nubus: add support for slot IRQs

Each Nubus slot has an IRQ line that can be used to request service from the
CPU. Connect the IRQs to the Nubus bridge so that they can be wired up using qdev
gpios accordingly, and introduce a new nubus_set_irq() function that can be used
by Nubus devices to control the slot IRQ.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20210924073808.1041-19-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

hw/nubus/nubus-bridge.c

@@ -19,6 +19,8 @@ static void nubus_bridge_init(Object *obj)
     NubusBus *bus = &s->bus;
 
     qbus_create_inplace(bus, sizeof(s->bus), TYPE_NUBUS_BUS, DEVICE(s), NULL);
+
+    qdev_init_gpio_out(DEVICE(s), bus->irqs, NUBUS_IRQS);
 }
 
 static Property nubus_bridge_properties[] = {

hw/nubus/nubus-device.c

@@ -10,12 +10,20 @@
 
 #include "qemu/osdep.h"
 #include "qemu/datadir.h"
+#include "hw/irq.h"
 #include "hw/loader.h"
 #include "hw/nubus/nubus.h"
 #include "qapi/error.h"
 #include "qemu/error-report.h"
 
 
+void nubus_set_irq(NubusDevice *nd, int level)
+{
+    NubusBus *nubus = NUBUS_BUS(qdev_get_parent_bus(DEVICE(nd)));
+
+    qemu_set_irq(nubus->irqs[nd->slot], level);
+}
+
 static void nubus_device_realize(DeviceState *dev, Error **errp)
 {
     NubusBus *nubus = NUBUS_BUS(qdev_get_parent_bus(dev));

include/hw/nubus/nubus.h

@@ -26,6 +26,8 @@
 #define NUBUS_LAST_SLOT       0xf
 #define NUBUS_SLOT_NB         (NUBUS_LAST_SLOT - NUBUS_FIRST_SLOT + 1)
 
+#define NUBUS_IRQS            16
+
 #define TYPE_NUBUS_DEVICE "nubus-device"
 OBJECT_DECLARE_SIMPLE_TYPE(NubusDevice, NUBUS_DEVICE)
 
@@ -45,6 +47,8 @@ struct NubusBus {
     MemoryRegion slot_io;
 
     uint16_t slot_available_mask;
+
+    qemu_irq irqs[NUBUS_IRQS];
 };
 
 #define NUBUS_DECL_ROM_MAX_SIZE    (128 * KiB)
@@ -60,6 +64,8 @@ struct NubusDevice {
     MemoryRegion decl_rom;
 };
 
+void nubus_set_irq(NubusDevice *nd, int level);
+
 struct NubusBridge {
     SysBusDevice parent_obj;