hp_sdc.c

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/*
 * HP i8042-based System Device Controller 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:
 * System Device Controller Microprocessor Firmware Theory of Operation
 *      for Part Number 1820-4784 Revision B.  Dwg No. A-1820-4784-2
 * Helge Deller's original hilkbd.c port for PA-RISC.
 *
 *
 * Driver theory of operation:
 *
 * hp_sdc_put does all writing to the SDC.  ISR can run on a different
 * CPU than hp_sdc_put, but only one CPU runs hp_sdc_put at a time
 * (it cannot really benefit from SMP anyway.)  A tasket fit this perfectly.
 *
 * All data coming back from the SDC is sent via interrupt and can be read
 * fully in the ISR, so there are no latency/throughput problems there.
 * The problem is with output, due to the slow clock speed of the SDC
 * compared to the CPU.  This should not be too horrible most of the time,
 * but if used with HIL devices that support the multibyte transfer command,
 * keeping outbound throughput flowing at the 6500KBps that the HIL is
 * capable of is more than can be done at HZ=100.
 *
 * Busy polling for IBF clear wastes CPU cycles and bus cycles.  hp_sdc.ibf
 * is set to 0 when the IBF flag in the status register has cleared.  ISR
 * may do this, and may also access the parts of queued transactions related
 * to reading data back from the SDC, but otherwise will not touch the
 * hp_sdc state. Whenever a register is written hp_sdc.ibf is set to 1.
 *
 * The i8042 write index and the values in the 4-byte input buffer
 * starting at 0x70 are kept track of in hp_sdc.wi, and .r7[], respectively,
 * to minimize the amount of IO needed to the SDC.  However these values
 * do not need to be locked since they are only ever accessed by hp_sdc_put.
 *
 * A timer task schedules the tasklet once per second just to make
 * sure it doesn't freeze up and to allow for bad reads to time out.
 */

#include <linux/hp_sdc.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/ioport.h>
#include <linux/time.h>
#include <linux/semaphore.h>
#include <linux/slab.h>
#include <linux/hil.h>
#include <asm/io.h>

/* Machine-specific abstraction */

#if defined(__hppa__)
# include <asm/parisc-device.h>
# define sdc_readb(p)       gsc_readb(p)
# define sdc_writeb(v,p)    gsc_writeb((v),(p))
#elif defined(__mc68000__)
# include <asm/uaccess.h>
# define sdc_readb(p)       in_8(p)
# define sdc_writeb(v,p)    out_8((p),(v))
#else
# error "HIL is not supported on this platform"
#endif

#define PREFIX "HP SDC: "

MODULE_AUTHOR("Brian S. Julin <[email protected]>");
MODULE_DESCRIPTION("HP i8042-based SDC Driver");
MODULE_LICENSE("Dual BSD/GPL");

EXPORT_SYMBOL(hp_sdc_request_timer_irq);
EXPORT_SYMBOL(hp_sdc_request_hil_irq);
EXPORT_SYMBOL(hp_sdc_request_cooked_irq);

EXPORT_SYMBOL(hp_sdc_release_timer_irq);
EXPORT_SYMBOL(hp_sdc_release_hil_irq);
EXPORT_SYMBOL(hp_sdc_release_cooked_irq);

EXPORT_SYMBOL(__hp_sdc_enqueue_transaction);
EXPORT_SYMBOL(hp_sdc_enqueue_transaction);
EXPORT_SYMBOL(hp_sdc_dequeue_transaction);

static bool hp_sdc_disabled;
module_param_named(no_hpsdc, hp_sdc_disabled, bool, 0);
MODULE_PARM_DESC(no_hpsdc, "Do not enable HP SDC driver.");

static hp_i8042_sdc hp_sdc; /* All driver state is kept in here. */

/*************** primitives for use in any context *********************/
static inline uint8_t hp_sdc_status_in8(void)
{
    uint8_t status;
    unsigned long flags;

    write_lock_irqsave(&hp_sdc.ibf_lock, flags);
    status = sdc_readb(hp_sdc.status_io);
    if (!(status & HP_SDC_STATUS_IBF))
        hp_sdc.ibf = 0;
    write_unlock_irqrestore(&hp_sdc.ibf_lock, flags);

    return status;
}

static inline uint8_t hp_sdc_data_in8(void)
{
    return sdc_readb(hp_sdc.data_io);
}

static inline void hp_sdc_status_out8(uint8_t val)
{
    unsigned long flags;

    write_lock_irqsave(&hp_sdc.ibf_lock, flags);
    hp_sdc.ibf = 1;
    if ((val & 0xf0) == 0xe0)
        hp_sdc.wi = 0xff;
    sdc_writeb(val, hp_sdc.status_io);
    write_unlock_irqrestore(&hp_sdc.ibf_lock, flags);
}

static inline void hp_sdc_data_out8(uint8_t val)
{
    unsigned long flags;

    write_lock_irqsave(&hp_sdc.ibf_lock, flags);
    hp_sdc.ibf = 1;
    sdc_writeb(val, hp_sdc.data_io);
    write_unlock_irqrestore(&hp_sdc.ibf_lock, flags);
}

/*  Care must be taken to only invoke hp_sdc_spin_ibf when
 *  absolutely needed, or in rarely invoked subroutines.
 *  Not only does it waste CPU cycles, it also wastes bus cycles.
 */
static inline void hp_sdc_spin_ibf(void)
{
    unsigned long flags;
    rwlock_t *lock;

    lock = &hp_sdc.ibf_lock;

    read_lock_irqsave(lock, flags);
    if (!hp_sdc.ibf) {
        read_unlock_irqrestore(lock, flags);
        return;
    }
    read_unlock(lock);
    write_lock(lock);
    while (sdc_readb(hp_sdc.status_io) & HP_SDC_STATUS_IBF)
        { }
    hp_sdc.ibf = 0;
    write_unlock_irqrestore(lock, flags);
}


/************************ Interrupt context functions ************************/
static void hp_sdc_take(int irq, void *dev_id, uint8_t status, uint8_t data)
{
    hp_sdc_transaction *curr;

    read_lock(&hp_sdc.rtq_lock);
    if (hp_sdc.rcurr < 0) {
        read_unlock(&hp_sdc.rtq_lock);
        return;
    }
    curr = hp_sdc.tq[hp_sdc.rcurr];
    read_unlock(&hp_sdc.rtq_lock);

    curr->seq[curr->idx++] = status;
    curr->seq[curr->idx++] = data;
    hp_sdc.rqty -= 2;
    do_gettimeofday(&hp_sdc.rtv);

    if (hp_sdc.rqty <= 0) {
        /* All data has been gathered. */
        if (curr->seq[curr->actidx] & HP_SDC_ACT_SEMAPHORE)
            if (curr->act.semaphore)
                up(curr->act.semaphore);

        if (curr->seq[curr->actidx] & HP_SDC_ACT_CALLBACK)
            if (curr->act.irqhook)
                curr->act.irqhook(irq, dev_id, status, data);

        curr->actidx = curr->idx;
        curr->idx++;
        /* Return control of this transaction */
        write_lock(&hp_sdc.rtq_lock);
        hp_sdc.rcurr = -1;
        hp_sdc.rqty = 0;
        write_unlock(&hp_sdc.rtq_lock);
        tasklet_schedule(&hp_sdc.task);
    }
}

static irqreturn_t hp_sdc_isr(int irq, void *dev_id)
{
    uint8_t status, data;

    status = hp_sdc_status_in8();
    /* Read data unconditionally to advance i8042. */
    data =   hp_sdc_data_in8();

    /* For now we are ignoring these until we get the SDC to behave. */
    if (((status & 0xf1) == 0x51) && data == 0x82)
        return IRQ_HANDLED;

    switch (status & HP_SDC_STATUS_IRQMASK) {
    case 0: /* This case is not documented. */
        break;

    case HP_SDC_STATUS_USERTIMER:
    case HP_SDC_STATUS_PERIODIC:
    case HP_SDC_STATUS_TIMER:
        read_lock(&hp_sdc.hook_lock);
        if (hp_sdc.timer != NULL)
            hp_sdc.timer(irq, dev_id, status, data);
        read_unlock(&hp_sdc.hook_lock);
        break;

    case HP_SDC_STATUS_REG:
        hp_sdc_take(irq, dev_id, status, data);
        break;

    case HP_SDC_STATUS_HILCMD:
    case HP_SDC_STATUS_HILDATA:
        read_lock(&hp_sdc.hook_lock);
        if (hp_sdc.hil != NULL)
            hp_sdc.hil(irq, dev_id, status, data);
        read_unlock(&hp_sdc.hook_lock);
        break;

    case HP_SDC_STATUS_PUP:
        read_lock(&hp_sdc.hook_lock);
        if (hp_sdc.pup != NULL)
            hp_sdc.pup(irq, dev_id, status, data);
        else
            printk(KERN_INFO PREFIX "HP SDC reports successful PUP.\n");
        read_unlock(&hp_sdc.hook_lock);
        break;

    default:
        read_lock(&hp_sdc.hook_lock);
        if (hp_sdc.cooked != NULL)
            hp_sdc.cooked(irq, dev_id, status, data);
        read_unlock(&hp_sdc.hook_lock);
        break;
    }

    return IRQ_HANDLED;
}


static irqreturn_t hp_sdc_nmisr(int irq, void *dev_id)
{
    int status;

    status = hp_sdc_status_in8();
    printk(KERN_WARNING PREFIX "NMI !\n");

#if 0
    if (status & HP_SDC_NMISTATUS_FHS) {
        read_lock(&hp_sdc.hook_lock);
        if (hp_sdc.timer != NULL)
            hp_sdc.timer(irq, dev_id, status, 0);
        read_unlock(&hp_sdc.hook_lock);
    } else {
        /* TODO: pass this on to the HIL handler, or do SAK here? */
        printk(KERN_WARNING PREFIX "HIL NMI\n");
    }
#endif

    return IRQ_HANDLED;
}


/***************** Kernel (tasklet) context functions ****************/

unsigned long hp_sdc_put(void);

static void hp_sdc_tasklet(unsigned long foo)
{
    write_lock_irq(&hp_sdc.rtq_lock);

    if (hp_sdc.rcurr >= 0) {
        struct timeval tv;

        do_gettimeofday(&tv);
        if (tv.tv_sec > hp_sdc.rtv.tv_sec)
            tv.tv_usec += USEC_PER_SEC;

        if (tv.tv_usec - hp_sdc.rtv.tv_usec > HP_SDC_MAX_REG_DELAY) {
            hp_sdc_transaction *curr;
            uint8_t tmp;

            curr = hp_sdc.tq[hp_sdc.rcurr];
            /* If this turns out to be a normal failure mode
             * we'll need to figure out a way to communicate
             * it back to the application. and be less verbose.
             */
            printk(KERN_WARNING PREFIX "read timeout (%ius)!\n",
                   (int)(tv.tv_usec - hp_sdc.rtv.tv_usec));
            curr->idx += hp_sdc.rqty;
            hp_sdc.rqty = 0;
            tmp = curr->seq[curr->actidx];
            curr->seq[curr->actidx] |= HP_SDC_ACT_DEAD;
            if (tmp & HP_SDC_ACT_SEMAPHORE)
                if (curr->act.semaphore)
                    up(curr->act.semaphore);

            if (tmp & HP_SDC_ACT_CALLBACK) {
                /* Note this means that irqhooks may be called
                 * in tasklet/bh context.
                 */
                if (curr->act.irqhook)
                    curr->act.irqhook(0, NULL, 0, 0);
            }

            curr->actidx = curr->idx;
            curr->idx++;
            hp_sdc.rcurr = -1;
        }
    }
    write_unlock_irq(&hp_sdc.rtq_lock);
    hp_sdc_put();
}

unsigned long hp_sdc_put(void)
{
    hp_sdc_transaction *curr;
    uint8_t act;
    int idx, curridx;

    int limit = 0;

    write_lock(&hp_sdc.lock);

    /* If i8042 buffers are full, we cannot do anything that
       requires output, so we skip to the administrativa. */
    if (hp_sdc.ibf) {
        hp_sdc_status_in8();
        if (hp_sdc.ibf)
            goto finish;
    }

 anew:
    /* See if we are in the middle of a sequence. */
    if (hp_sdc.wcurr < 0)
        hp_sdc.wcurr = 0;
    read_lock_irq(&hp_sdc.rtq_lock);
    if (hp_sdc.rcurr == hp_sdc.wcurr)
        hp_sdc.wcurr++;
    read_unlock_irq(&hp_sdc.rtq_lock);
    if (hp_sdc.wcurr >= HP_SDC_QUEUE_LEN)
        hp_sdc.wcurr = 0;
    curridx = hp_sdc.wcurr;

    if (hp_sdc.tq[curridx] != NULL)
        goto start;

    while (++curridx != hp_sdc.wcurr) {
        if (curridx >= HP_SDC_QUEUE_LEN) {
            curridx = -1; /* Wrap to top */
            continue;
        }
        read_lock_irq(&hp_sdc.rtq_lock);
        if (hp_sdc.rcurr == curridx) {
            read_unlock_irq(&hp_sdc.rtq_lock);
            continue;
        }
        read_unlock_irq(&hp_sdc.rtq_lock);
        if (hp_sdc.tq[curridx] != NULL)
            break; /* Found one. */
    }
    if (curridx == hp_sdc.wcurr) { /* There's nothing queued to do. */
        curridx = -1;
    }
    hp_sdc.wcurr = curridx;

 start:

    /* Check to see if the interrupt mask needs to be set. */
    if (hp_sdc.set_im) {
        hp_sdc_status_out8(hp_sdc.im | HP_SDC_CMD_SET_IM);
        hp_sdc.set_im = 0;
        goto finish;
    }

    if (hp_sdc.wcurr == -1)
        goto done;

    curr = hp_sdc.tq[curridx];
    idx = curr->actidx;

    if (curr->actidx >= curr->endidx) {
        hp_sdc.tq[curridx] = NULL;
        /* Interleave outbound data between the transactions. */
        hp_sdc.wcurr++;
        if (hp_sdc.wcurr >= HP_SDC_QUEUE_LEN)
            hp_sdc.wcurr = 0;
        goto finish;
    }

    act = curr->seq[idx];
    idx++;

    if (curr->idx >= curr->endidx) {
        if (act & HP_SDC_ACT_DEALLOC)
            kfree(curr);
        hp_sdc.tq[curridx] = NULL;
        /* Interleave outbound data between the transactions. */
        hp_sdc.wcurr++;
        if (hp_sdc.wcurr >= HP_SDC_QUEUE_LEN)
            hp_sdc.wcurr = 0;
        goto finish;
    }

    while (act & HP_SDC_ACT_PRECMD) {
        if (curr->idx != idx) {
            idx++;
            act &= ~HP_SDC_ACT_PRECMD;
            break;
        }
        hp_sdc_status_out8(curr->seq[idx]);
        curr->idx++;
        /* act finished? */
        if ((act & HP_SDC_ACT_DURING) == HP_SDC_ACT_PRECMD)
            goto actdone;
        /* skip quantity field if data-out sequence follows. */
        if (act & HP_SDC_ACT_DATAOUT)
            curr->idx++;
        goto finish;
    }
    if (act & HP_SDC_ACT_DATAOUT) {
        int qty;

        qty = curr->seq[idx];
        idx++;
        if (curr->idx - idx < qty) {
            hp_sdc_data_out8(curr->seq[curr->idx]);
            curr->idx++;
            /* act finished? */
            if (curr->idx - idx >= qty &&
                (act & HP_SDC_ACT_DURING) == HP_SDC_ACT_DATAOUT)
                goto actdone;
            goto finish;
        }
        idx += qty;
        act &= ~HP_SDC_ACT_DATAOUT;
    } else
        while (act & HP_SDC_ACT_DATAREG) {
        int mask;
        uint8_t w7[4];

        mask = curr->seq[idx];
        if (idx != curr->idx) {
            idx++;
            idx += !!(mask & 1);
            idx += !!(mask & 2);
            idx += !!(mask & 4);
            idx += !!(mask & 8);
            act &= ~HP_SDC_ACT_DATAREG;
            break;
        }

        w7[0] = (mask & 1) ? curr->seq[++idx] : hp_sdc.r7[0];
        w7[1] = (mask & 2) ? curr->seq[++idx] : hp_sdc.r7[1];
        w7[2] = (mask & 4) ? curr->seq[++idx] : hp_sdc.r7[2];
        w7[3] = (mask & 8) ? curr->seq[++idx] : hp_sdc.r7[3];

        if (hp_sdc.wi > 0x73 || hp_sdc.wi < 0x70 ||
            w7[hp_sdc.wi - 0x70] == hp_sdc.r7[hp_sdc.wi - 0x70]) {
            int i = 0;

            /* Need to point the write index register */
            while (i < 4 && w7[i] == hp_sdc.r7[i])
                i++;

            if (i < 4) {
                hp_sdc_status_out8(HP_SDC_CMD_SET_D0 + i);
                hp_sdc.wi = 0x70 + i;
                goto finish;
            }

            idx++;
            if ((act & HP_SDC_ACT_DURING) == HP_SDC_ACT_DATAREG)
                goto actdone;

            curr->idx = idx;
            act &= ~HP_SDC_ACT_DATAREG;
            break;
        }

        hp_sdc_data_out8(w7[hp_sdc.wi - 0x70]);
        hp_sdc.r7[hp_sdc.wi - 0x70] = w7[hp_sdc.wi - 0x70];
        hp_sdc.wi++; /* write index register autoincrements */
        {
            int i = 0;

            while ((i < 4) && w7[i] == hp_sdc.r7[i])
                i++;
            if (i >= 4) {
                curr->idx = idx + 1;
                if ((act & HP_SDC_ACT_DURING) ==
                    HP_SDC_ACT_DATAREG)
                    goto actdone;
            }
        }
        goto finish;
    }
    /* We don't go any further in the command if there is a pending read,
       because we don't want interleaved results. */
    read_lock_irq(&hp_sdc.rtq_lock);
    if (hp_sdc.rcurr >= 0) {
        read_unlock_irq(&hp_sdc.rtq_lock);
        goto finish;
    }
    read_unlock_irq(&hp_sdc.rtq_lock);


    if (act & HP_SDC_ACT_POSTCMD) {
        uint8_t postcmd;

        /* curr->idx should == idx at this point. */
        postcmd = curr->seq[idx];
        curr->idx++;
        if (act & HP_SDC_ACT_DATAIN) {

            /* Start a new read */
            hp_sdc.rqty = curr->seq[curr->idx];
            do_gettimeofday(&hp_sdc.rtv);
            curr->idx++;
            /* Still need to lock here in case of spurious irq. */
            write_lock_irq(&hp_sdc.rtq_lock);
            hp_sdc.rcurr = curridx;
            write_unlock_irq(&hp_sdc.rtq_lock);
            hp_sdc_status_out8(postcmd);
            goto finish;
        }
        hp_sdc_status_out8(postcmd);
        goto actdone;
    }

 actdone:
    if (act & HP_SDC_ACT_SEMAPHORE)
        up(curr->act.semaphore);
    else if (act & HP_SDC_ACT_CALLBACK)
        curr->act.irqhook(0,NULL,0,0);

    if (curr->idx >= curr->endidx) { /* This transaction is over. */
        if (act & HP_SDC_ACT_DEALLOC)
            kfree(curr);
        hp_sdc.tq[curridx] = NULL;
    } else {
        curr->actidx = idx + 1;
        curr->idx = idx + 2;
    }
    /* Interleave outbound data between the transactions. */
    hp_sdc.wcurr++;
    if (hp_sdc.wcurr >= HP_SDC_QUEUE_LEN)
        hp_sdc.wcurr = 0;

 finish:
    /* If by some quirk IBF has cleared and our ISR has run to
       see that that has happened, do it all again. */
    if (!hp_sdc.ibf && limit++ < 20)
        goto anew;

 done:
    if (hp_sdc.wcurr >= 0)
        tasklet_schedule(&hp_sdc.task);
    write_unlock(&hp_sdc.lock);

    return 0;
}

/******* Functions called in either user or kernel context ****/
int __hp_sdc_enqueue_transaction(hp_sdc_transaction *this)
{
    int i;

    if (this == NULL) {
        BUG();
        return -EINVAL;
    }

    /* Can't have same transaction on queue twice */
    for (i = 0; i < HP_SDC_QUEUE_LEN; i++)
        if (hp_sdc.tq[i] == this)
            goto fail;

    this->actidx = 0;
    this->idx = 1;

    /* Search for empty slot */
    for (i = 0; i < HP_SDC_QUEUE_LEN; i++)
        if (hp_sdc.tq[i] == NULL) {
            hp_sdc.tq[i] = this;
            tasklet_schedule(&hp_sdc.task);
            return 0;
        }

    printk(KERN_WARNING PREFIX "No free slot to add transaction.\n");
    return -EBUSY;

 fail:
    printk(KERN_WARNING PREFIX "Transaction add failed: transaction already queued?\n");
    return -EINVAL;
}

int hp_sdc_enqueue_transaction(hp_sdc_transaction *this) {
    unsigned long flags;
    int ret;

    write_lock_irqsave(&hp_sdc.lock, flags);
    ret = __hp_sdc_enqueue_transaction(this);
    write_unlock_irqrestore(&hp_sdc.lock,flags);

    return ret;
}

int hp_sdc_dequeue_transaction(hp_sdc_transaction *this)
{
    unsigned long flags;
    int i;

    write_lock_irqsave(&hp_sdc.lock, flags);

    /* TODO: don't remove it if it's not done. */

    for (i = 0; i < HP_SDC_QUEUE_LEN; i++)
        if (hp_sdc.tq[i] == this)
            hp_sdc.tq[i] = NULL;

    write_unlock_irqrestore(&hp_sdc.lock, flags);
    return 0;
}



/********************** User context functions **************************/
int hp_sdc_request_timer_irq(hp_sdc_irqhook *callback)
{
    if (callback == NULL || hp_sdc.dev == NULL)
        return -EINVAL;

    write_lock_irq(&hp_sdc.hook_lock);
    if (hp_sdc.timer != NULL) {
        write_unlock_irq(&hp_sdc.hook_lock);
        return -EBUSY;
    }

    hp_sdc.timer = callback;
    /* Enable interrupts from the timers */
    hp_sdc.im &= ~HP_SDC_IM_FH;
        hp_sdc.im &= ~HP_SDC_IM_PT;
    hp_sdc.im &= ~HP_SDC_IM_TIMERS;
    hp_sdc.set_im = 1;
    write_unlock_irq(&hp_sdc.hook_lock);

    tasklet_schedule(&hp_sdc.task);

    return 0;
}

int hp_sdc_request_hil_irq(hp_sdc_irqhook *callback)
{
    if (callback == NULL || hp_sdc.dev == NULL)
        return -EINVAL;

    write_lock_irq(&hp_sdc.hook_lock);
    if (hp_sdc.hil != NULL) {
        write_unlock_irq(&hp_sdc.hook_lock);
        return -EBUSY;
    }

    hp_sdc.hil = callback;
    hp_sdc.im &= ~(HP_SDC_IM_HIL | HP_SDC_IM_RESET);
    hp_sdc.set_im = 1;
    write_unlock_irq(&hp_sdc.hook_lock);

    tasklet_schedule(&hp_sdc.task);

    return 0;
}

int hp_sdc_request_cooked_irq(hp_sdc_irqhook *callback)
{
    if (callback == NULL || hp_sdc.dev == NULL)
        return -EINVAL;

    write_lock_irq(&hp_sdc.hook_lock);
    if (hp_sdc.cooked != NULL) {
        write_unlock_irq(&hp_sdc.hook_lock);
        return -EBUSY;
    }

    /* Enable interrupts from the HIL MLC */
    hp_sdc.cooked = callback;
    hp_sdc.im &= ~(HP_SDC_IM_HIL | HP_SDC_IM_RESET);
    hp_sdc.set_im = 1;
    write_unlock_irq(&hp_sdc.hook_lock);

    tasklet_schedule(&hp_sdc.task);

    return 0;
}

int hp_sdc_release_timer_irq(hp_sdc_irqhook *callback)
{
    write_lock_irq(&hp_sdc.hook_lock);
    if ((callback != hp_sdc.timer) ||
        (hp_sdc.timer == NULL)) {
        write_unlock_irq(&hp_sdc.hook_lock);
        return -EINVAL;
    }

    /* Disable interrupts from the timers */
    hp_sdc.timer = NULL;
    hp_sdc.im |= HP_SDC_IM_TIMERS;
    hp_sdc.im |= HP_SDC_IM_FH;
    hp_sdc.im |= HP_SDC_IM_PT;
    hp_sdc.set_im = 1;
    write_unlock_irq(&hp_sdc.hook_lock);
    tasklet_schedule(&hp_sdc.task);

    return 0;
}

int hp_sdc_release_hil_irq(hp_sdc_irqhook *callback)
{
    write_lock_irq(&hp_sdc.hook_lock);
    if ((callback != hp_sdc.hil) ||
        (hp_sdc.hil == NULL)) {
        write_unlock_irq(&hp_sdc.hook_lock);
        return -EINVAL;
    }

    hp_sdc.hil = NULL;
    /* Disable interrupts from HIL only if there is no cooked driver. */
    if(hp_sdc.cooked == NULL) {
        hp_sdc.im |= (HP_SDC_IM_HIL | HP_SDC_IM_RESET);
        hp_sdc.set_im = 1;
    }
    write_unlock_irq(&hp_sdc.hook_lock);
    tasklet_schedule(&hp_sdc.task);

    return 0;
}

int hp_sdc_release_cooked_irq(hp_sdc_irqhook *callback)
{
    write_lock_irq(&hp_sdc.hook_lock);
    if ((callback != hp_sdc.cooked) ||
        (hp_sdc.cooked == NULL)) {
        write_unlock_irq(&hp_sdc.hook_lock);
        return -EINVAL;
    }

    hp_sdc.cooked = NULL;
    /* Disable interrupts from HIL only if there is no raw HIL driver. */
    if(hp_sdc.hil == NULL) {
        hp_sdc.im |= (HP_SDC_IM_HIL | HP_SDC_IM_RESET);
        hp_sdc.set_im = 1;
    }
    write_unlock_irq(&hp_sdc.hook_lock);
    tasklet_schedule(&hp_sdc.task);

    return 0;
}

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

static void hp_sdc_kicker(unsigned long data)
{
    tasklet_schedule(&hp_sdc.task);
    /* Re-insert the periodic task. */
    mod_timer(&hp_sdc.kicker, jiffies + HZ);
}

/************************** Module Initialization ***************************/

#if defined(__hppa__)

static const struct parisc_device_id hp_sdc_tbl[] = {
    {
        .hw_type =  HPHW_FIO,
        .hversion_rev = HVERSION_REV_ANY_ID,
        .hversion = HVERSION_ANY_ID,
        .sversion = 0x73,
     },
    { 0, }
};

MODULE_DEVICE_TABLE(parisc, hp_sdc_tbl);

static int __init hp_sdc_init_hppa(struct parisc_device *d);
static struct delayed_work moduleloader_work;

static struct parisc_driver hp_sdc_driver = {
    .name =     "hp_sdc",
    .id_table = hp_sdc_tbl,
    .probe =    hp_sdc_init_hppa,
};

#endif /* __hppa__ */

static int __init hp_sdc_init(void)
{
    char *errstr;
    hp_sdc_transaction t_sync;
    uint8_t ts_sync[6];
    struct semaphore s_sync;

    rwlock_init(&hp_sdc.lock);
    rwlock_init(&hp_sdc.ibf_lock);
    rwlock_init(&hp_sdc.rtq_lock);
    rwlock_init(&hp_sdc.hook_lock);

    hp_sdc.timer        = NULL;
    hp_sdc.hil      = NULL;
    hp_sdc.pup      = NULL;
    hp_sdc.cooked       = NULL;
    hp_sdc.im       = HP_SDC_IM_MASK;  /* Mask maskable irqs */
    hp_sdc.set_im       = 1;
    hp_sdc.wi       = 0xff;
    hp_sdc.r7[0]        = 0xff;
    hp_sdc.r7[1]        = 0xff;
    hp_sdc.r7[2]        = 0xff;
    hp_sdc.r7[3]        = 0xff;
    hp_sdc.ibf      = 1;

    memset(&hp_sdc.tq, 0, sizeof(hp_sdc.tq));

    hp_sdc.wcurr        = -1;
        hp_sdc.rcurr        = -1;
    hp_sdc.rqty     = 0;

    hp_sdc.dev_err = -ENODEV;

    errstr = "IO not found for";
    if (!hp_sdc.base_io)
        goto err0;

    errstr = "IRQ not found for";
    if (!hp_sdc.irq)
        goto err0;

    hp_sdc.dev_err = -EBUSY;

#if defined(__hppa__)
    errstr = "IO not available for";
        if (request_region(hp_sdc.data_io, 2, hp_sdc_driver.name))
        goto err0;
#endif

    errstr = "IRQ not available for";
    if (request_irq(hp_sdc.irq, &hp_sdc_isr, IRQF_SHARED,
            "HP SDC", &hp_sdc))
        goto err1;

    errstr = "NMI not available for";
    if (request_irq(hp_sdc.nmi, &hp_sdc_nmisr, IRQF_SHARED,
            "HP SDC NMI", &hp_sdc))
        goto err2;

    printk(KERN_INFO PREFIX "HP SDC at 0x%p, IRQ %d (NMI IRQ %d)\n",
           (void *)hp_sdc.base_io, hp_sdc.irq, hp_sdc.nmi);

    hp_sdc_status_in8();
    hp_sdc_data_in8();

    tasklet_init(&hp_sdc.task, hp_sdc_tasklet, 0);

    /* Sync the output buffer registers, thus scheduling hp_sdc_tasklet. */
    t_sync.actidx   = 0;
    t_sync.idx  = 1;
    t_sync.endidx   = 6;
    t_sync.seq  = ts_sync;
    ts_sync[0]  = HP_SDC_ACT_DATAREG | HP_SDC_ACT_SEMAPHORE;
    ts_sync[1]  = 0x0f;
    ts_sync[2] = ts_sync[3] = ts_sync[4] = ts_sync[5] = 0;
    t_sync.act.semaphore = &s_sync;
    sema_init(&s_sync, 0);
    hp_sdc_enqueue_transaction(&t_sync);
    down(&s_sync); /* Wait for t_sync to complete */

    /* Create the keepalive task */
    init_timer(&hp_sdc.kicker);
    hp_sdc.kicker.expires = jiffies + HZ;
    hp_sdc.kicker.function = &hp_sdc_kicker;
    add_timer(&hp_sdc.kicker);

    hp_sdc.dev_err = 0;
    return 0;
 err2:
    free_irq(hp_sdc.irq, &hp_sdc);
 err1:
    release_region(hp_sdc.data_io, 2);
 err0:
    printk(KERN_WARNING PREFIX ": %s SDC IO=0x%p IRQ=0x%x NMI=0x%x\n",
        errstr, (void *)hp_sdc.base_io, hp_sdc.irq, hp_sdc.nmi);
    hp_sdc.dev = NULL;

    return hp_sdc.dev_err;
}

#if defined(__hppa__)

static void request_module_delayed(struct work_struct *work)
{
    request_module("hp_sdc_mlc");
}

static int __init hp_sdc_init_hppa(struct parisc_device *d)
{
    int ret;

    if (!d)
        return 1;
    if (hp_sdc.dev != NULL)
        return 1;   /* We only expect one SDC */

    hp_sdc.dev      = d;
    hp_sdc.irq      = d->irq;
    hp_sdc.nmi      = d->aux_irq;
    hp_sdc.base_io      = d->hpa.start;
    hp_sdc.data_io      = d->hpa.start + 0x800;
    hp_sdc.status_io    = d->hpa.start + 0x801;

    INIT_DELAYED_WORK(&moduleloader_work, request_module_delayed);

    ret = hp_sdc_init();
    /* after successful initialization give SDC some time to settle
     * and then load the hp_sdc_mlc upper layer driver */
    if (!ret)
        schedule_delayed_work(&moduleloader_work,
            msecs_to_jiffies(2000));

    return ret;
}

#endif /* __hppa__ */

static void hp_sdc_exit(void)
{
    /* do nothing if we don't have a SDC */
    if (!hp_sdc.dev)
        return;

    write_lock_irq(&hp_sdc.lock);

    /* Turn off all maskable "sub-function" irq's. */
    hp_sdc_spin_ibf();
    sdc_writeb(HP_SDC_CMD_SET_IM | HP_SDC_IM_MASK, hp_sdc.status_io);

    /* Wait until we know this has been processed by the i8042 */
    hp_sdc_spin_ibf();

    free_irq(hp_sdc.nmi, &hp_sdc);
    free_irq(hp_sdc.irq, &hp_sdc);
    write_unlock_irq(&hp_sdc.lock);

    del_timer(&hp_sdc.kicker);

    tasklet_kill(&hp_sdc.task);

#if defined(__hppa__)
    cancel_delayed_work_sync(&moduleloader_work);
    if (unregister_parisc_driver(&hp_sdc_driver))
        printk(KERN_WARNING PREFIX "Error unregistering HP SDC");
#endif
}

static int __init hp_sdc_register(void)
{
    hp_sdc_transaction tq_init;
    uint8_t tq_init_seq[5];
    struct semaphore tq_init_sem;
#if defined(__mc68000__)
    mm_segment_t fs;
    unsigned char i;
#endif

    if (hp_sdc_disabled) {
        printk(KERN_WARNING PREFIX "HP SDC driver disabled by no_hpsdc=1.\n");
        return -ENODEV;
    }

    hp_sdc.dev = NULL;
    hp_sdc.dev_err = 0;
#if defined(__hppa__)
    if (register_parisc_driver(&hp_sdc_driver)) {
        printk(KERN_WARNING PREFIX "Error registering SDC with system bus tree.\n");
        return -ENODEV;
    }
#elif defined(__mc68000__)
    if (!MACH_IS_HP300)
        return -ENODEV;

    hp_sdc.irq   = 1;
    hp_sdc.nmi   = 7;
    hp_sdc.base_io   = (unsigned long) 0xf0428000;
    hp_sdc.data_io   = (unsigned long) hp_sdc.base_io + 1;
    hp_sdc.status_io = (unsigned long) hp_sdc.base_io + 3;
    fs = get_fs();
    set_fs(KERNEL_DS);
    if (!get_user(i, (unsigned char *)hp_sdc.data_io))
        hp_sdc.dev = (void *)1;
    set_fs(fs);
    hp_sdc.dev_err   = hp_sdc_init();
#endif
    if (hp_sdc.dev == NULL) {
        printk(KERN_WARNING PREFIX "No SDC found.\n");
        return hp_sdc.dev_err;
    }

    sema_init(&tq_init_sem, 0);

    tq_init.actidx      = 0;
    tq_init.idx     = 1;
    tq_init.endidx      = 5;
    tq_init.seq     = tq_init_seq;
    tq_init.act.semaphore   = &tq_init_sem;

    tq_init_seq[0] =
        HP_SDC_ACT_POSTCMD | HP_SDC_ACT_DATAIN | HP_SDC_ACT_SEMAPHORE;
    tq_init_seq[1] = HP_SDC_CMD_READ_KCC;
    tq_init_seq[2] = 1;
    tq_init_seq[3] = 0;
    tq_init_seq[4] = 0;

    hp_sdc_enqueue_transaction(&tq_init);

    down(&tq_init_sem);
    up(&tq_init_sem);

    if ((tq_init_seq[0] & HP_SDC_ACT_DEAD) == HP_SDC_ACT_DEAD) {
        printk(KERN_WARNING PREFIX "Error reading config byte.\n");
        hp_sdc_exit();
        return -ENODEV;
    }
    hp_sdc.r11 = tq_init_seq[4];
    if (hp_sdc.r11 & HP_SDC_CFG_NEW) {
        const char *str;
        printk(KERN_INFO PREFIX "New style SDC\n");
        tq_init_seq[1] = HP_SDC_CMD_READ_XTD;
        tq_init.actidx      = 0;
        tq_init.idx     = 1;
        down(&tq_init_sem);
        hp_sdc_enqueue_transaction(&tq_init);
        down(&tq_init_sem);
        up(&tq_init_sem);
        if ((tq_init_seq[0] & HP_SDC_ACT_DEAD) == HP_SDC_ACT_DEAD) {
            printk(KERN_WARNING PREFIX "Error reading extended config byte.\n");
            return -ENODEV;
        }
        hp_sdc.r7e = tq_init_seq[4];
        HP_SDC_XTD_REV_STRINGS(hp_sdc.r7e & HP_SDC_XTD_REV, str)
        printk(KERN_INFO PREFIX "Revision: %s\n", str);
        if (hp_sdc.r7e & HP_SDC_XTD_BEEPER)
            printk(KERN_INFO PREFIX "TI SN76494 beeper present\n");
        if (hp_sdc.r7e & HP_SDC_XTD_BBRTC)
            printk(KERN_INFO PREFIX "OKI MSM-58321 BBRTC present\n");
        printk(KERN_INFO PREFIX "Spunking the self test register to force PUP "
               "on next firmware reset.\n");
        tq_init_seq[0] = HP_SDC_ACT_PRECMD |
            HP_SDC_ACT_DATAOUT | HP_SDC_ACT_SEMAPHORE;
        tq_init_seq[1] = HP_SDC_CMD_SET_STR;
        tq_init_seq[2] = 1;
        tq_init_seq[3] = 0;
        tq_init.actidx      = 0;
        tq_init.idx     = 1;
        tq_init.endidx      = 4;
        down(&tq_init_sem);
        hp_sdc_enqueue_transaction(&tq_init);
        down(&tq_init_sem);
        up(&tq_init_sem);
    } else
        printk(KERN_INFO PREFIX "Old style SDC (1820-%s).\n",
               (hp_sdc.r11 & HP_SDC_CFG_REV) ? "3300" : "2564/3087");

        return 0;
}

module_init(hp_sdc_register);
module_exit(hp_sdc_exit);

/* Timing notes:  These measurements taken on my 64MHz 7100-LC (715/64)
 *                                              cycles cycles-adj    time
 * between two consecutive mfctl(16)'s:              4        n/a    63ns
 * hp_sdc_spin_ibf when idle:                      119        115   1.7us
 * gsc_writeb status register:                      83         79   1.2us
 * IBF to clear after sending SET_IM:             6204       6006    93us
 * IBF to clear after sending LOAD_RT:            4467       4352    68us
 * IBF to clear after sending two LOAD_RTs:      18974      18859   295us
 * READ_T1, read status/data, IRQ, call handler: 35564        n/a   556us
 * cmd to ~IBF READ_T1 2nd time right after:   5158403        n/a    81ms
 * between IRQ received and ~IBF for above:    2578877        n/a    40ms
 *
 * Performance stats after a run of this module configuring HIL and
 * receiving a few mouse events:
 *
 * status in8  282508 cycles 7128 calls
 * status out8   8404 cycles  341 calls
 * data out8     1734 cycles   78 calls
 * isr         174324 cycles  617 calls (includes take)
 * take          1241 cycles    2 calls
 * put        1411504 cycles 6937 calls
 * task       1655209 cycles 6937 calls (includes put)
 *
 */