hw/nios2: Machine with a Vectored Interrupt Controller

Demonstrate how to use nios2 VIC on a machine.
Introduce a new machine property to attach a VIC.

When VIC is present, let the CPU know that it should use the
External Interrupt Interface instead of the Internal Interrupt Interface.
The devices on the machine are attached to the VIC and not directly to cpu.
To allow VIC update EIC fields, we set the "cpu" property of the VIC
with a reference to the nios2 cpu.

[rth: Put a property on the 10m50-ghrd machine, rather than
      create a new machine class.]

Reviewed-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Signed-off-by: Amir Gonnen <amir.gonnen@neuroblade.ai>
Message-Id: <20220303153906.2024748-6-amir.gonnen@neuroblade.ai>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220421151735.31996-63-richard.henderson@linaro.org>

hw/nios2/10m50_devboard.c

@@ -27,6 +27,7 @@
 
 #include "hw/sysbus.h"
 #include "hw/char/serial.h"
+#include "hw/intc/nios2_vic.h"
 #include "hw/qdev-properties.h"
 #include "sysemu/sysemu.h"
 #include "hw/boards.h"
@@ -43,6 +44,8 @@ struct Nios2MachineState {
     MemoryRegion phys_tcm_alias;
     MemoryRegion phys_ram;
     MemoryRegion phys_ram_alias;
+
+    bool vic;
 };
 
 #define TYPE_NIOS2_MACHINE  MACHINE_TYPE_NAME("10m50-ghrd")
@@ -81,10 +84,39 @@ static void nios2_10m50_ghrd_init(MachineState *machine)
     memory_region_add_subregion(address_space_mem, 0xc0000000 + ram_base,
                                 &nms->phys_ram_alias);
 
-    /* Create CPU -- FIXME */
-    cpu = NIOS2_CPU(cpu_create(TYPE_NIOS2_CPU));
-    for (i = 0; i < 32; i++) {
-        irq[i] = qdev_get_gpio_in_named(DEVICE(cpu), "IRQ", i);
+    /* Create CPU.  We need to set eic_present between init and realize. */
+    cpu = NIOS2_CPU(object_new(TYPE_NIOS2_CPU));
+
+    /* Enable the External Interrupt Controller within the CPU. */
+    cpu->eic_present = nms->vic;
+
+    /* Configure new exception vectors. */
+    cpu->reset_addr = 0xd4000000;
+    cpu->exception_addr = 0xc8000120;
+    cpu->fast_tlb_miss_addr = 0xc0000100;
+
+    qdev_realize_and_unref(DEVICE(cpu), NULL, &error_fatal);
+
+    if (nms->vic) {
+        DeviceState *dev = qdev_new(TYPE_NIOS2_VIC);
+        MemoryRegion *dev_mr;
+        qemu_irq cpu_irq;
+
+        object_property_set_link(OBJECT(dev), "cpu", OBJECT(cpu), &error_fatal);
+        sysbus_realize_and_unref(SYS_BUS_DEVICE(dev), &error_fatal);
+
+        cpu_irq = qdev_get_gpio_in_named(DEVICE(cpu), "EIC", 0);
+        sysbus_connect_irq(SYS_BUS_DEVICE(dev), 0, cpu_irq);
+        for (int i = 0; i < 32; i++) {
+            irq[i] = qdev_get_gpio_in(dev, i);
+        }
+
+        dev_mr = sysbus_mmio_get_region(SYS_BUS_DEVICE(dev), 0);
+        memory_region_add_subregion(address_space_mem, 0x18002000, dev_mr);
+    } else {
+        for (i = 0; i < 32; i++) {
+            irq[i] = qdev_get_gpio_in_named(DEVICE(cpu), "IRQ", i);
+        }
     }
 
     /* Register: Altera 16550 UART */
@@ -105,15 +137,22 @@ static void nios2_10m50_ghrd_init(MachineState *machine)
     sysbus_mmio_map(SYS_BUS_DEVICE(dev), 0, 0xe0000880);
     sysbus_connect_irq(SYS_BUS_DEVICE(dev), 0, irq[5]);
 
-    /* Configure new exception vectors and reset CPU for it to take effect. */
-    cpu->reset_addr = 0xd4000000;
-    cpu->exception_addr = 0xc8000120;
-    cpu->fast_tlb_miss_addr = 0xc0000100;
-
     nios2_load_kernel(cpu, ram_base, ram_size, machine->initrd_filename,
                       BINARY_DEVICE_TREE_FILE, NULL);
 }
 
+static bool get_vic(Object *obj, Error **errp)
+{
+    Nios2MachineState *nms = NIOS2_MACHINE(obj);
+    return nms->vic;
+}
+
+static void set_vic(Object *obj, bool value, Error **errp)
+{
+    Nios2MachineState *nms = NIOS2_MACHINE(obj);
+    nms->vic = value;
+}
+
 static void nios2_10m50_ghrd_class_init(ObjectClass *oc, void *data)
 {
     MachineClass *mc = MACHINE_CLASS(oc);
@@ -121,6 +160,10 @@ static void nios2_10m50_ghrd_class_init(ObjectClass *oc, void *data)
     mc->desc = "Altera 10M50 GHRD Nios II design";
     mc->init = nios2_10m50_ghrd_init;
     mc->is_default = true;
+
+    object_class_property_add_bool(oc, "vic", get_vic, set_vic);
+    object_class_property_set_description(oc, "vic",
+        "Set on/off to enable/disable the Vectored Interrupt Controller");
 }
 
 static const TypeInfo nios2_10m50_ghrd_type_info = {

hw/nios2/Kconfig

@@ -3,6 +3,7 @@ config NIOS2_10M50
     select NIOS2
     select SERIAL
     select ALTERA_TIMER
+    select NIOS2_VIC
 
 config NIOS2_GENERIC_NOMMU
     bool