p16c552.c

mips架构的bootloader,99左右的版本 但源代码现在没人更新了

/*************************************************************
 * File: lib/p16C552.c
 * Purpose: Part of C runtime library
 * Author: Phil Bunce ([e-mail])
 * Revision History:
 *	980304	Created
 *	990118	Added BAUDRATES
 */

#include <mips.h>
/* 
 * Polled I/O routines for the National NS16C552 DUART on the CMA101
 * Motherboard from Cogent Computer Systems, Inc.
 *
 */

#include <terms.h>
#include <utypes.h>


/* btab = sysclk/(baudrate*N)  */
static long btab[] = {
	-1, 	/* B0 */
	-1,	/* B50 */
	3072,	/* B75 */
	-1,	/* B110 */
	-1,	/* B134 */
	1536,	/* B150 */
	1152,	/* B200 */
	768,	/* B300 */
	384,	/* B600 */
	192,	/* B1200 */
	128,	/* B1800 */
	96,	/* B2400 */
	48,	/* B4800 */
	24,	/* B9600 */
	12,	/* B19200 */
	6,	/* B38400 */
	0 };

#define DEFRATE		13 /* default baudrate (9600) */

/* The base address shouldn't really be hardwired like this. I should
 * define the value in devinfo.c, and pass the address to the driver.
 */
#ifdef MIPSEB
#define DUART_BASE	0xbe900007
#else
#define DUART_BASE	0xbe900000
#endif

#define inb(a)      (*((volatile Uchar *)(a)))
#define inh(a)      (*((volatile Ushort *)(a)))
#define outb(a,v)      (*((volatile Uchar *)(a))=(v))
#define outh(a,v)      (*((volatile Ushort *)(a))=(v))
#define outw(a,v)      (*((volatile Ulong *)(a))=(v))

#define RXRDY	0x01
#define TXRDY	0x20

/* This driver is a for a 64-bit processor. So the DUART's registers
 * are 8 bytes apart, rather than the usual 4 bytes for a 32-bit CPU.
 */
#define STATUS	(8*5)
#define RXHR	(8*0)
#define TXHR	(8*0)

/*************************************************************
*  p16c552(op,siodat,chan,ch)
*/
p16c552(op,siodat,chan,ch)
int op,chan,ch;
void *siodat;
{
int i,brate;
Ulong m,v;

switch (op) {
	case OP_RXRDY : 
		if (inb(DUART_BASE+STATUS+((chan)?0:0x40))&RXRDY) return(1);
		break;

	case OP_RX :
		return inb(DUART_BASE+RXHR+((chan)?0:0x40));

	case OP_TXRDY :
		if (inb(DUART_BASE+STATUS+((chan)?0:0x40))&TXRDY) return(1);
		break;

	case OP_TX :
		outb(DUART_BASE+TXHR+((chan)?0:0x40),ch);
		break;

	case OP_INIT : 
		for (i=0;i<2;i++) { /* for each channel (2) */
			/* set DLAB */
			outb(DUART_BASE+(3*8)+((i)?0:0x40),0x80);
			/* ms baud */
			outb(DUART_BASE+(1*8)+((i)?0:0x40),btab[DEFRATE]>>8); 
			/* ls baud */
			outb(DUART_BASE+(0*8)+((i)?0:0x40),btab[DEFRATE]&0xff);
			/* mode: 2 stopbits, no parity, 8 bitsdata */
			outb(DUART_BASE+(3*8)+((i)?0:0x40),0x03);
			}
		break;
	case OP_BAUD : 
		brate = ch;
		/* check brate <= 15 */
		if (brate > 15) return(1); /* baud rate too large */
		/* return if unsupported baud rate */
		if (btab[brate] == -1) return(1);  
		outb(DUART_BASE+(3*8)+((chan)?0:0x40),0x80);
		/* ms baud */
		outb(DUART_BASE+(1*8)+((chan)?0:0x40),btab[brate]>>8); 
		/* ls baud */
		outb(DUART_BASE+(0*8)+((chan)?0:0x40),btab[brate]&0xff);
		/* mode: 2 stopbits, no parity, 8 bitsdata */
		outb(DUART_BASE+(3*8)+((chan)?0:0x40),0x03);
		break;
	case OP_CLKINIT : break;
	case OP_DELAY : return(0); break;
	case OP_BAUDRATES : /* list the supported baudrates */
		m = 1;
		for (i=v=0;btab[i] != 0;i++) {
			if (btab[i] != -1) v |= m;
			m <<= 1;
			}
		return(v); /* one bit per baudrate */
		break;
	}
return(0);
}