/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1991 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * William Jolitz.
 *
 * 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.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
/*
 * code to manage AT bus
 *
 * 92/08/18  Frank P. MacLachlan (fpm@crash.cts.com):
 * Fixed uninitialized variable problem and added code to deal
 * with DMA page boundaries in isa_dmarangecheck().  Fixed word
 * mode DMA count compution and reorganized DMA setup code in
 * isa_dmastart()
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bus.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/lock.h>
#include <sys/proc.h>
#include <sys/mutex.h>
#include <sys/module.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/pmap.h>
#include <isa/isareg.h>
#include <isa/isavar.h>
#include <isa/isa_dmareg.h>

#define ISARAM_END      0x1000000

static int isa_dmarangecheck(caddr_t va, u_int length, int chan);

static caddr_t  dma_bouncebuf[8];
static u_int    dma_bouncebufsize[8];
static u_int8_t dma_bounced = 0;
static u_int8_t dma_busy = 0;           /* Used in isa_dmastart() */
static u_int8_t dma_inuse = 0;          /* User for acquire/release */
static u_int8_t dma_auto_mode = 0;
static struct mtx isa_dma_lock;
MTX_SYSINIT(isa_dma_lock, &isa_dma_lock, "isa DMA lock", MTX_DEF);

#define VALID_DMA_MASK (7)

/* high byte of address is stored in this port for i-th dma channel */
static int dmapageport[8] = { 0x87, 0x83, 0x81, 0x82, 0x8f, 0x8b, 0x89, 0x8a };

/*
 * Setup a DMA channel's bounce buffer.
 */
int
isa_dma_init(int chan, u_int bouncebufsize, int flag)
{
        void *buf;

#ifdef DIAGNOSTIC
        if (chan & ~VALID_DMA_MASK)
                panic("isa_dma_init: channel out of range");
#endif

        /* Try malloc() first.  It works better if it works. */
        buf = malloc(bouncebufsize, M_DEVBUF, flag);
        if (buf != NULL) {
                if (isa_dmarangecheck(buf, bouncebufsize, chan) != 0) {
                        free(buf, M_DEVBUF);
                        buf = NULL;
                }
        }

        if (buf == NULL) {
                buf = contigmalloc(bouncebufsize, M_DEVBUF, flag, 0ul, 0xfffffful,
                           1ul, chan & 4 ? 0x20000ul : 0x10000ul);
        }

        if (buf == NULL)
                return (ENOMEM);

        mtx_lock(&isa_dma_lock);
        /*
         * If a DMA channel is shared, both drivers have to call isa_dma_init
         * since they don't know that the other driver will do it.
         * Just return if we're already set up good.
         * XXX: this only works if they agree on the bouncebuf size.  This
         * XXX: is typically the case since they are multiple instances of
         * XXX: the same driver.
         */
        if (dma_bouncebuf[chan] != NULL) {
                free(buf, M_DEVBUF);
                mtx_unlock(&isa_dma_lock);
                return (0);
        }

        dma_bouncebufsize[chan] = bouncebufsize;
        dma_bouncebuf[chan] = buf;

        mtx_unlock(&isa_dma_lock);

        return (0);
}

/*
 * Register a DMA channel's usage.  Usually called from a device driver
 * in open() or during its initialization.
 */
int
isa_dma_acquire(int chan)
{
#ifdef DIAGNOSTIC
        if (chan & ~VALID_DMA_MASK)
                panic("isa_dma_acquire: channel out of range");
#endif

        mtx_lock(&isa_dma_lock);
        if (dma_inuse & (1 << chan)) {
                printf("isa_dma_acquire: channel %d already in use\n", chan);
                mtx_unlock(&isa_dma_lock);
                return (EBUSY);
        }
        dma_inuse |= (1 << chan);
        dma_auto_mode &= ~(1 << chan);
        mtx_unlock(&isa_dma_lock);

        return (0);
}

/*
 * Unregister a DMA channel's usage.  Usually called from a device driver
 * during close() or during its shutdown.
 */
void
isa_dma_release(int chan)
{
#ifdef DIAGNOSTIC
        if (chan & ~VALID_DMA_MASK)
                panic("isa_dma_release: channel out of range");

        mtx_lock(&isa_dma_lock);
        if ((dma_inuse & (1 << chan)) == 0)
                printf("isa_dma_release: channel %d not in use\n", chan);
#else
        mtx_lock(&isa_dma_lock);
#endif

        if (dma_busy & (1 << chan)) {
                dma_busy &= ~(1 << chan);
                /* 
                 * XXX We should also do "dma_bounced &= (1 << chan);"
                 * because we are acting on behalf of isa_dmadone() which
                 * was not called to end the last DMA operation.  This does
                 * not matter now, but it may in the future.
                 */
        }

        dma_inuse &= ~(1 << chan);
        dma_auto_mode &= ~(1 << chan);

        mtx_unlock(&isa_dma_lock);
}

/*
 * isa_dmacascade(): program 8237 DMA controller channel to accept
 * external dma control by a board.
 */
void
isa_dmacascade(int chan)
{
#ifdef DIAGNOSTIC
        if (chan & ~VALID_DMA_MASK)
                panic("isa_dmacascade: channel out of range");
#endif

        mtx_lock(&isa_dma_lock);
        /* set dma channel mode, and set dma channel mode */
        if ((chan & 4) == 0) {
                outb(DMA1_MODE, DMA37MD_CASCADE | chan);
                outb(DMA1_SMSK, chan);
        } else {
                outb(DMA2_MODE, DMA37MD_CASCADE | (chan & 3));
                outb(DMA2_SMSK, chan & 3);
        }
        mtx_unlock(&isa_dma_lock);
}

/*
 * isa_dmastart(): program 8237 DMA controller channel, avoid page alignment
 * problems by using a bounce buffer.
 */
void
isa_dmastart(int flags, caddr_t addr, u_int nbytes, int chan)
{
        vm_paddr_t phys;
        int waport;
        caddr_t newaddr;
        int dma_range_checked;

        dma_range_checked = isa_dmarangecheck(addr, nbytes, chan);

#ifdef DIAGNOSTIC
        if (chan & ~VALID_DMA_MASK)
                panic("isa_dmastart: channel out of range");

        if ((chan < 4 && nbytes > (1<<16))
            || (chan >= 4 && (nbytes > (1<<17) || (uintptr_t)addr & 1)))
                panic("isa_dmastart: impossible request");

        mtx_lock(&isa_dma_lock);
        if ((dma_inuse & (1 << chan)) == 0)
                printf("isa_dmastart: channel %d not acquired\n", chan);
#else
        mtx_lock(&isa_dma_lock);
#endif

#if 0
        /*
         * XXX This should be checked, but drivers like ad1848 only call
         * isa_dmastart() once because they use Auto DMA mode.  If we
         * leave this in, drivers that do this will print this continuously.
         */
        if (dma_busy & (1 << chan))
                printf("isa_dmastart: channel %d busy\n", chan);
#endif

        dma_busy |= (1 << chan);

        if (dma_range_checked) {
                if (dma_bouncebuf[chan] == NULL
                    || dma_bouncebufsize[chan] < nbytes)
                        panic("isa_dmastart: bad bounce buffer"); 
                dma_bounced |= (1 << chan);
                newaddr = dma_bouncebuf[chan];

                /* copy bounce buffer on write */
                if (!(flags & ISADMA_READ))
                        bcopy(addr, newaddr, nbytes);
                addr = newaddr;
        }

        /* translate to physical */
        phys = pmap_extract(kernel_pmap, (vm_offset_t)addr);

        if (flags & ISADMA_RAW) {
            dma_auto_mode |= (1 << chan);
        } else { 
            dma_auto_mode &= ~(1 << chan);
        }

        if ((chan & 4) == 0) {
                /*
                 * Program one of DMA channels 0..3.  These are
                 * byte mode channels.
                 */
                /* set dma channel mode, and reset address ff */

                /* If ISADMA_RAW flag is set, then use autoinitialise mode */
                if (flags & ISADMA_RAW) {
                  if (flags & ISADMA_READ)
                        outb(DMA1_MODE, DMA37MD_AUTO|DMA37MD_WRITE|chan);
                  else
                        outb(DMA1_MODE, DMA37MD_AUTO|DMA37MD_READ|chan);
                }
                else
                if (flags & ISADMA_READ)
                        outb(DMA1_MODE, DMA37MD_SINGLE|DMA37MD_WRITE|chan);
                else
                        outb(DMA1_MODE, DMA37MD_SINGLE|DMA37MD_READ|chan);
                outb(DMA1_FFC, 0);

                /* send start address */
                waport =  DMA1_CHN(chan);
                outb(waport, phys);
                outb(waport, phys>>8);
                outb(dmapageport[chan], phys>>16);

                /* send count */
                outb(waport + 1, --nbytes);
                outb(waport + 1, nbytes>>8);

                /* unmask channel */
                outb(DMA1_SMSK, chan);
        } else {
                /*
                 * Program one of DMA channels 4..7.  These are
                 * word mode channels.
                 */
                /* set dma channel mode, and reset address ff */

                /* If ISADMA_RAW flag is set, then use autoinitialise mode */
                if (flags & ISADMA_RAW) {
                  if (flags & ISADMA_READ)
                        outb(DMA2_MODE, DMA37MD_AUTO|DMA37MD_WRITE|(chan&3));
                  else
                        outb(DMA2_MODE, DMA37MD_AUTO|DMA37MD_READ|(chan&3));
                }
                else
                if (flags & ISADMA_READ)
                        outb(DMA2_MODE, DMA37MD_SINGLE|DMA37MD_WRITE|(chan&3));
                else
                        outb(DMA2_MODE, DMA37MD_SINGLE|DMA37MD_READ|(chan&3));
                outb(DMA2_FFC, 0);

                /* send start address */
                waport = DMA2_CHN(chan - 4);
                outb(waport, phys>>1);
                outb(waport, phys>>9);
                outb(dmapageport[chan], phys>>16);

                /* send count */
                nbytes >>= 1;
                outb(waport + 2, --nbytes);
                outb(waport + 2, nbytes>>8);

                /* unmask channel */
                outb(DMA2_SMSK, chan & 3);
        }
        mtx_unlock(&isa_dma_lock);
}

void
isa_dmadone(int flags, caddr_t addr, int nbytes, int chan)
{  
#ifdef DIAGNOSTIC
        if (chan & ~VALID_DMA_MASK)
                panic("isa_dmadone: channel out of range");

        if ((dma_inuse & (1 << chan)) == 0)
                printf("isa_dmadone: channel %d not acquired\n", chan);
#endif

        mtx_lock(&isa_dma_lock);
        if (((dma_busy & (1 << chan)) == 0) && 
            (dma_auto_mode & (1 << chan)) == 0 )
                printf("isa_dmadone: channel %d not busy\n", chan);

        if ((dma_auto_mode & (1 << chan)) == 0)
                outb(chan & 4 ? DMA2_SMSK : DMA1_SMSK, (chan & 3) | 4);

        if (dma_bounced & (1 << chan)) {
                /* copy bounce buffer on read */
                if (flags & ISADMA_READ)
                        bcopy(dma_bouncebuf[chan], addr, nbytes);

                dma_bounced &= ~(1 << chan);
        }
        dma_busy &= ~(1 << chan);
        mtx_unlock(&isa_dma_lock);
}

/*
 * Check for problems with the address range of a DMA transfer
 * (non-contiguous physical pages, outside of bus address space,
 * crossing DMA page boundaries).
 * Return true if special handling needed.
 */

static int
isa_dmarangecheck(caddr_t va, u_int length, int chan)
{
        vm_paddr_t phys, priorpage = 0;
        vm_offset_t endva;
        u_int dma_pgmsk = (chan & 4) ?  ~(128*1024-1) : ~(64*1024-1);

        endva = (vm_offset_t)round_page((vm_offset_t)va + length);
        for (; va < (caddr_t) endva ; va += PAGE_SIZE) {
                phys = trunc_page(pmap_extract(kernel_pmap, (vm_offset_t)va));
                if (phys == 0)
                        panic("isa_dmacheck: no physical page present");
                if (phys >= ISARAM_END)
                        return (1);
                if (priorpage) {
                        if (priorpage + PAGE_SIZE != phys)
                                return (1);
                        /* check if crossing a DMA page boundary */
                        if (((u_int)priorpage ^ (u_int)phys) & dma_pgmsk)
                                return (1);
                }
                priorpage = phys;
        }
        return (0);
}

/*
 * Query the progress of a transfer on a DMA channel.
 *
 * To avoid having to interrupt a transfer in progress, we sample
 * each of the high and low databytes twice, and apply the following
 * logic to determine the correct count.
 *
 * Reads are performed with interrupts disabled, thus it is to be
 * expected that the time between reads is very small.  At most
 * one rollover in the low count byte can be expected within the
 * four reads that are performed.
 *
 * There are three gaps in which a rollover can occur :
 *
 * - read low1
 *              gap1
 * - read high1
 *              gap2
 * - read low2
 *              gap3
 * - read high2
 *
 * If a rollover occurs in gap1 or gap2, the low2 value will be
 * greater than the low1 value.  In this case, low2 and high2 are a
 * corresponding pair. 
 *
 * In any other case, low1 and high1 can be considered to be correct.
 *
 * The function returns the number of bytes remaining in the transfer,
 * or -1 if the channel requested is not active.
 *
 */
static int
isa_dmastatus_locked(int chan)
{
        u_long  cnt = 0;
        int     ffport, waport;
        u_long  low1, high1, low2, high2;

        mtx_assert(&isa_dma_lock, MA_OWNED);

        /* channel active? */
        if ((dma_inuse & (1 << chan)) == 0) {
                printf("isa_dmastatus: channel %d not active\n", chan);
                return(-1);
        }
        /* channel busy? */

        if (((dma_busy & (1 << chan)) == 0) &&
            (dma_auto_mode & (1 << chan)) == 0 ) {
            printf("chan %d not busy\n", chan);
            return -2 ;
        }       
        if (chan < 4) {                 /* low DMA controller */
                ffport = DMA1_FFC;
                waport = DMA1_CHN(chan) + 1;
        } else {                        /* high DMA controller */
                ffport = DMA2_FFC;
                waport = DMA2_CHN(chan - 4) + 2;
        }

        disable_intr();                 /* no interrupts Mr Jones! */
        outb(ffport, 0);                /* clear register LSB flipflop */
        low1 = inb(waport);
        high1 = inb(waport);
        outb(ffport, 0);                /* clear again */
        low2 = inb(waport);
        high2 = inb(waport);
        enable_intr();                  /* enable interrupts again */

        /* 
         * Now decide if a wrap has tried to skew our results.
         * Note that after TC, the count will read 0xffff, while we want 
         * to return zero, so we add and then mask to compensate.
         */
        if (low1 >= low2) {
                cnt = (low1 + (high1 << 8) + 1) & 0xffff;
        } else {
                cnt = (low2 + (high2 << 8) + 1) & 0xffff;
        }

        if (chan >= 4)                  /* high channels move words */
                cnt *= 2;
        return(cnt);
}

int
isa_dmastatus(int chan)
{
        int status;

        mtx_lock(&isa_dma_lock);
        status = isa_dmastatus_locked(chan);
        mtx_unlock(&isa_dma_lock);

        return (status);
}

/*
 * Reached terminal count yet ?
 */
int
isa_dmatc(int chan)
{

        if (chan < 4)
                return(inb(DMA1_STATUS) & (1 << chan));
        else
                return(inb(DMA2_STATUS) & (1 << (chan & 3)));
}

/*
 * Stop a DMA transfer currently in progress.
 */
int
isa_dmastop(int chan) 
{
        int status;

        mtx_lock(&isa_dma_lock);
        if ((dma_inuse & (1 << chan)) == 0)
                printf("isa_dmastop: channel %d not acquired\n", chan);  

        if (((dma_busy & (1 << chan)) == 0) &&
            ((dma_auto_mode & (1 << chan)) == 0)) {
                printf("chan %d not busy\n", chan);
                mtx_unlock(&isa_dma_lock);
                return -2 ;
        }
    
        if ((chan & 4) == 0) {
                outb(DMA1_SMSK, (chan & 3) | 4 /* disable mask */);
        } else {
                outb(DMA2_SMSK, (chan & 3) | 4 /* disable mask */);
        }

        status = isa_dmastatus_locked(chan);

        mtx_unlock(&isa_dma_lock);

        return (status);
}

/*
 * Attach to the ISA PnP descriptor for the AT DMA controller
 */
static struct isa_pnp_id atdma_ids[] = {
        { 0x0002d041 /* PNP0200 */, "AT DMA controller" },
        { 0 }
};

static int
atdma_probe(device_t dev)
{
        int result;

        if ((result = ISA_PNP_PROBE(device_get_parent(dev), dev, atdma_ids)) <= 0)
                device_quiet(dev);
        return(result);
}

static int
atdma_attach(device_t dev)
{
        return(0);
}

static device_method_t atdma_methods[] = {
        /* Device interface */
        DEVMETHOD(device_probe,         atdma_probe),
        DEVMETHOD(device_attach,        atdma_attach),
        { 0, 0 }
};

static driver_t atdma_driver = {
        "atdma",
        atdma_methods,
        1,              /* no softc */
};

DRIVER_MODULE(atdma, isa, atdma_driver, 0, 0);
DRIVER_MODULE(atdma, acpi, atdma_driver, 0, 0);
ISA_PNP_INFO(atdma_ids);