/*
 * 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 <bri@calyx.com>");
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, hil_mlc_stop;

static void hil_mlcs_process(unsigned long unused);
static DECLARE_TASKLET_DISABLED_OLD(hil_mlcs_tasklet, hil_mlcs_process);


/* #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)
{
        time64_t now = ktime_get_seconds();

        if (mlc->lcv && (now - mlc->lcv_time) < 5)
                return -1;

        mlc->lcv_time = now;
        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 = usecs_to_jiffies(node->arg);
        mlc->instart = jiffies;
        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) {
                        /* Prepare to receive input */
                        if ((node + 1)->act & HILSE_IN)
                                hilse_setup_input(mlc, node + 1);
                }

                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;
                        rc = mlc->out(mlc);
                        nextidx = HILSEN_DOZE;
                        write_unlock_irqrestore(&mlc->lock, flags);
                        if (rc) {
                                hil_mlc_stop = 1;
                                return 1;
                        }
                        break;
                }
                mlc->ostarted = 0;
                mlc->instart = jiffies;
                write_unlock_irqrestore(&mlc->lock, flags);
                nextidx = HILSEN_NEXT;
                break;

        case HILSE_CTS:
                write_lock_irqsave(&mlc->lock, flags);
                rc = mlc->cts(mlc);
                nextidx = rc ? node->bad : node->good;
                write_unlock_irqrestore(&mlc->lock, flags);
                if (rc) {
                        hil_mlc_stop = 1;
                        return 1;
                }
                break;

        default:
                BUG();
        }

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

        while (nextidx & HILSEN_SCHED) {
                unsigned long now = jiffies;

                if (!sched_long)
                        goto sched;

                if (time_after(now, mlc->instart + mlc->intimeout))
                         goto sched;
                mod_timer(&hil_mlcs_kicker, mlc->instart + mlc->intimeout);
                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(struct timer_list *unused)
{
        if (hil_mlc_stop) {
                /* could not send packet - stop immediately. */
                pr_warn(PREFIX "HIL seems stuck - Disabling HIL MLC.\n");
                return;
        }

        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)
{
        timer_setup(&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_kill(&hil_mlcs_tasklet);
}

module_init(hil_mlc_init);
module_exit(hil_mlc_exit);