--- /dev/null
+/* SPDX-License-Identifier: BSD-3-Clause */
+/* Copyright (c) 2025, Unikraft GmbH and The Unikraft Authors.
+ * Licensed under the BSD-3-Clause License (the "License").
+ * You may not use this file except in compliance with the License.
+ */
+
+#include <uk/bitops.h>
+#include <uk/event.h>
+#include <uk/init.h>
+#include <uk/intctlr.h>
+#include <x86/delay.h>
+
+/* Default legacy IRQ for the PS/2 keyboard */
+#define PIC1_IRQ_KBD 0x1
+
+#define I8042_DATA_REG 0x60
+
+#define I8042_STATUS_REG 0x64
+#define I8042_STATUS_RECV_FULL UK_BIT(0)
+#define I8042_STATUS_SEND_FULL UK_BIT(1)
+
+#define I8042_CMD_REG 0x64
+#define I8042_CMD_READ_CFG 0x20
+#define I8042_CMD_WRITE_CFG 0x60
+#define I8042_CMD_DIS_KBD 0xAD
+#define I8042_CMD_EN_KBD 0xAE
+
+#define I8042_CFG_REG_EN_KBD_IRQ UK_BIT(0)
+#define I8042_CFG_REG_DIS_KBD_CLK UK_BIT(4)
+
+/* ACPI scan code set - enough for Firecracker "Send CtrlAltDelete" */
+#define I8042_KEY_CTRL 0x0014
+#define I8042_KEY_ALT 0x0011
+#define I8042_KEY_DEL 0xE071
+
+static __u8 lctrl_pressed;
+static __u8 lalt_pressed;
+
+UK_EVENT(UKPLAT_SHUTDOWN_EVENT);
+
+static int kbd_ps2_irq_handler(void *arg __unused)
+{
+ /* Read received scan code (ACPI scan code set) */
+ __u16 sc;
+
+ /* If not a key pressed, probably another event on first PS/2 port */
+ if (!(inb(I8042_STATUS_REG) & I8042_STATUS_RECV_FULL))
+ return 0;
+
+ sc = (inb(I8042_DATA_REG) << 8) + inb(I8042_DATA_REG);
+
+ switch (sc) {
+ /* TODO: This is dumbed down, enough for Firecracker shutdown. In
+ * reality the scan codes will most likely not conveniently come one
+ * after another.
+ */
+ case ((I8042_KEY_CTRL << 8) | I8042_KEY_ALT):
+ lctrl_pressed = 1;
+ lalt_pressed = 1;
+
+ break;
+ case I8042_KEY_DEL:
+ if (!(lctrl_pressed && lalt_pressed))
+ break;
+
+ uk_raise_event(UKPLAT_SHUTDOWN_EVENT, (void *)UKPLAT_HALT);
+
+ break;
+ }
+
+ return 0;
+}
+
+/* Quick, dumbed down, initialization for PS/2 keyboard */
+static int kbd_ps2_probe(struct uk_init_ctx *ictx __unused)
+{
+ int counter = 0;
+ __u8 cfg;
+ int rc;
+
+ /* In Firecracker's words:
+ * "A i8042 PS/2 controller that emulates just enough to shutdown the
+ * machine."
+ * See Firecracker's 80128ea61b30 ("New API action: SendCtrlAltDel").
+ */
+
+ /* PS/2 Keyboard is on first port. Just enable it. */
+ outb(I8042_CMD_REG, I8042_CMD_EN_KBD);
+
+ /* Send read current configuration register command */
+ outb(I8042_CMD_REG, I8042_CMD_READ_CFG);
+
+ /* Wait for response byte by checking status bit of receive buffer.
+ * Try for 5 times, but it should work the first time usually.
+ */
+ while (!(inb(I8042_STATUS_REG) & I8042_STATUS_RECV_FULL)) {
+ if (unlikely(counter >= 5)) {
+ outb(I8042_CMD_REG, I8042_CMD_DIS_KBD);
+ uk_pr_err("PS/2 Controller unresponsie\n");
+ return -ENODEV;
+ }
+
+ /* We are advised to wait 50ms if the controller hasn't
+ * responded yet.
+ */
+ udelay(50);
+ counter++;
+ }
+
+ /* Read the configuration register */
+ cfg = inb(I8042_DATA_REG);
+
+ /* This shouldn't even be needed in a virtualized environment, e.g.
+ * on Firecracker the above sending of I8042_CMD_EN_KBD would be enough.
+ */
+ cfg |= I8042_CFG_REG_EN_KBD_IRQ;
+ cfg &= ~I8042_CFG_REG_DIS_KBD_CLK;
+
+ /* Send write current configuration register command */
+ outb(I8042_CMD_REG, I8042_CMD_WRITE_CFG);
+
+ /* Send the new configuration register value */
+ outb(I8042_DATA_REG, cfg);
+
+ /* TODO: Legacy wired to Master PIC IRQ 1, with I/O-APIC this is likely
+ * rewired so check ACPI MADT Interrupt Source Override.
+ */
+ rc = uk_intctlr_irq_register(PIC1_IRQ_KBD, kbd_ps2_irq_handler, NULL);
+ if (unlikely(rc)) {
+ uk_pr_err("Failed to register PS/2 Keryboard IRQ\n");
+ return rc;
+ }
+
+ return 0;
+}
+
+uk_early_initcall(kbd_ps2_probe, 0x0);
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