From 5eac2b9f3383413a2050e37a2281bd0ea6096081 Mon Sep 17 00:00:00 2001
From: Timon Kruiper <timonkruiper@gmail.com>
Date: Mon, 30 May 2022 09:30:11 +0200
Subject: [PATCH] Kernel: Add driver for interrupt controller on the Raspberry
 Pi

This implements the simpler IRQController class and adds a
pending_interrupts() function to the class.
---
 Kernel/Arch/aarch64/IRQController.h           |  2 +
 .../Arch/aarch64/RPi/InterruptController.cpp  | 69 +++++++++++++++++++
 Kernel/Arch/aarch64/RPi/InterruptController.h | 39 +++++++++++
 Kernel/CMakeLists.txt                         |  1 +
 4 files changed, 111 insertions(+)
 create mode 100644 Kernel/Arch/aarch64/RPi/InterruptController.cpp
 create mode 100644 Kernel/Arch/aarch64/RPi/InterruptController.h

diff --git a/Kernel/Arch/aarch64/IRQController.h b/Kernel/Arch/aarch64/IRQController.h
index 35882a6ffc..20e6b6b712 100644
--- a/Kernel/Arch/aarch64/IRQController.h
+++ b/Kernel/Arch/aarch64/IRQController.h
@@ -22,6 +22,8 @@ public:
 
     virtual void eoi(GenericInterruptHandler const&) const = 0;
 
+    virtual u64 pending_interrupts() const = 0;
+
     virtual StringView model() const = 0;
 
 protected:
diff --git a/Kernel/Arch/aarch64/RPi/InterruptController.cpp b/Kernel/Arch/aarch64/RPi/InterruptController.cpp
new file mode 100644
index 0000000000..5f44fc11b3
--- /dev/null
+++ b/Kernel/Arch/aarch64/RPi/InterruptController.cpp
@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2022, Timon Kruiper <timonkruiper@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/Format.h>
+#include <Kernel/Arch/aarch64/RPi/InterruptController.h>
+#include <Kernel/Arch/aarch64/RPi/MMIO.h>
+#include <Kernel/Interrupts/GenericInterruptHandler.h>
+
+namespace Kernel::RPi {
+
+// "7.5 Interrupts Registers"
+// https://github.com/raspberrypi/documentation/files/1888662/BCM2837-ARM-Peripherals.-.Revised.-.V2-1.pdf
+struct InterruptControllerRegisters {
+    u32 irq_basic_pending;
+    u32 irq_pending_1;
+    u32 irq_pending_2;
+    u32 fiq_control;
+
+    u32 enable_irqs_1;
+    u32 enable_irqs_2;
+    u32 enable_basic_irqs;
+
+    u32 disable_irqs_1;
+    u32 disable_irqs_2;
+    u32 disable_basic_irqs;
+};
+
+InterruptController::InterruptController()
+    : m_registers(MMIO::the().peripheral<InterruptControllerRegisters>(0xB200))
+{
+}
+
+void InterruptController::enable(GenericInterruptHandler const& handler)
+{
+    u8 interrupt_number = handler.interrupt_number();
+    VERIFY(interrupt_number < 64);
+
+    if (interrupt_number < 32)
+        m_registers->enable_irqs_1 = m_registers->enable_irqs_1 | (1 << interrupt_number);
+    else
+        m_registers->enable_irqs_2 = m_registers->enable_irqs_2 | (1 << (interrupt_number - 32));
+}
+
+void InterruptController::disable(GenericInterruptHandler const& handler)
+{
+    u8 interrupt_number = handler.interrupt_number();
+    VERIFY(interrupt_number < 64);
+
+    if (interrupt_number < 32)
+        m_registers->disable_irqs_1 = m_registers->disable_irqs_1 | (1 << interrupt_number);
+    else
+        m_registers->disable_irqs_2 = m_registers->disable_irqs_2 | (1 << (interrupt_number - 32));
+}
+
+void InterruptController::eoi(GenericInterruptHandler const&) const
+{
+    // NOTE: The interrupt controller cannot clear the interrupt, since it is basically just a big multiplexer.
+    //       The interrupt should be cleared by the corresponding device driver, such as a timer or uart.
+}
+
+u64 InterruptController::pending_interrupts() const
+{
+    return ((u64)m_registers->irq_pending_2 << 32) | (u64)m_registers->irq_pending_1;
+}
+
+}
diff --git a/Kernel/Arch/aarch64/RPi/InterruptController.h b/Kernel/Arch/aarch64/RPi/InterruptController.h
new file mode 100644
index 0000000000..6633a553fe
--- /dev/null
+++ b/Kernel/Arch/aarch64/RPi/InterruptController.h
@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2022, Timon Kruiper <timonkruiper@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Types.h>
+#include <Kernel/Arch/aarch64/IRQController.h>
+
+namespace Kernel::RPi {
+
+struct InterruptControllerRegisters;
+
+// This class implements the simple Interrupt Controller found in the BCM2837. (RPi3)
+// A description of this device can be found at chapter 7 (Interrupts) of the manual:
+// https://github.com/raspberrypi/documentation/files/1888662/BCM2837-ARM-Peripherals.-.Revised.-.V2-1.pdf (RPi3)
+class InterruptController : public IRQController {
+public:
+    InterruptController();
+
+private:
+    virtual void enable(GenericInterruptHandler const&) override;
+    virtual void disable(GenericInterruptHandler const&) override;
+
+    virtual void eoi(GenericInterruptHandler const&) const override;
+
+    virtual u64 pending_interrupts() const override;
+
+    virtual StringView model() const override
+    {
+        return "Raspberry Pi Interrupt Controller";
+    }
+
+    InterruptControllerRegisters volatile* m_registers;
+};
+
+}
diff --git a/Kernel/CMakeLists.txt b/Kernel/CMakeLists.txt
index 5daf2ca395..a5a7c79b50 100644
--- a/Kernel/CMakeLists.txt
+++ b/Kernel/CMakeLists.txt
@@ -401,6 +401,7 @@ else()
     set(RPI_SOURCES
         Arch/aarch64/RPi/Framebuffer.cpp
         Arch/aarch64/RPi/GPIO.cpp
+        Arch/aarch64/RPi/InterruptController.cpp
         Arch/aarch64/RPi/Mailbox.cpp
         Arch/aarch64/RPi/MMIO.cpp
         Arch/aarch64/RPi/Timer.cpp