PS/2 keyboard check availability

kernel/device/ps2/ps2_kb.c

@@ -15,10 +15,13 @@
 #include <sync/spin_lock.h>
 #include <sys/debug.h>
 #include <sys/smp.h>
+#include <sys/stall.h>
 
 #define KB_CTL_STATUS  0x64
 #define KB_DATA_IN_BUF 0x01
 #define KB_DATA        0x60
+#define KB_IDENTIFY    0xF2
+#define KB_ACK         0xFA
 
 #define PS2KB_RINGBUFFER_MAX 2048
 
@@ -225,7 +228,34 @@ static void ps2kb_set_typematic(uint8_t delay, uint8_t rate) {
   outb(KB_DATA, (delay << 5) | (rate & 0x1F));
 }
 
+static bool ps2kb_check(void) {
+  while (inb(KB_CTL_STATUS) & KB_DATA_IN_BUF)
+    inb(KB_DATA);
+
+  while (inb(KB_CTL_STATUS) & 0x02)
+    ;
+
+  outb(KB_DATA, KB_IDENTIFY);
+
+  for (int i = 0; i < 1000; i++) {
+    if (inb(KB_CTL_STATUS) & KB_DATA_IN_BUF) {
+      uint8_t response = inb(KB_DATA);
+      if (response == KB_ACK)
+        return true;
+    }
+
+    stall_ms(2);
+  }
+
+  return false;
+}
+
 DEFINE_DEVICE_INIT(ps2kb_init) {
+  if (!ps2kb_check()) {
+    DEBUG("PS/2 keyboard not detected!\n");
+    return false;
+  }
+
   ioapic_route_irq(INTR_PS2KB, 1, 0, thiscpu->lapic_id);
   irq_attach(&ps2kb_irq, NULL, INTR_PS2KB);