lirc_serial.c

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/*
 * 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 <[email protected]>
 * Copyright (C) 1998 Trent Piepho <[email protected]>
 * Copyright (C) 1998 Ben Pfaff <[email protected]>
 * Copyright (C) 1999 Christoph Bartelmus <[email protected]>
 * Copyright (C) 2007 Andrei Tanas <[email protected]> (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 <[email protected]>  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 <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 bool iommap;
static int ioshift;
static bool softcarrier = 1;
static bool share_irq;
static bool debug;
static int sense = -1;  /* -1 = auto, 0 = active high, 1 = active low */
static bool 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] = {
        .lock = __SPIN_LOCK_UNLOCKED(hardware[LIRC_HOMEBREW].lock),
        .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] = {
        .lock = __SPIN_LOCK_UNLOCKED(hardware[LIRC_IRDEO].lock),
        .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] = {
        .lock = __SPIN_LOCK_UNLOCKED(hardware[LIRC_IRDEO_REMOTE].lock),
        .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] = {
        .lock = __SPIN_LOCK_UNLOCKED(hardware[LIRC_ANIMAX].lock),
        .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] = {
        .lock = __SPIN_LOCK_UNLOCKED(hardware[LIRC_IGOR].lock),
        .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 <[email protected]>).
     * See also http://www.nslu2-linux.org for this device
     */
    [LIRC_NSLU2] = {
        .lock = __SPIN_LOCK_UNLOCKED(hardware[LIRC_NSLU2].lock),
        .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 <[email protected]>
 * 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)
{
    __u64 loops_per_sec, work;

    duty_cycle = new_duty_cycle;
    freq = new_freq;

    loops_per_sec = __this_cpu_read(cpu.info.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, __this_cpu_read(cpu_info.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
               <[email protected]>. */

            /*
             * 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 -ENODEV;
    }



    /* 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 __devinit lirc_serial_probe(struct platform_device *dev)
{
    int i, nlow, nhigh, result;

    result = request_irq(irq, irq_handler,
                 (share_irq ? IRQF_SHARED : 0),
                 LIRC_DRIVER_NAME, (void *)&hardware);
    if (result < 0) {
        if (result == -EBUSY)
            printk(KERN_ERR LIRC_DRIVER_NAME ": IRQ %d busy\n",
                   irq);
        else if (result == -EINVAL)
            printk(KERN_ERR LIRC_DRIVER_NAME
                   ": Bad irq number or handler\n");
        return result;
    }

    /* 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");
        result = -EBUSY;
        goto exit_free_irq;
    }

    result = hardware_init_port();
    if (result < 0)
        goto exit_release_region;

    /* 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");

    dprintk("Interrupt %d, port %04x obtained\n", irq, io);
    return 0;

exit_release_region:
    if (iommap != 0)
        release_mem_region(iommap, 8 << ioshift);
    else
        release_region(io, 8);
exit_free_irq:
    free_irq(irq, (void *)&hardware);

    return result;
}

static int __devexit lirc_serial_remove(struct platform_device *dev)
{
    free_irq(irq, (void *)&hardware);

    if (iommap != 0)
        release_mem_region(iommap, 8 << ioshift);
    else
        release_region(io, 8);

    return 0;
}

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

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

    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);
}

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 -EPERM;

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

        result = put_user(LIRC_SEND2MODE
                  (hardware[type].features&LIRC_CAN_SEND_MASK),
                  (__u32 *) 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, (__u32 *) arg);
        if (result)
            return result;
        /* only LIRC_MODE_PULSE supported */
        if (value != LIRC_MODE_PULSE)
            return -EINVAL;
        break;

    case LIRC_GET_LENGTH:
        return -ENOIOCTLCMD;
        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(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");
        if (!(hardware[type].features&LIRC_CAN_SET_SEND_CARRIER))
            return -ENOIOCTLCMD;

        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,
#ifdef CONFIG_COMPAT
    .compat_ioctl   = lirc_ioctl,
#endif
    .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 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;
    int result;

    result = hardware_init_port();
    if (result < 0)
        return result;

    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 result;

    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;

    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:
        return -EINVAL;
    }
    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 = lirc_serial_init();
    if (result)
        return result;

    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");
        lirc_serial_exit();
        return driver.minor;
    }
    return 0;
}

static void __exit lirc_serial_exit_module(void)
{
    lirc_unregister_driver(driver.minor);
    lirc_serial_exit();
    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/drivers/tty/serial/8250/8250.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");