Initial commit

src/drivers/serial.c

@@ -0,0 +1,76 @@
+#include "../sys/acpi.h"
+#include "../hal/ioapic.h"
+#include <io.h>
+#include <stdio.h>
+
+#define COM1            0x3F8
+
+#define LINE_CTRL_REG   0x3
+#define LINE_STAT_REG   0x5
+#define INT_ENABLE_REG  0x1
+#define MDM_CTRL_REG    0x4
+
+#define DIVISOR         0x12     // We want a baud rate of 9600, so the divisor here is 12
+
+bool serial_enabled = false;
+
+void serial_init(){
+
+    /* Disable interrupts */
+    outb(COM1 + INT_ENABLE_REG, 0);
+
+    /* Set the DLAB bit */
+    outb(COM1 + LINE_CTRL_REG, (1 << 7));
+
+    /* Send least significant byte of divisor */
+    outb(COM1 + 1, 0);
+
+    /* Send most significant byte of divisor */
+    outb(COM1, 12);
+
+    /* Clear the DLAB bit */
+    outb(COM1 + LINE_CTRL_REG, (0 << 7));
+
+    /* Set the character length to 8 bits, parity to none and stop bit to 1 */
+    outb(COM1 + LINE_CTRL_REG, 0b00000011);
+
+    /* Set DTR, RTS and enables IRQ */
+    outb(COM1 + MDM_CTRL_REG, 0b00001101);
+
+    /* Set loopback testing mode to see if UART werks */
+    outb(COM1 + MDM_CTRL_REG, 0b00011110);
+
+    outb(COM1, 0xAE);
+
+    if(inb(COM1) != 0xAE){
+        klog(LOG_WARN, __func__, "Serial controller failed test, serial output will not work");
+        return;
+    }
+
+    /* Disable loopback and set DTR bit */
+    outb(COM1 + MDM_CTRL_REG, 0b00001111);
+
+    serial_enabled = true;
+
+}
+
+uint8_t serial_read(){
+    while((inb(COM1 + LINE_STAT_REG) & 0x1) == 0){ asm("nop"); }
+
+    return inb(COM1);
+}
+
+void serial_write(uint8_t data){
+    while((inb(COM1 + LINE_STAT_REG) & (1 << 5)) == 0){ asm("nop"); }
+    
+    outb(COM1, data);
+}
+
+void serial_print(char *str){
+    uint64_t i = 0;
+    while (str[i] != '\0') {
+        serial_write(str[i]);
+        i++;
+    }
+}
+