sercons.c

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#include <stdbool.h>
#include <stdint.h>
 
#include <sys/kassert.h>
#include <sys/irq.h>
 
#include "ioport.h"
#include "sercons.h"
 
#define COM1_BASE               0x3F8
#define COM2_BASE               0x2F8
#define COM3_BASE               0x3E8
#define COM4_BASE               0x2E8
 
#define COM1_IRQ                4
#define COM2_IRQ                3
#define COM3_IRQ                4
#define COM4_IRQ                3
 
// Inputs
#define UART_OFFSET_DATA        0   /* Data Register */
#define UART_OFFSET_IER         1   /* Interrupt Enable Register */
#define UART_OFFSET_IIR         2   /* Interrupt Identification & FIFO Control */
#define UART_OFFSET_LCR         3   /* Line Control Register */
#define UART_LCR_DLAB           0x80
#define UART_LCR_8N1            0x03
#define UART_OFFSET_MCR         4   /* Modem Control Register */
#define UART_OFFSET_LSR         5   /* Line Status Register */
#define UART_OFFSET_MSR         6   /* Modem Status Register */
#define UART_OFFSET_SR          7   /* Scratch Register */
 
#define UART_OFFSET_DIVLO       0   /* Divisors DLAB == 1 */
#define UART_OFFSET_DIVHI       1
 
static IRQHandler handler;
static uint16_t base;
static uint8_t irq;
 
void Serial_Init(void)
{
    base = COM1_BASE;
    irq = COM1_IRQ;
 
    // Disable interrupts
    outb(base + UART_OFFSET_IER, 0);
 
    // Enable DLAB
    outb(base + UART_OFFSET_LCR, UART_LCR_DLAB);
    outb(base + UART_OFFSET_DIVLO, 1); // 115200 Baud
    outb(base + UART_OFFSET_DIVLO, 0);
    outb(base + UART_OFFSET_LCR, UART_LCR_8N1);
 
    // Enable interrupts
    outb(base + UART_OFFSET_IIR, 0xC7);
    outb(base + UART_OFFSET_MCR, 0x0B);
}
 
void Serial_LateInit(void)
{
    handler.irq = irq;
    handler.cb = &Serial_Interrupt;
    handler.arg = NULL;
 
    IRQ_Register(irq, &handler);
}
 
void Serial_Interrupt(void *arg)
{
    kprintf("Serial interrupt!\n");
}
 
bool Serial_HasData()
{
    return (inb(base + UART_OFFSET_LSR) & 0x01) != 0;
}
 
char Serial_Getc()
{
    while ((inb(base + UART_OFFSET_LSR) & 0x01) == 0)
    {
        // Timeout!
    }
    return inb(base + UART_OFFSET_DATA);
}
 
void Serial_Putc(char ch)
{
    while ((inb(base + UART_OFFSET_LSR) & 0x20) == 0)
    {
        // Timeout!
    }
    outb(base + UART_OFFSET_DATA, ch);
 
    if (ch == '\b') {
        Serial_Putc(0x1B);
        Serial_Putc('[');
        Serial_Putc('P');
    }
}
 
void Serial_Puts(const char *str)
{
    const char *p = str;
    while (*p != '\0')
        Serial_Putc(*p++);
}