ns16550.c

ATMEL公司的AT91RM9200芯片在嵌入式系统中应用非常多

/*
 * COM1 NS16550 support
 * originally from linux source (arch/ppc/boot/ns16550.c)
 * modified to use CFG_ISA_MEM and new defines
 */

#include <config.h>
#include "ns16550.h"

typedef struct NS16550 *NS16550_t;

const NS16550_t COM_PORTS[] = { (NS16550_t) ((CFG_EUMB_ADDR) + 0x4500), (NS16550_t) ((CFG_EUMB_ADDR) + 0x4600)};

volatile struct NS16550 *
NS16550_init(int chan, int baud_divisor)
{
 volatile struct NS16550 *com_port;
 com_port = (struct NS16550 *) COM_PORTS[chan];
 com_port->ier = 0x00;
 com_port->lcr = LCR_BKSE;              /* Access baud rate */
 com_port->dll = baud_divisor & 0xff;   /* 9600 baud */
 com_port->dlm = (baud_divisor >> 8) & 0xff;
 com_port->lcr = LCR_8N1;               /* 8 data, 1 stop, no parity */
 com_port->mcr = MCR_RTS;     /* RTS/DTR */
 com_port->fcr = FCR_FIFO_EN | FCR_RXSR | FCR_TXSR;                  /* Clear & enable FIFOs */
return (com_port);
}

void
NS16550_reinit(volatile struct NS16550 *com_port, int baud_divisor)
{
 com_port->ier = 0x00;
 com_port->lcr = LCR_BKSE;              /* Access baud rate */
 com_port->dll = baud_divisor & 0xff;   /* 9600 baud */
 com_port->dlm = (baud_divisor >> 8) & 0xff;
 com_port->lcr = LCR_8N1;               /* 8 data, 1 stop, no parity */
 com_port->mcr = MCR_RTS;     /* RTS/DTR */
 com_port->fcr = FCR_FIFO_EN | FCR_RXSR | FCR_TXSR;                  /* Clear & enable FIFOs */
}

void NS16550_putc(volatile struct NS16550 *com_port, unsigned char c)
{
 while ((com_port->lsr & LSR_THRE) == 0) ;
 com_port->thr = c;
}

unsigned char
NS16550_getc(volatile struct NS16550 *com_port)
{
 while ((com_port->lsr & LSR_DR) == 0) ;
 return (com_port->rbr);
}

int NS16550_tstc(volatile struct NS16550 *com_port)
{
 return ((com_port->lsr & LSR_DR) != 0);
}