Serial IRQ function

Co-Authored-By: Miran Grča <oubattler@gmail.com>

src/device/serial.c

@@ -15,7 +15,7 @@
  * Authors: Miran Grca, <mgrca8@gmail.com>
  *          Fred N. van Kempen, <decwiz@yahoo.com>
  *
- *          Copyright 2016-2020 Miran Grca.
+ *          Copyright 2016-2025 Miran Grca.
  *          Copyright 2017-2020 Fred N. van Kempen.
  */
 #include <stdarg.h>
@@ -782,6 +782,20 @@ serial_setup(serial_t *dev, uint16_t addr, uint8_t irq)
     dev->irq = irq;
 }
 
+void
+serial_irq(serial_t *dev, const uint8_t irq)
+{
+    if (dev == NULL)
+        return;
+
+    if (com_ports[dev->inst].enabled)
+        dev->irq = irq;
+    else
+        dev->irq = 0xff;
+
+    serial_log("Port %i IRQ = %02X\n", dev->inst, irq);
+}
+
 static void
 serial_rcvr_d_empty_evt(void *priv)
 {