[V4,13/18] i8259: support NEC PC-9821 interface

diff --git a/hw/i8259.c b/hw/i8259.c
index 3de22e3..eaf75dd 100644
--- a/hw/i8259.c
+++ b/hw/i8259.c
@@ -59,6 +59,7 @@  struct PicState2 {
     /* XXX: better separation between the two pics */
     PicState pics[2];
     qemu_irq parent_irq;
+    uint8_t irq_cascade;
     void *irq_request_opaque;
 };
 
@@ -124,7 +125,7 @@  static int pic_get_irq(PicState *s)
     if (s->special_mask)
         mask &= ~s->imr;
     if (s->special_fully_nested_mode && s == &s->pics_state->pics[0])
-        mask &= ~(1 << 2);
+        mask &= ~(1 << s->pics_state->irq_cascade);
     cur_priority = get_priority(s, mask);
     if (priority < cur_priority) {
         /* higher priority found: an irq should be generated */
@@ -145,8 +146,8 @@  void pic_update_irq(PicState2 *s)
     irq2 = pic_get_irq(&s->pics[1]);
     if (irq2 >= 0) {
         /* if irq request by slave pic, signal master PIC */
-        pic_set_irq1(&s->pics[0], 2, 1);
-        pic_set_irq1(&s->pics[0], 2, 0);
+        pic_set_irq1(&s->pics[0], s->irq_cascade, 1);
+        pic_set_irq1(&s->pics[0], s->irq_cascade, 0);
     }
     /* look at requested irq */
     irq = pic_get_irq(&s->pics[0]);
@@ -171,6 +172,11 @@  void pic_update_irq(PicState2 *s)
     else {
         qemu_irq_lower(s->parent_irq);
     }
+#elif defined(TARGET_I386)
+    else if (s->irq_cascade == 7) {
+        /* NEC PC-9821 */
+        qemu_irq_lower(s->parent_irq);
+    }
 #endif
 }
 
@@ -224,7 +230,7 @@  int pic_read_irq(PicState2 *s)
     irq = pic_get_irq(&s->pics[0]);
     if (irq >= 0) {
         pic_intack(&s->pics[0], irq);
-        if (irq == 2) {
+        if (irq == s->irq_cascade) {
             irq2 = pic_get_irq(&s->pics[1]);
             if (irq2 >= 0) {
                 pic_intack(&s->pics[1], irq2);
@@ -377,12 +383,12 @@  static uint32_t pic_poll_read (PicState *s, uint32_t addr1)
     ret = pic_get_irq(s);
     if (ret >= 0) {
         if (addr1 >> 7) {
-            s->pics_state->pics[0].isr &= ~(1 << 2);
-            s->pics_state->pics[0].irr &= ~(1 << 2);
+            s->pics_state->pics[0].isr &= ~(1 << s->pics_state->irq_cascade);
+            s->pics_state->pics[0].irr &= ~(1 << s->pics_state->irq_cascade);
         }
         s->irr &= ~(1 << ret);
         s->isr &= ~(1 << ret);
-        if (addr1 >> 7 || ret != 2)
+        if (addr1 >> 7 || ret != s->pics_state->irq_cascade)
             pic_update_irq(s->pics_state);
     } else {
         ret = 0x07;
@@ -426,7 +432,7 @@  uint32_t pic_intack_read(PicState2 *s)
     int ret;
 
     ret = pic_poll_read(&s->pics[0], 0x00);
-    if (ret == 2)
+    if (ret == s->irq_cascade)
         ret = pic_poll_read(&s->pics[1], 0x80) + 8;
     /* Prepare for ISR read */
     s->pics[0].read_reg_select = 1;
@@ -530,6 +536,47 @@  qemu_irq *i8259_init(qemu_irq parent_irq)
     s->pics[0].elcr_mask = 0xf8;
     s->pics[1].elcr_mask = 0xde;
     s->parent_irq = parent_irq;
+    s->irq_cascade = 2;
+    s->pics[0].pics_state = s;
+    s->pics[1].pics_state = s;
+    isa_pic = s;
+    return qemu_allocate_irqs(i8259_set_irq, s, 16);
+}
+
+/* NEC PC-9821 */
+
+static void pc98_pic_ioport_write(void *opaque, uint32_t addr, uint32_t val)
+{
+    pic_ioport_write(opaque, addr >> 1, val);
+}
+
+static uint32_t pc98_pic_ioport_read(void *opaque, uint32_t addr)
+{
+    return pic_ioport_read(opaque, addr >> 1);
+}
+
+static void pc98_pic_init1(int io_addr, PicState *s)
+{
+    int i;
+    for (i = 0; i < 2; i++) {
+        register_ioport_write(io_addr + (i << 1), 1, 1, pc98_pic_ioport_write, s);
+        register_ioport_read(io_addr + (i << 1), 1, 1, pc98_pic_ioport_read, s);
+    }
+    vmstate_register(io_addr, &vmstate_pic, s);
+    qemu_register_reset(pic_reset, s);
+}
+
+qemu_irq *pc98_i8259_init(qemu_irq parent_irq)
+{
+    PicState2 *s;
+
+    s = qemu_mallocz(sizeof(PicState2));
+    pc98_pic_init1(0x00, &s->pics[0]);
+    pc98_pic_init1(0x08, &s->pics[1]);
+    s->pics[0].elcr_mask = 0;
+    s->pics[1].elcr_mask = 0;
+    s->parent_irq = parent_irq;
+    s->irq_cascade = 7;
     s->pics[0].pics_state = s;
     s->pics[1].pics_state = s;
     isa_pic = s;