Squash commits for public release

boot/x86_64/prekernel/drivers/uart.c

@@ -0,0 +1,43 @@
+#include "uart.h"
+#include "port.h"
+
+static int _uart_setup_impl(int port)
+{
+    port_write8(port + 1, 0x00);
+    port_write8(port + 3, 0x80);
+    port_write8(port + 0, 0x03);
+    port_write8(port + 1, 0x00);
+    port_write8(port + 3, 0x03);
+    port_write8(port + 2, 0xC7);
+    port_write8(port + 4, 0x0B);
+    return 0;
+}
+
+void uart_init()
+{
+    _uart_setup_impl(COM1);
+}
+
+static inline bool _uart_is_free_in(int port)
+{
+    return port_read8(port + 5) & 0x01;
+}
+
+static inline bool _uart_is_free_out(int port)
+{
+    return port_read8(port + 5) & 0x20;
+}
+
+int uart_write(uint8_t data)
+{
+    while (!_uart_is_free_out(COM1)) { }
+    port_write8(COM1, data);
+    return 0;
+}
+
+int uart_read(uint8_t* data)
+{
+    while (!_uart_is_free_out(COM1)) { }
+    *data = port_read8(COM1);
+    return 0;
+}