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 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
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/*-
 * Copyright (c) 1982, 1986, 1990, 1993
 *      The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. 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.
 *
 *      from: @(#)kern_physio.c 8.1 (Berkeley) 6/10/93
 */
/*
 * HISTORY
 * 27-July-97  Umesh Vaishampayan  (umeshv@apple.com)
 *      Allow physio() to kernel space.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/buf_internal.h>
#include <sys/conf.h>
#include <sys/proc_internal.h>
#include <sys/uio_internal.h>

int
physio(strategy, bp, dev, flags, minphys, uio, blocksize)
        void (*strategy)(); 
        buf_t bp;
        dev_t dev;
        int flags;
        u_int (*minphys)();
        struct uio *uio;
        int blocksize;
{
        struct proc *p = current_proc();
        int error, i, nobuf, todo, iosize;
#if LP64KERN
        int64_t done;
#else
        int done;
#endif

        error = 0;
        flags &= B_READ | B_WRITE;

        /*
         * [check user read/write access to the data buffer]
         *
         * Check each iov one by one.  Note that we know if we're reading or
         * writing, so we ignore the uio's rw parameter.  Also note that if
         * we're doing a read, that's a *write* to user-space.
         */
        for (i = 0; i < uio->uio_iovcnt; i++) {
                if(UIO_SEG_IS_USER_SPACE(uio->uio_segflg)) {
                        if (!useracc(uio_iov_base_at(uio, i),
                                        uio_iov_len_at(uio, i),
                                (flags == B_READ) ? B_WRITE : B_READ))
                        return (EFAULT);
                }
        }
        /* Make sure we have a buffer, creating one if necessary. */
        if (nobuf = (bp == NULL)) {
                        bp = buf_alloc((vnode_t)0);
                }

        /* [while the buffer is marked busy] */
        while (((error = (int)buf_acquire(bp, 0, 0, 0)) == EAGAIN));
        
        if (error) {
                        if (nobuf)
                                buf_free(bp);
                return (error);
        }

        /* [set up the fixed part of the buffer for a transfer] */
        bp->b_dev = dev;
        bp->b_proc = p;

        buf_seterror(bp, 0);
        /*
         * [while there is data to transfer and no I/O error]
         * Note that I/O errors are handled with a 'goto' at the bottom
         * of the 'while' loop.
         */
        for (i = 0; i < uio->uio_iovcnt; i++) {
                while (uio_iov_len_at(uio, i) > 0) {
                        /*
                         * [mark the buffer busy for physical I/O]
                         * (i.e. set B_PHYS (because it's an I/O to user
                         * memory, and B_RAW, because B_RAW is to be
                         * "Set by physio for raw transfers.", in addition
                         * to the read/write flag.)
                         */
                        buf_setflags(bp, B_PHYS | B_RAW | flags);
                        
                        if ( (iosize = uio_iov_len_at(uio, i)) > MAXPHYSIO_WIRED)
                                iosize = MAXPHYSIO_WIRED;

                        /* [set up the buffer for a maximum-sized transfer] */
                        buf_setblkno(bp, uio->uio_offset / blocksize);
                        buf_setcount(bp, iosize);
                        // LP64todo - fix this!
                        buf_setdataptr(bp, CAST_DOWN(caddr_t, uio_iov_base_at(uio, i)));
                        
                        /*
                         * [call minphys to bound the tranfer size]
                         * and remember the amount of data to transfer,
                         * for later comparison.
                         */
                        (*minphys)(bp);
                        todo = buf_count(bp);

                        /*
                         * [lock the part of the user address space involved
                         *    in the transfer]
                         */

                        if(UIO_SEG_IS_USER_SPACE(uio->uio_segflg))
                                vslock(CAST_USER_ADDR_T(buf_dataptr(bp)),
                                       (user_size_t)todo);
                        
                        /* [call strategy to start the transfer] */
                        (*strategy)(bp);


                        /* [wait for the transfer to complete] */
                        error = (int)buf_biowait(bp);

                        /*
                         * [unlock the part of the address space previously
                         *    locked]
                         */
                        if(UIO_SEG_IS_USER_SPACE(uio->uio_segflg))
                                vsunlock(CAST_USER_ADDR_T(buf_dataptr(bp)),
                                         (user_size_t)todo,
                                         (flags & B_READ));

                        /*
                         * [deduct the transfer size from the total number
                         *    of data to transfer]
                         */
                        done = buf_count(bp) - buf_resid(bp);
                        uio_iov_len_add_at(uio, -done, i);
                        uio_iov_base_add_at(uio, done, i);
                        uio->uio_offset += done;
                        uio_setresid(uio, (uio_resid(uio) - done));

                        /*
                         * Now, check for an error.
                         * Also, handle weird end-of-disk semantics.
                         */
                        if (error || done < todo)
                                goto done;
                }
        }

done:
        /*
         * [clean up the state of the buffer]
         * Remember if somebody wants it, so we can wake them up below.
         * Also, if we had to steal it, give it back.
         */

        buf_clearflags(bp, B_PHYS | B_RAW);
        if (nobuf)
                buf_free(bp);
        else 
                {
                        buf_drop(bp);
                }

        return (error);
}

/*
 * Leffler, et al., says on p. 231:
 * "The minphys() routine is called by physio() to adjust the
 * size of each I/O transfer before the latter is passed to
 * the strategy routine..." 
 *
 * so, just adjust the buffer's count accounting to MAXPHYS here,
 * and return the new count;
 */
u_int
minphys(bp)
        struct buf *bp;
{

        buf_setcount(bp, min(MAXPHYS, buf_count(bp)));
        return buf_count(bp);
}

/*
 * Do a read on a device for a user process.
 */
rawread(dev, uio)
        dev_t dev;
        struct uio *uio;
{
        return (physio(cdevsw[major(dev)].d_strategy, (struct buf *)NULL,
            dev, B_READ, minphys, uio, DEV_BSIZE));
}

/*
 * Do a write on a device for a user process.
 */
rawwrite(dev, uio)
        dev_t dev;
        struct uio *uio;
{
        return (physio(cdevsw[major(dev)].d_strategy, (struct buf *)NULL,
            dev, B_WRITE, minphys, uio, DEV_BSIZE));
}