m68k: add a system controller

Add a system controller for the m68k-virt machine.
This controller allows the kernel to power off or reset the machine.

Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20210312214145.2936082-5-laurent@vivier.eu>

docs/specs/virt-ctlr.txt

+Virtual System Controller
+=========================
+
+This device is a simple interface defined for the pure virtual machine with no
+hardware reference implementation to allow the guest kernel to send command
+to the host hypervisor.
+
+The specification can evolve, the current state is defined as below.
+
+This is a MMIO mapped device using 256 bytes.
+
+Two 32bit registers are defined:
+
+1- the features register (read-only, address 0x00)
+
+   This register allows the device to report features supported by the
+   controller.
+   The only feature supported for the moment is power control (0x01).
+
+2- the command register (write-only, address 0x04)
+
+   This register allows the kernel to send the commands to the hypervisor.
+   The implemented commands are part of the power control feature and
+   are reset (1), halt (2) and panic (3).
+   A basic command, no-op (0), is always present and can be used to test the
+   register access. This command has no effect.

hw/misc/Kconfig

@@ -183,4 +183,7 @@ config SIFIVE_U_OTP
 config SIFIVE_U_PRCI
     bool
 
+config VIRT_CTRL
+    bool
+
 source macio/Kconfig

hw/misc/meson.build

@@ -24,6 +24,9 @@ softmmu_ss.add(when: 'CONFIG_ARM11SCU', if_true: files('arm11scu.c'))
 # Mac devices
 softmmu_ss.add(when: 'CONFIG_MOS6522', if_true: files('mos6522.c'))
 
+# virt devices
+softmmu_ss.add(when: 'CONFIG_VIRT_CTRL', if_true: files('virt_ctrl.c'))
+
 # RISC-V devices
 softmmu_ss.add(when: 'CONFIG_MCHP_PFSOC_DMC', if_true: files('mchp_pfsoc_dmc.c'))
 softmmu_ss.add(when: 'CONFIG_MCHP_PFSOC_IOSCB', if_true: files('mchp_pfsoc_ioscb.c'))

hw/misc/trace-events

@@ -255,3 +255,10 @@ pca955x_gpio_change(const char *description, unsigned id, unsigned prev_state, u
 bcm2835_cprman_read(uint64_t offset, uint64_t value) "offset:0x%" PRIx64 " value:0x%" PRIx64
 bcm2835_cprman_write(uint64_t offset, uint64_t value) "offset:0x%" PRIx64 " value:0x%" PRIx64
 bcm2835_cprman_write_invalid_magic(uint64_t offset, uint64_t value) "offset:0x%" PRIx64 " value:0x%" PRIx64
+
+# virt_ctrl.c
+virt_ctrl_read(void *dev, unsigned int addr, unsigned int size, uint64_t value) "ctrl: %p reg: 0x%02x size: %d value: 0x%"PRIx64
+virt_ctrl_write(void *dev, unsigned int addr, unsigned int size, uint64_t value) "ctrl: %p reg: 0x%02x size: %d value: 0x%"PRIx64
+virt_ctrl_reset(void *dev) "ctrl: %p"
+virt_ctrl_realize(void *dev) "ctrl: %p"
+virt_ctrl_instance_init(void *dev) "ctrl: %p"

hw/misc/virt_ctrl.c

+/*
+ * SPDX-License-Identifer: GPL-2.0-or-later
+ *
+ * Virt system Controller
+ */
+
+#include "qemu/osdep.h"
+#include "hw/irq.h"
+#include "hw/qdev-properties.h"
+#include "hw/sysbus.h"
+#include "migration/vmstate.h"
+#include "qemu/log.h"
+#include "trace.h"
+#include "sysemu/runstate.h"
+#include "hw/misc/virt_ctrl.h"
+
+enum {
+    REG_FEATURES = 0x00,
+    REG_CMD      = 0x04,
+};
+
+#define FEAT_POWER_CTRL 0x00000001
+
+enum {
+    CMD_NOOP,
+    CMD_RESET,
+    CMD_HALT,
+    CMD_PANIC,
+};
+
+static uint64_t virt_ctrl_read(void *opaque, hwaddr addr, unsigned size)
+{
+    VirtCtrlState *s = opaque;
+    uint64_t value = 0;
+
+    switch (addr) {
+    case REG_FEATURES:
+        value = FEAT_POWER_CTRL;
+        break;
+    default:
+        qemu_log_mask(LOG_UNIMP,
+                      "%s: unimplemented register read 0x%02"HWADDR_PRIx"\n",
+                      __func__, addr);
+        break;
+    }
+
+    trace_virt_ctrl_write(s, addr, size, value);
+
+    return value;
+}
+
+static void virt_ctrl_write(void *opaque, hwaddr addr, uint64_t value,
+                            unsigned size)
+{
+    VirtCtrlState *s = opaque;
+
+    trace_virt_ctrl_write(s, addr, size, value);
+
+    switch (addr) {
+    case REG_CMD:
+        switch (value) {
+        case CMD_NOOP:
+            break;
+        case CMD_RESET:
+            qemu_system_reset_request(SHUTDOWN_CAUSE_GUEST_RESET);
+            break;
+        case CMD_HALT:
+            qemu_system_shutdown_request(SHUTDOWN_CAUSE_GUEST_SHUTDOWN);
+            break;
+        case CMD_PANIC:
+            qemu_system_shutdown_request(SHUTDOWN_CAUSE_GUEST_PANIC);
+            break;
+        }
+        break;
+    default:
+        qemu_log_mask(LOG_UNIMP,
+                      "%s: unimplemented register write 0x%02"HWADDR_PRIx"\n",
+                      __func__, addr);
+        break;
+    }
+}
+
+static const MemoryRegionOps virt_ctrl_ops = {
+    .read = virt_ctrl_read,
+    .write = virt_ctrl_write,
+    .endianness = DEVICE_NATIVE_ENDIAN,
+    .valid.max_access_size = 4,
+    .impl.max_access_size = 4,
+};
+
+static void virt_ctrl_reset(DeviceState *dev)
+{
+    VirtCtrlState *s = VIRT_CTRL(dev);
+
+    trace_virt_ctrl_reset(s);
+}
+
+static void virt_ctrl_realize(DeviceState *dev, Error **errp)
+{
+    VirtCtrlState *s = VIRT_CTRL(dev);
+
+    trace_virt_ctrl_instance_init(s);
+
+    memory_region_init_io(&s->iomem, OBJECT(s), &virt_ctrl_ops, s,
+                          "virt-ctrl", 0x100);
+}
+
+static const VMStateDescription vmstate_virt_ctrl = {
+    .name = "virt-ctrl",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT32(irq_enabled, VirtCtrlState),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static void virt_ctrl_instance_init(Object *obj)
+{
+    SysBusDevice *dev = SYS_BUS_DEVICE(obj);
+    VirtCtrlState *s = VIRT_CTRL(obj);
+
+    trace_virt_ctrl_instance_init(s);
+
+    sysbus_init_mmio(dev, &s->iomem);
+    sysbus_init_irq(dev, &s->irq);
+}
+
+static void virt_ctrl_class_init(ObjectClass *oc, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(oc);
+
+    dc->reset = virt_ctrl_reset;
+    dc->realize = virt_ctrl_realize;
+    dc->vmsd = &vmstate_virt_ctrl;
+}
+
+static const TypeInfo virt_ctrl_info = {
+    .name = TYPE_VIRT_CTRL,
+    .parent = TYPE_SYS_BUS_DEVICE,
+    .class_init = virt_ctrl_class_init,
+    .instance_init = virt_ctrl_instance_init,
+    .instance_size = sizeof(VirtCtrlState),
+};
+
+static void virt_ctrl_register_types(void)
+{
+    type_register_static(&virt_ctrl_info);
+}
+
+type_init(virt_ctrl_register_types)

include/hw/misc/virt_ctrl.h

+/*
+ * SPDX-License-Identifer: GPL-2.0-or-later
+ *
+ * Virt system Controller
+ */
+
+#ifndef VIRT_CTRL_H
+#define VIRT_CTRL_H
+
+#define TYPE_VIRT_CTRL "virt-ctrl"
+OBJECT_DECLARE_SIMPLE_TYPE(VirtCtrlState, VIRT_CTRL)
+
+struct VirtCtrlState {
+    SysBusDevice parent_obj;
+
+    MemoryRegion iomem;
+    qemu_irq irq;
+
+    uint32_t irq_enabled;
+};
+
+#endif