/*      $NetBSD: md.c,v 1.87 2023/01/13 15:46:40 hannken Exp $  */

/*
 * Copyright (c) 1995 Gordon W. Ross, Leo Weppelman.
 * 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.
 * 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 AUTHOR ``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 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.
 */

/*
 * This implements a general-purpose memory-disk.
 * See md.h for notes on the config types.
 *
 * Note that this driver provides the same functionality
 * as the MFS filesystem hack, but this is better because
 * you can use this for any filesystem type you'd like!
 *
 * Credit for most of the kmem ramdisk code goes to:
 *   Leo Weppelman (atari) and Phil Nelson (pc532)
 * Credit for the ideas behind the "user space memory" code goes
 * to the authors of the MFS implementation.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: md.c,v 1.87 2023/01/13 15:46:40 hannken Exp $");

#ifdef _KERNEL_OPT
#include "opt_md.h"
#else
#define MEMORY_DISK_SERVER 1
#endif

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/kmem.h>
#include <sys/systm.h>
#include <sys/buf.h>
#include <sys/bufq.h>
#include <sys/device.h>
#include <sys/disk.h>
#include <sys/stat.h>
#include <sys/proc.h>
#include <sys/conf.h>
#include <sys/disklabel.h>

#include <uvm/uvm_extern.h>

#include <dev/md.h>

#include "ioconf.h"
/*
 * The user-space functionality is included by default.
 * Use  `options MEMORY_DISK_SERVER=0' to turn it off.
 */
#ifndef MEMORY_DISK_SERVER
#error MEMORY_DISK_SERVER should be defined by opt_md.h
#endif  /* MEMORY_DISK_SERVER */

/*
 * We should use the raw partition for ioctl.
 */
#define MD_UNIT(unit)   DISKUNIT(unit)

/* autoconfig stuff... */

struct md_softc {
        device_t sc_dev;        /* Self. */
        struct disk sc_dkdev;   /* hook for generic disk handling */
        struct md_conf sc_md;
        kmutex_t sc_lock;       /* Protect self. */
        kcondvar_t sc_cv;       /* Wait here for work. */
        struct bufq_state *sc_buflist;
};
/* shorthand for fields in sc_md: */
#define sc_addr sc_md.md_addr
#define sc_size sc_md.md_size
#define sc_type sc_md.md_type

static void     md_attach(device_t, device_t, void *);
static int      md_detach(device_t, int);

static dev_type_open(mdopen);
static dev_type_close(mdclose);
static dev_type_read(mdread);
static dev_type_write(mdwrite);
static dev_type_ioctl(mdioctl);
static dev_type_strategy(mdstrategy);
static dev_type_size(mdsize);

const struct bdevsw md_bdevsw = {
        .d_open = mdopen,
        .d_close = mdclose,
        .d_strategy = mdstrategy,
        .d_ioctl = mdioctl,
        .d_dump = nodump,
        .d_psize = mdsize,
        .d_discard = nodiscard,
        .d_flag = D_DISK | D_MPSAFE
};

const struct cdevsw md_cdevsw = {
        .d_open = mdopen,
        .d_close = mdclose,
        .d_read = mdread,
        .d_write = mdwrite,
        .d_ioctl = mdioctl,
        .d_stop = nostop,
        .d_tty = notty,
        .d_poll = nopoll,
        .d_mmap = nommap,
        .d_kqfilter = nokqfilter,
        .d_discard = nodiscard,
        .d_flag = D_DISK | D_MPSAFE
};

static const struct dkdriver mddkdriver = {
        .d_strategy = mdstrategy,
        .d_minphys = minphys
};

CFATTACH_DECL3_NEW(md, sizeof(struct md_softc),
        0, md_attach, md_detach, NULL, NULL, NULL, DVF_DETACH_SHUTDOWN);

static kmutex_t md_device_lock;         /* Protect unit creation / deletion. */
extern size_t md_root_size;

static void md_set_disklabel(struct md_softc *);

/*
 * This is called if we are configured as a pseudo-device
 */
void
mdattach(int n)
{

        mutex_init(&md_device_lock, MUTEX_DEFAULT, IPL_NONE);
        if (config_cfattach_attach(md_cd.cd_name, &md_ca)) {
                aprint_error("%s: cfattach_attach failed\n", md_cd.cd_name);
                return;
        }
}

static void
md_attach(device_t parent, device_t self, void *aux)
{
        struct md_softc *sc = device_private(self);

        sc->sc_dev = self;
        sc->sc_type = MD_UNCONFIGURED;
        mutex_init(&sc->sc_lock, MUTEX_DEFAULT, IPL_NONE);
        cv_init(&sc->sc_cv, "mdidle");
        bufq_alloc(&sc->sc_buflist, "fcfs", 0);

        /* XXX - Could accept aux info here to set the config. */
#ifdef  MEMORY_DISK_HOOKS
        /*
         * This external function might setup a pre-loaded disk.
         * All it would need to do is setup the md_conf struct.
         * See sys/dev/md_root.c for an example.
         */
        md_attach_hook(device_unit(self), &sc->sc_md);
#endif

        /*
         * Initialize and attach the disk structure.
         */
        disk_init(&sc->sc_dkdev, device_xname(self), &mddkdriver);
        disk_attach(&sc->sc_dkdev);

        if (sc->sc_type != MD_UNCONFIGURED)
                md_set_disklabel(sc);

        if (!pmf_device_register(self, NULL, NULL))
                aprint_error_dev(self, "couldn't establish power handler\n");
}

static int
md_detach(device_t self, int flags)
{
        struct md_softc *sc = device_private(self);
        int rc;

        rc = 0;
        mutex_enter(&sc->sc_dkdev.dk_openlock);
        if (sc->sc_dkdev.dk_openmask == 0 && sc->sc_type == MD_UNCONFIGURED)
                ;       /* nothing to do */
        else if ((flags & DETACH_FORCE) == 0)
                rc = EBUSY;
        mutex_exit(&sc->sc_dkdev.dk_openlock);

        if (rc != 0)
                return rc;

        pmf_device_deregister(self);
        disk_detach(&sc->sc_dkdev);
        disk_destroy(&sc->sc_dkdev);
        bufq_free(sc->sc_buflist);
        mutex_destroy(&sc->sc_lock);
        cv_destroy(&sc->sc_cv);
        return 0;
}

/*
 * operational routines:
 * open, close, read, write, strategy,
 * ioctl, dump, size
 */

#if MEMORY_DISK_SERVER
static int      md_server_loop(struct md_softc *sc);
static int      md_ioctl_server(struct md_softc *sc, struct md_conf *umd,
                    struct lwp *l);
#endif  /* MEMORY_DISK_SERVER */
static int      md_ioctl_kalloc(struct md_softc *sc, struct md_conf *umd,
                    struct lwp *l);

static int
mdsize(dev_t dev)
{
        struct md_softc *sc;
        int res;

        sc = device_lookup_private(&md_cd, MD_UNIT(dev));
        if (sc == NULL)
                return 0;

        mutex_enter(&sc->sc_lock);
        if (sc->sc_type == MD_UNCONFIGURED)
                res = 0;
        else
                res = sc->sc_size >> DEV_BSHIFT;
        mutex_exit(&sc->sc_lock);

        return res;
}

static int
mdopen(dev_t dev, int flag, int fmt, struct lwp *l)
{
        int unit;
        int part = DISKPART(dev);
        int pmask = 1 << part;
        cfdata_t cf;
        struct md_softc *sc;
        struct disk *dk;
#ifdef  MEMORY_DISK_HOOKS
        bool configured;
#endif

        mutex_enter(&md_device_lock);
        unit = MD_UNIT(dev);
        sc = device_lookup_private(&md_cd, unit);
        if (sc == NULL) {
                if (part != RAW_PART) {
                        mutex_exit(&md_device_lock);
                        return ENXIO;
                }
                cf = kmem_zalloc(sizeof(*cf), KM_SLEEP);
                cf->cf_name = md_cd.cd_name;
                cf->cf_atname = md_cd.cd_name;
                cf->cf_unit = unit;
                cf->cf_fstate = FSTATE_STAR;
                sc = device_private(config_attach_pseudo(cf));
                if (sc == NULL) {
                        mutex_exit(&md_device_lock);
                        return ENOMEM;
                }
        }

        dk = &sc->sc_dkdev;

        /*
         * The raw partition is used for ioctl to configure.
         */
        if (part == RAW_PART)
                goto ok;

#ifdef  MEMORY_DISK_HOOKS
        /* Call the open hook to allow loading the device. */
        configured = (sc->sc_type != MD_UNCONFIGURED);
        md_open_hook(unit, &sc->sc_md);
        /* initialize disklabel if the device is configured in open hook */
        if (!configured && sc->sc_type != MD_UNCONFIGURED)
                md_set_disklabel(sc);
#endif

        /*
         * This is a normal, "slave" device, so
         * enforce initialized.
         */
        if (sc->sc_type == MD_UNCONFIGURED) {
                mutex_exit(&md_device_lock);
                return ENXIO;
        }

ok:
        /* XXX duplicates code in dk_open().  Call dk_open(), instead? */
        mutex_enter(&dk->dk_openlock);
        /* Mark our unit as open. */
        switch (fmt) {
        case S_IFCHR:
                dk->dk_copenmask |= pmask;
                break;
        case S_IFBLK:
                dk->dk_bopenmask |= pmask;
                break;
        }

        dk->dk_openmask = dk->dk_copenmask | dk->dk_bopenmask;

        mutex_exit(&dk->dk_openlock);
        mutex_exit(&md_device_lock);
        return 0;
}

static int
mdclose(dev_t dev, int flag, int fmt, struct lwp *l)
{
        int part = DISKPART(dev);
        int pmask = 1 << part;
        int error;
        cfdata_t cf;
        struct md_softc *sc;
        struct disk *dk;

        sc = device_lookup_private(&md_cd, MD_UNIT(dev));
        if (sc == NULL)
                return ENXIO;

        dk = &sc->sc_dkdev;

        mutex_enter(&dk->dk_openlock);

        switch (fmt) {
        case S_IFCHR:
                dk->dk_copenmask &= ~pmask;
                break;
        case S_IFBLK:
                dk->dk_bopenmask &= ~pmask;
                break;
        }
        dk->dk_openmask = dk->dk_copenmask | dk->dk_bopenmask;
        if (dk->dk_openmask != 0) {
                mutex_exit(&dk->dk_openlock);
                return 0;
        }

        mutex_exit(&dk->dk_openlock);

        mutex_enter(&md_device_lock);
        cf = device_cfdata(sc->sc_dev);
        error = config_detach(sc->sc_dev, DETACH_QUIET);
        if (! error)
                kmem_free(cf, sizeof(*cf));
        mutex_exit(&md_device_lock);
        return error;
}

static int
mdread(dev_t dev, struct uio *uio, int flags)
{
        struct md_softc *sc;

        sc = device_lookup_private(&md_cd, MD_UNIT(dev));

        if (sc == NULL || sc->sc_type == MD_UNCONFIGURED)
                return ENXIO;

        return (physio(mdstrategy, NULL, dev, B_READ, minphys, uio));
}

static int
mdwrite(dev_t dev, struct uio *uio, int flags)
{
        struct md_softc *sc;

        sc = device_lookup_private(&md_cd, MD_UNIT(dev));

        if (sc == NULL || sc->sc_type == MD_UNCONFIGURED)
                return ENXIO;

        return (physio(mdstrategy, NULL, dev, B_WRITE, minphys, uio));
}

/*
 * Handle I/O requests, either directly, or
 * by passing them to the server process.
 */
static void
mdstrategy(struct buf *bp)
{
        struct md_softc *sc;
        void *  addr;
        size_t off, xfer;
        bool is_read;

        sc = device_lookup_private(&md_cd, MD_UNIT(bp->b_dev));

        if (sc == NULL || sc->sc_type == MD_UNCONFIGURED) {
                bp->b_error = ENXIO;
                goto done;
        }

        mutex_enter(&sc->sc_lock);

        switch (sc->sc_type) {
#if MEMORY_DISK_SERVER
        case MD_UMEM_SERVER:
                /* Just add this job to the server's queue. */
                bufq_put(sc->sc_buflist, bp);
                cv_signal(&sc->sc_cv);
                mutex_exit(&sc->sc_lock);
                /* see md_server_loop() */
                /* no biodone in this case */
                return;
#endif  /* MEMORY_DISK_SERVER */

        case MD_KMEM_FIXED:
        case MD_KMEM_ALLOCATED:
                /* These are in kernel space.  Access directly. */
                is_read = ((bp->b_flags & B_READ) == B_READ);
                bp->b_resid = bp->b_bcount;
                off = (bp->b_blkno << DEV_BSHIFT);
                if (off >= sc->sc_size) {
                        if (is_read)
                                break;  /* EOF */
                        goto set_eio;
                }
                xfer = bp->b_resid;
                if (xfer > (sc->sc_size - off))
                        xfer = (sc->sc_size - off);
                addr = (char *)sc->sc_addr + off;
                disk_busy(&sc->sc_dkdev);
                if (is_read)
                        memcpy(bp->b_data, addr, xfer);
                else
                        memcpy(addr, bp->b_data, xfer);
                disk_unbusy(&sc->sc_dkdev, xfer, is_read);
                bp->b_resid -= xfer;
                break;

        default:
                bp->b_resid = bp->b_bcount;
        set_eio:
                bp->b_error = EIO;
                break;
        }
        mutex_exit(&sc->sc_lock);

 done:

        biodone(bp);
}

static int
mdioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l)
{
        struct md_softc *sc;
        struct md_conf *umd;
        int error;

        if ((sc = device_lookup_private(&md_cd, MD_UNIT(dev))) == NULL)
                return ENXIO;

        if (sc->sc_type != MD_UNCONFIGURED) {
                error = disk_ioctl(&sc->sc_dkdev, dev, cmd, data, flag, l); 
                if (error != EPASSTHROUGH) {
                        return error;
                }
        }

        /* If this is not the raw partition, punt! */
        if (DISKPART(dev) != RAW_PART) {
                return ENOTTY;
        }

        mutex_enter(&sc->sc_lock);
        umd = (struct md_conf *)data;
        error = EINVAL;
        switch (cmd) {
        case MD_GETCONF:
                *umd = sc->sc_md;
                error = 0;
                break;

        case MD_SETCONF:
                /* Can only set it once. */
                if (sc->sc_type != MD_UNCONFIGURED)
                        break;
                switch (umd->md_type) {
                case MD_KMEM_ALLOCATED:
                        error = md_ioctl_kalloc(sc, umd, l);
                        break;
#if MEMORY_DISK_SERVER
                case MD_UMEM_SERVER:
                        error = md_ioctl_server(sc, umd, l);
                        break;
#endif  /* MEMORY_DISK_SERVER */
                default:
                        break;
                }
                break;
        }
        mutex_exit(&sc->sc_lock);
        return error;
}

static void
md_set_disklabel(struct md_softc *sc)
{
        struct disk_geom *dg = &sc->sc_dkdev.dk_geom;
        struct disklabel *lp = sc->sc_dkdev.dk_label;
        struct partition *pp;

        memset(lp, 0, sizeof(*lp));

        lp->d_secsize = DEV_BSIZE;
        lp->d_secperunit = sc->sc_size / DEV_BSIZE;
        if (lp->d_secperunit >= (32*64)) {
                lp->d_nsectors = 32;
                lp->d_ntracks = 64;
                lp->d_ncylinders = lp->d_secperunit / (32*64);
        } else {
                lp->d_nsectors = 1;
                lp->d_ntracks = 1;
                lp->d_ncylinders = lp->d_secperunit;
        }
        lp->d_secpercyl = lp->d_ntracks*lp->d_nsectors;

        strncpy(lp->d_typename, md_cd.cd_name, sizeof(lp->d_typename));
        lp->d_type = DKTYPE_MD;
        strncpy(lp->d_packname, "fictitious", sizeof(lp->d_packname));
        lp->d_rpm = 3600;
        lp->d_interleave = 1;
        lp->d_flags = 0;

        pp = &lp->d_partitions[0];
        pp->p_offset = 0;
        pp->p_size = lp->d_secperunit;
        pp->p_fstype = FS_BSDFFS;

        pp = &lp->d_partitions[RAW_PART];
        pp->p_offset = 0;
        pp->p_size = lp->d_secperunit;
        pp->p_fstype = FS_UNUSED;

        lp->d_npartitions = RAW_PART+1;
        lp->d_magic = DISKMAGIC;
        lp->d_magic2 = DISKMAGIC;
        lp->d_checksum = dkcksum(lp);

        memset(dg, 0, sizeof(*dg));

        dg->dg_secsize = lp->d_secsize;
        dg->dg_secperunit = lp->d_secperunit;
        dg->dg_nsectors = lp->d_nsectors;
        dg->dg_ntracks = lp->d_ntracks = 64;
        dg->dg_ncylinders = lp->d_ncylinders;

        disk_set_info(sc->sc_dev, &sc->sc_dkdev, NULL);
}

/*
 * Handle ioctl MD_SETCONF for (sc_type == MD_KMEM_ALLOCATED)
 * Just allocate some kernel memory and return.
 */
static int
md_ioctl_kalloc(struct md_softc *sc, struct md_conf *umd,
    struct lwp *l)
{
        vaddr_t addr;
        vsize_t size;

        /* Sanity check the size. */
        size = umd->md_size;
        if (size < DEV_BSIZE || (size % DEV_BSIZE) != 0)
                return EINVAL;

        mutex_exit(&sc->sc_lock);

        addr = uvm_km_alloc(kernel_map, size, 0, UVM_KMF_WIRED|UVM_KMF_ZERO);

        mutex_enter(&sc->sc_lock);

        if (!addr)
                return ENOMEM;

        /* If another thread beat us to configure this unit:  fail. */
        if (sc->sc_type != MD_UNCONFIGURED) {
                uvm_km_free(kernel_map, addr, size, UVM_KMF_WIRED);
                return EINVAL;
        }

        /* This unit is now configured. */
        sc->sc_addr = (void *)addr;     /* kernel space */
        sc->sc_size = (size_t)size;
        sc->sc_type = MD_KMEM_ALLOCATED;
        md_set_disklabel(sc);
        return 0;
}

#if MEMORY_DISK_SERVER

/*
 * Handle ioctl MD_SETCONF for (sc_type == MD_UMEM_SERVER)
 * Set config, then become the I/O server for this unit.
 */
static int
md_ioctl_server(struct md_softc *sc, struct md_conf *umd,
    struct lwp *l)
{
        vaddr_t end;
        int error;

        KASSERT(mutex_owned(&sc->sc_lock));

        /* Sanity check addr, size. */
        end = (vaddr_t) ((char *)umd->md_addr + umd->md_size);

        if (
#ifndef _RUMPKERNEL
            /*
             * On some architectures (e.g. powerpc) rump kernel provides
             * "safe" low defaults which make this test fail since malloc
             * does return higher addresses than the "safe" default.
             */
            (end >= VM_MAXUSER_ADDRESS) ||
#endif
            (end < ((vaddr_t) umd->md_addr)))
                return EINVAL;

        /* This unit is now configured. */
        sc->sc_addr = umd->md_addr;     /* user space */
        sc->sc_size = umd->md_size;
        sc->sc_type = MD_UMEM_SERVER;
        md_set_disklabel(sc);

        /* Become the server daemon */
        error = md_server_loop(sc);

        /* This server is now going away! */
        sc->sc_type = MD_UNCONFIGURED;
        sc->sc_addr = 0;
        sc->sc_size = 0;

        return (error);
}

static int
md_server_loop(struct md_softc *sc)
{
        struct buf *bp;
        void *addr;     /* user space address */
        size_t off;     /* offset into "device" */
        size_t xfer;    /* amount to transfer */
        int error;
        bool is_read;

        KASSERT(mutex_owned(&sc->sc_lock));

        for (;;) {
                /* Wait for some work to arrive. */
                while ((bp = bufq_get(sc->sc_buflist)) == NULL) {
                        error = cv_wait_sig(&sc->sc_cv, &sc->sc_lock);
                        if (error)
                                return error;
                }

                /* Do the transfer to/from user space. */
                mutex_exit(&sc->sc_lock);
                error = 0;
                is_read = ((bp->b_flags & B_READ) == B_READ);
                bp->b_resid = bp->b_bcount;
                off = (bp->b_blkno << DEV_BSHIFT);
                if (off >= sc->sc_size) {
                        if (is_read)
                                goto done;      /* EOF (not an error) */
                        error = EIO;
                        goto done;
                }
                xfer = bp->b_resid;
                if (xfer > (sc->sc_size - off))
                        xfer = (sc->sc_size - off);
                addr = (char *)sc->sc_addr + off;
                disk_busy(&sc->sc_dkdev);
                if (is_read)
                        error = copyin(addr, bp->b_data, xfer);
                else
                        error = copyout(bp->b_data, addr, xfer);
                disk_unbusy(&sc->sc_dkdev, (error ? 0 : xfer), is_read);
                if (!error)
                        bp->b_resid -= xfer;

        done:
                if (error) {
                        bp->b_error = error;
                }
                biodone(bp);
                mutex_enter(&sc->sc_lock);
        }
}
#endif  /* MEMORY_DISK_SERVER */