From 1fb05a21e8ae570c4c3902ae5fe6635df029bcda Mon Sep 17 00:00:00 2001
From: dzwdz
Date: Sat, 2 Oct 2021 19:32:41 +0000
Subject: serial: implement a selftest
---
src/kernel/arch/i386/tty/serial.c | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)
(limited to 'src/kernel/arch')
diff --git a/src/kernel/arch/i386/tty/serial.c b/src/kernel/arch/i386/tty/serial.c
index b3f1d9d..6ddc05b 100644
--- a/src/kernel/arch/i386/tty/serial.c
+++ b/src/kernel/arch/i386/tty/serial.c
@@ -1,9 +1,17 @@
-#include <kernel/arch/i386/tty/serial.h>
#include <kernel/arch/i386/port_io.h>
+#include <kernel/arch/i386/tty/serial.h>
+#include <kernel/panic.h>
#include <stdint.h>
static const int COM1 = 0x3f8;
+static void serial_selftest(void) {
+ char b = 0x69;
+ port_outb(COM1 + 4, 0b00011110); // enable loopback mode
+ port_outb(COM1, b);
+ assert(port_inb(COM1) == b);
+}
+
void serial_init(void) {
// see https://www.sci.muni.cz/docs/pc/serport.txt
@@ -16,11 +24,10 @@ void serial_init(void) {
port_outb(COM1 + 3, 0b00000011); // 8 bits, no parity, one stop bit
port_outb(COM1 + 2, 0b11000111); // enable FIFO with 14-bit trigger level (???)
- port_outb(COM1 + 4, 0b00001111); // enable everything in the MCR
- /* the example on the OSDEV wiki does a selftest of the serial connection
- * i don't really see the point as long as i'm not using it for input?
- * if i start using serial for input, TODO selftest */
+ serial_selftest();
+
+ port_outb(COM1 + 4, 0b00001111); // enable everything in the MCR
}
static void serial_putchar(char c) {
--
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