diff options
Diffstat (limited to 'hw/misc/mac_via.c')
| -rw-r--r-- | hw/misc/mac_via.c | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/hw/misc/mac_via.c b/hw/misc/mac_via.c index f2ccb12d64..9f9c2815d0 100644 --- a/hw/misc/mac_via.c +++ b/hw/misc/mac_via.c @@ -1001,6 +1001,8 @@ static void mos6522_q800_via1_write(void *opaque, hwaddr addr, uint64_t val, { MOS6522Q800VIA1State *v1s = MOS6522_Q800_VIA1(opaque); MOS6522State *ms = MOS6522(v1s); + int oldstate, state; + int oldsr = ms->sr; addr = (addr >> 9) & 0xf; @@ -1016,6 +1018,38 @@ static void mos6522_q800_via1_write(void *opaque, hwaddr addr, uint64_t val, v1s->last_b = ms->b; break; + + case VIA_REG_SR: + { + /* + * NetBSD assumes it can send its first ADB command after sending + * the ADB_BUSRESET command in ADB_STATE_NEW without changing the + * state back to ADB_STATE_IDLE first as detailed in the ADB + * protocol. + * + * Add a workaround to detect this condition at the start of ADB + * enumeration and send the next command written to SR after a + * ADB_BUSRESET onto the bus regardless, even if we don't detect a + * state transition to ADB_STATE_NEW. + * + * Note that in my tests the NetBSD state machine takes one ADB + * operation to recover which means the probe for an ADB device at + * address 1 always fails. However since the first device is at + * address 2 then this will work fine, without having to come up + * with a more complicated and invasive solution. + */ + oldstate = (v1s->last_b & VIA1B_vADB_StateMask) >> + VIA1B_vADB_StateShift; + state = (ms->b & VIA1B_vADB_StateMask) >> VIA1B_vADB_StateShift; + + if (oldstate == ADB_STATE_NEW && state == ADB_STATE_NEW && + (ms->acr & VIA1ACR_vShiftOut) && + oldsr == 0 /* ADB_BUSRESET */) { + trace_via1_adb_netbsd_enum_hack(); + adb_via_send(v1s, state, ms->sr); + } + } + break; } } |