hw/m68k: implement ADB bus support for via

VIA needs to be able to poll the ADB interface and to read/write data
from/to the bus.

This patch adds functions allowing that.

Co-developed-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Hervé Poussineau <hpoussin@reactos.org>
Reviewed-by: Thomas Huth <huth@tuxfamily.org>
Message-Id: <20191026164546.30020-7-laurent@vivier.eu>

2 files changed, 198 insertions, 0 deletions

diff --git a/hw/misc/Kconfig b/hw/misc/Kconfig
index 18a5dc9..2164646 100644
--- a/hw/misc/Kconfig
+++ b/hw/misc/Kconfig
@@ -123,5 +123,6 @@ config UNIMP
 config MAC_VIA
     bool
     select MOS6522
+    select ADB
 
 source macio/Kconfig
diff --git a/hw/misc/mac_via.c b/hw/misc/mac_via.c
index d2da8b8..f3f130a 100644
--- a/hw/misc/mac_via.c
+++ b/hw/misc/mac_via.c
@@ -264,10 +264,16 @@
  * Table 19-10 ADB transaction states
  */
 
+#define ADB_STATE_NEW       0
+#define ADB_STATE_EVEN      1
+#define ADB_STATE_ODD       2
+#define ADB_STATE_IDLE      3
+
 #define VIA1B_vADB_StateMask    (VIA1B_vADBS1 | VIA1B_vADBS2)
 #define VIA1B_vADB_StateShift   4
 
 #define VIA_TIMER_FREQ (783360)
+#define VIA_ADB_POLL_FREQ 50 /* XXX: not real */
 
 /* VIA returns time offset from Jan 1, 1904, not 1970 */
 #define RTC_OFFSET 2082844800
@@ -472,6 +478,181 @@ static void via1_rtc_update(MacVIAState *m)
     }
 }
 
+static int adb_via_poll(MacVIAState *s, int state, uint8_t *data)
+{
+    if (state != ADB_STATE_IDLE) {
+        return 0;
+    }
+
+    if (s->adb_data_in_size < s->adb_data_in_index) {
+        return 0;
+    }
+
+    if (s->adb_data_out_index != 0) {
+        return 0;
+    }
+
+    s->adb_data_in_index = 0;
+    s->adb_data_out_index = 0;
+    s->adb_data_in_size = adb_poll(&s->adb_bus, s->adb_data_in, 0xffff);
+
+    if (s->adb_data_in_size) {
+        *data = s->adb_data_in[s->adb_data_in_index++];
+        qemu_irq_raise(s->adb_data_ready);
+    }
+
+    return s->adb_data_in_size;
+}
+
+static int adb_via_send(MacVIAState *s, int state, uint8_t data)
+{
+    switch (state) {
+    case ADB_STATE_NEW:
+        s->adb_data_out_index = 0;
+        break;
+    case ADB_STATE_EVEN:
+        if ((s->adb_data_out_index & 1) == 0) {
+            return 0;
+        }
+        break;
+    case ADB_STATE_ODD:
+        if (s->adb_data_out_index & 1) {
+            return 0;
+        }
+        break;
+    case ADB_STATE_IDLE:
+        return 0;
+    }
+
+    assert(s->adb_data_out_index < sizeof(s->adb_data_out) - 1);
+
+    s->adb_data_out[s->adb_data_out_index++] = data;
+    qemu_irq_raise(s->adb_data_ready);
+    return 1;
+}
+
+static int adb_via_receive(MacVIAState *s, int state, uint8_t *data)
+{
+    switch (state) {
+    case ADB_STATE_NEW:
+        return 0;
+
+    case ADB_STATE_EVEN:
+        if (s->adb_data_in_size <= 0) {
+            qemu_irq_raise(s->adb_data_ready);
+            return 0;
+        }
+
+        if (s->adb_data_in_index >= s->adb_data_in_size) {
+            *data = 0;
+            qemu_irq_raise(s->adb_data_ready);
+            return 1;
+        }
+
+        if ((s->adb_data_in_index & 1) == 0) {
+            return 0;
+        }
+
+        break;
+
+    case ADB_STATE_ODD:
+        if (s->adb_data_in_size <= 0) {
+            qemu_irq_raise(s->adb_data_ready);
+            return 0;
+        }
+
+        if (s->adb_data_in_index >= s->adb_data_in_size) {
+            *data = 0;
+            qemu_irq_raise(s->adb_data_ready);
+            return 1;
+        }
+
+        if (s->adb_data_in_index & 1) {
+            return 0;
+        }
+
+        break;
+
+    case ADB_STATE_IDLE:
+        if (s->adb_data_out_index == 0) {
+            return 0;
+        }
+
+        s->adb_data_in_size = adb_request(&s->adb_bus, s->adb_data_in,
+                                          s->adb_data_out,
+                                          s->adb_data_out_index);
+        s->adb_data_out_index = 0;
+        s->adb_data_in_index = 0;
+        if (s->adb_data_in_size < 0) {
+            *data = 0xff;
+            qemu_irq_raise(s->adb_data_ready);
+            return -1;
+        }
+
+        if (s->adb_data_in_size == 0) {
+            return 0;
+        }
+
+        break;
+    }
+
+    assert(s->adb_data_in_index < sizeof(s->adb_data_in) - 1);
+
+    *data = s->adb_data_in[s->adb_data_in_index++];
+    qemu_irq_raise(s->adb_data_ready);
+    if (*data == 0xff || *data == 0) {
+        return 0;
+    }
+    return 1;
+}
+
+static void via1_adb_update(MacVIAState *m)
+{
+    MOS6522Q800VIA1State *v1s = MOS6522_Q800_VIA1(&m->mos6522_via1);
+    MOS6522State *s = MOS6522(v1s);
+    int state;
+    int ret;
+
+    state = (s->b & VIA1B_vADB_StateMask) >> VIA1B_vADB_StateShift;
+
+    if (s->acr & VIA1ACR_vShiftOut) {
+        /* output mode */
+        ret = adb_via_send(m, state, s->sr);
+        if (ret > 0) {
+            s->b &= ~VIA1B_vADBInt;
+        } else {
+            s->b |= VIA1B_vADBInt;
+        }
+    } else {
+        /* input mode */
+        ret = adb_via_receive(m, state, &s->sr);
+        if (ret > 0 && s->sr != 0xff) {
+            s->b &= ~VIA1B_vADBInt;
+        } else {
+            s->b |= VIA1B_vADBInt;
+        }
+    }
+}
+
+static void via_adb_poll(void *opaque)
+{
+    MacVIAState *m = opaque;
+    MOS6522Q800VIA1State *v1s = MOS6522_Q800_VIA1(&m->mos6522_via1);
+    MOS6522State *s = MOS6522(v1s);
+    int state;
+
+    if (s->b & VIA1B_vADBInt) {
+        state = (s->b & VIA1B_vADB_StateMask) >> VIA1B_vADB_StateShift;
+        if (adb_via_poll(m, state, &s->sr)) {
+            s->b &= ~VIA1B_vADBInt;
+        }
+    }
+
+    timer_mod(m->adb_poll_timer,
+              qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) +
+              (NANOSECONDS_PER_SECOND / VIA_ADB_POLL_FREQ));
+}
+
 static uint64_t mos6522_q800_via1_read(void *opaque, hwaddr addr, unsigned size)
 {
     MOS6522Q800VIA1State *s = MOS6522_Q800_VIA1(opaque);
@@ -553,6 +734,10 @@ static void mac_via_reset(DeviceState *dev)
     MacVIAState *m = MAC_VIA(dev);
     MOS6522Q800VIA1State *v1s = &m->mos6522_via1;
 
+    timer_mod(m->adb_poll_timer,
+              qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) +
+              (NANOSECONDS_PER_SECOND / VIA_ADB_POLL_FREQ));
+
     timer_del(v1s->VBL_timer);
     v1s->next_VBL = 0;
     timer_del(v1s->one_second_timer);
@@ -593,6 +778,10 @@ static void mac_via_realize(DeviceState *dev, Error **errp)
 
     qemu_get_timedate(&tm, 0);
     m->tick_offset = (uint32_t)mktimegm(&tm) + RTC_OFFSET;
+
+    m->adb_poll_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, via_adb_poll, m);
+    m->adb_data_ready = qdev_get_gpio_in_named(dev, "via1-irq",
+                                               VIA1_IRQ_ADB_READY_BIT);
 }
 
 static void mac_via_init(Object *obj)
@@ -642,6 +831,13 @@ static const VMStateDescription vmstate_mac_via = {
         VMSTATE_UINT8(cmd, MacVIAState),
         VMSTATE_INT32(wprotect, MacVIAState),
         VMSTATE_INT32(alt, MacVIAState),
+        /* ADB */
+        VMSTATE_TIMER_PTR(adb_poll_timer, MacVIAState),
+        VMSTATE_INT32(adb_data_in_size, MacVIAState),
+        VMSTATE_INT32(adb_data_in_index, MacVIAState),
+        VMSTATE_INT32(adb_data_out_index, MacVIAState),
+        VMSTATE_BUFFER(adb_data_in, MacVIAState),
+        VMSTATE_BUFFER(adb_data_out, MacVIAState),
         VMSTATE_END_OF_LIST()
     }
 };
@@ -671,6 +867,7 @@ static void mos6522_q800_via1_portB_write(MOS6522State *s)
     MacVIAState *m = container_of(v1s, MacVIAState, mos6522_via1);
 
     via1_rtc_update(m);
+    via1_adb_update(m);
 
     v1s->last_b = s->b;
 }