/*	$OpenBSD: vscsi.c,v 1.52 2020/06/27 17:28:58 krw Exp $ */

/*
 * Copyright (c) 2008 David Gwynne <dlg@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/device.h>
#include <sys/conf.h>
#include <sys/queue.h>
#include <sys/rwlock.h>
#include <sys/pool.h>
#include <sys/task.h>
#include <sys/ioctl.h>
#include <sys/poll.h>
#include <sys/selinfo.h>

#include <scsi/scsi_all.h>
#include <scsi/scsiconf.h>

#include <dev/vscsivar.h>

int		vscsi_match(struct device *, void *, void *);
void		vscsi_attach(struct device *, struct device *, void *);
void		vscsi_shutdown(void *);

struct vscsi_ccb {
	TAILQ_ENTRY(vscsi_ccb)	ccb_entry;
	int			ccb_tag;
	struct scsi_xfer	*ccb_xs;
	size_t			ccb_datalen;
};

TAILQ_HEAD(vscsi_ccb_list, vscsi_ccb);

enum vscsi_state {
	VSCSI_S_CLOSED,
	VSCSI_S_CONFIG,
	VSCSI_S_RUNNING
};

struct vscsi_softc {
	struct device		sc_dev;
	struct scsi_link	sc_link;
	struct scsibus_softc	*sc_scsibus;

	struct mutex		sc_state_mtx;
	enum vscsi_state	sc_state;
	u_int			sc_ref_count;
	struct pool		sc_ccb_pool;

	struct scsi_iopool	sc_iopool;

	struct vscsi_ccb_list	sc_ccb_i2t;
	struct vscsi_ccb_list	sc_ccb_t2i;
	int			sc_ccb_tag;
	struct mutex		sc_poll_mtx;
	struct rwlock		sc_ioc_lock;

	struct selinfo		sc_sel;
	struct mutex		sc_sel_mtx;
};

#define DEVNAME(_s) ((_s)->sc_dev.dv_xname)
#define DEV2SC(_d) ((struct vscsi_softc *)device_lookup(&vscsi_cd, minor(_d)))

struct cfattach vscsi_ca = {
	sizeof(struct vscsi_softc),
	vscsi_match,
	vscsi_attach
};

struct cfdriver vscsi_cd = {
	NULL,
	"vscsi",
	DV_DULL
};

void		vscsi_cmd(struct scsi_xfer *);
int		vscsi_probe(struct scsi_link *);
void		vscsi_free(struct scsi_link *);

struct scsi_adapter vscsi_switch = {
	vscsi_cmd, NULL, vscsi_probe, vscsi_free, NULL
};

int		vscsi_i2t(struct vscsi_softc *, struct vscsi_ioc_i2t *);
int		vscsi_data(struct vscsi_softc *, struct vscsi_ioc_data *, int);
int		vscsi_t2i(struct vscsi_softc *, struct vscsi_ioc_t2i *);
int		vscsi_devevent(struct vscsi_softc *, u_long,
		    struct vscsi_ioc_devevent *);
void		vscsi_devevent_task(void *);
void		vscsi_done(struct vscsi_softc *, struct vscsi_ccb *);

void *		vscsi_ccb_get(void *);
void		vscsi_ccb_put(void *, void *);

void		filt_vscsidetach(struct knote *);
int		filt_vscsiread(struct knote *, long);

const struct filterops vscsi_filtops = {
	.f_flags	= FILTEROP_ISFD,
	.f_attach	= NULL,
	.f_detach	= filt_vscsidetach,
	.f_event	= filt_vscsiread,
};


int
vscsi_match(struct device *parent, void *match, void *aux)
{
	return (1);
}

void
vscsi_attach(struct device *parent, struct device *self, void *aux)
{
	struct vscsi_softc		*sc = (struct vscsi_softc *)self;
	struct scsibus_attach_args	saa;

	printf("\n");

	mtx_init(&sc->sc_state_mtx, IPL_BIO);
	sc->sc_state = VSCSI_S_CLOSED;

	TAILQ_INIT(&sc->sc_ccb_i2t);
	TAILQ_INIT(&sc->sc_ccb_t2i);
	mtx_init(&sc->sc_poll_mtx, IPL_BIO);
	mtx_init(&sc->sc_sel_mtx, IPL_BIO);
	rw_init(&sc->sc_ioc_lock, "vscsiioc");
	scsi_iopool_init(&sc->sc_iopool, sc, vscsi_ccb_get, vscsi_ccb_put);

	sc->sc_link.adapter = &vscsi_switch;
	sc->sc_link.adapter_softc = sc;
	sc->sc_link.adapter_target = SDEV_NO_ADAPTER_TARGET;
	sc->sc_link.adapter_buswidth = 256;
	sc->sc_link.openings = 16;
	sc->sc_link.pool = &sc->sc_iopool;

	saa.saa_sc_link = &sc->sc_link;

	sc->sc_scsibus = (struct scsibus_softc *)config_found(&sc->sc_dev,
	    &saa, scsiprint);
}

void
vscsi_cmd(struct scsi_xfer *xs)
{
	struct scsi_link		*link = xs->sc_link;
	struct vscsi_softc		*sc = link->adapter_softc;
	struct vscsi_ccb		*ccb = xs->io;
	int				polled = ISSET(xs->flags, SCSI_POLL);
	int				running = 0;

	if (ISSET(xs->flags, SCSI_POLL) && ISSET(xs->flags, SCSI_NOSLEEP)) {
		printf("%s: POLL && NOSLEEP for 0x%02x\n", DEVNAME(sc),
		    xs->cmd->opcode);
		xs->error = XS_DRIVER_STUFFUP;
		scsi_done(xs);
		return;
	}

	ccb->ccb_xs = xs;

	mtx_enter(&sc->sc_state_mtx);
	if (sc->sc_state == VSCSI_S_RUNNING) {
		running = 1;
		TAILQ_INSERT_TAIL(&sc->sc_ccb_i2t, ccb, ccb_entry);
	}
	mtx_leave(&sc->sc_state_mtx);

	if (!running) {
		xs->error = XS_DRIVER_STUFFUP;
		scsi_done(xs);
		return;
	}

	selwakeup(&sc->sc_sel);

	if (polled) {
		mtx_enter(&sc->sc_poll_mtx);
		while (ccb->ccb_xs != NULL)
			msleep_nsec(ccb, &sc->sc_poll_mtx, PRIBIO, "vscsipoll",
			    INFSLP);
		mtx_leave(&sc->sc_poll_mtx);
		scsi_done(xs);
	}
}

void
vscsi_done(struct vscsi_softc *sc, struct vscsi_ccb *ccb)
{
	struct scsi_xfer		*xs = ccb->ccb_xs;

	if (ISSET(xs->flags, SCSI_POLL)) {
		mtx_enter(&sc->sc_poll_mtx);
		ccb->ccb_xs = NULL;
		wakeup(ccb);
		mtx_leave(&sc->sc_poll_mtx);
	} else
		scsi_done(xs);
}

int
vscsi_probe(struct scsi_link *link)
{
	struct vscsi_softc		*sc = link->adapter_softc;
	int				rv = 0;

	mtx_enter(&sc->sc_state_mtx);
	if (sc->sc_state == VSCSI_S_RUNNING)
		sc->sc_ref_count++;
	else
		rv = ENXIO;
	mtx_leave(&sc->sc_state_mtx);

	return (rv);
}

void
vscsi_free(struct scsi_link *link)
{
	struct vscsi_softc		*sc = link->adapter_softc;

	mtx_enter(&sc->sc_state_mtx);
	sc->sc_ref_count--;
	if (sc->sc_state != VSCSI_S_RUNNING && sc->sc_ref_count == 0)
		wakeup(&sc->sc_ref_count);
	mtx_leave(&sc->sc_state_mtx);
}

int
vscsiopen(dev_t dev, int flags, int mode, struct proc *p)
{
	struct vscsi_softc		*sc = DEV2SC(dev);
	enum vscsi_state		state = VSCSI_S_RUNNING;
	int				rv = 0;

	if (sc == NULL)
		return (ENXIO);

	mtx_enter(&sc->sc_state_mtx);
	if (sc->sc_state != VSCSI_S_CLOSED)
		rv = EBUSY;
	else
		sc->sc_state = VSCSI_S_CONFIG;
	mtx_leave(&sc->sc_state_mtx);

	if (rv != 0) {
		device_unref(&sc->sc_dev);
		return (rv);
	}

	pool_init(&sc->sc_ccb_pool, sizeof(struct vscsi_ccb), 0, IPL_BIO, 0,
	    "vscsiccb", NULL);

	/* we need to guarantee some ccbs will be available for the iopool */
	rv = pool_prime(&sc->sc_ccb_pool, 8);
	if (rv != 0) {
		pool_destroy(&sc->sc_ccb_pool);
		state = VSCSI_S_CLOSED;
	}

	/* commit changes */
	mtx_enter(&sc->sc_state_mtx);
	sc->sc_state = state;
	mtx_leave(&sc->sc_state_mtx);

	device_unref(&sc->sc_dev);
	return (rv);
}

int
vscsiioctl(dev_t dev, u_long cmd, caddr_t addr, int flags, struct proc *p)
{
	struct vscsi_softc		*sc = DEV2SC(dev);
	int				read = 0;
	int				err = 0;

	if (sc == NULL)
		return (ENXIO);

	rw_enter_write(&sc->sc_ioc_lock);

	switch (cmd) {
	case VSCSI_I2T:
		err = vscsi_i2t(sc, (struct vscsi_ioc_i2t *)addr);
		break;

	case VSCSI_DATA_READ:
		read = 1;
	case VSCSI_DATA_WRITE:
		err = vscsi_data(sc, (struct vscsi_ioc_data *)addr, read);
		break;

	case VSCSI_T2I:
		err = vscsi_t2i(sc, (struct vscsi_ioc_t2i *)addr);
		break;

	case VSCSI_REQPROBE:
	case VSCSI_REQDETACH:
		err = vscsi_devevent(sc, cmd,
		    (struct vscsi_ioc_devevent *)addr);
		break;

	default:
		err = ENOTTY;
		break;
	}

	rw_exit_write(&sc->sc_ioc_lock);

	device_unref(&sc->sc_dev);
	return (err);
}

int
vscsi_i2t(struct vscsi_softc *sc, struct vscsi_ioc_i2t *i2t)
{
	struct vscsi_ccb		*ccb;
	struct scsi_xfer		*xs;
	struct scsi_link		*link;

	mtx_enter(&sc->sc_state_mtx);
	ccb = TAILQ_FIRST(&sc->sc_ccb_i2t);
	if (ccb != NULL)
		TAILQ_REMOVE(&sc->sc_ccb_i2t, ccb, ccb_entry);
	mtx_leave(&sc->sc_state_mtx);

	if (ccb == NULL)
		return (EAGAIN);

	xs = ccb->ccb_xs;
	link = xs->sc_link;

	i2t->tag = ccb->ccb_tag;
	i2t->target = link->target;
	i2t->lun = link->lun;
	memcpy(&i2t->cmd, xs->cmd, xs->cmdlen);
	i2t->cmdlen = xs->cmdlen;
	i2t->datalen = xs->datalen;

	switch (xs->flags & (SCSI_DATA_IN | SCSI_DATA_OUT)) {
	case SCSI_DATA_IN:
		i2t->direction = VSCSI_DIR_READ;
		break;
	case SCSI_DATA_OUT:
		i2t->direction = VSCSI_DIR_WRITE;
		break;
	default:
		i2t->direction = VSCSI_DIR_NONE;
		break;
	}

	TAILQ_INSERT_TAIL(&sc->sc_ccb_t2i, ccb, ccb_entry);

	return (0);
}

int
vscsi_data(struct vscsi_softc *sc, struct vscsi_ioc_data *data, int read)
{
	struct vscsi_ccb		*ccb;
	struct scsi_xfer		*xs;
	int				xsread;
	u_int8_t			*buf;
	int				rv = EINVAL;

	TAILQ_FOREACH(ccb, &sc->sc_ccb_t2i, ccb_entry) {
		if (ccb->ccb_tag == data->tag)
			break;
	}
	if (ccb == NULL)
		return (EFAULT);

	xs = ccb->ccb_xs;

	if (data->datalen > xs->datalen - ccb->ccb_datalen)
		return (ENOMEM);

	switch (xs->flags & (SCSI_DATA_IN | SCSI_DATA_OUT)) {
	case SCSI_DATA_IN:
		xsread = 1;
		break;
	case SCSI_DATA_OUT:
		xsread = 0;
		break;
	default:
		return (EINVAL);
	}

	if (read != xsread)
		return (EINVAL);

	buf = xs->data;
	buf += ccb->ccb_datalen;

	if (read)
		rv = copyin(data->data, buf, data->datalen);
	else
		rv = copyout(buf, data->data, data->datalen);

	if (rv == 0)
		ccb->ccb_datalen += data->datalen;

	return (rv);
}

int
vscsi_t2i(struct vscsi_softc *sc, struct vscsi_ioc_t2i *t2i)
{
	struct vscsi_ccb		*ccb;
	struct scsi_xfer		*xs;
	int				rv = 0;

	TAILQ_FOREACH(ccb, &sc->sc_ccb_t2i, ccb_entry) {
		if (ccb->ccb_tag == t2i->tag)
			break;
	}
	if (ccb == NULL)
		return (EFAULT);

	TAILQ_REMOVE(&sc->sc_ccb_t2i, ccb, ccb_entry);

	xs = ccb->ccb_xs;

	xs->resid = xs->datalen - ccb->ccb_datalen;
	xs->status = SCSI_OK;

	switch (t2i->status) {
	case VSCSI_STAT_DONE:
		xs->error = XS_NOERROR;
		break;
	case VSCSI_STAT_SENSE:
		xs->error = XS_SENSE;
		memcpy(&xs->sense, &t2i->sense, sizeof(xs->sense));
		break;
	case VSCSI_STAT_RESET:
		xs->error = XS_RESET;
		break;
	case VSCSI_STAT_ERR:
	default:
		xs->error = XS_DRIVER_STUFFUP;
		break;
	}

	vscsi_done(sc, ccb);

	return (rv);
}

struct vscsi_devevent_task {
	struct vscsi_softc *sc;
	struct task t;
	struct vscsi_ioc_devevent de;
	u_long cmd;
};

int
vscsi_devevent(struct vscsi_softc *sc, u_long cmd,
    struct vscsi_ioc_devevent *de)
{
	struct vscsi_devevent_task *dt;

	dt = malloc(sizeof(*dt), M_TEMP, M_WAITOK | M_CANFAIL);
	if (dt == NULL)
		return (ENOMEM);

	task_set(&dt->t, vscsi_devevent_task, dt);
	dt->sc = sc;
	dt->de = *de;
	dt->cmd = cmd;

	device_ref(&sc->sc_dev);
	task_add(systq, &dt->t);

	return (0);
}

void
vscsi_devevent_task(void *xdt)
{
	struct vscsi_devevent_task *dt = xdt;
	struct vscsi_softc *sc = dt->sc;
	int state;

	mtx_enter(&sc->sc_state_mtx);
	state = sc->sc_state;
	mtx_leave(&sc->sc_state_mtx);

	if (state != VSCSI_S_RUNNING)
		goto gone;

	switch (dt->cmd) {
	case VSCSI_REQPROBE:
		scsi_probe(sc->sc_scsibus, dt->de.target, dt->de.lun);
		break;
	case VSCSI_REQDETACH:
		scsi_detach(sc->sc_scsibus, dt->de.target, dt->de.lun,
		    DETACH_FORCE);
		break;
#ifdef DIAGNOSTIC
	default:
		panic("unexpected vscsi_devevent cmd");
		/* NOTREACHED */
#endif
	}

gone:
	device_unref(&sc->sc_dev);

	free(dt, M_TEMP, sizeof(*dt));
}

int
vscsipoll(dev_t dev, int events, struct proc *p)
{
	struct vscsi_softc		*sc = DEV2SC(dev);
	int				revents = 0;

	if (sc == NULL)
		return (POLLERR);

	if (events & (POLLIN | POLLRDNORM)) {
		mtx_enter(&sc->sc_state_mtx);
		if (!TAILQ_EMPTY(&sc->sc_ccb_i2t))
			revents |= events & (POLLIN | POLLRDNORM);
		mtx_leave(&sc->sc_state_mtx);
	}

	if (revents == 0) {
		if (events & (POLLIN | POLLRDNORM))
			selrecord(p, &sc->sc_sel);
	}

	device_unref(&sc->sc_dev);
	return (revents);
}

int
vscsikqfilter(dev_t dev, struct knote *kn)
{
	struct vscsi_softc *sc = DEV2SC(dev);
	struct klist *klist;

	if (sc == NULL)
		return (ENXIO);

	klist = &sc->sc_sel.si_note;

	switch (kn->kn_filter) {
	case EVFILT_READ:
		kn->kn_fop = &vscsi_filtops;
		break;
	default:
		device_unref(&sc->sc_dev);
		return (EINVAL);
	}

	kn->kn_hook = sc;

	mtx_enter(&sc->sc_sel_mtx);
	klist_insert(klist, kn);
	mtx_leave(&sc->sc_sel_mtx);

	/* device ref is given to the knote in the klist */

	return (0);
}

void
filt_vscsidetach(struct knote *kn)
{
	struct vscsi_softc *sc = kn->kn_hook;
	struct klist *klist = &sc->sc_sel.si_note;

	mtx_enter(&sc->sc_sel_mtx);
	klist_remove(klist, kn);
	mtx_leave(&sc->sc_sel_mtx);

	device_unref(&sc->sc_dev);
}

int
filt_vscsiread(struct knote *kn, long hint)
{
	struct vscsi_softc *sc = kn->kn_hook;
	int event = 0;

	mtx_enter(&sc->sc_state_mtx);
	if (!TAILQ_EMPTY(&sc->sc_ccb_i2t))
		event = 1;
	mtx_leave(&sc->sc_state_mtx);

	return (event);
}

int
vscsiclose(dev_t dev, int flags, int mode, struct proc *p)
{
	struct vscsi_softc		*sc = DEV2SC(dev);
	struct vscsi_ccb		*ccb;

	if (sc == NULL)
		return (ENXIO);

	mtx_enter(&sc->sc_state_mtx);
	KASSERT(sc->sc_state == VSCSI_S_RUNNING);
	sc->sc_state = VSCSI_S_CONFIG;
	mtx_leave(&sc->sc_state_mtx);

	scsi_activate(sc->sc_scsibus, -1, -1, DVACT_DEACTIVATE);

	while ((ccb = TAILQ_FIRST(&sc->sc_ccb_t2i)) != NULL) {
		TAILQ_REMOVE(&sc->sc_ccb_t2i, ccb, ccb_entry);
		ccb->ccb_xs->error = XS_RESET;
		vscsi_done(sc, ccb);
	}

	while ((ccb = TAILQ_FIRST(&sc->sc_ccb_i2t)) != NULL) {
		TAILQ_REMOVE(&sc->sc_ccb_i2t, ccb, ccb_entry);
		ccb->ccb_xs->error = XS_RESET;
		vscsi_done(sc, ccb);
	}

	scsi_req_detach(sc->sc_scsibus, -1, -1, DETACH_FORCE);

	mtx_enter(&sc->sc_state_mtx);
	while (sc->sc_ref_count > 0) {
		msleep_nsec(&sc->sc_ref_count, &sc->sc_state_mtx,
		    PRIBIO, "vscsiref", INFSLP);
	}
	mtx_leave(&sc->sc_state_mtx);

	pool_destroy(&sc->sc_ccb_pool);

	mtx_enter(&sc->sc_state_mtx);
	sc->sc_state = VSCSI_S_CLOSED;
	mtx_leave(&sc->sc_state_mtx);

	device_unref(&sc->sc_dev);
	return (0);
}

void *
vscsi_ccb_get(void *cookie)
{
	struct vscsi_softc		*sc = cookie;
	struct vscsi_ccb		*ccb = NULL;

	ccb = pool_get(&sc->sc_ccb_pool, PR_NOWAIT);
	if (ccb != NULL) {
		ccb->ccb_tag = sc->sc_ccb_tag++;
		ccb->ccb_datalen = 0;
	}

	return (ccb);
}

void
vscsi_ccb_put(void *cookie, void *io)
{
	struct vscsi_softc		*sc = cookie;
	struct vscsi_ccb		*ccb = io;

	pool_put(&sc->sc_ccb_pool, ccb);
}