BarinkOS/source/kernel/serial.h

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C
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#pragma once
#include "tty/kterm.h"
#include "drivers/IO/io.h"
#define PORT 0x3f8
static int init_serial() {
#ifdef __VERBOSE__
printf("Init Serial\n");
#endif
outb(PORT + 1, 0x00); // Disable all interrupts
outb(PORT + 3, 0x80); // Enable DLAB (set baud rate divisor)
outb(PORT + 0, 0x03); // Set divisor to 3 (lo byte) 38400 baud
outb(PORT + 1, 0x00); // (hi byte)
outb(PORT + 3, 0x03); // 8 bits, no parity, one stop bit
outb(PORT + 2, 0xC7); // Enable FIFO, clear them, with 14-byte threshold
outb(PORT + 4, 0x0B); // IRQs enabled, RTS/DSR set
outb(PORT + 4, 0x1E); // Set in loopback mode, test the serial chip
outb(PORT + 0, 0xAE); // Test serial chip (send byte 0xAE and check if serial returns same byte)
// Check if serial is faulty (i.e: not same byte as sent)
if(inb(PORT + 0) != 0xAE) {
return 1;
}
// If serial is not faulty set it in normal operation mode
// (not-loopback with IRQs enabled and OUT#1 and OUT#2 bits enabled)
outb(PORT + 4, 0x0F);
return 0;
}
inline int is_transmit_empty() {
return inb(PORT + 5) & 0x20;
}
inline void write_serial(char a) {
while (is_transmit_empty() == 0);
outb(PORT,a);
}
inline int serial_received() {
return inb(PORT + 5) & 1;
}
inline char read_serial() {
while (serial_received() == 0);
return inb(PORT);
}
inline void print_serial(const char* string ){
for(size_t i = 0; i < strlen(string); i ++){
write_serial(string[i]);
}
}
inline void test_serial(){
/** Serial test **/
kterm_writestring("Writing to COM1 serial port:");
init_serial();
write_serial('A');
write_serial('B');
write_serial('C');
write_serial('D');
write_serial('E');
char Character_received = read_serial();
kterm_writestring("\n");
kterm_writestring("received from COM 1: \n");
kterm_put(Character_received);
kterm_writestring("\n");
}