+			       tv.tv_usec, lasttv.tv_usec);
+			data = PULSE_MASK;
+		} else if (deltv > 15) {
+			data = PULSE_MASK; /* really long time */
+			if (!(signal^sense)) {
+				/* sanity check */
+				printk(KERN_WARNING LIRC_DRIVER_NAME
+				       ": AIEEEE: %d %d %lx %lx %lx %lx\n",
+				       signal, sense, tv.tv_sec, lasttv.tv_sec,
+				       tv.tv_usec, lasttv.tv_usec);
+				/*
+				 * detecting pulse while this
+				 * MUST be a space!
+				 */
+				sense = sense ? 0 : 1;
+			}
+		} else {
+			data = (int) (deltv*1000000 +
+				      (tv.tv_usec - lasttv.tv_usec));
+		}
+		frbwrite(signal^sense ? data : (data|PULSE_BIT));
+		lasttv = tv;
+		wake_up_interruptible(&rbuf.wait_poll);
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int is_right_chip(struct gpio_chip *chip, void *data)
+{
+	dprintk("is_right_chip %s %d\n", chip->label, strcmp(data, chip->label));
+
+	if (strcmp(data, chip->label) == 0)
+		return 1;
+	return 0;
+}
+
+static int init_port(void)
+{
+	int i, nlow, nhigh, ret;
+
+	gpiochip = gpiochip_find("bcm2708_gpio", is_right_chip);
+
+	if (!gpiochip)
+		return -ENODEV;
+
+	if (gpio_request(gpio_out_pin, LIRC_DRIVER_NAME " ir/out")) {
+		printk(KERN_ALERT LIRC_DRIVER_NAME
+		       ": cant claim gpio pin %d\n", gpio_out_pin);
+		ret = -ENODEV;
+		goto exit_init_port;
+	}
+
+	if (gpio_request(gpio_in_pin, LIRC_DRIVER_NAME " ir/in")) {
+		printk(KERN_ALERT LIRC_DRIVER_NAME
+		       ": cant claim gpio pin %d\n", gpio_in_pin);
+		ret = -ENODEV;
+		goto exit_gpio_free_out_pin;
+	}
+
+	bcm2708_gpio_setpull(gpiochip, gpio_in_pin, gpio_in_pull);
+	gpiochip->direction_input(gpiochip, gpio_in_pin);
+	gpiochip->direction_output(gpiochip, gpio_out_pin, 1);
+	gpiochip->set(gpiochip, gpio_out_pin, invert);
+
+	irq_num = gpiochip->to_irq(gpiochip, gpio_in_pin);
+	dprintk("to_irq %d\n", irq_num);
+
+	/* if pin is high, then this must be an active low receiver. */
+	if (sense == -1) {
+		/* wait 1/2 sec for the power supply */
+		msleep(500);
+
+		/*
+		 * probe 9 times every 0.04s, collect "votes" for
+		 * active high/low
+		 */
+		nlow = 0;
+		nhigh = 0;
+		for (i = 0; i < 9; i++) {
+			if (gpiochip->get(gpiochip, gpio_in_pin))
+				nlow++;
+			else
+				nhigh++;
+			msleep(40);
+		}
+		sense = (nlow >= nhigh ? 1 : 0);
+		printk(KERN_INFO LIRC_DRIVER_NAME
+		       ": auto-detected active %s receiver on GPIO pin %d\n",
+		       sense ? "low" : "high", gpio_in_pin);
+	} else {
+		printk(KERN_INFO LIRC_DRIVER_NAME
+		       ": manually using active %s receiver on GPIO pin %d\n",
+		       sense ? "low" : "high", gpio_in_pin);
+	}
+
+	return 0;
+
+	exit_gpio_free_out_pin:
+	gpio_free(gpio_out_pin);
+
+	exit_init_port:
+	return ret;
+}
+
+// called when the character device is opened
+static int set_use_inc(void *data)
+{
+	int result;
+
+	/* initialize timestamp */
+	do_gettimeofday(&lasttv);
+
+	result = request_irq(irq_num,
+			     (irq_handler_t) irq_handler,
+			     IRQ_TYPE_EDGE_RISING | IRQ_TYPE_EDGE_FALLING,
+			     LIRC_DRIVER_NAME, (void*) 0);
+
+	switch (result) {
+	case -EBUSY:
+		printk(KERN_ERR LIRC_DRIVER_NAME
+		       ": IRQ %d is busy\n",
+		       irq_num);
+		return -EBUSY;
+	case -EINVAL:
+		printk(KERN_ERR LIRC_DRIVER_NAME
+		       ": Bad irq number or handler\n");
+		return -EINVAL;
+	default:
+		dprintk("Interrupt %d obtained\n",
+			irq_num);
+		break;
+	};
+
+	/* initialize pulse/space widths */
+	init_timing_params(duty_cycle, freq);
+
+	return 0;
+}
+
+static void set_use_dec(void *data)
+{
+	/* GPIO Pin Falling/Rising Edge Detect Disable */
+	irq_set_irq_type(irq_num, 0);
+	disable_irq(irq_num);
+
+	free_irq(irq_num, (void *) 0);
+
+	dprintk(KERN_INFO LIRC_DRIVER_NAME
+		": freed IRQ %d\n", irq_num);
+}
+
+static ssize_t lirc_write(struct file *file, const char *buf,
+	size_t n, loff_t *ppos)
+{
+	int i, count;
+	unsigned long flags;
+	long delta = 0;
+	int *wbuf;
+
+	count = n / sizeof(int);
+	if (n % sizeof(int) || count % 2 == 0)
+		return -EINVAL;
+	wbuf = memdup_user(buf, n);
+	if (IS_ERR(wbuf))
+		return PTR_ERR(wbuf);
+	spin_lock_irqsave(&lock, flags);
+
+	for (i = 0; i < count; i++) {
+		if (i%2)
+			send_space(wbuf[i] - delta);
+		else
+			delta = send_pulse(wbuf[i]);
+	}
+	gpiochip->set(gpiochip, gpio_out_pin, invert);
+
+	spin_unlock_irqrestore(&lock, flags);
+	kfree(wbuf);
+	return n;
+}
+
+static long lirc_ioctl(struct file *filep, unsigned int cmd, unsigned long arg)
+{
+	int result;
+	__u32 value;
+
+	switch (cmd) {
+	case LIRC_GET_SEND_MODE:
+		return -ENOIOCTLCMD;
+		break;
+
+	case LIRC_SET_SEND_MODE:
+		result = get_user(value, (__u32 *) arg);
+		if (result)
+			return result;
+		/* only LIRC_MODE_PULSE supported */
+		if (value != LIRC_MODE_PULSE)
+			return -ENOSYS;
+		break;
+
+	case LIRC_GET_LENGTH:
+		return -ENOSYS;
+		break;
+
+	case LIRC_SET_SEND_DUTY_CYCLE:
+		dprintk("SET_SEND_DUTY_CYCLE\n");
+		result = get_user(value, (__u32 *) arg);
+		if (result)
+			return result;
+		if (value <= 0 || value > 100)
+			return -EINVAL;
+		return init_timing_params(value, freq);
+		break;
+
+	case LIRC_SET_SEND_CARRIER:
+		dprintk("SET_SEND_CARRIER\n");
+		result = get_user(value, (__u32 *) arg);
+		if (result)
+			return result;
+		if (value > 500000 || value < 20000)
+			return -EINVAL;
+		return init_timing_params(duty_cycle, value);
+		break;
+
+	default:
+		return lirc_dev_fop_ioctl(filep, cmd, arg);
+	}
+	return 0;
+}
+
+static const struct file_operations lirc_fops = {
+	.owner		= THIS_MODULE,
+	.write		= lirc_write,
+	.unlocked_ioctl	= lirc_ioctl,
+	.read		= lirc_dev_fop_read,
+	.poll		= lirc_dev_fop_poll,
+	.open		= lirc_dev_fop_open,
+	.release	= lirc_dev_fop_close,
+	.llseek		= no_llseek,
+};
+
+static struct lirc_driver driver = {
+	.name		= LIRC_DRIVER_NAME,
+	.minor		= -1,
+	.code_length	= 1,
+	.sample_rate	= 0,
+	.data		= NULL,
+	.add_to_buf	= NULL,
+	.rbuf		= &rbuf,
+	.set_use_inc	= set_use_inc,
+	.set_use_dec	= set_use_dec,
+	.fops		= &lirc_fops,
+	.dev		= NULL,
+	.owner		= THIS_MODULE,
+};
+
+static struct platform_driver lirc_rpi_driver = {
+	.driver = {
+		.name   = LIRC_DRIVER_NAME,
+		.owner  = THIS_MODULE,
+	},
+};
+
+static int __init lirc_rpi_init(void)
+{
+	int result;
+
+	/* Init read buffer. */
+	result = lirc_buffer_init(&rbuf, sizeof(int), RBUF_LEN);
+	if (result < 0)
+		return -ENOMEM;
+
+	result = platform_driver_register(&lirc_rpi_driver);
+	if (result) {
+		printk(KERN_ERR LIRC_DRIVER_NAME
+		       ": lirc register returned %d\n", result);
+		goto exit_buffer_free;
+	}
+
+	lirc_rpi_dev = platform_device_alloc(LIRC_DRIVER_NAME, 0);
+	if (!lirc_rpi_dev) {
+		result = -ENOMEM;
+		goto exit_driver_unregister;
+	}
+
+	result = platform_device_add(lirc_rpi_dev);
+	if (result)
+		goto exit_device_put;
+
+	return 0;
+
+	exit_device_put:
+	platform_device_put(lirc_rpi_dev);
+
+	exit_driver_unregister:
+	platform_driver_unregister(&lirc_rpi_driver);
+
+	exit_buffer_free:
+	lirc_buffer_free(&rbuf);
+
+	return result;
+}
+
+static void lirc_rpi_exit(void)
+{
+	if (!lirc_rpi_dev->dev.of_node)
+		platform_device_unregister(lirc_rpi_dev);
+	platform_driver_unregister(&lirc_rpi_driver);
+	lirc_buffer_free(&rbuf);
+}
+
+static int __init lirc_rpi_init_module(void)
+{
+	int result;
+
+	result = lirc_rpi_init();
+	if (result)
+		return result;
+
+	if (gpio_in_pin >= BCM2708_NR_GPIOS || gpio_out_pin >= BCM2708_NR_GPIOS) {
+		result = -EINVAL;
+		printk(KERN_ERR LIRC_DRIVER_NAME
+		       ": invalid GPIO pin(s) specified!\n");
+		goto exit_rpi;
+	}
+
+	result = init_port();
+	if (result < 0)
+		goto exit_rpi;
+
+	driver.features = LIRC_CAN_SET_SEND_DUTY_CYCLE |
+			  LIRC_CAN_SET_SEND_CARRIER |
+			  LIRC_CAN_SEND_PULSE |
+			  LIRC_CAN_REC_MODE2;
+
+	driver.dev = &lirc_rpi_dev->dev;
+	driver.minor = lirc_register_driver(&driver);
+
+	if (driver.minor < 0) {
+		printk(KERN_ERR LIRC_DRIVER_NAME
+		       ": device registration failed with %d\n", result);
+		result = -EIO;
+		goto exit_rpi;
+	}
+
+	printk(KERN_INFO LIRC_DRIVER_NAME ": driver registered!\n");
+
+	return 0;
+
+	exit_rpi:
+	lirc_rpi_exit();
+
+	return result;
+}
+
+static void __exit lirc_rpi_exit_module(void)
+{
+	lirc_unregister_driver(driver.minor);
+
+	gpio_free(gpio_out_pin);
+	gpio_free(gpio_in_pin);
+
+	lirc_rpi_exit();
+
+	printk(KERN_INFO LIRC_DRIVER_NAME ": cleaned up module\n");
+}
+
+module_init(lirc_rpi_init_module);
+module_exit(lirc_rpi_exit_module);
+
+MODULE_DESCRIPTION("Infra-red receiver and blaster driver for Raspberry Pi GPIO.");
+MODULE_AUTHOR("Aron Robert Szabo <aron@reon.hu>");
+MODULE_AUTHOR("Michael Bishop <cleverca22@gmail.com>");
+MODULE_LICENSE("GPL");
+
+module_param(gpio_out_pin, int, S_IRUGO);
+MODULE_PARM_DESC(gpio_out_pin, "GPIO output/transmitter pin number of the BCM"
+		 " processor. (default 17");
+
+module_param(gpio_in_pin, int, S_IRUGO);
+MODULE_PARM_DESC(gpio_in_pin, "GPIO input pin number of the BCM processor."
+		 " (default 18");
+
+module_param(gpio_in_pull, int, S_IRUGO);
+MODULE_PARM_DESC(gpio_in_pull, "GPIO input pin pull configuration."
+		 " (0 = off, 1 = up, 2 = down, default down)");
+
+module_param(sense, int, S_IRUGO);
+MODULE_PARM_DESC(sense, "Override autodetection of IR receiver circuit"
+		 " (0 = active high, 1 = active low )");
+
+module_param(softcarrier, bool, S_IRUGO);
+MODULE_PARM_DESC(softcarrier, "Software carrier (0 = off, 1 = on, default on)");
+
+module_param(invert, bool, S_IRUGO);
+MODULE_PARM_DESC(invert, "Invert output (0 = off, 1 = on, default off");
+
+module_param(debug, bool, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(debug, "Enable debugging messages");