Kernel: Simplify reboot & poweroff code flow a bit

Instead of using ifdefs to use the correct platform-specific methods, we
can just use the same pattern we use for the microseconds_delay function
which has specific implementations for each Arch CPU subdirectory.

When linking a kernel image, the actual correct and platform-specific
power-state changing methods will be called in Firmware/PowerState.cpp
file.

Kernel/Arch/PowerState.h

@@ -0,0 +1,16 @@
+/*
+ * Copyright (c) 2023, Liav A. <liavalb@hotmail.co.il>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Types.h>
+
+namespace Kernel {
+
+void arch_specific_reboot();
+void arch_specific_poweroff();
+
+}

Kernel/Arch/aarch64/PowerState.cpp

@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2023, Liav A. <liavalb@hotmail.co.il>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <Kernel/Arch/PowerState.h>
+#include <Kernel/Arch/aarch64/RPi/Watchdog.h>
+
+namespace Kernel {
+
+void arch_specific_reboot()
+{
+}
+
+void arch_specific_poweroff()
+{
+    RPi::Watchdog::the().system_shutdown();
+}
+
+}

Kernel/Arch/x86_64/PowerState.cpp

@@ -0,0 +1,24 @@
+/*
+ * Copyright (c) 2023, Liav A. <liavalb@hotmail.co.il>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <Kernel/Arch/PowerState.h>
+#include <Kernel/Arch/x86_64/I8042Reboot.h>
+#include <Kernel/Arch/x86_64/Shutdown.h>
+
+namespace Kernel {
+
+void arch_specific_reboot()
+{
+    i8042_reboot();
+}
+
+void arch_specific_poweroff()
+{
+    qemu_shutdown();
+    virtualbox_shutdown();
+}
+
+}

Kernel/CMakeLists.txt

@@ -209,6 +209,7 @@ set(KERNEL_SOURCES
     Firmware/ACPI/Initialize.cpp
     Firmware/ACPI/Parser.cpp
     Firmware/ACPI/StaticParsing.cpp
+    Firmware/PowerState.cpp
     Interrupts/GenericInterruptHandler.cpp
     Interrupts/IRQHandler.cpp
     Interrupts/PCIIRQHandler.cpp
@@ -402,6 +403,7 @@ if ("${SERENITY_ARCH}" STREQUAL "x86_64")
 
         Arch/x86_64/VGA/IOArbiter.cpp
 
+        Arch/x86_64/PowerState.cpp
         Arch/x86_64/RTC.cpp
         Arch/x86_64/Shutdown.cpp
         Arch/x86_64/SmapDisabler.cpp
@@ -477,6 +479,7 @@ elseif("${SERENITY_ARCH}" STREQUAL "aarch64")
         Arch/aarch64/PageDirectory.cpp
         Arch/aarch64/Panic.cpp
         Arch/aarch64/Processor.cpp
+        Arch/aarch64/PowerState.cpp
         Arch/aarch64/SafeMem.cpp
         Arch/aarch64/SmapDisabler.cpp
         Arch/aarch64/TrapFrame.cpp

Kernel/FileSystem/SysFS/Subsystems/Kernel/PowerStateSwitch.cpp

@@ -6,15 +6,10 @@
  */
 
 #include <AK/Platform.h>
-#if ARCH(X86_64)
-#    include <Kernel/Arch/x86_64/I8042Reboot.h>
-#    include <Kernel/Arch/x86_64/Shutdown.h>
-#elif ARCH(AARCH64)
-#    include <Kernel/Arch/aarch64/RPi/Watchdog.h>
-#endif
 #include <Kernel/FileSystem/FileSystem.h>
 #include <Kernel/FileSystem/SysFS/Subsystems/Kernel/PowerStateSwitch.h>
 #include <Kernel/Firmware/ACPI/Parser.h>
+#include <Kernel/Firmware/PowerState.h>
 #include <Kernel/Sections.h>
 #include <Kernel/TTY/ConsoleManagement.h>
 #include <Kernel/Tasks/Process.h>
@@ -60,55 +55,13 @@ ErrorOr<size_t> SysFSPowerStateSwitchNode::write_bytes(off_t offset, size_t coun
     TRY(data.read(buf, 1));
     switch (buf[0]) {
     case '1':
-        reboot();
+        Firmware::reboot();
         VERIFY_NOT_REACHED();
     case '2':
-        poweroff();
+        Firmware::poweroff();
         VERIFY_NOT_REACHED();
     default:
         return Error::from_errno(EINVAL);
     }
 }
-
-void SysFSPowerStateSwitchNode::reboot()
-{
-    MutexLocker locker(Process::current().big_lock());
-
-    dbgln("acquiring FS locks...");
-    FileSystem::lock_all();
-    dbgln("syncing mounted filesystems...");
-    FileSystem::sync();
-    dbgln("attempting reboot via ACPI");
-    if (ACPI::is_enabled())
-        ACPI::Parser::the()->try_acpi_reboot();
-#if ARCH(X86_64)
-    i8042_reboot();
-#endif
-    dbgln("reboot attempts failed, applications will stop responding.");
-    dmesgln("Reboot can't be completed. It's safe to turn off the computer!");
-    Processor::halt();
-}
-
-void SysFSPowerStateSwitchNode::poweroff()
-{
-    MutexLocker locker(Process::current().big_lock());
-
-    ConsoleManagement::the().switch_to_debug();
-
-    dbgln("acquiring FS locks...");
-    FileSystem::lock_all();
-    dbgln("syncing mounted filesystems...");
-    FileSystem::sync();
-    dbgln("attempting system shutdown...");
-#if ARCH(X86_64)
-    qemu_shutdown();
-    virtualbox_shutdown();
-#elif ARCH(AARCH64)
-    RPi::Watchdog::the().system_shutdown();
-#endif
-    dbgln("shutdown attempts failed, applications will stop responding.");
-    dmesgln("Shutdown can't be completed. It's safe to turn off the computer!");
-    Processor::halt();
-}
-
 }

Kernel/FileSystem/SysFS/Subsystems/Kernel/PowerStateSwitch.h

@@ -29,9 +29,6 @@ public:
 
 private:
     explicit SysFSPowerStateSwitchNode(SysFSDirectory const&);
-
-    void reboot();
-    void poweroff();
 };
 
 }

Kernel/Firmware/PowerState.cpp

@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2023, Liav A. <liavalb@hotmail.co.il>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/Format.h>
+#include <Kernel/Arch/PowerState.h>
+#include <Kernel/FileSystem/FileSystem.h>
+#include <Kernel/Firmware/ACPI/Parser.h>
+#include <Kernel/Firmware/PowerState.h>
+#include <Kernel/TTY/ConsoleManagement.h>
+#include <Kernel/Tasks/Process.h>
+
+namespace Kernel::Firmware {
+
+void reboot()
+{
+    MutexLocker locker(Process::current().big_lock());
+
+    dbgln("acquiring FS locks...");
+    FileSystem::lock_all();
+    dbgln("syncing mounted filesystems...");
+    FileSystem::sync();
+    dbgln("attempting reboot via ACPI");
+    if (ACPI::is_enabled())
+        ACPI::Parser::the()->try_acpi_reboot();
+
+    arch_specific_reboot();
+
+    dbgln("reboot attempts failed, applications will stop responding.");
+    dmesgln("Reboot can't be completed. It's safe to turn off the computer!");
+    Processor::halt();
+}
+
+void poweroff()
+{
+    MutexLocker locker(Process::current().big_lock());
+
+    ConsoleManagement::the().switch_to_debug();
+
+    dbgln("acquiring FS locks...");
+    FileSystem::lock_all();
+    dbgln("syncing mounted filesystems...");
+    FileSystem::sync();
+
+    dbgln("attempting system shutdown...");
+    arch_specific_poweroff();
+
+    dbgln("shutdown attempts failed, applications will stop responding.");
+    dmesgln("Shutdown can't be completed. It's safe to turn off the computer!");
+    Processor::halt();
+}
+
+}

Kernel/Firmware/PowerState.h

@@ -0,0 +1,16 @@
+/*
+ * Copyright (c) 2023, Liav A. <liavalb@hotmail.co.il>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Types.h>
+
+namespace Kernel::Firmware {
+
+void reboot();
+void poweroff();
+
+}