Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/vapier...

[deliverable/linux.git] / drivers / staging / lirc / lirc_serial.c

/*
 * lirc_serial.c
 *
 * lirc_serial - Device driver that records pulse- and pause-lengths
 *             (space-lengths) between DDCD event on a serial port.
 *
 * Copyright (C) 1996,97 Ralph Metzler <rjkm@thp.uni-koeln.de>
 * Copyright (C) 1998 Trent Piepho <xyzzy@u.washington.edu>
 * Copyright (C) 1998 Ben Pfaff <blp@gnu.org>
 * Copyright (C) 1999 Christoph Bartelmus <lirc@bartelmus.de>
 * Copyright (C) 2007 Andrei Tanas <andrei@tanas.ca> (suspend/resume support)
 *  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
 *
 */

/*
 * Steve's changes to improve transmission fidelity:
 *   - for systems with the rdtsc instruction and the clock counter, a
 *     send_pule that times the pulses directly using the counter.
 *     This means that the LIRC_SERIAL_TRANSMITTER_LATENCY fudge is
 *     not needed. Measurement shows very stable waveform, even where
 *     PCI activity slows the access to the UART, which trips up other
 *     versions.
 *   - For other system, non-integer-microsecond pulse/space lengths,
 *     done using fixed point binary. So, much more accurate carrier
 *     frequency.
 *   - fine tuned transmitter latency, taking advantage of fractional
 *     microseconds in previous change
 *   - Fixed bug in the way transmitter latency was accounted for by
 *     tuning the pulse lengths down - the send_pulse routine ignored
 *     this overhead as it timed the overall pulse length - so the
 *     pulse frequency was right but overall pulse length was too
 *     long. Fixed by accounting for latency on each pulse/space
 *     iteration.
 *
 * Steve Davies <steve@daviesfam.org>  July 2001
 */

#include <linux/module.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/kernel.h>
#include <linux/serial_reg.h>
#include <linux/time.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/wait.h>
#include <linux/mm.h>
#include <linux/delay.h>
#include <linux/poll.h>
#include <linux/platform_device.h>

#include <asm/system.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/fcntl.h>
#include <linux/spinlock.h>

#ifdef CONFIG_LIRC_SERIAL_NSLU2
#include <asm/hardware.h>
#endif
/* From Intel IXP42X Developer's Manual (#252480-005): */
/* ftp://download.intel.com/design/network/manuals/25248005.pdf */
#define UART_IE_IXP42X_UUE   0x40 /* IXP42X UART Unit enable */
#define UART_IE_IXP42X_RTOIE 0x10 /* IXP42X Receiver Data Timeout int.enable */

#include <media/lirc.h>
#include <media/lirc_dev.h>

#define LIRC_DRIVER_NAME "lirc_serial"

struct lirc_serial {
        int signal_pin;
        int signal_pin_change;
        u8 on;
        u8 off;
        long (*send_pulse)(unsigned long length);
        void (*send_space)(long length);
        int features;
        spinlock_t lock;
};

#define LIRC_HOMEBREW           0
#define LIRC_IRDEO              1
#define LIRC_IRDEO_REMOTE       2
#define LIRC_ANIMAX             3
#define LIRC_IGOR               4
#define LIRC_NSLU2              5

/*** module parameters ***/
static int type;
static int io;
static int irq;
static int iommap;
static int ioshift;
static int softcarrier = 1;
static int share_irq;
static int debug;
static int sense = -1;  /* -1 = auto, 0 = active high, 1 = active low */
static int txsense;     /* 0 = active high, 1 = active low */

#define dprintk(fmt, args...)                                   \
        do {                                                    \
                if (debug)                                      \
                        printk(KERN_DEBUG LIRC_DRIVER_NAME ": " \
                               fmt, ## args);                   \
        } while (0)

/* forward declarations */
static long send_pulse_irdeo(unsigned long length);
static long send_pulse_homebrew(unsigned long length);
static void send_space_irdeo(long length);
static void send_space_homebrew(long length);

static struct lirc_serial hardware[] = {
        [LIRC_HOMEBREW] = {
                .signal_pin        = UART_MSR_DCD,
                .signal_pin_change = UART_MSR_DDCD,
                .on  = (UART_MCR_RTS | UART_MCR_OUT2 | UART_MCR_DTR),
                .off = (UART_MCR_RTS | UART_MCR_OUT2),
                .send_pulse = send_pulse_homebrew,
                .send_space = send_space_homebrew,
#ifdef CONFIG_LIRC_SERIAL_TRANSMITTER
                .features    = (LIRC_CAN_SET_SEND_DUTY_CYCLE |
                                LIRC_CAN_SET_SEND_CARRIER |
                                LIRC_CAN_SEND_PULSE | LIRC_CAN_REC_MODE2)
#else
                .features    = LIRC_CAN_REC_MODE2
#endif
        },

        [LIRC_IRDEO] = {
                .signal_pin        = UART_MSR_DSR,
                .signal_pin_change = UART_MSR_DDSR,
                .on  = UART_MCR_OUT2,
                .off = (UART_MCR_RTS | UART_MCR_DTR | UART_MCR_OUT2),
                .send_pulse  = send_pulse_irdeo,
                .send_space  = send_space_irdeo,
                .features    = (LIRC_CAN_SET_SEND_DUTY_CYCLE |
                                LIRC_CAN_SEND_PULSE | LIRC_CAN_REC_MODE2)
        },

        [LIRC_IRDEO_REMOTE] = {
                .signal_pin        = UART_MSR_DSR,
                .signal_pin_change = UART_MSR_DDSR,
                .on  = (UART_MCR_RTS | UART_MCR_DTR | UART_MCR_OUT2),
                .off = (UART_MCR_RTS | UART_MCR_DTR | UART_MCR_OUT2),
                .send_pulse  = send_pulse_irdeo,
                .send_space  = send_space_irdeo,
                .features    = (LIRC_CAN_SET_SEND_DUTY_CYCLE |
                                LIRC_CAN_SEND_PULSE | LIRC_CAN_REC_MODE2)
        },

        [LIRC_ANIMAX] = {
                .signal_pin        = UART_MSR_DCD,
                .signal_pin_change = UART_MSR_DDCD,
                .on  = 0,
                .off = (UART_MCR_RTS | UART_MCR_DTR | UART_MCR_OUT2),
                .send_pulse = NULL,
                .send_space = NULL,
                .features   = LIRC_CAN_REC_MODE2
        },

        [LIRC_IGOR] = {
                .signal_pin        = UART_MSR_DSR,
                .signal_pin_change = UART_MSR_DDSR,
                .on  = (UART_MCR_RTS | UART_MCR_OUT2 | UART_MCR_DTR),
                .off = (UART_MCR_RTS | UART_MCR_OUT2),
                .send_pulse = send_pulse_homebrew,
                .send_space = send_space_homebrew,
#ifdef CONFIG_LIRC_SERIAL_TRANSMITTER
                .features    = (LIRC_CAN_SET_SEND_DUTY_CYCLE |
                                LIRC_CAN_SET_SEND_CARRIER |
                                LIRC_CAN_SEND_PULSE | LIRC_CAN_REC_MODE2)
#else
                .features    = LIRC_CAN_REC_MODE2
#endif
        },

#ifdef CONFIG_LIRC_SERIAL_NSLU2
        /*
         * Modified Linksys Network Storage Link USB 2.0 (NSLU2):
         * We receive on CTS of the 2nd serial port (R142,LHS), we
         * transmit with a IR diode between GPIO[1] (green status LED),
         * and ground (Matthias Goebl <matthias.goebl@goebl.net>).
         * See also http://www.nslu2-linux.org for this device
         */
        [LIRC_NSLU2] = {
                .signal_pin        = UART_MSR_CTS,
                .signal_pin_change = UART_MSR_DCTS,
                .on  = (UART_MCR_RTS | UART_MCR_OUT2 | UART_MCR_DTR),
                .off = (UART_MCR_RTS | UART_MCR_OUT2),
                .send_pulse = send_pulse_homebrew,
                .send_space = send_space_homebrew,
#ifdef CONFIG_LIRC_SERIAL_TRANSMITTER
                .features    = (LIRC_CAN_SET_SEND_DUTY_CYCLE |
                                LIRC_CAN_SET_SEND_CARRIER |
                                LIRC_CAN_SEND_PULSE | LIRC_CAN_REC_MODE2)
#else
                .features    = LIRC_CAN_REC_MODE2
#endif
        },
#endif

};

#define RS_ISR_PASS_LIMIT 256

/*
 * A long pulse code from a remote might take up to 300 bytes.  The
 * daemon should read the bytes as soon as they are generated, so take
 * the number of keys you think you can push before the daemon runs
 * and multiply by 300.  The driver will warn you if you overrun this
 * buffer.  If you have a slow computer or non-busmastering IDE disks,
 * maybe you will need to increase this.
 */

/* This MUST be a power of two!  It has to be larger than 1 as well. */

#define RBUF_LEN 256

static struct timeval lasttv = {0, 0};

static struct lirc_buffer rbuf;

static unsigned int freq = 38000;
static unsigned int duty_cycle = 50;

/* Initialized in init_timing_params() */
static unsigned long period;
static unsigned long pulse_width;
static unsigned long space_width;

#if defined(__i386__)
/*
 * From:
 * Linux I/O port programming mini-HOWTO
 * Author: Riku Saikkonen <Riku.Saikkonen@hut.fi>
 * v, 28 December 1997
 *
 * [...]
 * Actually, a port I/O instruction on most ports in the 0-0x3ff range
 * takes almost exactly 1 microsecond, so if you're, for example, using
 * the parallel port directly, just do additional inb()s from that port
 * to delay.
 * [...]
 */
/* transmitter latency 1.5625us 0x1.90 - this figure arrived at from
 * comment above plus trimming to match actual measured frequency.
 * This will be sensitive to cpu speed, though hopefully most of the 1.5us
 * is spent in the uart access.  Still - for reference test machine was a
 * 1.13GHz Athlon system - Steve
 */

/*
 * changed from 400 to 450 as this works better on slower machines;
 * faster machines will use the rdtsc code anyway
 */
#define LIRC_SERIAL_TRANSMITTER_LATENCY 450

#else

/* does anybody have information on other platforms ? */
/* 256 = 1<<8 */
#define LIRC_SERIAL_TRANSMITTER_LATENCY 256

#endif  /* __i386__ */
/*
 * FIXME: should we be using hrtimers instead of this
 * LIRC_SERIAL_TRANSMITTER_LATENCY nonsense?
 */

/* fetch serial input packet (1 byte) from register offset */
static u8 sinp(int offset)
{
        if (iommap != 0)
                /* the register is memory-mapped */
                offset <<= ioshift;

        return inb(io + offset);
}

/* write serial output packet (1 byte) of value to register offset */
static void soutp(int offset, u8 value)
{
        if (iommap != 0)
                /* the register is memory-mapped */
                offset <<= ioshift;

        outb(value, io + offset);
}

static void on(void)
{
#ifdef CONFIG_LIRC_SERIAL_NSLU2
        /*
         * On NSLU2, we put the transmit diode between the output of the green
         * status LED and ground
         */
        if (type == LIRC_NSLU2) {
                gpio_line_set(NSLU2_LED_GRN, IXP4XX_GPIO_LOW);
                return;
        }
#endif
        if (txsense)
                soutp(UART_MCR, hardware[type].off);
        else
                soutp(UART_MCR, hardware[type].on);
}

static void off(void)
{
#ifdef CONFIG_LIRC_SERIAL_NSLU2
        if (type == LIRC_NSLU2) {
                gpio_line_set(NSLU2_LED_GRN, IXP4XX_GPIO_HIGH);
                return;
        }
#endif
        if (txsense)
                soutp(UART_MCR, hardware[type].on);
        else
                soutp(UART_MCR, hardware[type].off);
}

#ifndef MAX_UDELAY_MS
#define MAX_UDELAY_US 5000
#else
#define MAX_UDELAY_US (MAX_UDELAY_MS*1000)
#endif

static void safe_udelay(unsigned long usecs)
{
        while (usecs > MAX_UDELAY_US) {
                udelay(MAX_UDELAY_US);
                usecs -= MAX_UDELAY_US;
        }
        udelay(usecs);
}

#ifdef USE_RDTSC
/*
 * This is an overflow/precision juggle, complicated in that we can't
 * do long long divide in the kernel
 */

/*
 * When we use the rdtsc instruction to measure clocks, we keep the
 * pulse and space widths as clock cycles.  As this is CPU speed
 * dependent, the widths must be calculated in init_port and ioctl
 * time
 */

/* So send_pulse can quickly convert microseconds to clocks */
static unsigned long conv_us_to_clocks;

static int init_timing_params(unsigned int new_duty_cycle,
                unsigned int new_freq)
{
        unsigned long long loops_per_sec, work;

        duty_cycle = new_duty_cycle;
        freq = new_freq;

        loops_per_sec = current_cpu_data.loops_per_jiffy;
        loops_per_sec *= HZ;

        /* How many clocks in a microsecond?, avoiding long long divide */
        work = loops_per_sec;
        work *= 4295;  /* 4295 = 2^32 / 1e6 */
        conv_us_to_clocks = (work >> 32);

        /*
         * Carrier period in clocks, approach good up to 32GHz clock,
         * gets carrier frequency within 8Hz
         */
        period = loops_per_sec >> 3;
        period /= (freq >> 3);

        /* Derive pulse and space from the period */
        pulse_width = period * duty_cycle / 100;
        space_width = period - pulse_width;
        dprintk("in init_timing_params, freq=%d, duty_cycle=%d, "
                "clk/jiffy=%ld, pulse=%ld, space=%ld, "
                "conv_us_to_clocks=%ld\n",
                freq, duty_cycle, current_cpu_data.loops_per_jiffy,
                pulse_width, space_width, conv_us_to_clocks);
        return 0;
}
#else /* ! USE_RDTSC */
static int init_timing_params(unsigned int new_duty_cycle,
                unsigned int new_freq)
{
/*
 * period, pulse/space width are kept with 8 binary places -
 * IE multiplied by 256.
 */
        if (256 * 1000000L / new_freq * new_duty_cycle / 100 <=
            LIRC_SERIAL_TRANSMITTER_LATENCY)
                return -EINVAL;
        if (256 * 1000000L / new_freq * (100 - new_duty_cycle) / 100 <=
            LIRC_SERIAL_TRANSMITTER_LATENCY)
                return -EINVAL;
        duty_cycle = new_duty_cycle;
        freq = new_freq;
        period = 256 * 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;
}
#endif /* USE_RDTSC */


/* return value: space length delta */

static long send_pulse_irdeo(unsigned long length)
{
        long rawbits, ret;
        int i;
        unsigned char output;
        unsigned char chunk, shifted;

        /* how many bits have to be sent ? */
        rawbits = length * 1152 / 10000;
        if (duty_cycle > 50)
                chunk = 3;
        else
                chunk = 1;
        for (i = 0, output = 0x7f; rawbits > 0; rawbits -= 3) {
                shifted = chunk << (i * 3);
                shifted >>= 1;
                output &= (~shifted);
                i++;
                if (i == 3) {
                        soutp(UART_TX, output);
                        while (!(sinp(UART_LSR) & UART_LSR_THRE))
                                ;
                        output = 0x7f;
                        i = 0;
                }
        }
        if (i != 0) {
                soutp(UART_TX, output);
                while (!(sinp(UART_LSR) & UART_LSR_TEMT))
                        ;
        }

        if (i == 0)
                ret = (-rawbits) * 10000 / 1152;
        else
                ret = (3 - i) * 3 * 10000 / 1152 + (-rawbits) * 10000 / 1152;

        return ret;
}

#ifdef USE_RDTSC
/* Version that uses Pentium rdtsc instruction to measure clocks */

/*
 * This version does sub-microsecond timing using rdtsc instruction,
 * and does away with the fudged LIRC_SERIAL_TRANSMITTER_LATENCY
 * Implicitly i586 architecture...  - Steve
 */

static long send_pulse_homebrew_softcarrier(unsigned long length)
{
        int flag;
        unsigned long target, start, now;

        /* Get going quick as we can */
        rdtscl(start);
        on();
        /* Convert length from microseconds to clocks */
        length *= conv_us_to_clocks;
        /* And loop till time is up - flipping at right intervals */
        now = start;
        target = pulse_width;
        flag = 1;
        /*
         * FIXME: This looks like a hard busy wait, without even an occasional,
         * polite, cpu_relax() call.  There's got to be a better way?
         *
         * The i2c code has the result of a lot of bit-banging work, I wonder if
         * there's something there which could be helpful here.
         */
        while ((now - start) < length) {
                /* Delay till flip time */
                do {
                        rdtscl(now);
                } while ((now - start) < target);

                /* flip */
                if (flag) {
                        rdtscl(now);
                        off();
                        target += space_width;
                } else {
                        rdtscl(now); on();
                        target += pulse_width;
                }
                flag = !flag;
        }
        rdtscl(now);
        return ((now - start) - length) / conv_us_to_clocks;
}
#else /* ! USE_RDTSC */
/* Version using udelay() */

/*
 * here we use fixed point arithmetic, with 8
 * fractional bits.  that gets us within 0.1% or so of the right average
 * frequency, albeit with some jitter in pulse length - Steve
 */

/* To match 8 fractional bits used for pulse/space length */

static long send_pulse_homebrew_softcarrier(unsigned long length)
{
        int flag;
        unsigned long actual, target, d;
        length <<= 8;

        actual = 0; target = 0; flag = 0;
        while (actual < length) {
                if (flag) {
                        off();
                        target += space_width;
                } else {
                        on();
                        target += pulse_width;
                }
                d = (target - actual -
                     LIRC_SERIAL_TRANSMITTER_LATENCY + 128) >> 8;
                /*
                 * Note - we've checked in ioctl that the pulse/space
                 * widths are big enough so that d is > 0
                 */
                udelay(d);
                actual += (d << 8) + LIRC_SERIAL_TRANSMITTER_LATENCY;
                flag = !flag;
        }
        return (actual-length) >> 8;
}
#endif /* USE_RDTSC */

static long send_pulse_homebrew(unsigned long length)
{
        if (length <= 0)
                return 0;

        if (softcarrier)
                return send_pulse_homebrew_softcarrier(length);
        else {
                on();
                safe_udelay(length);
                return 0;
        }
}

static void send_space_irdeo(long length)
{
        if (length <= 0)
                return;

        safe_udelay(length);
}

static void send_space_homebrew(long length)
{
        off();
        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 timeval tv;
        int counter, dcd;
        u8 status;
        long deltv;
        int data;
        static int last_dcd = -1;

        if ((sinp(UART_IIR) & UART_IIR_NO_INT)) {
                /* not our interrupt */
                return IRQ_NONE;
        }

        counter = 0;
        do {
                counter++;
                status = sinp(UART_MSR);
                if (counter > RS_ISR_PASS_LIMIT) {
                        printk(KERN_WARNING LIRC_DRIVER_NAME ": AIEEEE: "
                               "We're caught!\n");
                        break;
                }
                if ((status & hardware[type].signal_pin_change)
                    && sense != -1) {
                        /* get current time */
                        do_gettimeofday(&tv);

                        /* New mode, written by Trent Piepho
                           <xyzzy@u.washington.edu>. */

                        /*
                         * The old format was not very portable.
                         * We now use an int to pass pulses
                         * and spaces to user space.
                         *
                         * If PULSE_BIT is set a pulse has been
                         * received, otherwise a space has been
                         * received.  The driver needs to know if your
                         * receiver is active high or active low, or
                         * the space/pulse sense could be
                         * inverted. The bits denoted by PULSE_MASK are
                         * the length in microseconds. Lengths greater
                         * than or equal to 16 seconds are clamped to
                         * PULSE_MASK.  All other bits are unused.
                         * This is a much simpler interface for user
                         * programs, as well as eliminating "out of
                         * phase" errors with space/pulse
                         * autodetection.
                         */

                        /* calc time since last interrupt in microseconds */
                        dcd = (status & hardware[type].signal_pin) ? 1 : 0;

                        if (dcd == last_dcd) {
                                printk(KERN_WARNING LIRC_DRIVER_NAME
                                ": ignoring spike: %d %d %lx %lx %lx %lx\n",
                                dcd, sense,
                                tv.tv_sec, lasttv.tv_sec,
                                tv.tv_usec, lasttv.tv_usec);
                                continue;
                        }

                        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",
                                       dcd, 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 (!(dcd^sense)) {
                                        /* sanity check */
                                        printk(KERN_WARNING LIRC_DRIVER_NAME
                                               ": AIEEEE: "
                                               "%d %d %lx %lx %lx %lx\n",
                                               dcd, 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(dcd^sense ? data : (data|PULSE_BIT));
                        lasttv = tv;
                        last_dcd = dcd;
                        wake_up_interruptible(&rbuf.wait_poll);
                }
        } while (!(sinp(UART_IIR) & UART_IIR_NO_INT)); /* still pending ? */
        return IRQ_HANDLED;
}


static int hardware_init_port(void)
{
        u8 scratch, scratch2, scratch3;

        /*
         * This is a simple port existence test, borrowed from the autoconfig
         * function in drivers/serial/8250.c
         */
        scratch = sinp(UART_IER);
        soutp(UART_IER, 0);
#ifdef __i386__
        outb(0xff, 0x080);
#endif
        scratch2 = sinp(UART_IER) & 0x0f;
        soutp(UART_IER, 0x0f);
#ifdef __i386__
        outb(0x00, 0x080);
#endif
        scratch3 = sinp(UART_IER) & 0x0f;
        soutp(UART_IER, scratch);
        if (scratch2 != 0 || scratch3 != 0x0f) {
                /* we fail, there's nothing here */
                printk(KERN_ERR LIRC_DRIVER_NAME ": port existence test "
                       "failed, cannot continue\n");
                return -EINVAL;
        }



        /* Set DLAB 0. */
        soutp(UART_LCR, sinp(UART_LCR) & (~UART_LCR_DLAB));

        /* First of all, disable all interrupts */
        soutp(UART_IER, sinp(UART_IER) &
              (~(UART_IER_MSI|UART_IER_RLSI|UART_IER_THRI|UART_IER_RDI)));

        /* Clear registers. */
        sinp(UART_LSR);
        sinp(UART_RX);
        sinp(UART_IIR);
        sinp(UART_MSR);

#ifdef CONFIG_LIRC_SERIAL_NSLU2
        if (type == LIRC_NSLU2) {
                /* Setup NSLU2 UART */

                /* Enable UART */
                soutp(UART_IER, sinp(UART_IER) | UART_IE_IXP42X_UUE);
                /* Disable Receiver data Time out interrupt */
                soutp(UART_IER, sinp(UART_IER) & ~UART_IE_IXP42X_RTOIE);
                /* set out2 = interrupt unmask; off() doesn't set MCR
                   on NSLU2 */
                soutp(UART_MCR, UART_MCR_RTS|UART_MCR_OUT2);
        }
#endif

        /* Set line for power source */
        off();

        /* Clear registers again to be sure. */
        sinp(UART_LSR);
        sinp(UART_RX);
        sinp(UART_IIR);
        sinp(UART_MSR);

        switch (type) {
        case LIRC_IRDEO:
        case LIRC_IRDEO_REMOTE:
                /* setup port to 7N1 @ 115200 Baud */
                /* 7N1+start = 9 bits at 115200 ~ 3 bits at 38kHz */

                /* Set DLAB 1. */
                soutp(UART_LCR, sinp(UART_LCR) | UART_LCR_DLAB);
                /* Set divisor to 1 => 115200 Baud */
                soutp(UART_DLM, 0);
                soutp(UART_DLL, 1);
                /* Set DLAB 0 +  7N1 */
                soutp(UART_LCR, UART_LCR_WLEN7);
                /* THR interrupt already disabled at this point */
                break;
        default:
                break;
        }

        return 0;
}

static int init_port(void)
{
        int i, nlow, nhigh;

        /* Reserve io region. */
        /*
         * Future MMAP-Developers: Attention!
         * For memory mapped I/O you *might* need to use ioremap() first,
         * for the NSLU2 it's done in boot code.
         */
        if (((iommap != 0)
             && (request_mem_region(iommap, 8 << ioshift,
                                    LIRC_DRIVER_NAME) == NULL))
           || ((iommap == 0)
               && (request_region(io, 8, LIRC_DRIVER_NAME) == NULL))) {
                printk(KERN_ERR  LIRC_DRIVER_NAME
                       ": port %04x already in use\n", io);
                printk(KERN_WARNING LIRC_DRIVER_NAME
                       ": use 'setserial /dev/ttySX uart none'\n");
                printk(KERN_WARNING LIRC_DRIVER_NAME
                       ": or compile the serial port driver as module and\n");
                printk(KERN_WARNING LIRC_DRIVER_NAME
                       ": make sure this module is loaded first\n");
                return -EBUSY;
        }

        if (hardware_init_port() < 0)
                return -EINVAL;

        /* Initialize pulse/space widths */
        init_timing_params(duty_cycle, freq);

        /* 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 (sinp(UART_MSR) & hardware[type].signal_pin)
                                nlow++;
                        else
                                nhigh++;
                        msleep(40);
                }
                sense = (nlow >= nhigh ? 1 : 0);
                printk(KERN_INFO LIRC_DRIVER_NAME  ": auto-detected active "
                       "%s receiver\n", sense ? "low" : "high");
        } else
                printk(KERN_INFO LIRC_DRIVER_NAME  ": Manually using active "
                       "%s receiver\n", sense ? "low" : "high");

        return 0;
}

static int set_use_inc(void *data)
{
        int result;
        unsigned long flags;

        /* initialize timestamp */
        do_gettimeofday(&lasttv);

        result = request_irq(irq, irq_handler,
                             IRQF_DISABLED | (share_irq ? IRQF_SHARED : 0),
                             LIRC_DRIVER_NAME, (void *)&hardware);

        switch (result) {
        case -EBUSY:
                printk(KERN_ERR LIRC_DRIVER_NAME ": IRQ %d busy\n", irq);
                return -EBUSY;
        case -EINVAL:
                printk(KERN_ERR LIRC_DRIVER_NAME
                       ": Bad irq number or handler\n");
                return -EINVAL;
        default:
                dprintk("Interrupt %d, port %04x obtained\n", irq, io);
                break;
        };

        spin_lock_irqsave(&hardware[type].lock, flags);

        /* Set DLAB 0. */
        soutp(UART_LCR, sinp(UART_LCR) & (~UART_LCR_DLAB));

        soutp(UART_IER, sinp(UART_IER)|UART_IER_MSI);

        spin_unlock_irqrestore(&hardware[type].lock, flags);

        return 0;
}

static void set_use_dec(void *data)
{       unsigned long flags;

        spin_lock_irqsave(&hardware[type].lock, flags);

        /* Set DLAB 0. */
        soutp(UART_LCR, sinp(UART_LCR) & (~UART_LCR_DLAB));

        /* First of all, disable all interrupts */
        soutp(UART_IER, sinp(UART_IER) &
              (~(UART_IER_MSI|UART_IER_RLSI|UART_IER_THRI|UART_IER_RDI)));
        spin_unlock_irqrestore(&hardware[type].lock, flags);

        free_irq(irq, (void *)&hardware);

        dprintk("freed IRQ %d\n", irq);
}

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;

        if (!(hardware[type].features & LIRC_CAN_SEND_PULSE))
                return -EBADF;

        count = n / sizeof(int);
        if (n % sizeof(int) || count % 2 == 0)
                return -EINVAL;
        wbuf = memdup_user(buf, n);
        if (PTR_ERR(wbuf))
                return PTR_ERR(wbuf);
        spin_lock_irqsave(&hardware[type].lock, flags);
        if (type == LIRC_IRDEO) {
                /* DTR, RTS down */
                on();
        }
        for (i = 0; i < count; i++) {
                if (i%2)
                        hardware[type].send_space(wbuf[i] - delta);
                else
                        delta = hardware[type].send_pulse(wbuf[i]);
        }
        off();
        spin_unlock_irqrestore(&hardware[type].lock, flags);
        return n;
}

static long lirc_ioctl(struct file *filep, unsigned int cmd, unsigned long arg)
{
        int result;
        unsigned long value;
        unsigned int ivalue;

        switch (cmd) {
        case LIRC_GET_SEND_MODE:
                if (!(hardware[type].features&LIRC_CAN_SEND_MASK))
                        return -ENOIOCTLCMD;

                result = put_user(LIRC_SEND2MODE
                                  (hardware[type].features&LIRC_CAN_SEND_MASK),
                                  (unsigned long *) arg);
                if (result)
                        return result;
                break;

        case LIRC_SET_SEND_MODE:
                if (!(hardware[type].features&LIRC_CAN_SEND_MASK))
                        return -ENOIOCTLCMD;

                result = get_user(value, (unsigned long *) 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");
                if (!(hardware[type].features&LIRC_CAN_SET_SEND_DUTY_CYCLE))
                        return -ENOIOCTLCMD;

                result = get_user(ivalue, (unsigned int *) arg);
                if (result)
                        return result;
                if (ivalue <= 0 || ivalue > 100)
                        return -EINVAL;
                return init_timing_params(ivalue, freq);
                break;

        case LIRC_SET_SEND_CARRIER:
                dprintk("SET_SEND_CARRIER\n");
                if (!(hardware[type].features&LIRC_CAN_SET_SEND_CARRIER))
                        return -ENOIOCTLCMD;

                result = get_user(ivalue, (unsigned int *) arg);
                if (result)
                        return result;
                if (ivalue > 500000 || ivalue < 20000)
                        return -EINVAL;
                return init_timing_params(duty_cycle, ivalue);
                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_device *lirc_serial_dev;

static int __devinit lirc_serial_probe(struct platform_device *dev)
{
        return 0;
}

static int __devexit lirc_serial_remove(struct platform_device *dev)
{
        return 0;
}

static int lirc_serial_suspend(struct platform_device *dev,
                               pm_message_t state)
{
        /* Set DLAB 0. */
        soutp(UART_LCR, sinp(UART_LCR) & (~UART_LCR_DLAB));

        /* Disable all interrupts */
        soutp(UART_IER, sinp(UART_IER) &
              (~(UART_IER_MSI|UART_IER_RLSI|UART_IER_THRI|UART_IER_RDI)));

        /* Clear registers. */
        sinp(UART_LSR);
        sinp(UART_RX);
        sinp(UART_IIR);
        sinp(UART_MSR);

        return 0;
}

/* twisty maze... need a forward-declaration here... */
static void lirc_serial_exit(void);

static int lirc_serial_resume(struct platform_device *dev)
{
        unsigned long flags;

        if (hardware_init_port() < 0) {
                lirc_serial_exit();
                return -EINVAL;
        }

        spin_lock_irqsave(&hardware[type].lock, flags);
        /* Enable Interrupt */
        do_gettimeofday(&lasttv);
        soutp(UART_IER, sinp(UART_IER)|UART_IER_MSI);
        off();

        lirc_buffer_clear(&rbuf);

        spin_unlock_irqrestore(&hardware[type].lock, flags);

        return 0;
}

static struct platform_driver lirc_serial_driver = {
        .probe          = lirc_serial_probe,
        .remove         = __devexit_p(lirc_serial_remove),
        .suspend        = lirc_serial_suspend,
        .resume         = lirc_serial_resume,
        .driver         = {
                .name   = "lirc_serial",
                .owner  = THIS_MODULE,
        },
};

static int __init lirc_serial_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_serial_driver);
        if (result) {
                printk("lirc register returned %d\n", result);
                goto exit_buffer_free;
        }

        lirc_serial_dev = platform_device_alloc("lirc_serial", 0);
        if (!lirc_serial_dev) {
                result = -ENOMEM;
                goto exit_driver_unregister;
        }

        result = platform_device_add(lirc_serial_dev);
        if (result)
                goto exit_device_put;

        return 0;

exit_device_put:
        platform_device_put(lirc_serial_dev);
exit_driver_unregister:
        platform_driver_unregister(&lirc_serial_driver);
exit_buffer_free:
        lirc_buffer_free(&rbuf);
        return result;
}

static void lirc_serial_exit(void)
{
        platform_device_unregister(lirc_serial_dev);
        platform_driver_unregister(&lirc_serial_driver);
        lirc_buffer_free(&rbuf);
}

static int __init lirc_serial_init_module(void)
{
        int result;

        result = lirc_serial_init();
        if (result)
                return result;

        switch (type) {
        case LIRC_HOMEBREW:
        case LIRC_IRDEO:
        case LIRC_IRDEO_REMOTE:
        case LIRC_ANIMAX:
        case LIRC_IGOR:
                /* if nothing specified, use ttyS0/com1 and irq 4 */
                io = io ? io : 0x3f8;
                irq = irq ? irq : 4;
                break;
#ifdef CONFIG_LIRC_SERIAL_NSLU2
        case LIRC_NSLU2:
                io = io ? io : IRQ_IXP4XX_UART2;
                irq = irq ? irq : (IXP4XX_UART2_BASE_VIRT + REG_OFFSET);
                iommap = iommap ? iommap : IXP4XX_UART2_BASE_PHYS;
                ioshift = ioshift ? ioshift : 2;
                break;
#endif
        default:
                result = -EINVAL;
                goto exit_serial_exit;
        }
        if (!softcarrier) {
                switch (type) {
                case LIRC_HOMEBREW:
                case LIRC_IGOR:
#ifdef CONFIG_LIRC_SERIAL_NSLU2
                case LIRC_NSLU2:
#endif
                        hardware[type].features &=
                                ~(LIRC_CAN_SET_SEND_DUTY_CYCLE|
                                  LIRC_CAN_SET_SEND_CARRIER);
                        break;
                }
        }

        result = init_port();
        if (result < 0)
                goto exit_serial_exit;
        driver.features = hardware[type].features;
        driver.dev = &lirc_serial_dev->dev;
        driver.minor = lirc_register_driver(&driver);
        if (driver.minor < 0) {
                printk(KERN_ERR  LIRC_DRIVER_NAME
                       ": register_chrdev failed!\n");
                result = -EIO;
                goto exit_release;
        }
        return 0;
exit_release:
        release_region(io, 8);
exit_serial_exit:
        lirc_serial_exit();
        return result;
}

static void __exit lirc_serial_exit_module(void)
{
        lirc_serial_exit();
        if (iommap != 0)
                release_mem_region(iommap, 8 << ioshift);
        else
                release_region(io, 8);
        lirc_unregister_driver(driver.minor);
        dprintk("cleaned up module\n");
}


module_init(lirc_serial_init_module);
module_exit(lirc_serial_exit_module);

MODULE_DESCRIPTION("Infra-red receiver driver for serial ports.");
MODULE_AUTHOR("Ralph Metzler, Trent Piepho, Ben Pfaff, "
              "Christoph Bartelmus, Andrei Tanas");
MODULE_LICENSE("GPL");

module_param(type, int, S_IRUGO);
MODULE_PARM_DESC(type, "Hardware type (0 = home-brew, 1 = IRdeo,"
                 " 2 = IRdeo Remote, 3 = AnimaX, 4 = IgorPlug,"
                 " 5 = NSLU2 RX:CTS2/TX:GreenLED)");

module_param(io, int, S_IRUGO);
MODULE_PARM_DESC(io, "I/O address base (0x3f8 or 0x2f8)");

/* some architectures (e.g. intel xscale) have memory mapped registers */
module_param(iommap, bool, S_IRUGO);
MODULE_PARM_DESC(iommap, "physical base for memory mapped I/O"
                " (0 = no memory mapped io)");

/*
 * some architectures (e.g. intel xscale) align the 8bit serial registers
 * on 32bit word boundaries.
 * See linux-kernel/serial/8250.c serial_in()/out()
 */
module_param(ioshift, int, S_IRUGO);
MODULE_PARM_DESC(ioshift, "shift I/O register offset (0 = no shift)");

module_param(irq, int, S_IRUGO);
MODULE_PARM_DESC(irq, "Interrupt (4 or 3)");

module_param(share_irq, bool, S_IRUGO);
MODULE_PARM_DESC(share_irq, "Share interrupts (0 = off, 1 = on)");

module_param(sense, bool, S_IRUGO);
MODULE_PARM_DESC(sense, "Override autodetection of IR receiver circuit"
                 " (0 = active high, 1 = active low )");

#ifdef CONFIG_LIRC_SERIAL_TRANSMITTER
module_param(txsense, bool, S_IRUGO);
MODULE_PARM_DESC(txsense, "Sense of transmitter circuit"
                 " (0 = active high, 1 = active low )");
#endif

module_param(softcarrier, bool, S_IRUGO);
MODULE_PARM_DESC(softcarrier, "Software carrier (0 = off, 1 = on, default on)");

module_param(debug, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(debug, "Enable debugging messages");