basic support for ahci 1.3.1.  it looks like device sleep is the main
change from 1.3, and to first approximation it looks like the right
thing to do is recognize it, and turn it off.

Reference: /n/atom/patch/applied2013/ahci131intro
Date: Sat Dec 21 05:32:35 CET 2013
Signed-off-by: quanstro@quanstro.net

--- /sys/src/nix/k10/ahci.h	Sat Dec 21 05:29:38 2013
+++ /sys/src/nix/k10/ahci.h	Sat Dec 21 05:29:39 2013
@@ -52,6 +52,9 @@
 
 /* cap2 bits */
 enum {
+	Dseo	= 1<<5,	/* sleep entrance from slumber only */
+	Sadm	= 1<<4,	/* aggressive sleep mgmt */
+	Sds	= 1<<3,	/* device sleep supported */
 	Apts	= 1<<2,	/* automatic partial to slumber */
 	Nvmp	= 1<<1,	/* nvmhci present; nvram */
 	Boh	= 1<<0,	/* bios/os handoff supported */
@@ -165,12 +168,12 @@
 	Acr	= 1<<15,	/* cmdlist running */
 	Afr	= 1<<14,	/* fis running */
 	Ampss	= 1<<13,	/* mechanical presence switch state */
-	Accs	= 1<<8,		/* current command slot 12:08 */
-	Afre	= 1<<4,		/* fis enable receive */
-	Aclo	= 1<<3,		/* command list override */
-	Apod	= 1<<2,		/* power on dev (requires cold-pres. detect) */
-	Asud	= 1<<1,		/* spin-up device;  requires ss capability */
-	Ast	= 1<<0,		/* start */
+	Accs	= 1<<8,	/* current command slot 12:08 */
+	Afre	= 1<<4,	/* fis enable receive */
+	Aclo	= 1<<3,	/* command list override */
+	Apod	= 1<<2,	/* power on dev (requires cold-pres. detect) */
+	Asud	= 1<<1,	/* spin-up device;  requires ss capability */
+	Ast	= 1<<0,	/* start */
 
 	Arun	= Ast|Acr|Afre|Afr,
 	Apwr	= Apod|Asud,
@@ -184,7 +187,7 @@
 };
 
 /* sstatus register bits */
-enum{
+enum {
 	/* sstatus det */
 	Smissing		= 0<<0,
 	Spresent		= 1<<0,
@@ -204,12 +207,33 @@
 	Iactive		= 1<<8,
 	Isleepy		= 2<<8,
 	Islumber		= 6<<8,
-	Imask		= 7<<8,
+	Isleep		= 8<<8,
+	Imask		= 15<<8,
 
 	SImask		= Smask | Imask,
 	SSmask		= Smask | Isleepy,
 };
 
+/* fbs register bits */
+enum {
+	Dwe		= 1<<16,		/* device with error 4 bits */
+	Ado		= 1<<12,		/* active dev optimization 4 bits */
+	D2issue		= 1<<8,		/* device to issue 4 bits */
+	Sde		= 1<<2,		/* single device error */
+	Dec		= 1<<1,		/* device error clear (r1c) */
+	Fbsen		= 1<<0,		/* enable switching */
+};
+
+/* devslp register bits */
+enum {
+	Ditom		= 1<<25,		/* dito multiplier (4 bits) */
+	Dito		= 1<<15,		/* idle timeout (10 bits) */
+	Mdat		= 1<<10,		/* minimum sleep assertion time */
+	Deto		= 1<<2,		/* exit timeout (8 bits) ms */
+	Dsp		= 1<<1,		/* present */
+	Asde		= 1<<0,		/* enable */
+};
+
 #define	sstatus	scr0
 #define	sctl	scr2
 #define	serror	scr1
@@ -234,7 +258,8 @@
 	u32int	ci;		/* command issue */
 	u32int	scr4;
 	u32int	fbs;
-	u32int	res2[11];
+	u32int	devslp;
+	u32int	res2[10];
 	u32int	vendor[4];
 } Aport;
 
--- /sys/src/nix/k10/sdahci.c	Sat Dec 21 05:29:42 2013
+++ /sys/src/nix/k10/sdahci.c	Sat Dec 21 05:29:43 2013
@@ -312,9 +312,9 @@
 			break;
 		asleep(25);
 	}
-	p->sctl = 3*Aipm | 0*Aspd | Adet;
+	p->sctl = 7*Aipm | 0*Aspd | Adet;
 	delay(1);
-	p->sctl = 3*Aipm | mode*Aspd;
+	p->sctl = 7*Aipm | mode*Aspd;
 	return 0;
 }
 
@@ -506,10 +506,10 @@
 
 	p->serror = SerrAll;
 
-	if((p->sstatus & SSmask) == (Isleepy | Spresent))
+	if((p->sstatus & SSmask) == (Isleep | Isleepy | Spresent))
 		ahciwakeup(c, mode);
 	/* disable power managment sequence from book. */
-	p->sctl = 3*Aipm | mode*Aspd | 0*Adet;
+	p->sctl = 7*Aipm | mode*Aspd | 0*Adet;
 	p->cmd &= ~Aalpe;
 
 	p->cmd |= Ast;
@@ -2068,6 +2068,9 @@
 };
 
 static Htab htab2[] = {
+	Dseo,	"dseo",
+	Sadm,	"sadm",
+	Sds,	"sds",
 	Apts,	"apts",
 	Nvmp,	"nvmp",
 	Boh,	"boh",