/*
 * interface to scsi devices via scsi(2) to sd(3),
 * which does not implement LUNs.
 */
#include "all.h"
#include "io.h"

enum {
	Ninquiry	= 255,
	Nsense		= 255,

	CMDtest		= 0x00,
	CMDreqsense	= 0x03,
	CMDread6	= 0x08,
	CMDwrite6	= 0x0A,
	CMDinquiry	= 0x12,
	CMDstart	= 0x1B,
	CMDread10	= 0x28,
	CMDwrite10	= 0x2A,
};

typedef struct {
	Target	target[NTarget];
} Ctlr;
static Ctlr scsictlr[MaxScsi];

extern int scsiverbose;

void
scsiinit(void)
{
	Ctlr *ctlr;
	int ctlrno, targetno;
	Target *tp;

	scsiverbose = 1;
	for(ctlrno = 0; ctlrno < MaxScsi; ctlrno++){
		ctlr = &scsictlr[ctlrno];
		memset(ctlr, 0, sizeof(Ctlr));
		for(targetno = 0; targetno < NTarget; targetno++){
			tp = &ctlr->target[targetno];

			qlock(tp);
			qunlock(tp);
			sprint(tp->id, "scsictlr#%d.%d", ctlrno, targetno);

			tp->ctlrno = ctlrno;
			tp->targetno = targetno;
			tp->inquiry = malloc(Ninquiry);
			tp->sense = malloc(Nsense);
		}
	}
}

static uchar lastcmd[16];
static int lastcmdsz;

static int
sense2stcode(uchar *sense)
{
	switch(sense[2] & 0x0F){
	case 6:						/* unit attention */
		/*
		 * 0x28 - not ready to ready transition,
		 *	  medium may have changed.
		 * 0x29 - power on, RESET or BUS DEVICE RESET occurred.
		 */
		if(sense[12] != 0x28 && sense[12] != 0x29)
			return STcheck;
		/*FALLTHROUGH*/
	case 0:						/* no sense */
	case 1:						/* recovered error */
		return STok;
	case 8:						/* blank data */
		return STblank;
	case 2:						/* not ready */
		if(sense[12] == 0x3A)			/* medium not present */
			return STcheck;
		/*FALLTHROUGH*/
	default:
		/*
		 * If unit is becoming ready, rather than not ready,
		 * then wait a little then poke it again; should this
		 * be here or in the caller?
		 */
		if((sense[12] == 0x04 && sense[13] == 0x01)) {
			// delay(500);
			// scsitest(tp, lun);
			fprint(2, "sense2stcode: unit becoming ready\n");
			return STcheck;			/* not exactly right */
		}
		return STcheck;
	}
}

/*
 * issue the SCSI command via scsi(2).  lun must already be in cmd[1].
 */
static int
doscsi(Target* tp, int rw, uchar* cmd, int cbytes, void* data, int* dbytes)
{
	int lun, db = 0;
	uchar reqcmd[6], reqdata[Nsense], dummy[1];
	Scsi *sc;

	sc = tp->sc;
	if (sc == nil)
		panic("doscsi: nil tp->sc");
	lun = cmd[1] >> 5;	/* save lun in case we need it for reqsense */

	/* cope with zero arguments */
	if (dbytes != nil)
		db = *dbytes;
	if (data == nil)
		data = dummy;

	if (scsi(sc, cmd, cbytes, data, db, rw) >= 0)
		return STok;

	/* cmd failed, get whatever sense data we can */
	memset(reqcmd, 0, sizeof reqcmd);
	reqcmd[0] = CMDreqsense;
	reqcmd[1] = lun<<5;
	reqcmd[4] = Nsense;
	memset(reqdata, 0, sizeof reqdata);
	if (scsicmd(sc, reqcmd, sizeof reqcmd, reqdata, sizeof reqdata,
	    Sread) < 0)
		return STharderr;

	/* translate sense data to ST* codes */
	return sense2stcode(reqdata);
}

static int
scsiexec(Target* tp, int rw, uchar* cmd, int cbytes, void* data, int* dbytes)
{
	int s;

	/*
	 * issue the SCSI command.  lun must already be in cmd[1].
	 */
	s = doscsi(tp, rw, cmd, cbytes, data, dbytes);
	switch(s){

	case STcheck:
		memmove(lastcmd, cmd, cbytes);
		lastcmdsz = cbytes;
		/*FALLTHROUGH*/

	default:
		/*
		 * It's more complicated than this.  There are conditions which
		 * are 'ok' but for which the returned status code is not 'STok'.
		 * Also, not all conditions require a reqsense, there may be a
		 * need to do a reqsense here when necessary and making it
		 * available to the caller somehow.
		 *
		 * Later.
		 */
		break;
	}

	return s;
}

static int
scsitest(Target* tp, char lun)
{
	uchar cmd[6];

	memset(cmd, 0, sizeof cmd);
	cmd[0] = CMDtest;
	cmd[1] = lun<<5;
	return scsiexec(tp, SCSIread, cmd, sizeof cmd, 0, 0);

}

static int
scsistart(Target* tp, char lun, int start)
{
	uchar cmd[6];

	memset(cmd, 0, sizeof cmd);
	cmd[0] = CMDstart;
	cmd[1] = lun<<5;
	if(start)
		cmd[4] = 1;
	return scsiexec(tp, SCSIread, cmd, sizeof cmd, 0, 0);
}

static int
scsiinquiry(Target* tp, char lun, int* nbytes)
{
	uchar cmd[6];

	memset(cmd, 0, sizeof cmd);
	cmd[0] = CMDinquiry;
	cmd[1] = lun<<5;
	*nbytes = Ninquiry;
	cmd[4] = *nbytes;
	return scsiexec(tp, SCSIread, cmd, sizeof cmd, tp->inquiry, nbytes);
}

static char *key[] =
{
	"no sense",
	"recovered error",
	"not ready",
	"medium error",
	"hardware error",
	"illegal request",
	"unit attention",
	"data protect",
	"blank check",
	"vendor specific",
	"copy aborted",
	"aborted command",
	"equal",
	"volume overflow",
	"miscompare",
	"reserved"
};

static int
scsireqsense(Target* tp, char lun, int* nbytes, int quiet)
{
	char *s;
	int n, status, try;
	uchar cmd[6], *sense;

	sense = tp->sense;
	for(try = 0; try < 20; try++) {
		memset(cmd, 0, sizeof cmd);
		cmd[0] = CMDreqsense;
		cmd[1] = lun<<5;
		cmd[4] = Ninquiry;
		memset(sense, 0, Ninquiry);

		*nbytes = Ninquiry;
		status = scsiexec(tp, SCSIread, cmd, sizeof cmd, sense, nbytes);
		if(status != STok)
			return status;
		*nbytes = sense[0x07]+8;

		switch(sense[2] & 0x0F){
		case 6:					/* unit attention */
			/*
			 * 0x28 - not ready to ready transition,
			 *	  medium may have changed.
			 * 0x29 - power on, RESET or BUS DEVICE RESET occurred.
			 */
			if(sense[12] != 0x28 && sense[12] != 0x29)
				goto buggery;
			/*FALLTHROUGH*/
		case 0:					/* no sense */
		case 1:					/* recovered error */
			return STok;
		case 8:					/* blank data */
			return STblank;
		case 2:					/* not ready */
			if(sense[12] == 0x3A)		/* medium not present */
				goto buggery;
			/*FALLTHROUGH*/
		default:
			/*
			 * If unit is becoming ready, rather than not ready,
			 * then wait a little then poke it again; should this
			 * be here or in the caller?
			 */
			if((sense[12] == 0x04 && sense[13] == 0x01)){
				delay(500);
				scsitest(tp, lun);
				break;
			}
			goto buggery;
		}
	}

buggery:
	if(quiet == 0){
		s = key[sense[2]&0x0F];
		print("%s: reqsense: '%s' code #%2.2ux #%2.2ux\n",
			tp->id, s, sense[12], sense[13]);
		print("%s: byte 2: #%2.2ux, bytes 15-17: #%2.2ux #%2.2ux #%2.2ux\n",
			tp->id, sense[2], sense[15], sense[16], sense[17]);
		print("lastcmd (%d): ", lastcmdsz);
		for(n = 0; n < lastcmdsz; n++)
			print(" #%2.2ux", lastcmd[n]);
		print("\n");
	}

	return STcheck;
}

static Target*
scsitarget(Device* d)
{
	int ctlrno, targetno;

	ctlrno = d->wren.ctrl;
	if(ctlrno < 0 || ctlrno >= MaxScsi /* || scsictlr[ctlrno].io == nil */)
		return 0;
	targetno = d->wren.targ;
	if(targetno < 0 || targetno >= NTarget)
		return 0;
	return &scsictlr[ctlrno].target[targetno];
}

static void
scsiprobe(Device* d)
{
	Target *tp;
	int nbytes, s;
	uchar *sense;
	int acount;

	if((tp = scsitarget(d)) == 0)
		panic("scsiprobe: device = %Z", d);

	acount = 0;
again:
	s = scsitest(tp, d->wren.lun);
	if(s < STok){
		print("%s: test, status %d\n", tp->id, s);
		return;
	}

	/*
	 * Determine if the drive exists and is not ready or
	 * is simply not responding.
	 * If the status is OK but the drive came back with a 'power on' or
	 * 'reset' status, try the test again to make sure the drive is really
	 * ready.
	 * If the drive is not ready and requires intervention, try to spin it
	 * up.
	 */
	s = scsireqsense(tp, d->wren.lun, &nbytes, acount);
	sense = tp->sense;
	switch(s){
	case STok:
		if ((sense[2] & 0x0F) == 0x06 &&
		    (sense[12] == 0x28 || sense[12] == 0x29))
			if(acount == 0){
				acount = 1;
				goto again;
			}
		break;
	case STcheck:
		if((sense[2] & 0x0F) == 0x02){
			if(sense[12] == 0x3A)
				break;
			if(sense[12] == 0x04 && sense[13] == 0x02){
				print("%s: starting...\n", tp->id);
				if(scsistart(tp, d->wren.lun, 1) == STok)
					break;
				s = scsireqsense(tp, d->wren.lun, &nbytes, 0);
			}
		}
		/*FALLTHROUGH*/
	default:
		print("%s: unavailable, status %d\n", tp->id, s);
		return;
	}

	/*
	 * Inquire to find out what the device is.
	 * Hardware drivers may need some of the info.
	 */
	s = scsiinquiry(tp, d->wren.lun, &nbytes);
	if(s != STok) {
		print("%s: inquiry failed, status %d\n", tp->id, s);
		return;
	}
	print("%s: %s\n", tp->id, (char*)tp->inquiry+8);
	tp->ok = 1;
}

int
scsiio(Device* d, int rw, uchar* cmd, int cbytes, void* data, int dbytes)
{
	Target *tp;
	int e, nbytes, s;

	if((tp = scsitarget(d)) == 0)
		panic("scsiio: device = %Z", d);

	qlock(tp);
	if(tp->ok == 0)
		scsiprobe(d);
	qunlock(tp);

	s = STinit;
	for(e = 0; e < 10; e++){
		for(;;){
			nbytes = dbytes;
			s = scsiexec(tp, rw, cmd, cbytes, data, &nbytes);
			if(s == STok)
				break;
			s = scsireqsense(tp, d->wren.lun, &nbytes, 0);
			if(s == STblank && rw == SCSIread) {
				memset(data, 0, dbytes);
				return STok;
			}
			if(s != STok)
				break;
		}
		if(s == STok)
			break;
	}
	if(e)
		print("%s: retry %d cmd #%x\n", tp->id, e, cmd[0]);
	return s;
}

void
newscsi(Device *d, Scsi *sc)
{
	Target *tp;

	if((tp = scsitarget(d)) == nil)
		panic("newscsi: device = %Z", d);
	tp->sc = sc;		/* connect Target to Scsi */
}