/*
 * Copyright (c) 1994 John S. Dyson
 * 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 immediately at the beginning of the file, without modification,
 *    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. Absolutely no warranty of function or purpose is made by the author
 *    John S. Dyson.
 * 4. Modifications may be freely made to this file if the above conditions
 *    are met.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/buf.h>
#include <sys/conf.h>
#include <sys/proc.h>
#include <sys/uio.h>
#include <sys/device.h>

#include <vm/vm.h>
#include <vm/vm_extern.h>

static int
physio(cdev_t dev, struct uio *uio, int ioflag)
{
        int i;
        int error;
        int saflags;
        size_t iolen;
        size_t bcount;
        caddr_t ubase;
        struct buf *bp;

        if (uio->uio_segflg == UIO_USERSPACE)
                bp = getpbuf_mem(NULL);
        else
                bp = getpbuf_kva(NULL);
        saflags = bp->b_flags;
        error = 0;

        /* XXX: sanity check */
        if (dev->si_iosize_max < PAGE_SIZE) {
                kprintf("WARNING: %s si_iosize_max=%d, using MAXPHYS.\n",
                    devtoname(dev), dev->si_iosize_max);
                dev->si_iosize_max = MAXPHYS;
        }

        /* Must be a real uio */
        KKASSERT(uio->uio_segflg != UIO_NOCOPY);

        for (i = 0; i < uio->uio_iovcnt; i++) {
                while (uio->uio_iov[i].iov_len) {
                        if (uio->uio_rw == UIO_READ)
                                bp->b_cmd = BUF_CMD_READ;
                        else 
                                bp->b_cmd = BUF_CMD_WRITE;
                        bp->b_flags = saflags;
                        bcount = uio->uio_iov[i].iov_len;

                        reinitbufbio(bp);       /* clear translation cache */
                        bp->b_bio1.bio_offset = uio->uio_offset;
                        bp->b_bio1.bio_done = biodone_sync;
                        bp->b_bio1.bio_flags |= BIO_SYNC;

                        /* 
                         * Setup for mapping the request into kernel memory.
                         *
                         * We can only write as much as fits in a pbuf,
                         * which is MAXPHYS, and no larger then the device's
                         * ability.
                         *
                         * If not using bounce pages the base address of the
                         * user mapping into the pbuf may be offset, further
                         * reducing how much will actually fit in the pbuf.
                         */
                        if (bcount > dev->si_iosize_max)
                                bcount = dev->si_iosize_max;

                        ubase = uio->uio_iov[i].iov_base;
                        iolen = ((vm_offset_t)ubase) & PAGE_MASK;
                        if (bcount > bp->b_kvasize)
                                bcount = bp->b_kvasize;

                        /*
                         * If we have to use a bounce buffer allocate kernel
                         * memory and copyin/copyout.  Otherwise map the
                         * user buffer directly into kernel memory without
                         * copying.
                         */
                        if (uio->uio_segflg == UIO_USERSPACE) {
                                bp->b_bcount = bcount;
                                if (uio->uio_rw == UIO_WRITE) {
                                        error = copyin(ubase, bp->b_data, bcount);
                                        if (error)
                                                goto doerror;
                                }
                        } else {
                                bp->b_data = uio->uio_iov[i].iov_base;
                                bp->b_bcount = bcount;
                        }
                        dev_dstrategy(dev, &bp->b_bio1);
                        biowait(&bp->b_bio1, "physstr");

                        iolen = bp->b_bcount - bp->b_resid;
                        if (uio->uio_segflg == UIO_USERSPACE) {
                                if (uio->uio_rw == UIO_READ && iolen) {
                                        error = copyout(bp->b_data, ubase, iolen);
                                        if (error) {
                                                bp->b_flags |= B_ERROR;
                                                bp->b_error = error;
                                        }
                                }
                        }
                        if (iolen == 0 && !(bp->b_flags & B_ERROR))
                                goto doerror;   /* EOF */
                        uio->uio_iov[i].iov_len -= iolen;
                        uio->uio_iov[i].iov_base = (char *)uio->uio_iov[i].iov_base + iolen;
                        uio->uio_resid -= iolen;
                        uio->uio_offset += iolen;
                        if (bp->b_flags & B_ERROR) {
                                error = bp->b_error;
                                goto doerror;
                        }
                }
        }
doerror:
        relpbuf(bp, NULL);
        return (error);
}

int
physread(struct dev_read_args *ap)
{
        return(physio(ap->a_head.a_dev, ap->a_uio, ap->a_ioflag));
}

int
physwrite(struct dev_write_args *ap)
{
        return(physio(ap->a_head.a_dev, ap->a_uio, ap->a_ioflag));
}