hil_mlc.c

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/*
 * HIL MLC state machine and serio interface driver
 *
 * Copyright (c) 2001 Brian S. Julin
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions, and the following disclaimer,
 *    without modification.
 * 2. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL").
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 *
 * References:
 * HP-HIL Technical Reference Manual.  Hewlett Packard Product No. 45918A
 *
 *
 *  Driver theory of operation:
 *
 *  Some access methods and an ISR is defined by the sub-driver
 *  (e.g. hp_sdc_mlc.c).  These methods are expected to provide a
 *  few bits of logic in addition to raw access to the HIL MLC,
 *  specifically, the ISR, which is entirely registered by the
 *  sub-driver and invoked directly, must check for record
 *  termination or packet match, at which point a semaphore must
 *  be cleared and then the hil_mlcs_tasklet must be scheduled.
 *
 *  The hil_mlcs_tasklet processes the state machine for all MLCs
 *  each time it runs, checking each MLC's progress at the current
 *  node in the state machine, and moving the MLC to subsequent nodes
 *  in the state machine when appropriate.  It will reschedule
 *  itself if output is pending.  (This rescheduling should be replaced
 *  at some point with a sub-driver-specific mechanism.)
 *
 *  A timer task prods the tasklet once per second to prevent
 *  hangups when attached devices do not return expected data
 *  and to initiate probes of the loop for new devices.
 */

#include <linux/hil_mlc.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <linux/timer.h>
#include <linux/list.h>

MODULE_AUTHOR("Brian S. Julin <[email protected]>");
MODULE_DESCRIPTION("HIL MLC serio");
MODULE_LICENSE("Dual BSD/GPL");

EXPORT_SYMBOL(hil_mlc_register);
EXPORT_SYMBOL(hil_mlc_unregister);

#define PREFIX "HIL MLC: "

static LIST_HEAD(hil_mlcs);
static DEFINE_RWLOCK(hil_mlcs_lock);
static struct timer_list    hil_mlcs_kicker;
static int          hil_mlcs_probe;

static void hil_mlcs_process(unsigned long unused);
static DECLARE_TASKLET_DISABLED(hil_mlcs_tasklet, hil_mlcs_process, 0);


/* #define HIL_MLC_DEBUG */

/********************** Device info/instance management **********************/

static void hil_mlc_clear_di_map(hil_mlc *mlc, int val)
{
    int j;

    for (j = val; j < 7 ; j++)
        mlc->di_map[j] = -1;
}

static void hil_mlc_clear_di_scratch(hil_mlc *mlc)
{
    memset(&mlc->di_scratch, 0, sizeof(mlc->di_scratch));
}

static void hil_mlc_copy_di_scratch(hil_mlc *mlc, int idx)
{
    memcpy(&mlc->di[idx], &mlc->di_scratch, sizeof(mlc->di_scratch));
}

static int hil_mlc_match_di_scratch(hil_mlc *mlc)
{
    int idx;

    for (idx = 0; idx < HIL_MLC_DEVMEM; idx++) {
        int j, found = 0;

        /* In-use slots are not eligible. */
        for (j = 0; j < 7 ; j++)
            if (mlc->di_map[j] == idx)
                found++;

        if (found)
            continue;

        if (!memcmp(mlc->di + idx, &mlc->di_scratch,
                sizeof(mlc->di_scratch)))
            break;
    }
    return idx >= HIL_MLC_DEVMEM ? -1 : idx;
}

static int hil_mlc_find_free_di(hil_mlc *mlc)
{
    int idx;

    /* TODO: Pick all-zero slots first, failing that,
     * randomize the slot picked among those eligible.
     */
    for (idx = 0; idx < HIL_MLC_DEVMEM; idx++) {
        int j, found = 0;

        for (j = 0; j < 7 ; j++)
            if (mlc->di_map[j] == idx)
                found++;

        if (!found)
            break;
    }

    return idx; /* Note: It is guaranteed at least one above will match */
}

static inline void hil_mlc_clean_serio_map(hil_mlc *mlc)
{
    int idx;

    for (idx = 0; idx < HIL_MLC_DEVMEM; idx++) {
        int j, found = 0;

        for (j = 0; j < 7 ; j++)
            if (mlc->di_map[j] == idx)
                found++;

        if (!found)
            mlc->serio_map[idx].di_revmap = -1;
    }
}

static void hil_mlc_send_polls(hil_mlc *mlc)
{
    int did, i, cnt;
    struct serio *serio;
    struct serio_driver *drv;

    i = cnt = 0;
    did = (mlc->ipacket[0] & HIL_PKT_ADDR_MASK) >> 8;
    serio = did ? mlc->serio[mlc->di_map[did - 1]] : NULL;
    drv = (serio != NULL) ? serio->drv : NULL;

    while (mlc->icount < 15 - i) {
        hil_packet p;

        p = mlc->ipacket[i];
        if (did != (p & HIL_PKT_ADDR_MASK) >> 8) {
            if (drv && drv->interrupt) {
                drv->interrupt(serio, 0, 0);
                drv->interrupt(serio, HIL_ERR_INT >> 16, 0);
                drv->interrupt(serio, HIL_PKT_CMD >> 8,  0);
                drv->interrupt(serio, HIL_CMD_POL + cnt, 0);
            }

            did = (p & HIL_PKT_ADDR_MASK) >> 8;
            serio = did ? mlc->serio[mlc->di_map[did-1]] : NULL;
            drv = (serio != NULL) ? serio->drv : NULL;
            cnt = 0;
        }

        cnt++;
        i++;

        if (drv && drv->interrupt) {
            drv->interrupt(serio, (p >> 24), 0);
            drv->interrupt(serio, (p >> 16) & 0xff, 0);
            drv->interrupt(serio, (p >> 8) & ~HIL_PKT_ADDR_MASK, 0);
            drv->interrupt(serio, p & 0xff, 0);
        }
    }
}

/*************************** State engine *********************************/

#define HILSEN_SCHED    0x000100    /* Schedule the tasklet     */
#define HILSEN_BREAK    0x000200    /* Wait until next pass     */
#define HILSEN_UP   0x000400    /* relative node#, decrement    */
#define HILSEN_DOWN 0x000800    /* relative node#, increment    */
#define HILSEN_FOLLOW   0x001000    /* use retval as next node# */

#define HILSEN_MASK 0x0000ff
#define HILSEN_START    0
#define HILSEN_RESTART  1
#define HILSEN_DHR  9
#define HILSEN_DHR2 10
#define HILSEN_IFC  14
#define HILSEN_HEAL0    16
#define HILSEN_HEAL 18
#define HILSEN_ACF      21
#define HILSEN_ACF2 22
#define HILSEN_DISC0    25
#define HILSEN_DISC 27
#define HILSEN_MATCH    40
#define HILSEN_OPERATE  41
#define HILSEN_PROBE    44
#define HILSEN_DSR  52
#define HILSEN_REPOLL   55
#define HILSEN_IFCACF   58
#define HILSEN_END  60

#define HILSEN_NEXT (HILSEN_DOWN | 1)
#define HILSEN_SAME (HILSEN_DOWN | 0)
#define HILSEN_LAST (HILSEN_UP | 1)

#define HILSEN_DOZE (HILSEN_SAME | HILSEN_SCHED | HILSEN_BREAK)
#define HILSEN_SLEEP    (HILSEN_SAME | HILSEN_BREAK)

static int hilse_match(hil_mlc *mlc, int unused)
{
    int rc;

    rc = hil_mlc_match_di_scratch(mlc);
    if (rc == -1) {
        rc = hil_mlc_find_free_di(mlc);
        if (rc == -1)
            goto err;

#ifdef HIL_MLC_DEBUG
        printk(KERN_DEBUG PREFIX "new in slot %i\n", rc);
#endif
        hil_mlc_copy_di_scratch(mlc, rc);
        mlc->di_map[mlc->ddi] = rc;
        mlc->serio_map[rc].di_revmap = mlc->ddi;
        hil_mlc_clean_serio_map(mlc);
        serio_rescan(mlc->serio[rc]);
        return -1;
    }

    mlc->di_map[mlc->ddi] = rc;
#ifdef HIL_MLC_DEBUG
    printk(KERN_DEBUG PREFIX "same in slot %i\n", rc);
#endif
    mlc->serio_map[rc].di_revmap = mlc->ddi;
    hil_mlc_clean_serio_map(mlc);
    return 0;

 err:
    printk(KERN_ERR PREFIX "Residual device slots exhausted, close some serios!\n");
    return 1;
}

/* An LCV used to prevent runaway loops, forces 5 second sleep when reset. */
static int hilse_init_lcv(hil_mlc *mlc, int unused)
{
    struct timeval tv;

    do_gettimeofday(&tv);

    if (mlc->lcv && (tv.tv_sec - mlc->lcv_tv.tv_sec) < 5)
        return -1;

    mlc->lcv_tv = tv;
    mlc->lcv = 0;

    return 0;
}

static int hilse_inc_lcv(hil_mlc *mlc, int lim)
{
    return mlc->lcv++ >= lim ? -1 : 0;
}

#if 0
static int hilse_set_lcv(hil_mlc *mlc, int val)
{
    mlc->lcv = val;

    return 0;
}
#endif

/* Management of the discovered device index (zero based, -1 means no devs) */
static int hilse_set_ddi(hil_mlc *mlc, int val)
{
    mlc->ddi = val;
    hil_mlc_clear_di_map(mlc, val + 1);

    return 0;
}

static int hilse_dec_ddi(hil_mlc *mlc, int unused)
{
    mlc->ddi--;
    if (mlc->ddi <= -1) {
        mlc->ddi = -1;
        hil_mlc_clear_di_map(mlc, 0);
        return -1;
    }
    hil_mlc_clear_di_map(mlc, mlc->ddi + 1);

    return 0;
}

static int hilse_inc_ddi(hil_mlc *mlc, int unused)
{
    BUG_ON(mlc->ddi >= 6);
    mlc->ddi++;

    return 0;
}

static int hilse_take_idd(hil_mlc *mlc, int unused)
{
    int i;

    /* Help the state engine:
     * Is this a real IDD response or just an echo?
     *
     * Real IDD response does not start with a command.
     */
    if (mlc->ipacket[0] & HIL_PKT_CMD)
        goto bail;

    /* Should have the command echoed further down. */
    for (i = 1; i < 16; i++) {
        if (((mlc->ipacket[i] & HIL_PKT_ADDR_MASK) ==
             (mlc->ipacket[0] & HIL_PKT_ADDR_MASK)) &&
            (mlc->ipacket[i] & HIL_PKT_CMD) &&
            ((mlc->ipacket[i] & HIL_PKT_DATA_MASK) == HIL_CMD_IDD))
            break;
    }
    if (i > 15)
        goto bail;

    /* And the rest of the packets should still be clear. */
    while (++i < 16)
        if (mlc->ipacket[i])
            break;

    if (i < 16)
        goto bail;

    for (i = 0; i < 16; i++)
        mlc->di_scratch.idd[i] =
            mlc->ipacket[i] & HIL_PKT_DATA_MASK;

    /* Next step is to see if RSC supported */
    if (mlc->di_scratch.idd[1] & HIL_IDD_HEADER_RSC)
        return HILSEN_NEXT;

    if (mlc->di_scratch.idd[1] & HIL_IDD_HEADER_EXD)
        return HILSEN_DOWN | 4;

    return 0;

 bail:
    mlc->ddi--;

    return -1; /* This should send us off to ACF */
}

static int hilse_take_rsc(hil_mlc *mlc, int unused)
{
    int i;

    for (i = 0; i < 16; i++)
        mlc->di_scratch.rsc[i] =
            mlc->ipacket[i] & HIL_PKT_DATA_MASK;

    /* Next step is to see if EXD supported (IDD has already been read) */
    if (mlc->di_scratch.idd[1] & HIL_IDD_HEADER_EXD)
        return HILSEN_NEXT;

    return 0;
}

static int hilse_take_exd(hil_mlc *mlc, int unused)
{
    int i;

    for (i = 0; i < 16; i++)
        mlc->di_scratch.exd[i] =
            mlc->ipacket[i] & HIL_PKT_DATA_MASK;

    /* Next step is to see if RNM supported. */
    if (mlc->di_scratch.exd[0] & HIL_EXD_HEADER_RNM)
        return HILSEN_NEXT;

    return 0;
}

static int hilse_take_rnm(hil_mlc *mlc, int unused)
{
    int i;

    for (i = 0; i < 16; i++)
        mlc->di_scratch.rnm[i] =
            mlc->ipacket[i] & HIL_PKT_DATA_MASK;

    printk(KERN_INFO PREFIX "Device name gotten: %16s\n",
            mlc->di_scratch.rnm);

    return 0;
}

static int hilse_operate(hil_mlc *mlc, int repoll)
{

    if (mlc->opercnt == 0)
        hil_mlcs_probe = 0;
    mlc->opercnt = 1;

    hil_mlc_send_polls(mlc);

    if (!hil_mlcs_probe)
        return 0;
    hil_mlcs_probe = 0;
    mlc->opercnt = 0;
    return 1;
}

#define FUNC(funct, funct_arg, zero_rc, neg_rc, pos_rc) \
{ HILSE_FUNC,       { .func = funct }, funct_arg, zero_rc, neg_rc, pos_rc },
#define OUT(pack) \
{ HILSE_OUT,        { .packet = pack }, 0, HILSEN_NEXT, HILSEN_DOZE, 0 },
#define CTS \
{ HILSE_CTS,        { .packet = 0    }, 0, HILSEN_NEXT | HILSEN_SCHED | HILSEN_BREAK, HILSEN_DOZE, 0 },
#define EXPECT(comp, to, got, got_wrong, timed_out) \
{ HILSE_EXPECT,     { .packet = comp }, to, got, got_wrong, timed_out },
#define EXPECT_LAST(comp, to, got, got_wrong, timed_out) \
{ HILSE_EXPECT_LAST,    { .packet = comp }, to, got, got_wrong, timed_out },
#define EXPECT_DISC(comp, to, got, got_wrong, timed_out) \
{ HILSE_EXPECT_DISC,    { .packet = comp }, to, got, got_wrong, timed_out },
#define IN(to, got, got_error, timed_out) \
{ HILSE_IN,     { .packet = 0    }, to, got, got_error, timed_out },
#define OUT_DISC(pack) \
{ HILSE_OUT_DISC,   { .packet = pack }, 0, 0, 0, 0 },
#define OUT_LAST(pack) \
{ HILSE_OUT_LAST,   { .packet = pack }, 0, 0, 0, 0 },

static const struct hilse_node hil_mlc_se[HILSEN_END] = {

    /* 0  HILSEN_START */
    FUNC(hilse_init_lcv, 0, HILSEN_NEXT,    HILSEN_SLEEP,   0)

    /* 1  HILSEN_RESTART */
    FUNC(hilse_inc_lcv, 10, HILSEN_NEXT,    HILSEN_START,  0)
    OUT(HIL_CTRL_ONLY)          /* Disable APE */
    CTS

#define TEST_PACKET(x) \
(HIL_PKT_CMD | (x << HIL_PKT_ADDR_SHIFT) | x << 4 | x)

    OUT(HIL_DO_ALTER_CTRL | HIL_CTRL_TEST | TEST_PACKET(0x5))
    EXPECT(HIL_ERR_INT | TEST_PACKET(0x5),
           2000,        HILSEN_NEXT,    HILSEN_RESTART, HILSEN_RESTART)
    OUT(HIL_DO_ALTER_CTRL | HIL_CTRL_TEST | TEST_PACKET(0xa))
    EXPECT(HIL_ERR_INT | TEST_PACKET(0xa),
           2000,        HILSEN_NEXT,    HILSEN_RESTART, HILSEN_RESTART)
    OUT(HIL_CTRL_ONLY | 0)          /* Disable test mode */

    /* 9  HILSEN_DHR */
    FUNC(hilse_init_lcv, 0, HILSEN_NEXT,    HILSEN_SLEEP,   0)

    /* 10 HILSEN_DHR2 */
    FUNC(hilse_inc_lcv, 10, HILSEN_NEXT,    HILSEN_START,   0)
    FUNC(hilse_set_ddi, -1, HILSEN_NEXT,    0,      0)
    OUT(HIL_PKT_CMD | HIL_CMD_DHR)
    IN(300000,      HILSEN_DHR2,    HILSEN_DHR2,    HILSEN_NEXT)

    /* 14 HILSEN_IFC */
    OUT(HIL_PKT_CMD | HIL_CMD_IFC)
    EXPECT(HIL_PKT_CMD | HIL_CMD_IFC | HIL_ERR_INT,
           20000,       HILSEN_DISC,    HILSEN_DHR2,    HILSEN_NEXT )

    /* If devices are there, they weren't in PUP or other loopback mode.
     * We're more concerned at this point with restoring operation
     * to devices than discovering new ones, so we try to salvage
     * the loop configuration by closing off the loop.
     */

    /* 16 HILSEN_HEAL0 */
    FUNC(hilse_dec_ddi, 0,  HILSEN_NEXT,    HILSEN_ACF, 0)
    FUNC(hilse_inc_ddi, 0,  HILSEN_NEXT,    0,      0)

    /* 18 HILSEN_HEAL */
    OUT_LAST(HIL_CMD_ELB)
    EXPECT_LAST(HIL_CMD_ELB | HIL_ERR_INT,
            20000,  HILSEN_REPOLL,  HILSEN_DSR, HILSEN_NEXT)
    FUNC(hilse_dec_ddi, 0,  HILSEN_HEAL,    HILSEN_NEXT,    0)

    /* 21 HILSEN_ACF */
    FUNC(hilse_init_lcv, 0, HILSEN_NEXT,    HILSEN_DOZE,    0)

    /* 22 HILSEN_ACF2 */
    FUNC(hilse_inc_lcv, 10, HILSEN_NEXT,    HILSEN_START,   0)
    OUT(HIL_PKT_CMD | HIL_CMD_ACF | 1)
    IN(20000,       HILSEN_NEXT,    HILSEN_DSR, HILSEN_NEXT)

    /* 25 HILSEN_DISC0 */
    OUT_DISC(HIL_PKT_CMD | HIL_CMD_ELB)
    EXPECT_DISC(HIL_PKT_CMD | HIL_CMD_ELB | HIL_ERR_INT,
           20000,       HILSEN_NEXT,    HILSEN_DSR, HILSEN_DSR)

    /* Only enter here if response just received */
    /* 27 HILSEN_DISC */
    OUT_DISC(HIL_PKT_CMD | HIL_CMD_IDD)
    EXPECT_DISC(HIL_PKT_CMD | HIL_CMD_IDD | HIL_ERR_INT,
           20000,       HILSEN_NEXT,    HILSEN_DSR, HILSEN_START)
    FUNC(hilse_inc_ddi,  0, HILSEN_NEXT,    HILSEN_START,   0)
    FUNC(hilse_take_idd, 0, HILSEN_MATCH,   HILSEN_IFCACF,  HILSEN_FOLLOW)
    OUT_LAST(HIL_PKT_CMD | HIL_CMD_RSC)
    EXPECT_LAST(HIL_PKT_CMD | HIL_CMD_RSC | HIL_ERR_INT,
           30000,       HILSEN_NEXT,    HILSEN_DSR, HILSEN_DSR)
    FUNC(hilse_take_rsc, 0, HILSEN_MATCH,   0,      HILSEN_FOLLOW)
    OUT_LAST(HIL_PKT_CMD | HIL_CMD_EXD)
    EXPECT_LAST(HIL_PKT_CMD | HIL_CMD_EXD | HIL_ERR_INT,
           30000,       HILSEN_NEXT,    HILSEN_DSR, HILSEN_DSR)
    FUNC(hilse_take_exd, 0, HILSEN_MATCH,   0,      HILSEN_FOLLOW)
    OUT_LAST(HIL_PKT_CMD | HIL_CMD_RNM)
    EXPECT_LAST(HIL_PKT_CMD | HIL_CMD_RNM | HIL_ERR_INT,
           30000,       HILSEN_NEXT,    HILSEN_DSR, HILSEN_DSR)
    FUNC(hilse_take_rnm, 0, HILSEN_MATCH,   0,      0)

    /* 40 HILSEN_MATCH */
    FUNC(hilse_match, 0,    HILSEN_NEXT,    HILSEN_NEXT,    /* TODO */ 0)

    /* 41 HILSEN_OPERATE */
    OUT(HIL_PKT_CMD | HIL_CMD_POL)
    EXPECT(HIL_PKT_CMD | HIL_CMD_POL | HIL_ERR_INT,
           20000,       HILSEN_NEXT,    HILSEN_DSR, HILSEN_NEXT)
    FUNC(hilse_operate, 0,  HILSEN_OPERATE, HILSEN_IFC, HILSEN_NEXT)

    /* 44 HILSEN_PROBE */
    OUT_LAST(HIL_PKT_CMD | HIL_CMD_EPT)
    IN(10000,       HILSEN_DISC,    HILSEN_DSR, HILSEN_NEXT)
    OUT_DISC(HIL_PKT_CMD | HIL_CMD_ELB)
    IN(10000,       HILSEN_DISC,    HILSEN_DSR, HILSEN_NEXT)
    OUT(HIL_PKT_CMD | HIL_CMD_ACF | 1)
    IN(10000,       HILSEN_DISC0,   HILSEN_DSR, HILSEN_NEXT)
    OUT_LAST(HIL_PKT_CMD | HIL_CMD_ELB)
    IN(10000,       HILSEN_OPERATE, HILSEN_DSR, HILSEN_DSR)

    /* 52 HILSEN_DSR */
    FUNC(hilse_set_ddi, -1, HILSEN_NEXT,    0,      0)
    OUT(HIL_PKT_CMD | HIL_CMD_DSR)
    IN(20000,       HILSEN_DHR, HILSEN_DHR, HILSEN_IFC)

    /* 55 HILSEN_REPOLL */
    OUT(HIL_PKT_CMD | HIL_CMD_RPL)
    EXPECT(HIL_PKT_CMD | HIL_CMD_RPL | HIL_ERR_INT,
           20000,       HILSEN_NEXT,    HILSEN_DSR, HILSEN_NEXT)
    FUNC(hilse_operate, 1,  HILSEN_OPERATE, HILSEN_IFC, HILSEN_PROBE)

    /* 58 HILSEN_IFCACF */
    OUT(HIL_PKT_CMD | HIL_CMD_IFC)
    EXPECT(HIL_PKT_CMD | HIL_CMD_IFC | HIL_ERR_INT,
           20000,       HILSEN_ACF2,    HILSEN_DHR2,    HILSEN_HEAL)

    /* 60 HILSEN_END */
};

static inline void hilse_setup_input(hil_mlc *mlc, const struct hilse_node *node)
{

    switch (node->act) {
    case HILSE_EXPECT_DISC:
        mlc->imatch = node->object.packet;
        mlc->imatch |= ((mlc->ddi + 2) << HIL_PKT_ADDR_SHIFT);
        break;
    case HILSE_EXPECT_LAST:
        mlc->imatch = node->object.packet;
        mlc->imatch |= ((mlc->ddi + 1) << HIL_PKT_ADDR_SHIFT);
        break;
    case HILSE_EXPECT:
        mlc->imatch = node->object.packet;
        break;
    case HILSE_IN:
        mlc->imatch = 0;
        break;
    default:
        BUG();
    }
    mlc->istarted = 1;
    mlc->intimeout = node->arg;
    do_gettimeofday(&(mlc->instart));
    mlc->icount = 15;
    memset(mlc->ipacket, 0, 16 * sizeof(hil_packet));
    BUG_ON(down_trylock(&mlc->isem));
}

#ifdef HIL_MLC_DEBUG
static int doze;
static int seidx; /* For debug */
#endif

static int hilse_donode(hil_mlc *mlc)
{
    const struct hilse_node *node;
    int nextidx = 0;
    int sched_long = 0;
    unsigned long flags;

#ifdef HIL_MLC_DEBUG
    if (mlc->seidx && mlc->seidx != seidx &&
        mlc->seidx != 41 && mlc->seidx != 42 && mlc->seidx != 43) {
        printk(KERN_DEBUG PREFIX "z%i \n {%i}", doze, mlc->seidx);
        doze = 0;
    }

    seidx = mlc->seidx;
#endif
    node = hil_mlc_se + mlc->seidx;

    switch (node->act) {
        int rc;
        hil_packet pack;

    case HILSE_FUNC:
        BUG_ON(node->object.func == NULL);
        rc = node->object.func(mlc, node->arg);
        nextidx = (rc > 0) ? node->ugly :
            ((rc < 0) ? node->bad : node->good);
        if (nextidx == HILSEN_FOLLOW)
            nextidx = rc;
        break;

    case HILSE_EXPECT_LAST:
    case HILSE_EXPECT_DISC:
    case HILSE_EXPECT:
    case HILSE_IN:
        /* Already set up from previous HILSE_OUT_* */
        write_lock_irqsave(&mlc->lock, flags);
        rc = mlc->in(mlc, node->arg);
        if (rc == 2)  {
            nextidx = HILSEN_DOZE;
            sched_long = 1;
            write_unlock_irqrestore(&mlc->lock, flags);
            break;
        }
        if (rc == 1)
            nextidx = node->ugly;
        else if (rc == 0)
            nextidx = node->good;
        else
            nextidx = node->bad;
        mlc->istarted = 0;
        write_unlock_irqrestore(&mlc->lock, flags);
        break;

    case HILSE_OUT_LAST:
        write_lock_irqsave(&mlc->lock, flags);
        pack = node->object.packet;
        pack |= ((mlc->ddi + 1) << HIL_PKT_ADDR_SHIFT);
        goto out;

    case HILSE_OUT_DISC:
        write_lock_irqsave(&mlc->lock, flags);
        pack = node->object.packet;
        pack |= ((mlc->ddi + 2) << HIL_PKT_ADDR_SHIFT);
        goto out;

    case HILSE_OUT:
        write_lock_irqsave(&mlc->lock, flags);
        pack = node->object.packet;
    out:
        if (mlc->istarted)
            goto out2;
        /* Prepare to receive input */
        if ((node + 1)->act & HILSE_IN)
            hilse_setup_input(mlc, node + 1);

    out2:
        write_unlock_irqrestore(&mlc->lock, flags);

        if (down_trylock(&mlc->osem)) {
            nextidx = HILSEN_DOZE;
            break;
        }
        up(&mlc->osem);

        write_lock_irqsave(&mlc->lock, flags);
        if (!mlc->ostarted) {
            mlc->ostarted = 1;
            mlc->opacket = pack;
            mlc->out(mlc);
            nextidx = HILSEN_DOZE;
            write_unlock_irqrestore(&mlc->lock, flags);
            break;
        }
        mlc->ostarted = 0;
        do_gettimeofday(&(mlc->instart));
        write_unlock_irqrestore(&mlc->lock, flags);
        nextidx = HILSEN_NEXT;
        break;

    case HILSE_CTS:
        write_lock_irqsave(&mlc->lock, flags);
        nextidx = mlc->cts(mlc) ? node->bad : node->good;
        write_unlock_irqrestore(&mlc->lock, flags);
        break;

    default:
        BUG();
    }

#ifdef HIL_MLC_DEBUG
    if (nextidx == HILSEN_DOZE)
        doze++;
#endif

    while (nextidx & HILSEN_SCHED) {
        struct timeval tv;

        if (!sched_long)
            goto sched;

        do_gettimeofday(&tv);
        tv.tv_usec += USEC_PER_SEC * (tv.tv_sec - mlc->instart.tv_sec);
        tv.tv_usec -= mlc->instart.tv_usec;
        if (tv.tv_usec >= mlc->intimeout) goto sched;
        tv.tv_usec = (mlc->intimeout - tv.tv_usec) * HZ / USEC_PER_SEC;
        if (!tv.tv_usec) goto sched;
        mod_timer(&hil_mlcs_kicker, jiffies + tv.tv_usec);
        break;
    sched:
        tasklet_schedule(&hil_mlcs_tasklet);
        break;
    }

    if (nextidx & HILSEN_DOWN)
        mlc->seidx += nextidx & HILSEN_MASK;
    else if (nextidx & HILSEN_UP)
        mlc->seidx -= nextidx & HILSEN_MASK;
    else
        mlc->seidx = nextidx & HILSEN_MASK;

    if (nextidx & HILSEN_BREAK)
        return 1;

    return 0;
}

/******************** tasklet context functions **************************/
static void hil_mlcs_process(unsigned long unused)
{
    struct list_head *tmp;

    read_lock(&hil_mlcs_lock);
    list_for_each(tmp, &hil_mlcs) {
        struct hil_mlc *mlc = list_entry(tmp, hil_mlc, list);
        while (hilse_donode(mlc) == 0) {
#ifdef HIL_MLC_DEBUG
            if (mlc->seidx != 41 &&
                mlc->seidx != 42 &&
                mlc->seidx != 43)
                printk(KERN_DEBUG PREFIX " + ");
#endif
        }
    }
    read_unlock(&hil_mlcs_lock);
}

/************************* Keepalive timer task *********************/

static void hil_mlcs_timer(unsigned long data)
{
    hil_mlcs_probe = 1;
    tasklet_schedule(&hil_mlcs_tasklet);
    /* Re-insert the periodic task. */
    if (!timer_pending(&hil_mlcs_kicker))
        mod_timer(&hil_mlcs_kicker, jiffies + HZ);
}

/******************** user/kernel context functions **********************/

static int hil_mlc_serio_write(struct serio *serio, unsigned char c)
{
    struct hil_mlc_serio_map *map;
    struct hil_mlc *mlc;
    struct serio_driver *drv;
    uint8_t *idx, *last;

    map = serio->port_data;
    BUG_ON(map == NULL);

    mlc = map->mlc;
    BUG_ON(mlc == NULL);

    mlc->serio_opacket[map->didx] |=
        ((hil_packet)c) << (8 * (3 - mlc->serio_oidx[map->didx]));

    if (mlc->serio_oidx[map->didx] >= 3) {
        /* for now only commands */
        if (!(mlc->serio_opacket[map->didx] & HIL_PKT_CMD))
            return -EIO;
        switch (mlc->serio_opacket[map->didx] & HIL_PKT_DATA_MASK) {
        case HIL_CMD_IDD:
            idx = mlc->di[map->didx].idd;
            goto emu;
        case HIL_CMD_RSC:
            idx = mlc->di[map->didx].rsc;
            goto emu;
        case HIL_CMD_EXD:
            idx = mlc->di[map->didx].exd;
            goto emu;
        case HIL_CMD_RNM:
            idx = mlc->di[map->didx].rnm;
            goto emu;
        default:
            break;
        }
        mlc->serio_oidx[map->didx] = 0;
        mlc->serio_opacket[map->didx] = 0;
    }

    mlc->serio_oidx[map->didx]++;
    return -EIO;
 emu:
    drv = serio->drv;
    BUG_ON(drv == NULL);

    last = idx + 15;
    while ((last != idx) && (*last == 0))
        last--;

    while (idx != last) {
        drv->interrupt(serio, 0, 0);
        drv->interrupt(serio, HIL_ERR_INT >> 16, 0);
        drv->interrupt(serio, 0, 0);
        drv->interrupt(serio, *idx, 0);
        idx++;
    }
    drv->interrupt(serio, 0, 0);
    drv->interrupt(serio, HIL_ERR_INT >> 16, 0);
    drv->interrupt(serio, HIL_PKT_CMD >> 8, 0);
    drv->interrupt(serio, *idx, 0);

    mlc->serio_oidx[map->didx] = 0;
    mlc->serio_opacket[map->didx] = 0;

    return 0;
}

static int hil_mlc_serio_open(struct serio *serio)
{
    struct hil_mlc_serio_map *map;
    struct hil_mlc *mlc;

    if (serio_get_drvdata(serio) != NULL)
        return -EBUSY;

    map = serio->port_data;
    BUG_ON(map == NULL);

    mlc = map->mlc;
    BUG_ON(mlc == NULL);

    return 0;
}

static void hil_mlc_serio_close(struct serio *serio)
{
    struct hil_mlc_serio_map *map;
    struct hil_mlc *mlc;

    map = serio->port_data;
    BUG_ON(map == NULL);

    mlc = map->mlc;
    BUG_ON(mlc == NULL);

    serio_set_drvdata(serio, NULL);
    serio->drv = NULL;
    /* TODO wake up interruptable */
}

static const struct serio_device_id hil_mlc_serio_id = {
    .type = SERIO_HIL_MLC,
    .proto = SERIO_HIL,
    .extra = SERIO_ANY,
    .id = SERIO_ANY,
};

int hil_mlc_register(hil_mlc *mlc)
{
    int i;
    unsigned long flags;

    BUG_ON(mlc == NULL);

    mlc->istarted = 0;
    mlc->ostarted = 0;

    rwlock_init(&mlc->lock);
    sema_init(&mlc->osem, 1);

    sema_init(&mlc->isem, 1);
    mlc->icount = -1;
    mlc->imatch = 0;

    mlc->opercnt = 0;

    sema_init(&(mlc->csem), 0);

    hil_mlc_clear_di_scratch(mlc);
    hil_mlc_clear_di_map(mlc, 0);
    for (i = 0; i < HIL_MLC_DEVMEM; i++) {
        struct serio *mlc_serio;
        hil_mlc_copy_di_scratch(mlc, i);
        mlc_serio = kzalloc(sizeof(*mlc_serio), GFP_KERNEL);
        mlc->serio[i] = mlc_serio;
        if (!mlc->serio[i]) {
            for (; i >= 0; i--)
                kfree(mlc->serio[i]);
            return -ENOMEM;
        }
        snprintf(mlc_serio->name, sizeof(mlc_serio->name)-1, "HIL_SERIO%d", i);
        snprintf(mlc_serio->phys, sizeof(mlc_serio->phys)-1, "HIL%d", i);
        mlc_serio->id           = hil_mlc_serio_id;
        mlc_serio->id.id        = i; /* HIL port no. */
        mlc_serio->write        = hil_mlc_serio_write;
        mlc_serio->open         = hil_mlc_serio_open;
        mlc_serio->close        = hil_mlc_serio_close;
        mlc_serio->port_data        = &(mlc->serio_map[i]);
        mlc->serio_map[i].mlc       = mlc;
        mlc->serio_map[i].didx      = i;
        mlc->serio_map[i].di_revmap = -1;
        mlc->serio_opacket[i]       = 0;
        mlc->serio_oidx[i]      = 0;
        serio_register_port(mlc_serio);
    }

    mlc->tasklet = &hil_mlcs_tasklet;

    write_lock_irqsave(&hil_mlcs_lock, flags);
    list_add_tail(&mlc->list, &hil_mlcs);
    mlc->seidx = HILSEN_START;
    write_unlock_irqrestore(&hil_mlcs_lock, flags);

    tasklet_schedule(&hil_mlcs_tasklet);
    return 0;
}

int hil_mlc_unregister(hil_mlc *mlc)
{
    struct list_head *tmp;
    unsigned long flags;
    int i;

    BUG_ON(mlc == NULL);

    write_lock_irqsave(&hil_mlcs_lock, flags);
    list_for_each(tmp, &hil_mlcs)
        if (list_entry(tmp, hil_mlc, list) == mlc)
            goto found;

    /* not found in list */
    write_unlock_irqrestore(&hil_mlcs_lock, flags);
    tasklet_schedule(&hil_mlcs_tasklet);
    return -ENODEV;

 found:
    list_del(tmp);
    write_unlock_irqrestore(&hil_mlcs_lock, flags);

    for (i = 0; i < HIL_MLC_DEVMEM; i++) {
        serio_unregister_port(mlc->serio[i]);
        mlc->serio[i] = NULL;
    }

    tasklet_schedule(&hil_mlcs_tasklet);
    return 0;
}

/**************************** Module interface *************************/

static int __init hil_mlc_init(void)
{
    setup_timer(&hil_mlcs_kicker, &hil_mlcs_timer, 0);
    mod_timer(&hil_mlcs_kicker, jiffies + HZ);

    tasklet_enable(&hil_mlcs_tasklet);

    return 0;
}

static void __exit hil_mlc_exit(void)
{
    del_timer_sync(&hil_mlcs_kicker);

    tasklet_disable(&hil_mlcs_tasklet);
    tasklet_kill(&hil_mlcs_tasklet);
}

module_init(hil_mlc_init);
module_exit(hil_mlc_exit);