Kernel: Abstract platform-specific serial port access from kprintf

kprintf should not really care about the hardware-specific details of
each UART or serial port out there, so instead of using x86 specific
instructions, let's ensure that we will compile only the relevant code
for debug output for a targeted-specific platform.

Kernel/Arch/DebugOutput.h

@@ -0,0 +1,13 @@
+/*
+ * Copyright (c) 2022, Liav A. <liavalb@hotmail.co.il>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+namespace Kernel {
+
+void debug_output(char ch);
+
+}

Kernel/Arch/aarch64/RPi/DebugOutput.cpp

@@ -0,0 +1,17 @@
+/*
+ * Copyright (c) 2022, Liav A. <liavalb@hotmail.co.il>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <Kernel/Arch/DebugOutput.h>
+#include <Kernel/Arch/aarch64/RPi/UART.h>
+
+namespace Kernel {
+
+void debug_output(char ch)
+{
+    RPi::UART::the().send(ch);
+}
+
+}

Kernel/Arch/x86/common/BochsDebugOutput.h

@@ -0,0 +1,13 @@
+/*
+ * Copyright (c) 2022, Liav A. <liavalb@hotmail.co.il>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+namespace Kernel {
+
+void bochs_debug_output(char ch);
+
+}

Kernel/Arch/x86/common/DebugOutput.cpp

@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2022, Liav A. <liavalb@hotmail.co.il>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <Kernel/Arch/DebugOutput.h>
+#include <Kernel/Arch/x86/IO.h>
+#include <Kernel/Arch/x86/common/BochsDebugOutput.h>
+
+namespace Kernel {
+
+static constexpr u16 serial_com1_io_port = 0x3F8;
+
+void bochs_debug_output(char ch)
+{
+    IO::out8(IO::BOCHS_DEBUG_PORT, ch);
+}
+
+void debug_output(char ch)
+{
+    static bool serial_ready = false;
+    static bool was_cr = false;
+
+    if (!serial_ready) {
+        IO::out8(serial_com1_io_port + 1, 0x00);
+        IO::out8(serial_com1_io_port + 3, 0x80);
+        IO::out8(serial_com1_io_port + 0, 0x02);
+        IO::out8(serial_com1_io_port + 1, 0x00);
+        IO::out8(serial_com1_io_port + 3, 0x03);
+        IO::out8(serial_com1_io_port + 2, 0xC7);
+        IO::out8(serial_com1_io_port + 4, 0x0B);
+
+        serial_ready = true;
+    }
+
+    while ((IO::in8(serial_com1_io_port + 5) & 0x20) == 0)
+        ;
+
+    if (ch == '\n' && !was_cr)
+        IO::out8(serial_com1_io_port, '\r');
+
+    IO::out8(serial_com1_io_port, ch);
+
+    was_cr = ch == '\r';
+}
+
+}

Kernel/CMakeLists.txt

@@ -332,6 +332,7 @@ if ("${SERENITY_ARCH}" STREQUAL "i686" OR "${SERENITY_ARCH}" STREQUAL "x86_64")
         Arch/Processor.cpp
 
         Arch/x86/common/CMOS.cpp
+        Arch/x86/common/DebugOutput.cpp
         Arch/x86/common/Delay.cpp
         Arch/x86/common/I8042Reboot.cpp
         Arch/x86/common/RTC.cpp
@@ -437,6 +438,7 @@ if (NOT "${SERENITY_ARCH}" STREQUAL "aarch64")
     )
 else()
     set(RPI_SOURCES
+        Arch/aarch64/RPi/DebugOutput.cpp
         Arch/aarch64/RPi/Framebuffer.cpp
         Arch/aarch64/RPi/GPIO.cpp
         Arch/aarch64/RPi/InterruptController.cpp

Kernel/kprintf.cpp

@@ -7,7 +7,10 @@
 #include <AK/PrintfImplementation.h>
 #include <AK/StringView.h>
 #include <AK/Types.h>
-#include <Kernel/Arch/x86/IO.h>
+#include <Kernel/Arch/DebugOutput.h>
+#if ARCH(I386) || ARCH(X86_64)
+#    include <Kernel/Arch/x86/common/BochsDebugOutput.h>
+#endif
 #include <Kernel/Devices/ConsoleDevice.h>
 #include <Kernel/Devices/DeviceManagement.h>
 #include <Kernel/Devices/PCISerialDevice.h>
@@ -43,39 +46,20 @@ static void serial_putch(char ch)
     if (PCISerialDevice::is_available())
         return PCISerialDevice::the().put_char(ch);
 
-    static bool serial_ready = false;
-    static bool was_cr = false;
-
-    if (!serial_ready) {
-        IO::out8(0x3F8 + 1, 0x00);
-        IO::out8(0x3F8 + 3, 0x80);
-        IO::out8(0x3F8 + 0, 0x02);
-        IO::out8(0x3F8 + 1, 0x00);
-        IO::out8(0x3F8 + 3, 0x03);
-        IO::out8(0x3F8 + 2, 0xC7);
-        IO::out8(0x3F8 + 4, 0x0B);
-
-        serial_ready = true;
-    }
-
-    while ((IO::in8(0x3F8 + 5) & 0x20) == 0)
-        ;
-
-    if (ch == '\n' && !was_cr)
-        IO::out8(0x3F8, '\r');
-
-    IO::out8(0x3F8, ch);
-
-    was_cr = ch == '\r';
+    debug_output(ch);
 }
 
 static void critical_console_out(char ch)
 {
     if (s_serial_debug_enabled)
         serial_putch(ch);
+
+#if ARCH(I386) || ARCH(X86_64)
     // No need to output things to the real ConsoleDevice as no one is likely
     // to read it (because we are in a fatal situation, so only print things and halt)
-    IO::out8(IO::BOCHS_DEBUG_PORT, ch);
+    bochs_debug_output(ch);
+#endif
+
     // We emit chars directly to the string. this is necessary in few cases,
     // especially when we want to avoid any memory allocations...
     if (GraphicsManagement::is_initialized() && GraphicsManagement::the().console()) {
@@ -95,7 +79,9 @@ static void console_out(char ch)
     if (DeviceManagement::the().is_console_device_attached()) {
         DeviceManagement::the().console_device().put_char(ch);
     } else {
-        IO::out8(IO::BOCHS_DEBUG_PORT, ch);
+#if ARCH(I386) || ARCH(X86_64)
+        bochs_debug_output(ch);
+#endif
     }
     if (ConsoleManagement::is_initialized()) {
         ConsoleManagement::the().debug_tty()->emit_char(ch);
@@ -153,7 +139,9 @@ static inline void internal_dbgputch(char ch)
 {
     if (s_serial_debug_enabled)
         serial_putch(ch);
-    IO::out8(IO::BOCHS_DEBUG_PORT, ch);
+#if ARCH(I386) || ARCH(X86_64)
+    bochs_debug_output(ch);
+#endif
 }
 
 extern "C" void dbgputstr(char const* characters, size_t length)