use the portable 8250 uart code.  this also fixes console printing oddities.

Reference: /n/atom/patch/applied2013/rbserial
Date: Mon Aug  5 03:36:53 CES 2013
Signed-off-by: quanstro@quanstro.net

--- /sys/src/9/rb/main.c	Mon Aug  5 03:36:24 2013
+++ /sys/src/9/rb/main.c	Mon Aug  5 03:36:25 2013
@@ -11,6 +11,7 @@
 #include	<bootexec.h>
 #include	"reboot.h"
 
+extern	char	bootmethod[];
 usize	segpgsizes = (1<<PGSHIFT);	/* only page size available */
 
 enum {
@@ -42,8 +43,11 @@
 int normalprint;
 
 char *
-getconf(char *)
+getconf(char *name)
 {
+	if(strcmp(name, "console") == 0)
+	//	return "0 b115200 l8 pn m0 s1 i128 w100";	/* baud setting fails; don't do it */
+		return "0 l8 pn m0 s1 i128 w100";
 	return nil;	/* stub */
 }
 
@@ -178,7 +182,7 @@
 	printinit();
 	fmtinit();
 	vecinit();
-
+	i8250console();			/* required for rbuart.c */
 	normalprint = 1;
 	print("\nPlan 9\n");
 	prcpuid();
@@ -267,7 +271,7 @@
 		 * we don't have a good way to read our cfg file in
 		 * RouterBOOT, so set the configuration here.
 		 */
-		ksetenv("nobootprompt", "tcp", 0);
+		ksetenv("nobootprompt", bootmethod, 0);	/* see rb config file */
 		ksetenv("nvram", "/boot/nvram", 0);
 		poperror();
 	}
--- /sys/src/9/rb/uartrb.c	Thu Jan  1 00:00:00 1970
+++ /sys/src/9/rb/uartrb.c	Mon Aug  5 03:36:25 2013
@@ -0,0 +1,140 @@
+#include "u.h"
+#include "../port/lib.h"
+#include "mem.h"
+#include "dat.h"
+#include "fns.h"
+#include "io.h"
+#include "../port/error.h"
+#include "../port/uartp8250.h"
+
+extern PhysUart rbphysuart;	/* BOTCH; should use p8250 directly */
+
+void
+wave(char *s)
+{
+	u32int *io;
+
+	io = (u32int*)PHYSCONS;
+	for(; *s; s++){
+		io[Thr] = *s;
+		microdelay(100);
+	}
+}
+
+void
+waveprint(char *fmt, ...)
+{
+	va_list arg;
+	char buf[PRINTSIZE];
+
+	va_start(arg, fmt);
+	vseprint(buf, buf+sizeof(buf), fmt, arg);
+	va_end(arg);
+	wave(buf);
+}
+
+static uint
+ioget(void *v, int i)
+{
+	u32int *io;
+
+	io = v;
+	return io[i];
+}
+
+static void
+ioset(void *v, int i, uint x)
+{
+	u32int *io;
+
+	io = v;
+	io[i] = x;
+}
+
+static void
+rbinterrupt(void *v)
+{
+	i8250interrupt(nil, v);
+}
+
+static int
+itr(Uart *u, int on)
+{
+	Ctlr *c;
+
+	c = u->regs;
+	if(on)
+		intrenable(c->irq, rbinterrupt, u /*, u->name*/);
+	else
+		/* this causes hangs. please debug. (on a pc; not tried yet) */
+//		return intrdisable(c->irq, rbinterrupt, u, u->name);
+		return -1;
+	return 0;
+}
+
+PhysUart rbphysuart;
+
+static Ctlr rbctlr = {
+	.reg	= (void*)PHYSCONS,
+	.get	= ioget,
+	.set	= ioset,
+	.itr	= itr,
+	.irq	= ILduart0,
+};
+
+static Uart rbuart = {
+	.regs	= &rbctlr,
+	.name	= "cons",
+	.freq	= 3686000,	/* Not used, we use the global i8250freq */
+	.baud	= 115200,	/* switching doesn't work */
+	.phys	= &rbphysuart,
+	.special	= 1,
+	.console	= 0,
+	.next	= nil,
+};
+
+static Uart*
+rb8250pnp(void)
+{
+	return &rbuart;
+}
+
+void*
+i8250alloc(int io, int irq, int tbdf)
+{
+	Ctlr *ctlr;
+
+	if((ctlr = malloc(sizeof(Ctlr))) != nil){
+		ctlr->reg = (void*)io;
+		ctlr->irq = irq;
+		ctlr->tbdf = tbdf;
+		ctlr->get = ioget;
+		ctlr->set = ioset;
+		ctlr->itr = itr;
+	}
+	return ctlr;
+}
+
+int
+i8250console(void)
+{
+	int n;
+	char *cmd;
+	static int once;
+
+	if(once == 0){
+		once = 1;
+		memmove(&rbphysuart, &p8250physuart, sizeof(PhysUart));
+		rbphysuart.name = "rb";
+		rbphysuart.pnp = rb8250pnp;
+	}
+
+	n = uartconsconf(&cmd);
+	if(n == 0){
+		qlock(&rbuart);
+		uartctl(&rbuart, "z");
+		uartctl(&rbuart, cmd);
+		qunlock(&rbuart);
+	}
+	return 0;
+}