s3c6410_uart初始化及读写

参考：

1）《USER'S MANUAL-S3C6410X》第31章 UART

2）u-boot uart初始化及读写：u-boot-x.x.x/board/samsumg/smdk6410/lowlevel_init.S

   　　　　　　　　　　　　 u-boot-x.x.x/cpu/s3c64xx/serial.c

3) 内核串口驱动：linux-x.x.x/driver/tty/serial/s3c6400.c samsung.c serial_core.c

代码：

uart.c

#include "uart.h"

#define GPACON        (*((volatile unsigned long *)0x7f008000))

#define ULCON0        (*((volatile unsigned long *)0x7f005000))
#define UCON0        (*((volatile unsigned long *)0x7f005004))
#define UFCON0        (*((volatile unsigned long *)0x7f005008))
#define UMCON0        (*((volatile unsigned long *)0x7f00500c))
#define UTRSTAT0    (*((volatile unsigned long *)0x7f005010))
#define UERSTAT0    (*((volatile unsigned long *)0x7f005014))
#define UFSTAT0        (*((volatile unsigned long *)0x7f005018))
#define UMSTAT0        (*((volatile unsigned long *)0x7f00501c))
#define UTXH0        (*((volatile unsigned long *)0x7f005020))
#define URXH0        (*((volatile unsigned long *)0x7f005024))
#define UBRDIV0        (*((volatile unsigned long *)0x7f005028))
#define UDIVSLOT0    (*((volatile unsigned long *)0x7f00502c))
#define UINTP0        (*((volatile unsigned long *)0x7f005030))
#define UINTSP0        (*((volatile unsigned long *)0x7f005034))
#define UINTM0        (*((volatile unsigned long *)0x7f005038))

void uart0_init(void)
{
    GPACON &= ~0xff;
    GPACON |= 0X22;
    
    ULCON0 = 0x03; //data frame: 8n1
    /*
    clk: pclk
    tx int type: level
    rx int type: pulse
    rx err int enable
    tx/rx mode: interrupt or polling 
    */
    UCON0 = 0x245; 
    UFCON0 = 0x00; //disable fifo;
    UMCON0 = 0X00; //disable auto flow control(AFC)
    /*
    DIV_VAL = UBRDIV + (num of 1's in UDIVSLOT)/16
    DIV_VAL = (PCLK/(bps*16))-1 = (66000000/115200)-1=34.8
    UBRDIV = 34;
    num of 1's in UDIVSLOT = 13; 
    */
    UBRDIV0 = 0x22;
    UDIVSLOT0 = 0x1fff;
}

int uart0_getc(void)
{
    while (!(UTRSTAT0 & 0x1));
    return (URXH0 & 0xff); 
}

void uart0_putc(const char c)
{
    while (!(UTRSTAT0 & 0x2));
    UTXH0 = c;
    if (c == '
')
    {
        uart0_putc('
');
    }
}

void uart0_puts(const char *s)
{
    while (*s)
    {
        uart0_putc(*s++);
    }
}