Initial commit

kernel/drivers/serial.c

@@ -0,0 +1,56 @@
+//
+// Created by rick on 28-01-21.
+//
+
+#include "serial.h"
+#include <types.h>
+#include <drivers/ports.h>
+
+int serial_init() {
+    port_byte_out(PORT_SERIAL_0 + PORT_SERIAL_INTERRUPT, 0x00);    // Disable all interrupts
+    port_byte_out(PORT_SERIAL_0 + PORT_SERIAL_LINE_CONTROL, 0x80);    // Enable DLAB (set baud rate divisor)
+    port_byte_out(PORT_SERIAL_0 + PORT_SERIAL_DLAB_LSB, 0x03);    // Set divisor to 3 (lo byte) 38400 baud
+    port_byte_out(PORT_SERIAL_0 + PORT_SERIAL_DLAB_MSB, 0x00);    //                  (hi byte)
+    port_byte_out(PORT_SERIAL_0 + PORT_SERIAL_LINE_CONTROL, 0x03);    // 8 bits, no parity, one stop bit
+    port_byte_out(PORT_SERIAL_0 + PORT_SERIAL_INTERRUPT_ID_FIFO,
+                  0xC7);    // Enable FIFO, clear them, with 14-byte threshold
+    port_byte_out(PORT_SERIAL_0 + PORT_SERIAL_MODEM_CONTROL, 0x0B);    // IRQs enabled, RTS/DSR set
+    port_byte_out(PORT_SERIAL_0 + PORT_SERIAL_MODEM_CONTROL, 0x1E);    // Set in loopback mode, test the serial chip
+    port_byte_out(PORT_SERIAL_0 + PORT_SERIAL_DATA,
+                  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 (port_byte_in(PORT_SERIAL_0 + PORT_SERIAL_DATA) != 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)
+    port_byte_out(PORT_SERIAL_0 + PORT_SERIAL_MODEM_CONTROL, 0x0F);
+    return 0;
+}
+
+int is_transmit_empty() {
+    return port_byte_in(PORT_SERIAL_0 + PORT_SERIAL_LINE_STATUS) & 0x20;
+}
+
+void write_serial(char a) {
+    while (is_transmit_empty() == 0);
+
+    port_byte_out(PORT_SERIAL_0 + PORT_SERIAL_DATA, a);
+}
+
+void serial_kprint(char *msg) {
+    u32 i = 0;
+    while (1) {
+        char c = msg[i];
+        if (c == 0) {
+            break;
+        }
+        if (c == '\n') {
+            write_serial('\r');
+        }
+        write_serial(c);
+        i++;
+    }
+}