/* $NetBSD: isadma_bounce.c,v 1.17 2022/01/22 15:10:30 skrll Exp $ */

/*-
 * Copyright (c) 1996, 1997, 1998, 2000 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
 * NASA Ames Research Center.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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>                  /* RCS ID & Copyright macro defns */

__KERNEL_RCSID(0, "$NetBSD: isadma_bounce.c,v 1.17 2022/01/22 15:10:30 skrll Exp $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/syslog.h>
#include <sys/device.h>
#include <sys/kmem.h>
#include <sys/proc.h>
#include <sys/mbuf.h>

#define _ALPHA_BUS_DMA_PRIVATE
#include <sys/bus.h>

#include <dev/isa/isareg.h>
#include <dev/isa/isavar.h>

extern  paddr_t avail_end;

/*
 * Cookie used by bouncing ISA DMA.  A pointer to one of these is stashed
 * in the DMA map.
 */
struct isadma_bounce_cookie {
        int     id_flags;               /* flags; see below */

        /*
         * Information about the original buffer used during
         * DMA map syncs.  Note that origbuflen is only used
         * for ID_BUFTYPE_LINEAR.
         */
        void    *id_origbuf;            /* pointer to orig buffer if
                                           bouncing */
        bus_size_t id_origbuflen;       /* ...and size */
        int     id_buftype;             /* type of buffer */

        void    *id_bouncebuf;          /* pointer to the bounce buffer */
        bus_size_t id_bouncebuflen;     /* ...and size */
        int     id_nbouncesegs;         /* number of valid bounce segs */
        bus_dma_segment_t id_bouncesegs[1]; /* array of bounce buffer
                                               physical memory segments */
};

/* id_flags */
#define ID_MIGHT_NEED_BOUNCE    0x01    /* map could need bounce buffers */
#define ID_HAS_BOUNCE           0x02    /* map currently has bounce buffers */
#define ID_IS_BOUNCING          0x04    /* map is bouncing current xfer */

/* id_buftype */
#define ID_BUFTYPE_INVALID      0
#define ID_BUFTYPE_LINEAR       1
#define ID_BUFTYPE_MBUF         2
#define ID_BUFTYPE_UIO          3
#define ID_BUFTYPE_RAW          4

static int      isadma_bounce_alloc_bouncebuf(bus_dma_tag_t, bus_dmamap_t,
                    bus_size_t, int);
static void     isadma_bounce_free_bouncebuf(bus_dma_tag_t, bus_dmamap_t);

/*
 * Returns true if the system memory configuration exceeds the
 * capabilities of ISA DMA.
 */
static bool
isadma_bounce_check_range(bus_dma_tag_t const t)
{
        return avail_end > (t->_wbase + t->_wsize);
}

static int
isadma_bounce_cookieflags(bus_dma_tag_t const t, bus_dmamap_t const map)
{
        int cookieflags = 0;

        /*
         * ISA only has 24-bits of address space.  This means
         * we can't DMA to pages over 16M.  In order to DMA to
         * arbitrary buffers, we use "bounce buffers" - pages
         * in memory below the 16M boundary.  On DMA reads,
         * DMA happens to the bounce buffers, and is copied into
         * the caller's buffer.  On writes, data is copied into
         * the bounce buffer, and the DMA happens from those
         * pages.  To software using the DMA mapping interface,
         * this looks simply like a data cache.
         *
         * If we have more than 16M of RAM in the system, we may
         * need bounce buffers.  We check and remember that here.
         *
         * ...or, there is an opposite case.  The most segments
         * a transfer will require is (maxxfer / PAGE_SIZE) + 1.  If
         * the caller can't handle that many segments (e.g. the
         * ISA DMA controller), we may have to bounce it as well.
         */
        if (isadma_bounce_check_range(t) ||
            ((map->_dm_size / PAGE_SIZE) + 1) > map->_dm_segcnt) {
                cookieflags |= ID_MIGHT_NEED_BOUNCE;
        }
        return cookieflags;
}

static size_t
isadma_bounce_cookiesize(bus_dmamap_t const map, int cookieflags)
{
        size_t cookiesize = sizeof(struct isadma_bounce_cookie);

        if (cookieflags & ID_MIGHT_NEED_BOUNCE) {
                cookiesize += (sizeof(bus_dma_segment_t) *
                    (map->_dm_segcnt - 1));
        }
        return cookiesize;
}

static int
isadma_bounce_cookie_alloc(bus_dma_tag_t const t, bus_dmamap_t const map,
    int const flags)
{
        struct isadma_bounce_cookie *cookie;
        int cookieflags = isadma_bounce_cookieflags(t, map);

        if ((cookie = kmem_zalloc(isadma_bounce_cookiesize(map, cookieflags),
             (flags & BUS_DMA_NOWAIT) ? KM_NOSLEEP : KM_SLEEP)) == NULL) {
                return ENOMEM;
        }

        cookie->id_flags = cookieflags;
        map->_dm_cookie = cookie;

        return 0;
}

static void
isadma_bounce_cookie_free(bus_dmamap_t const map)
{
        struct isadma_bounce_cookie *cookie = map->_dm_cookie;

        if (cookie != NULL) {
                kmem_free(map->_dm_cookie,
                    isadma_bounce_cookiesize(map, cookie->id_flags));
                map->_dm_cookie = NULL;
        }
}

/*
 * Create an ISA DMA map.
 */
int
isadma_bounce_dmamap_create(bus_dma_tag_t t, bus_size_t size, int nsegments,
    bus_size_t maxsegsz, bus_size_t boundary, int flags, bus_dmamap_t *dmamp)
{
        struct isadma_bounce_cookie *cookie;
        bus_dmamap_t map;
        int error;

        /* Call common function to create the basic map. */
        error = _bus_dmamap_create(t, size, nsegments, maxsegsz, boundary,
            flags, dmamp);
        if (error)
                return (error);

        map = *dmamp;
        map->_dm_cookie = NULL;

        /*
         * Allocate our cookie.
         */
        if ((error = isadma_bounce_cookie_alloc(t, map, flags)) != 0) {
                goto out;
        }
        cookie = map->_dm_cookie;

        if (cookie->id_flags & ID_MIGHT_NEED_BOUNCE) {
                /*
                 * Allocate the bounce pages now if the caller
                 * wishes us to do so.
                 */
                if (flags & BUS_DMA_ALLOCNOW) {
                        error = isadma_bounce_alloc_bouncebuf(t, map, size,
                            flags);
                }
        }

 out:
        if (error) {
                isadma_bounce_cookie_free(map);
                _bus_dmamap_destroy(t, map);
        }
        return (error);
}

/*
 * Destroy an ISA DMA map.
 */
void
isadma_bounce_dmamap_destroy(bus_dma_tag_t t, bus_dmamap_t map)
{
        struct isadma_bounce_cookie *cookie = map->_dm_cookie;

        /*
         * Free any bounce pages this map might hold.
         */
        if (cookie->id_flags & ID_HAS_BOUNCE)
                isadma_bounce_free_bouncebuf(t, map);

        isadma_bounce_cookie_free(map);
        _bus_dmamap_destroy(t, map);
}

/*
 * Load an ISA DMA map with a linear buffer.
 */
int
isadma_bounce_dmamap_load(bus_dma_tag_t t, bus_dmamap_t map, void *buf,
    size_t buflen, struct proc *p, int flags)
{
        struct isadma_bounce_cookie *cookie = map->_dm_cookie;
        int error;

        /*
         * Make sure that on error condition we return "no valid mappings."
         */
        map->dm_mapsize = 0;
        map->dm_nsegs = 0;

        /*
         * Try to load the map the normal way.  If this errors out,
         * and we can bounce, we will.
         */
        error = _bus_dmamap_load_direct(t, map, buf, buflen, p, flags);
        if (error == 0 || (cookie->id_flags & ID_MIGHT_NEED_BOUNCE) == 0)
                return (error);

        /*
         * First attempt failed; bounce it.
         */

        /*
         * Allocate bounce pages, if necessary.
         */
        if ((cookie->id_flags & ID_HAS_BOUNCE) == 0) {
                error = isadma_bounce_alloc_bouncebuf(t, map, buflen, flags);
                if (error)
                        return (error);
        }

        /*
         * Cache a pointer to the caller's buffer and load the DMA map
         * with the bounce buffer.
         */
        cookie->id_origbuf = buf;
        cookie->id_origbuflen = buflen;
        cookie->id_buftype = ID_BUFTYPE_LINEAR;
        error = _bus_dmamap_load_direct(t, map, cookie->id_bouncebuf, buflen,
            p, flags);
        if (error) {
                /*
                 * Free the bounce pages, unless our resources
                 * are reserved for our exclusive use.
                 */
                if ((map->_dm_flags & BUS_DMA_ALLOCNOW) == 0)
                        isadma_bounce_free_bouncebuf(t, map);
                return (error);
        }

        /* ...so isadma_bounce_dmamap_sync() knows we're bouncing */
        cookie->id_flags |= ID_IS_BOUNCING;
        map->_dm_window = t;
        return (0);
}

/*
 * Like isadma_bounce_dmamap_load(), but for mbufs.
 */
int
isadma_bounce_dmamap_load_mbuf(bus_dma_tag_t t, bus_dmamap_t map,
    struct mbuf *m0, int flags)
{
        struct isadma_bounce_cookie *cookie = map->_dm_cookie;
        int error;

        /*
         * Make sure on error condition we return "no valid mappings."
         */
        map->dm_mapsize = 0;
        map->dm_nsegs = 0;

#ifdef DIAGNOSTIC
        if ((m0->m_flags & M_PKTHDR) == 0)
                panic("isadma_bounce_dmamap_load_mbuf: no packet header");
#endif

        if (m0->m_pkthdr.len > map->_dm_size)
                return (EINVAL);

        /*
         * Try to load the map the normal way.  If this errors out,
         * and we can bounce, we will.
         */
        error = _bus_dmamap_load_mbuf_direct(t, map, m0, flags);
        if (error == 0 || (cookie->id_flags & ID_MIGHT_NEED_BOUNCE) == 0)
                return (error);

        /*
         * First attempt failed; bounce it.
         */

        /*
         * Allocate bounce pages, if necessary.
         */
        if ((cookie->id_flags & ID_HAS_BOUNCE) == 0) {
                error = isadma_bounce_alloc_bouncebuf(t, map, m0->m_pkthdr.len,
                    flags);
                if (error)
                        return (error);
        }

        /*
         * Cache a pointer to the caller's buffer and load the DMA map
         * with the bounce buffer.
         */
        cookie->id_origbuf = m0;
        cookie->id_origbuflen = m0->m_pkthdr.len;       /* not really used */
        cookie->id_buftype = ID_BUFTYPE_MBUF;
        error = _bus_dmamap_load_direct(t, map, cookie->id_bouncebuf,
            m0->m_pkthdr.len, NULL, flags);
        if (error) {
                /*
                 * Free the bounce pages, unless our resources
                 * are reserved for our exclusive use.
                 */
                if ((map->_dm_flags & BUS_DMA_ALLOCNOW) == 0)
                        isadma_bounce_free_bouncebuf(t, map);
                return (error);
        }

        /* ...so isadma_bounce_dmamap_sync() knows we're bouncing */
        cookie->id_flags |= ID_IS_BOUNCING;
        map->_dm_window = t;
        return (0);
}

/*
 * Like isadma_bounce_dmamap_load(), but for uios.
 */
int
isadma_bounce_dmamap_load_uio(bus_dma_tag_t t, bus_dmamap_t map,
    struct uio *uio, int flags)
{

        panic("isadma_bounce_dmamap_load_uio: not implemented");
}

/*
 * Like isadma_bounce_dmamap_load(), but for raw memory allocated with
 * bus_dmamem_alloc().
 */
int
isadma_bounce_dmamap_load_raw(bus_dma_tag_t t, bus_dmamap_t map,
    bus_dma_segment_t *segs, int nsegs, bus_size_t size, int flags)
{

        panic("isadma_bounce_dmamap_load_raw: not implemented");
}

/*
 * Unload an ISA DMA map.
 */
void
isadma_bounce_dmamap_unload(bus_dma_tag_t t, bus_dmamap_t map)
{
        struct isadma_bounce_cookie *cookie = map->_dm_cookie;

        /*
         * If we have bounce pages, free them, unless they're
         * reserved for our exclusive use.
         */
        if ((cookie->id_flags & ID_HAS_BOUNCE) &&
            (map->_dm_flags & BUS_DMA_ALLOCNOW) == 0)
                isadma_bounce_free_bouncebuf(t, map);

        cookie->id_flags &= ~ID_IS_BOUNCING;
        cookie->id_buftype = ID_BUFTYPE_INVALID;

        /*
         * Do the generic bits of the unload.
         */
        _bus_dmamap_unload(t, map);
}

/*
 * Synchronize an ISA DMA map.
 */
void
isadma_bounce_dmamap_sync(bus_dma_tag_t t, bus_dmamap_t map, bus_addr_t offset,
    bus_size_t len, int ops)
{
        struct isadma_bounce_cookie *cookie = map->_dm_cookie;

        /*
         * Mixing PRE and POST operations is not allowed.
         */
        if ((ops & (BUS_DMASYNC_PREREAD|BUS_DMASYNC_PREWRITE)) != 0 &&
            (ops & (BUS_DMASYNC_POSTREAD|BUS_DMASYNC_POSTWRITE)) != 0)
                panic("isadma_bounce_dmamap_sync: mix PRE and POST");

#ifdef DIAGNOSTIC
        if ((ops & (BUS_DMASYNC_PREWRITE|BUS_DMASYNC_POSTREAD)) != 0) {
                if (offset >= map->dm_mapsize)
                        panic("isadma_bounce_dmamap_sync: bad offset");
                if (len == 0 || (offset + len) > map->dm_mapsize)
                        panic("isadma_bounce_dmamap_sync: bad length");
        }
#endif

        /*
         * If we're not bouncing, just drain the write buffer
         * and return.
         */
        if ((cookie->id_flags & ID_IS_BOUNCING) == 0) {
                alpha_mb();
                return;
        }

        switch (cookie->id_buftype) {
        case ID_BUFTYPE_LINEAR:
                /*
                 * Nothing to do for pre-read.
                 */

                if (ops & BUS_DMASYNC_PREWRITE) {
                        /*
                         * Copy the caller's buffer to the bounce buffer.
                         */
                        memcpy((char *)cookie->id_bouncebuf + offset,
                            (char *)cookie->id_origbuf + offset, len);
                }

                if (ops & BUS_DMASYNC_POSTREAD) {
                        /*
                         * Copy the bounce buffer to the caller's buffer.
                         */
                        memcpy((char *)cookie->id_origbuf + offset,
                            (char *)cookie->id_bouncebuf + offset, len);
                }

                /*
                 * Nothing to do for post-write.
                 */
                break;

        case ID_BUFTYPE_MBUF:
            {
                struct mbuf *m, *m0 = cookie->id_origbuf;
                bus_size_t minlen, moff;

                /*
                 * Nothing to do for pre-read.
                 */

                if (ops & BUS_DMASYNC_PREWRITE) {
                        /*
                         * Copy the caller's buffer to the bounce buffer.
                         */
                        m_copydata(m0, offset, len,
                            (char *)cookie->id_bouncebuf + offset);
                }

                if (ops & BUS_DMASYNC_POSTREAD) {
                        /*
                         * Copy the bounce buffer to the caller's buffer.
                         */
                        for (moff = offset, m = m0; m != NULL && len != 0;
                             m = m->m_next) {
                                /* Find the beginning mbuf. */
                                if (moff >= m->m_len) {
                                        moff -= m->m_len;
                                        continue;
                                }

                                /*
                                 * Now at the first mbuf to sync; nail
                                 * each one until we have exhausted the
                                 * length.
                                 */
                                minlen = len < m->m_len - moff ?
                                    len : m->m_len - moff;

                                memcpy(mtod(m, char *) + moff,
                                    (char *)cookie->id_bouncebuf + offset,
                                    minlen);

                                moff = 0;
                                len -= minlen;
                                offset += minlen;
                        }
                }

                /*
                 * Nothing to do for post-write.
                 */
                break;
            }

        case ID_BUFTYPE_UIO:
                panic("isadma_bounce_dmamap_sync: ID_BUFTYPE_UIO");
                break;

        case ID_BUFTYPE_RAW:
                panic("isadma_bounce_dmamap_sync: ID_BUFTYPE_RAW");
                break;

        case ID_BUFTYPE_INVALID:
                panic("isadma_bounce_dmamap_sync: ID_BUFTYPE_INVALID");
                break;

        default:
                printf("unknown buffer type %d\n", cookie->id_buftype);
                panic("isadma_bounce_dmamap_sync");
        }

        /* Drain the write buffer. */
        alpha_mb();
}

/*
 * Allocate memory safe for ISA DMA.
 */
int
isadma_bounce_dmamem_alloc(bus_dma_tag_t t, bus_size_t size,
    bus_size_t alignment, bus_size_t boundary, bus_dma_segment_t *segs,
    int nsegs, int *rsegs, int flags)
{
        paddr_t high;

        if (avail_end > ISA_DMA_BOUNCE_THRESHOLD)
                high = ISA_DMA_BOUNCE_THRESHOLD - 1;
        else
                high = avail_end - 1;

        return (_bus_dmamem_alloc_range(t, size, alignment, boundary,
            segs, nsegs, rsegs, flags, 0, high));
}

/**********************************************************************
 * ISA DMA utility functions
 **********************************************************************/

static int
isadma_bounce_alloc_bouncebuf(bus_dma_tag_t t, bus_dmamap_t map,
    bus_size_t size, int flags)
{
        struct isadma_bounce_cookie *cookie = map->_dm_cookie;
        int error = 0;

        cookie->id_bouncebuflen = round_page(size);
        error = isadma_bounce_dmamem_alloc(t, cookie->id_bouncebuflen,
            PAGE_SIZE, map->_dm_boundary, cookie->id_bouncesegs,
            map->_dm_segcnt, &cookie->id_nbouncesegs, flags);
        if (error)
                goto out;
        error = _bus_dmamem_map(t, cookie->id_bouncesegs,
            cookie->id_nbouncesegs, cookie->id_bouncebuflen,
            (void **)&cookie->id_bouncebuf, flags);

 out:
        if (error) {
                _bus_dmamem_free(t, cookie->id_bouncesegs,
                    cookie->id_nbouncesegs);
                cookie->id_bouncebuflen = 0;
                cookie->id_nbouncesegs = 0;
        } else
                cookie->id_flags |= ID_HAS_BOUNCE;

        return (error);
}

static void
isadma_bounce_free_bouncebuf(bus_dma_tag_t t, bus_dmamap_t map)
{
        struct isadma_bounce_cookie *cookie = map->_dm_cookie;

        _bus_dmamem_unmap(t, cookie->id_bouncebuf,
            cookie->id_bouncebuflen);
        _bus_dmamem_free(t, cookie->id_bouncesegs,
            cookie->id_nbouncesegs);
        cookie->id_bouncebuflen = 0;
        cookie->id_nbouncesegs = 0;
        cookie->id_flags &= ~ID_HAS_BOUNCE;
}