diff -Nru /sys/src/libfis/fis.c /sys/src/libfis/fis.c
--- /sys/src/libfis/fis.c	Thu Jan  1 00:00:00 1970
+++ /sys/src/libfis/fis.c	Fri Jan 17 00:00:00 2014
@@ -0,0 +1,555 @@
+/*
+ * sata fises and sas frames
+ * copyright © 2009-2010 erik quanstrom
+ */
+#include <u.h>
+#include <libc.h>
+#include <fis.h>
+
+static char *flagname[9] = {
+	"lba",
+	"llba",
+	"smart",
+	"power",
+	"nop",
+	"atapi",
+	"atapi16",
+	"ata8",
+	"sct",
+};
+
+/*
+ * ata8 standard (llba) cmd layout
+ *
+ * feature	16 bits
+ * count		16 bits
+ * lba		48 bits
+ * device		8 bits
+ * command	8 bits
+ *
+ * response:
+ *
+ * status		8 bits
+ * error		8 bits
+ * reason		8 bits
+ * count		8 bits
+ * sstatus		8 bits
+ * sactive		8 bits
+*/
+
+/*
+ * sata fis layout for fistype 0x27: host-to-device:
+ *
+ * 0	fistype
+ * 1	fis flags
+ * 2	ata command
+ * 3	features
+ * 4	sector	lba low	7:0
+ * 5	cyl low	lba mid	15:8
+ * 6	cyl hi	lba hi	23:16
+ * 7	device / head
+ * 8	sec exp	lba	31:24
+ * 9	cy low e	lba	39:32
+ * 10	cy hi e	lba	48:40
+ * 11	features (exp)
+ * 12	sector count
+ * 13	sector count (exp)
+ * 14	r
+ * 15	control
+ */
+
+void
+setfissig(Sfis *x, uint sig)
+{
+	x->sig = sig;
+}
+
+void
+skelfis(uchar *c)
+{
+	memset(c, 0, Fissize);
+	c[Ftype] = H2dev;
+	c[Fflags] = Fiscmd;
+	c[Fdev] = Ataobs;
+}
+
+int
+nopfis(Sfis*, uchar *c, int srst)
+{
+	skelfis(c);
+	if(srst){
+		c[Fflags] &= ~Fiscmd;
+		c[Fcontrol] = 1<<2;
+		return Preset|P28;
+	}
+	return Pnd|P28;
+}
+
+int
+txmodefis(Sfis *f, uchar *c, uchar d)
+{
+	int m;
+
+	/* hack */
+	if((f->sig >> 16) == 0xeb14)
+		return -1;
+	m = 0x40;
+	if(d == 0xff){
+		d = 0;
+		m = 0;
+	}
+	skelfis(c);
+	c[Fcmd] = 0xef;
+	c[Ffeat] = 3;			/* set transfer mode */
+	c[Fsc] = m | d;			/* sector count */
+	return Pnd|P28;
+}
+
+int
+featfis(Sfis*, uchar *c, uchar f)
+{
+	skelfis(c);
+	c[Fcmd] = 0xef;
+	c[Ffeat] = f;
+	return Pnd|P28;
+}
+
+int
+identifyfis(Sfis *f, uchar *c)
+{
+	static uchar tab[] = { 0xec, 0xa1, };
+
+	skelfis(c);
+	c[Fcmd] = tab[f->sig>>16 == 0xeb14];
+	return Pin|Ppio|P28|P512;
+}
+
+int
+flushcachefis(Sfis *f, uchar *c)
+{
+	static uchar tab[2] = {0xe7, 0xea};
+	static uchar ptab[2] = {Pnd|P28, Pnd|P48};
+	int llba;
+
+	llba = (f->feat & Dllba) != 0;
+	skelfis(c);
+	c[Fcmd] = tab[llba];
+	return ptab[llba];
+}
+
+static ushort
+gbit16(void *a)
+{
+	ushort j;
+	uchar *i;
+
+	i = a;
+	j  = i[1] << 8;
+	j |= i[0];
+	return j;
+}
+
+static uint
+gbit32(void *a)
+{
+	uint j;
+	uchar *i;
+
+	i = a;
+	j  = i[3] << 24;
+	j |= i[2] << 16;
+	j |= i[1] << 8;
+	j |= i[0];
+	return j;
+}
+
+static uvlong
+gbit64(void *a)
+{
+	uchar *i;
+
+	i = a;
+	return (uvlong)gbit32(i+4) << 32 | gbit32(a);
+}
+
+ushort
+id16(ushort *id, int i)
+{
+	return gbit16(id+i);
+}
+
+uint
+id32(ushort *id, int i)
+{
+	return gbit32(id+i);
+}
+
+uvlong
+id64(ushort *id, int i)
+{
+	return gbit64(id+i);
+}
+
+/* acs-2 §7.18.7.4 */
+static ushort puistab[] = {
+	0x37c8,	Pspinup,
+	0x738c,	Pspinup | Pidready,
+	0x8c73,	0,
+	0xc837,	Pidready,
+};
+
+int
+idpuis(ushort *id)
+{
+	ushort u, i;
+
+	u = gbit16(id + 2);
+	for(i = 0; i < nelem(puistab); i += 2)
+		if(u == puistab[i])
+			return puistab[i + 1];
+	return Pidready;	/* annoying cdroms */
+}
+
+static ushort
+onesc(ushort *id)
+{
+	ushort u;
+
+	u = gbit16(id);
+	if(u == 0xffff)
+		u = 0;
+	return u;
+}
+
+enum{
+	Idmasp	= 1<<8,
+	Ilbasp	= 1<<9,
+	Illba	= 1<<10,
+
+	Usepsec	= 1,
+};
+
+vlong
+idfeat(Sfis *f, ushort *id)
+{
+	int i, j;
+	vlong s;
+
+	f->feat = 0;
+	if(f->sig>>16 == 0xeb14)
+		f->feat |= Datapi;
+	i = gbit16(id + 49);
+	if((i & Ilbasp) == 0){
+		if(gbit16(id + 53) & 1){
+			f->c = gbit16(id + 1);
+			f->h = gbit16(id + 3);
+			f->s = gbit16(id + 6);
+		}else{
+			f->c = gbit16(id + 54);
+			f->h = gbit16(id + 55);
+			f->s = gbit16(id + 56);
+		}
+		s = f->c*f->h*f->s;
+	}else{
+		f->c = f->h = f->s = 0;
+		f->feat |= Dlba;
+		j = gbit16(id + 83) | gbit16(id + 86);
+		if(j & Illba){
+			f->feat |= Dllba;
+			s = gbit64(id + 100);
+		}else
+			s = gbit32(id + 60);
+	}
+	f->udma = 0xff;
+	if(i & Idmasp)
+	if(gbit16(id + 53) & 4)
+		for(i = gbit16(id + 88) & 0x7f; i; i >>= 1)
+			f->udma++;
+
+	if(f->feat & Datapi){
+		i = gbit16(id + 0);
+		if(i & 1)
+			f->feat |= Datapi16;
+	}
+
+	i = gbit16(id+83);
+	if((i>>14) == 1){
+		if(i & (1<<3))
+			f->feat |= Dpower;
+		i = gbit16(id + 82);
+		if(i & 1)
+			f->feat |= Dsmart;
+		if(i & (1<<14))
+			f->feat |= Dnop;
+	}
+	i = onesc(id + 80);
+	if(i & 1<<8){
+		f->feat |= Data8;
+		i = onesc(id + 222);			/* sata? */
+		j = onesc(id + 76);
+		if(i != 0 && i >> 12 == 1 && j != 0){
+			j >>= 1;
+			f->speeds = j & 7;
+			i = gbit16(id + 78) & gbit16(id + 79);
+			/*
+			 * not acceptable for comreset to
+			 * wipe out device configuration.
+			 * reject drive.
+			 */
+			if((i & 1<<6) == 0)
+				return -1;
+		}
+	}
+	if(gbit16(id + 206) & 1)
+		f->feat |= Dsct;
+	idss(f, id);
+	if(Usepsec)
+		return s>>f->physshift;
+	return s;
+}
+
+int
+idss(Sfis *f, ushort *id)
+{
+	uint sw, i;
+
+	if(f->sig>>16 == 0xeb14)
+		return 0;
+	f->lsectsz = 512;
+	f->physshift = 0;
+	i = gbit16(id + 106);
+	if(i >> 14 != 1)
+		return f->lsectsz;
+	if((sw = gbit32(id + 117)) >= 256)
+		f->lsectsz = sw * 2;
+	if(i & 1<<13)
+		f->physshift = i & 7;
+	if(Usepsec)
+		return f->lsectsz << f->physshift;
+	return f->lsectsz;
+}
+
+uvlong
+idwwn(Sfis*, ushort *id)
+{
+	uvlong u;
+
+	u = 0;
+	if(id[108]>>12 == 5){
+		u |= (uvlong)gbit16(id + 108) << 48;
+		u |= (uvlong)gbit16(id + 109) << 32;
+		u |= gbit16(id + 110) << 16;
+		u |= gbit16(id + 111) << 0;
+	}
+	return u;
+}
+
+void
+idmove(char *p, ushort *u, int n)
+{
+	int i;
+	char *op, *e, *s;
+
+	op = p;
+	s = (char*)u;
+	for(i = 0; i < n; i += 2){
+		*p++ = s[i + 1];
+		*p++ = s[i + 0];
+	}
+	*p = 0;
+	while(p > op && *--p == ' ')
+		*p = 0;
+	e = p;
+	p = op;
+	while(*p == ' ')
+		p++;
+	memmove(op, p, n - (e - p));
+}
+
+char*
+pflag(char *s, char *e, Sfis *f)
+{
+	ushort i, u;
+
+	u = f->feat;
+	for(i = 0; i < Dnflag; i++)
+		if(u & (1 << i))
+			s = seprint(s, e, "%s ", flagname[i]);
+	return seprint(s, e, "\n");
+}
+
+int
+atapirwfis(Sfis *f, uchar *c, uchar *cdb, int cdblen, int ndata)
+{
+	int fill, len;
+
+	fill = f->feat&Datapi16? 16: 12;
+	if((len = cdblen) > fill)
+		len = fill;
+	memmove(c + 0x40, cdb, len);
+	memset(c + 0x40 + len, 0, fill - len);
+
+	c[Ftype] = H2dev;
+	c[Fflags] = Fiscmd;
+	c[Fcmd] = Ataobs;
+	if(ndata != 0)
+		c[Ffeat] = 1;	/* dma */
+	else
+		c[Ffeat] = 0;	/* features (exp); */
+	c[Flba0] = 0;	
+	c[Flba8] = ndata;
+	c[Flba16] = ndata >> 8;
+	c[Fdev] = Ataobs;
+	memset(c + 8, 0, Fissize - 8);
+	return P28|Ppkt;
+}
+
+int
+rwfis(Sfis *f, uchar *c, int rw, int nsect, uvlong lba)
+{
+	uchar acmd, llba, udma;
+	static uchar tab[2][2][2] = { 0x20, 0x24, 0x30, 0x34, 0xc8, 0x25, 0xca, 0x35, };
+	static uchar ptab[2][2][2] = {
+		Pin|Ppio|P28,	Pin|Ppio|P48,
+		Pout|Ppio|P28,	Pout|Ppio|P48,
+		Pin|Pdma|P28,	Pin|Pdma|P48,
+		Pout|Pdma|P28,	Pout|Pdma|P48,
+	};
+
+	if(Usepsec){
+		nsect <<= f->physshift;
+		lba <<= f->physshift;
+	}
+
+	udma = f->udma != 0xff;
+	llba = (f->feat & Dllba) != 0;
+	acmd = tab[udma][rw][llba];
+
+	c[Ftype] = 0x27;
+	c[Fflags] = 0x80;
+	c[Fcmd] = acmd;
+	c[Ffeat] = 0;
+
+	c[Flba0] = lba;
+	c[Flba8] = lba >> 8;
+	c[Flba16] = lba >> 16;
+	c[Fdev] = Ataobs | Atalba;
+	if(llba == 0)
+		c[Fdev] |= (lba>>24) & 0xf;
+
+	c[Flba24] = lba >> 24;
+	c[Flba32] = lba >> 32;
+	c[Flba40] = lba >> 40;
+	c[Ffeat8] = 0;
+
+	c[Fsc] = nsect;
+	c[Fsc8] = nsect >> 8;
+	c[Ficc] = 0;
+	c[Fcontrol] = 0;
+
+	memset(c + 16, 0, Fissize - 16);
+	return ptab[udma][rw][llba];
+}
+
+uvlong
+fisrw(Sfis *f, uchar *c, int *n)
+{
+	uvlong lba;
+
+	lba = c[Flba0];
+	lba |= c[Flba8] << 8;
+	lba |= c[Flba16] << 16;
+	lba |= c[Flba24] << 24;
+	lba |= (uvlong)(c[Flba32] | c[Flba40]<<8) << 32;
+
+	*n = c[Fsc];
+	*n |= c[Fsc8] << 8;
+
+	if(Usepsec){
+		*n >>= f->physshift;
+		lba >>= f->physshift;
+	}
+
+	return lba;
+}
+
+void
+sigtofis(Sfis *f, uchar *c)
+{
+	uint u;
+
+	u = f->sig;
+	memset(c, 0, Fissize);
+	c[Ftype] = 0x34;
+	c[Fflags] = 0x00;
+	c[Fcmd] = 0x50;
+	c[Ffeat] = 0x01;
+	c[Flba0] = u >> 8;
+	c[Flba8] = u >> 16;
+	c[Flba16] = u >> 24;
+	c[Fdev] = Ataobs;
+	c[Fsc] = u;
+}
+
+uint
+fistosig(uchar *u)
+{
+	return u[Fsc] | u[Flba0]<<8 | u[Flba8]<<16 | u[Flba16]<<24;
+}
+
+
+/* sas smp */
+void
+smpskelframe(Cfis *f, uchar *c, int m)
+{
+	memset(c, 0, Fissize);
+	c[Ftype] = 0x40;
+	c[Fflags] = m;
+	if(f->phyid)
+		c[Flba32] = f->phyid;
+}
+
+uint
+sashash(uvlong u)
+{
+	uint poly, msb, l, r;
+	uvlong m;
+
+	r = 0;
+	poly = 0x01db2777;
+	msb = 0x01000000;
+	for(m = 1ull<<63; m > 0; m >>= 1){
+		l = 0;
+		if(m & u)
+			l = msb;
+		r <<= 1;
+		r ^= l;
+		if(r & msb)
+			r ^= poly;
+	}
+	return r & 0xffffff;
+}
+
+uchar*
+sasbhash(uchar *t, uchar *s)
+{
+	uint poly, msb, l, r, i, j;
+
+	r = 0;
+	poly = 0x01db2777;
+	msb = 0x01000000;
+	for(i = 0; i < 8; i++)
+		for(j = 0x80; j != 0; j >>= 1){
+			l = 0;
+			if(s[i] & j)
+				l = msb;
+			r <<= 1;
+			r ^= l;
+			if(r & msb)
+				r ^= poly;
+		}
+	t[0] = r>>16;
+	t[1] = r>>8;
+	t[2] = r;
+	return t;
+}
diff -Nru /sys/src/libfis/mkfile /sys/src/libfis/mkfile
--- /sys/src/libfis/mkfile	Thu Jan  1 00:00:00 1970
+++ /sys/src/libfis/mkfile	Fri Jan 17 00:00:00 2014
@@ -0,0 +1,15 @@
+</$objtype/mkfile
+
+LIB=/$objtype/lib/libfis.a
+OFILES=\
+	fis.$O\
+
+HFILES=/sys/include/fis.h
+
+UPDATE=\
+	mkfile\
+	$HFILES\
+	${OFILES:%.$O=%.c}\
+	${LIB:/$objtype/%=/386/%}\
+
+</sys/src/cmd/mksyslib
--- /sys/include/fis.h	Fri Jan 17 21:06:28 2014
+++ /sys/include/fis.h	Fri Jan 17 00:00:00 2014
@@ -0,0 +1,163 @@
+#pragma	lib	"libfis.a"
+#pragma	src	"/sys/src/libfis"
+
+/* ata errors */
+enum {
+	Emed	= 1<<0,		/* media error */
+	Enm	= 1<<1,		/* no media */
+	Eabrt	= 1<<2,		/* abort */
+	Emcr	= 1<<3,		/* media change request */
+	Eidnf	= 1<<4,		/* no user-accessible address */
+	Emc	= 1<<5,		/* media change */
+	Eunc	= 1<<6,		/* data error */
+	Ewp	= 1<<6,		/* write protect */
+	Eicrc	= 1<<7,		/* interface crc error */
+
+	Efatal	= Eidnf|Eicrc,	/* must sw reset */
+};
+
+/* ata status */
+enum {
+	ASerr	= 1<<0,		/* error */
+	ASdrq	= 1<<3,		/* request */
+	ASdf	= 1<<5,		/* fault */
+	ASdrdy	= 1<<6,		/* ready */
+	ASbsy	= 1<<7,		/* busy */
+
+	ASobs	= 1<<1|1<<2|1<<4,
+};
+
+enum {
+	/* fis types */
+	H2dev		= 0x27,
+	D2host		= 0x34,
+
+	/* fis flags bits */
+	Fiscmd		= 0x80,
+
+	/* ata bits */
+	Ataobs		= 0xa0,
+	Atalba		= 0x40,
+
+	/* nominal fis size (fits any fis) */
+	Fissize		= 0x20,
+};
+
+/* sata device-to-host (0x27) fis layout */
+enum {
+	Ftype,
+	Fflags,
+	Fcmd,
+	Ffeat,
+	Flba0,
+	Flba8,
+	Flba16,
+	Fdev,
+	Flba24,
+	Flba32,
+	Flba40,
+	Ffeat8,
+	Fsc,
+	Fsc8,
+	Ficc,		/* isochronous cmd completion */
+	Fcontrol,
+};
+
+/* sata host-to-device fis (0x34) differences */
+enum{
+	Fioport	= 1,
+	Fstatus,
+	Frerror,
+};
+
+/* ata protcol type */
+enum{
+	Pnd	= 0<<0,	/* data direction */
+	Pin	= 1<<0,
+	Pout	= 2<<0,
+	Pdatam	= 3<<0,
+
+	Ppio	= 1<<2,	/* ata protocol */
+	Pdma	= 2<<2,
+	Pdmq	= 3<<2,
+	Preset	= 4<<2,
+	Pdiag	= 5<<2,
+	Ppkt	= 6<<2,
+	Pprotom	= 7<<2,
+
+	P48	= 0<<5,	/* command “size” */
+	P28	= 1<<5,
+	Pcmdszm	= 1<<5,
+
+	Pssn	= 0<<6,	/* sector size */
+	P512	= 1<<6,
+	Pssm	= 1<<6,
+};
+
+typedef struct Sfis Sfis;
+struct Sfis {
+	ushort	feat;
+	uchar	udma;
+	uchar	speeds;
+	uint	sig;
+	uint	lsectsz;
+	uint	physshift;	/* log2(log/phys) */
+	uint	c;		/* disgusting, no? */
+	uint	h;
+	uint	s;
+};
+
+enum {
+	Dlba	= 1<<0,	/* required for sata */
+	Dllba 	= 1<<1,
+	Dsmart	= 1<<2,
+	Dpower	= 1<<3,
+	Dnop	= 1<<4,
+	Datapi	= 1<<5,
+	Datapi16= 1<<6,
+	Data8	= 1<<7,
+	Dsct	= 1<<8,
+	Dnflag	= 9,
+};
+
+enum {
+	Pspinup	= 1<<0,
+	Pidready	= 1<<1,
+};
+
+void	setfissig(Sfis*, uint);
+int	txmodefis(Sfis*, uchar*, uchar);
+int	atapirwfis(Sfis*, uchar*, uchar*, int, int);
+int	featfis(Sfis*, uchar*, uchar);
+int	flushcachefis(Sfis*, uchar*);
+int	identifyfis(Sfis*, uchar*);
+int	nopfis(Sfis*, uchar*, int);
+int	rwfis(Sfis*, uchar*, int, int, uvlong);
+void	skelfis(uchar*);
+void	sigtofis(Sfis*, uchar*);
+uvlong	fisrw(Sfis*, uchar*, int*);
+
+void	idmove(char*, ushort*, int);
+vlong	idfeat(Sfis*, ushort*);
+uvlong	idwwn(Sfis*, ushort*);
+int	idss(Sfis*, ushort*);
+int	idpuis(ushort*);
+ushort	id16(ushort*, int);
+uint	id32(ushort*, int);
+uvlong	id64(ushort*, int);
+char	*pflag(char*, char*, Sfis*);
+uint	fistosig(uchar*);
+
+/* scsi */
+typedef struct Cfis Cfis;
+struct Cfis {
+	uchar	phyid;
+	uchar	encid[8];
+	uchar	tsasaddr[8];
+	uchar	ssasaddr[8];
+	uchar	ict[2];
+};
+
+void	smpskelframe(Cfis*, uchar*, int);
+uint	sashash(uvlong);
+uchar	*sasbhash(uchar*, uchar*);
--- /n/sources/plan9/sys/src/mkfile	Fri May  9 22:24:50 2008
+++ /sys/src/mkfile	Fri Jan 17 00:00:00 2014
@@ -13,6 +13,7 @@
 	libcontrol\
 	libdisk\
 	libdraw\
+	libfis\
 	libflate\
 	libframe\
 	libgeometry\
--- /sys/man/2/fis	Fri Jan 17 21:06:29 2014
+++ /sys/man/2/fis	Fri Jan 17 00:00:00 2014
@@ -0,0 +1,348 @@
+.TH FIS 2
+.SH NAME
+setfissig, txmodefis, atapirwfis, featfis, 
+flushcachefis, identifyfis, nopfis, rwfis,
+skelfis, sigtofis, fiswr, fisrw,
+id16, id32, id64,
+idmove, idfeat, idwwn, idss, idpuis, pflag, fistosig,
+sasbhash, sashash \- SATA/SAS FIS and drive feature functions
+.de PB
+.PP
+.ft L
+.nf
+..
+.SH SYNOPSIS
+.ta \w'\fLdouble 'u +\w'\fLDatapi16 'u +\w'\fLspeeds:    'u
+.de PB
+.PP
+.ft L
+.nf
+..
+.PB
+#include <u.h>
+#include <libc.h>
+#include <fis.h>
+.PB
+enum {
+	Fissize	= 0x20,		/* nominal (fits all) fis size */
+.PB
+	Dlba	= 1<<0,
+	Dllba 	= 1<<1,
+	Dsmart	= 1<<2,
+	Dpower	= 1<<3,
+	Dnop	= 1<<4,
+	Datapi	= 1<<5,
+	Datapi16	= 1<<6,
+	Data8	= 1<<7,
+	Dsct	= 1<<8,
+};
+.PB
+enum {
+	Pspinup	= 1<<0,
+	Pidready	= 1<<1,
+};
+
+struct Sfis {
+	ushort	feat;		/* features supportd */
+	uchar	udma;		/* modes supported */
+	uchar	speeds;		/* sata: allowed speeds */
+	uint	sectsz;		/* sector size */
+	uint	phystol;		/* log2(logical/physical) */
+	uint	sig;		/* signature */
+	uint	c;		/* cylinder */
+	uint	h;		/* head */
+	uint	s;		/* sector */
+};
+.PB
+void	setfissig(Sfis *sfis, uint sig)
+.PB
+int	txmodefis(Sfis *sfis, uchar *fis, uchar mode)
+.PB
+int	featfis(Sfis *sfis, uchar *fis, uchar feat)
+.PB
+int	flushcachefis(Sfis *sfis, uchar *fis)
+.PB
+int	identifyfis(Sfis *sfis, uchar *fis)
+.PB
+int	nopfis(Sfis *sfis, uchar *fis, int srst)
+.PB
+int	fisrw(Sfis *f, uchar *fis, int *count)
+.PB
+int	rwfis(Sfis *sfis, uchar *fis, int rw, int nsect, uvlong lba)
+.PB
+int	atapirwfis(Sfis *sfis, uchar *fis, uchar *cdb, int cdblen, int ndata)
+.PB
+void	skelfis(uchar *fis)
+.PB
+void	sigtofis(Sfis *sfis, uchar *d2hfis)
+.PB
+uvlong	fisrw(Sfis *sfis, uchar *fis, int *nsect)
+.PB
+ushort	id16(ushort *id, int idx)
+.PB
+uint	id32(ushort *id, int idx)
+.PB
+uvlong	id64(ushort *id, int idx)
+.PB
+void	idmove(char *buf, ushort *ididx, int n)
+.PB
+vlong	idfeat(Sfis *sfis, ushort *id)
+.PB
+uvlong	idwwn(Sfis*, ushort *id)
+.PB
+int	idss(Sfis *sfis, ushort *id)
+.PB
+int	idpuis(ushort *id)
+.PB
+char	*pflag(char *p, char *e, Sfis *sbis)
+.PB
+uint	fistosig(uchar *fis)
+.PB
+uint	sashash(uvlong u)
+.PB
+uchar*	sasbhash(uchar *t, uchar *s)
+.SH DESCRIPTION
+The
+.B Sfis
+type describes the connection between an ATA drive and
+a Host Bus Adaptor (HBA).  The details of this connection,
+such as DMA and LBA support, and the logcal sectors per
+physical sector are used to construct the proper SATA FISes.
+.PP
+Since ATA uses a seperate sector size for addressing
+(the logical sector size) and for ECC calculations (the
+physical sector size), the library returns values based on
+the physical sector size.  This allows clients to make
+intelligent decisions about IO size without worrying about
+this implementation botch.
+.PP
+.TP 10
+.B feat
+selected features supported by the drive.  Set by
+.BR idfeat .
+.TP
+.B udma
+the UDMA modes supported by the drive.  Set by
+.BR idfeat .
+.TP
+.B speeds
+bitmaped signaling speeds supported by the device.
+SATA drives may support 1.5gbit/s, 3.0gbit/s and
+6.0gbit/s signaling.
+.TP
+.B sig
+this field contains the drive's “signature.”
+Drives that support the packet command
+set have a signature of
+.BR 0xeb140000 ,
+while conventional drives have a signature of
+.BR 0x0101 .
+The signature is set by
+.BR setfissig .
+See
+.IR sd (3)
+for more information.
+.TP
+.B "c\fP,\fP\ h\fP,\fP\ s"
+the number of physical or logical cylinders, heads and sectors claimed
+by the drive.  CHS addressing is not allowed by SATA drivers.  Set by
+.BR idfeat .
+.PP
+Typically, a client starts by filling out
+.BR sfis->sig .
+Device drivers typically have an ideosyncratic method of obtaining
+a signature.  Clients of
+.IR sd (3)
+can use special commands to obtain a signature.  Given a signature
+the client can use
+.B identifyfis
+to identify the device and finally
+.BR idfeat ,
+.B idss 
+and
+.B idwwn 
+to fill out the structure and extract the maximum LBA+1
+and the sector size.
+.PP
+The
+.IB xto fis
+functions create FISes to be sent from the host to the device.
+These are called H2D or Host to Device Register FISes.  All
+require a
+.B fis
+buffer of at least
+.B Fislen
+bytes.  The return value is the ATA protocol of the returned
+command.  For example,
+.B identifyfis
+returns
+.BR "Pin|Ppio|P28|P512" .
+.TP
+.BI setfissig( sfis\fP,\fP\ sig )
+sets the device's ATA signature.
+.TP
+.BI identifyfis( sfis\fP,\fP\ fis )
+builds an ATA
+.B IDENTIFY
+.B DEVICE
+or
+.B IDENTIFY
+.B PACKET
+.B DEVICE
+FIS, based on
+.IB sfis ->sig\fR.
+.TP
+.BI id16( id\fP,\fP\ idx "), id32, id64"
+return id word, double-world or quad-word at position
+.IR idx .
+.TP
+.BI idss( sfis\fP,\fP\ id )
+return the physical sector size of the disk.
+The physical sector size is the quanta protected
+by ECC and is never smaller than the logical
+sector size, which is used in LBA calcuations.
+.TP
+.BI idpuis( id )
+checks for PUIS (power up in standby) modes.
+Invalid id blocks return -1.  Otherwise
+.B Pspinup
+is set if the drive needs
+.B "SET FEATURES"
+subcommand 7 to return complete data and
+.B Pidready
+bit set if the id block is complete.  Both or neither bits
+may be set.
+.TP
+.BI idfeat( sfis\fP,\fP\ id )
+parses the 512-byte data block returned by
+the identify commands.  On success, the last LBA+1
+is returned.  Unparseable or unsupportable data
+blocks return -1.  Flags may be converted to a
+descriptive string with
+.BR pflag .
+.B Idss
+and
+.B idwwn
+return the sector size and World Wide Name from
+the same data.
+.TP
+.BI idmove( buf\fP,\fP\ ididx\fP,\fP\ n )
+converts an ATA string of length
+.I n
+into a null-terminated string.  Trailing
+spaces are deleted.
+.TP
+.BI fistosig( fis )
+converts a D2H FIS into a device signature.
+.TP
+.BI txmodefis( sfis\fP,\fP\ fis\fP,\fP\ mode )
+builds a
+.B "SET TRANSFER MODE"
+FIS.
+.TP
+.BI featfis( sfis\fP,\fP\ fis\fP,\fP\ feat )
+builds a
+.B "SET FEATURES"
+FIS.
+.TP
+.BI flushcachefis( sfis\fP,\fP\ fis )
+builds a
+.B "FLUSH CACHE"
+FIS.
+.TP
+.BI nopfis( sfis\fP,\fP\ fis\fP,\fP\ srst )
+builds a
+.B "NOP"
+FIS.  If
+.I srst
+is set, then out-of-band signaling is used to request
+a soft reset.  It is not expected that
+.I srst
+will be useful outside of device drivers.
+.TP
+.BI rwfis( sfis\fP,\fP\ fis\fP,\fP\ rw\fP,\fP\ nsect\fP,\fP\ lba )
+generates a FIS requesting an
+.I nsect
+i/o at
+.IR lba .
+If
+.I rw
+is non-zero, then a write is requested otherwise a
+read is requested.  The correct command to issue is
+determined by
+.I sfis .
+DMA and 48-bit (LLBA) commands are preferred.
+The inverse is
+.B fisrw
+which returns the
+.I lba
+and
+.I nsect
+given a FIS generated by
+.BR rwfis.
+.TP
+.BI atapirwfis( sfis\fP,\fP\ fis\fP,\fP\ cdb\fP,\fP\ cdlen\fP,\fP\ ndata )
+generates an ATAPI read or write FIS.  The
+.I cdb
+contains a
+.IR cdblen -byte
+SCSI Command Data Block describing an
+.IR nbyte -byte
+i/o operation.
+.TP
+.BI skelfis( fis )
+builds a skeleton
+Host-to-Device (H2D) Register FIS.
+.I Fis
+must be a buffer of at least
+.B Fislen
+bytes.
+.PP
+The
+.BI fis tox
+functions create FISes to be sent from the device to the host.
+These are called D2H or Device to Host Register FISes
+and are used to generate faux responses where actual
+communication with a device would be desirable.
+All require a
+.B fis
+buffer of at least
+.B Fislen
+bytes.
+.TP
+.BI sigtofis( sfis\fP,\fP\ d2hfis )
+builds a device signature fis from based on a device's
+.BR sfis .
+.TP
+.BI sashash( sasaddr )
+generates a 4-byte hashed SAS address from an 8 byte
+WWN.
+.TP
+.BI sasbhash( sasaddr\fP,\fP\ wwn )
+fills the buffer
+.I sasaddr
+with the hashed SAS addresse from the 8 byte buffer
+.IR wwn .
+.TP
+.BI sigtofis( sfis\fP,\fP\ d2hfis )
+.SH SOURCE
+.B /sys/src/libfis
+.SH "SEE ALSO"
+.IR atazz (8) ,
+.IR sd (3) ,
+.IR sdide (3) ,
+.IR sdahci (3) ,
+.IR sdodin (3),
+.IR smart (8) 
+.SH BUGS
+Support for CHS-style addressing is somewhat weak.
+In particular,
+.B rwfis
+does not do the usual LBA-to-CHS transations.  This
+is done by drivers that support CHS addressing.  Currently
+this is only the IDE driver.
+.PP
+The
+.B Sfis
+structure arguably could contain the LBA size,
+it is required for the correct construction of FISes.