uart16550.c

umon bootloader source code, support mips cpu.

#include "config.h"
#include "uart16550.h"

/* Generic (hopefully) 16550 uart code for use as a MicroMonitor
 * console serial port driver.
 * 
 * The baud-rate divisor can be derived in one of two ways:
 * If BRD_115200 is defined, then this code assumes that the full
 * set of BRD_XXX definitions are defined (in config.h) and they
 * are used.  If BRD_115200 is not defined, then this driver assumes
 * the getUartDivisor() function is externally provided by the
 * port-specific code.
 * 
 * The base address of the UART used as the console port must be 
 * defined as CONSOLE_UART_BASE (also in config.h).
 *
 * Also, if the uart is configured in the memory map such that the
 * gap between registers is not 1, then set SIO_STEP (see uart16550.h)
 * to 2 or 4 appropriately. 
 */

#define CONSOLE(offset) *(volatile unsigned char *)(CONSOLE_UART_BASE+offset)

#ifdef MORE_GOTACHAR
extern void MORE_GOTACHAR();
#endif
#ifdef MORE_GETCHAR
extern void MORE_GETCHAR();
#endif
#ifdef MORE_PUTCHAR
extern void MORE_PUTCHAR();
#endif

/* Establish default initialization values that can be overridden
 * in config.h:
 */
#ifndef MCTL_DEFAULT
#define MCTL_DEFAULT	(SIO_MCTL_DTR | SIO_MCTL_RTS)
#endif
#ifndef FCTL_DEFAULT
#define FCTL_DEFAULT	(SIO_FCTL_FEN | SIO_FCTL_RXDC | SIO_FCTL_TXDC)
#endif
#ifndef SPR_DEFAULT
#define SPR_DEFAULT		0x00		// Clear scratchpad
#endif
#ifndef IEN_DEFAULT
#define IEN_DEFAULT		0x00		// Ints used
#endif
#ifndef LCTL_DEFAULT
#define LCTL_DEFAULT	SIO_LCTL_W8
#endif

/* getDlLsb():
 * Populate hi & lo, default to 9600...
 */
#ifdef BRD_115200
int
getUartDivisor(int baud, unsigned char *hi, unsigned char *lo)
{
	switch(baud) {
		case 115200:
			*lo = BRD_115200;
			break;
		case 57600:
			*lo = BRD_57600;
			break;
		case 38400:
			*lo = BRD_38400;
			break;
		case 19200:
			*lo = BRD_19200;
			break;
		case 9600:
			*lo = BRD_9600;
			break;
		default:
			return(-1);
	}
	*hi = 0;
	return(0);
}
#endif

int
ConsoleBaudSet(int baud)
{
	unsigned char	tmp, hi, lo;

	/* If either getDivisor returns -1 or both hi & lo are zero we
	 * return failure to indicate that the requested baud rate could
	 * not be established.
	 */
	if (getUartDivisor(baud,&hi,&lo) == -1)
		return(-1);
	if ((hi == 0) && (lo == 0))
		return(-1);

	tmp = CONSOLE(SIO_LCTL);	/* Save linectl reg */
	CONSOLE(SIO_LCTL) = SIO_LCTL_DLAB;
	CONSOLE(SIO_BAUDLO) = lo;	/* Set baud */
	CONSOLE(SIO_BAUDHI) = hi;
	CONSOLE(SIO_LCTL) = tmp; 	/* Restore linectl reg */
	return(0);
}


void
InitUART(int baud)
{
	unsigned char	tmp, hi, lo;

	getUartDivisor(baud,&hi,&lo);
	
	CONSOLE(SIO_LCTL) = SIO_LCTL_DLAB;
	CONSOLE(SIO_BAUDLO) = lo;			/* Set baud */
	CONSOLE(SIO_BAUDHI) = hi;
	CONSOLE(SIO_LCTL) = LCTL_DEFAULT;	/* 8-bits, no parity */
	CONSOLE(SIO_MCTL) = MCTL_DEFAULT;
	tmp = CONSOLE(SIO_LSTAT);			/* clear line stat */
	tmp = CONSOLE(SIO_RXD);				/* read receive buffer */
	CONSOLE(SIO_IEN) = IEN_DEFAULT;
	CONSOLE(SIO_FCTL) = FCTL_DEFAULT;
	CONSOLE(SIO_SPR) = SPR_DEFAULT;
}

int
target_console_empty(void)
{
	if (CONSOLE(SIO_LSTAT) & SIO_LSTAT_TRDY)
		return(0);
	return(1);
}

int
target_putchar(char c)
{
	while(!(CONSOLE(SIO_LSTAT) & SIO_LSTAT_TRDY));
	CONSOLE(SIO_TXD) = c;
#ifdef MORE_PUTCHAR
	MORE_PUTCHAR(c);
#endif
	return((int)c);
}

int
target_getchar(void)
{
	char c;

#ifdef MORE_GETCHAR
	if (MORE_GOTACHAR())
		c = MORE_GETCHAR();
	else
#endif
		c = CONSOLE(SIO_RXD);
	return((int)c);
}

int
target_gotachar(void)
{
	if (CONSOLE(SIO_LSTAT) & SIO_LSTAT_RRDY)
		return(1);
#ifdef MORE_GOTACHAR
	if (MORE_GOTACHAR())
		return(1);
#endif
	return(0);
}