pckbd: add QEMU interface comment for I8042 device

This describes the I8042 device interface implemented within QEMU.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Message-Id: <20220624134109.881989-54-mark.cave-ayland@ilande.co.uk>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

diff --git a/include/hw/input/i8042.h b/include/hw/input/i8042.h
index d4747b62b8200403ed261d937838e38d527b19e9..ca933d8e1b52432366f5cd2cbbabaa8a597dda02 100644 (file)
--- a/include/hw/input/i8042.h
+++ b/include/hw/input/i8042.h
@@ -39,6 +39,16 @@ typedef struct KBDState {
     hwaddr mask;
 } KBDState;
 
+/*
+ * QEMU interface:
+ * + Named GPIO input "ps2-kbd-input-irq": set to 1 if the downstream PS2
+ *   keyboard device has asserted its irq
+ * + Named GPIO input "ps2-mouse-input-irq": set to 1 if the downstream PS2
+ *   mouse device has asserted its irq
+ * + Named GPIO output "a20": A20 line for x86 PCs
+ * + Unnamed GPIO output 0-1: i8042 output irqs for keyboard (0) or mouse (1)
+ */
+
 #define TYPE_I8042 "i8042"
 OBJECT_DECLARE_SIMPLE_TYPE(ISAKBDState, I8042)