xref: /nrf52832-nimble/rt-thread/libcpu/arm/s3c44b0/serial.c (revision 104654410c56c573564690304ae786df310c91fc)

/*
 * Copyright (c) 2006-2018, RT-Thread Development Team
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Change Logs:
 * Date           Author       Notes
 * 2006-09-06     XuXinming    first version
 * 2006-09-20     Bernard      clean code according code style
 */

#include <rtthread.h>
#include <rthw.h>

#include "s3c44b0.h"

void rt_serial_init(void);
void rt_console_puts(const char* str);
void rt_serial_putc(const char c);

#define	USTAT_RCV_READY		0x01	/* receive data ready */
#define	USTAT_TXB_EMPTY		0x02	/* tx buffer empty */

rt_inline void serial_flush_input(void)
{
	volatile unsigned int tmp;

	/* keep on reading as long as the receiver is not empty */
	while(UTRSTAT0 & USTAT_RCV_READY) tmp = URXH0;
}

rt_inline void serial_flush_output(void)
{
	/* wait until the transmitter is no longer busy */
	while(!(UTRSTAT0 & USTAT_TXB_EMPTY)) ;
}

/**
 * @addtogroup S3C44B0
 */
/*@{*/

/**
 * This function is used to display a string on console, normally, it's
 * invoked by rt_kprintf
 *
 * @param str the displayed string
 */
void rt_console_puts(const char* str)
{
	while (*str)
	{
		rt_serial_putc (*str++);
	}
}

/**
 * This function initializes serial
 */
void rt_serial_init()
{
	rt_uint32_t divisor = 0;

	divisor = 0x20;

	serial_flush_output();
	serial_flush_input();

	/* UART interrupt off */
	UCON0 	= 0;
	/* FIFO disable */
	UFCON0	=0x0;
	UMCON0	=0x0;
	/* set baudrate */
 	UBRDIV0 = divisor;

	/* word length=8bit, stop bit = 1, no parity, use external clock */
	ULCON0 	= 0x03|0x00|0x00;

 	UCON0 	= 0x5;
}

/**
 * This function read a character from serial without interrupt enable mode
 *
 * @return the read char
 */
char rt_serial_getc()
{
	while ((UTRSTAT0 & USTAT_RCV_READY) == 0);

	return URXH0;
}

/**
 * This function will write a character to serial without interrupt enable mode
 *
 * @param c the char to write
 */
void rt_serial_putc(const char c)
{
	/*
		to be polite with serial console add a line feed
		to the carriage return character
	*/
	if (c=='\n')rt_serial_putc('\r');

	/* wait for room in the transmit FIFO */
	while(!(UTRSTAT0 & USTAT_TXB_EMPTY));

	UTXH0 = (rt_uint8_t)c;
}

/*@}*/