i8259: PREP: Replace pic_intack_read with pic_read_irq

There is nothing in the i8259 spec that justifies the special
pic_intack_read. At least the Linux PREP kernels configure the PICs
properly so that pic_read_irq returns identical values, and setting
read_reg_select in PIC0 cannot be derived from any special i8259 mode.

So switch ppc_prep to pic_read_irq and drop the now unused PIC code.

CC: Andreas Färber <andreas.faerber@web.de>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>

hw/i8259.c

@@ -361,30 +361,6 @@ static void pic_ioport_write(void *opaque, target_phys_addr_t addr64,
     }
 }
 
-static uint32_t pic_poll_read(PicState *s)
-{
-    int ret;
-
-    ret = pic_get_irq(s);
-    if (ret >= 0) {
-        bool slave = (s == &isa_pic->pics[1]);
-
-        if (slave) {
-            s->pics_state->pics[0].isr &= ~(1 << 2);
-            s->pics_state->pics[0].irr &= ~(1 << 2);
-        }
-        s->irr &= ~(1 << ret);
-        s->isr &= ~(1 << ret);
-        if (slave || ret != 2) {
-            pic_update_irq(s);
-        }
-    } else {
-        ret = 0x07;
-    }
-
-    return ret;
-}
-
 static uint64_t pic_ioport_read(void *opaque, target_phys_addr_t addr,
                                 unsigned size)
 {
@@ -414,21 +390,6 @@ static uint64_t pic_ioport_read(void *opaque, target_phys_addr_t addr,
     return ret;
 }
 
-/* memory mapped interrupt status */
-/* XXX: may be the same than pic_read_irq() */
-uint32_t pic_intack_read(PicState2 *s)
-{
-    int ret;
-
-    ret = pic_poll_read(&s->pics[0]);
-    if (ret == 2)
-        ret = pic_poll_read(&s->pics[1]) + 8;
-    /* Prepare for ISR read */
-    s->pics[0].read_reg_select = 1;
-
-    return ret;
-}
-
 int pic_get_output(PicState2 *s)
 {
     return (pic_get_irq(&s->pics[0]) >= 0);

hw/pc.h

@@ -65,7 +65,6 @@ extern PicState2 *isa_pic;
 qemu_irq *i8259_init(qemu_irq parent_irq);
 int pic_read_irq(PicState2 *s);
 int pic_get_output(PicState2 *s);
-uint32_t pic_intack_read(PicState2 *s);
 void pic_info(Monitor *mon);
 void irq_info(Monitor *mon);
 

hw/ppc_prep.c

@@ -130,7 +130,7 @@ static inline uint32_t _PPC_intack_read(target_phys_addr_t addr)
     uint32_t retval = 0;
 
     if ((addr & 0xf) == 0)
-        retval = pic_intack_read(isa_pic);
+        retval = pic_read_irq(isa_pic);
 #if 0
     printf("%s: 0x" TARGET_FMT_plx " <= %08" PRIx32 "\n", __func__, addr,
            retval);