20060303

1 files changed, 308 insertions, 0 deletions

diff --git a/os/boot/pc/8250.c b/os/boot/pc/8250.c
new file mode 100644
index 00000000..56d652f9
--- /dev/null
+++ b/os/boot/pc/8250.c
@@ -0,0 +1,308 @@
+#include "u.h"
+#include "lib.h"
+#include "mem.h"
+#include "dat.h"
+#include "fns.h"
+#include "io.h"
+
+/*
+ *  INS8250 uart
+ */
+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) */
+	Tctl=	2,		/* test control (write) */
+	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 empty */
+	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 */
+
+	Serial=	0,
+	Modem=	1,
+};
+
+typedef struct Uart	Uart;
+struct Uart
+{
+	int	port;
+	uchar	sticky[8];	/* sticky write register values */
+	uchar	txbusy;
+
+	void	(*rx)(int);	/* routine to take a received character */
+	int	(*tx)(void);	/* routine to get a character to transmit */
+
+	ulong	frame;
+	ulong	overrun;
+};
+
+static Uart com[2];
+static Uart* uart;
+
+#define UartFREQ 1843200
+
+#define uartwrreg(u,r,v)	outb((u)->port + r, (u)->sticky[r] | (v))
+#define uartrdreg(u,r)		inb((u)->port + r)
+
+/*
+ *  set the baud rate by calculating and setting the baudrate
+ *  generator constant.  This will work with fairly non-standard
+ *  baud rates.
+ */
+static void
+uartsetbaud(Uart *up, int rate)
+{
+	ulong brconst;
+
+	brconst = (UartFREQ+8*rate-1)/(16*rate);
+
+	uartwrreg(up, Format, Dra);
+	outb(up->port+Dmsb, (brconst>>8) & 0xff);
+	outb(up->port+Dlsb, brconst & 0xff);
+	uartwrreg(up, Format, 0);
+}
+
+/*
+ *  toggle DTR
+ */
+static void
+uartdtr(Uart *up, int n)
+{
+	if(n)
+		up->sticky[Mctl] |= Dtr;
+	else
+		up->sticky[Mctl] &= ~Dtr;
+	uartwrreg(up, Mctl, 0);
+}
+
+/*
+ *  toggle RTS
+ */
+static void
+uartrts(Uart *up, int n)
+{
+	if(n)
+		up->sticky[Mctl] |= Rts;
+	else
+		up->sticky[Mctl] &= ~Rts;
+	uartwrreg(up, Mctl, 0);
+}
+
+static void
+uartintr(Ureg*, void *arg)
+{
+	Uart *up;
+	int ch;
+	int s, l, loops;
+
+	up = arg;
+	for(loops = 0; loops < 1024; loops++){
+		s = uartrdreg(up, Istat);
+		switch(s & 0x3F){
+		case 6:	/* receiver line status */
+			l = uartrdreg(up, Lstat);
+			if(l & Ferror)
+				up->frame++;
+			if(l & Oerror)
+				up->overrun++;
+			break;
+	
+		case 4:	/* received data available */
+		case 12:
+			ch = inb(up->port+Data);
+			if(up->rx)
+				(*up->rx)(ch);
+			break;
+	
+		case 2:	/* transmitter empty */
+			ch = -1;
+			if(up->tx)
+				ch = (*up->tx)();
+			if(ch != -1)
+				outb(up->port+Data, ch);
+			else
+				up->txbusy = 0;
+			break;
+	
+		case 0:	/* modem status */
+			uartrdreg(up, Mstat);
+			break;
+	
+		default:
+			if(s&1)
+				return;
+			print("weird modem interrupt #%2.2ux\n", s);
+			break;
+		}
+	}
+	panic("uartintr: 0x%2.2ux\n", uartrdreg(up, Istat));
+}
+
+/*
+ *  turn on a port's interrupts.  set DTR and RTS
+ */
+static void
+uartenable(Uart *up)
+{
+	/*
+ 	 *  turn on interrupts
+	 */
+	up->sticky[Iena] = 0;
+	if(up->tx)
+		up->sticky[Iena] |= Ixmt;
+	if(up->rx)
+		up->sticky[Iena] |= Ircv|Irstat;
+	uartwrreg(up, Iena, 0);
+
+	/*
+	 *  turn on DTR and RTS
+	 */
+	uartdtr(up, 1);
+	uartrts(up, 1);
+}
+
+static void
+uartdisable(Uart* up)
+{
+	/*
+ 	 * Disable interrupts.
+	 */
+	up->sticky[Iena] = 0;
+	uartwrreg(up, Iena, 0);
+	uartdtr(up, 0);
+	uartrts(up, 0);
+}
+
+void
+uartspecial(int port, void (*rx)(int), int (*tx)(void), int baud)
+{
+	Uart *up;
+	int vector;
+
+	switch(port){
+	case 0:
+		port = 0x3F8;
+		vector = VectorUART0;
+		up = &com[0];
+		break;
+	case 1:
+		port = 0x2F8;
+		vector = VectorUART1;
+		up = &com[1];
+		break;
+	default:
+		return;
+	}
+
+	if(uart != nil && uart != up)
+		uartdisable(uart);
+	uart = up;
+
+	if(up->port == 0){
+		up->port = port;
+		setvec(vector, uartintr, up);
+	}
+
+	/*
+	 *  set rate to 9600 baud.
+	 *  8 bits/character.
+	 *  1 stop bit.
+	 *  interrupts enabled.
+	 */
+	uartsetbaud(up, 9600);
+	up->sticky[Format] = Bits8;
+	uartwrreg(up, Format, 0);
+	up->sticky[Mctl] |= Inton;
+	uartwrreg(up, Mctl, 0x0);
+
+	up->rx = rx;
+	up->tx = tx;
+	uartenable(up);
+	if(baud)
+		uartsetbaud(up, baud);
+}
+
+void
+uartputc(int c)
+{
+	int i;
+	Uart *up;
+
+	if((up = uart) == nil)
+		return;
+	for(i = 0; i < 100; i++){
+		if(uartrdreg(up, Lstat) & Outready)
+			break;
+		delay(1);
+	}
+	outb(up->port+Data, c);
+}
+
+void
+uartputs(IOQ *q, char *s, int n)
+{
+	Uart *up;
+	int c, x;
+
+	if((up = uart) == nil)
+		return;
+	while(n--){
+		if(*s == '\n')
+			q->putc(q, '\r');
+		q->putc(q, *s++);
+	}
+	x = splhi();
+	if(up->txbusy == 0 && (c = q->getc(q)) != -1){
+		uartputc(c & 0xFF);
+		up->txbusy = 1;
+	}
+	splx(x);
+}
+
+void
+uartdrain(void)
+{
+	Uart *up;
+	int timeo;
+
+	if((up = uart) == nil)
+		return;
+	for(timeo = 0; timeo < 10000 && up->txbusy; timeo++)
+		delay(1);
+}