[PATCH v5 13/31] hw/intc/i8259: Introduce i8259 proxy "isa-pic"

[Bernhard Beschow <shentey@gmail.com>]

Having an i8259 proxy allows for ISA PICs to be created and wired up in
southbridges. This is especially interesting for PIIX3 for two reasons:
First, the southbridge doesn't need to care about the virtualization
technology used (KVM, TCG, Xen) due to in-IRQs (where devices get
attached) and out-IRQs (which will trigger the IRQs of the respective
virtualization technology) are separated. Second, since the in-IRQs are
populated with fully initialized qemu_irq's, they can already be wired
up inside PIIX3.

Cc: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Signed-off-by: Bernhard Beschow <shentey@gmail.com>
---
 include/hw/intc/i8259.h | 19 +++++++++++++++++++
 hw/intc/i8259.c         | 27 +++++++++++++++++++++++++++
 2 files changed, 46 insertions(+)

diff --git a/include/hw/intc/i8259.h b/include/hw/intc/i8259.h
index a0e34dd990..f666f5ee09 100644
--- a/include/hw/intc/i8259.h
+++ b/include/hw/intc/i8259.h
@@ -1,6 +1,25 @@
 #ifndef HW_I8259_H
 #define HW_I8259_H
 
+#include "qom/object.h"
+#include "hw/isa/isa.h"
+#include "qemu/typedefs.h"
+
+#define TYPE_ISA_PIC "isa-pic"
+OBJECT_DECLARE_SIMPLE_TYPE(ISAPICState, ISA_PIC)
+
+/*
+ * TYPE_ISA_PIC is currently a PIC proxy which allows for interrupt wiring in
+ * a virtualization technology agnostic way. It could be turned into a proper
+ * GPIO-based ISA PIC in the future.
+ */
+struct ISAPICState {
+    DeviceState parent_obj;
+
+    qemu_irq in_irqs[ISA_NUM_IRQS];
+    qemu_irq out_irqs[ISA_NUM_IRQS];
+};
+
 /* i8259.c */
 
 extern PICCommonState *isa_pic;
diff --git a/hw/intc/i8259.c b/hw/intc/i8259.c
index 0261f087b2..e99d02136d 100644
--- a/hw/intc/i8259.c
+++ b/hw/intc/i8259.c
@@ -455,9 +455,36 @@ static const TypeInfo i8259_info = {
     .class_size = sizeof(PICClass),
 };
 
+static void isapic_set_irq(void *opaque, int irq, int level)
+{
+    ISAPICState *s = opaque;
+
+    qemu_set_irq(s->out_irqs[irq], level);
+}
+
+static void isapic_init(Object *obj)
+{
+    ISAPICState *s = ISA_PIC(obj);
+
+    qdev_init_gpio_in(DEVICE(s), isapic_set_irq, ISA_NUM_IRQS);
+    qdev_init_gpio_out(DEVICE(s), s->out_irqs, ISA_NUM_IRQS);
+
+    for (int i = 0; i < ISA_NUM_IRQS; ++i) {
+        s->in_irqs[i] = qdev_get_gpio_in(DEVICE(s), i);
+    }
+}
+
+static const TypeInfo isapic_info = {
+    .name          = TYPE_ISA_PIC,
+    .parent        = TYPE_DEVICE,
+    .instance_size = sizeof(ISAPICState),
+    .instance_init = isapic_init,
+};
+
 static void pic_register_types(void)
 {
     type_register_static(&i8259_info);
+    type_register_static(&isapic_info);
 }
 
 type_init(pic_register_types)
-- 
2.39.0