mcf5xxx_uart.c

motorola 针对coldfire 5275 评估板的Dbug bootloader源程序

/*
 * File:        mcf5xxx_uart.c
 * Purpose:     Provide common ColdFire UART initialization
 *
 * Notes:       This file provides an initialization routine to enable
 *              the specified UART to be used for as a terminal in 
 *              dBUG. The settings are 8 bits, no parity, 1 stop
 *              bit, polled mode (no interrupts).
 */

#include "src/include/dbug.h"

/********************************************************************/
/*
 * Initialize the UART for 8N1 operation, interrupts disabled, and
 * no hardware flow-control
 *
 * Parameters:
 *  uartch      UART channel to initialize
 *  sysclk      Reference Clock in MHz (used to calculate baud)
 *  baud        UART baud rate
 */
void 
mcf5xxx_uart_init (int uartch, int refclk, int baud)
{
    register uint16 ubgs;

    /* Reset Transmitter */
    MCF_UART_UCR(uartch) = MCF_UART_UCR_RESET_TX;

    /* Reset Receiver */
    MCF_UART_UCR(uartch) = MCF_UART_UCR_RESET_RX;

    /* Reset Mode Register */
    MCF_UART_UCR(uartch) = MCF_UART_UCR_RESET_MR;

    /* No parity, 8-bits per character */
    MCF_UART_UMR(uartch) = (0
        | MCF_UART_UMR_PM_NONE
        | MCF_UART_UMR_BC_8);

    /* No echo or loopback, 1 stop bit */
    MCF_UART_UMR(uartch) = (0
        | MCF_UART_UMR_CM_NORMAL
        | MCF_UART_UMR_SB_STOP_BITS_1);

    /* Set Rx and Tx baud by timer */
    MCF_UART_UCSR(uartch) = (0
        | MCF_UART_UCSR_RCS_SYS_CLK
        | MCF_UART_UCSR_TCS_SYS_CLK);

    /* Mask all UART interrupts */
    MCF_UART_UIMR(uartch) = 0;
                 
    /* Calculate baud settings */
    ubgs = (uint16)((refclk*1000000)/(baud * 32));

    MCF_UART_UBG1(uartch) = (uint8)((ubgs & 0xFF00) >> 8);
    MCF_UART_UBG2(uartch) = (uint8)(ubgs & 0x00FF);

    /* Enable receiver and transmitter */
    MCF_UART_UCR(uartch) = (0
        | MCF_UART_UCR_TX_ENABLED
        | MCF_UART_UCR_RX_ENABLED);
}
/********************************************************************/