hw/ppc: Add a test machine for the IBM PPE42 CPU

Adds a test machine for the IBM PPE42 processor, including a
DEC, FIT, WDT and 512 KiB of ram.

The purpose of this machine is only to provide a generic platform
for testing instructions of the recently  added PPE42 processor
model which is used extensively in the IBM Power9, Power10 and
future Power server processors.

Signed-off-by: Glenn Miles <milesg@linux.ibm.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
Link: https://lore.kernel.org/r/20250925201758.652077-9-milesg@linux.ibm.com
Message-ID: <20250925201758.652077-9-milesg@linux.ibm.com>

MAINTAINERS

@@ -1530,6 +1530,12 @@ F: include/hw/pci-host/grackle.h
 F: pc-bios/qemu_vga.ndrv
 F: tests/functional/ppc/test_mac.py
 
+PPE42
+M: Glenn Miles <milesg@linux.ibm.com>
+L: qemu-ppc@nongnu.org
+S: Odd Fixes
+F: hw/ppc/ppe42_machine.c
+
 PReP
 M: Hervé Poussineau <hpoussin@reactos.org>
 L: qemu-ppc@nongnu.org

hw/ppc/Kconfig

@@ -44,6 +44,11 @@ config POWERNV
     select SSI_M25P80
     select PNV_SPI
 
+config PPC405
+    bool
+    default y
+    depends on PPC
+
 config PPC440
     bool
     default y

hw/ppc/meson.build

@@ -57,6 +57,8 @@ ppc_ss.add(when: 'CONFIG_POWERNV', if_true: files(
   'pnv_n1_chiplet.c',
 ))
 # PowerPC 4xx boards
+ppc_ss.add(when: 'CONFIG_PPC405', if_true: files(
+  'ppe42_machine.c'))
 ppc_ss.add(when: 'CONFIG_PPC440', if_true: files(
   'ppc440_bamboo.c',
   'ppc440_uc.c'))

hw/ppc/ppe42_machine.c

@@ -0,0 +1,101 @@
+/*
+ * Test Machine for the IBM PPE42 processor
+ *
+ * Copyright (c) 2025, IBM Corporation.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/units.h"
+#include "qemu/error-report.h"
+#include "system/address-spaces.h"
+#include "hw/boards.h"
+#include "hw/ppc/ppc.h"
+#include "system/system.h"
+#include "system/reset.h"
+#include "system/kvm.h"
+#include "qapi/error.h"
+
+#define TYPE_PPE42_MACHINE MACHINE_TYPE_NAME("ppe42_machine")
+typedef MachineClass Ppe42MachineClass;
+typedef struct Ppe42MachineState Ppe42MachineState;
+DECLARE_OBJ_CHECKERS(Ppe42MachineState, Ppe42MachineClass,
+                     PPE42_MACHINE, TYPE_PPE42_MACHINE)
+
+struct Ppe42MachineState {
+    MachineState parent_obj;
+
+    PowerPCCPU cpu;
+};
+
+static void main_cpu_reset(void *opaque)
+{
+    PowerPCCPU *cpu = opaque;
+
+    cpu_reset(CPU(cpu));
+}
+
+static void ppe42_machine_init(MachineState *machine)
+{
+    Ppe42MachineState *pms = PPE42_MACHINE(machine);
+    PowerPCCPU *cpu = &pms->cpu;
+
+    if (kvm_enabled()) {
+        error_report("machine %s does not support the KVM accelerator",
+                     MACHINE_GET_CLASS(machine)->name);
+        exit(EXIT_FAILURE);
+    }
+    if (machine->ram_size > 512 * KiB) {
+        error_report("RAM size more than 512 KiB is not supported");
+        exit(1);
+    }
+
+    /* init CPU */
+    object_initialize_child(OBJECT(pms), "cpu", cpu, machine->cpu_type);
+    if (!qdev_realize(DEVICE(cpu), NULL, &error_fatal)) {
+        return;
+    }
+
+    qemu_register_reset(main_cpu_reset, cpu);
+
+    /* This sets the decrementer timebase */
+    ppc_booke_timers_init(cpu, 37500000, PPC_TIMER_PPE);
+
+    /* RAM */
+    memory_region_add_subregion(get_system_memory(), 0xfff80000, machine->ram);
+}
+
+
+static void ppe42_machine_class_init(ObjectClass *oc, const void *data)
+{
+    MachineClass *mc = MACHINE_CLASS(oc);
+    static const char * const valid_cpu_types[] = {
+        POWERPC_CPU_TYPE_NAME("PPE42"),
+        POWERPC_CPU_TYPE_NAME("PPE42X"),
+        POWERPC_CPU_TYPE_NAME("PPE42XM"),
+        NULL,
+    };
+
+    mc->desc = "PPE42 Test Machine";
+    mc->init = ppe42_machine_init;
+    mc->default_cpu_type = POWERPC_CPU_TYPE_NAME("PPE42XM");
+    mc->valid_cpu_types = valid_cpu_types;
+    mc->default_ram_id = "ram";
+    mc->default_ram_size = 512 * KiB;
+}
+
+static const TypeInfo ppe42_machine_info = {
+        .name          = TYPE_PPE42_MACHINE,
+        .parent        = TYPE_MACHINE,
+        .instance_size = sizeof(Ppe42MachineState),
+        .class_init    = ppe42_machine_class_init,
+        .class_size    = sizeof(Ppe42MachineClass),
+};
+
+static void ppe42_machine_register_types(void)
+{
+    type_register_static(&ppe42_machine_info);
+}
+
+type_init(ppe42_machine_register_types);