1 files changed, 20 insertions, 14 deletions
diff --git a/drivers/serial.cc b/drivers/serial.cc
index 84dd4b0..22b8051 100644
--- a/drivers/serial.cc
+++ b/drivers/serial.cc
@@ -5,22 +5,18 @@
  * |dla|   | parity    | s | data  |
  */
 enum LineControlRegister : uint8_t {
-  // data bits
-  d5bit = 0b00000000,
+  d5bit = 0b00000000,  // data bits
   d6bit = 0b00000001,
   d7bit = 0b00000010,
   d8bit = 0b00000011,
-  // parity bits
-  none = 0b00000000,
+  none = 0b00000000,  // parity bits
   odd = 0b00001000,
   even = 0b00011000,
   mark = 0b00101000,
   space = 0b00111000,
-  // stop bits
-  s1bit = 0b00000000,
+  s1bit = 0b00000000,  // stop bits
   s2bit = 0b00000100,  // 1.5 for 5bit data; 2 otherwise
-  // divisor latch access bit
-  dlab = 0b10000000,
+  dlab = 0b10000000,   // divisor latch access bit
 };
 
 /* Line Status Register */
@@ -35,6 +31,10 @@ enum LineStatusRegister : uint8_t {
   ERRO = 0b10000000,  // impending error: see if there is an error with a word in the input buffer
 };
 
+// TODO InterruptControlRegister
+// TODO FifoControlRegister
+// TODO ModemControlRegister
+
 SerialPort::SerialPort() {
   /*
    * The serial controller (UART) has a baud rate of 115200 ticks per second; to limit the speed of the port set the
@@ -54,6 +54,16 @@ SerialPort::SerialPort() {
 
   port.write(0xc7, FifoControl);      // enable FIFO, clear, with 14-byte threshold
   port.write(0x0b, ModemControl);     // IRQ enabled, RTS/DSR set
+
+  // test serial port
+  port.write(0x1e, ModemControl);  // set in loopback mode
+  port.write(0xae);                // write 0xae to port
+  self_check_okay = (port.read() == 0xae);
+
+  // if not faulty, set in normal operation mode
+  if (self_check_okay) {
+    port.write(0x0f, ModemControl);
+  }
 }
 
 bool SerialPort::ready_read() {
@@ -61,9 +71,7 @@ bool SerialPort::ready_read() {
 }
 
 uint8_t SerialPort::read() {
-  while (!ready_read()) {
-    asm volatile("nop");
-  }
+  while (!ready_read()) asm volatile("nop");
   return port.read();
 }
 
@@ -72,9 +80,7 @@ bool SerialPort::ready_write() {
 }
 
 void SerialPort::write(char c) {
-  while (!ready_write()) {
-    asm volatile("nop");
-  }
+  while (!ready_write()) asm volatile("nop");
 
   switch (c) {
     case '\n':