diff options
Diffstat (limited to 'hw/pckbd.c')
| -rw-r--r-- | hw/pckbd.c | 23 |
1 files changed, 20 insertions, 3 deletions
diff --git a/hw/pckbd.c b/hw/pckbd.c index 0533b1d9e3..6e4e4062ad 100644 --- a/hw/pckbd.c +++ b/hw/pckbd.c @@ -56,7 +56,9 @@ #define KBD_CCMD_WRITE_MOUSE 0xD4 /* Write the following byte to the mouse */ #define KBD_CCMD_DISABLE_A20 0xDD /* HP vectra only ? */ #define KBD_CCMD_ENABLE_A20 0xDF /* HP vectra only ? */ -#define KBD_CCMD_RESET 0xFE +#define KBD_CCMD_PULSE_BITS_3_0 0xF0 /* Pulse bits 3-0 of the output port P2. */ +#define KBD_CCMD_RESET 0xFE /* Pulse bit 0 of the output port P2 = CPU reset. */ +#define KBD_CCMD_NO_OP 0xFF /* Pulse no bits of the output port P2. */ /* Keyboard Commands */ #define KBD_CMD_SET_LEDS 0xED /* Set keyboard leds */ @@ -238,6 +240,21 @@ static void kbd_write_command(void *opaque, uint32_t addr, uint32_t val) KBDState *s = opaque; DPRINTF("kbd: write cmd=0x%02x\n", val); + + /* Bits 3-0 of the output port P2 of the keyboard controller may be pulsed + * low for approximately 6 micro seconds. Bits 3-0 of the KBD_CCMD_PULSE + * command specify the output port bits to be pulsed. + * 0: Bit should be pulsed. 1: Bit should not be modified. + * The only useful version of this command is pulsing bit 0, + * which does a CPU reset. + */ + if((val & KBD_CCMD_PULSE_BITS_3_0) == KBD_CCMD_PULSE_BITS_3_0) { + if(!(val & 1)) + val = KBD_CCMD_RESET; + else + val = KBD_CCMD_NO_OP; + } + switch(val) { case KBD_CCMD_READ_MODE: kbd_queue(s, s->mode, 0); @@ -294,8 +311,8 @@ static void kbd_write_command(void *opaque, uint32_t addr, uint32_t val) case KBD_CCMD_RESET: qemu_system_reset_request(); break; - case 0xff: - /* ignore that - I don't know what is its use */ + case KBD_CCMD_NO_OP: + /* ignore that */ break; default: fprintf(stderr, "qemu: unsupported keyboard cmd=0x%02x\n", val); |