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.
Signed-off-by: Mark Cave-Ayland <mark.cave-ayl...@ilande.co.uk>
---
hw/misc/mac_via.c | 34 ++++++++++++++++++++++++++++++++++
hw/misc/trace-events | 1 +
2 files changed, 35 insertions(+)
diff --git a/hw/misc/mac_via.c b/hw/misc/mac_via.c
index 5d5334b0f6..564db8337e 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;
}
}
diff --git a/hw/misc/trace-events b/hw/misc/trace-events
index d3a9295d2f..7206bd5d93 100644
--- a/hw/misc/trace-events
+++ b/hw/misc/trace-events
@@ -249,6 +249,7 @@ via1_rtc_cmd_pram_sect_write(int sector, int offset, int
addr, int value) "secto
via1_adb_send(const char *state, uint8_t data, const char *vadbint) "state %s
data=0x%02x vADBInt=%s"
via1_adb_receive(const char *state, uint8_t data, const char *vadbint, int
status, int index, int size) "state %s data=0x%02x vADBInt=%s status=0x%x
index=%d size=%d"
via1_adb_poll(uint8_t data, const char *vadbint, int status, int index, int
size) "data=0x%02x vADBInt=%s status=0x%x index=%d size=%d"
+via1_adb_netbsd_enum_hack(void) "using NetBSD enum hack"
via1_auxmode(int mode) "setting auxmode to %d"
via1_timer_hack_state(int state) "setting timer_hack_state to %d"
--
2.30.2
