From 6a9c500e0bfd986687fcbd9ce7cd60d262d3b951 Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Fri, 2 Sep 1994 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1994-09-02

---
 carrera/clock.c   |   1 +
 carrera/fns.h     |   7 +-
 carrera/kbd.c     |   1 +
 carrera/main.c    |   2 +-
 carrera/ns16552.h |  41 +++
 carrera/trap.c    |   4 +-
 pc/fault386.c     |   4 +-
 pc/fns.h          |   4 +-
 pc/kbd.c          |   5 +-
 pc/ns16552.h      | 147 ++++++++
 pc/trap.c         |   1 +
 port/devcons.c    |  12 +-
 port/devns16552.c | 895 ++++++++++++++++++++++++++++++++++++++++++++++
 port/devpipe.c    |   4 +-
 port/portfns.h    |   4 +-
 port/qio.c        |  44 ++-
 power/devduart.c  |   2 +-
 17 files changed, 1145 insertions(+), 33 deletions(-)
 create mode 100644 carrera/ns16552.h
 create mode 100644 pc/ns16552.h
 create mode 100644 port/devns16552.c

diff --git a/carrera/clock.c b/carrera/clock.c
index 4c2db468d23f867127cdada3646369e35a49d035..0b7c8294d4078d69a57410ebac008787cea067fd 100644
--- a/carrera/clock.c
+++ b/carrera/clock.c
@@ -91,6 +91,7 @@ clock(Ureg *ur)
 	}
 
 	checkalarms();
+	uartclock();
 	mouseclock();
 
 	if(up == 0 || up->state != Running)
diff --git a/carrera/fns.h b/carrera/fns.h
index 4123fbaeb3adc7b330b40664333f5af890e51948..86def8eb916d993710e7aab57314e4965e64bb52 100644
--- a/carrera/fns.h
+++ b/carrera/fns.h
@@ -96,6 +96,7 @@ void		vector0(void);
 void		vector100(void);
 void		vector180(void);
 void		vmereset(void);
+void		uartclock(void);
 void		uvst(void*, void*);
 void		uvld(void*, void*);
 void		wbflush(void);
@@ -103,9 +104,9 @@ void		wrcompare(ulong);
 void		Xdelay(int);
 
 void		serialinit(void);
-void		NS16552special(int, int, Queue**, Queue**, int (*)(Queue*, int));
-void		NS16552setup(ulong, ulong);
-void		NS16552intr(int);
+void		ns16552special(int, int, Queue**, Queue**, int (*)(Queue*, int));
+void		ns16552setup(ulong, ulong);
+void		ns16552intr(int);
 void		etherintr(void);
 void		iomapinit(void);
 void		enetaddr(uchar*);
diff --git a/carrera/kbd.c b/carrera/kbd.c
index 69d9fe20af89303ea6092130317eb8ea1ced6c6d..074b923bde57a9ca33798f1a4947c01df8b6f9f6 100644
--- a/carrera/kbd.c
+++ b/carrera/kbd.c
@@ -354,6 +354,7 @@ kbdinit(void)
 	int i;
 
 	kbdq = qopen(4*1024, 0, 0, 0);
+	qnoblock(kbdq, 1);
 
 	/*
 	 *  empty the buffer
diff --git a/carrera/main.c b/carrera/main.c
index 95950001b9d31f5956920039f9b26529b26a6437..1cc7996f44c8aef2d0ce231b3bde0bd3008d5e97 100644
--- a/carrera/main.c
+++ b/carrera/main.c
@@ -163,7 +163,7 @@ machinit(void)
 void
 serialinit(void)
 {
-	NS16552setup(Uart1, UartFREQ);
+	ns16552install();
 	kbdinit();
 }
 
diff --git a/carrera/ns16552.h b/carrera/ns16552.h
new file mode 100644
index 0000000000000000000000000000000000000000..bd71ce809f2d34d460e65a2753c4fdaa7114454c
--- /dev/null
+++ b/carrera/ns16552.h
@@ -0,0 +1,41 @@
+#define outb(p, ch)			*(uchar*)((p)^7) = ch	
+#define uartwrreg(u,r,v)	outb((u)->port + (r), (u)->sticky[r] | (v))
+#define uartrdreg(u,r)		*(uchar*)(((u)->port + (r))^7)
+
+#define uartpower(x, y)
+
+void
+ns16552install(void)
+{
+	static int already;
+
+	if(already)
+		return;
+	already = 1;
+
+	ns16552setup(Uart1, UartFREQ);
+}
+
+#define RD(r)	(*(uchar*)((Uart1+r)^7))
+static void
+ns16552iputc(char c)
+{
+	while((RD(5) & (1<<5)) == 0)
+		;
+	*(uchar*)(Uart1^7) = c;
+	while((RD(5) & (1<<5)) == 0)
+		;
+}
+
+int
+iprint(char *fmt, ...)
+{
+	int n, i;
+	char buf[512];
+
+	n = doprint(buf, buf+sizeof(buf), fmt, (&fmt+1)) - buf;
+	for(i = 0; i < n; i++)
+		ns16552iputc(buf[i]);
+	
+	return n;
+}
diff --git a/carrera/trap.c b/carrera/trap.c
index 04ac679aa68ae43385d3dfe12e5c078311fec910..dd476e49f9996ae7ec4e6aa47dcac72b69926aa5 100644
--- a/carrera/trap.c
+++ b/carrera/trap.c
@@ -298,10 +298,10 @@ intr(Ureg *ur)
 		default:
 			panic("unknown devint=#%lux", devint);
 		case 0x28:		/* Serial 1 */
-			NS16552intr(0);
+			ns16552intr(0);
 			break;
 		case 0x24:		/* Serial 2 */
-			NS16552intr(1);
+			ns16552intr(1);
 			break;
 		case 0x10:
 			fiberint(0);
diff --git a/pc/fault386.c b/pc/fault386.c
index 1bb9beb52fcf7e7a242a80daa8f78bf68a82f89b..5fbd8e376aabd120bda3e69ee60686748e03ec50 100644
--- a/pc/fault386.c
+++ b/pc/fault386.c
@@ -24,7 +24,6 @@ fault386(Ureg *ur, void *arg)
 	read = !(ur->ecode & 2);
 	user = (ur->cs&0xffff) == UESEL;
 	spllo();
-/*print("F%d:A#%lux:U%d:R%d|", up->pid, addr, user, read);/**/
 	n = fault(addr, read);
 	if(n < 0){
 		if(user){
@@ -33,9 +32,8 @@ fault386(Ureg *ur, void *arg)
 			postnote(up, 1, buf, NDebug);
 			return;
 		}
-print("fault: 0x%lux", addr);
 		dumpregs(ur);
-		panic("fault: 0x%lux", addr);
+		panic("fault: 0x%lux\n", addr);
 	}
 	up->insyscall = insyscall;
 }
diff --git a/pc/fns.h b/pc/fns.h
index 1fe864bf0db08f0c19455387b5cdab12290a2f8e..69f058f51f4ecc3944223b12f3b9ec92fd11c6c1 100644
--- a/pc/fns.h
+++ b/pc/fns.h
@@ -97,9 +97,7 @@ int	x86(void);
 #define KADDR(a)	((void*)((ulong)(a)|KZERO))
 #define PADDR(a)	((ulong)(a)&~KZERO)
 
-void	NS16552special(int, int, Queue**, Queue**, int (*)(Queue*, int));
-int	NS16552m3mouse(Queue*, int);
-int	NS16552mouse(Queue*, int);
+void	ns16552special(int, int, Queue**, Queue**, int (*)(Queue*, int));
 
 void	hnputl(void*, ulong v);
 void	hnputs(void*, ushort v);
diff --git a/pc/kbd.c b/pc/kbd.c
index 3c74b4ca338b4a6d906aa91460871e576abb1899..49f60631b6f0da619dc4787fa50663f8af114339 100644
--- a/pc/kbd.c
+++ b/pc/kbd.c
@@ -254,9 +254,9 @@ serialmouse(int port, char *type, int setspeed)
 	if(setspeed)
 		setspeed = 1200;
 	if(type && *type == 'M')
-		NS16552special(port, setspeed, &mouseq, 0, m3mouseputc);
+		ns16552special(port, setspeed, &mouseq, 0, m3mouseputc);
 	else
-		NS16552special(port, setspeed, &mouseq, 0, mouseputc);
+		ns16552special(port, setspeed, &mouseq, 0, mouseputc);
 	mousetype = Mouseserial;
 }
 
@@ -597,6 +597,7 @@ kbdinit(void)
 	int c;
 
 	kbdq = qopen(4*1024, 0, 0, 0);
+	qnoblock(kbdq, 1);
 
 	setvec(Kbdvec, kbdintr, 0);
 
diff --git a/pc/ns16552.h b/pc/ns16552.h
new file mode 100644
index 0000000000000000000000000000000000000000..e1f7460a5c2ea8e8ac79e3dea836e74976b50bb6
--- /dev/null
+++ b/pc/ns16552.h
@@ -0,0 +1,147 @@
+/*
+ *  PC specific code for the ns16552.  It includes support for the 2 built
+ *  in uarts plus up to 5 MP-008 8 uart ISA cards.
+ */
+enum
+{
+	Maxcard= 5,		/* max serial cards */
+	UartFREQ= 1843200,
+
+	Serial=	0,
+	Modem=	1,
+};
+
+#define uartwrreg(u,r,v)	outb((u)->port + r, (u)->sticky[r] | (v))
+#define uartrdreg(u,r)		inb((u)->port + r)
+
+void	ns16552setup(ulong, ulong);
+
+/*
+ *  definition of an optional serial card
+ */
+typedef struct Scard
+{
+	ISAConf;	/* card configuration */
+	int	first;	/* number of first port */
+} Scard;
+static Scard *scard[Maxcard]; 	/* configs for the serial card */
+
+/* power management currently only makes sense on the AT&T safari */
+static void
+uartpower(int dev, int onoff)
+{
+	switch(dev){
+	case Modem:
+		if(modem(onoff) < 0)
+			print("can't turn %s modem speaker\n", onoff?"on":"off");
+		break;
+	case Serial:
+		if(serial(onoff) < 0)
+			print("can't turn %s serial port power\n", onoff?"on":"off");
+		break;
+	}
+}
+
+/*
+ *  handle an interrupt to a single uart
+ */
+static void
+ns16552intrx(Ureg *ur, void *arg)
+{
+	USED(ur);
+
+	ns16552intr((ulong)arg);
+}
+
+/*
+ *  interrupts from the multiport card, MP-008.  A polling port
+ *  tells which of 8 devices interrupted.
+ */
+static void
+mp008intr(Ureg *ur, void *arg)
+{
+	int i, loops;
+	uchar n;
+	Scard *mp;
+
+	USED(ur);
+	mp = arg;
+	for(loops = 0;; loops++){
+		if(loops > 1024)
+			panic("mp008intr");
+		n = ~inb(mp->mem);
+		if(n == 0)
+			return;
+		for(i = 0; n; i++){
+			if(n & 1)
+				ns16552intrx(ur, uart[mp->first+i]);
+			n >>= 1;
+		}
+	}
+}
+
+/*
+ *  install the uarts (called by reset)
+ */
+static void
+ns16552install(void)
+{
+	int i, j, port;
+	Scard *sc;
+
+	/* first two ports are always there and always the normal frequency */
+	ns16552setup(0x3F8, UartFREQ);
+	setvec(Uart0vec, ns16552intrx, (void*)0);
+	ns16552setup(0x2F8, UartFREQ);
+	setvec(Uart1vec, ns16552intrx, (void*)1);
+
+	/* the rest come out of plan9.ini */
+	for(i = 0; i < Maxcard; i++){
+		sc = scard[i] = xalloc(sizeof(Scard));
+		if(isaconfig("serial", i, sc) == 0){
+			xfree(sc);
+			break;
+		}
+
+		if(strcmp(sc->type, "MP008") == 0 || strcmp(sc->type, "mp008") == 0){
+			/*
+			 *  port gives base port address for uarts
+			 *  irq is interrupt
+			 *  mem is the polling port
+			 *  size is the number of serial ports on the same polling port
+			 *  freq is the baud rate generator frequency
+			 */
+			if(sc->size == 0)
+				sc->size = 8;
+			if(sc->freq == 0)
+				sc->freq = UartFREQ;
+			sc->first = nuart;
+			setvec(Int0vec+sc->irq, mp008intr, sc);
+			port = sc->port;
+			for(j=0; j < sc->size; j++){
+				ns16552setup(port, sc->freq);
+				port += 8;
+			}
+		} else {
+			/*
+			 *  port gives base port address for the uart
+			 *  irq is interrupt
+			 *  freq is the baud rate generator frequency
+			 */
+			ns16552setup(sc->port, sc->freq);
+			setvec(Int0vec+sc->irq, ns16552intrx, (void*)(nuart-1));
+		}
+	}
+}
+
+int
+iprint(char *fmt, ...)
+{
+	char buf[PRINTSIZE];
+	int n;
+
+	n = doprint(buf, buf+sizeof(buf), fmt, (&fmt+1)) - buf;
+	screenputs(buf, n);
+
+	return n;
+}
diff --git a/pc/trap.c b/pc/trap.c
index e47c0d158ba6cb2174066b97b54159a10021dae2..23b67b2066e89ed66422e25ce54a427862b68313 100644
--- a/pc/trap.c
+++ b/pc/trap.c
@@ -346,6 +346,7 @@ dumpregs(Ureg *ur)
 
 	x = (ulong*)(ur+1);
 	dumpregs2(ur);
+	print("  CR0 %8.8lux CR2 %8.8lux\n", getcr0(), getcr2());
 	print("  magic %lux %lux %lux\n", x[0], x[1], x[2]);
 	print("  ur %lux up %lux\n", ur, up);
 }
diff --git a/port/devcons.c b/port/devcons.c
index fd01cc28c67eba6691d983766ce3f085f1fdbd9e..5ea6ba784a09ee43a888ba2c0b1a0bb7f4e6262b 100644
--- a/port/devcons.c
+++ b/port/devcons.c
@@ -34,7 +34,9 @@ void
 printinit(void)
 {
 	klogq = qopen(32*1024, 0, 0, 0);
+	qnoblock(klogq, 1);
 	lineq = qopen(2*1024, 0, 0, 0);
+	qnoblock(lineq, 1);
 }
 
 /*
@@ -73,7 +75,7 @@ putstrn0(char *str, int n, int usewrite)
 			buf[m] = '\r';
 			buf[m+1] = '\n';
 			if(usewrite)
-				qwrite(printq, buf, m+2, 0);
+				qwrite(printq, buf, m+2);
 			else {
 				x = splhi();
 				qproduce(printq, buf, m+2);
@@ -83,7 +85,7 @@ putstrn0(char *str, int n, int usewrite)
 			n -= m + 1;
 		} else {
 			if(usewrite)
-				qwrite(printq, str, n, 0);
+				qwrite(printq, str, n);
 			else {
 				x = splhi();
 				qproduce(printq, str, n);
@@ -138,7 +140,7 @@ kprint(char *fmt, ...)
 	int n;
 
 	n = doprint(buf, buf+sizeof(buf), fmt, (&fmt+1)) - buf;
-	qwrite(klogq, buf, n, 1);
+	qwrite(klogq, buf, n);
 	return n;
 }
 
@@ -540,7 +542,7 @@ consread(Chan *c, void *buf, long n, ulong offset)
 			if(kbd.x == sizeof(kbd.line) || eol){
 				if(ch == 0x04)
 					kbd.x--;
-				qwrite(lineq, kbd.line, kbd.x, 1);
+				qwrite(lineq, kbd.line, kbd.x);
 				kbd.x = 0;
 			}
 		}
@@ -743,7 +745,7 @@ conswrite(Chan *c, void *va, long n, ulong offset)
 			if(strncmp(a, "rawon", 5) == 0){
 				qlock(&kbd);
 				if(kbd.x){
-					qwrite(kbdq, kbd.line, kbd.x, 1);
+					qwrite(kbdq, kbd.line, kbd.x);
 					kbd.x = 0;
 				}
 				kbd.raw = 1;
diff --git a/port/devns16552.c b/port/devns16552.c
new file mode 100644
index 0000000000000000000000000000000000000000..bceee69920eff9ce1faa0d686879affb7712ab9e
--- /dev/null
+++ b/port/devns16552.c
@@ -0,0 +1,895 @@
+#include	"u.h"
+#include	"../port/lib.h"
+#include	"mem.h"
+#include	"dat.h"
+#include	"fns.h"
+#include	"io.h"
+#include	"../port/error.h"
+
+#include	"devtab.h"
+#include	"../port/netif.h"
+
+/*
+ *  Driver for the ns16552.
+ */
+enum
+{
+	/*
+	 *  register numbers
+	 */
+	Data=	0,		/* xmit/rcv buffer */
+	Iena=	1,		/* interrupt enable */
+	 Ircv=	(1<<0),		/*  for char rcv'd */
+	 Ixmt=	(1<<1),		/*  for xmit buffer empty */
+	 Irstat=(1<<2),		/*  for change in rcv'er status */
+	 Imstat=(1<<3),		/*  for change in modem status */
+	Istat=	2,		/* interrupt flag (read) */
+	 Fenabd=(3<<6),		/*  on if fifo's enabled */
+	Fifoctl=2,		/* fifo control (write) */
+	 Fena=	(1<<0),		/*  enable xmit/rcv fifos */
+	 Ftrig=	(1<<6),		/*  trigger after 4 input characters */
+	 Fclear=(3<<1),		/*  clear xmit & rcv fifos */
+	Format=	3,		/* byte format */
+	 Bits8=	(3<<0),		/*  8 bits/byte */
+	 Stop2=	(1<<2),		/*  2 stop bits */
+	 Pena=	(1<<3),		/*  generate parity */
+	 Peven=	(1<<4),		/*  even parity */
+	 Pforce=(1<<5),		/*  force parity */
+	 Break=	(1<<6),		/*  generate a break */
+	 Dra=	(1<<7),		/*  address the divisor */
+	Mctl=	4,		/* modem control */
+	 Dtr=	(1<<0),		/*  data terminal ready */
+	 Rts=	(1<<1),		/*  request to send */
+	 Ri=	(1<<2),		/*  ring */
+	 Inton=	(1<<3),		/*  turn on interrupts */
+	 Loop=	(1<<4),		/*  loop back */
+	Lstat=	5,		/* line status */
+	 Inready=(1<<0),	/*  receive buffer full */
+	 Oerror=(1<<1),		/*  receiver overrun */
+	 Perror=(1<<2),		/*  receiver parity error */
+	 Ferror=(1<<3),		/*  rcv framing error */
+	 Outready=(1<<5),	/*  output buffer full */
+	Mstat=	6,		/* modem status */
+	 Ctsc=	(1<<0),		/*  clear to send changed */
+	 Dsrc=	(1<<1),		/*  data set ready changed */
+	 Rire=	(1<<2),		/*  rising edge of ring indicator */
+	 Dcdc=	(1<<3),		/*  data carrier detect changed */
+	 Cts=	(1<<4),		/*  complement of clear to send line */
+	 Dsr=	(1<<5),		/*  complement of data set ready line */
+	 Ring=	(1<<6),		/*  complement of ring indicator line */
+	 Dcd=	(1<<7),		/*  complement of data carrier detect line */
+	Scratch=7,		/* scratchpad */
+	Dlsb=	0,		/* divisor lsb */
+	Dmsb=	1,		/* divisor msb */
+
+	CTLS= 023,
+	CTLQ= 021,
+
+	Stagesize= 1024,
+	Nuart=	32,		/* max per machine */
+};
+
+typedef struct Uart Uart;
+struct Uart
+{
+	QLock;
+
+	Uart	*elist;		/* next enabled interface */
+
+	uchar	sticky[8];	/* sticky write register values */
+	ulong	port;
+	Lock	plock;		/* for printing variable */
+	int	printing;	/* true if printing */
+	ulong	freq;		/* clock frequency */
+	int	opens;
+	uchar	mask;		/* bits/char */
+	uchar	istat;		/* last istat read */
+	uchar	fifoon;		/* fifo's enabled */
+	uchar	nofifo;		/* earlier chip version with nofifo */
+	int	enabled;
+	int	dev;
+
+	int	frame;
+	int	overrun;
+
+	/* flow control */
+	int	xonoff;		/* software flow control on */
+	int	blocked;
+	int	modem;		/* hardware flow control on */
+	int	cts;
+	int	ctsbackoff;
+	Rendez	r;
+
+	/* buffers */
+	int	(*putc)(Queue*, int);
+	Queue	*iq;
+	Queue	*oq;
+
+	/* staging areas to avoid some of the per character costs */
+	uchar	istage[Stagesize];
+	uchar	*ip;
+	uchar	*ie;
+
+	uchar	ostage[Stagesize];
+	uchar	*op;
+	uchar	*oe;
+};
+
+static Uart *uart[Nuart];
+static int nuart;
+
+static int haveinput;
+struct Uartalloc {
+	Lock;
+	Uart *elist;	/* list of enabled interfaces */
+} uartalloc;
+
+void ns16552intr(int);
+
+/*
+ *  pick up architecture specific routines and definitions
+ */
+#include "ns16552.h"
+
+/*
+ *  set the baud rate by calculating and setting the baudrate
+ *  generator constant.  This will work with fairly non-standard
+ *  baud rates.
+ */
+static void
+ns16552setbaud(Uart *p, int rate)
+{
+	ulong brconst;
+
+	brconst = (p->freq+8*rate-1)/(16*rate);
+
+	uartwrreg(p, Format, Dra);
+	outb(p->port + Dmsb, (brconst>>8) & 0xff);
+	outb(p->port + Dlsb, brconst & 0xff);
+	uartwrreg(p, Format, 0);
+}
+
+static void
+ns16552parity(Uart *p, char type)
+{
+	switch(type){
+	case 'e':
+		p->sticky[Format] |= Pena|Peven;
+		break;
+	case 'o':
+		p->sticky[Format] &= ~Peven;
+		p->sticky[Format] |= Pena;
+		break;
+	default:
+		p->sticky[Format] &= ~(Pena|Peven);
+		break;
+	}
+	uartwrreg(p, Format, 0);
+}
+
+/*
+ *  set bits/character, default 8
+ */
+void
+ns16552bits(Uart *p, int bits)
+{
+	if(bits < 5 || bits > 8)
+		error(Ebadarg);
+
+	p->sticky[Format] &= ~3;
+	p->sticky[Format] |= bits-5;
+
+	uartwrreg(p, Format, 0);
+}
+
+
+/*
+ *  toggle DTR
+ */
+void
+ns16552dtr(Uart *p, int n)
+{
+	if(n)
+		p->sticky[Mctl] |= Dtr;
+	else
+		p->sticky[Mctl] &= ~Dtr;
+
+	uartwrreg(p, Mctl, 0);
+}
+
+/*
+ *  toggle RTS
+ */
+void
+ns16552rts(Uart *p, int n)
+{
+	if(n)
+		p->sticky[Mctl] |= Rts;
+	else
+		p->sticky[Mctl] &= ~Rts;
+
+	uartwrreg(p, Mctl, 0);
+}
+
+/*
+ *  send break
+ */
+void
+ns16552break(Uart *p, int ms)
+{
+	if(ms == 0)
+		ms = 200;
+
+	uartwrreg(p, Format, Break);
+	tsleep(&up->sleep, return0, 0, ms);
+	uartwrreg(p, Format, 0);
+}
+
+void
+ns16552fifoon(Uart *p)
+{
+	ulong i, x, c;
+
+	if(p->nofifo)
+		return;
+
+	x = splhi();
+
+	/* empty buffer */
+	c = 0;				/* c is to to avoid an unused warning */
+	for(i = 0; i < 16; i++)
+		c = uartrdreg(p, Data);
+	USED(c);
+	ns16552intr(p->dev);
+
+	/* turn on fifo */
+	p->fifoon = 1;
+	uartwrreg(p, Fifoctl, Fena|Ftrig);
+
+	ns16552intr(p->dev);
+	USED(c);
+	if((p->istat & Fenabd) == 0){
+		/* didn't work, must be an earlier chip type */
+		p->nofifo = 1;
+	}
+		
+	splx(x);
+}
+
+/*
+ *  modem flow control on/off (rts/cts)
+ */
+void
+ns16552mflow(Uart *p, int n)
+{
+	if(n){
+		p->sticky[Iena] |= Imstat;
+		uartwrreg(p, Iena, 0);
+		p->modem = 1;
+		p->cts = uartrdreg(p, Mstat) & Cts;
+
+		/* turn on fifo's */
+		ns16552fifoon(p);
+	} else {
+		p->sticky[Iena] &= ~Imstat;
+		uartwrreg(p, Iena, 0);
+		p->modem = 0;
+		p->cts = 1;
+
+		/* turn off fifo's */
+		p->fifoon = 0;
+		uartwrreg(p, Fifoctl, 0);
+	}
+}
+
+/*
+ *  turn on a port's interrupts.  set DTR and RTS
+ */
+void
+ns16552enable(Uart *p)
+{
+	Uart **l;
+
+	if(p->enabled)
+		return;
+
+	uartpower(p->dev, 1);
+
+	/*
+ 	 *  turn on interrupts
+	 */
+	p->sticky[Iena] = Ircv | Ixmt | Irstat;
+	uartwrreg(p, Iena, 0);
+
+	/*
+	 *  turn on DTR and RTS
+	 */
+	ns16552dtr(p, 1);
+	ns16552rts(p, 1);
+
+	/*
+	 *  assume we can send
+	 */
+	p->cts = 1;
+	p->blocked = 0;
+
+	lock(&uartalloc);
+	for(l = &uartalloc.elist; *l; l = &(*l)->elist){
+		if(*l == p)
+			break;
+	}
+	if(*l == 0){
+		p->elist = uartalloc.elist;
+		uartalloc.elist = p;
+	}
+	p->enabled = 1;
+	unlock(&uartalloc);
+}
+
+/*
+ *  turn off a port's interrupts.  reset DTR and RTS
+ */
+void
+ns16552disable(Uart *p)
+{
+	Uart **l;
+
+	/*
+ 	 *  turn off interrpts
+	 */
+	p->sticky[Iena] = 0;
+	uartwrreg(p, Iena, 0);
+
+	/*
+	 *  revert to default settings
+	 */
+	p->sticky[Format] = Bits8;
+	uartwrreg(p, Format, 0);
+
+	/*
+	 *  turn off DTR, RTS, hardware flow control & fifo's
+	 */
+	ns16552dtr(p, 0);
+	ns16552rts(p, 0);
+	ns16552mflow(p, 0);
+	p->xonoff = p->blocked = 0;
+
+	uartpower(p->dev, 0);
+
+	lock(&uartalloc);
+	for(l = &uartalloc.elist; *l; l = &(*l)->elist){
+		if(*l == p){
+			*l = p->elist;
+			break;
+		}
+	}
+	p->enabled = 0;
+	unlock(&uartalloc);
+}
+
+/*
+ *  put some bytes into the local queue to avoid calling
+ *  qconsume for every character
+ */
+static int
+stageoutput(Uart *p)
+{
+	int n;
+
+	n = qconsume(p->oq, p->ostage, Stagesize);
+	if(n <= 0)
+		return 0;
+	p->op = p->ostage;
+	p->oe = p->ostage + n;
+	return n;
+}
+
+/*
+ *  (re)start output
+ */
+static void
+ns16552kick(Uart *p)
+{
+	int x, n;
+
+	x = splhi();
+	lock(&p->plock);
+	if(p->printing == 0 || (uartrdreg(p, Lstat) & Outready))
+	if(p->cts && p->blocked == 0){
+		n = 0;
+		while((uartrdreg(p, Lstat) & Outready) == 0){
+			if(++n > 10000){
+				print("stuck serial line\n");
+				break;
+			}
+		}
+		do{
+			if(p->op >= p->oe && stageoutput(p) == 0)
+				break;
+			outb(p->port + Data, *(p->op++));
+		}while(uartrdreg(p, Lstat) & Outready);
+	}
+	unlock(&p->plock);
+	splx(x);
+}
+
+/*
+ *  default is 9600 baud, 1 stop bit, 8 bit chars, no interrupts,
+ *  transmit and receive enabled, interrupts disabled.
+ */
+static void
+ns16552setup0(Uart *p)
+{
+	memset(p->sticky, 0, sizeof(p->sticky));
+	/*
+	 *  set rate to 9600 baud.
+	 *  8 bits/character.
+	 *  1 stop bit.
+	 *  interrpts enabled.
+	 */
+	p->sticky[Format] = Bits8;
+	uartwrreg(p, Format, 0);
+	p->sticky[Mctl] |= Inton;
+	uartwrreg(p, Mctl, 0x0);
+
+	ns16552setbaud(p, 9600);
+
+	p->iq = qopen(4*1024, 0, 0, 0);
+	p->oq = qopen(4*1024, 0, ns16552kick, p);
+
+	p->ip = p->istage;
+	p->ie = &p->istage[Stagesize];
+	p->op = p->ostage;
+	p->oe = p->ostage;
+}
+
+/*
+ *  called by main() to create a new duart
+ */
+void
+ns16552setup(ulong port, ulong freq)
+{
+	Uart *p;
+
+	if(nuart >= Nuart)
+		return;
+
+	p = xalloc(sizeof(Uart));
+	uart[nuart] = p;
+	p->dev = nuart;
+	nuart++;
+	p->port = port;
+	p->freq = freq;
+	ns16552setup0(p);
+}
+
+/*
+ *  called by main() to configure a duart port as a console or a mouse
+ */
+void
+ns16552special(int port, int baud, Queue **in, Queue **out, int (*putc)(Queue*, int))
+{
+	Uart *p = uart[port];
+
+	ns16552enable(p);
+	if(baud)
+		ns16552setbaud(p, baud);
+	p->putc = putc;
+	if(in)
+		*in = p->iq;
+	if(out)
+		*out = p->oq;
+	p->opens++;
+}
+
+/*
+ *  handle an interrupt to a single uart
+ */
+void
+ns16552intr(int dev)
+{
+	uchar ch;
+	int s, l, loops;
+	Uart *p = uart[dev];
+
+	for(loops = 0;; loops++){
+		if(loops > 100000)
+			panic("ns16552intr");
+		p->istat = s = uartrdreg(p, Istat);
+		switch(s&0x3f){
+		case 6:	/* receiver line status */
+			l = uartrdreg(p, Lstat);
+			if(l & Ferror)
+				p->frame++;
+			if(l & Oerror)
+				p->overrun++;
+			break;
+	
+		case 4:	/* received data available */
+		case 12:
+			ch = uartrdreg(p, Data) & 0xff;
+			if(p->xonoff){
+				if(ch == CTLS){
+					p->blocked = 1;
+				}else if (ch == CTLQ){
+					p->blocked = 0;
+					 /* clock gets output going again */
+				}
+			}
+			if(p->putc)
+				(*p->putc)(p->iq, ch);
+			else {
+				if(p->ip < p->ie)
+					*p->ip++ = ch;
+				haveinput = 1;
+			}
+			break;
+	
+		case 2:	/* transmitter not full */
+			lock(&p->plock);
+			l = uartrdreg(p, Lstat) & Outready;
+			if(l && p->cts && p->blocked == 0)
+			if(p->op < p->oe || stageoutput(p)){
+				do{
+					outb(p->port + Data, *(p->op++));
+					if(p->op >= p->oe && stageoutput(p) == 0)
+						break;
+					l = uartrdreg(p, Lstat) & Outready;
+				}while(l);
+			}
+			if(l)
+				p->printing = 0;
+			unlock(&p->plock);
+			break;
+	
+		case 0:	/* modem status */
+			ch = uartrdreg(p, Mstat);
+			if(ch & Ctsc){
+				p->cts = ch & Cts; /* clock gets output going again */
+				p->ctsbackoff += 1;
+			}
+			break;
+	
+		default:
+			if(s&1)
+				return;
+			print("weird modem interrupt #%2.2ux\n", s);
+			break;
+		}
+	}
+}
+
+/*
+ *  we save up input characters till clock time
+ *
+ *  There's also a bit of code to get a stalled print going.
+ *  It shouldn't happen, but it does.  Obviously I don't
+ *  understand interrupts. -- presotto
+ */
+void
+uartclock(void)
+{
+	int n;
+	Uart *p;
+
+	for(p = uartalloc.elist; p; p = p->elist){
+		ns16552intr(p->dev);
+		if(haveinput){
+			n = p->ip - p->istage;
+			if(n > 0 && p->iq){
+				if(n > Stagesize)
+					panic("uartclock");
+				if(qproduce(p->iq, p->istage, n) != n)
+					;
+				p->ip = p->istage;
+			}
+		}
+		if(p->ctsbackoff-- < 0){
+			p->ctsbackoff = 0;
+			ns16552kick(p);
+		}
+	}
+	haveinput = 0;
+}
+
+Dirtab *ns16552dir;
+
+/*
+ *  all uarts must be ns16552setup() by this point or inside of ns16552install()
+ */
+void
+ns16552reset(void)
+{
+	int i;
+	Dirtab *dp;
+
+	ns16552install();	/* architecture specific */
+
+	ns16552dir = xalloc(3 * nuart * sizeof(Dirtab));
+	dp = ns16552dir;
+	for(i = 0; i < nuart; i++){
+		/* 3 directory entries per port */
+		sprint(dp->name, "eia%d", i);
+		dp->qid.path = NETQID(i, Ndataqid);
+		dp->perm = 0666;
+		dp++;
+		sprint(dp->name, "eia%dctl", i);
+		dp->qid.path = NETQID(i, Nctlqid);
+		dp->perm = 0666;
+		dp++;
+		sprint(dp->name, "eia%dstat", i);
+		dp->qid.path = NETQID(i, Nstatqid);
+		dp->perm = 0444;
+		dp++;
+	}
+}
+
+void
+ns16552init(void)
+{
+}
+
+Chan*
+ns16552attach(char *spec)
+{
+	return devattach('t', spec);
+}
+
+Chan*
+ns16552clone(Chan *c, Chan *nc)
+{
+	return devclone(c, nc);
+}
+
+int
+ns16552walk(Chan *c, char *name)
+{
+	return devwalk(c, name, ns16552dir, 3*nuart, devgen);
+}
+
+void
+ns16552stat(Chan *c, char *dp)
+{
+	int i;
+	Uart *p;
+	Dir dir;
+
+	i = NETID(c->qid.path);
+	switch(NETTYPE(c->qid.path)){
+	case Ndataqid:
+		p = uart[i];
+		devdir(c, c->qid, ns16552dir[3*i].name, qlen(p->iq), eve, 0660, &dir);
+		convD2M(&dir, dp);
+		break;
+	default:
+		devstat(c, dp, ns16552dir, 3*nuart, devgen);
+		break;
+	}
+}
+
+Chan*
+ns16552open(Chan *c, int omode)
+{
+	Uart *p;
+
+	if(c->qid.path & CHDIR){
+		if(omode != OREAD)
+			error(Ebadarg);
+	} else if(NETTYPE(c->qid.path) == Nstatqid){
+		;
+	} else {
+		p = uart[NETID(c->qid.path)];
+		qlock(p);
+		p->opens++;
+		ns16552enable(p);
+		qreopen(p->iq);
+		qreopen(p->oq);
+		qunlock(p);
+	}
+
+	c->mode = omode&~OTRUNC;
+	c->flag |= COPEN;
+	c->offset = 0;
+	return c;
+}
+
+void
+ns16552create(Chan *c, char *name, int omode, ulong perm)
+{
+	USED(c, name, omode, perm);
+	error(Eperm);
+}
+
+void
+ns16552close(Chan *c)
+{
+	Uart *p;
+
+	if(c->qid.path & CHDIR)
+		return;
+	if(NETTYPE(c->qid.path) == Nstatqid)
+		return;
+
+	p = uart[NETID(c->qid.path)];
+	if(c->flag & COPEN){
+		qlock(p);
+		p->opens--;
+		if(p->opens == 0){
+			ns16552disable(p);
+			qclose(p->iq);
+			qclose(p->oq);
+			p->ip = p->istage;
+		}
+		qunlock(p);
+	}
+}
+
+static long
+uartstatus(Chan *c, Uart *p, void *buf, long n, long offset)
+{
+	uchar mstat;
+	uchar tstat;
+	char str[256];
+	int i;
+
+	str[0] = 0;
+	tstat = p->sticky[Mctl];
+	mstat = uartrdreg(p, Mstat);
+	i = sprint(str, "%d printing %d cts %d qlen %d/%d", NETID(c->qid.path),
+		p->printing, p->cts, qlen(p->iq), qlen(p->oq));
+	sprint(str+i, " lstat %ux mstat %ux istat %ux ier %ux ferr %d oerr %d",
+		uartrdreg(p, Lstat), mstat, uartrdreg(p, Istat), uartrdreg(p, Iena),
+		p->frame, p->overrun);
+	if(mstat & Cts)
+		strcat(str, " cts");
+	if(mstat & Dsr)
+		strcat(str, " dsr");
+	if(mstat & Ring)
+		strcat(str, " ring");
+	if(mstat & Dcd)
+		strcat(str, " dcd");
+	if(tstat & Dtr)
+		strcat(str, " dtr");
+	if(tstat & Rts)
+		strcat(str, " rts");
+	strcat(str, "\n");
+	return readstr(offset, buf, n, str);
+}
+
+long
+ns16552read(Chan *c, void *buf, long n, ulong offset)
+{
+	Uart *p;
+
+	if(c->qid.path & CHDIR)
+		return devdirread(c, buf, n, ns16552dir, 3*nuart, devgen);
+
+	p = uart[NETID(c->qid.path)];
+	switch(NETTYPE(c->qid.path)){
+	case Ndataqid:
+		return qread(p->iq, buf, n);
+	case Nctlqid:
+		return readnum(offset, buf, n, NETID(c->qid.path), NUMSIZE);
+	case Nstatqid:
+		return uartstatus(c, p, buf, n, offset);
+	}
+
+	return 0;
+}
+
+static void
+ns16552ctl(Uart *p, char *cmd)
+{
+	int i, n;
+
+	/* let output drain for a while */
+	for(i = 0; i < 16 && qlen(p->oq); i++)
+		tsleep(&p->r, qlen, p->oq, 125);
+
+	if(strncmp(cmd, "break", 5) == 0){
+		ns16552break(p, 0);
+		return;
+	}
+		
+
+	n = atoi(cmd+1);
+	switch(*cmd){
+	case 'B':
+	case 'b':
+		ns16552setbaud(p, n);
+		break;
+	case 'D':
+	case 'd':
+		ns16552dtr(p, n);
+		break;
+	case 'H':
+	case 'h':
+		qhangup(p->iq);
+		qhangup(p->oq);
+		break;
+	case 'L':
+	case 'l':
+		ns16552bits(p, n);
+		break;
+	case 'm':
+	case 'M':
+		ns16552mflow(p, n);
+		break;
+	case 'n':
+	case 'N':
+		qnoblock(p->oq, n);
+		break;
+	case 'P':
+	case 'p':
+		ns16552parity(p, *(cmd+1));
+		break;
+	case 'K':
+	case 'k':
+		ns16552break(p, n);
+		break;
+	case 'R':
+	case 'r':
+		ns16552rts(p, n);
+		break;
+	case 'Q':
+	case 'q':
+		qsetlimit(p->iq, n);
+		qsetlimit(p->oq, n);
+		break;
+	case 'W':
+	case 'w':
+		/* obsolete */
+		break;
+	case 'X':
+	case 'x':
+		p->xonoff = n;
+		break;
+	}
+}
+
+long
+ns16552write(Chan *c, void *buf, long n, ulong offset)
+{
+	Uart *p;
+	char cmd[32];
+
+	USED(offset);
+
+	if(c->qid.path & CHDIR)
+		error(Eperm);
+
+	p = uart[NETID(c->qid.path)];
+
+	/*
+	 *  The fifo's turn themselves off sometimes.
+	 *  It must be something I don't understand. -- presotto
+	 */
+	if((p->istat & Fenabd) == 0 && p->fifoon && p->nofifo == 0)
+		ns16552fifoon(p);
+
+	switch(NETTYPE(c->qid.path)){
+	case Ndataqid:
+		return qwrite(p->oq, buf, n);
+	case Nctlqid:
+		if(n >= sizeof(cmd))
+			n = sizeof(cmd)-1;
+		memmove(cmd, buf, n);
+		cmd[n] = 0;
+		ns16552ctl(p, cmd);
+		return n;
+	}
+}
+
+void
+ns16552remove(Chan *c)
+{
+	USED(c);
+	error(Eperm);
+}
+
+void
+ns16552wstat(Chan *c, char *dp)
+{
+	USED(c, dp);
+	error(Eperm);
+}
diff --git a/port/devpipe.c b/port/devpipe.c
index 8f99eeefbb52ad3bc2f2de47bca61dfe618b7dd6..cef15394661feb1adcaf17022c34138d795ab650 100644
--- a/port/devpipe.c
+++ b/port/devpipe.c
@@ -313,11 +313,11 @@ pipewrite(Chan *c, void *va, long n, ulong offset)
 
 	switch(NETTYPE(c->qid.path)){
 	case Qdata0:
-		n = qwrite(p->q[1], va, n, 0);
+		n = qwrite(p->q[1], va, n);
 		break;
 
 	case Qdata1:
-		n = qwrite(p->q[0], va, n, 0);
+		n = qwrite(p->q[0], va, n);
 		break;
 
 	default:
diff --git a/port/portfns.h b/port/portfns.h
index 67eba9326721f1d425c5ea6c26b45364eefa710f..531928cb123c081e850763a89ec338c426761bf5 100644
--- a/port/portfns.h
+++ b/port/portfns.h
@@ -202,7 +202,9 @@ long		qread(Queue*, void*, int);
 void		qreopen(Queue*);
 void		qunlock(QLock*);
 int		qwindow(Queue*);
-long		qwrite(Queue*, void*, int, int);
+long		qwrite(Queue*, void*, int);
+void		qsetlimit(Queue*, int);
+void		qnoblock(Queue*, int);
 int		readnum(ulong, char*, ulong, ulong, int);
 int		readstr(ulong, char*, ulong, char*);
 void		ready(Proc*);
diff --git a/port/qio.c b/port/qio.c
index 75e0a8a9cc0fd3c370caab92a882e9f55b7821aa..264307c837a0fb951b636e47f4a21fb2df3d698d 100644
--- a/port/qio.c
+++ b/port/qio.c
@@ -13,6 +13,8 @@ struct
 
 static int debuging;
 
+#define QDEBUG if(0)
+
 /*
  *  IO queues
  */
@@ -27,7 +29,9 @@ struct Queue
 
 	int	len;		/* bytes in queue */
 	int	limit;		/* max bytes in queue */
+	int	inilim;		/* initial limit */
 	int	state;
+	int	noblock;	/* true if writes return immediately when q full */
 	int	eof;		/* number of eofs read by user */
 
 	void	(*kick)(void*);	/* restart output */
@@ -172,7 +176,7 @@ qconsume(Queue *q, void *vp, int len)
 		unlock(q);
 		return -1;
 	}
-checkb(b, "qconsume 1");
+	QDEBUG checkb(b, "qconsume 1");
 
 	n = BLEN(b);
 	if(n < len)
@@ -195,7 +199,7 @@ checkb(b, "qconsume 1");
 	if(dowakeup)
 		wakeup(&q->wr);
 
-checkb(b, "qconsume 2");
+	QDEBUG checkb(b, "qconsume 2");
 	/* discard the block if we're done with it */
 	if((q->state & Qmsg) || len == n)
 		freeb(b);
@@ -238,7 +242,7 @@ qpass(Queue *q, Block *b)
 		q->bfirst = b;
 	q->blast = b;
 	q->len += len;
-checkb(b, "qpass");
+	QDEBUG checkb(b, "qpass");
 
 	if(q->len >= q->limit/2)
 		q->state |= Qflow;
@@ -308,7 +312,7 @@ qproduce(Queue *q, void *vp, int len)
 		q->bfirst = b;
 	q->blast = b;
 	q->len += len;
-checkb(b, "qproduce");
+	QDEBUG checkb(b, "qproduce");
 
 	if(q->state & Qstarve){
 		q->state &= ~Qstarve;
@@ -337,7 +341,7 @@ qopen(int limit, int msg, void (*kick)(void*), void *arg)
 	if(q == 0)
 		return 0;
 
-	q->limit = limit;
+	q->limit = q->inilim = limit;
 	q->kick = kick;
 	q->arg = arg;
 	q->state = msg ? Qmsg : 0;
@@ -422,7 +426,7 @@ qread(Queue *q, void *vp, int len)
 			sleep(&q->rr, notempty, q);
 		}
 	}
-checkb(b, "qread 1");
+	QDEBUG checkb(b, "qread 1");
 
 	/* remove a buffered block */
 	q->bfirst = b->next;
@@ -443,7 +447,7 @@ checkb(b, "qread 1");
 	memmove(p, b->rp, n);
 	b->rp += n;
 
-checkb(b, "qread 2");
+	QDEBUG checkb(b, "qread 2");
 	/* free it or put what's left on the queue */
 	if(b->rp >= b->wp || (q->state&Qmsg)) {
 		freeb(b);
@@ -482,7 +486,7 @@ qnotfull(void *a)
  *  all copies should be outside of ilock since they can fault.
  */
 long
-qwrite(Queue *q, void *vp, int len, int nowait)
+qwrite(Queue *q, void *vp, int len)
 {
 	int n, sofar, dowakeup;
 	Block *b;
@@ -530,7 +534,7 @@ qwrite(Queue *q, void *vp, int len, int nowait)
 	
 		/* flow control */
 		while(!qnotfull(q)){
-			if(nowait){
+			if(q->noblock){
 				freeb(b);
 				qunlock(&q->wlock);
 				poperror();
@@ -549,7 +553,7 @@ qwrite(Queue *q, void *vp, int len, int nowait)
 		}
 		poperror();
 
-checkb(b, "qwrite");
+		QDEBUG checkb(b, "qwrite");
 		if(q->syncbuf){
 			/* we guessed wrong and did an extra copy */
 			if(n > q->synclen)
@@ -645,6 +649,8 @@ qreopen(Queue *q)
 	q->state &= ~Qclosed;
 	q->state |= Qstarve;
 	q->eof = 0;
+	q->noblock = 0;
+	q->limit = q->inilim;
 }
 
 /*
@@ -678,3 +684,21 @@ qcanread(Queue *q)
 {
 	return q->bfirst!=0;
 }
+
+/*
+ *  change queue limit
+ */
+void
+qsetlimit(Queue *q, int limit)
+{
+	q->limit = limit;
+}
+
+/*
+ *  set blocking/nonblocking
+ */
+void
+qnoblock(Queue *q, int onoff)
+{
+	q->noblock = onoff;
+}
diff --git a/power/devduart.c b/power/devduart.c
index 5292028e1b5c08401658314fa07ae73e247ae690..896386994c310515fffaa7f39ee5917e2f5966a8 100644
--- a/power/devduart.c
+++ b/power/devduart.c
@@ -672,7 +672,7 @@ duartwrite(Chan *c, void *va, long n, ulong offset)
 	p = &uart[NETID(c->qid.path)];
 	switch(NETTYPE(c->qid.path)){
 	case Ndataqid:
-		return qwrite(p->oq, va, n, 0);
+		return qwrite(p->oq, va, n);
 	case Nctlqid:
 		if(n >= sizeof(cmd))
 			n = sizeof(cmd)-1;